civetweb.c

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/* Copyright (c) 2013-2018 the Civetweb developers
 * Copyright (c) 2004-2013 Sergey Lyubka
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#if defined(__GNUC__) || defined(__MINGW32__)
#define GCC_VERSION                                                            \
   (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
#if GCC_VERSION >= 40500
/* gcc diagnostic pragmas available */
#define GCC_DIAGNOSTIC
#endif
#endif

#if defined(GCC_DIAGNOSTIC)
/* Disable unused macros warnings - not all defines are required
 * for all systems and all compilers. */
#pragma GCC diagnostic ignored "-Wunused-macros"
/* A padding warning is just plain useless */
#pragma GCC diagnostic ignored "-Wpadded"
#endif

#if defined(__clang__) /* GCC does not (yet) support this pragma */
/* We must set some flags for the headers we include. These flags
 * are reserved ids according to C99, so we need to disable a
 * warning for that. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wreserved-id-macro"
#endif

#if defined(_WIN32)
#if !defined(_CRT_SECURE_NO_WARNINGS)
#define _CRT_SECURE_NO_WARNINGS /* Disable deprecation warning in VS2005 */
#endif
#if !defined(_WIN32_WINNT) /* defined for tdm-gcc so we can use getnameinfo */
#define _WIN32_WINNT 0x0501
#endif
#else
#if !defined(_GNU_SOURCE)
#define _GNU_SOURCE /* for setgroups(), pthread_setname_np() */
#endif
#if defined(__linux__) && !defined(_XOPEN_SOURCE)
#define _XOPEN_SOURCE 600 /* For flockfile() on Linux */
#endif
#if !defined(_LARGEFILE_SOURCE)
#define _LARGEFILE_SOURCE /* For fseeko(), ftello() */
#endif
#if !defined(_FILE_OFFSET_BITS)
#define _FILE_OFFSET_BITS 64 /* Use 64-bit file offsets by default */
#endif
#if !defined(__STDC_FORMAT_MACROS)
#define __STDC_FORMAT_MACROS /* <inttypes.h> wants this for C++ */
#endif
#if !defined(__STDC_LIMIT_MACROS)
#define __STDC_LIMIT_MACROS /* C++ wants that for INT64_MAX */
#endif
#if !defined(_DARWIN_UNLIMITED_SELECT)
#define _DARWIN_UNLIMITED_SELECT
#endif
#if defined(__sun)
#define __EXTENSIONS__  /* to expose flockfile and friends in stdio.h */
#define __inline inline /* not recognized on older compiler versions */
#endif
#endif

#if defined(__clang__)
/* Enable reserved-id-macro warning again. */
#pragma GCC diagnostic pop
#endif


#if defined(USE_LUA)
#define USE_TIMERS
#endif

#if defined(_MSC_VER)
/* 'type cast' : conversion from 'int' to 'HANDLE' of greater size */
#pragma warning(disable : 4306)
/* conditional expression is constant: introduced by FD_SET(..) */
#pragma warning(disable : 4127)
/* non-constant aggregate initializer: issued due to missing C99 support */
#pragma warning(disable : 4204)
/* padding added after data member */
#pragma warning(disable : 4820)
/* not defined as a preprocessor macro, replacing with '0' for '#if/#elif' */
#pragma warning(disable : 4668)
/* no function prototype given: converting '()' to '(void)' */
#pragma warning(disable : 4255)
/* function has been selected for automatic inline expansion */
#pragma warning(disable : 4711)
#endif


/* This code uses static_assert to check some conditions.
 * Unfortunately some compilers still do not support it, so we have a
 * replacement function here. */
#if defined(__STDC_VERSION__) && __STDC_VERSION__ > 201100L
#define mg_static_assert _Static_assert
#elif defined(__cplusplus) && __cplusplus >= 201103L
#define mg_static_assert static_assert
#else
char static_assert_replacement[1];
#define mg_static_assert(cond, txt)                                            \
   extern char static_assert_replacement[(cond) ? 1 : -1]
#endif

mg_static_assert(sizeof(int) == 4 || sizeof(int) == 8,
                 "int data type size check");
mg_static_assert(sizeof(void *) == 4 || sizeof(void *) == 8,
                 "pointer data type size check");
mg_static_assert(sizeof(void *) >= sizeof(int), "data type size check");


/* Alternative queue is well tested and should be the new default */
#if defined(NO_ALTERNATIVE_QUEUE)
#if defined(ALTERNATIVE_QUEUE)
#error "Define ALTERNATIVE_QUEUE or NO_ALTERNATIVE_QUEUE or none, but not both"
#endif
#else
#define ALTERNATIVE_QUEUE
#endif


/* DTL -- including winsock2.h works better if lean and mean */
#if !defined(WIN32_LEAN_AND_MEAN)
#define WIN32_LEAN_AND_MEAN
#endif

#if defined(__SYMBIAN32__)
/* According to https://en.wikipedia.org/wiki/Symbian#History,
 * Symbian is no longer maintained since 2014-01-01.
 * Recent versions of CivetWeb are no longer tested for Symbian.
 * It makes no sense, to support an abandoned operating system.
 */
#error "Symbian is no longer maintained. CivetWeb no longer supports Symbian."
#define NO_SSL /* SSL is not supported */
#define NO_CGI /* CGI is not supported */
#define PATH_MAX FILENAME_MAX
#endif /* __SYMBIAN32__ */


#if !defined(CIVETWEB_HEADER_INCLUDED)
/* Include the header file here, so the CivetWeb interface is defined for the
 * entire implementation, including the following forward definitions. */
#include "civetweb.h"
#endif

#if !defined(DEBUG_TRACE)
#if defined(DEBUG)
static void DEBUG_TRACE_FUNC(const char *func,
                             unsigned line,
                             PRINTF_FORMAT_STRING(const char *fmt),
                             ...) PRINTF_ARGS(3, 4);

#define DEBUG_TRACE(fmt, ...)                                                  \
   DEBUG_TRACE_FUNC(__func__, __LINE__, fmt, __VA_ARGS__)

#define NEED_DEBUG_TRACE_FUNC

#else
#define DEBUG_TRACE(fmt, ...)                                                  \
   do {                                                                       \
   } while (0)
#endif /* DEBUG */
#endif /* DEBUG_TRACE */


#if !defined(DEBUG_ASSERT)
#if defined(DEBUG)
#define DEBUG_ASSERT(cond)                                                     \
   do {                                                                       \
      if (!(cond)) {                                                         \
         DEBUG_TRACE("ASSERTION FAILED: %s", #cond);                        \
         exit(2); /* Exit with error */                                     \
      }                                                                      \
   } while (0)
#else
#define DEBUG_ASSERT(cond)
#endif /* DEBUG */
#endif


#if defined(__GNUC__) && defined(GCC_INSTRUMENTATION)
void __cyg_profile_func_enter(void *this_fn, void *call_site)
    __attribute__((no_instrument_function));

void __cyg_profile_func_exit(void *this_fn, void *call_site)
    __attribute__((no_instrument_function));

void
__cyg_profile_func_enter(void *this_fn, void *call_site)
{
   if ((void *)this_fn != (void *)printf) {
      printf("E %p %p\n", this_fn, call_site);
   }
}

void
__cyg_profile_func_exit(void *this_fn, void *call_site)
{
   if ((void *)this_fn != (void *)printf) {
      printf("X %p %p\n", this_fn, call_site);
   }
}
#endif


#if !defined(IGNORE_UNUSED_RESULT)
#define IGNORE_UNUSED_RESULT(a) ((void)((a) && 1))
#endif


#if defined(__GNUC__) || defined(__MINGW32__)

/* GCC unused function attribute seems fundamentally broken.
 * Several attempts to tell the compiler "THIS FUNCTION MAY BE USED
 * OR UNUSED" for individual functions failed.
 * Either the compiler creates an "unused-function" warning if a
 * function is not marked with __attribute__((unused)).
 * On the other hand, if the function is marked with this attribute,
 * but is used, the compiler raises a completely idiotic
 * "used-but-marked-unused" warning - and
 *   #pragma GCC diagnostic ignored "-Wused-but-marked-unused"
 * raises error: unknown option after "#pragma GCC diagnostic".
 * Disable this warning completely, until the GCC guys sober up
 * again.
 */

#pragma GCC diagnostic ignored "-Wunused-function"

#define FUNCTION_MAY_BE_UNUSED /* __attribute__((unused)) */

#else
#define FUNCTION_MAY_BE_UNUSED
#endif


/* Some ANSI #includes are not available on Windows CE */
#if !defined(_WIN32_WCE)
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/types.h>
#endif /* !_WIN32_WCE */


#if defined(__clang__)
/* When using -Weverything, clang does not accept it's own headers
 * in a release build configuration. Disable what is too much in
 * -Weverything. */
#pragma clang diagnostic ignored "-Wdisabled-macro-expansion"
#endif

#if defined(__GNUC__) || defined(__MINGW32__)
/* Who on earth came to the conclusion, using __DATE__ should rise
 * an "expansion of date or time macro is not reproducible"
 * warning. That's exactly what was intended by using this macro.
 * Just disable this nonsense warning. */

/* And disabling them does not work either:
 * #pragma clang diagnostic ignored "-Wno-error=date-time"
 * #pragma clang diagnostic ignored "-Wdate-time"
 * So we just have to disable ALL warnings for some lines
 * of code.
 * This seems to be a known GCC bug, not resolved since 2012:
 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53431
 */
#endif


#if defined(__MACH__) /* Apple OSX section */

#if defined(__clang__)
#if (__clang_major__ == 3) && ((__clang_minor__ == 7) || (__clang_minor__ == 8))
/* Avoid warnings for Xcode 7. It seems it does no longer exist in Xcode 8 */
#pragma clang diagnostic ignored "-Wno-reserved-id-macro"
#pragma clang diagnostic ignored "-Wno-keyword-macro"
#endif
#endif

#define CLOCK_MONOTONIC (1)
#define CLOCK_REALTIME (2)

#include <mach/clock.h>
#include <mach/mach.h>
#include <mach/mach_time.h>
#include <sys/errno.h>
#include <sys/time.h>

/* clock_gettime is not implemented on OSX prior to 10.12 */
static int
_civet_clock_gettime(int clk_id, struct timespec *t)
{
   memset(t, 0, sizeof(*t));
   if (clk_id == CLOCK_REALTIME) {
      struct timeval now;
      int rv = gettimeofday(&now, NULL);
      if (rv) {
         return rv;
      }
      t->tv_sec = now.tv_sec;
      t->tv_nsec = now.tv_usec * 1000;
      return 0;

   } else if (clk_id == CLOCK_MONOTONIC) {
      static uint64_t clock_start_time = 0;
      static mach_timebase_info_data_t timebase_ifo = {0, 0};

      uint64_t now = mach_absolute_time();

      if (clock_start_time == 0) {
         kern_return_t mach_status = mach_timebase_info(&timebase_ifo);
         DEBUG_ASSERT(mach_status == KERN_SUCCESS);

         /* appease "unused variable" warning for release builds */
         (void)mach_status;

         clock_start_time = now;
      }

      now = (uint64_t)((double)(now - clock_start_time)
                       * (double)timebase_ifo.numer
                       / (double)timebase_ifo.denom);

      t->tv_sec = now / 1000000000;
      t->tv_nsec = now % 1000000000;
      return 0;
   }
   return -1; /* EINVAL - Clock ID is unknown */
}

/* if clock_gettime is declared, then __CLOCK_AVAILABILITY will be defined */
#if defined(__CLOCK_AVAILABILITY)
/* If we compiled with Mac OSX 10.12 or later, then clock_gettime will be
 * declared but it may be NULL at runtime. So we need to check before using
 * it. */
static int
_civet_safe_clock_gettime(int clk_id, struct timespec *t)
{
   if (clock_gettime) {
      return clock_gettime(clk_id, t);
   }
   return _civet_clock_gettime(clk_id, t);
}
#define clock_gettime _civet_safe_clock_gettime
#else
#define clock_gettime _civet_clock_gettime
#endif

#endif


#include <ctype.h>
#include <limits.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

/********************************************************************/
/* CivetWeb configuration defines */
/********************************************************************/

/* Maximum number of threads that can be configured.
 * The number of threads actually created depends on the "num_threads"
 * configuration parameter, but this is the upper limit. */
#if !defined(MAX_WORKER_THREADS)
#define MAX_WORKER_THREADS (1024 * 64) /* in threads (count) */
#endif

/* Timeout interval for select/poll calls.
 * The timeouts depend on "*_timeout_ms" configuration values, but long
 * timeouts are split into timouts as small as SOCKET_TIMEOUT_QUANTUM.
 * This reduces the time required to stop the server. */
#if !defined(SOCKET_TIMEOUT_QUANTUM)
#define SOCKET_TIMEOUT_QUANTUM (2000) /* in ms */
#endif

/* Do not try to compress files smaller than this limit. */
#if !defined(MG_FILE_COMPRESSION_SIZE_LIMIT)
#define MG_FILE_COMPRESSION_SIZE_LIMIT (1024) /* in bytes */
#endif

#if !defined(PASSWORDS_FILE_NAME)
#define PASSWORDS_FILE_NAME ".htpasswd"
#endif

/* Initial buffer size for all CGI environment variables. In case there is
 * not enough space, another block is allocated. */
#if !defined(CGI_ENVIRONMENT_SIZE)
#define CGI_ENVIRONMENT_SIZE (4096) /* in bytes */
#endif

/* Maximum number of environment variables. */
#if !defined(MAX_CGI_ENVIR_VARS)
#define MAX_CGI_ENVIR_VARS (256) /* in variables (count) */
#endif

/* General purpose buffer size. */
#if !defined(MG_BUF_LEN) /* in bytes */
#define MG_BUF_LEN (1024 * 8)
#endif

/* Size of the accepted socket queue (in case the old queue implementation
 * is used). */
#if !defined(MGSQLEN)
#define MGSQLEN (20) /* count */
#endif


/********************************************************************/

/* Helper makros */
#define ARRAY_SIZE(array) (sizeof(array) / sizeof(array[0]))

/* Standard defines */
#if !defined(INT64_MAX)
#define INT64_MAX (9223372036854775807)
#endif

#define SHUTDOWN_RD (0)
#define SHUTDOWN_WR (1)
#define SHUTDOWN_BOTH (2)

mg_static_assert(MAX_WORKER_THREADS >= 1,
                 "worker threads must be a positive number");

mg_static_assert(sizeof(size_t) == 4 || sizeof(size_t) == 8,
                 "size_t data type size check");

#if defined(_WIN32) /* WINDOWS include block */
#include <windows.h>
#include <winsock2.h> /* DTL add for SO_EXCLUSIVE */
#include <ws2tcpip.h>

typedef const char *SOCK_OPT_TYPE;

#if !defined(PATH_MAX)
#define W_PATH_MAX (MAX_PATH)
/* at most three UTF-8 chars per wchar_t */
#define PATH_MAX (W_PATH_MAX * 3)
#else
#define W_PATH_MAX ((PATH_MAX + 2) / 3)
#endif

mg_static_assert(PATH_MAX >= 1, "path length must be a positive number");

#if !defined(_IN_PORT_T)
#if !defined(in_port_t)
#define in_port_t u_short
#endif
#endif

#if !defined(_WIN32_WCE)
#include <direct.h>
#include <io.h>
#include <process.h>
#else            /* _WIN32_WCE */
#define NO_CGI   /* WinCE has no pipes */
#define NO_POPEN /* WinCE has no popen */

typedef long off_t;

#define errno ((int)(GetLastError()))
#define strerror(x) (_ultoa(x, (char *)_alloca(sizeof(x) * 3), 10))
#endif /* _WIN32_WCE */

#define MAKEUQUAD(lo, hi)                                                      \
   ((uint64_t)(((uint32_t)(lo)) | ((uint64_t)((uint32_t)(hi))) << 32))
#define RATE_DIFF (10000000) /* 100 nsecs */
#define EPOCH_DIFF (MAKEUQUAD(0xd53e8000, 0x019db1de))
#define SYS2UNIX_TIME(lo, hi)                                                  \
   ((time_t)((MAKEUQUAD((lo), (hi)) - EPOCH_DIFF) / RATE_DIFF))

/* Visual Studio 6 does not know __func__ or __FUNCTION__
 * The rest of MS compilers use __FUNCTION__, not C99 __func__
 * Also use _strtoui64 on modern M$ compilers */
#if defined(_MSC_VER)
#if (_MSC_VER < 1300)
#define STRX(x) #x
#define STR(x) STRX(x)
#define __func__ __FILE__ ":" STR(__LINE__)
#define strtoull(x, y, z) ((unsigned __int64)_atoi64(x))
#define strtoll(x, y, z) (_atoi64(x))
#else
#define __func__ __FUNCTION__
#define strtoull(x, y, z) (_strtoui64(x, y, z))
#define strtoll(x, y, z) (_strtoi64(x, y, z))
#endif
#endif /* _MSC_VER */

#define ERRNO ((int)(GetLastError()))
#define NO_SOCKLEN_T

#if defined(_WIN64) || defined(__MINGW64__)
#if !defined(SSL_LIB)
#define SSL_LIB "ssleay64.dll"
#endif
#if !defined(CRYPTO_LIB)
#define CRYPTO_LIB "libeay64.dll"
#endif
#else
#if !defined(SSL_LIB)
#define SSL_LIB "ssleay32.dll"
#endif
#if !defined(CRYPTO_LIB)
#define CRYPTO_LIB "libeay32.dll"
#endif
#endif

#define O_NONBLOCK (0)
#if !defined(W_OK)
#define W_OK (2) /* http://msdn.microsoft.com/en-us/library/1w06ktdy.aspx */
#endif
#if !defined(EWOULDBLOCK)
#define EWOULDBLOCK WSAEWOULDBLOCK
#endif /* !EWOULDBLOCK */
#define _POSIX_
#define INT64_FMT "I64d"
#define UINT64_FMT "I64u"

#define WINCDECL __cdecl
#define vsnprintf_impl _vsnprintf
#define access _access
#define mg_sleep(x) (Sleep(x))

#define pipe(x) _pipe(x, MG_BUF_LEN, _O_BINARY)
#if !defined(popen)
#define popen(x, y) (_popen(x, y))
#endif
#if !defined(pclose)
#define pclose(x) (_pclose(x))
#endif
#define close(x) (_close(x))
#define dlsym(x, y) (GetProcAddress((HINSTANCE)(x), (y)))
#define RTLD_LAZY (0)
#define fseeko(x, y, z) ((_lseeki64(_fileno(x), (y), (z)) == -1) ? -1 : 0)
#define fdopen(x, y) (_fdopen((x), (y)))
#define write(x, y, z) (_write((x), (y), (unsigned)z))
#define read(x, y, z) (_read((x), (y), (unsigned)z))
#define flockfile(x) (EnterCriticalSection(&global_log_file_lock))
#define funlockfile(x) (LeaveCriticalSection(&global_log_file_lock))
#define sleep(x) (Sleep((x)*1000))
#define rmdir(x) (_rmdir(x))
#if defined(_WIN64) || !defined(__MINGW32__)
/* Only MinGW 32 bit is missing this function */
#define timegm(x) (_mkgmtime(x))
#else
time_t timegm(struct tm *tm);
#define NEED_TIMEGM
#endif


#if !defined(fileno)
#define fileno(x) (_fileno(x))
#endif /* !fileno MINGW #defines fileno */

typedef HANDLE pthread_mutex_t;
typedef DWORD pthread_key_t;
typedef HANDLE pthread_t;
typedef struct {
   CRITICAL_SECTION threadIdSec;
   struct mg_workerTLS *waiting_thread; /* The chain of threads */
} pthread_cond_t;

#if !defined(__clockid_t_defined)
typedef DWORD clockid_t;
#endif
#if !defined(CLOCK_MONOTONIC)
#define CLOCK_MONOTONIC (1)
#endif
#if !defined(CLOCK_REALTIME)
#define CLOCK_REALTIME (2)
#endif
#if !defined(CLOCK_THREAD)
#define CLOCK_THREAD (3)
#endif
#if !defined(CLOCK_PROCESS)
#define CLOCK_PROCESS (4)
#endif


#if defined(_MSC_VER) && (_MSC_VER >= 1900)
#define _TIMESPEC_DEFINED
#endif
#if !defined(_TIMESPEC_DEFINED)
struct timespec {
   time_t tv_sec; /* seconds */
   long tv_nsec;  /* nanoseconds */
};
#endif

#if !defined(WIN_PTHREADS_TIME_H)
#define MUST_IMPLEMENT_CLOCK_GETTIME
#endif

#if defined(MUST_IMPLEMENT_CLOCK_GETTIME)
#define clock_gettime mg_clock_gettime
static int
clock_gettime(clockid_t clk_id, struct timespec *tp)
{
   FILETIME ft;
   ULARGE_INTEGER li, li2;
   BOOL ok = FALSE;
   double d;
   static double perfcnt_per_sec = 0.0;
   static BOOL initialized = FALSE;

   if (!initialized) {
      QueryPerformanceFrequency((LARGE_INTEGER *)&li);
      perfcnt_per_sec = 1.0 / li.QuadPart;
      initialized = TRUE;
   }

   if (tp) {
      memset(tp, 0, sizeof(*tp));

      if (clk_id == CLOCK_REALTIME) {

         /* BEGIN: CLOCK_REALTIME = wall clock (date and time) */
         GetSystemTimeAsFileTime(&ft);
         li.LowPart = ft.dwLowDateTime;
         li.HighPart = ft.dwHighDateTime;
         li.QuadPart -= 116444736000000000; /* 1.1.1970 in filedate */
         tp->tv_sec = (time_t)(li.QuadPart / 10000000);
         tp->tv_nsec = (long)(li.QuadPart % 10000000) * 100;
         ok = TRUE;
         /* END: CLOCK_REALTIME */

      } else if (clk_id == CLOCK_MONOTONIC) {

         /* BEGIN: CLOCK_MONOTONIC = stopwatch (time differences) */
         QueryPerformanceCounter((LARGE_INTEGER *)&li);
         d = li.QuadPart * perfcnt_per_sec;
         tp->tv_sec = (time_t)d;
         d -= (double)tp->tv_sec;
         tp->tv_nsec = (long)(d * 1.0E9);
         ok = TRUE;
         /* END: CLOCK_MONOTONIC */

      } else if (clk_id == CLOCK_THREAD) {

         /* BEGIN: CLOCK_THREAD = CPU usage of thread */
         FILETIME t_create, t_exit, t_kernel, t_user;
         if (GetThreadTimes(GetCurrentThread(),
                            &t_create,
                            &t_exit,
                            &t_kernel,
                            &t_user)) {
            li.LowPart = t_user.dwLowDateTime;
            li.HighPart = t_user.dwHighDateTime;
            li2.LowPart = t_kernel.dwLowDateTime;
            li2.HighPart = t_kernel.dwHighDateTime;
            li.QuadPart += li2.QuadPart;
            tp->tv_sec = (time_t)(li.QuadPart / 10000000);
            tp->tv_nsec = (long)(li.QuadPart % 10000000) * 100;
            ok = TRUE;
         }
         /* END: CLOCK_THREAD */

      } else if (clk_id == CLOCK_PROCESS) {

         /* BEGIN: CLOCK_PROCESS = CPU usage of process */
         FILETIME t_create, t_exit, t_kernel, t_user;
         if (GetProcessTimes(GetCurrentProcess(),
                             &t_create,
                             &t_exit,
                             &t_kernel,
                             &t_user)) {
            li.LowPart = t_user.dwLowDateTime;
            li.HighPart = t_user.dwHighDateTime;
            li2.LowPart = t_kernel.dwLowDateTime;
            li2.HighPart = t_kernel.dwHighDateTime;
            li.QuadPart += li2.QuadPart;
            tp->tv_sec = (time_t)(li.QuadPart / 10000000);
            tp->tv_nsec = (long)(li.QuadPart % 10000000) * 100;
            ok = TRUE;
         }
         /* END: CLOCK_PROCESS */

      } else {

         /* BEGIN: unknown clock */
         /* ok = FALSE; already set by init */
         /* END: unknown clock */
      }
   }

   return ok ? 0 : -1;
}
#endif


#define pid_t HANDLE /* MINGW typedefs pid_t to int. Using #define here. */

static int pthread_mutex_lock(pthread_mutex_t *);
static int pthread_mutex_unlock(pthread_mutex_t *);
static void path_to_unicode(const struct mg_connection *conn,
                            const char *path,
                            wchar_t *wbuf,
                            size_t wbuf_len);

/* All file operations need to be rewritten to solve #246. */

struct mg_file;

static const char *
mg_fgets(char *buf, size_t size, struct mg_file *filep, char **p);


/* POSIX dirent interface */
struct dirent {
   char d_name[PATH_MAX];
};

typedef struct DIR {
   HANDLE handle;
   WIN32_FIND_DATAW info;
   struct dirent result;
} DIR;

#if defined(_WIN32)
#if !defined(HAVE_POLL)
struct pollfd {
   SOCKET fd;
   short events;
   short revents;
};
#endif
#endif

/* Mark required libraries */
#if defined(_MSC_VER)
#pragma comment(lib, "Ws2_32.lib")
#endif

#else /* defined(_WIN32) - WINDOWS vs UNIX include block */

#include <arpa/inet.h>
#include <inttypes.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <stdint.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/utsname.h>
#include <sys/wait.h>
typedef const void *SOCK_OPT_TYPE;

#if defined(ANDROID)
typedef unsigned short int in_port_t;
#endif

#include <dirent.h>
#include <grp.h>
#include <pwd.h>
#include <unistd.h>
#define vsnprintf_impl vsnprintf

#if !defined(NO_SSL_DL) && !defined(NO_SSL)
#include <dlfcn.h>
#endif
#include <pthread.h>
#if defined(__MACH__)
#define SSL_LIB "libssl.dylib"
#define CRYPTO_LIB "libcrypto.dylib"
#else
#if !defined(SSL_LIB)
#define SSL_LIB "libssl.so"
#endif
#if !defined(CRYPTO_LIB)
#define CRYPTO_LIB "libcrypto.so"
#endif
#endif
#if !defined(O_BINARY)
#define O_BINARY (0)
#endif /* O_BINARY */
#define closesocket(a) (close(a))
#define mg_mkdir(conn, path, mode) (mkdir(path, mode))
#define mg_remove(conn, x) (remove(x))
#define mg_sleep(x) (usleep((x)*1000))
#define mg_opendir(conn, x) (opendir(x))
#define mg_closedir(x) (closedir(x))
#define mg_readdir(x) (readdir(x))
#define ERRNO (errno)
#define INVALID_SOCKET (-1)
#define INT64_FMT PRId64
#define UINT64_FMT PRIu64
typedef int SOCKET;
#define WINCDECL

#if defined(__hpux)
/* HPUX 11 does not have monotonic, fall back to realtime */
#if !defined(CLOCK_MONOTONIC)
#define CLOCK_MONOTONIC CLOCK_REALTIME
#endif

/* HPUX defines socklen_t incorrectly as size_t which is 64bit on
 * Itanium.  Without defining _XOPEN_SOURCE or _XOPEN_SOURCE_EXTENDED
 * the prototypes use int* rather than socklen_t* which matches the
 * actual library expectation.  When called with the wrong size arg
 * accept() returns a zero client inet addr and check_acl() always
 * fails.  Since socklen_t is widely used below, just force replace
 * their typedef with int. - DTL
 */
#define socklen_t int
#endif /* hpux */

#endif /* defined(_WIN32) - WINDOWS vs UNIX include block */

/* Maximum queue length for pending connections. This value is passed as
 * parameter to the "listen" socket call. */
#if !defined(SOMAXCONN)
/* This symbol may be defined in winsock2.h so this must after that include */
#define SOMAXCONN (100) /* in pending connections (count) */
#endif

/* In case our C library is missing "timegm", provide an implementation */
#if defined(NEED_TIMEGM)
static inline int
is_leap(int y)
{
   return (y % 4 == 0 && y % 100 != 0) || y % 400 == 0;
}

static inline int
count_leap(int y)
{
   return (y - 1969) / 4 - (y - 1901) / 100 + (y - 1601) / 400;
}

time_t
timegm(struct tm *tm)
{
   static const unsigned short ydays[] = {
       0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365};
   int year = tm->tm_year + 1900;
   int mon = tm->tm_mon;
   int mday = tm->tm_mday - 1;
   int hour = tm->tm_hour;
   int min = tm->tm_min;
   int sec = tm->tm_sec;

   if (year < 1970 || mon < 0 || mon > 11 || mday < 0
       || (mday >= ydays[mon + 1] - ydays[mon]
                       + (mon == 1 && is_leap(year) ? 1 : 0))
       || hour < 0 || hour > 23 || min < 0 || min > 59 || sec < 0 || sec > 60)
      return -1;

   time_t res = year - 1970;
   res *= 365;
   res += mday;
   res += ydays[mon] + (mon > 1 && is_leap(year) ? 1 : 0);
   res += count_leap(year);

   res *= 24;
   res += hour;
   res *= 60;
   res += min;
   res *= 60;
   res += sec;
   return res;
}
#endif /* NEED_TIMEGM */


/* va_copy should always be a macro, C99 and C++11 - DTL */
#if !defined(va_copy)
#define va_copy(x, y) ((x) = (y))
#endif


#if defined(_WIN32)
/* Create substitutes for POSIX functions in Win32. */

#if defined(GCC_DIAGNOSTIC)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif


static CRITICAL_SECTION global_log_file_lock;

FUNCTION_MAY_BE_UNUSED
static DWORD
pthread_self(void)
{
   return GetCurrentThreadId();
}


FUNCTION_MAY_BE_UNUSED
static int
pthread_key_create(
    pthread_key_t *key,
    void (*_ignored)(void *) /* destructor not supported for Windows */
)
{
   (void)_ignored;

   if ((key != 0)) {
      *key = TlsAlloc();
      return (*key != TLS_OUT_OF_INDEXES) ? 0 : -1;
   }
   return -2;
}


FUNCTION_MAY_BE_UNUSED
static int
pthread_key_delete(pthread_key_t key)
{
   return TlsFree(key) ? 0 : 1;
}


FUNCTION_MAY_BE_UNUSED
static int
pthread_setspecific(pthread_key_t key, void *value)
{
   return TlsSetValue(key, value) ? 0 : 1;
}


FUNCTION_MAY_BE_UNUSED
static void *
pthread_getspecific(pthread_key_t key)
{
   return TlsGetValue(key);
}

#if defined(GCC_DIAGNOSTIC)
/* Enable unused function warning again */
#pragma GCC diagnostic pop
#endif

static struct pthread_mutex_undefined_struct *pthread_mutex_attr = NULL;
#else
static pthread_mutexattr_t pthread_mutex_attr;
#endif /* _WIN32 */


#if defined(_WIN32_WCE)
/* Create substitutes for POSIX functions in Win32. */

#if defined(GCC_DIAGNOSTIC)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif


FUNCTION_MAY_BE_UNUSED
static time_t
time(time_t *ptime)
{
   time_t t;
   SYSTEMTIME st;
   FILETIME ft;

   GetSystemTime(&st);
   SystemTimeToFileTime(&st, &ft);
   t = SYS2UNIX_TIME(ft.dwLowDateTime, ft.dwHighDateTime);

   if (ptime != NULL) {
      *ptime = t;
   }

   return t;
}


FUNCTION_MAY_BE_UNUSED
static struct tm *
localtime_s(const time_t *ptime, struct tm *ptm)
{
   int64_t t = ((int64_t)*ptime) * RATE_DIFF + EPOCH_DIFF;
   FILETIME ft, lft;
   SYSTEMTIME st;
   TIME_ZONE_INFORMATION tzinfo;

   if (ptm == NULL) {
      return NULL;
   }

   *(int64_t *)&ft = t;
   FileTimeToLocalFileTime(&ft, &lft);
   FileTimeToSystemTime(&lft, &st);
   ptm->tm_year = st.wYear - 1900;
   ptm->tm_mon = st.wMonth - 1;
   ptm->tm_wday = st.wDayOfWeek;
   ptm->tm_mday = st.wDay;
   ptm->tm_hour = st.wHour;
   ptm->tm_min = st.wMinute;
   ptm->tm_sec = st.wSecond;
   ptm->tm_yday = 0; /* hope nobody uses this */
   ptm->tm_isdst =
       (GetTimeZoneInformation(&tzinfo) == TIME_ZONE_ID_DAYLIGHT) ? 1 : 0;

   return ptm;
}


FUNCTION_MAY_BE_UNUSED
static struct tm *
gmtime_s(const time_t *ptime, struct tm *ptm)
{
   /* FIXME(lsm): fix this. */
   return localtime_s(ptime, ptm);
}


static int mg_atomic_inc(volatile int *addr);
static struct tm tm_array[MAX_WORKER_THREADS];
static int tm_index = 0;


FUNCTION_MAY_BE_UNUSED
static struct tm *
localtime(const time_t *ptime)
{
   int i = mg_atomic_inc(&tm_index) % (sizeof(tm_array) / sizeof(tm_array[0]));
   return localtime_s(ptime, tm_array + i);
}


FUNCTION_MAY_BE_UNUSED
static struct tm *
gmtime(const time_t *ptime)
{
   int i = mg_atomic_inc(&tm_index) % ARRAY_SIZE(tm_array);
   return gmtime_s(ptime, tm_array + i);
}


FUNCTION_MAY_BE_UNUSED
static size_t
strftime(char *dst, size_t dst_size, const char *fmt, const struct tm *tm)
{
   /* TODO: (void)mg_snprintf(NULL, dst, dst_size, "implement strftime()
    * for WinCE"); */
   return 0;
}

#define _beginthreadex(psec, stack, func, prm, flags, ptid)                    \
   (uintptr_t) CreateThread(psec, stack, func, prm, flags, ptid)

#define remove(f) mg_remove(NULL, f)


FUNCTION_MAY_BE_UNUSED
static int
rename(const char *a, const char *b)
{
   wchar_t wa[W_PATH_MAX];
   wchar_t wb[W_PATH_MAX];
   path_to_unicode(NULL, a, wa, ARRAY_SIZE(wa));
   path_to_unicode(NULL, b, wb, ARRAY_SIZE(wb));

   return MoveFileW(wa, wb) ? 0 : -1;
}


struct stat {
   int64_t st_size;
   time_t st_mtime;
};


FUNCTION_MAY_BE_UNUSED
static int
stat(const char *name, struct stat *st)
{
   wchar_t wbuf[W_PATH_MAX];
   WIN32_FILE_ATTRIBUTE_DATA attr;
   time_t creation_time, write_time;

   path_to_unicode(NULL, name, wbuf, ARRAY_SIZE(wbuf));
   memset(&attr, 0, sizeof(attr));

   GetFileAttributesExW(wbuf, GetFileExInfoStandard, &attr);
   st->st_size =
       (((int64_t)attr.nFileSizeHigh) << 32) + (int64_t)attr.nFileSizeLow;

   write_time = SYS2UNIX_TIME(attr.ftLastWriteTime.dwLowDateTime,
                              attr.ftLastWriteTime.dwHighDateTime);
   creation_time = SYS2UNIX_TIME(attr.ftCreationTime.dwLowDateTime,
                                 attr.ftCreationTime.dwHighDateTime);

   if (creation_time > write_time) {
      st->st_mtime = creation_time;
   } else {
      st->st_mtime = write_time;
   }
   return 0;
}

#define access(x, a) 1 /* not required anyway */

/* WinCE-TODO: define stat, remove, rename, _rmdir, _lseeki64 */
/* Values from errno.h in Windows SDK (Visual Studio). */
#define EEXIST 17
#define EACCES 13
#define ENOENT 2

#if defined(GCC_DIAGNOSTIC)
/* Enable unused function warning again */
#pragma GCC diagnostic pop
#endif

#endif /* defined(_WIN32_WCE) */


#if defined(GCC_DIAGNOSTIC)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif /* defined(GCC_DIAGNOSTIC) */
#if defined(__clang__)
/* Show no warning in case system functions are not used. */
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-function"
#endif

static pthread_mutex_t global_lock_mutex;


#if defined(_WIN32)
/* Forward declaration for Windows */
FUNCTION_MAY_BE_UNUSED
static int pthread_mutex_lock(pthread_mutex_t *mutex);

FUNCTION_MAY_BE_UNUSED
static int pthread_mutex_unlock(pthread_mutex_t *mutex);
#endif


FUNCTION_MAY_BE_UNUSED
static void
mg_global_lock(void)
{
   (void)pthread_mutex_lock(&global_lock_mutex);
}


FUNCTION_MAY_BE_UNUSED
static void
mg_global_unlock(void)
{
   (void)pthread_mutex_unlock(&global_lock_mutex);
}


FUNCTION_MAY_BE_UNUSED
static int
mg_atomic_inc(volatile int *addr)
{
   int ret;
#if defined(_WIN32) && !defined(NO_ATOMICS)
   /* Depending on the SDK, this function uses either
    * (volatile unsigned int *) or (volatile LONG *),
    * so whatever you use, the other SDK is likely to raise a warning. */
   ret = InterlockedIncrement((volatile long *)addr);
#elif defined(__GNUC__)                                                        \
    && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 0)))           \
    && !defined(NO_ATOMICS)
   ret = __sync_add_and_fetch(addr, 1);
#else
   mg_global_lock();
   ret = (++(*addr));
   mg_global_unlock();
#endif
   return ret;
}


FUNCTION_MAY_BE_UNUSED
static int
mg_atomic_dec(volatile int *addr)
{
   int ret;
#if defined(_WIN32) && !defined(NO_ATOMICS)
   /* Depending on the SDK, this function uses either
    * (volatile unsigned int *) or (volatile LONG *),
    * so whatever you use, the other SDK is likely to raise a warning. */
   ret = InterlockedDecrement((volatile long *)addr);
#elif defined(__GNUC__)                                                        \
    && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 0)))           \
    && !defined(NO_ATOMICS)
   ret = __sync_sub_and_fetch(addr, 1);
#else
   mg_global_lock();
   ret = (--(*addr));
   mg_global_unlock();
#endif
   return ret;
}


#if defined(USE_SERVER_STATS)
static int64_t
mg_atomic_add(volatile int64_t *addr, int64_t value)
{
   int64_t ret;
#if defined(_WIN64) && !defined(NO_ATOMICS)
   ret = InterlockedAdd64(addr, value);
#elif defined(__GNUC__)                                                        \
    && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 0)))           \
    && !defined(NO_ATOMICS)
   ret = __sync_add_and_fetch(addr, value);
#else
   mg_global_lock();
   *addr += value;
   ret = (*addr);
   mg_global_unlock();
#endif
   return ret;
}
#endif


#if defined(GCC_DIAGNOSTIC)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic pop
#endif /* defined(GCC_DIAGNOSTIC) */
#if defined(__clang__)
/* Show no warning in case system functions are not used. */
#pragma clang diagnostic pop
#endif


#if defined(USE_SERVER_STATS)

struct mg_memory_stat {
   volatile int64_t totalMemUsed;
   volatile int64_t maxMemUsed;
   volatile int blockCount;
};


static struct mg_memory_stat *get_memory_stat(struct mg_context *ctx);


static void *
mg_malloc_ex(size_t size,
             struct mg_context *ctx,
             const char *file,
             unsigned line)
{
   void *data = malloc(size + 2 * sizeof(uintptr_t));
   void *memory = 0;
   struct mg_memory_stat *mstat = get_memory_stat(ctx);

#if defined(MEMORY_DEBUGGING)
   char mallocStr[256];
#else
   (void)file;
   (void)line;
#endif

   if (data) {
      int64_t mmem = mg_atomic_add(&mstat->totalMemUsed, (int64_t)size);
      if (mmem > mstat->maxMemUsed) {
         /* could use atomic compare exchange, but this
          * seems overkill for statistics data */
         mstat->maxMemUsed = mmem;
      }

      mg_atomic_inc(&mstat->blockCount);
      ((uintptr_t *)data)[0] = size;
      ((uintptr_t *)data)[1] = (uintptr_t)mstat;
      memory = (void *)(((char *)data) + 2 * sizeof(uintptr_t));
   }

#if defined(MEMORY_DEBUGGING)
   sprintf(mallocStr,
           "MEM: %p %5lu alloc   %7lu %4lu --- %s:%u\n",
           memory,
           (unsigned long)size,
           (unsigned long)mstat->totalMemUsed,
           (unsigned long)mstat->blockCount,
           file,
           line);
#if defined(_WIN32)
   OutputDebugStringA(mallocStr);
#else
   DEBUG_TRACE("%s", mallocStr);
#endif
#endif

   return memory;
}


static void *
mg_calloc_ex(size_t count,
             size_t size,
             struct mg_context *ctx,
             const char *file,
             unsigned line)
{
   void *data = mg_malloc_ex(size * count, ctx, file, line);

   if (data) {
      memset(data, 0, size * count);
   }
   return data;
}


static void
mg_free_ex(void *memory, const char *file, unsigned line)
{
   void *data = (void *)(((char *)memory) - 2 * sizeof(uintptr_t));


#if defined(MEMORY_DEBUGGING)
   char mallocStr[256];
#else
   (void)file;
   (void)line;
#endif

   if (memory) {
      uintptr_t size = ((uintptr_t *)data)[0];
      struct mg_memory_stat *mstat =
          (struct mg_memory_stat *)(((uintptr_t *)data)[1]);
      mg_atomic_add(&mstat->totalMemUsed, -(int64_t)size);
      mg_atomic_dec(&mstat->blockCount);
#if defined(MEMORY_DEBUGGING)
      sprintf(mallocStr,
              "MEM: %p %5lu free    %7lu %4lu --- %s:%u\n",
              memory,
              (unsigned long)size,
              (unsigned long)mstat->totalMemUsed,
              (unsigned long)mstat->blockCount,
              file,
              line);
#if defined(_WIN32)
      OutputDebugStringA(mallocStr);
#else
      DEBUG_TRACE("%s", mallocStr);
#endif
#endif
      free(data);
   }
}


static void *
mg_realloc_ex(void *memory,
              size_t newsize,
              struct mg_context *ctx,
              const char *file,
              unsigned line)
{
   void *data;
   void *_realloc;
   uintptr_t oldsize;

#if defined(MEMORY_DEBUGGING)
   char mallocStr[256];
#else
   (void)file;
   (void)line;
#endif

   if (newsize) {
      if (memory) {
         /* Reallocate existing block */
         struct mg_memory_stat *mstat;
         data = (void *)(((char *)memory) - 2 * sizeof(uintptr_t));
         oldsize = ((uintptr_t *)data)[0];
         mstat = (struct mg_memory_stat *)((uintptr_t *)data)[1];
         _realloc = realloc(data, newsize + 2 * sizeof(uintptr_t));
         if (_realloc) {
            data = _realloc;
            mg_atomic_add(&mstat->totalMemUsed, -(int64_t)oldsize);
#if defined(MEMORY_DEBUGGING)
            sprintf(mallocStr,
                    "MEM: %p %5lu r-free  %7lu %4lu --- %s:%u\n",
                    memory,
                    (unsigned long)oldsize,
                    (unsigned long)mstat->totalMemUsed,
                    (unsigned long)mstat->blockCount,
                    file,
                    line);
#if defined(_WIN32)
            OutputDebugStringA(mallocStr);
#else
            DEBUG_TRACE("%s", mallocStr);
#endif
#endif
            mg_atomic_add(&mstat->totalMemUsed, (int64_t)newsize);
#if defined(MEMORY_DEBUGGING)
            sprintf(mallocStr,
                    "MEM: %p %5lu r-alloc %7lu %4lu --- %s:%u\n",
                    memory,
                    (unsigned long)newsize,
                    (unsigned long)mstat->totalMemUsed,
                    (unsigned long)mstat->blockCount,
                    file,
                    line);
#if defined(_WIN32)
            OutputDebugStringA(mallocStr);
#else
            DEBUG_TRACE("%s", mallocStr);
#endif
#endif
            *(uintptr_t *)data = newsize;
            data = (void *)(((char *)data) + 2 * sizeof(uintptr_t));
         } else {
#if defined(MEMORY_DEBUGGING)
#if defined(_WIN32)
            OutputDebugStringA("MEM: realloc failed\n");
#else
            DEBUG_TRACE("%s", "MEM: realloc failed\n");
#endif
#endif
            return _realloc;
         }
      } else {
         /* Allocate new block */
         data = mg_malloc_ex(newsize, ctx, file, line);
      }
   } else {
      /* Free existing block */
      data = 0;
      mg_free_ex(memory, file, line);
   }

   return data;
}

#define mg_malloc(a) mg_malloc_ex(a, NULL, __FILE__, __LINE__)
#define mg_calloc(a, b) mg_calloc_ex(a, b, NULL, __FILE__, __LINE__)
#define mg_realloc(a, b) mg_realloc_ex(a, b, NULL, __FILE__, __LINE__)
#define mg_free(a) mg_free_ex(a, __FILE__, __LINE__)

#define mg_malloc_ctx(a, c) mg_malloc_ex(a, c, __FILE__, __LINE__)
#define mg_calloc_ctx(a, b, c) mg_calloc_ex(a, b, c, __FILE__, __LINE__)
#define mg_realloc_ctx(a, b, c) mg_realloc_ex(a, b, c, __FILE__, __LINE__)

#else /* USE_SERVER_STATS */

static __inline void *
mg_malloc(size_t a)
{
   return malloc(a);
}

static __inline void *
mg_calloc(size_t a, size_t b)
{
   return calloc(a, b);
}

static __inline void *
mg_realloc(void *a, size_t b)
{
   return realloc(a, b);
}

static __inline void
mg_free(void *a)
{
   free(a);
}

#define mg_malloc_ctx(a, c) mg_malloc(a)
#define mg_calloc_ctx(a, b, c) mg_calloc(a, b)
#define mg_realloc_ctx(a, b, c) mg_realloc(a, b)
#define mg_free_ctx(a, c) mg_free(a)

#endif /* USE_SERVER_STATS */


static void mg_vsnprintf(const struct mg_connection *conn,
                         int *truncated,
                         char *buf,
                         size_t buflen,
                         const char *fmt,
                         va_list ap);

static void mg_snprintf(const struct mg_connection *conn,
                        int *truncated,
                        char *buf,
                        size_t buflen,
                        PRINTF_FORMAT_STRING(const char *fmt),
                        ...) PRINTF_ARGS(5, 6);

/* This following lines are just meant as a reminder to use the mg-functions
 * for memory management */
#if defined(malloc)
#undef malloc
#endif
#if defined(calloc)
#undef calloc
#endif
#if defined(realloc)
#undef realloc
#endif
#if defined(free)
#undef free
#endif
#if defined(snprintf)
#undef snprintf
#endif
#if defined(vsnprintf)
#undef vsnprintf
#endif
#define malloc DO_NOT_USE_THIS_FUNCTION__USE_mg_malloc
#define calloc DO_NOT_USE_THIS_FUNCTION__USE_mg_calloc
#define realloc DO_NOT_USE_THIS_FUNCTION__USE_mg_realloc
#define free DO_NOT_USE_THIS_FUNCTION__USE_mg_free
#define snprintf DO_NOT_USE_THIS_FUNCTION__USE_mg_snprintf
#if defined(_WIN32)
/* vsnprintf must not be used in any system,
 * but this define only works well for Windows. */
#define vsnprintf DO_NOT_USE_THIS_FUNCTION__USE_mg_vsnprintf
#endif


/* mg_init_library counter */
static int mg_init_library_called = 0;

#if !defined(NO_SSL)
static int mg_ssl_initialized = 0;
#endif

static pthread_key_t sTlsKey; /* Thread local storage index */
static int thread_idx_max = 0;

#if defined(MG_LEGACY_INTERFACE)
#define MG_ALLOW_USING_GET_REQUEST_INFO_FOR_RESPONSE
#endif

struct mg_workerTLS {
   int is_master;
   unsigned long thread_idx;
#if defined(_WIN32)
   HANDLE pthread_cond_helper_mutex;
   struct mg_workerTLS *next_waiting_thread;
#endif
#if defined(MG_ALLOW_USING_GET_REQUEST_INFO_FOR_RESPONSE)
   char txtbuf[4];
#endif
};


#if defined(GCC_DIAGNOSTIC)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif /* defined(GCC_DIAGNOSTIC) */
#if defined(__clang__)
/* Show no warning in case system functions are not used. */
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-function"
#endif


/* Get a unique thread ID as unsigned long, independent from the data type
 * of thread IDs defined by the operating system API.
 * If two calls to mg_current_thread_id  return the same value, they calls
 * are done from the same thread. If they return different values, they are
 * done from different threads. (Provided this function is used in the same
 * process context and threads are not repeatedly created and deleted, but
 * CivetWeb does not do that).
 * This function must match the signature required for SSL id callbacks:
 * CRYPTO_set_id_callback
 */
FUNCTION_MAY_BE_UNUSED
static unsigned long
mg_current_thread_id(void)
{
#if defined(_WIN32)
   return GetCurrentThreadId();
#else

#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunreachable-code"
/* For every compiler, either "sizeof(pthread_t) > sizeof(unsigned long)"
 * or not, so one of the two conditions will be unreachable by construction.
 * Unfortunately the C standard does not define a way to check this at
 * compile time, since the #if preprocessor conditions can not use the sizeof
 * operator as an argument. */
#endif

   if (sizeof(pthread_t) > sizeof(unsigned long)) {
      /* This is the problematic case for CRYPTO_set_id_callback:
       * The OS pthread_t can not be cast to unsigned long. */
      struct mg_workerTLS *tls =
          (struct mg_workerTLS *)pthread_getspecific(sTlsKey);
      if (tls == NULL) {
         /* SSL called from an unknown thread: Create some thread index.
          */
         tls = (struct mg_workerTLS *)mg_malloc(sizeof(struct mg_workerTLS));
         tls->is_master = -2; /* -2 means "3rd party thread" */
         tls->thread_idx = (unsigned)mg_atomic_inc(&thread_idx_max);
         pthread_setspecific(sTlsKey, tls);
      }
      return tls->thread_idx;
   } else {
      /* pthread_t may be any data type, so a simple cast to unsigned long
       * can rise a warning/error, depending on the platform.
       * Here memcpy is used as an anything-to-anything cast. */
      unsigned long ret = 0;
      pthread_t t = pthread_self();
      memcpy(&ret, &t, sizeof(pthread_t));
      return ret;
   }

#if defined(__clang__)
#pragma clang diagnostic pop
#endif

#endif
}


FUNCTION_MAY_BE_UNUSED
static uint64_t
mg_get_current_time_ns(void)
{
   struct timespec tsnow;
   clock_gettime(CLOCK_REALTIME, &tsnow);
   return (((uint64_t)tsnow.tv_sec) * 1000000000) + (uint64_t)tsnow.tv_nsec;
}


#if defined(GCC_DIAGNOSTIC)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic pop
#endif /* defined(GCC_DIAGNOSTIC) */
#if defined(__clang__)
/* Show no warning in case system functions are not used. */
#pragma clang diagnostic pop
#endif


#if defined(NEED_DEBUG_TRACE_FUNC)
static void
DEBUG_TRACE_FUNC(const char *func, unsigned line, const char *fmt, ...)
{
   va_list args;
   uint64_t nsnow;
   static uint64_t nslast;
   struct timespec tsnow;

   /* Get some operating system independent thread id */
   unsigned long thread_id = mg_current_thread_id();

   clock_gettime(CLOCK_REALTIME, &tsnow);
   nsnow = ((uint64_t)tsnow.tv_sec) * ((uint64_t)1000000000)
           + ((uint64_t)tsnow.tv_nsec);

   if (!nslast) {
      nslast = nsnow;
   }

   flockfile(stdout);
   printf("*** %lu.%09lu %12" INT64_FMT " %lu %s:%u: ",
          (unsigned long)tsnow.tv_sec,
          (unsigned long)tsnow.tv_nsec,
          nsnow - nslast,
          thread_id,
          func,
          line);
   va_start(args, fmt);
   vprintf(fmt, args);
   va_end(args);
   putchar('\n');
   fflush(stdout);
   funlockfile(stdout);
   nslast = nsnow;
}
#endif /* NEED_DEBUG_TRACE_FUNC */


#define MD5_STATIC static
#include "md5.inl"

/* Darwin prior to 7.0 and Win32 do not have socklen_t */
#if defined(NO_SOCKLEN_T)
typedef int socklen_t;
#endif /* NO_SOCKLEN_T */

#define IP_ADDR_STR_LEN (50) /* IPv6 hex string is 46 chars */

#if !defined(MSG_NOSIGNAL)
#define MSG_NOSIGNAL (0)
#endif


#if defined(NO_SSL)
typedef struct SSL SSL; /* dummy for SSL argument to push/pull */
typedef struct SSL_CTX SSL_CTX;
#else
#if defined(NO_SSL_DL)
#include <openssl/bn.h>
#include <openssl/conf.h>
#include <openssl/crypto.h>
#include <openssl/dh.h>
#include <openssl/engine.h>
#include <openssl/err.h>
#include <openssl/opensslv.h>
#include <openssl/pem.h>
#include <openssl/ssl.h>
#include <openssl/tls1.h>
#include <openssl/x509.h>

#if defined(WOLFSSL_VERSION)
/* Additional defines for WolfSSL, see
 * https://github.com/civetweb/civetweb/issues/583 */
#include "wolfssl_extras.inl"
#endif

#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
/* If OpenSSL headers are included, automatically select the API version */
#if !defined(OPENSSL_API_1_1)
#define OPENSSL_API_1_1
#endif
#define OPENSSL_REMOVE_THREAD_STATE()
#else
#define OPENSSL_REMOVE_THREAD_STATE() ERR_remove_thread_state(NULL)
#endif

#else

/* SSL loaded dynamically from DLL.
 * I put the prototypes here to be independent from OpenSSL source
 * installation. */

typedef struct ssl_st SSL;
typedef struct ssl_method_st SSL_METHOD;
typedef struct ssl_ctx_st SSL_CTX;
typedef struct x509_store_ctx_st X509_STORE_CTX;
typedef struct x509_name X509_NAME;
typedef struct asn1_integer ASN1_INTEGER;
typedef struct bignum BIGNUM;
typedef struct ossl_init_settings_st OPENSSL_INIT_SETTINGS;
typedef struct evp_md EVP_MD;
typedef struct x509 X509;


#define SSL_CTRL_OPTIONS (32)
#define SSL_CTRL_CLEAR_OPTIONS (77)
#define SSL_CTRL_SET_ECDH_AUTO (94)

#define OPENSSL_INIT_NO_LOAD_SSL_STRINGS 0x00100000L
#define OPENSSL_INIT_LOAD_SSL_STRINGS 0x00200000L
#define OPENSSL_INIT_LOAD_CRYPTO_STRINGS 0x00000002L

#define SSL_VERIFY_NONE (0)
#define SSL_VERIFY_PEER (1)
#define SSL_VERIFY_FAIL_IF_NO_PEER_CERT (2)
#define SSL_VERIFY_CLIENT_ONCE (4)
#define SSL_OP_ALL ((long)(0x80000BFFUL))
#define SSL_OP_NO_SSLv2 (0x01000000L)
#define SSL_OP_NO_SSLv3 (0x02000000L)
#define SSL_OP_NO_TLSv1 (0x04000000L)
#define SSL_OP_NO_TLSv1_2 (0x08000000L)
#define SSL_OP_NO_TLSv1_1 (0x10000000L)
#define SSL_OP_SINGLE_DH_USE (0x00100000L)
#define SSL_OP_CIPHER_SERVER_PREFERENCE (0x00400000L)
#define SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION (0x00010000L)
#define SSL_OP_NO_COMPRESSION (0x00020000L)

#define SSL_CB_HANDSHAKE_START (0x10)
#define SSL_CB_HANDSHAKE_DONE (0x20)

#define SSL_ERROR_NONE (0)
#define SSL_ERROR_SSL (1)
#define SSL_ERROR_WANT_READ (2)
#define SSL_ERROR_WANT_WRITE (3)
#define SSL_ERROR_WANT_X509_LOOKUP (4)
#define SSL_ERROR_SYSCALL (5) /* see errno */
#define SSL_ERROR_ZERO_RETURN (6)
#define SSL_ERROR_WANT_CONNECT (7)
#define SSL_ERROR_WANT_ACCEPT (8)

#define TLSEXT_TYPE_server_name (0)
#define TLSEXT_NAMETYPE_host_name (0)
#define SSL_TLSEXT_ERR_OK (0)
#define SSL_TLSEXT_ERR_ALERT_WARNING (1)
#define SSL_TLSEXT_ERR_ALERT_FATAL (2)
#define SSL_TLSEXT_ERR_NOACK (3)

struct ssl_func {
   const char *name;  /* SSL function name */
   void (*ptr)(void); /* Function pointer */
};


#if defined(OPENSSL_API_1_1)

#define SSL_free (*(void (*)(SSL *))ssl_sw[0].ptr)
#define SSL_accept (*(int (*)(SSL *))ssl_sw[1].ptr)
#define SSL_connect (*(int (*)(SSL *))ssl_sw[2].ptr)
#define SSL_read (*(int (*)(SSL *, void *, int))ssl_sw[3].ptr)
#define SSL_write (*(int (*)(SSL *, const void *, int))ssl_sw[4].ptr)
#define SSL_get_error (*(int (*)(SSL *, int))ssl_sw[5].ptr)
#define SSL_set_fd (*(int (*)(SSL *, SOCKET))ssl_sw[6].ptr)
#define SSL_new (*(SSL * (*)(SSL_CTX *)) ssl_sw[7].ptr)
#define SSL_CTX_new (*(SSL_CTX * (*)(SSL_METHOD *)) ssl_sw[8].ptr)
#define TLS_server_method (*(SSL_METHOD * (*)(void)) ssl_sw[9].ptr)
#define OPENSSL_init_ssl                                                       \
   (*(int (*)(uint64_t opts,                                                  \
              const OPENSSL_INIT_SETTINGS *settings))ssl_sw[10]               \
         .ptr)
#define SSL_CTX_use_PrivateKey_file                                            \
   (*(int (*)(SSL_CTX *, const char *, int))ssl_sw[11].ptr)
#define SSL_CTX_use_certificate_file                                           \
   (*(int (*)(SSL_CTX *, const char *, int))ssl_sw[12].ptr)
#define SSL_CTX_set_default_passwd_cb                                          \
   (*(void (*)(SSL_CTX *, mg_callback_t))ssl_sw[13].ptr)
#define SSL_CTX_free (*(void (*)(SSL_CTX *))ssl_sw[14].ptr)
#define SSL_CTX_use_certificate_chain_file                                     \
   (*(int (*)(SSL_CTX *, const char *))ssl_sw[15].ptr)
#define TLS_client_method (*(SSL_METHOD * (*)(void)) ssl_sw[16].ptr)
#define SSL_pending (*(int (*)(SSL *))ssl_sw[17].ptr)
#define SSL_CTX_set_verify                                                     \
   (*(void (*)(SSL_CTX *,                                                     \
               int,                                                           \
               int (*verify_callback)(int, X509_STORE_CTX *)))ssl_sw[18]      \
         .ptr)
#define SSL_shutdown (*(int (*)(SSL *))ssl_sw[19].ptr)
#define SSL_CTX_load_verify_locations                                          \
   (*(int (*)(SSL_CTX *, const char *, const char *))ssl_sw[20].ptr)
#define SSL_CTX_set_default_verify_paths (*(int (*)(SSL_CTX *))ssl_sw[21].ptr)
#define SSL_CTX_set_verify_depth (*(void (*)(SSL_CTX *, int))ssl_sw[22].ptr)
#define SSL_get_peer_certificate (*(X509 * (*)(SSL *)) ssl_sw[23].ptr)
#define SSL_get_version (*(const char *(*)(SSL *))ssl_sw[24].ptr)
#define SSL_get_current_cipher (*(SSL_CIPHER * (*)(SSL *)) ssl_sw[25].ptr)
#define SSL_CIPHER_get_name                                                    \
   (*(const char *(*)(const SSL_CIPHER *))ssl_sw[26].ptr)
#define SSL_CTX_check_private_key (*(int (*)(SSL_CTX *))ssl_sw[27].ptr)
#define SSL_CTX_set_session_id_context                                         \
   (*(int (*)(SSL_CTX *, const unsigned char *, unsigned int))ssl_sw[28].ptr)
#define SSL_CTX_ctrl (*(long (*)(SSL_CTX *, int, long, void *))ssl_sw[29].ptr)
#define SSL_CTX_set_cipher_list                                                \
   (*(int (*)(SSL_CTX *, const char *))ssl_sw[30].ptr)
#define SSL_CTX_set_options                                                    \
   (*(unsigned long (*)(SSL_CTX *, unsigned long))ssl_sw[31].ptr)
#define SSL_CTX_set_info_callback                                              \
   (*(void (*)(SSL_CTX * ctx, void (*callback)(const SSL *, int, int)))       \
         ssl_sw[32]                                                           \
             .ptr)
#define SSL_get_ex_data (*(char *(*)(const SSL *, int))ssl_sw[33].ptr)
#define SSL_set_ex_data (*(void (*)(SSL *, int, char *))ssl_sw[34].ptr)
#define SSL_CTX_callback_ctrl                                                  \
   (*(long (*)(SSL_CTX *, int, void (*)(void)))ssl_sw[35].ptr)
#define SSL_get_servername                                                     \
   (*(const char *(*)(const SSL *, int type))ssl_sw[36].ptr)
#define SSL_set_SSL_CTX (*(SSL_CTX * (*)(SSL *, SSL_CTX *)) ssl_sw[37].ptr)
#define SSL_ctrl (*(long (*)(SSL *, int, long, void *))ssl_sw[38].ptr)

#define SSL_CTX_clear_options(ctx, op)                                         \
   SSL_CTX_ctrl((ctx), SSL_CTRL_CLEAR_OPTIONS, (op), NULL)
#define SSL_CTX_set_ecdh_auto(ctx, onoff)                                      \
   SSL_CTX_ctrl(ctx, SSL_CTRL_SET_ECDH_AUTO, onoff, NULL)

#define SSL_CTRL_SET_TLSEXT_SERVERNAME_CB 53
#define SSL_CTRL_SET_TLSEXT_SERVERNAME_ARG 54
#define SSL_CTRL_SET_TLSEXT_HOSTNAME 55
#define SSL_CTX_set_tlsext_servername_callback(ctx, cb)                        \
   SSL_CTX_callback_ctrl(ctx,                                                 \
                         SSL_CTRL_SET_TLSEXT_SERVERNAME_CB,                   \
                         (void (*)(void))cb)
#define SSL_CTX_set_tlsext_servername_arg(ctx, arg)                            \
   SSL_CTX_ctrl(ctx, SSL_CTRL_SET_TLSEXT_SERVERNAME_ARG, 0, (void *)arg)
#define SSL_set_tlsext_host_name(ctx, arg)                                     \
   SSL_ctrl(ctx, SSL_CTRL_SET_TLSEXT_HOSTNAME, 0, (void *)arg)

#define X509_get_notBefore(x) ((x)->cert_info->validity->notBefore)
#define X509_get_notAfter(x) ((x)->cert_info->validity->notAfter)

#define SSL_set_app_data(s, arg) (SSL_set_ex_data(s, 0, (char *)arg))
#define SSL_get_app_data(s) (SSL_get_ex_data(s, 0))

#define ERR_get_error (*(unsigned long (*)(void))crypto_sw[0].ptr)
#define ERR_error_string (*(char *(*)(unsigned long, char *))crypto_sw[1].ptr)
#define CONF_modules_unload (*(void (*)(int))crypto_sw[2].ptr)
#define X509_free (*(void (*)(X509 *))crypto_sw[3].ptr)
#define X509_get_subject_name (*(X509_NAME * (*)(X509 *)) crypto_sw[4].ptr)
#define X509_get_issuer_name (*(X509_NAME * (*)(X509 *)) crypto_sw[5].ptr)
#define X509_NAME_oneline                                                      \
   (*(char *(*)(X509_NAME *, char *, int))crypto_sw[6].ptr)
#define X509_get_serialNumber (*(ASN1_INTEGER * (*)(X509 *)) crypto_sw[7].ptr)
#define EVP_get_digestbyname                                                   \
   (*(const EVP_MD *(*)(const char *))crypto_sw[8].ptr)
#define EVP_Digest                                                             \
   (*(int (*)(                                                                \
       const void *, size_t, void *, unsigned int *, const EVP_MD *, void *)) \
         crypto_sw[9]                                                         \
             .ptr)
#define i2d_X509 (*(int (*)(X509 *, unsigned char **))crypto_sw[10].ptr)
#define BN_bn2hex (*(char *(*)(const BIGNUM *a))crypto_sw[11].ptr)
#define ASN1_INTEGER_to_BN                                                     \
   (*(BIGNUM * (*)(const ASN1_INTEGER *ai, BIGNUM *bn)) crypto_sw[12].ptr)
#define BN_free (*(void (*)(const BIGNUM *a))crypto_sw[13].ptr)
#define CRYPTO_free (*(void (*)(void *addr))crypto_sw[14].ptr)

#define OPENSSL_free(a) CRYPTO_free(a)

#define OPENSSL_REMOVE_THREAD_STATE()

/* init_ssl_ctx() function updates this array.
 * It loads SSL library dynamically and changes NULLs to the actual addresses
 * of respective functions. The macros above (like SSL_connect()) are really
 * just calling these functions indirectly via the pointer. */
static struct ssl_func ssl_sw[] = {{"SSL_free", NULL},
                                   {"SSL_accept", NULL},
                                   {"SSL_connect", NULL},
                                   {"SSL_read", NULL},
                                   {"SSL_write", NULL},
                                   {"SSL_get_error", NULL},
                                   {"SSL_set_fd", NULL},
                                   {"SSL_new", NULL},
                                   {"SSL_CTX_new", NULL},
                                   {"TLS_server_method", NULL},
                                   {"OPENSSL_init_ssl", NULL},
                                   {"SSL_CTX_use_PrivateKey_file", NULL},
                                   {"SSL_CTX_use_certificate_file", NULL},
                                   {"SSL_CTX_set_default_passwd_cb", NULL},
                                   {"SSL_CTX_free", NULL},
                                   {"SSL_CTX_use_certificate_chain_file", NULL},
                                   {"TLS_client_method", NULL},
                                   {"SSL_pending", NULL},
                                   {"SSL_CTX_set_verify", NULL},
                                   {"SSL_shutdown", NULL},
                                   {"SSL_CTX_load_verify_locations", NULL},
                                   {"SSL_CTX_set_default_verify_paths", NULL},
                                   {"SSL_CTX_set_verify_depth", NULL},
                                   {"SSL_get_peer_certificate", NULL},
                                   {"SSL_get_version", NULL},
                                   {"SSL_get_current_cipher", NULL},
                                   {"SSL_CIPHER_get_name", NULL},
                                   {"SSL_CTX_check_private_key", NULL},
                                   {"SSL_CTX_set_session_id_context", NULL},
                                   {"SSL_CTX_ctrl", NULL},
                                   {"SSL_CTX_set_cipher_list", NULL},
                                   {"SSL_CTX_set_options", NULL},
                                   {"SSL_CTX_set_info_callback", NULL},
                                   {"SSL_get_ex_data", NULL},
                                   {"SSL_set_ex_data", NULL},
                                   {"SSL_CTX_callback_ctrl", NULL},
                                   {"SSL_get_servername", NULL},
                                   {"SSL_set_SSL_CTX", NULL},
                                   {"SSL_ctrl", NULL},
                                   {NULL, NULL}};


/* Similar array as ssl_sw. These functions could be located in different
 * lib. */
static struct ssl_func crypto_sw[] = {{"ERR_get_error", NULL},
                                      {"ERR_error_string", NULL},
                                      {"CONF_modules_unload", NULL},
                                      {"X509_free", NULL},
                                      {"X509_get_subject_name", NULL},
                                      {"X509_get_issuer_name", NULL},
                                      {"X509_NAME_oneline", NULL},
                                      {"X509_get_serialNumber", NULL},
                                      {"EVP_get_digestbyname", NULL},
                                      {"EVP_Digest", NULL},
                                      {"i2d_X509", NULL},
                                      {"BN_bn2hex", NULL},
                                      {"ASN1_INTEGER_to_BN", NULL},
                                      {"BN_free", NULL},
                                      {"CRYPTO_free", NULL},
                                      {NULL, NULL}};
#else

#define SSL_free (*(void (*)(SSL *))ssl_sw[0].ptr)
#define SSL_accept (*(int (*)(SSL *))ssl_sw[1].ptr)
#define SSL_connect (*(int (*)(SSL *))ssl_sw[2].ptr)
#define SSL_read (*(int (*)(SSL *, void *, int))ssl_sw[3].ptr)
#define SSL_write (*(int (*)(SSL *, const void *, int))ssl_sw[4].ptr)
#define SSL_get_error (*(int (*)(SSL *, int))ssl_sw[5].ptr)
#define SSL_set_fd (*(int (*)(SSL *, SOCKET))ssl_sw[6].ptr)
#define SSL_new (*(SSL * (*)(SSL_CTX *)) ssl_sw[7].ptr)
#define SSL_CTX_new (*(SSL_CTX * (*)(SSL_METHOD *)) ssl_sw[8].ptr)
#define SSLv23_server_method (*(SSL_METHOD * (*)(void)) ssl_sw[9].ptr)
#define SSL_library_init (*(int (*)(void))ssl_sw[10].ptr)
#define SSL_CTX_use_PrivateKey_file                                            \
   (*(int (*)(SSL_CTX *, const char *, int))ssl_sw[11].ptr)
#define SSL_CTX_use_certificate_file                                           \
   (*(int (*)(SSL_CTX *, const char *, int))ssl_sw[12].ptr)
#define SSL_CTX_set_default_passwd_cb                                          \
   (*(void (*)(SSL_CTX *, mg_callback_t))ssl_sw[13].ptr)
#define SSL_CTX_free (*(void (*)(SSL_CTX *))ssl_sw[14].ptr)
#define SSL_load_error_strings (*(void (*)(void))ssl_sw[15].ptr)
#define SSL_CTX_use_certificate_chain_file                                     \
   (*(int (*)(SSL_CTX *, const char *))ssl_sw[16].ptr)
#define SSLv23_client_method (*(SSL_METHOD * (*)(void)) ssl_sw[17].ptr)
#define SSL_pending (*(int (*)(SSL *))ssl_sw[18].ptr)
#define SSL_CTX_set_verify                                                     \
   (*(void (*)(SSL_CTX *,                                                     \
               int,                                                           \
               int (*verify_callback)(int, X509_STORE_CTX *)))ssl_sw[19]      \
         .ptr)
#define SSL_shutdown (*(int (*)(SSL *))ssl_sw[20].ptr)
#define SSL_CTX_load_verify_locations                                          \
   (*(int (*)(SSL_CTX *, const char *, const char *))ssl_sw[21].ptr)
#define SSL_CTX_set_default_verify_paths (*(int (*)(SSL_CTX *))ssl_sw[22].ptr)
#define SSL_CTX_set_verify_depth (*(void (*)(SSL_CTX *, int))ssl_sw[23].ptr)
#define SSL_get_peer_certificate (*(X509 * (*)(SSL *)) ssl_sw[24].ptr)
#define SSL_get_version (*(const char *(*)(SSL *))ssl_sw[25].ptr)
#define SSL_get_current_cipher (*(SSL_CIPHER * (*)(SSL *)) ssl_sw[26].ptr)
#define SSL_CIPHER_get_name                                                    \
   (*(const char *(*)(const SSL_CIPHER *))ssl_sw[27].ptr)
#define SSL_CTX_check_private_key (*(int (*)(SSL_CTX *))ssl_sw[28].ptr)
#define SSL_CTX_set_session_id_context                                         \
   (*(int (*)(SSL_CTX *, const unsigned char *, unsigned int))ssl_sw[29].ptr)
#define SSL_CTX_ctrl (*(long (*)(SSL_CTX *, int, long, void *))ssl_sw[30].ptr)
#define SSL_CTX_set_cipher_list                                                \
   (*(int (*)(SSL_CTX *, const char *))ssl_sw[31].ptr)
#define SSL_CTX_set_info_callback                                              \
   (*(void (*)(SSL_CTX *, void (*callback)(const SSL *, int, int)))ssl_sw[32] \
         .ptr)
#define SSL_get_ex_data (*(char *(*)(const SSL *, int))ssl_sw[33].ptr)
#define SSL_set_ex_data (*(void (*)(SSL *, int, char *))ssl_sw[34].ptr)
#define SSL_CTX_callback_ctrl                                                  \
   (*(long (*)(SSL_CTX *, int, void (*)(void)))ssl_sw[35].ptr)
#define SSL_get_servername                                                     \
   (*(const char *(*)(const SSL *, int type))ssl_sw[36].ptr)
#define SSL_set_SSL_CTX (*(SSL_CTX * (*)(SSL *, SSL_CTX *)) ssl_sw[37].ptr)
#define SSL_ctrl (*(long (*)(SSL *, int, long, void *))ssl_sw[38].ptr)

#define SSL_CTX_set_options(ctx, op)                                           \
   SSL_CTX_ctrl((ctx), SSL_CTRL_OPTIONS, (op), NULL)
#define SSL_CTX_clear_options(ctx, op)                                         \
   SSL_CTX_ctrl((ctx), SSL_CTRL_CLEAR_OPTIONS, (op), NULL)
#define SSL_CTX_set_ecdh_auto(ctx, onoff)                                      \
   SSL_CTX_ctrl(ctx, SSL_CTRL_SET_ECDH_AUTO, onoff, NULL)

#define SSL_CTRL_SET_TLSEXT_SERVERNAME_CB 53
#define SSL_CTRL_SET_TLSEXT_SERVERNAME_ARG 54
#define SSL_CTRL_SET_TLSEXT_HOSTNAME 55
#define SSL_CTX_set_tlsext_servername_callback(ctx, cb)                        \
   SSL_CTX_callback_ctrl(ctx,                                                 \
                         SSL_CTRL_SET_TLSEXT_SERVERNAME_CB,                   \
                         (void (*)(void))cb)
#define SSL_CTX_set_tlsext_servername_arg(ctx, arg)                            \
   SSL_CTX_ctrl(ctx, SSL_CTRL_SET_TLSEXT_SERVERNAME_ARG, 0, (void *)arg)
#define SSL_set_tlsext_host_name(ctx, arg)                                     \
   SSL_ctrl(ctx, SSL_CTRL_SET_TLSEXT_HOSTNAME, 0, (void *)arg)

#define X509_get_notBefore(x) ((x)->cert_info->validity->notBefore)
#define X509_get_notAfter(x) ((x)->cert_info->validity->notAfter)

#define SSL_set_app_data(s, arg) (SSL_set_ex_data(s, 0, (char *)arg))
#define SSL_get_app_data(s) (SSL_get_ex_data(s, 0))

#define CRYPTO_num_locks (*(int (*)(void))crypto_sw[0].ptr)
#define CRYPTO_set_locking_callback                                            \
   (*(void (*)(void (*)(int, int, const char *, int)))crypto_sw[1].ptr)
#define CRYPTO_set_id_callback                                                 \
   (*(void (*)(unsigned long (*)(void)))crypto_sw[2].ptr)
#define ERR_get_error (*(unsigned long (*)(void))crypto_sw[3].ptr)
#define ERR_error_string (*(char *(*)(unsigned long, char *))crypto_sw[4].ptr)
#define ERR_remove_state (*(void (*)(unsigned long))crypto_sw[5].ptr)
#define ERR_free_strings (*(void (*)(void))crypto_sw[6].ptr)
#define ENGINE_cleanup (*(void (*)(void))crypto_sw[7].ptr)
#define CONF_modules_unload (*(void (*)(int))crypto_sw[8].ptr)
#define CRYPTO_cleanup_all_ex_data (*(void (*)(void))crypto_sw[9].ptr)
#define EVP_cleanup (*(void (*)(void))crypto_sw[10].ptr)
#define X509_free (*(void (*)(X509 *))crypto_sw[11].ptr)
#define X509_get_subject_name (*(X509_NAME * (*)(X509 *)) crypto_sw[12].ptr)
#define X509_get_issuer_name (*(X509_NAME * (*)(X509 *)) crypto_sw[13].ptr)
#define X509_NAME_oneline                                                      \
   (*(char *(*)(X509_NAME *, char *, int))crypto_sw[14].ptr)
#define X509_get_serialNumber (*(ASN1_INTEGER * (*)(X509 *)) crypto_sw[15].ptr)
#define i2c_ASN1_INTEGER                                                       \
   (*(int (*)(ASN1_INTEGER *, unsigned char **))crypto_sw[16].ptr)
#define EVP_get_digestbyname                                                   \
   (*(const EVP_MD *(*)(const char *))crypto_sw[17].ptr)
#define EVP_Digest                                                             \
   (*(int (*)(                                                                \
       const void *, size_t, void *, unsigned int *, const EVP_MD *, void *)) \
         crypto_sw[18]                                                        \
             .ptr)
#define i2d_X509 (*(int (*)(X509 *, unsigned char **))crypto_sw[19].ptr)
#define BN_bn2hex (*(char *(*)(const BIGNUM *a))crypto_sw[20].ptr)
#define ASN1_INTEGER_to_BN                                                     \
   (*(BIGNUM * (*)(const ASN1_INTEGER *ai, BIGNUM *bn)) crypto_sw[21].ptr)
#define BN_free (*(void (*)(const BIGNUM *a))crypto_sw[22].ptr)
#define CRYPTO_free (*(void (*)(void *addr))crypto_sw[23].ptr)

#define OPENSSL_free(a) CRYPTO_free(a)

/* use here ERR_remove_state,
 * while on some platforms function is not included into library due to
 * deprication */
#define OPENSSL_REMOVE_THREAD_STATE() ERR_remove_state(0)

/* init_ssl_ctx() function updates this array.
 * It loads SSL library dynamically and changes NULLs to the actual addresses
 * of respective functions. The macros above (like SSL_connect()) are really
 * just calling these functions indirectly via the pointer. */
static struct ssl_func ssl_sw[] = {{"SSL_free", NULL},
                                   {"SSL_accept", NULL},
                                   {"SSL_connect", NULL},
                                   {"SSL_read", NULL},
                                   {"SSL_write", NULL},
                                   {"SSL_get_error", NULL},
                                   {"SSL_set_fd", NULL},
                                   {"SSL_new", NULL},
                                   {"SSL_CTX_new", NULL},
                                   {"SSLv23_server_method", NULL},
                                   {"SSL_library_init", NULL},
                                   {"SSL_CTX_use_PrivateKey_file", NULL},
                                   {"SSL_CTX_use_certificate_file", NULL},
                                   {"SSL_CTX_set_default_passwd_cb", NULL},
                                   {"SSL_CTX_free", NULL},
                                   {"SSL_load_error_strings", NULL},
                                   {"SSL_CTX_use_certificate_chain_file", NULL},
                                   {"SSLv23_client_method", NULL},
                                   {"SSL_pending", NULL},
                                   {"SSL_CTX_set_verify", NULL},
                                   {"SSL_shutdown", NULL},
                                   {"SSL_CTX_load_verify_locations", NULL},
                                   {"SSL_CTX_set_default_verify_paths", NULL},
                                   {"SSL_CTX_set_verify_depth", NULL},
                                   {"SSL_get_peer_certificate", NULL},
                                   {"SSL_get_version", NULL},
                                   {"SSL_get_current_cipher", NULL},
                                   {"SSL_CIPHER_get_name", NULL},
                                   {"SSL_CTX_check_private_key", NULL},
                                   {"SSL_CTX_set_session_id_context", NULL},
                                   {"SSL_CTX_ctrl", NULL},
                                   {"SSL_CTX_set_cipher_list", NULL},
                                   {"SSL_CTX_set_info_callback", NULL},
                                   {"SSL_get_ex_data", NULL},
                                   {"SSL_set_ex_data", NULL},
                                   {"SSL_CTX_callback_ctrl", NULL},
                                   {"SSL_get_servername", NULL},
                                   {"SSL_set_SSL_CTX", NULL},
                                   {"SSL_ctrl", NULL},
                                   {NULL, NULL}};


/* Similar array as ssl_sw. These functions could be located in different
 * lib. */
static struct ssl_func crypto_sw[] = {{"CRYPTO_num_locks", NULL},
                                      {"CRYPTO_set_locking_callback", NULL},
                                      {"CRYPTO_set_id_callback", NULL},
                                      {"ERR_get_error", NULL},
                                      {"ERR_error_string", NULL},
                                      {"ERR_remove_state", NULL},
                                      {"ERR_free_strings", NULL},
                                      {"ENGINE_cleanup", NULL},
                                      {"CONF_modules_unload", NULL},
                                      {"CRYPTO_cleanup_all_ex_data", NULL},
                                      {"EVP_cleanup", NULL},
                                      {"X509_free", NULL},
                                      {"X509_get_subject_name", NULL},
                                      {"X509_get_issuer_name", NULL},
                                      {"X509_NAME_oneline", NULL},
                                      {"X509_get_serialNumber", NULL},
                                      {"i2c_ASN1_INTEGER", NULL},
                                      {"EVP_get_digestbyname", NULL},
                                      {"EVP_Digest", NULL},
                                      {"i2d_X509", NULL},
                                      {"BN_bn2hex", NULL},
                                      {"ASN1_INTEGER_to_BN", NULL},
                                      {"BN_free", NULL},
                                      {"CRYPTO_free", NULL},
                                      {NULL, NULL}};
#endif /* OPENSSL_API_1_1 */
#endif /* NO_SSL_DL */
#endif /* NO_SSL */


#if !defined(NO_CACHING)
static const char *month_names[] = {"Jan",
                                    "Feb",
                                    "Mar",
                                    "Apr",
                                    "May",
                                    "Jun",
                                    "Jul",
                                    "Aug",
                                    "Sep",
                                    "Oct",
                                    "Nov",
                                    "Dec"};
#endif /* !NO_CACHING */

/* Unified socket address. For IPv6 support, add IPv6 address structure in
 * the
 * union u. */
union usa {
   struct sockaddr sa;
   struct sockaddr_in sin;
#if defined(USE_IPV6)
   struct sockaddr_in6 sin6;
#endif
};

/* Describes a string (chunk of memory). */
struct vec {
   const char *ptr;
   size_t len;
};

struct mg_file_stat {
   /* File properties filled by mg_stat: */
   uint64_t size;
   time_t last_modified;
   int is_directory; /* Set to 1 if mg_stat is called for a directory */
   int is_gzipped;   /* Set to 1 if the content is gzipped, in which
                      * case we need a "Content-Eencoding: gzip" header */
   int location;     /* 0 = nowhere, 1 = on disk, 2 = in memory */
};

struct mg_file_in_memory {
   char *p;
   uint32_t pos;
   char mode;
};

struct mg_file_access {
   /* File properties filled by mg_fopen: */
   FILE *fp;
#if defined(MG_USE_OPEN_FILE)
   /* TODO (low): Remove obsolete "file in memory" implementation.
    * In an "early 2017" discussion at Google groups
    * https://groups.google.com/forum/#!topic/civetweb/h9HT4CmeYqI
    * we decided to get rid of this feature (after some fade-out
    * phase). */
   const char *membuf;
#endif
};

struct mg_file {
   struct mg_file_stat stat;
   struct mg_file_access access;
};

#if defined(MG_USE_OPEN_FILE)

#define STRUCT_FILE_INITIALIZER                                                \
   {                                                                          \
      {(uint64_t)0, (time_t)0, 0, 0, 0},                                     \
      {                                                                      \
         (FILE *)NULL, (const char *)NULL                                   \
      }                                                                      \
   }

#else

#define STRUCT_FILE_INITIALIZER                                                \
   {                                                                          \
      {(uint64_t)0, (time_t)0, 0, 0, 0},                                     \
      {                                                                      \
         (FILE *)NULL                                                       \
      }                                                                      \
   }

#endif


/* Describes listening socket, or socket which was accept()-ed by the master
 * thread and queued for future handling by the worker thread. */
struct socket {
   SOCKET sock;             /* Listening socket */
   union usa lsa;           /* Local socket address */
   union usa rsa;           /* Remote socket address */
   unsigned char is_ssl;    /* Is port SSL-ed */
   unsigned char ssl_redir; /* Is port supposed to redirect everything to SSL
                             * port */
   unsigned char in_use;    /* Is valid */
};


/* Enum const for all options must be in sync with
 * static struct mg_option config_options[]
 * This is tested in the unit test (test/private.c)
 * "Private Config Options"
 */
enum {
   /* Once for each server */
   LISTENING_PORTS,
   NUM_THREADS,
   RUN_AS_USER,
   CONFIG_TCP_NODELAY, /* Prepended CONFIG_ to avoid conflict with the
                        * socket option typedef TCP_NODELAY. */
   MAX_REQUEST_SIZE,
   LINGER_TIMEOUT,
#if defined(__linux__)
   ALLOW_SENDFILE_CALL,
#endif
#if defined(_WIN32)
   CASE_SENSITIVE_FILES,
#endif
   THROTTLE,
   ACCESS_LOG_FILE,
   ERROR_LOG_FILE,
   ENABLE_KEEP_ALIVE,
   REQUEST_TIMEOUT,
   KEEP_ALIVE_TIMEOUT,
#if defined(USE_WEBSOCKET)
   WEBSOCKET_TIMEOUT,
   ENABLE_WEBSOCKET_PING_PONG,
#endif
   DECODE_URL,
#if defined(USE_LUA)
   LUA_BACKGROUND_SCRIPT,
   LUA_BACKGROUND_SCRIPT_PARAMS,
#endif
#if defined(USE_TIMERS)
   CGI_TIMEOUT,
#endif

   /* Once for each domain */
   DOCUMENT_ROOT,
   CGI_EXTENSIONS,
   CGI_ENVIRONMENT,
   PUT_DELETE_PASSWORDS_FILE,
   CGI_INTERPRETER,
   PROTECT_URI,
   AUTHENTICATION_DOMAIN,
   ENABLE_AUTH_DOMAIN_CHECK,
   SSI_EXTENSIONS,
   ENABLE_DIRECTORY_LISTING,
   GLOBAL_PASSWORDS_FILE,
   INDEX_FILES,
   ACCESS_CONTROL_LIST,
   EXTRA_MIME_TYPES,
   SSL_CERTIFICATE,
   SSL_CERTIFICATE_CHAIN,
   URL_REWRITE_PATTERN,
   HIDE_FILES,
   SSL_DO_VERIFY_PEER,
   SSL_CA_PATH,
   SSL_CA_FILE,
   SSL_VERIFY_DEPTH,
   SSL_DEFAULT_VERIFY_PATHS,
   SSL_CIPHER_LIST,
   SSL_PROTOCOL_VERSION,
   SSL_SHORT_TRUST,

#if defined(USE_LUA)
   LUA_PRELOAD_FILE,
   LUA_SCRIPT_EXTENSIONS,
   LUA_SERVER_PAGE_EXTENSIONS,
#if defined(MG_EXPERIMENTAL_INTERFACES)
   LUA_DEBUG_PARAMS,
#endif
#endif
#if defined(USE_DUKTAPE)
   DUKTAPE_SCRIPT_EXTENSIONS,
#endif

#if defined(USE_WEBSOCKET)
   WEBSOCKET_ROOT,
#endif
#if defined(USE_LUA) && defined(USE_WEBSOCKET)
   LUA_WEBSOCKET_EXTENSIONS,
#endif

   ACCESS_CONTROL_ALLOW_ORIGIN,
   ACCESS_CONTROL_ALLOW_METHODS,
   ACCESS_CONTROL_ALLOW_HEADERS,
   ERROR_PAGES,
#if !defined(NO_CACHING)
   STATIC_FILE_MAX_AGE,
#endif
#if !defined(NO_SSL)
   STRICT_HTTPS_MAX_AGE,
#endif
   ADDITIONAL_HEADER,
   ALLOW_INDEX_SCRIPT_SUB_RES,

   NUM_OPTIONS
};


/* Config option name, config types, default value.
 * Must be in the same order as the enum const above.
 */
static const struct mg_option config_options[] = {

    /* Once for each server */
    {"listening_ports", MG_CONFIG_TYPE_STRING_LIST, "8080"},
    {"num_threads", MG_CONFIG_TYPE_NUMBER, "50"},
    {"run_as_user", MG_CONFIG_TYPE_STRING, NULL},
    {"tcp_nodelay", MG_CONFIG_TYPE_NUMBER, "0"},
    {"max_request_size", MG_CONFIG_TYPE_NUMBER, "16384"},
    {"linger_timeout_ms", MG_CONFIG_TYPE_NUMBER, NULL},
#if defined(__linux__)
    {"allow_sendfile_call", MG_CONFIG_TYPE_BOOLEAN, "yes"},
#endif
#if defined(_WIN32)
    {"case_sensitive", MG_CONFIG_TYPE_BOOLEAN, "no"},
#endif
    {"throttle", MG_CONFIG_TYPE_STRING_LIST, NULL},
    {"access_log_file", MG_CONFIG_TYPE_FILE, NULL},
    {"error_log_file", MG_CONFIG_TYPE_FILE, NULL},
    {"enable_keep_alive", MG_CONFIG_TYPE_BOOLEAN, "no"},
    {"request_timeout_ms", MG_CONFIG_TYPE_NUMBER, "30000"},
    {"keep_alive_timeout_ms", MG_CONFIG_TYPE_NUMBER, "500"},
#if defined(USE_WEBSOCKET)
    {"websocket_timeout_ms", MG_CONFIG_TYPE_NUMBER, NULL},
    {"enable_websocket_ping_pong", MG_CONFIG_TYPE_BOOLEAN, "no"},
#endif
    {"decode_url", MG_CONFIG_TYPE_BOOLEAN, "yes"},
#if defined(USE_LUA)
    {"lua_background_script", MG_CONFIG_TYPE_FILE, NULL},
    {"lua_background_script_params", MG_CONFIG_TYPE_STRING_LIST, NULL},
#endif
#if defined(USE_TIMERS)
    {"cgi_timeout_ms", MG_CONFIG_TYPE_NUMBER, NULL},
#endif

    /* Once for each domain */
    {"document_root", MG_CONFIG_TYPE_DIRECTORY, NULL},
    {"cgi_pattern", MG_CONFIG_TYPE_EXT_PATTERN, "**.cgi$|**.pl$|**.php$"},
    {"cgi_environment", MG_CONFIG_TYPE_STRING_LIST, NULL},
    {"put_delete_auth_file", MG_CONFIG_TYPE_FILE, NULL},
    {"cgi_interpreter", MG_CONFIG_TYPE_FILE, NULL},
    {"protect_uri", MG_CONFIG_TYPE_STRING_LIST, NULL},
    {"authentication_domain", MG_CONFIG_TYPE_STRING, "mydomain.com"},
    {"enable_auth_domain_check", MG_CONFIG_TYPE_BOOLEAN, "yes"},
    {"ssi_pattern", MG_CONFIG_TYPE_EXT_PATTERN, "**.shtml$|**.shtm$"},
    {"enable_directory_listing", MG_CONFIG_TYPE_BOOLEAN, "yes"},
    {"global_auth_file", MG_CONFIG_TYPE_FILE, NULL},
    {"index_files",
     MG_CONFIG_TYPE_STRING_LIST,
#if defined(USE_LUA)
     "index.xhtml,index.html,index.htm,"
     "index.lp,index.lsp,index.lua,index.cgi,"
     "index.shtml,index.php"},
#else
     "index.xhtml,index.html,index.htm,index.cgi,index.shtml,index.php"},
#endif
    {"access_control_list", MG_CONFIG_TYPE_STRING_LIST, NULL},
    {"extra_mime_types", MG_CONFIG_TYPE_STRING_LIST, NULL},
    {"ssl_certificate", MG_CONFIG_TYPE_FILE, NULL},
    {"ssl_certificate_chain", MG_CONFIG_TYPE_FILE, NULL},
    {"url_rewrite_patterns", MG_CONFIG_TYPE_STRING_LIST, NULL},
    {"hide_files_patterns", MG_CONFIG_TYPE_EXT_PATTERN, NULL},

    {"ssl_verify_peer", MG_CONFIG_TYPE_YES_NO_OPTIONAL, "no"},

    {"ssl_ca_path", MG_CONFIG_TYPE_DIRECTORY, NULL},
    {"ssl_ca_file", MG_CONFIG_TYPE_FILE, NULL},
    {"ssl_verify_depth", MG_CONFIG_TYPE_NUMBER, "9"},
    {"ssl_default_verify_paths", MG_CONFIG_TYPE_BOOLEAN, "yes"},
    {"ssl_cipher_list", MG_CONFIG_TYPE_STRING, NULL},
    {"ssl_protocol_version", MG_CONFIG_TYPE_NUMBER, "0"},
    {"ssl_short_trust", MG_CONFIG_TYPE_BOOLEAN, "no"},

#if defined(USE_LUA)
    {"lua_preload_file", MG_CONFIG_TYPE_FILE, NULL},
    {"lua_script_pattern", MG_CONFIG_TYPE_EXT_PATTERN, "**.lua$"},
    {"lua_server_page_pattern", MG_CONFIG_TYPE_EXT_PATTERN, "**.lp$|**.lsp$"},
#if defined(MG_EXPERIMENTAL_INTERFACES)
    {"lua_debug", MG_CONFIG_TYPE_STRING, NULL},
#endif
#endif
#if defined(USE_DUKTAPE)
    /* The support for duktape is still in alpha version state.
     * The name of this config option might change. */
    {"duktape_script_pattern", MG_CONFIG_TYPE_EXT_PATTERN, "**.ssjs$"},
#endif

#if defined(USE_WEBSOCKET)
    {"websocket_root", MG_CONFIG_TYPE_DIRECTORY, NULL},
#endif
#if defined(USE_LUA) && defined(USE_WEBSOCKET)
    {"lua_websocket_pattern", MG_CONFIG_TYPE_EXT_PATTERN, "**.lua$"},
#endif
    {"access_control_allow_origin", MG_CONFIG_TYPE_STRING, "*"},
    {"access_control_allow_methods", MG_CONFIG_TYPE_STRING, "*"},
    {"access_control_allow_headers", MG_CONFIG_TYPE_STRING, "*"},
    {"error_pages", MG_CONFIG_TYPE_DIRECTORY, NULL},
#if !defined(NO_CACHING)
    {"static_file_max_age", MG_CONFIG_TYPE_NUMBER, "3600"},
#endif
#if !defined(NO_SSL)
    {"strict_transport_security_max_age", MG_CONFIG_TYPE_NUMBER, NULL},
#endif
    {"additional_header", MG_CONFIG_TYPE_STRING_MULTILINE, NULL},
    {"allow_index_script_resource", MG_CONFIG_TYPE_BOOLEAN, "no"},

    {NULL, MG_CONFIG_TYPE_UNKNOWN, NULL}};


/* Check if the config_options and the corresponding enum have compatible
 * sizes. */
mg_static_assert((sizeof(config_options) / sizeof(config_options[0]))
                     == (NUM_OPTIONS + 1),
                 "config_options and enum not sync");


enum { REQUEST_HANDLER, WEBSOCKET_HANDLER, AUTH_HANDLER };


struct mg_handler_info {
   /* Name/Pattern of the URI. */
   char *uri;
   size_t uri_len;

   /* handler type */
   int handler_type;

   /* Handler for http/https or authorization requests. */
   mg_request_handler handler;
   unsigned int refcount;
   pthread_mutex_t refcount_mutex; /* Protects refcount */
   pthread_cond_t
       refcount_cond; /* Signaled when handler refcount is decremented */

   /* Handler for ws/wss (websocket) requests. */
   mg_websocket_connect_handler connect_handler;
   mg_websocket_ready_handler ready_handler;
   mg_websocket_data_handler data_handler;
   mg_websocket_close_handler close_handler;

   /* accepted subprotocols for ws/wss requests. */
   struct mg_websocket_subprotocols *subprotocols;

   /* Handler for authorization requests */
   mg_authorization_handler auth_handler;

   /* User supplied argument for the handler function. */
   void *cbdata;

   /* next handler in a linked list */
   struct mg_handler_info *next;
};


enum {
   CONTEXT_INVALID,
   CONTEXT_SERVER,
   CONTEXT_HTTP_CLIENT,
   CONTEXT_WS_CLIENT
};


struct mg_domain_context {
   SSL_CTX *ssl_ctx;                 /* SSL context */
   char *config[NUM_OPTIONS];        /* Civetweb configuration parameters */
   struct mg_handler_info *handlers; /* linked list of uri handlers */

   /* Server nonce */
   uint64_t auth_nonce_mask;  /* Mask for all nonce values */
   unsigned long nonce_count; /* Used nonces, used for authentication */

#if defined(USE_LUA) && defined(USE_WEBSOCKET)
   /* linked list of shared lua websockets */
   struct mg_shared_lua_websocket_list *shared_lua_websockets;
#endif

   /* Linked list of domains */
   struct mg_domain_context *next;
};


struct mg_context {

   /* Part 1 - Physical context:
    * This holds threads, ports, timeouts, ...
    * set for the entire server, independent from the
    * addressed hostname.
    */

   /* Connection related */
   int context_type; /* See CONTEXT_* above */

   struct socket *listening_sockets;
   struct pollfd *listening_socket_fds;
   unsigned int num_listening_sockets;

   struct mg_connection *worker_connections; /* The connection struct, pre-
                                              * allocated for each worker */

#if defined(USE_SERVER_STATS)
   int active_connections;
   int max_connections;
   int64_t total_connections;
   int64_t total_requests;
   int64_t total_data_read;
   int64_t total_data_written;
#endif

   /* Thread related */
   volatile int stop_flag;       /* Should we stop event loop */
   pthread_mutex_t thread_mutex; /* Protects (max|num)_threads */

   pthread_t masterthreadid; /* The master thread ID */
   unsigned int
       cfg_worker_threads;      /* The number of configured worker threads. */
   pthread_t *worker_threadids; /* The worker thread IDs */

/* Connection to thread dispatching */
#if defined(ALTERNATIVE_QUEUE)
   struct socket *client_socks;
   void **client_wait_events;
#else
   struct socket queue[MGSQLEN]; /* Accepted sockets */
   volatile int sq_head;         /* Head of the socket queue */
   volatile int sq_tail;         /* Tail of the socket queue */
   pthread_cond_t sq_full;       /* Signaled when socket is produced */
   pthread_cond_t sq_empty;      /* Signaled when socket is consumed */
#endif

   /* Memory related */
   unsigned int max_request_size; /* The max request size */

#if defined(USE_SERVER_STATS)
   struct mg_memory_stat ctx_memory;
#endif

   /* Operating system related */
   char *systemName;  /* What operating system is running */
   time_t start_time; /* Server start time, used for authentication
                       * and for diagnstics. */

#if defined(USE_TIMERS)
   struct ttimers *timers;
#endif

/* Lua specific: Background operations and shared websockets */
#if defined(USE_LUA)
   void *lua_background_state;
#endif

   /* Server nonce */
   pthread_mutex_t nonce_mutex; /* Protects nonce_count */

   /* Server callbacks */
   struct mg_callbacks callbacks; /* User-defined callback function */
   void *user_data;               /* User-defined data */

   /* Part 2 - Logical domain:
    * This holds hostname, TLS certificate, document root, ...
    * set for a domain hosted at the server.
    * There may be multiple domains hosted at one physical server.
    * The default domain "dd" is the first element of a list of
    * domains.
    */
   struct mg_domain_context dd; /* default domain */
};


#if defined(USE_SERVER_STATS)
static struct mg_memory_stat mg_common_memory = {0, 0, 0};

static struct mg_memory_stat *
get_memory_stat(struct mg_context *ctx)
{
   if (ctx) {
      return &(ctx->ctx_memory);
   }
   return &mg_common_memory;
}
#endif

enum {
   CONNECTION_TYPE_INVALID,
   CONNECTION_TYPE_REQUEST,
   CONNECTION_TYPE_RESPONSE
};

struct mg_connection {
   int connection_type; /* see CONNECTION_TYPE_* above */

   struct mg_request_info request_info;
   struct mg_response_info response_info;

   struct mg_context *phys_ctx;
   struct mg_domain_context *dom_ctx;

#if defined(USE_SERVER_STATS)
   int conn_state; /* 0 = undef, numerical value may change in different
                    * versions. For the current definition, see
                    * mg_get_connection_info_impl */
#endif

   const char *host;         /* Host (HTTP/1.1 header or SNI) */
   SSL *ssl;                 /* SSL descriptor */
   SSL_CTX *client_ssl_ctx;  /* SSL context for client connections */
   struct socket client;     /* Connected client */
   time_t conn_birth_time;   /* Time (wall clock) when connection was
                              * established */
   struct timespec req_time; /* Time (since system start) when the request
                              * was received */
   int64_t num_bytes_sent;   /* Total bytes sent to client */
   int64_t content_len;      /* Content-Length header value */
   int64_t consumed_content; /* How many bytes of content have been read */
   int is_chunked;           /* Transfer-Encoding is chunked:
                              * 0 = not chunked,
                              * 1 = chunked, do data read yet,
                              * 2 = chunked, some data read,
                              * 3 = chunked, all data read
                              */
   size_t chunk_remainder;   /* Unread data from the last chunk */
   char *buf;                /* Buffer for received data */
   char *path_info;          /* PATH_INFO part of the URL */

   int must_close;       /* 1 if connection must be closed */
   int accept_gzip;      /* 1 if gzip encoding is accepted */
   int in_error_handler; /* 1 if in handler for user defined error
                          * pages */
#if defined(USE_WEBSOCKET)
   int in_websocket_handling; /* 1 if in read_websocket */
#endif
   int handled_requests; /* Number of requests handled by this connection
                          */
   int buf_size;         /* Buffer size */
   int request_len;      /* Size of the request + headers in a buffer */
   int data_len;         /* Total size of data in a buffer */
   int status_code;      /* HTTP reply status code, e.g. 200 */
   int throttle;         /* Throttling, bytes/sec. <= 0 means no
                          * throttle */

   time_t last_throttle_time;   /* Last time throttled data was sent */
   int64_t last_throttle_bytes; /* Bytes sent this second */
   pthread_mutex_t mutex;       /* Used by mg_(un)lock_connection to ensure
                                 * atomic transmissions for websockets */
#if defined(USE_LUA) && defined(USE_WEBSOCKET)
   void *lua_websocket_state; /* Lua_State for a websocket connection */
#endif

   int thread_index; /* Thread index within ctx */
};


/* Directory entry */
struct de {
   struct mg_connection *conn;
   char *file_name;
   struct mg_file_stat file;
};


#if defined(USE_WEBSOCKET)
static int is_websocket_protocol(const struct mg_connection *conn);
#else
#define is_websocket_protocol(conn) (0)
#endif


#define mg_cry_internal(conn, fmt, ...)                                        \
   mg_cry_internal_wrap(conn, __func__, __LINE__, fmt, __VA_ARGS__)

static void mg_cry_internal_wrap(const struct mg_connection *conn,
                                 const char *func,
                                 unsigned line,
                                 const char *fmt,
                                 ...) PRINTF_ARGS(4, 5);


#if !defined(NO_THREAD_NAME)
#if defined(_WIN32) && defined(_MSC_VER)
/* Set the thread name for debugging purposes in Visual Studio
 * http://msdn.microsoft.com/en-us/library/xcb2z8hs.aspx
 */
#pragma pack(push, 8)
typedef struct tagTHREADNAME_INFO {
   DWORD dwType;     /* Must be 0x1000. */
   LPCSTR szName;    /* Pointer to name (in user addr space). */
   DWORD dwThreadID; /* Thread ID (-1=caller thread). */
   DWORD dwFlags;    /* Reserved for future use, must be zero. */
} THREADNAME_INFO;
#pragma pack(pop)

#elif defined(__linux__)

#include <sys/prctl.h>
#include <sys/sendfile.h>
#if defined(ALTERNATIVE_QUEUE)
#include <sys/eventfd.h>
#endif /* ALTERNATIVE_QUEUE */


#if defined(ALTERNATIVE_QUEUE)

static void *
event_create(void)
{
   int evhdl = eventfd(0, EFD_CLOEXEC);
   int *ret;

   if (evhdl == -1) {
      /* Linux uses -1 on error, Windows NULL. */
      /* However, Linux does not return 0 on success either. */
      return 0;
   }

   ret = (int *)mg_malloc(sizeof(int));
   if (ret) {
      *ret = evhdl;
   } else {
      (void)close(evhdl);
   }

   return (void *)ret;
}


static int
event_wait(void *eventhdl)
{
   uint64_t u;
   int evhdl, s;

   if (!eventhdl) {
      /* error */
      return 0;
   }
   evhdl = *(int *)eventhdl;

   s = (int)read(evhdl, &u, sizeof(u));
   if (s != sizeof(u)) {
      /* error */
      return 0;
   }
   (void)u; /* the value is not required */
   return 1;
}


static int
event_signal(void *eventhdl)
{
   uint64_t u = 1;
   int evhdl, s;

   if (!eventhdl) {
      /* error */
      return 0;
   }
   evhdl = *(int *)eventhdl;

   s = (int)write(evhdl, &u, sizeof(u));
   if (s != sizeof(u)) {
      /* error */
      return 0;
   }
   return 1;
}


static void
event_destroy(void *eventhdl)
{
   int evhdl;

   if (!eventhdl) {
      /* error */
      return;
   }
   evhdl = *(int *)eventhdl;

   close(evhdl);
   mg_free(eventhdl);
}


#endif

#endif


#if !defined(__linux__) && !defined(_WIN32) && defined(ALTERNATIVE_QUEUE)

struct posix_event {
   pthread_mutex_t mutex;
   pthread_cond_t cond;
};


static void *
event_create(void)
{
   struct posix_event *ret = mg_malloc(sizeof(struct posix_event));
   if (ret == 0) {
      /* out of memory */
      return 0;
   }
   if (0 != pthread_mutex_init(&(ret->mutex), NULL)) {
      /* pthread mutex not available */
      mg_free(ret);
      return 0;
   }
   if (0 != pthread_cond_init(&(ret->cond), NULL)) {
      /* pthread cond not available */
      pthread_mutex_destroy(&(ret->mutex));
      mg_free(ret);
      return 0;
   }
   return (void *)ret;
}


static int
event_wait(void *eventhdl)
{
   struct posix_event *ev = (struct posix_event *)eventhdl;
   pthread_mutex_lock(&(ev->mutex));
   pthread_cond_wait(&(ev->cond), &(ev->mutex));
   pthread_mutex_unlock(&(ev->mutex));
   return 1;
}


static int
event_signal(void *eventhdl)
{
   struct posix_event *ev = (struct posix_event *)eventhdl;
   pthread_mutex_lock(&(ev->mutex));
   pthread_cond_signal(&(ev->cond));
   pthread_mutex_unlock(&(ev->mutex));
   return 1;
}


static void
event_destroy(void *eventhdl)
{
   struct posix_event *ev = (struct posix_event *)eventhdl;
   pthread_cond_destroy(&(ev->cond));
   pthread_mutex_destroy(&(ev->mutex));
   mg_free(ev);
}
#endif


static void
mg_set_thread_name(const char *name)
{
   char threadName[16 + 1]; /* 16 = Max. thread length in Linux/OSX/.. */

   mg_snprintf(
       NULL, NULL, threadName, sizeof(threadName), "civetweb-%s", name);

#if defined(_WIN32)
#if defined(_MSC_VER)
   /* Windows and Visual Studio Compiler */
   __try {
      THREADNAME_INFO info;
      info.dwType = 0x1000;
      info.szName = threadName;
      info.dwThreadID = ~0U;
      info.dwFlags = 0;

      RaiseException(0x406D1388,
                     0,
                     sizeof(info) / sizeof(ULONG_PTR),
                     (ULONG_PTR *)&info);
   } __except (EXCEPTION_EXECUTE_HANDLER) {
   }
#elif defined(__MINGW32__)
/* No option known to set thread name for MinGW */
#endif
#elif defined(_GNU_SOURCE) && defined(__GLIBC__)                               \
    && ((__GLIBC__ > 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 12)))
/* pthread_setname_np first appeared in glibc in version 2.12*/
#if defined(__MACH__)
   /* OS X only current thread name can be changed */
   (void)pthread_setname_np(threadName);
#else
   (void)pthread_setname_np(pthread_self(), threadName);
#endif
#elif defined(__linux__)
   /* on linux we can use the old prctl function */
   (void)prctl(PR_SET_NAME, threadName, 0, 0, 0);
#endif
}
#else /* !defined(NO_THREAD_NAME) */
void
mg_set_thread_name(const char *threadName)
{
}
#endif


#if defined(MG_LEGACY_INTERFACE)
const char **
mg_get_valid_option_names(void)
{
   /* This function is deprecated. Use mg_get_valid_options instead. */
   static const char
       *data[2 * sizeof(config_options) / sizeof(config_options[0])] = {0};
   int i;

   for (i = 0; config_options[i].name != NULL; i++) {
      data[i * 2] = config_options[i].name;
      data[i * 2 + 1] = config_options[i].default_value;
   }

   return data;
}
#endif


const struct mg_option *
mg_get_valid_options(void)
{
   return config_options;
}


/* Do not open file (used in is_file_in_memory) */
#define MG_FOPEN_MODE_NONE (0)

/* Open file for read only access */
#define MG_FOPEN_MODE_READ (1)

/* Open file for writing, create and overwrite */
#define MG_FOPEN_MODE_WRITE (2)

/* Open file for writing, create and append */
#define MG_FOPEN_MODE_APPEND (4)


/* If a file is in memory, set all "stat" members and the membuf pointer of
 * output filep and return 1, otherwise return 0 and don't modify anything.
 */
static int
open_file_in_memory(const struct mg_connection *conn,
                    const char *path,
                    struct mg_file *filep,
                    int mode)
{
#if defined(MG_USE_OPEN_FILE)

   size_t size = 0;
   const char *buf = NULL;
   if (!conn) {
      return 0;
   }

   if ((mode != MG_FOPEN_MODE_NONE) && (mode != MG_FOPEN_MODE_READ)) {
      return 0;
   }

   if (conn->phys_ctx->callbacks.open_file) {
      buf = conn->phys_ctx->callbacks.open_file(conn, path, &size);
      if (buf != NULL) {
         if (filep == NULL) {
            /* This is a file in memory, but we cannot store the
             * properties
             * now.
             * Called from "is_file_in_memory" function. */
            return 1;
         }

         /* NOTE: override filep->size only on success. Otherwise, it
          * might
          * break constructs like if (!mg_stat() || !mg_fopen()) ... */
         filep->access.membuf = buf;
         filep->access.fp = NULL;

         /* Size was set by the callback */
         filep->stat.size = size;

         /* Assume the data may change during runtime by setting
          * last_modified = now */
         filep->stat.last_modified = time(NULL);

         filep->stat.is_directory = 0;
         filep->stat.is_gzipped = 0;
      }
   }

   return (buf != NULL);

#else
   (void)conn;
   (void)path;
   (void)filep;
   (void)mode;

   return 0;

#endif
}


static int
is_file_in_memory(const struct mg_connection *conn, const char *path)
{
   return open_file_in_memory(conn, path, NULL, MG_FOPEN_MODE_NONE);
}


static int
is_file_opened(const struct mg_file_access *fileacc)
{
   if (!fileacc) {
      return 0;
   }

#if defined(MG_USE_OPEN_FILE)
   return (fileacc->membuf != NULL) || (fileacc->fp != NULL);
#else
   return (fileacc->fp != NULL);
#endif
}


static int mg_stat(const struct mg_connection *conn,
                   const char *path,
                   struct mg_file_stat *filep);


/* mg_fopen will open a file either in memory or on the disk.
 * The input parameter path is a string in UTF-8 encoding.
 * The input parameter mode is MG_FOPEN_MODE_*
 * On success, either fp or membuf will be set in the output
 * struct file. All status members will also be set.
 * The function returns 1 on success, 0 on error. */
static int
mg_fopen(const struct mg_connection *conn,
         const char *path,
         int mode,
         struct mg_file *filep)
{
   int found;

   if (!filep) {
      return 0;
   }
   filep->access.fp = NULL;
#if defined(MG_USE_OPEN_FILE)
   filep->access.membuf = NULL;
#endif

   if (!is_file_in_memory(conn, path)) {

      /* filep is initialized in mg_stat: all fields with memset to,
       * some fields like size and modification date with values */
      found = mg_stat(conn, path, &(filep->stat));

      if ((mode == MG_FOPEN_MODE_READ) && (!found)) {
         /* file does not exist and will not be created */
         return 0;
      }

#if defined(_WIN32)
      {
         wchar_t wbuf[W_PATH_MAX];
         path_to_unicode(conn, path, wbuf, ARRAY_SIZE(wbuf));
         switch (mode) {
         case MG_FOPEN_MODE_READ:
            filep->access.fp = _wfopen(wbuf, L"rb");
            break;
         case MG_FOPEN_MODE_WRITE:
            filep->access.fp = _wfopen(wbuf, L"wb");
            break;
         case MG_FOPEN_MODE_APPEND:
            filep->access.fp = _wfopen(wbuf, L"ab");
            break;
         }
      }
#else
      /* Linux et al already use unicode. No need to convert. */
      switch (mode) {
      case MG_FOPEN_MODE_READ:
         filep->access.fp = fopen(path, "r");
         break;
      case MG_FOPEN_MODE_WRITE:
         filep->access.fp = fopen(path, "w");
         break;
      case MG_FOPEN_MODE_APPEND:
         filep->access.fp = fopen(path, "a");
         break;
      }

#endif
      if (!found) {
         /* File did not exist before fopen was called.
          * Maybe it has been created now. Get stat info
          * like creation time now. */
         found = mg_stat(conn, path, &(filep->stat));
         (void)found;
      }

      /* file is on disk */
      return (filep->access.fp != NULL);

   } else {
#if defined(MG_USE_OPEN_FILE)
      /* is_file_in_memory returned true */
      if (open_file_in_memory(conn, path, filep, mode)) {
         /* file is in memory */
         return (filep->access.membuf != NULL);
      }
#endif
   }

   /* Open failed */
   return 0;
}


/* return 0 on success, just like fclose */
static int
mg_fclose(struct mg_file_access *fileacc)
{
   int ret = -1;
   if (fileacc != NULL) {
      if (fileacc->fp != NULL) {
         ret = fclose(fileacc->fp);
#if defined(MG_USE_OPEN_FILE)
      } else if (fileacc->membuf != NULL) {
         ret = 0;
#endif
      }
      /* reset all members of fileacc */
      memset(fileacc, 0, sizeof(*fileacc));
   }
   return ret;
}


static void
mg_strlcpy(register char *dst, register const char *src, size_t n)
{
   for (; *src != '\0' && n > 1; n--) {
      *dst++ = *src++;
   }
   *dst = '\0';
}


static int
lowercase(const char *s)
{
   return tolower(*(const unsigned char *)s);
}


int
mg_strncasecmp(const char *s1, const char *s2, size_t len)
{
   int diff = 0;

   if (len > 0) {
      do {
         diff = lowercase(s1++) - lowercase(s2++);
      } while (diff == 0 && s1[-1] != '\0' && --len > 0);
   }

   return diff;
}


int
mg_strcasecmp(const char *s1, const char *s2)
{
   int diff;

   do {
      diff = lowercase(s1++) - lowercase(s2++);
   } while (diff == 0 && s1[-1] != '\0');

   return diff;
}


static char *
mg_strndup_ctx(const char *ptr, size_t len, struct mg_context *ctx)
{
   char *p;
   (void)ctx; /* Avoid Visual Studio warning if USE_SERVER_STATS is not
               * defined */

   if ((p = (char *)mg_malloc_ctx(len + 1, ctx)) != NULL) {
      mg_strlcpy(p, ptr, len + 1);
   }

   return p;
}


static char *
mg_strdup_ctx(const char *str, struct mg_context *ctx)
{
   return mg_strndup_ctx(str, strlen(str), ctx);
}

static char *
mg_strdup(const char *str)
{
   return mg_strndup_ctx(str, strlen(str), NULL);
}


static const char *
mg_strcasestr(const char *big_str, const char *small_str)
{
   size_t i, big_len = strlen(big_str), small_len = strlen(small_str);

   if (big_len >= small_len) {
      for (i = 0; i <= (big_len - small_len); i++) {
         if (mg_strncasecmp(big_str + i, small_str, small_len) == 0) {
            return big_str + i;
         }
      }
   }

   return NULL;
}


/* Return null terminated string of given maximum length.
 * Report errors if length is exceeded. */
static void
mg_vsnprintf(const struct mg_connection *conn,
             int *truncated,
             char *buf,
             size_t buflen,
             const char *fmt,
             va_list ap)
{
   int n, ok;

   if (buflen == 0) {
      if (truncated) {
         *truncated = 1;
      }
      return;
   }

#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wformat-nonliteral"
/* Using fmt as a non-literal is intended here, since it is mostly called
 * indirectly by mg_snprintf */
#endif

   n = (int)vsnprintf_impl(buf, buflen, fmt, ap);
   ok = (n >= 0) && ((size_t)n < buflen);

#if defined(__clang__)
#pragma clang diagnostic pop
#endif

   if (ok) {
      if (truncated) {
         *truncated = 0;
      }
   } else {
      if (truncated) {
         *truncated = 1;
      }
      mg_cry_internal(conn,
                      "truncating vsnprintf buffer: [%.*s]",
                      (int)((buflen > 200) ? 200 : (buflen - 1)),
                      buf);
      n = (int)buflen - 1;
   }
   buf[n] = '\0';
}


static void
mg_snprintf(const struct mg_connection *conn,
            int *truncated,
            char *buf,
            size_t buflen,
            const char *fmt,
            ...)
{
   va_list ap;

   va_start(ap, fmt);
   mg_vsnprintf(conn, truncated, buf, buflen, fmt, ap);
   va_end(ap);
}


static int
get_option_index(const char *name)
{
   int i;

   for (i = 0; config_options[i].name != NULL; i++) {
      if (strcmp(config_options[i].name, name) == 0) {
         return i;
      }
   }
   return -1;
}


const char *
mg_get_option(const struct mg_context *ctx, const char *name)
{
   int i;
   if ((i = get_option_index(name)) == -1) {
      return NULL;
   } else if (!ctx || ctx->dd.config[i] == NULL) {
      return "";
   } else {
      return ctx->dd.config[i];
   }
}

#define mg_get_option DO_NOT_USE_THIS_FUNCTION_INTERNALLY__access_directly

struct mg_context *
mg_get_context(const struct mg_connection *conn)
{
   return (conn == NULL) ? (struct mg_context *)NULL : (conn->phys_ctx);
}


void *
mg_get_user_data(const struct mg_context *ctx)
{
   return (ctx == NULL) ? NULL : ctx->user_data;
}


void
mg_set_user_connection_data(struct mg_connection *conn, void *data)
{
   if (conn != NULL) {
      conn->request_info.conn_data = data;
   }
}


void *
mg_get_user_connection_data(const struct mg_connection *conn)
{
   if (conn != NULL) {
      return conn->request_info.conn_data;
   }
   return NULL;
}


#if defined(MG_LEGACY_INTERFACE)
/* Deprecated: Use mg_get_server_ports instead. */
size_t
mg_get_ports(const struct mg_context *ctx, size_t size, int *ports, int *ssl)
{
   size_t i;
   if (!ctx) {
      return 0;
   }
   for (i = 0; i < size && i < ctx->num_listening_sockets; i++) {
      ssl[i] = ctx->listening_sockets[i].is_ssl;
      ports[i] =
#if defined(USE_IPV6)
          (ctx->listening_sockets[i].lsa.sa.sa_family == AF_INET6)
              ? ntohs(ctx->listening_sockets[i].lsa.sin6.sin6_port)
              :
#endif
              ntohs(ctx->listening_sockets[i].lsa.sin.sin_port);
   }
   return i;
}
#endif


int
mg_get_server_ports(const struct mg_context *ctx,
                    int size,
                    struct mg_server_ports *ports)
{
   int i, cnt = 0;

   if (size <= 0) {
      return -1;
   }
   memset(ports, 0, sizeof(*ports) * (size_t)size);
   if (!ctx) {
      return -1;
   }
   if (!ctx->listening_sockets) {
      return -1;
   }

   for (i = 0; (i < size) && (i < (int)ctx->num_listening_sockets); i++) {

      ports[cnt].port =
#if defined(USE_IPV6)
          (ctx->listening_sockets[i].lsa.sa.sa_family == AF_INET6)
              ? ntohs(ctx->listening_sockets[i].lsa.sin6.sin6_port)
              :
#endif
              ntohs(ctx->listening_sockets[i].lsa.sin.sin_port);
      ports[cnt].is_ssl = ctx->listening_sockets[i].is_ssl;
      ports[cnt].is_redirect = ctx->listening_sockets[i].ssl_redir;

      if (ctx->listening_sockets[i].lsa.sa.sa_family == AF_INET) {
         /* IPv4 */
         ports[cnt].protocol = 1;
         cnt++;
      } else if (ctx->listening_sockets[i].lsa.sa.sa_family == AF_INET6) {
         /* IPv6 */
         ports[cnt].protocol = 3;
         cnt++;
      }
   }

   return cnt;
}


static void
sockaddr_to_string(char *buf, size_t len, const union usa *usa)
{
   buf[0] = '\0';

   if (!usa) {
      return;
   }

   if (usa->sa.sa_family == AF_INET) {
      getnameinfo(&usa->sa,
                  sizeof(usa->sin),
                  buf,
                  (unsigned)len,
                  NULL,
                  0,
                  NI_NUMERICHOST);
   }
#if defined(USE_IPV6)
   else if (usa->sa.sa_family == AF_INET6) {
      getnameinfo(&usa->sa,
                  sizeof(usa->sin6),
                  buf,
                  (unsigned)len,
                  NULL,
                  0,
                  NI_NUMERICHOST);
   }
#endif
}


/* Convert time_t to a string. According to RFC2616, Sec 14.18, this must be
 * included in all responses other than 100, 101, 5xx. */
static void
gmt_time_string(char *buf, size_t buf_len, time_t *t)
{
#if !defined(REENTRANT_TIME)
   struct tm *tm;

   tm = ((t != NULL) ? gmtime(t) : NULL);
   if (tm != NULL) {
#else
   struct tm _tm;
   struct tm *tm = &_tm;

   if (t != NULL) {
      gmtime_r(t, tm);
#endif
      strftime(buf, buf_len, "%a, %d %b %Y %H:%M:%S GMT", tm);
   } else {
      mg_strlcpy(buf, "Thu, 01 Jan 1970 00:00:00 GMT", buf_len);
      buf[buf_len - 1] = '\0';
   }
}


/* difftime for struct timespec. Return value is in seconds. */
static double
mg_difftimespec(const struct timespec *ts_now, const struct timespec *ts_before)
{
   return (double)(ts_now->tv_nsec - ts_before->tv_nsec) * 1.0E-9
          + (double)(ts_now->tv_sec - ts_before->tv_sec);
}


#if defined(MG_EXTERNAL_FUNCTION_mg_cry_internal_impl)
static void mg_cry_internal_impl(const struct mg_connection *conn,
                                 const char *func,
                                 unsigned line,
                                 const char *fmt,
                                 va_list ap);
#include "external_mg_cry_internal_impl.inl"
#else

/* Print error message to the opened error log stream. */
static void
mg_cry_internal_impl(const struct mg_connection *conn,
                     const char *func,
                     unsigned line,
                     const char *fmt,
                     va_list ap)
{
   char buf[MG_BUF_LEN], src_addr[IP_ADDR_STR_LEN];
   struct mg_file fi;
   time_t timestamp;

   /* Unused, in the RELEASE build */
   (void)func;
   (void)line;

#if defined(GCC_DIAGNOSTIC)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-nonliteral"
#endif

   IGNORE_UNUSED_RESULT(vsnprintf_impl(buf, sizeof(buf), fmt, ap));

#if defined(GCC_DIAGNOSTIC)
#pragma GCC diagnostic pop
#endif

   buf[sizeof(buf) - 1] = 0;

   DEBUG_TRACE("mg_cry called from %s:%u: %s", func, line, buf);

   if (!conn) {
      puts(buf);
      return;
   }

   /* Do not lock when getting the callback value, here and below.
    * I suppose this is fine, since function cannot disappear in the
    * same way string option can. */
   if ((conn->phys_ctx->callbacks.log_message == NULL)
       || (conn->phys_ctx->callbacks.log_message(conn, buf) == 0)) {

      if (conn->dom_ctx->config[ERROR_LOG_FILE] != NULL) {
         if (mg_fopen(conn,
                      conn->dom_ctx->config[ERROR_LOG_FILE],
                      MG_FOPEN_MODE_APPEND,
                      &fi)
             == 0) {
            fi.access.fp = NULL;
         }
      } else {
         fi.access.fp = NULL;
      }

      if (fi.access.fp != NULL) {
         flockfile(fi.access.fp);
         timestamp = time(NULL);

         sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);
         fprintf(fi.access.fp,
                 "[%010lu] [error] [client %s] ",
                 (unsigned long)timestamp,
                 src_addr);

         if (conn->request_info.request_method != NULL) {
            fprintf(fi.access.fp,
                    "%s %s: ",
                    conn->request_info.request_method,
                    conn->request_info.request_uri
                        ? conn->request_info.request_uri
                        : "");
         }

         fprintf(fi.access.fp, "%s", buf);
         fputc('\n', fi.access.fp);
         fflush(fi.access.fp);
         funlockfile(fi.access.fp);
         (void)mg_fclose(&fi.access); /* Ignore errors. We can't call
                                       * mg_cry here anyway ;-) */
      }
   }
}

#endif /* Externally provided function */


static void
mg_cry_internal_wrap(const struct mg_connection *conn,
                     const char *func,
                     unsigned line,
                     const char *fmt,
                     ...)
{
   va_list ap;
   va_start(ap, fmt);
   mg_cry_internal_impl(conn, func, line, fmt, ap);
   va_end(ap);
}


void
mg_cry(const struct mg_connection *conn, const char *fmt, ...)
{
   va_list ap;
   va_start(ap, fmt);
   mg_cry_internal_impl(conn, "user", 0, fmt, ap);
   va_end(ap);
}


#define mg_cry DO_NOT_USE_THIS_FUNCTION__USE_mg_cry_internal


/* Return fake connection structure. Used for logging, if connection
 * is not applicable at the moment of logging. */
static struct mg_connection *
fc(struct mg_context *ctx)
{
   static struct mg_connection fake_connection;
   fake_connection.phys_ctx = ctx;
   fake_connection.dom_ctx = &(ctx->dd);
   return &fake_connection;
}


const char *
mg_version(void)
{
   return CIVETWEB_VERSION;
}


const struct mg_request_info *
mg_get_request_info(const struct mg_connection *conn)
{
   if (!conn) {
      return NULL;
   }
#if defined(MG_ALLOW_USING_GET_REQUEST_INFO_FOR_RESPONSE)
   if (conn->connection_type == CONNECTION_TYPE_RESPONSE) {
      char txt[16];
      struct mg_workerTLS *tls =
          (struct mg_workerTLS *)pthread_getspecific(sTlsKey);

      sprintf(txt, "%03i", conn->response_info.status_code);
      if (strlen(txt) == 3) {
         memcpy(tls->txtbuf, txt, 4);
      } else {
         strcpy(tls->txtbuf, "ERR");
      }

      ((struct mg_connection *)conn)->request_info.local_uri =
          ((struct mg_connection *)conn)->request_info.request_uri =
              tls->txtbuf; /* use thread safe buffer */

      ((struct mg_connection *)conn)->request_info.num_headers =
          conn->response_info.num_headers;
      memcpy(((struct mg_connection *)conn)->request_info.http_headers,
             conn->response_info.http_headers,
             sizeof(conn->response_info.http_headers));
   } else
#endif
       if (conn->connection_type != CONNECTION_TYPE_REQUEST) {
      return NULL;
   }
   return &conn->request_info;
}


const struct mg_response_info *
mg_get_response_info(const struct mg_connection *conn)
{
   if (!conn) {
      return NULL;
   }
   if (conn->connection_type != CONNECTION_TYPE_RESPONSE) {
      return NULL;
   }
   return &conn->response_info;
}


static const char *
get_proto_name(const struct mg_connection *conn)
{
#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunreachable-code"
/* Depending on USE_WEBSOCKET and NO_SSL, some oft the protocols might be
 * not supported. Clang raises an "unreachable code" warning for parts of ?:
 * unreachable, but splitting into four different #ifdef clauses here is more
 * complicated.
 */
#endif

   const struct mg_request_info *ri = &conn->request_info;

   const char *proto =
       (is_websocket_protocol(conn) ? (ri->is_ssl ? "wss" : "ws")
                                    : (ri->is_ssl ? "https" : "http"));

   return proto;

#if defined(__clang__)
#pragma clang diagnostic pop
#endif
}


int
mg_get_request_link(const struct mg_connection *conn, char *buf, size_t buflen)
{
   if ((buflen < 1) || (buf == 0) || (conn == 0)) {
      return -1;
   } else {

      int truncated = 0;
      const struct mg_request_info *ri = &conn->request_info;

      const char *proto = get_proto_name(conn);

      if (ri->local_uri == NULL) {
         return -1;
      }

      if ((ri->request_uri != NULL)
          && (0 != strcmp(ri->local_uri, ri->request_uri))) {
         /* The request uri is different from the local uri.
          * This is usually if an absolute URI, including server
          * name has been provided. */
         mg_snprintf(conn,
                     &truncated,
                     buf,
                     buflen,
                     "%s://%s",
                     proto,
                     ri->request_uri);
         if (truncated) {
            return -1;
         }
         return 0;

      } else {

         /* The common case is a relative URI, so we have to
          * construct an absolute URI from server name and port */

#if defined(USE_IPV6)
         int is_ipv6 = (conn->client.lsa.sa.sa_family == AF_INET6);
         int port = is_ipv6 ? htons(conn->client.lsa.sin6.sin6_port)
                            : htons(conn->client.lsa.sin.sin_port);
#else
         int port = htons(conn->client.lsa.sin.sin_port);
#endif
         int def_port = ri->is_ssl ? 443 : 80;
         int auth_domain_check_enabled =
             conn->dom_ctx->config[ENABLE_AUTH_DOMAIN_CHECK]
             && (!mg_strcasecmp(
                    conn->dom_ctx->config[ENABLE_AUTH_DOMAIN_CHECK], "yes"));
         const char *server_domain =
             conn->dom_ctx->config[AUTHENTICATION_DOMAIN];

         char portstr[16];
         char server_ip[48];

         if (port != def_port) {
            sprintf(portstr, ":%u", (unsigned)port);
         } else {
            portstr[0] = 0;
         }

         if (!auth_domain_check_enabled || !server_domain) {

            sockaddr_to_string(server_ip,
                               sizeof(server_ip),
                               &conn->client.lsa);

            server_domain = server_ip;
         }

         mg_snprintf(conn,
                     &truncated,
                     buf,
                     buflen,
                     "%s://%s%s%s",
                     proto,
                     server_domain,
                     portstr,
                     ri->local_uri);
         if (truncated) {
            return -1;
         }
         return 0;
      }
   }
}

/* Skip the characters until one of the delimiters characters found.
 * 0-terminate resulting word. Skip the delimiter and following whitespaces.
 * Advance pointer to buffer to the next word. Return found 0-terminated
 * word.
 * Delimiters can be quoted with quotechar. */
static char *
skip_quoted(char **buf,
            const char *delimiters,
            const char *whitespace,
            char quotechar)
{
   char *p, *begin_word, *end_word, *end_whitespace;

   begin_word = *buf;
   end_word = begin_word + strcspn(begin_word, delimiters);

   /* Check for quotechar */
   if (end_word > begin_word) {
      p = end_word - 1;
      while (*p == quotechar) {
         /* While the delimiter is quoted, look for the next delimiter.
          */
         /* This happens, e.g., in calls from parse_auth_header,
          * if the user name contains a " character. */

         /* If there is anything beyond end_word, copy it. */
         if (*end_word != '\0') {
            size_t end_off = strcspn(end_word + 1, delimiters);
            memmove(p, end_word, end_off + 1);
            p += end_off; /* p must correspond to end_word - 1 */
            end_word += end_off + 1;
         } else {
            *p = '\0';
            break;
         }
      }
      for (p++; p < end_word; p++) {
         *p = '\0';
      }
   }

   if (*end_word == '\0') {
      *buf = end_word;
   } else {

#if defined(GCC_DIAGNOSTIC)
/* Disable spurious conversion warning for GCC */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsign-conversion"
#endif /* defined(GCC_DIAGNOSTIC) */

      end_whitespace = end_word + strspn(&end_word[1], whitespace) + 1;

#if defined(GCC_DIAGNOSTIC)
#pragma GCC diagnostic pop
#endif /* defined(GCC_DIAGNOSTIC) */

      for (p = end_word; p < end_whitespace; p++) {
         *p = '\0';
      }

      *buf = end_whitespace;
   }

   return begin_word;
}


/* Return HTTP header value, or NULL if not found. */
static const char *
get_header(const struct mg_header *hdr, int num_hdr, const char *name)
{
   int i;
   for (i = 0; i < num_hdr; i++) {
      if (!mg_strcasecmp(name, hdr[i].name)) {
         return hdr[i].value;
      }
   }

   return NULL;
}


#if defined(USE_WEBSOCKET)
/* Retrieve requested HTTP header multiple values, and return the number of
 * found occurrences */
static int
get_req_headers(const struct mg_request_info *ri,
                const char *name,
                const char **output,
                int output_max_size)
{
   int i;
   int cnt = 0;
   if (ri) {
      for (i = 0; i < ri->num_headers && cnt < output_max_size; i++) {
         if (!mg_strcasecmp(name, ri->http_headers[i].name)) {
            output[cnt++] = ri->http_headers[i].value;
         }
      }
   }
   return cnt;
}
#endif


const char *
mg_get_header(const struct mg_connection *conn, const char *name)
{
   if (!conn) {
      return NULL;
   }

   if (conn->connection_type == CONNECTION_TYPE_REQUEST) {
      return get_header(conn->request_info.http_headers,
                        conn->request_info.num_headers,
                        name);
   }
   if (conn->connection_type == CONNECTION_TYPE_RESPONSE) {
      return get_header(conn->response_info.http_headers,
                        conn->response_info.num_headers,
                        name);
   }
   return NULL;
}


static const char *
get_http_version(const struct mg_connection *conn)
{
   if (!conn) {
      return NULL;
   }

   if (conn->connection_type == CONNECTION_TYPE_REQUEST) {
      return conn->request_info.http_version;
   }
   if (conn->connection_type == CONNECTION_TYPE_RESPONSE) {
      return conn->response_info.http_version;
   }
   return NULL;
}


/* A helper function for traversing a comma separated list of values.
 * It returns a list pointer shifted to the next value, or NULL if the end
 * of the list found.
 * Value is stored in val vector. If value has form "x=y", then eq_val
 * vector is initialized to point to the "y" part, and val vector length
 * is adjusted to point only to "x". */
static const char *
next_option(const char *list, struct vec *val, struct vec *eq_val)
{
   int end;

reparse:
   if (val == NULL || list == NULL || *list == '\0') {
      /* End of the list */
      return NULL;
   }

   /* Skip over leading LWS */
   while (*list == ' ' || *list == '\t')
      list++;

   val->ptr = list;
   if ((list = strchr(val->ptr, ',')) != NULL) {
      /* Comma found. Store length and shift the list ptr */
      val->len = ((size_t)(list - val->ptr));
      list++;
   } else {
      /* This value is the last one */
      list = val->ptr + strlen(val->ptr);
      val->len = ((size_t)(list - val->ptr));
   }

   /* Adjust length for trailing LWS */
   end = (int)val->len - 1;
   while (end >= 0 && ((val->ptr[end] == ' ') || (val->ptr[end] == '\t')))
      end--;
   val->len = (size_t)(end + 1);

   if (val->len == 0) {
      /* Ignore any empty entries. */
      goto reparse;
   }

   if (eq_val != NULL) {
      /* Value has form "x=y", adjust pointers and lengths
       * so that val points to "x", and eq_val points to "y". */
      eq_val->len = 0;
      eq_val->ptr = (const char *)memchr(val->ptr, '=', val->len);
      if (eq_val->ptr != NULL) {
         eq_val->ptr++; /* Skip over '=' character */
         eq_val->len = ((size_t)(val->ptr - eq_val->ptr)) + val->len;
         val->len = ((size_t)(eq_val->ptr - val->ptr)) - 1;
      }
   }

   return list;
}


/* A helper function for checking if a comma separated list of values
 * contains
 * the given option (case insensitvely).
 * 'header' can be NULL, in which case false is returned. */
static int
header_has_option(const char *header, const char *option)
{
   struct vec opt_vec;
   struct vec eq_vec;

   DEBUG_ASSERT(option != NULL);
   DEBUG_ASSERT(option[0] != '\0');

   while ((header = next_option(header, &opt_vec, &eq_vec)) != NULL) {
      if (mg_strncasecmp(option, opt_vec.ptr, opt_vec.len) == 0)
         return 1;
   }

   return 0;
}


/* Perform case-insensitive match of string against pattern */
static ptrdiff_t
match_prefix(const char *pattern, size_t pattern_len, const char *str)
{
   const char *or_str;
   ptrdiff_t i, j, len, res;

   if ((or_str = (const char *)memchr(pattern, '|', pattern_len)) != NULL) {
      res = match_prefix(pattern, (size_t)(or_str - pattern), str);
      return (res > 0) ? res
                       : match_prefix(or_str + 1,
                                      (size_t)((pattern + pattern_len)
                                               - (or_str + 1)),
                                      str);
   }

   for (i = 0, j = 0; (i < (ptrdiff_t)pattern_len); i++, j++) {
      if ((pattern[i] == '?') && (str[j] != '\0')) {
         continue;
      } else if (pattern[i] == '$') {
         return (str[j] == '\0') ? j : -1;
      } else if (pattern[i] == '*') {
         i++;
         if (pattern[i] == '*') {
            i++;
            len = strlen(str + j);
         } else {
            len = strcspn(str + j, "/");
         }
         if (i == (ptrdiff_t)pattern_len) {
            return j + len;
         }
         do {
            res = match_prefix(pattern + i, pattern_len - i, str + j + len);
         } while (res == -1 && len-- > 0);
         return (res == -1) ? -1 : j + res + len;
      } else if (lowercase(&pattern[i]) != lowercase(&str[j])) {
         return -1;
      }
   }
   return (ptrdiff_t)j;
}


/* HTTP 1.1 assumes keep alive if "Connection:" header is not set
 * This function must tolerate situations when connection info is not
 * set up, for example if request parsing failed. */
static int
should_keep_alive(const struct mg_connection *conn)
{
   const char *http_version;
   const char *header;

   /* First satisfy needs of the server */
   if ((conn == NULL) || conn->must_close) {
      /* Close, if civetweb framework needs to close */
      return 0;
   }

   if (mg_strcasecmp(conn->dom_ctx->config[ENABLE_KEEP_ALIVE], "yes") != 0) {
      /* Close, if keep alive is not enabled */
      return 0;
   }

   /* Check explicit wish of the client */
   header = mg_get_header(conn, "Connection");
   if (header) {
      /* If there is a connection header from the client, obey */
      if (header_has_option(header, "keep-alive")) {
         return 1;
      }
      return 0;
   }

   /* Use default of the standard */
   http_version = get_http_version(conn);
   if (http_version && (0 == strcmp(http_version, "1.1"))) {
      /* HTTP 1.1 default is keep alive */
      return 1;
   }

   /* HTTP 1.0 (and earlier) default is to close the connection */
   return 0;
}


static int
should_decode_url(const struct mg_connection *conn)
{
   if (!conn || !conn->dom_ctx) {
      return 0;
   }

   return (mg_strcasecmp(conn->dom_ctx->config[DECODE_URL], "yes") == 0);
}


static const char *
suggest_connection_header(const struct mg_connection *conn)
{
   return should_keep_alive(conn) ? "keep-alive" : "close";
}


static int
send_no_cache_header(struct mg_connection *conn)
{
   /* Send all current and obsolete cache opt-out directives. */
   return mg_printf(conn,
                    "Cache-Control: no-cache, no-store, "
                    "must-revalidate, private, max-age=0\r\n"
                    "Pragma: no-cache\r\n"
                    "Expires: 0\r\n");
}


static int
send_static_cache_header(struct mg_connection *conn)
{
#if !defined(NO_CACHING)
   /* Read the server config to check how long a file may be cached.
    * The configuration is in seconds. */
   int max_age = atoi(conn->dom_ctx->config[STATIC_FILE_MAX_AGE]);
   if (max_age <= 0) {
      /* 0 means "do not cache". All values <0 are reserved
       * and may be used differently in the future. */
      /* If a file should not be cached, do not only send
       * max-age=0, but also pragmas and Expires headers. */
      return send_no_cache_header(conn);
   }

   /* Use "Cache-Control: max-age" instead of "Expires" header.
    * Reason: see https://www.mnot.net/blog/2007/05/15/expires_max-age */
   /* See also https://www.mnot.net/cache_docs/ */
   /* According to RFC 2616, Section 14.21, caching times should not exceed
    * one year. A year with 365 days corresponds to 31536000 seconds, a
    * leap
    * year to 31622400 seconds. For the moment, we just send whatever has
    * been configured, still the behavior for >1 year should be considered
    * as undefined. */
   return mg_printf(conn, "Cache-Control: max-age=%u\r\n", (unsigned)max_age);
#else  /* NO_CACHING */
   return send_no_cache_header(conn);
#endif /* !NO_CACHING */
}


static int
send_additional_header(struct mg_connection *conn)
{
   int i = 0;
   const char *header = conn->dom_ctx->config[ADDITIONAL_HEADER];

#if !defined(NO_SSL)
   if (conn->dom_ctx->config[STRICT_HTTPS_MAX_AGE]) {
      int max_age = atoi(conn->dom_ctx->config[STRICT_HTTPS_MAX_AGE]);
      if (max_age >= 0) {
         i += mg_printf(conn,
                        "Strict-Transport-Security: max-age=%u\r\n",
                        (unsigned)max_age);
      }
   }
#endif

   if (header && header[0]) {
      i += mg_printf(conn, "%s\r\n", header);
   }

   return i;
}


static void handle_file_based_request(struct mg_connection *conn,
                                      const char *path,
                                      struct mg_file *filep);


const char *
mg_get_response_code_text(const struct mg_connection *conn, int response_code)
{
   /* See IANA HTTP status code assignment:
    * http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
    */

   switch (response_code) {
   /* RFC2616 Section 10.1 - Informational 1xx */
   case 100:
      return "Continue"; /* RFC2616 Section 10.1.1 */
   case 101:
      return "Switching Protocols"; /* RFC2616 Section 10.1.2 */
   case 102:
      return "Processing"; /* RFC2518 Section 10.1 */

   /* RFC2616 Section 10.2 - Successful 2xx */
   case 200:
      return "OK"; /* RFC2616 Section 10.2.1 */
   case 201:
      return "Created"; /* RFC2616 Section 10.2.2 */
   case 202:
      return "Accepted"; /* RFC2616 Section 10.2.3 */
   case 203:
      return "Non-Authoritative Information"; /* RFC2616 Section 10.2.4 */
   case 204:
      return "No Content"; /* RFC2616 Section 10.2.5 */
   case 205:
      return "Reset Content"; /* RFC2616 Section 10.2.6 */
   case 206:
      return "Partial Content"; /* RFC2616 Section 10.2.7 */
   case 207:
      return "Multi-Status"; /* RFC2518 Section 10.2, RFC4918 Section 11.1
                              */
   case 208:
      return "Already Reported"; /* RFC5842 Section 7.1 */

   case 226:
      return "IM used"; /* RFC3229 Section 10.4.1 */

   /* RFC2616 Section 10.3 - Redirection 3xx */
   case 300:
      return "Multiple Choices"; /* RFC2616 Section 10.3.1 */
   case 301:
      return "Moved Permanently"; /* RFC2616 Section 10.3.2 */
   case 302:
      return "Found"; /* RFC2616 Section 10.3.3 */
   case 303:
      return "See Other"; /* RFC2616 Section 10.3.4 */
   case 304:
      return "Not Modified"; /* RFC2616 Section 10.3.5 */
   case 305:
      return "Use Proxy"; /* RFC2616 Section 10.3.6 */
   case 307:
      return "Temporary Redirect"; /* RFC2616 Section 10.3.8 */
   case 308:
      return "Permanent Redirect"; /* RFC7238 Section 3 */

   /* RFC2616 Section 10.4 - Client Error 4xx */
   case 400:
      return "Bad Request"; /* RFC2616 Section 10.4.1 */
   case 401:
      return "Unauthorized"; /* RFC2616 Section 10.4.2 */
   case 402:
      return "Payment Required"; /* RFC2616 Section 10.4.3 */
   case 403:
      return "Forbidden"; /* RFC2616 Section 10.4.4 */
   case 404:
      return "Not Found"; /* RFC2616 Section 10.4.5 */
   case 405:
      return "Method Not Allowed"; /* RFC2616 Section 10.4.6 */
   case 406:
      return "Not Acceptable"; /* RFC2616 Section 10.4.7 */
   case 407:
      return "Proxy Authentication Required"; /* RFC2616 Section 10.4.8 */
   case 408:
      return "Request Time-out"; /* RFC2616 Section 10.4.9 */
   case 409:
      return "Conflict"; /* RFC2616 Section 10.4.10 */
   case 410:
      return "Gone"; /* RFC2616 Section 10.4.11 */
   case 411:
      return "Length Required"; /* RFC2616 Section 10.4.12 */
   case 412:
      return "Precondition Failed"; /* RFC2616 Section 10.4.13 */
   case 413:
      return "Request Entity Too Large"; /* RFC2616 Section 10.4.14 */
   case 414:
      return "Request-URI Too Large"; /* RFC2616 Section 10.4.15 */
   case 415:
      return "Unsupported Media Type"; /* RFC2616 Section 10.4.16 */
   case 416:
      return "Requested range not satisfiable"; /* RFC2616 Section 10.4.17
                                                 */
   case 417:
      return "Expectation Failed"; /* RFC2616 Section 10.4.18 */

   case 421:
      return "Misdirected Request"; /* RFC7540 Section 9.1.2 */
   case 422:
      return "Unproccessable entity"; /* RFC2518 Section 10.3, RFC4918
                                       * Section 11.2 */
   case 423:
      return "Locked"; /* RFC2518 Section 10.4, RFC4918 Section 11.3 */
   case 424:
      return "Failed Dependency"; /* RFC2518 Section 10.5, RFC4918
                                   * Section 11.4 */

   case 426:
      return "Upgrade Required"; /* RFC 2817 Section 4 */

   case 428:
      return "Precondition Required"; /* RFC 6585, Section 3 */
   case 429:
      return "Too Many Requests"; /* RFC 6585, Section 4 */

   case 431:
      return "Request Header Fields Too Large"; /* RFC 6585, Section 5 */

   case 451:
      return "Unavailable For Legal Reasons"; /* draft-tbray-http-legally-restricted-status-05,
                                               * Section 3 */

   /* RFC2616 Section 10.5 - Server Error 5xx */
   case 500:
      return "Internal Server Error"; /* RFC2616 Section 10.5.1 */
   case 501:
      return "Not Implemented"; /* RFC2616 Section 10.5.2 */
   case 502:
      return "Bad Gateway"; /* RFC2616 Section 10.5.3 */
   case 503:
      return "Service Unavailable"; /* RFC2616 Section 10.5.4 */
   case 504:
      return "Gateway Time-out"; /* RFC2616 Section 10.5.5 */
   case 505:
      return "HTTP Version not supported"; /* RFC2616 Section 10.5.6 */
   case 506:
      return "Variant Also Negotiates"; /* RFC 2295, Section 8.1 */
   case 507:
      return "Insufficient Storage"; /* RFC2518 Section 10.6, RFC4918
                                      * Section 11.5 */
   case 508:
      return "Loop Detected"; /* RFC5842 Section 7.1 */

   case 510:
      return "Not Extended"; /* RFC 2774, Section 7 */
   case 511:
      return "Network Authentication Required"; /* RFC 6585, Section 6 */

   /* Other status codes, not shown in the IANA HTTP status code
    * assignment.
    * E.g., "de facto" standards due to common use, ... */
   case 418:
      return "I am a teapot"; /* RFC2324 Section 2.3.2 */
   case 419:
      return "Authentication Timeout"; /* common use */
   case 420:
      return "Enhance Your Calm"; /* common use */
   case 440:
      return "Login Timeout"; /* common use */
   case 509:
      return "Bandwidth Limit Exceeded"; /* common use */

   default:
      /* This error code is unknown. This should not happen. */
      if (conn) {
         mg_cry_internal(conn,
                         "Unknown HTTP response code: %u",
                         response_code);
      }

      /* Return at least a category according to RFC 2616 Section 10. */
      if (response_code >= 100 && response_code < 200) {
         /* Unknown informational status code */
         return "Information";
      }
      if (response_code >= 200 && response_code < 300) {
         /* Unknown success code */
         return "Success";
      }
      if (response_code >= 300 && response_code < 400) {
         /* Unknown redirection code */
         return "Redirection";
      }
      if (response_code >= 400 && response_code < 500) {
         /* Unknown request error code */
         return "Client Error";
      }
      if (response_code >= 500 && response_code < 600) {
         /* Unknown server error code */
         return "Server Error";
      }

      /* Response code not even within reasonable range */
      return "";
   }
}


static int
mg_send_http_error_impl(struct mg_connection *conn,
                        int status,
                        const char *fmt,
                        va_list args)
{
   char errmsg_buf[MG_BUF_LEN];
   char path_buf[PATH_MAX];
   va_list ap;
   int len, i, page_handler_found, scope, truncated, has_body;
   char date[64];
   time_t curtime = time(NULL);
   const char *error_handler = NULL;
   struct mg_file error_page_file = STRUCT_FILE_INITIALIZER;
   const char *error_page_file_ext, *tstr;
   int handled_by_callback = 0;

   const char *status_text = mg_get_response_code_text(conn, status);

   if ((conn == NULL) || (fmt == NULL)) {
      return -2;
   }

   /* Set status (for log) */
   conn->status_code = status;

   /* Errors 1xx, 204 and 304 MUST NOT send a body */
   has_body = ((status > 199) && (status != 204) && (status != 304));

   /* Prepare message in buf, if required */
   if (has_body
       || (!conn->in_error_handler
           && (conn->phys_ctx->callbacks.http_error != NULL))) {
      /* Store error message in errmsg_buf */
      va_copy(ap, args);
      mg_vsnprintf(conn, NULL, errmsg_buf, sizeof(errmsg_buf), fmt, ap);
      va_end(ap);
      /* In a debug build, print all html errors */
      DEBUG_TRACE("Error %i - [%s]", status, errmsg_buf);
   }

   /* If there is a http_error callback, call it.
    * But don't do it recursively, if callback calls mg_send_http_error again.
    */
   if (!conn->in_error_handler
       && (conn->phys_ctx->callbacks.http_error != NULL)) {
      /* Mark in_error_handler to avoid recursion and call user callback. */
      conn->in_error_handler = 1;
      handled_by_callback =
          (conn->phys_ctx->callbacks.http_error(conn, status, errmsg_buf)
           == 0);
      conn->in_error_handler = 0;
   }

   if (!handled_by_callback) {
      /* Check for recursion */
      if (conn->in_error_handler) {
         DEBUG_TRACE(
             "Recursion when handling error %u - fall back to default",
             status);
      } else {
         /* Send user defined error pages, if defined */
         error_handler = conn->dom_ctx->config[ERROR_PAGES];
         error_page_file_ext = conn->dom_ctx->config[INDEX_FILES];
         page_handler_found = 0;

         if (error_handler != NULL) {
            for (scope = 1; (scope <= 3) && !page_handler_found; scope++) {
               switch (scope) {
               case 1: /* Handler for specific error, e.g. 404 error */
                  mg_snprintf(conn,
                              &truncated,
                              path_buf,
                              sizeof(path_buf) - 32,
                              "%serror%03u.",
                              error_handler,
                              status);
                  break;
               case 2: /* Handler for error group, e.g., 5xx error
                        * handler
                        * for all server errors (500-599) */
                  mg_snprintf(conn,
                              &truncated,
                              path_buf,
                              sizeof(path_buf) - 32,
                              "%serror%01uxx.",
                              error_handler,
                              status / 100);
                  break;
               default: /* Handler for all errors */
                  mg_snprintf(conn,
                              &truncated,
                              path_buf,
                              sizeof(path_buf) - 32,
                              "%serror.",
                              error_handler);
                  break;
               }

               /* String truncation in buf may only occur if
                * error_handler is too long. This string is
                * from the config, not from a client. */
               (void)truncated;

               len = (int)strlen(path_buf);

               tstr = strchr(error_page_file_ext, '.');

               while (tstr) {
                  for (i = 1;
                       (i < 32) && (tstr[i] != 0) && (tstr[i] != ',');
                       i++) {
                     /* buffer overrun is not possible here, since
                      * (i < 32) && (len < sizeof(path_buf) - 32)
                      * ==> (i + len) < sizeof(path_buf) */
                     path_buf[len + i - 1] = tstr[i];
                  }
                  /* buffer overrun is not possible here, since
                   * (i <= 32) && (len < sizeof(path_buf) - 32)
                   * ==> (i + len) <= sizeof(path_buf) */
                  path_buf[len + i - 1] = 0;

                  if (mg_stat(conn, path_buf, &error_page_file.stat)) {
                     DEBUG_TRACE("Check error page %s - found",
                                 path_buf);
                     page_handler_found = 1;
                     break;
                  }
                  DEBUG_TRACE("Check error page %s - not found",
                              path_buf);

                  tstr = strchr(tstr + i, '.');
               }
            }
         }

         if (page_handler_found) {
            conn->in_error_handler = 1;
            handle_file_based_request(conn, path_buf, &error_page_file);
            conn->in_error_handler = 0;
            return 0;
         }
      }

      /* No custom error page. Send default error page. */
      gmt_time_string(date, sizeof(date), &curtime);

      conn->must_close = 1;
      mg_printf(conn, "HTTP/1.1 %d %s\r\n", status, status_text);
      send_no_cache_header(conn);
      send_additional_header(conn);
      if (has_body) {
         mg_printf(conn,
                   "%s",
                   "Content-Type: text/plain; charset=utf-8\r\n");
      }
      mg_printf(conn,
                "Date: %s\r\n"
                "Connection: close\r\n\r\n",
                date);

      /* HTTP responses 1xx, 204 and 304 MUST NOT send a body */
      if (has_body) {
         /* For other errors, send a generic error message. */
         mg_printf(conn, "Error %d: %s\n", status, status_text);
         mg_write(conn, errmsg_buf, strlen(errmsg_buf));

      } else {
         /* No body allowed. Close the connection. */
         DEBUG_TRACE("Error %i", status);
      }
   }
   return 0;
}


int
mg_send_http_error(struct mg_connection *conn, int status, const char *fmt, ...)
{
   va_list ap;
   int ret;

   va_start(ap, fmt);
   ret = mg_send_http_error_impl(conn, status, fmt, ap);
   va_end(ap);

   return ret;
}


int
mg_send_http_ok(struct mg_connection *conn,
                const char *mime_type,
                long long content_length)
{
   char date[64];
   time_t curtime = time(NULL);

   if ((mime_type == NULL) || (*mime_type == 0)) {
      /* Parameter error */
      return -2;
   }

   gmt_time_string(date, sizeof(date), &curtime);

   mg_printf(conn,
             "HTTP/1.1 200 OK\r\n"
             "Content-Type: %s\r\n"
             "Date: %s\r\n"
             "Connection: %s\r\n",
             mime_type,
             date,
             suggest_connection_header(conn));

   send_no_cache_header(conn);
   send_additional_header(conn);
   if (content_length < 0) {
      mg_printf(conn, "Transfer-Encoding: chunked\r\n\r\n");
   } else {
      mg_printf(conn,
                "Content-Length: %" UINT64_FMT "\r\n\r\n",
                (uint64_t)content_length);
   }

   return 0;
}


int
mg_send_http_redirect(struct mg_connection *conn,
                      const char *target_url,
                      int redirect_code)
{
   /* Send a 30x redirect response.
    *
    * Redirect types (status codes):
    *
    * Status | Perm/Temp | Method              | Version
    *   301  | permanent | POST->GET undefined | HTTP/1.0
    *   302  | temporary | POST->GET undefined | HTTP/1.0
    *   303  | temporary | always use GET      | HTTP/1.1
    *   307  | temporary | always keep method  | HTTP/1.1
    *   308  | permanent | always keep method  | HTTP/1.1
    */
   const char *redirect_text;
   int ret;
   size_t content_len = 0;
   char reply[MG_BUF_LEN];

   /* In case redirect_code=0, use 307. */
   if (redirect_code == 0) {
      redirect_code = 307;
   }

   /* In case redirect_code is none of the above, return error. */
   if ((redirect_code != 301) && (redirect_code != 302)
       && (redirect_code != 303) && (redirect_code != 307)
       && (redirect_code != 308)) {
      /* Parameter error */
      return -2;
   }

   /* Get proper text for response code */
   redirect_text = mg_get_response_code_text(conn, redirect_code);

   /* If target_url is not defined, redirect to "/". */
   if ((target_url == NULL) || (*target_url == 0)) {
      target_url = "/";
   }

#if defined(MG_SEND_REDIRECT_BODY)
   /* TODO: condition name? */

   /* Prepare a response body with a hyperlink.
    *
    * According to RFC2616 (and RFC1945 before):
    * Unless the request method was HEAD, the entity of the
    * response SHOULD contain a short hypertext note with a hyperlink to
    * the new URI(s).
    *
    * However, this response body is not useful in M2M communication.
    * Probably the original reason in the RFC was, clients not supporting
    * a 30x HTTP redirect could still show the HTML page and let the user
    * press the link. Since current browsers support 30x HTTP, the additional
    * HTML body does not seem to make sense anymore.
    *
    * The new RFC7231 (Section 6.4) does no longer recommend it ("SHOULD"),
    * but it only notes:
    * The server's response payload usually contains a short
    * hypertext note with a hyperlink to the new URI(s).
    *
    * Deactivated by default. If you need the 30x body, set the define.
    */
   mg_snprintf(
       conn,
       NULL /* ignore truncation */,
       reply,
       sizeof(reply),
       "<html><head>%s</head><body><a href=\"%s\">%s</a></body></html>",
       redirect_text,
       target_url,
       target_url);
   content_len = strlen(reply);
#else
   reply[0] = 0;
#endif

   /* Do not send any additional header. For all other options,
    * including caching, there are suitable defaults. */
   ret = mg_printf(conn,
                   "HTTP/1.1 %i %s\r\n"
                   "Location: %s\r\n"
                   "Content-Length: %u\r\n"
                   "Connection: %s\r\n\r\n",
                   redirect_code,
                   redirect_text,
                   target_url,
                   (unsigned int)content_len,
                   suggest_connection_header(conn));

   /* Send response body */
   if (ret > 0) {
      /* ... unless it is a HEAD request */
      if (0 != strcmp(conn->request_info.request_method, "HEAD")) {
         ret = mg_write(conn, reply, content_len);
      }
   }

   return (ret > 0) ? ret : -1;
}


#if defined(_WIN32)
/* Create substitutes for POSIX functions in Win32. */

#if defined(GCC_DIAGNOSTIC)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif


FUNCTION_MAY_BE_UNUSED
static int
pthread_mutex_init(pthread_mutex_t *mutex, void *unused)
{
   (void)unused;
   *mutex = CreateMutex(NULL, FALSE, NULL);
   return (*mutex == NULL) ? -1 : 0;
}

FUNCTION_MAY_BE_UNUSED
static int
pthread_mutex_destroy(pthread_mutex_t *mutex)
{
   return (CloseHandle(*mutex) == 0) ? -1 : 0;
}


FUNCTION_MAY_BE_UNUSED
static int
pthread_mutex_lock(pthread_mutex_t *mutex)
{
   return (WaitForSingleObject(*mutex, (DWORD)INFINITE) == WAIT_OBJECT_0) ? 0
                                                                          : -1;
}


#if defined(ENABLE_UNUSED_PTHREAD_FUNCTIONS)
FUNCTION_MAY_BE_UNUSED
static int
pthread_mutex_trylock(pthread_mutex_t *mutex)
{
   switch (WaitForSingleObject(*mutex, 0)) {
   case WAIT_OBJECT_0:
      return 0;
   case WAIT_TIMEOUT:
      return -2; /* EBUSY */
   }
   return -1;
}
#endif


FUNCTION_MAY_BE_UNUSED
static int
pthread_mutex_unlock(pthread_mutex_t *mutex)
{
   return (ReleaseMutex(*mutex) == 0) ? -1 : 0;
}


FUNCTION_MAY_BE_UNUSED
static int
pthread_cond_init(pthread_cond_t *cv, const void *unused)
{
   (void)unused;
   InitializeCriticalSection(&cv->threadIdSec);
   cv->waiting_thread = NULL;
   return 0;
}


FUNCTION_MAY_BE_UNUSED
static int
pthread_cond_timedwait(pthread_cond_t *cv,
                       pthread_mutex_t *mutex,
                       FUNCTION_MAY_BE_UNUSED const struct timespec *abstime)
{
   struct mg_workerTLS **ptls,
       *tls = (struct mg_workerTLS *)pthread_getspecific(sTlsKey);
   int ok;
   int64_t nsnow, nswaitabs, nswaitrel;
   DWORD mswaitrel;

   EnterCriticalSection(&cv->threadIdSec);
   /* Add this thread to cv's waiting list */
   ptls = &cv->waiting_thread;
   for (; *ptls != NULL; ptls = &(*ptls)->next_waiting_thread)
      ;
   tls->next_waiting_thread = NULL;
   *ptls = tls;
   LeaveCriticalSection(&cv->threadIdSec);

   if (abstime) {
      nsnow = mg_get_current_time_ns();
      nswaitabs =
          (((int64_t)abstime->tv_sec) * 1000000000) + abstime->tv_nsec;
      nswaitrel = nswaitabs - nsnow;
      if (nswaitrel < 0) {
         nswaitrel = 0;
      }
      mswaitrel = (DWORD)(nswaitrel / 1000000);
   } else {
      mswaitrel = (DWORD)INFINITE;
   }

   pthread_mutex_unlock(mutex);
   ok = (WAIT_OBJECT_0
         == WaitForSingleObject(tls->pthread_cond_helper_mutex, mswaitrel));
   if (!ok) {
      ok = 1;
      EnterCriticalSection(&cv->threadIdSec);
      ptls = &cv->waiting_thread;
      for (; *ptls != NULL; ptls = &(*ptls)->next_waiting_thread) {
         if (*ptls == tls) {
            *ptls = tls->next_waiting_thread;
            ok = 0;
            break;
         }
      }
      LeaveCriticalSection(&cv->threadIdSec);
      if (ok) {
         WaitForSingleObject(tls->pthread_cond_helper_mutex,
                             (DWORD)INFINITE);
      }
   }
   /* This thread has been removed from cv's waiting list */
   pthread_mutex_lock(mutex);

   return ok ? 0 : -1;
}


FUNCTION_MAY_BE_UNUSED
static int
pthread_cond_wait(pthread_cond_t *cv, pthread_mutex_t *mutex)
{
   return pthread_cond_timedwait(cv, mutex, NULL);
}


FUNCTION_MAY_BE_UNUSED
static int
pthread_cond_signal(pthread_cond_t *cv)
{
   HANDLE wkup = NULL;
   BOOL ok = FALSE;

   EnterCriticalSection(&cv->threadIdSec);
   if (cv->waiting_thread) {
      wkup = cv->waiting_thread->pthread_cond_helper_mutex;
      cv->waiting_thread = cv->waiting_thread->next_waiting_thread;

      ok = SetEvent(wkup);
      DEBUG_ASSERT(ok);
   }
   LeaveCriticalSection(&cv->threadIdSec);

   return ok ? 0 : 1;
}


FUNCTION_MAY_BE_UNUSED
static int
pthread_cond_broadcast(pthread_cond_t *cv)
{
   EnterCriticalSection(&cv->threadIdSec);
   while (cv->waiting_thread) {
      pthread_cond_signal(cv);
   }
   LeaveCriticalSection(&cv->threadIdSec);

   return 0;
}


FUNCTION_MAY_BE_UNUSED
static int
pthread_cond_destroy(pthread_cond_t *cv)
{
   EnterCriticalSection(&cv->threadIdSec);
   DEBUG_ASSERT(cv->waiting_thread == NULL);
   LeaveCriticalSection(&cv->threadIdSec);
   DeleteCriticalSection(&cv->threadIdSec);

   return 0;
}


#if defined(ALTERNATIVE_QUEUE)
FUNCTION_MAY_BE_UNUSED
static void *
event_create(void)
{
   return (void *)CreateEvent(NULL, FALSE, FALSE, NULL);
}


FUNCTION_MAY_BE_UNUSED
static int
event_wait(void *eventhdl)
{
   int res = WaitForSingleObject((HANDLE)eventhdl, (DWORD)INFINITE);
   return (res == WAIT_OBJECT_0);
}


FUNCTION_MAY_BE_UNUSED
static int
event_signal(void *eventhdl)
{
   return (int)SetEvent((HANDLE)eventhdl);
}


FUNCTION_MAY_BE_UNUSED
static void
event_destroy(void *eventhdl)
{
   CloseHandle((HANDLE)eventhdl);
}
#endif


#if defined(GCC_DIAGNOSTIC)
/* Enable unused function warning again */
#pragma GCC diagnostic pop
#endif


/* For Windows, change all slashes to backslashes in path names. */
static void
change_slashes_to_backslashes(char *path)
{
   int i;

   for (i = 0; path[i] != '\0'; i++) {
      if (path[i] == '/') {
         path[i] = '\\';
      }

      /* remove double backslash (check i > 0 to preserve UNC paths,
       * like \\server\file.txt) */
      if ((path[i] == '\\') && (i > 0)) {
         while ((path[i + 1] == '\\') || (path[i + 1] == '/')) {
            (void)memmove(path + i + 1, path + i + 2, strlen(path + i + 1));
         }
      }
   }
}


static int
mg_wcscasecmp(const wchar_t *s1, const wchar_t *s2)
{
   int diff;

   do {
      diff = tolower(*s1) - tolower(*s2);
      s1++;
      s2++;
   } while ((diff == 0) && (s1[-1] != '\0'));

   return diff;
}


/* Encode 'path' which is assumed UTF-8 string, into UNICODE string.
 * wbuf and wbuf_len is a target buffer and its length. */
static void
path_to_unicode(const struct mg_connection *conn,
                const char *path,
                wchar_t *wbuf,
                size_t wbuf_len)
{
   char buf[PATH_MAX], buf2[PATH_MAX];
   wchar_t wbuf2[W_PATH_MAX + 1];
   DWORD long_len, err;
   int (*fcompare)(const wchar_t *, const wchar_t *) = mg_wcscasecmp;

   mg_strlcpy(buf, path, sizeof(buf));
   change_slashes_to_backslashes(buf);

   /* Convert to Unicode and back. If doubly-converted string does not
    * match the original, something is fishy, reject. */
   memset(wbuf, 0, wbuf_len * sizeof(wchar_t));
   MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, (int)wbuf_len);
   WideCharToMultiByte(
       CP_UTF8, 0, wbuf, (int)wbuf_len, buf2, sizeof(buf2), NULL, NULL);
   if (strcmp(buf, buf2) != 0) {
      wbuf[0] = L'\0';
   }

   /* Windows file systems are not case sensitive, but you can still use
    * uppercase and lowercase letters (on all modern file systems).
    * The server can check if the URI uses the same upper/lowercase
    * letters an the file system, effectively making Windows servers
    * case sensitive (like Linux servers are). It is still not possible
    * to use two files with the same name in different cases on Windows
    * (like /a and /A) - this would be possible in Linux.
    * As a default, Windows is not case sensitive, but the case sensitive
    * file name check can be activated by an additional configuration. */
   if (conn) {
      if (conn->dom_ctx->config[CASE_SENSITIVE_FILES]
          && !mg_strcasecmp(conn->dom_ctx->config[CASE_SENSITIVE_FILES],
                            "yes")) {
         /* Use case sensitive compare function */
         fcompare = wcscmp;
      }
   }
   (void)conn; /* conn is currently unused */

#if !defined(_WIN32_WCE)
   /* Only accept a full file path, not a Windows short (8.3) path. */
   memset(wbuf2, 0, ARRAY_SIZE(wbuf2) * sizeof(wchar_t));
   long_len = GetLongPathNameW(wbuf, wbuf2, ARRAY_SIZE(wbuf2) - 1);
   if (long_len == 0) {
      err = GetLastError();
      if (err == ERROR_FILE_NOT_FOUND) {
         /* File does not exist. This is not always a problem here. */
         return;
      }
   }
   if ((long_len >= ARRAY_SIZE(wbuf2)) || (fcompare(wbuf, wbuf2) != 0)) {
      /* Short name is used. */
      wbuf[0] = L'\0';
   }
#else
   (void)long_len;
   (void)wbuf2;
   (void)err;

   if (strchr(path, '~')) {
      wbuf[0] = L'\0';
   }
#endif
}


/* Windows happily opens files with some garbage at the end of file name.
 * For example, fopen("a.cgi    ", "r") on Windows successfully opens
 * "a.cgi", despite one would expect an error back.
 * This function returns non-0 if path ends with some garbage. */
static int
path_cannot_disclose_cgi(const char *path)
{
   static const char *allowed_last_characters = "_-";
   int last = path[strlen(path) - 1];
   return isalnum(last) || strchr(allowed_last_characters, last) != NULL;
}


static int
mg_stat(const struct mg_connection *conn,
        const char *path,
        struct mg_file_stat *filep)
{
   wchar_t wbuf[W_PATH_MAX];
   WIN32_FILE_ATTRIBUTE_DATA info;
   time_t creation_time;

   if (!filep) {
      return 0;
   }
   memset(filep, 0, sizeof(*filep));

   if (conn && is_file_in_memory(conn, path)) {
      /* filep->is_directory = 0; filep->gzipped = 0; .. already done by
       * memset */

      /* Quick fix (for 1.9.x): */
      /* mg_stat must fill all fields, also for files in memory */
      struct mg_file tmp_file = STRUCT_FILE_INITIALIZER;
      open_file_in_memory(conn, path, &tmp_file, MG_FOPEN_MODE_NONE);
      filep->size = tmp_file.stat.size;
      filep->location = 2;
      /* TODO: for 1.10: restructure how files in memory are handled */

      /* The "file in memory" feature is a candidate for deletion.
       * Please join the discussion at
       * https://groups.google.com/forum/#!topic/civetweb/h9HT4CmeYqI
       */

      filep->last_modified = time(NULL); /* TODO */
      /* last_modified = now ... assumes the file may change during
       * runtime,
       * so every mg_fopen call may return different data */
      /* last_modified = conn->phys_ctx.start_time;
       * May be used it the data does not change during runtime. This
       * allows
       * browser caching. Since we do not know, we have to assume the file
       * in memory may change. */
      return 1;
   }

   path_to_unicode(conn, path, wbuf, ARRAY_SIZE(wbuf));
   if (GetFileAttributesExW(wbuf, GetFileExInfoStandard, &info) != 0) {
      filep->size = MAKEUQUAD(info.nFileSizeLow, info.nFileSizeHigh);
      filep->last_modified =
          SYS2UNIX_TIME(info.ftLastWriteTime.dwLowDateTime,
                        info.ftLastWriteTime.dwHighDateTime);

      /* On Windows, the file creation time can be higher than the
       * modification time, e.g. when a file is copied.
       * Since the Last-Modified timestamp is used for caching
       * it should be based on the most recent timestamp. */
      creation_time = SYS2UNIX_TIME(info.ftCreationTime.dwLowDateTime,
                                    info.ftCreationTime.dwHighDateTime);
      if (creation_time > filep->last_modified) {
         filep->last_modified = creation_time;
      }

      filep->is_directory = info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;
      /* If file name is fishy, reset the file structure and return
       * error.
       * Note it is important to reset, not just return the error, cause
       * functions like is_file_opened() check the struct. */
      if (!filep->is_directory && !path_cannot_disclose_cgi(path)) {
         memset(filep, 0, sizeof(*filep));
         return 0;
      }

      return 1;
   }

   return 0;
}


static int
mg_remove(const struct mg_connection *conn, const char *path)
{
   wchar_t wbuf[W_PATH_MAX];
   path_to_unicode(conn, path, wbuf, ARRAY_SIZE(wbuf));
   return DeleteFileW(wbuf) ? 0 : -1;
}


static int
mg_mkdir(const struct mg_connection *conn, const char *path, int mode)
{
   wchar_t wbuf[W_PATH_MAX];
   (void)mode;
   path_to_unicode(conn, path, wbuf, ARRAY_SIZE(wbuf));
   return CreateDirectoryW(wbuf, NULL) ? 0 : -1;
}


/* Create substitutes for POSIX functions in Win32. */

#if defined(GCC_DIAGNOSTIC)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif


/* Implementation of POSIX opendir/closedir/readdir for Windows. */
FUNCTION_MAY_BE_UNUSED
static DIR *
mg_opendir(const struct mg_connection *conn, const char *name)
{
   DIR *dir = NULL;
   wchar_t wpath[W_PATH_MAX];
   DWORD attrs;

   if (name == NULL) {
      SetLastError(ERROR_BAD_ARGUMENTS);
   } else if ((dir = (DIR *)mg_malloc(sizeof(*dir))) == NULL) {
      SetLastError(ERROR_NOT_ENOUGH_MEMORY);
   } else {
      path_to_unicode(conn, name, wpath, ARRAY_SIZE(wpath));
      attrs = GetFileAttributesW(wpath);
      if ((wcslen(wpath) + 2 < ARRAY_SIZE(wpath)) && (attrs != 0xFFFFFFFF)
          && ((attrs & FILE_ATTRIBUTE_DIRECTORY) != 0)) {
         (void)wcscat(wpath, L"\\*");
         dir->handle = FindFirstFileW(wpath, &dir->info);
         dir->result.d_name[0] = '\0';
      } else {
         mg_free(dir);
         dir = NULL;
      }
   }

   return dir;
}


FUNCTION_MAY_BE_UNUSED
static int
mg_closedir(DIR *dir)
{
   int result = 0;

   if (dir != NULL) {
      if (dir->handle != INVALID_HANDLE_VALUE)
         result = FindClose(dir->handle) ? 0 : -1;

      mg_free(dir);
   } else {
      result = -1;
      SetLastError(ERROR_BAD_ARGUMENTS);
   }

   return result;
}


FUNCTION_MAY_BE_UNUSED
static struct dirent *
mg_readdir(DIR *dir)
{
   struct dirent *result = 0;

   if (dir) {
      if (dir->handle != INVALID_HANDLE_VALUE) {
         result = &dir->result;
         (void)WideCharToMultiByte(CP_UTF8,
                                   0,
                                   dir->info.cFileName,
                                   -1,
                                   result->d_name,
                                   sizeof(result->d_name),
                                   NULL,
                                   NULL);

         if (!FindNextFileW(dir->handle, &dir->info)) {
            (void)FindClose(dir->handle);
            dir->handle = INVALID_HANDLE_VALUE;
         }

      } else {
         SetLastError(ERROR_FILE_NOT_FOUND);
      }
   } else {
      SetLastError(ERROR_BAD_ARGUMENTS);
   }

   return result;
}


#if !defined(HAVE_POLL)
#define POLLIN (1)  /* Data ready - read will not block. */
#define POLLPRI (2) /* Priority data ready. */
#define POLLOUT (4) /* Send queue not full - write will not block. */

FUNCTION_MAY_BE_UNUSED
static int
poll(struct pollfd *pfd, unsigned int n, int milliseconds)
{
   struct timeval tv;
   fd_set rset;
   fd_set wset;
   unsigned int i;
   int result;
   SOCKET maxfd = 0;

   memset(&tv, 0, sizeof(tv));
   tv.tv_sec = milliseconds / 1000;
   tv.tv_usec = (milliseconds % 1000) * 1000;
   FD_ZERO(&rset);
   FD_ZERO(&wset);

   for (i = 0; i < n; i++) {
      if (pfd[i].events & POLLIN) {
         FD_SET((SOCKET)pfd[i].fd, &rset);
      } else if (pfd[i].events & POLLOUT) {
         FD_SET((SOCKET)pfd[i].fd, &wset);
      }
      pfd[i].revents = 0;

      if (pfd[i].fd > maxfd) {
         maxfd = pfd[i].fd;
      }
   }

   if ((result = select((int)maxfd + 1, &rset, &wset, NULL, &tv)) > 0) {
      for (i = 0; i < n; i++) {
         if (FD_ISSET(pfd[i].fd, &rset)) {
            pfd[i].revents |= POLLIN;
         }
         if (FD_ISSET(pfd[i].fd, &wset)) {
            pfd[i].revents |= POLLOUT;
         }
      }
   }

   /* We should subtract the time used in select from remaining
    * "milliseconds", in particular if called from mg_poll with a
    * timeout quantum.
    * Unfortunately, the remaining time is not stored in "tv" in all
    * implementations, so the result in "tv" must be considered undefined.
    * See http://man7.org/linux/man-pages/man2/select.2.html */

   return result;
}
#endif /* HAVE_POLL */


#if defined(GCC_DIAGNOSTIC)
/* Enable unused function warning again */
#pragma GCC diagnostic pop
#endif


static void
set_close_on_exec(SOCKET sock, struct mg_connection *conn /* may be null */)
{
   (void)conn; /* Unused. */
#if defined(_WIN32_WCE)
   (void)sock;
#else
   (void)SetHandleInformation((HANDLE)(intptr_t)sock, HANDLE_FLAG_INHERIT, 0);
#endif
}


int
mg_start_thread(mg_thread_func_t f, void *p)
{
#if defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1)
   /* Compile-time option to control stack size, e.g.
    * -DUSE_STACK_SIZE=16384
    */
   return ((_beginthread((void(__cdecl *)(void *))f, USE_STACK_SIZE, p)
            == ((uintptr_t)(-1L)))
               ? -1
               : 0);
#else
   return (
       (_beginthread((void(__cdecl *)(void *))f, 0, p) == ((uintptr_t)(-1L)))
           ? -1
           : 0);
#endif /* defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1) */
}


/* Start a thread storing the thread context. */
static int
mg_start_thread_with_id(unsigned(__stdcall *f)(void *),
                        void *p,
                        pthread_t *threadidptr)
{
   uintptr_t uip;
   HANDLE threadhandle;
   int result = -1;

   uip = _beginthreadex(NULL, 0, (unsigned(__stdcall *)(void *))f, p, 0, NULL);
   threadhandle = (HANDLE)uip;
   if ((uip != (uintptr_t)(-1L)) && (threadidptr != NULL)) {
      *threadidptr = threadhandle;
      result = 0;
   }

   return result;
}


/* Wait for a thread to finish. */
static int
mg_join_thread(pthread_t threadid)
{
   int result;
   DWORD dwevent;

   result = -1;
   dwevent = WaitForSingleObject(threadid, (DWORD)INFINITE);
   if (dwevent == WAIT_FAILED) {
      DEBUG_TRACE("WaitForSingleObject() failed, error %d", ERRNO);
   } else {
      if (dwevent == WAIT_OBJECT_0) {
         CloseHandle(threadid);
         result = 0;
      }
   }

   return result;
}

#if !defined(NO_SSL_DL) && !defined(NO_SSL)
/* If SSL is loaded dynamically, dlopen/dlclose is required. */
/* Create substitutes for POSIX functions in Win32. */

#if defined(GCC_DIAGNOSTIC)
/* Show no warning in case system functions are not used. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#endif


FUNCTION_MAY_BE_UNUSED
static HANDLE
dlopen(const char *dll_name, int flags)
{
   wchar_t wbuf[W_PATH_MAX];
   (void)flags;
   path_to_unicode(NULL, dll_name, wbuf, ARRAY_SIZE(wbuf));
   return LoadLibraryW(wbuf);
}


FUNCTION_MAY_BE_UNUSED
static int
dlclose(void *handle)
{
   int result;

   if (FreeLibrary((HMODULE)handle) != 0) {
      result = 0;
   } else {
      result = -1;
   }

   return result;
}


#if defined(GCC_DIAGNOSTIC)
/* Enable unused function warning again */
#pragma GCC diagnostic pop
#endif

#endif


#if !defined(NO_CGI)
#define SIGKILL (0)


static int
kill(pid_t pid, int sig_num)
{
   (void)TerminateProcess((HANDLE)pid, (UINT)sig_num);
   (void)CloseHandle((HANDLE)pid);
   return 0;
}


#if !defined(WNOHANG)
#define WNOHANG (1)
#endif


static pid_t
waitpid(pid_t pid, int *status, int flags)
{
   DWORD timeout = INFINITE;
   DWORD waitres;

   (void)status; /* Currently not used by any client here */

   if ((flags | WNOHANG) == WNOHANG) {
      timeout = 0;
   }

   waitres = WaitForSingleObject((HANDLE)pid, timeout);
   if (waitres == WAIT_OBJECT_0) {
      return pid;
   }
   if (waitres == WAIT_TIMEOUT) {
      return 0;
   }
   return (pid_t)-1;
}


static void
trim_trailing_whitespaces(char *s)
{
   char *e = s + strlen(s) - 1;
   while ((e > s) && isspace(*(unsigned char *)e)) {
      *e-- = '\0';
   }
}


static pid_t
spawn_process(struct mg_connection *conn,
              const char *prog,
              char *envblk,
              char *envp[],
              int fdin[2],
              int fdout[2],
              int fderr[2],
              const char *dir)
{
   HANDLE me;
   char *p, *interp, full_interp[PATH_MAX], full_dir[PATH_MAX],
       cmdline[PATH_MAX], buf[PATH_MAX];
   int truncated;
   struct mg_file file = STRUCT_FILE_INITIALIZER;
   STARTUPINFOA si;
   PROCESS_INFORMATION pi = {0};

   (void)envp;

   memset(&si, 0, sizeof(si));
   si.cb = sizeof(si);

   si.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
   si.wShowWindow = SW_HIDE;

   me = GetCurrentProcess();
   DuplicateHandle(me,
                   (HANDLE)_get_osfhandle(fdin[0]),
                   me,
                   &si.hStdInput,
                   0,
                   TRUE,
                   DUPLICATE_SAME_ACCESS);
   DuplicateHandle(me,
                   (HANDLE)_get_osfhandle(fdout[1]),
                   me,
                   &si.hStdOutput,
                   0,
                   TRUE,
                   DUPLICATE_SAME_ACCESS);
   DuplicateHandle(me,
                   (HANDLE)_get_osfhandle(fderr[1]),
                   me,
                   &si.hStdError,
                   0,
                   TRUE,
                   DUPLICATE_SAME_ACCESS);

   /* Mark handles that should not be inherited. See
    * https://msdn.microsoft.com/en-us/library/windows/desktop/ms682499%28v=vs.85%29.aspx
    */
   SetHandleInformation((HANDLE)_get_osfhandle(fdin[1]),
                        HANDLE_FLAG_INHERIT,
                        0);
   SetHandleInformation((HANDLE)_get_osfhandle(fdout[0]),
                        HANDLE_FLAG_INHERIT,
                        0);
   SetHandleInformation((HANDLE)_get_osfhandle(fderr[0]),
                        HANDLE_FLAG_INHERIT,
                        0);

   /* If CGI file is a script, try to read the interpreter line */
   interp = conn->dom_ctx->config[CGI_INTERPRETER];
   if (interp == NULL) {
      buf[0] = buf[1] = '\0';

      /* Read the first line of the script into the buffer */
      mg_snprintf(
          conn, &truncated, cmdline, sizeof(cmdline), "%s/%s", dir, prog);

      if (truncated) {
         pi.hProcess = (pid_t)-1;
         goto spawn_cleanup;
      }

      if (mg_fopen(conn, cmdline, MG_FOPEN_MODE_READ, &file)) {
#if defined(MG_USE_OPEN_FILE)
         p = (char *)file.access.membuf;
#else
         p = (char *)NULL;
#endif
         mg_fgets(buf, sizeof(buf), &file, &p);
         (void)mg_fclose(&file.access); /* ignore error on read only file */
         buf[sizeof(buf) - 1] = '\0';
      }

      if ((buf[0] == '#') && (buf[1] == '!')) {
         trim_trailing_whitespaces(buf + 2);
      } else {
         buf[2] = '\0';
      }
      interp = buf + 2;
   }

   if (interp[0] != '\0') {
      GetFullPathNameA(interp, sizeof(full_interp), full_interp, NULL);
      interp = full_interp;
   }
   GetFullPathNameA(dir, sizeof(full_dir), full_dir, NULL);

   if (interp[0] != '\0') {
      mg_snprintf(conn,
                  &truncated,
                  cmdline,
                  sizeof(cmdline),
                  "\"%s\" \"%s\\%s\"",
                  interp,
                  full_dir,
                  prog);
   } else {
      mg_snprintf(conn,
                  &truncated,
                  cmdline,
                  sizeof(cmdline),
                  "\"%s\\%s\"",
                  full_dir,
                  prog);
   }

   if (truncated) {
      pi.hProcess = (pid_t)-1;
      goto spawn_cleanup;
   }

   DEBUG_TRACE("Running [%s]", cmdline);
   if (CreateProcessA(NULL,
                      cmdline,
                      NULL,
                      NULL,
                      TRUE,
                      CREATE_NEW_PROCESS_GROUP,
                      envblk,
                      NULL,
                      &si,
                      &pi)
       == 0) {
      mg_cry_internal(
          conn, "%s: CreateProcess(%s): %ld", __func__, cmdline, (long)ERRNO);
      pi.hProcess = (pid_t)-1;
      /* goto spawn_cleanup; */
   }

spawn_cleanup:
   (void)CloseHandle(si.hStdOutput);
   (void)CloseHandle(si.hStdError);
   (void)CloseHandle(si.hStdInput);
   if (pi.hThread != NULL) {
      (void)CloseHandle(pi.hThread);
   }

   return (pid_t)pi.hProcess;
}
#endif /* !NO_CGI */


static int
set_blocking_mode(SOCKET sock)
{
   unsigned long non_blocking = 0;
   return ioctlsocket(sock, (long)FIONBIO, &non_blocking);
}

static int
set_non_blocking_mode(SOCKET sock)
{
   unsigned long non_blocking = 1;
   return ioctlsocket(sock, (long)FIONBIO, &non_blocking);
}

#else

static int
mg_stat(const struct mg_connection *conn,
        const char *path,
        struct mg_file_stat *filep)
{
   struct stat st;
   if (!filep) {
      return 0;
   }
   memset(filep, 0, sizeof(*filep));

   if (conn && is_file_in_memory(conn, path)) {

      /* Quick fix (for 1.9.x): */
      /* mg_stat must fill all fields, also for files in memory */
      struct mg_file tmp_file = STRUCT_FILE_INITIALIZER;
      open_file_in_memory(conn, path, &tmp_file, MG_FOPEN_MODE_NONE);
      filep->size = tmp_file.stat.size;
      filep->last_modified = time(NULL);
      filep->location = 2;
      /* TODO: remove legacy "files in memory" feature */

      return 1;
   }

   if (0 == stat(path, &st)) {
      filep->size = (uint64_t)(st.st_size);
      filep->last_modified = st.st_mtime;
      filep->is_directory = S_ISDIR(st.st_mode);
      return 1;
   }

   return 0;
}


static void
set_close_on_exec(SOCKET fd, struct mg_connection *conn /* may be null */)
{
   if (fcntl(fd, F_SETFD, FD_CLOEXEC) != 0) {
      if (conn) {
         mg_cry_internal(conn,
                         "%s: fcntl(F_SETFD FD_CLOEXEC) failed: %s",
                         __func__,
                         strerror(ERRNO));
      }
   }
}


int
mg_start_thread(mg_thread_func_t func, void *param)
{
   pthread_t thread_id;
   pthread_attr_t attr;
   int result;

   (void)pthread_attr_init(&attr);
   (void)pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

#if defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1)
   /* Compile-time option to control stack size,
    * e.g. -DUSE_STACK_SIZE=16384 */
   (void)pthread_attr_setstacksize(&attr, USE_STACK_SIZE);
#endif /* defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1) */

   result = pthread_create(&thread_id, &attr, func, param);
   pthread_attr_destroy(&attr);

   return result;
}


/* Start a thread storing the thread context. */
static int
mg_start_thread_with_id(mg_thread_func_t func,
                        void *param,
                        pthread_t *threadidptr)
{
   pthread_t thread_id;
   pthread_attr_t attr;
   int result;

   (void)pthread_attr_init(&attr);

#if defined(USE_STACK_SIZE) && (USE_STACK_SIZE > 1)
   /* Compile-time option to control stack size,
    * e.g. -DUSE_STACK_SIZE=16384 */
   (void)pthread_attr_setstacksize(&attr, USE_STACK_SIZE);
#endif /* defined(USE_STACK_SIZE) && USE_STACK_SIZE > 1 */

   result = pthread_create(&thread_id, &attr, func, param);
   pthread_attr_destroy(&attr);
   if ((result == 0) && (threadidptr != NULL)) {
      *threadidptr = thread_id;
   }
   return result;
}


/* Wait for a thread to finish. */
static int
mg_join_thread(pthread_t threadid)
{
   int result;

   result = pthread_join(threadid, NULL);
   return result;
}


#if !defined(NO_CGI)
static pid_t
spawn_process(struct mg_connection *conn,
              const char *prog,
              char *envblk,
              char *envp[],
              int fdin[2],
              int fdout[2],
              int fderr[2],
              const char *dir)
{
   pid_t pid;
   const char *interp;

   (void)envblk;

   if (conn == NULL) {
      return 0;
   }

   if ((pid = fork()) == -1) {
      /* Parent */
      mg_send_http_error(conn,
                         500,
                         "Error: Creating CGI process\nfork(): %s",
                         strerror(ERRNO));
   } else if (pid == 0) {
      /* Child */
      if (chdir(dir) != 0) {
         mg_cry_internal(
             conn, "%s: chdir(%s): %s", __func__, dir, strerror(ERRNO));
      } else if (dup2(fdin[0], 0) == -1) {
         mg_cry_internal(conn,
                         "%s: dup2(%d, 0): %s",
                         __func__,
                         fdin[0],
                         strerror(ERRNO));
      } else if (dup2(fdout[1], 1) == -1) {
         mg_cry_internal(conn,
                         "%s: dup2(%d, 1): %s",
                         __func__,
                         fdout[1],
                         strerror(ERRNO));
      } else if (dup2(fderr[1], 2) == -1) {
         mg_cry_internal(conn,
                         "%s: dup2(%d, 2): %s",
                         __func__,
                         fderr[1],
                         strerror(ERRNO));
      } else {
         /* Keep stderr and stdout in two different pipes.
          * Stdout will be sent back to the client,
          * stderr should go into a server error log. */
         (void)close(fdin[0]);
         (void)close(fdout[1]);
         (void)close(fderr[1]);

         /* Close write end fdin and read end fdout and fderr */
         (void)close(fdin[1]);
         (void)close(fdout[0]);
         (void)close(fderr[0]);

         /* After exec, all signal handlers are restored to their default
          * values, with one exception of SIGCHLD. According to
          * POSIX.1-2001 and Linux's implementation, SIGCHLD's handler
          * will leave unchanged after exec if it was set to be ignored.
          * Restore it to default action. */
         signal(SIGCHLD, SIG_DFL);

         interp = conn->dom_ctx->config[CGI_INTERPRETER];
         if (interp == NULL) {
            (void)execle(prog, prog, NULL, envp);
            mg_cry_internal(conn,
                            "%s: execle(%s): %s",
                            __func__,
                            prog,
                            strerror(ERRNO));
         } else {
            (void)execle(interp, interp, prog, NULL, envp);
            mg_cry_internal(conn,
                            "%s: execle(%s %s): %s",
                            __func__,
                            interp,
                            prog,
                            strerror(ERRNO));
         }
      }
      exit(EXIT_FAILURE);
   }

   return pid;
}
#endif /* !NO_CGI */


static int
set_non_blocking_mode(SOCKET sock)
{
   int flags = fcntl(sock, F_GETFL, 0);
   if (flags < 0) {
      return -1;
   }

   if (fcntl(sock, F_SETFL, (flags | O_NONBLOCK)) < 0) {
      return -1;
   }
   return 0;
}

static int
set_blocking_mode(SOCKET sock)
{
   int flags = fcntl(sock, F_GETFL, 0);
   if (flags < 0) {
      return -1;
   }

   if (fcntl(sock, F_SETFL, flags & (~(int)(O_NONBLOCK))) < 0) {
      return -1;
   }
   return 0;
}
#endif /* _WIN32 / else */

/* End of initial operating system specific define block. */


/* Get a random number (independent of C rand function) */
static uint64_t
get_random(void)
{
   static uint64_t lfsr = 0; /* Linear feedback shift register */
   static uint64_t lcg = 0;  /* Linear congruential generator */
   uint64_t now = mg_get_current_time_ns();

   if (lfsr == 0) {
      /* lfsr will be only 0 if has not been initialized,
       * so this code is called only once. */
      lfsr = mg_get_current_time_ns();
      lcg = mg_get_current_time_ns();
   } else {
      /* Get the next step of both random number generators. */
      lfsr = (lfsr >> 1)
             | ((((lfsr >> 0) ^ (lfsr >> 1) ^ (lfsr >> 3) ^ (lfsr >> 4)) & 1)
                << 63);
      lcg = lcg * 6364136223846793005LL + 1442695040888963407LL;
   }

   /* Combining two pseudo-random number generators and a high resolution
    * part
    * of the current server time will make it hard (impossible?) to guess
    * the
    * next number. */
   return (lfsr ^ lcg ^ now);
}


static int
mg_poll(struct pollfd *pfd,
        unsigned int n,
        int milliseconds,
        volatile int *stop_server)
{
   /* Call poll, but only for a maximum time of a few seconds.
    * This will allow to stop the server after some seconds, instead
    * of having to wait for a long socket timeout. */
   int ms_now = SOCKET_TIMEOUT_QUANTUM; /* Sleep quantum in ms */

   do {
      int result;

      if (*stop_server) {
         /* Shut down signal */
         return -2;
      }

      if ((milliseconds >= 0) && (milliseconds < ms_now)) {
         ms_now = milliseconds;
      }

      result = poll(pfd, n, ms_now);
      if (result != 0) {
         /* Poll returned either success (1) or error (-1).
          * Forward both to the caller. */
         return result;
      }

      /* Poll returned timeout (0). */
      if (milliseconds > 0) {
         milliseconds -= ms_now;
      }

   } while (milliseconds != 0);

   /* timeout: return 0 */
   return 0;
}


/* Write data to the IO channel - opened file descriptor, socket or SSL
 * descriptor.
 * Return value:
 *  >=0 .. number of bytes successfully written
 *   -1 .. timeout
 *   -2 .. error
 */
static int
push_inner(struct mg_context *ctx,
           FILE *fp,
           SOCKET sock,
           SSL *ssl,
           const char *buf,
           int len,
           double timeout)
{
   uint64_t start = 0, now = 0, timeout_ns = 0;
   int n, err;
   unsigned ms_wait = SOCKET_TIMEOUT_QUANTUM; /* Sleep quantum in ms */

#if defined(_WIN32)
   typedef int len_t;
#else
   typedef size_t len_t;
#endif

   if (timeout > 0) {
      now = mg_get_current_time_ns();
      start = now;
      timeout_ns = (uint64_t)(timeout * 1.0E9);
   }

   if (ctx == NULL) {
      return -2;
   }

#if defined(NO_SSL)
   if (ssl) {
      return -2;
   }
#endif

   /* Try to read until it succeeds, fails, times out, or the server
    * shuts down. */
   for (;;) {

#if !defined(NO_SSL)
      if (ssl != NULL) {
         n = SSL_write(ssl, buf, len);
         if (n <= 0) {
            err = SSL_get_error(ssl, n);
            if ((err == SSL_ERROR_SYSCALL) && (n == -1)) {
               err = ERRNO;
            } else if ((err == SSL_ERROR_WANT_READ)
                       || (err == SSL_ERROR_WANT_WRITE)) {
               n = 0;
            } else {
               DEBUG_TRACE("SSL_write() failed, error %d", err);
               return -2;
            }
         } else {
            err = 0;
         }
      } else
#endif
          if (fp != NULL) {
         n = (int)fwrite(buf, 1, (size_t)len, fp);
         if (ferror(fp)) {
            n = -1;
            err = ERRNO;
         } else {
            err = 0;
         }
      } else {
         n = (int)send(sock, buf, (len_t)len, MSG_NOSIGNAL);
         err = (n < 0) ? ERRNO : 0;
#if defined(_WIN32)
         if (err == WSAEWOULDBLOCK) {
            err = 0;
            n = 0;
         }
#else
         if (err == EWOULDBLOCK) {
            err = 0;
            n = 0;
         }
#endif
         if (n < 0) {
            /* shutdown of the socket at client side */
            return -2;
         }
      }

      if (ctx->stop_flag) {
         return -2;
      }

      if ((n > 0) || ((n == 0) && (len == 0))) {
         /* some data has been read, or no data was requested */
         return n;
      }
      if (n < 0) {
         /* socket error - check errno */
         DEBUG_TRACE("send() failed, error %d", err);

         /* TODO (mid): error handling depending on the error code.
          * These codes are different between Windows and Linux.
          * Currently there is no problem with failing send calls,
          * if there is a reproducible situation, it should be
          * investigated in detail.
          */
         return -2;
      }

      /* Only in case n=0 (timeout), repeat calling the write function */

      /* If send failed, wait before retry */
      if (fp != NULL) {
         /* For files, just wait a fixed time.
          * Maybe it helps, maybe not. */
         mg_sleep(5);
      } else {
         /* For sockets, wait for the socket using poll */
         struct pollfd pfd[1];
         int pollres;

         pfd[0].fd = sock;
         pfd[0].events = POLLOUT;
         pollres = mg_poll(pfd, 1, (int)(ms_wait), &(ctx->stop_flag));
         if (ctx->stop_flag) {
            return -2;
         }
         if (pollres > 0) {
            continue;
         }
      }

      if (timeout > 0) {
         now = mg_get_current_time_ns();
         if ((now - start) > timeout_ns) {
            /* Timeout */
            break;
         }
      }
   }

   (void)err; /* Avoid unused warning if NO_SSL is set and DEBUG_TRACE is not
                 used */

   return -1;
}


static int64_t
push_all(struct mg_context *ctx,
         FILE *fp,
         SOCKET sock,
         SSL *ssl,
         const char *buf,
         int64_t len)
{
   double timeout = -1.0;
   int64_t n, nwritten = 0;

   if (ctx == NULL) {
      return -1;
   }

   if (ctx->dd.config[REQUEST_TIMEOUT]) {
      timeout = atoi(ctx->dd.config[REQUEST_TIMEOUT]) / 1000.0;
   }

   while ((len > 0) && (ctx->stop_flag == 0)) {
      n = push_inner(ctx, fp, sock, ssl, buf + nwritten, (int)len, timeout);
      if (n < 0) {
         if (nwritten == 0) {
            nwritten = n; /* Propagate the error */
         }
         break;
      } else if (n == 0) {
         break; /* No more data to write */
      } else {
         nwritten += n;
         len -= n;
      }
   }

   return nwritten;
}


/* Read from IO channel - opened file descriptor, socket, or SSL descriptor.
 * Return value:
 *  >=0 .. number of bytes successfully read
 *   -1 .. timeout
 *   -2 .. error
 */
static int
pull_inner(FILE *fp,
           struct mg_connection *conn,
           char *buf,
           int len,
           double timeout)
{
   int nread, err = 0;

#if defined(_WIN32)
   typedef int len_t;
#else
   typedef size_t len_t;
#endif
#if !defined(NO_SSL)
   int ssl_pending;
#endif

   /* We need an additional wait loop around this, because in some cases
    * with TLSwe may get data from the socket but not from SSL_read.
    * In this case we need to repeat at least once.
    */

   if (fp != NULL) {
#if !defined(_WIN32_WCE)
      /* Use read() instead of fread(), because if we're reading from the
       * CGI pipe, fread() may block until IO buffer is filled up. We
       * cannot afford to block and must pass all read bytes immediately
       * to the client. */
      nread = (int)read(fileno(fp), buf, (size_t)len);
#else
      /* WinCE does not support CGI pipes */
      nread = (int)fread(buf, 1, (size_t)len, fp);
#endif
      err = (nread < 0) ? ERRNO : 0;
      if ((nread == 0) && (len > 0)) {
         /* Should get data, but got EOL */
         return -2;
      }

#if !defined(NO_SSL)
   } else if ((conn->ssl != NULL)
              && ((ssl_pending = SSL_pending(conn->ssl)) > 0)) {
      /* We already know there is no more data buffered in conn->buf
       * but there is more available in the SSL layer. So don't poll
       * conn->client.sock yet. */
      if (ssl_pending > len) {
         ssl_pending = len;
      }
      nread = SSL_read(conn->ssl, buf, ssl_pending);
      if (nread <= 0) {
         err = SSL_get_error(conn->ssl, nread);
         if ((err == SSL_ERROR_SYSCALL) && (nread == -1)) {
            err = ERRNO;
         } else if ((err == SSL_ERROR_WANT_READ)
                    || (err == SSL_ERROR_WANT_WRITE)) {
            nread = 0;
         } else {
            DEBUG_TRACE("SSL_read() failed, error %d", err);
            return -1;
         }
      } else {
         err = 0;
      }

   } else if (conn->ssl != NULL) {

      struct pollfd pfd[1];
      int pollres;

      pfd[0].fd = conn->client.sock;
      pfd[0].events = POLLIN;
      pollres = mg_poll(pfd,
                        1,
                        (int)(timeout * 1000.0),
                        &(conn->phys_ctx->stop_flag));
      if (conn->phys_ctx->stop_flag) {
         return -2;
      }
      if (pollres > 0) {
         nread = SSL_read(conn->ssl, buf, len);
         if (nread <= 0) {
            err = SSL_get_error(conn->ssl, nread);
            if ((err == SSL_ERROR_SYSCALL) && (nread == -1)) {
               err = ERRNO;
            } else if ((err == SSL_ERROR_WANT_READ)
                       || (err == SSL_ERROR_WANT_WRITE)) {
               nread = 0;
            } else {
               DEBUG_TRACE("SSL_read() failed, error %d", err);
               return -2;
            }
         } else {
            err = 0;
         }

      } else if (pollres < 0) {
         /* Error */
         return -2;
      } else {
         /* pollres = 0 means timeout */
         nread = 0;
      }
#endif

   } else {
      struct pollfd pfd[1];
      int pollres;

      pfd[0].fd = conn->client.sock;
      pfd[0].events = POLLIN;
      pollres = mg_poll(pfd,
                        1,
                        (int)(timeout * 1000.0),
                        &(conn->phys_ctx->stop_flag));
      if (conn->phys_ctx->stop_flag) {
         return -2;
      }
      if (pollres > 0) {
         nread = (int)recv(conn->client.sock, buf, (len_t)len, 0);
         err = (nread < 0) ? ERRNO : 0;
         if (nread <= 0) {
            /* shutdown of the socket at client side */
            return -2;
         }
      } else if (pollres < 0) {
         /* error callint poll */
         return -2;
      } else {
         /* pollres = 0 means timeout */
         nread = 0;
      }
   }

   if (conn->phys_ctx->stop_flag) {
      return -2;
   }

   if ((nread > 0) || ((nread == 0) && (len == 0))) {
      /* some data has been read, or no data was requested */
      return nread;
   }

   if (nread < 0) {
/* socket error - check errno */
#if defined(_WIN32)
      if (err == WSAEWOULDBLOCK) {
         /* TODO (low): check if this is still required */
         /* standard case if called from close_socket_gracefully */
         return -2;
      } else if (err == WSAETIMEDOUT) {
         /* TODO (low): check if this is still required */
         /* timeout is handled by the while loop  */
         return 0;
      } else if (err == WSAECONNABORTED) {
         /* See https://www.chilkatsoft.com/p/p_299.asp */
         return -2;
      } else {
         DEBUG_TRACE("recv() failed, error %d", err);
         return -2;
      }
#else
      /* TODO: POSIX returns either EAGAIN or EWOULDBLOCK in both cases,
       * if the timeout is reached and if the socket was set to non-
       * blocking in close_socket_gracefully, so we can not distinguish
       * here. We have to wait for the timeout in both cases for now.
       */
      if ((err == EAGAIN) || (err == EWOULDBLOCK) || (err == EINTR)) {
         /* TODO (low): check if this is still required */
         /* EAGAIN/EWOULDBLOCK:
          * standard case if called from close_socket_gracefully
          * => should return -1 */
         /* or timeout occurred
          * => the code must stay in the while loop */

         /* EINTR can be generated on a socket with a timeout set even
          * when SA_RESTART is effective for all relevant signals
          * (see signal(7)).
          * => stay in the while loop */
      } else {
         DEBUG_TRACE("recv() failed, error %d", err);
         return -2;
      }
#endif
   }

   /* Timeout occurred, but no data available. */
   return -1;
}


static int
pull_all(FILE *fp, struct mg_connection *conn, char *buf, int len)
{
   int n, nread = 0;
   double timeout = -1.0;
   uint64_t start_time = 0, now = 0, timeout_ns = 0;

   if (conn->dom_ctx->config[REQUEST_TIMEOUT]) {
      timeout = atoi(conn->dom_ctx->config[REQUEST_TIMEOUT]) / 1000.0;
   }
   if (timeout >= 0.0) {
      start_time = mg_get_current_time_ns();
      timeout_ns = (uint64_t)(timeout * 1.0E9);
   }

   while ((len > 0) && (conn->phys_ctx->stop_flag == 0)) {
      n = pull_inner(fp, conn, buf + nread, len, timeout);
      if (n == -2) {
         if (nread == 0) {
            nread = -1; /* Propagate the error */
         }
         break;
      } else if (n == -1) {
         /* timeout */
         if (timeout >= 0.0) {
            now = mg_get_current_time_ns();
            if ((now - start_time) <= timeout_ns) {
               continue;
            }
         }
         break;
      } else if (n == 0) {
         break; /* No more data to read */
      } else {
         conn->consumed_content += n;
         nread += n;
         len -= n;
      }
   }

   return nread;
}


static void
discard_unread_request_data(struct mg_connection *conn)
{
   char buf[MG_BUF_LEN];
   size_t to_read;
   int nread;

   if (conn == NULL) {
      return;
   }

   to_read = sizeof(buf);

   if (conn->is_chunked) {
      /* Chunked encoding: 3=chunk read completely
       * completely */
      while (conn->is_chunked != 3) {
         nread = mg_read(conn, buf, to_read);
         if (nread <= 0) {
            break;
         }
      }

   } else {
      /* Not chunked: content length is known */
      while (conn->consumed_content < conn->content_len) {
         if (to_read
             > (size_t)(conn->content_len - conn->consumed_content)) {
            to_read = (size_t)(conn->content_len - conn->consumed_content);
         }

         nread = mg_read(conn, buf, to_read);
         if (nread <= 0) {
            break;
         }
      }
   }
}


static int
mg_read_inner(struct mg_connection *conn, void *buf, size_t len)
{
   int64_t n, buffered_len, nread;
   int64_t len64 =
       (int64_t)((len > INT_MAX) ? INT_MAX : len); /* since the return value is
                                                    * int, we may not read more
                                                    * bytes */
   const char *body;

   if (conn == NULL) {
      return 0;
   }

   /* If Content-Length is not set for a request with body data
    * (e.g., a PUT or POST request), we do not know in advance
    * how much data should be read. */
   if (conn->consumed_content == 0) {
      if (conn->is_chunked == 1) {
         conn->content_len = len64;
         conn->is_chunked = 2;
      } else if (conn->content_len == -1) {
         /* The body data is completed when the connection
          * is closed. */
         conn->content_len = INT64_MAX;
         conn->must_close = 1;
      }
   }

   nread = 0;
   if (conn->consumed_content < conn->content_len) {
      /* Adjust number of bytes to read. */
      int64_t left_to_read = conn->content_len - conn->consumed_content;
      if (left_to_read < len64) {
         /* Do not read more than the total content length of the
          * request.
          */
         len64 = left_to_read;
      }

      /* Return buffered data */
      buffered_len = (int64_t)(conn->data_len) - (int64_t)conn->request_len
                     - conn->consumed_content;
      if (buffered_len > 0) {
         if (len64 < buffered_len) {
            buffered_len = len64;
         }
         body = conn->buf + conn->request_len + conn->consumed_content;
         memcpy(buf, body, (size_t)buffered_len);
         len64 -= buffered_len;
         conn->consumed_content += buffered_len;
         nread += buffered_len;
         buf = (char *)buf + buffered_len;
      }

      /* We have returned all buffered data. Read new data from the remote
       * socket.
       */
      if ((n = pull_all(NULL, conn, (char *)buf, (int)len64)) >= 0) {
         nread += n;
      } else {
         nread = ((nread > 0) ? nread : n);
      }
   }
   return (int)nread;
}


static char
mg_getc(struct mg_connection *conn)
{
   char c;
   if (conn == NULL) {
      return 0;
   }
   if (mg_read_inner(conn, &c, 1) <= 0) {
      return (char)0;
   }
   return c;
}


int
mg_read(struct mg_connection *conn, void *buf, size_t len)
{
   if (len > INT_MAX) {
      len = INT_MAX;
   }

   if (conn == NULL) {
      return 0;
   }

   if (conn->is_chunked) {
      size_t all_read = 0;

      while (len > 0) {
         if (conn->is_chunked == 3) {
            /* No more data left to read */
            return 0;
         }

         if (conn->chunk_remainder) {
            /* copy from the remainder of the last received chunk */
            long read_ret;
            size_t read_now =
                ((conn->chunk_remainder > len) ? (len)
                                               : (conn->chunk_remainder));

            conn->content_len += (int)read_now;
            read_ret =
                mg_read_inner(conn, (char *)buf + all_read, read_now);

            if (read_ret < 1) {
               /* read error */
               return -1;
            }

            all_read += (size_t)read_ret;
            conn->chunk_remainder -= (size_t)read_ret;
            len -= (size_t)read_ret;

            if (conn->chunk_remainder == 0) {
               /* Add data bytes in the current chunk have been read,
                * so we are expecting \r\n now. */
               char x1, x2;
               conn->content_len += 2;
               x1 = mg_getc(conn);
               x2 = mg_getc(conn);
               if ((x1 != '\r') || (x2 != '\n')) {
                  /* Protocol violation */
                  return -1;
               }
            }

         } else {
            /* fetch a new chunk */
            int i = 0;
            char lenbuf[64];
            char *end = 0;
            unsigned long chunkSize = 0;

            for (i = 0; i < ((int)sizeof(lenbuf) - 1); i++) {
               conn->content_len++;
               lenbuf[i] = mg_getc(conn);
               if ((i > 0) && (lenbuf[i] == '\r')
                   && (lenbuf[i - 1] != '\r')) {
                  continue;
               }
               if ((i > 1) && (lenbuf[i] == '\n')
                   && (lenbuf[i - 1] == '\r')) {
                  lenbuf[i + 1] = 0;
                  chunkSize = strtoul(lenbuf, &end, 16);
                  if (chunkSize == 0) {
                     /* regular end of content */
                     conn->is_chunked = 3;
                  }
                  break;
               }
               if (!isxdigit(lenbuf[i])) {
                  /* illegal character for chunk length */
                  return -1;
               }
            }
            if ((end == NULL) || (*end != '\r')) {
               /* chunksize not set correctly */
               return -1;
            }
            if (chunkSize == 0) {
               break;
            }

            conn->chunk_remainder = chunkSize;
         }
      }

      return (int)all_read;
   }
   return mg_read_inner(conn, buf, len);
}


int
mg_write(struct mg_connection *conn, const void *buf, size_t len)
{
   time_t now;
   int64_t n, total, allowed;

   if (conn == NULL) {
      return 0;
   }

   if (conn->throttle > 0) {
      if ((now = time(NULL)) != conn->last_throttle_time) {
         conn->last_throttle_time = now;
         conn->last_throttle_bytes = 0;
      }
      allowed = conn->throttle - conn->last_throttle_bytes;
      if (allowed > (int64_t)len) {
         allowed = (int64_t)len;
      }
      if ((total = push_all(conn->phys_ctx,
                            NULL,
                            conn->client.sock,
                            conn->ssl,
                            (const char *)buf,
                            (int64_t)allowed))
          == allowed) {
         buf = (const char *)buf + total;
         conn->last_throttle_bytes += total;
         while ((total < (int64_t)len) && (conn->phys_ctx->stop_flag == 0)) {
            allowed = (conn->throttle > ((int64_t)len - total))
                          ? (int64_t)len - total
                          : conn->throttle;
            if ((n = push_all(conn->phys_ctx,
                              NULL,
                              conn->client.sock,
                              conn->ssl,
                              (const char *)buf,
                              (int64_t)allowed))
                != allowed) {
               break;
            }
            sleep(1);
            conn->last_throttle_bytes = allowed;
            conn->last_throttle_time = time(NULL);
            buf = (const char *)buf + n;
            total += n;
         }
      }
   } else {
      total = push_all(conn->phys_ctx,
                       NULL,
                       conn->client.sock,
                       conn->ssl,
                       (const char *)buf,
                       (int64_t)len);
   }
   if (total > 0) {
      conn->num_bytes_sent += total;
   }
   return (int)total;
}


/* Send a chunk, if "Transfer-Encoding: chunked" is used */
int
mg_send_chunk(struct mg_connection *conn,
              const char *chunk,
              unsigned int chunk_len)
{
   char lenbuf[16];
   size_t lenbuf_len;
   int ret;
   int t;

   /* First store the length information in a text buffer. */
   sprintf(lenbuf, "%x\r\n", chunk_len);
   lenbuf_len = strlen(lenbuf);

   /* Then send length information, chunk and terminating \r\n. */
   ret = mg_write(conn, lenbuf, lenbuf_len);
   if (ret != (int)lenbuf_len) {
      return -1;
   }
   t = ret;

   ret = mg_write(conn, chunk, chunk_len);
   if (ret != (int)chunk_len) {
      return -1;
   }
   t += ret;

   ret = mg_write(conn, "\r\n", 2);
   if (ret != 2) {
      return -1;
   }
   t += ret;

   return t;
}


#if defined(GCC_DIAGNOSTIC)
/* This block forwards format strings to printf implementations,
 * so we need to disable the format-nonliteral warning. */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-nonliteral"
#endif


/* Alternative alloc_vprintf() for non-compliant C runtimes */
static int
alloc_vprintf2(char **buf, const char *fmt, va_list ap)
{
   va_list ap_copy;
   size_t size = MG_BUF_LEN / 4;
   int len = -1;

   *buf = NULL;
   while (len < 0) {
      if (*buf) {
         mg_free(*buf);
      }

      size *= 4;
      *buf = (char *)mg_malloc(size);
      if (!*buf) {
         break;
      }

      va_copy(ap_copy, ap);
      len = vsnprintf_impl(*buf, size - 1, fmt, ap_copy);
      va_end(ap_copy);
      (*buf)[size - 1] = 0;
   }

   return len;
}


/* Print message to buffer. If buffer is large enough to hold the message,
 * return buffer. If buffer is to small, allocate large enough buffer on
 * heap,
 * and return allocated buffer. */
static int
alloc_vprintf(char **out_buf,
              char *prealloc_buf,
              size_t prealloc_size,
              const char *fmt,
              va_list ap)
{
   va_list ap_copy;
   int len;

   /* Windows is not standard-compliant, and vsnprintf() returns -1 if
    * buffer is too small. Also, older versions of msvcrt.dll do not have
    * _vscprintf().  However, if size is 0, vsnprintf() behaves correctly.
    * Therefore, we make two passes: on first pass, get required message
    * length.
    * On second pass, actually print the message. */
   va_copy(ap_copy, ap);
   len = vsnprintf_impl(NULL, 0, fmt, ap_copy);
   va_end(ap_copy);

   if (len < 0) {
      /* C runtime is not standard compliant, vsnprintf() returned -1.
       * Switch to alternative code path that uses incremental
       * allocations.
       */
      va_copy(ap_copy, ap);
      len = alloc_vprintf2(out_buf, fmt, ap_copy);
      va_end(ap_copy);

   } else if ((size_t)(len) >= prealloc_size) {
      /* The pre-allocated buffer not large enough. */
      /* Allocate a new buffer. */
      *out_buf = (char *)mg_malloc((size_t)(len) + 1);
      if (!*out_buf) {
         /* Allocation failed. Return -1 as "out of memory" error. */
         return -1;
      }
      /* Buffer allocation successful. Store the string there. */
      va_copy(ap_copy, ap);
      IGNORE_UNUSED_RESULT(
          vsnprintf_impl(*out_buf, (size_t)(len) + 1, fmt, ap_copy));
      va_end(ap_copy);

   } else {
      /* The pre-allocated buffer is large enough.
       * Use it to store the string and return the address. */
      va_copy(ap_copy, ap);
      IGNORE_UNUSED_RESULT(
          vsnprintf_impl(prealloc_buf, prealloc_size, fmt, ap_copy));
      va_end(ap_copy);
      *out_buf = prealloc_buf;
   }

   return len;
}


#if defined(GCC_DIAGNOSTIC)
/* Enable format-nonliteral warning again. */
#pragma GCC diagnostic pop
#endif


static int
mg_vprintf(struct mg_connection *conn, const char *fmt, va_list ap)
{
   char mem[MG_BUF_LEN];
   char *buf = NULL;
   int len;

   if ((len = alloc_vprintf(&buf, mem, sizeof(mem), fmt, ap)) > 0) {
      len = mg_write(conn, buf, (size_t)len);
   }
   if ((buf != mem) && (buf != NULL)) {
      mg_free(buf);
   }

   return len;
}


int
mg_printf(struct mg_connection *conn, const char *fmt, ...)
{
   va_list ap;
   int result;

   va_start(ap, fmt);
   result = mg_vprintf(conn, fmt, ap);
   va_end(ap);

   return result;
}


int
mg_url_decode(const char *src,
              int src_len,
              char *dst,
              int dst_len,
              int is_form_url_encoded)
{
   int i, j, a, b;
#define HEXTOI(x) (isdigit(x) ? (x - '0') : (x - 'W'))

   for (i = j = 0; (i < src_len) && (j < (dst_len - 1)); i++, j++) {
      if ((i < src_len - 2) && (src[i] == '%')
          && isxdigit(*(const unsigned char *)(src + i + 1))
          && isxdigit(*(const unsigned char *)(src + i + 2))) {
         a = tolower(*(const unsigned char *)(src + i + 1));
         b = tolower(*(const unsigned char *)(src + i + 2));
         dst[j] = (char)((HEXTOI(a) << 4) | HEXTOI(b));
         i += 2;
      } else if (is_form_url_encoded && (src[i] == '+')) {
         dst[j] = ' ';
      } else {
         dst[j] = src[i];
      }
   }

   dst[j] = '\0'; /* Null-terminate the destination */

   return (i >= src_len) ? j : -1;
}


int
mg_get_var(const char *data,
           size_t data_len,
           const char *name,
           char *dst,
           size_t dst_len)
{
   return mg_get_var2(data, data_len, name, dst, dst_len, 0);
}


int
mg_get_var2(const char *data,
            size_t data_len,
            const char *name,
            char *dst,
            size_t dst_len,
            size_t occurrence)
{
   const char *p, *e, *s;
   size_t name_len;
   int len;

   if ((dst == NULL) || (dst_len == 0)) {
      len = -2;
   } else if ((data == NULL) || (name == NULL) || (data_len == 0)) {
      len = -1;
      dst[0] = '\0';
   } else {
      name_len = strlen(name);
      e = data + data_len;
      len = -1;
      dst[0] = '\0';

      /* data is "var1=val1&var2=val2...". Find variable first */
      for (p = data; p + name_len < e; p++) {
         if (((p == data) || (p[-1] == '&')) && (p[name_len] == '=')
             && !mg_strncasecmp(name, p, name_len) && 0 == occurrence--) {
            /* Point p to variable value */
            p += name_len + 1;

            /* Point s to the end of the value */
            s = (const char *)memchr(p, '&', (size_t)(e - p));
            if (s == NULL) {
               s = e;
            }
            DEBUG_ASSERT(s >= p);
            if (s < p) {
               return -3;
            }

            /* Decode variable into destination buffer */
            len = mg_url_decode(p, (int)(s - p), dst, (int)dst_len, 1);

            /* Redirect error code from -1 to -2 (destination buffer too
             * small). */
            if (len == -1) {
               len = -2;
            }
            break;
         }
      }
   }

   return len;
}


/* HCP24: some changes to compare hole var_name */
int
mg_get_cookie(const char *cookie_header,
              const char *var_name,
              char *dst,
              size_t dst_size)
{
   const char *s, *p, *end;
   int name_len, len = -1;

   if ((dst == NULL) || (dst_size == 0)) {
      return -2;
   }

   dst[0] = '\0';
   if ((var_name == NULL) || ((s = cookie_header) == NULL)) {
      return -1;
   }

   name_len = (int)strlen(var_name);
   end = s + strlen(s);
   for (; (s = mg_strcasestr(s, var_name)) != NULL; s += name_len) {
      if (s[name_len] == '=') {
         /* HCP24: now check is it a substring or a full cookie name */
         if ((s == cookie_header) || (s[-1] == ' ')) {
            s += name_len + 1;
            if ((p = strchr(s, ' ')) == NULL) {
               p = end;
            }
            if (p[-1] == ';') {
               p--;
            }
            if ((*s == '"') && (p[-1] == '"') && (p > s + 1)) {
               s++;
               p--;
            }
            if ((size_t)(p - s) < dst_size) {
               len = (int)(p - s);
               mg_strlcpy(dst, s, (size_t)len + 1);
            } else {
               len = -3;
            }
            break;
         }
      }
   }
   return len;
}


#if defined(USE_WEBSOCKET) || defined(USE_LUA)
static void
base64_encode(const unsigned char *src, int src_len, char *dst)
{
   static const char *b64 =
       "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
   int i, j, a, b, c;

   for (i = j = 0; i < src_len; i += 3) {
      a = src[i];
      b = ((i + 1) >= src_len) ? 0 : src[i + 1];
      c = ((i + 2) >= src_len) ? 0 : src[i + 2];

      dst[j++] = b64[a >> 2];
      dst[j++] = b64[((a & 3) << 4) | (b >> 4)];
      if (i + 1 < src_len) {
         dst[j++] = b64[(b & 15) << 2 | (c >> 6)];
      }
      if (i + 2 < src_len) {
         dst[j++] = b64[c & 63];
      }
   }
   while (j % 4 != 0) {
      dst[j++] = '=';
   }
   dst[j++] = '\0';
}
#endif


#if defined(USE_LUA)
static unsigned char
b64reverse(char letter)
{
   if ((letter >= 'A') && (letter <= 'Z')) {
      return letter - 'A';
   }
   if ((letter >= 'a') && (letter <= 'z')) {
      return letter - 'a' + 26;
   }
   if ((letter >= '0') && (letter <= '9')) {
      return letter - '0' + 52;
   }
   if (letter == '+') {
      return 62;
   }
   if (letter == '/') {
      return 63;
   }
   if (letter == '=') {
      return 255; /* normal end */
   }
   return 254; /* error */
}


static int
base64_decode(const unsigned char *src, int src_len, char *dst, size_t *dst_len)
{
   int i;
   unsigned char a, b, c, d;

   *dst_len = 0;

   for (i = 0; i < src_len; i += 4) {
      a = b64reverse(src[i]);
      if (a >= 254) {
         return i;
      }

      b = b64reverse(((i + 1) >= src_len) ? 0 : src[i + 1]);
      if (b >= 254) {
         return i + 1;
      }

      c = b64reverse(((i + 2) >= src_len) ? 0 : src[i + 2]);
      if (c == 254) {
         return i + 2;
      }

      d = b64reverse(((i + 3) >= src_len) ? 0 : src[i + 3]);
      if (d == 254) {
         return i + 3;
      }

      dst[(*dst_len)++] = (a << 2) + (b >> 4);
      if (c != 255) {
         dst[(*dst_len)++] = (b << 4) + (c >> 2);
         if (d != 255) {
            dst[(*dst_len)++] = (c << 6) + d;
         }
      }
   }
   return -1;
}
#endif


static int
is_put_or_delete_method(const struct mg_connection *conn)
{
   if (conn) {
      const char *s = conn->request_info.request_method;
      return (s != NULL)
             && (!strcmp(s, "PUT") || !strcmp(s, "DELETE")
                 || !strcmp(s, "MKCOL") || !strcmp(s, "PATCH"));
   }
   return 0;
}


#if !defined(NO_FILES)
static int
extention_matches_script(
    struct mg_connection *conn, /* in: request (must be valid) */
    const char *filename        /* in: filename  (must be valid) */
)
{
#if !defined(NO_CGI)
   if (match_prefix(conn->dom_ctx->config[CGI_EXTENSIONS],
                    strlen(conn->dom_ctx->config[CGI_EXTENSIONS]),
                    filename)
       > 0) {
      return 1;
   }
#endif
#if defined(USE_LUA)
   if (match_prefix(conn->dom_ctx->config[LUA_SCRIPT_EXTENSIONS],
                    strlen(conn->dom_ctx->config[LUA_SCRIPT_EXTENSIONS]),
                    filename)
       > 0) {
      return 1;
   }
#endif
#if defined(USE_DUKTAPE)
   if (match_prefix(conn->dom_ctx->config[DUKTAPE_SCRIPT_EXTENSIONS],
                    strlen(conn->dom_ctx->config[DUKTAPE_SCRIPT_EXTENSIONS]),
                    filename)
       > 0) {
      return 1;
   }
#endif
   /* filename and conn could be unused, if all preocessor conditions
    * are false (no script language supported). */
   (void)filename;
   (void)conn;

   return 0;
}


/* For given directory path, substitute it to valid index file.
 * Return 1 if index file has been found, 0 if not found.
 * If the file is found, it's stats is returned in stp. */
static int
substitute_index_file(struct mg_connection *conn,
                      char *path,
                      size_t path_len,
                      struct mg_file_stat *filestat)
{
   const char *list = conn->dom_ctx->config[INDEX_FILES];
   struct vec filename_vec;
   size_t n = strlen(path);
   int found = 0;

   /* The 'path' given to us points to the directory. Remove all trailing
    * directory separator characters from the end of the path, and
    * then append single directory separator character. */
   while ((n > 0) && (path[n - 1] == '/')) {
      n--;
   }
   path[n] = '/';

   /* Traverse index files list. For each entry, append it to the given
    * path and see if the file exists. If it exists, break the loop */
   while ((list = next_option(list, &filename_vec, NULL)) != NULL) {
      /* Ignore too long entries that may overflow path buffer */
      if ((filename_vec.len + 1) > (path_len - (n + 1))) {
         continue;
      }

      /* Prepare full path to the index file */
      mg_strlcpy(path + n + 1, filename_vec.ptr, filename_vec.len + 1);

      /* Does it exist? */
      if (mg_stat(conn, path, filestat)) {
         /* Yes it does, break the loop */
         found = 1;
         break;
      }
   }

   /* If no index file exists, restore directory path */
   if (!found) {
      path[n] = '\0';
   }

   return found;
}
#endif


static void
interpret_uri(struct mg_connection *conn, /* in/out: request (must be valid) */
              char *filename,             /* out: filename */
              size_t filename_buf_len,    /* in: size of filename buffer */
              struct mg_file_stat *filestat, /* out: file status structure */
              int *is_found,                 /* out: file found (directly) */
              int *is_script_resource,       /* out: handled by a script? */
              int *is_websocket_request,     /* out: websocket connetion? */
              int *is_put_or_delete_request  /* out: put/delete a file? */
)
{
   char const *accept_encoding;

#if !defined(NO_FILES)
   const char *uri = conn->request_info.local_uri;
   const char *root = conn->dom_ctx->config[DOCUMENT_ROOT];
   const char *rewrite;
   struct vec a, b;
   ptrdiff_t match_len;
   char gz_path[PATH_MAX];
   int truncated;
#if !defined(NO_CGI) || defined(USE_LUA) || defined(USE_DUKTAPE)
   char *tmp_str;
   size_t tmp_str_len, sep_pos;
   int allow_substitute_script_subresources;
#endif
#else
   (void)filename_buf_len; /* unused if NO_FILES is defined */
#endif

   /* Step 1: Set all initially unknown outputs to zero */
   memset(filestat, 0, sizeof(*filestat));
   *filename = 0;
   *is_found = 0;
   *is_script_resource = 0;

   /* Step 2: Check if the request attempts to modify the file system */
   *is_put_or_delete_request = is_put_or_delete_method(conn);

/* Step 3: Check if it is a websocket request, and modify the document
 * root if required */
#if defined(USE_WEBSOCKET)
   *is_websocket_request = is_websocket_protocol(conn);
#if !defined(NO_FILES)
   if (*is_websocket_request && conn->dom_ctx->config[WEBSOCKET_ROOT]) {
      root = conn->dom_ctx->config[WEBSOCKET_ROOT];
   }
#endif /* !NO_FILES */
#else  /* USE_WEBSOCKET */
   *is_websocket_request = 0;
#endif /* USE_WEBSOCKET */

   /* Step 4: Check if gzip encoded response is allowed */
   conn->accept_gzip = 0;
   if ((accept_encoding = mg_get_header(conn, "Accept-Encoding")) != NULL) {
      if (strstr(accept_encoding, "gzip") != NULL) {
         conn->accept_gzip = 1;
      }
   }

#if !defined(NO_FILES)
   /* Step 5: If there is no root directory, don't look for files. */
   /* Note that root == NULL is a regular use case here. This occurs,
    * if all requests are handled by callbacks, so the WEBSOCKET_ROOT
    * config is not required. */
   if (root == NULL) {
      /* all file related outputs have already been set to 0, just return
       */
      return;
   }

   /* Step 6: Determine the local file path from the root path and the
    * request uri. */
   /* Using filename_buf_len - 1 because memmove() for PATH_INFO may shift
    * part of the path one byte on the right. */
   mg_snprintf(
       conn, &truncated, filename, filename_buf_len - 1, "%s%s", root, uri);

   if (truncated) {
      goto interpret_cleanup;
   }

   /* Step 7: URI rewriting */
   rewrite = conn->dom_ctx->config[URL_REWRITE_PATTERN];
   while ((rewrite = next_option(rewrite, &a, &b)) != NULL) {
      if ((match_len = match_prefix(a.ptr, a.len, uri)) > 0) {
         mg_snprintf(conn,
                     &truncated,
                     filename,
                     filename_buf_len - 1,
                     "%.*s%s",
                     (int)b.len,
                     b.ptr,
                     uri + match_len);
         break;
      }
   }

   if (truncated) {
      goto interpret_cleanup;
   }

   /* Step 8: Check if the file exists at the server */
   /* Local file path and name, corresponding to requested URI
    * is now stored in "filename" variable. */
   if (mg_stat(conn, filename, filestat)) {
      int uri_len = (int)strlen(uri);
      int is_uri_end_slash = (uri_len > 0) && (uri[uri_len - 1] == '/');

      /* 8.1: File exists. */
      *is_found = 1;

      /* 8.2: Check if it is a script type. */
      if (extention_matches_script(conn, filename)) {
         /* The request addresses a CGI resource, Lua script or
          * server-side javascript.
          * The URI corresponds to the script itself (like
          * /path/script.cgi), and there is no additional resource
          * path (like /path/script.cgi/something).
          * Requests that modify (replace or delete) a resource, like
          * PUT and DELETE requests, should replace/delete the script
          * file.
          * Requests that read or write from/to a resource, like GET and
          * POST requests, should call the script and return the
          * generated response. */
         *is_script_resource = (!*is_put_or_delete_request);
      }

      /* 8.3: If the request target is a directory, there could be
       * a substitute file (index.html, index.cgi, ...). */
      if (filestat->is_directory && is_uri_end_slash) {
         /* Use a local copy here, since substitute_index_file will
          * change the content of the file status */
         struct mg_file_stat tmp_filestat;
         memset(&tmp_filestat, 0, sizeof(tmp_filestat));

         if (substitute_index_file(
                 conn, filename, filename_buf_len, &tmp_filestat)) {

            /* Substitute file found. Copy stat to the output, then
             * check if the file is a script file */
            *filestat = tmp_filestat;

            if (extention_matches_script(conn, filename)) {
               /* Substitute file is a script file */
               *is_script_resource = 1;
            } else {
               /* Substitute file is a regular file */
               *is_script_resource = 0;
               *is_found = (mg_stat(conn, filename, filestat) ? 1 : 0);
            }
         }
         /* If there is no substitute file, the server could return
          * a directory listing in a later step */
      }
      return;
   }

   /* Step 9: Check for zipped files: */
   /* If we can't find the actual file, look for the file
    * with the same name but a .gz extension. If we find it,
    * use that and set the gzipped flag in the file struct
    * to indicate that the response need to have the content-
    * encoding: gzip header.
    * We can only do this if the browser declares support. */
   if (conn->accept_gzip) {
      mg_snprintf(
          conn, &truncated, gz_path, sizeof(gz_path), "%s.gz", filename);

      if (truncated) {
         goto interpret_cleanup;
      }

      if (mg_stat(conn, gz_path, filestat)) {
         if (filestat) {
            filestat->is_gzipped = 1;
            *is_found = 1;
         }
         /* Currently gz files can not be scripts. */
         return;
      }
   }

#if !defined(NO_CGI) || defined(USE_LUA) || defined(USE_DUKTAPE)
   /* Step 10: Script resources may handle sub-resources */
   /* Support PATH_INFO for CGI scripts. */
   tmp_str_len = strlen(filename);
   tmp_str = (char *)mg_malloc_ctx(tmp_str_len + PATH_MAX + 1, conn->phys_ctx);
   if (!tmp_str) {
      /* Out of memory */
      goto interpret_cleanup;
   }
   memcpy(tmp_str, filename, tmp_str_len + 1);

   /* Check config, if index scripts may have sub-resources */
   allow_substitute_script_subresources =
       !mg_strcasecmp(conn->dom_ctx->config[ALLOW_INDEX_SCRIPT_SUB_RES],
                      "yes");

   sep_pos = tmp_str_len;
   while (sep_pos > 0) {
      sep_pos--;
      if (tmp_str[sep_pos] == '/') {
         int is_script = 0, does_exist = 0;

         tmp_str[sep_pos] = 0;
         if (tmp_str[0]) {
            is_script = extention_matches_script(conn, tmp_str);
            does_exist = mg_stat(conn, tmp_str, filestat);
         }

         if (does_exist && is_script) {
            filename[sep_pos] = 0;
            memmove(filename + sep_pos + 2,
                    filename + sep_pos + 1,
                    strlen(filename + sep_pos + 1) + 1);
            conn->path_info = filename + sep_pos + 1;
            filename[sep_pos + 1] = '/';
            *is_script_resource = 1;
            *is_found = 1;
            break;
         }

         if (allow_substitute_script_subresources) {
            if (substitute_index_file(
                    conn, tmp_str, tmp_str_len + PATH_MAX, filestat)) {

               /* some intermediate directory has an index file */
               if (extention_matches_script(conn, tmp_str)) {

                  char *tmp_str2;

                  DEBUG_TRACE("Substitute script %s serving path %s",
                              tmp_str,
                              filename);

                  /* this index file is a script */
                  tmp_str2 = mg_strdup_ctx(filename + sep_pos + 1,
                                           conn->phys_ctx);
                  mg_snprintf(conn,
                              &truncated,
                              filename,
                              filename_buf_len,
                              "%s//%s",
                              tmp_str,
                              tmp_str2);
                  mg_free(tmp_str2);

                  if (truncated) {
                     mg_free(tmp_str);
                     goto interpret_cleanup;
                  }
                  sep_pos = strlen(tmp_str);
                  filename[sep_pos] = 0;
                  conn->path_info = filename + sep_pos + 1;
                  *is_script_resource = 1;
                  *is_found = 1;
                  break;

               } else {

                  DEBUG_TRACE("Substitute file %s serving path %s",
                              tmp_str,
                              filename);

                  /* non-script files will not have sub-resources */
                  filename[sep_pos] = 0;
                  conn->path_info = 0;
                  *is_script_resource = 0;
                  *is_found = 0;
                  break;
               }
            }
         }

         tmp_str[sep_pos] = '/';
      }
   }

   mg_free(tmp_str);

#endif /* !defined(NO_CGI) || defined(USE_LUA) || defined(USE_DUKTAPE) */
#endif /* !defined(NO_FILES) */
   return;

#if !defined(NO_FILES)
/* Reset all outputs */
interpret_cleanup:
   memset(filestat, 0, sizeof(*filestat));
   *filename = 0;
   *is_found = 0;
   *is_script_resource = 0;
   *is_websocket_request = 0;
   *is_put_or_delete_request = 0;
#endif /* !defined(NO_FILES) */
}


/* Check whether full request is buffered. Return:
 * -1  if request or response is malformed
 *  0  if request or response is not yet fully buffered
 * >0  actual request length, including last \r\n\r\n */
static int
get_http_header_len(const char *buf, int buflen)
{
   int i;
   for (i = 0; i < buflen; i++) {
      /* Do an unsigned comparison in some conditions below */
      const unsigned char c = ((const unsigned char *)buf)[i];

      if ((c < 128) && ((char)c != '\r') && ((char)c != '\n')
          && !isprint(c)) {
         /* abort scan as soon as one malformed character is found */
         return -1;
      }

      if (i < buflen - 1) {
         if ((buf[i] == '\n') && (buf[i + 1] == '\n')) {
            /* Two newline, no carriage return - not standard compliant,
             * but
             * it
             * should be accepted */
            return i + 2;
         }
      }

      if (i < buflen - 3) {
         if ((buf[i] == '\r') && (buf[i + 1] == '\n') && (buf[i + 2] == '\r')
             && (buf[i + 3] == '\n')) {
            /* Two \r\n - standard compliant */
            return i + 4;
         }
      }
   }

   return 0;
}


#if !defined(NO_CACHING)
/* Convert month to the month number. Return -1 on error, or month number */
static int
get_month_index(const char *s)
{
   size_t i;

   for (i = 0; i < ARRAY_SIZE(month_names); i++) {
      if (!strcmp(s, month_names[i])) {
         return (int)i;
      }
   }

   return -1;
}


/* Parse UTC date-time string, and return the corresponding time_t value. */
static time_t
parse_date_string(const char *datetime)
{
   char month_str[32] = {0};
   int second, minute, hour, day, month, year;
   time_t result = (time_t)0;
   struct tm tm;

   if ((sscanf(datetime,
               "%d/%3s/%d %d:%d:%d",
               &day,
               month_str,
               &year,
               &hour,
               &minute,
               &second)
        == 6)
       || (sscanf(datetime,
                  "%d %3s %d %d:%d:%d",
                  &day,
                  month_str,
                  &year,
                  &hour,
                  &minute,
                  &second)
           == 6)
       || (sscanf(datetime,
                  "%*3s, %d %3s %d %d:%d:%d",
                  &day,
                  month_str,
                  &year,
                  &hour,
                  &minute,
                  &second)
           == 6)
       || (sscanf(datetime,
                  "%d-%3s-%d %d:%d:%d",
                  &day,
                  month_str,
                  &year,
                  &hour,
                  &minute,
                  &second)
           == 6)) {
      month = get_month_index(month_str);
      if ((month >= 0) && (year >= 1970)) {
         memset(&tm, 0, sizeof(tm));
         tm.tm_year = year - 1900;
         tm.tm_mon = month;
         tm.tm_mday = day;
         tm.tm_hour = hour;
         tm.tm_min = minute;
         tm.tm_sec = second;
         result = timegm(&tm);
      }
   }

   return result;
}
#endif /* !NO_CACHING */


/* Protect against directory disclosure attack by removing '..',
 * excessive '/' and '\' characters */
static void
remove_double_dots_and_double_slashes(char *s)
{
   char *p = s;

   while ((s[0] == '.') && (s[1] == '.')) {
      s++;
   }

   while (*s != '\0') {
      *p++ = *s++;
      if ((s[-1] == '/') || (s[-1] == '\\')) {
         /* Skip all following slashes, backslashes and double-dots */
         while (s[0] != '\0') {
            if ((s[0] == '/') || (s[0] == '\\')) {
               s++;
            } else if ((s[0] == '.') && (s[1] == '.')) {
               s += 2;
            } else {
               break;
            }
         }
      }
   }
   *p = '\0';
}


static const struct {
   const char *extension;
   size_t ext_len;
   const char *mime_type;
} builtin_mime_types[] = {
    /* IANA registered MIME types
     * (http://www.iana.org/assignments/media-types)
     * application types */
    {".doc", 4, "application/msword"},
    {".eps", 4, "application/postscript"},
    {".exe", 4, "application/octet-stream"},
    {".js", 3, "application/javascript"},
    {".json", 5, "application/json"},
    {".pdf", 4, "application/pdf"},
    {".ps", 3, "application/postscript"},
    {".rtf", 4, "application/rtf"},
    {".xhtml", 6, "application/xhtml+xml"},
    {".xsl", 4, "application/xml"},
    {".xslt", 5, "application/xml"},

    /* fonts */
    {".ttf", 4, "application/font-sfnt"},
    {".cff", 4, "application/font-sfnt"},
    {".otf", 4, "application/font-sfnt"},
    {".aat", 4, "application/font-sfnt"},
    {".sil", 4, "application/font-sfnt"},
    {".pfr", 4, "application/font-tdpfr"},
    {".woff", 5, "application/font-woff"},

    /* audio */
    {".mp3", 4, "audio/mpeg"},
    {".oga", 4, "audio/ogg"},
    {".ogg", 4, "audio/ogg"},

    /* image */
    {".gif", 4, "image/gif"},
    {".ief", 4, "image/ief"},
    {".jpeg", 5, "image/jpeg"},
    {".jpg", 4, "image/jpeg"},
    {".jpm", 4, "image/jpm"},
    {".jpx", 4, "image/jpx"},
    {".png", 4, "image/png"},
    {".svg", 4, "image/svg+xml"},
    {".tif", 4, "image/tiff"},
    {".tiff", 5, "image/tiff"},

    /* model */
    {".wrl", 4, "model/vrml"},

    /* text */
    {".css", 4, "text/css"},
    {".csv", 4, "text/csv"},
    {".htm", 4, "text/html"},
    {".html", 5, "text/html"},
    {".sgm", 4, "text/sgml"},
    {".shtm", 5, "text/html"},
    {".shtml", 6, "text/html"},
    {".txt", 4, "text/plain"},
    {".xml", 4, "text/xml"},

    /* video */
    {".mov", 4, "video/quicktime"},
    {".mp4", 4, "video/mp4"},
    {".mpeg", 5, "video/mpeg"},
    {".mpg", 4, "video/mpeg"},
    {".ogv", 4, "video/ogg"},
    {".qt", 3, "video/quicktime"},

    /* not registered types
     * (http://reference.sitepoint.com/html/mime-types-full,
     * http://www.hansenb.pdx.edu/DMKB/dict/tutorials/mime_typ.php, ..) */
    {".arj", 4, "application/x-arj-compressed"},
    {".gz", 3, "application/x-gunzip"},
    {".rar", 4, "application/x-arj-compressed"},
    {".swf", 4, "application/x-shockwave-flash"},
    {".tar", 4, "application/x-tar"},
    {".tgz", 4, "application/x-tar-gz"},
    {".torrent", 8, "application/x-bittorrent"},
    {".ppt", 4, "application/x-mspowerpoint"},
    {".xls", 4, "application/x-msexcel"},
    {".zip", 4, "application/x-zip-compressed"},
    {".aac",
     4,
     "audio/aac"}, /* http://en.wikipedia.org/wiki/Advanced_Audio_Coding */
    {".aif", 4, "audio/x-aif"},
    {".m3u", 4, "audio/x-mpegurl"},
    {".mid", 4, "audio/x-midi"},
    {".ra", 3, "audio/x-pn-realaudio"},
    {".ram", 4, "audio/x-pn-realaudio"},
    {".wav", 4, "audio/x-wav"},
    {".bmp", 4, "image/bmp"},
    {".ico", 4, "image/x-icon"},
    {".pct", 4, "image/x-pct"},
    {".pict", 5, "image/pict"},
    {".rgb", 4, "image/x-rgb"},
    {".webm", 5, "video/webm"}, /* http://en.wikipedia.org/wiki/WebM */
    {".asf", 4, "video/x-ms-asf"},
    {".avi", 4, "video/x-msvideo"},
    {".m4v", 4, "video/x-m4v"},
    {NULL, 0, NULL}};


const char *
mg_get_builtin_mime_type(const char *path)
{
   const char *ext;
   size_t i, path_len;

   path_len = strlen(path);

   for (i = 0; builtin_mime_types[i].extension != NULL; i++) {
      ext = path + (path_len - builtin_mime_types[i].ext_len);
      if ((path_len > builtin_mime_types[i].ext_len)
          && (mg_strcasecmp(ext, builtin_mime_types[i].extension) == 0)) {
         return builtin_mime_types[i].mime_type;
      }
   }

   return "text/plain";
}


/* Look at the "path" extension and figure what mime type it has.
 * Store mime type in the vector. */
static void
get_mime_type(struct mg_connection *conn, const char *path, struct vec *vec)
{
   struct vec ext_vec, mime_vec;
   const char *list, *ext;
   size_t path_len;

   path_len = strlen(path);

   if ((conn == NULL) || (vec == NULL)) {
      if (vec != NULL) {
         memset(vec, '\0', sizeof(struct vec));
      }
      return;
   }

   /* Scan user-defined mime types first, in case user wants to
    * override default mime types. */
   list = conn->dom_ctx->config[EXTRA_MIME_TYPES];
   while ((list = next_option(list, &ext_vec, &mime_vec)) != NULL) {
      /* ext now points to the path suffix */
      ext = path + path_len - ext_vec.len;
      if (mg_strncasecmp(ext, ext_vec.ptr, ext_vec.len) == 0) {
         *vec = mime_vec;
         return;
      }
   }

   vec->ptr = mg_get_builtin_mime_type(path);
   vec->len = strlen(vec->ptr);
}


/* Stringify binary data. Output buffer must be twice as big as input,
 * because each byte takes 2 bytes in string representation */
static void
bin2str(char *to, const unsigned char *p, size_t len)
{
   static const char *hex = "0123456789abcdef";

   for (; len--; p++) {
      *to++ = hex[p[0] >> 4];
      *to++ = hex[p[0] & 0x0f];
   }
   *to = '\0';
}


/* Return stringified MD5 hash for list of strings. Buffer must be 33 bytes.
 */
char *
mg_md5(char buf[33], ...)
{
   md5_byte_t hash[16];
   const char *p;
   va_list ap;
   md5_state_t ctx;

   md5_init(&ctx);

   va_start(ap, buf);
   while ((p = va_arg(ap, const char *)) != NULL) {
      md5_append(&ctx, (const md5_byte_t *)p, strlen(p));
   }
   va_end(ap);

   md5_finish(&ctx, hash);
   bin2str(buf, hash, sizeof(hash));
   return buf;
}


/* Check the user's password, return 1 if OK */
static int
check_password(const char *method,
               const char *ha1,
               const char *uri,
               const char *nonce,
               const char *nc,
               const char *cnonce,
               const char *qop,
               const char *response)
{
   char ha2[32 + 1], expected_response[32 + 1];

   /* Some of the parameters may be NULL */
   if ((method == NULL) || (nonce == NULL) || (nc == NULL) || (cnonce == NULL)
       || (qop == NULL) || (response == NULL)) {
      return 0;
   }

   /* NOTE(lsm): due to a bug in MSIE, we do not compare the URI */
   if (strlen(response) != 32) {
      return 0;
   }

   mg_md5(ha2, method, ":", uri, NULL);
   mg_md5(expected_response,
          ha1,
          ":",
          nonce,
          ":",
          nc,
          ":",
          cnonce,
          ":",
          qop,
          ":",
          ha2,
          NULL);

   return mg_strcasecmp(response, expected_response) == 0;
}


/* Use the global passwords file, if specified by auth_gpass option,
 * or search for .htpasswd in the requested directory. */
static void
open_auth_file(struct mg_connection *conn,
               const char *path,
               struct mg_file *filep)
{
   if ((conn != NULL) && (conn->dom_ctx != NULL)) {
      char name[PATH_MAX];
      const char *p, *e,
          *gpass = conn->dom_ctx->config[GLOBAL_PASSWORDS_FILE];
      int truncated;

      if (gpass != NULL) {
         /* Use global passwords file */
         if (!mg_fopen(conn, gpass, MG_FOPEN_MODE_READ, filep)) {
#if defined(DEBUG)
            /* Use mg_cry_internal here, since gpass has been configured. */
            mg_cry_internal(conn, "fopen(%s): %s", gpass, strerror(ERRNO));
#endif
         }
         /* Important: using local struct mg_file to test path for
          * is_directory flag. If filep is used, mg_stat() makes it
          * appear as if auth file was opened.
          * TODO(mid): Check if this is still required after rewriting
          * mg_stat */
      } else if (mg_stat(conn, path, &filep->stat)
                 && filep->stat.is_directory) {
         mg_snprintf(conn,
                     &truncated,
                     name,
                     sizeof(name),
                     "%s/%s",
                     path,
                     PASSWORDS_FILE_NAME);

         if (truncated || !mg_fopen(conn, name, MG_FOPEN_MODE_READ, filep)) {
#if defined(DEBUG)
            /* Don't use mg_cry_internal here, but only a trace, since this
             * is
             * a typical case. It will occur for every directory
             * without a password file. */
            DEBUG_TRACE("fopen(%s): %s", name, strerror(ERRNO));
#endif
         }
      } else {
         /* Try to find .htpasswd in requested directory. */
         for (p = path, e = p + strlen(p) - 1; e > p; e--) {
            if (e[0] == '/') {
               break;
            }
         }
         mg_snprintf(conn,
                     &truncated,
                     name,
                     sizeof(name),
                     "%.*s/%s",
                     (int)(e - p),
                     p,
                     PASSWORDS_FILE_NAME);

         if (truncated || !mg_fopen(conn, name, MG_FOPEN_MODE_READ, filep)) {
#if defined(DEBUG)
            /* Don't use mg_cry_internal here, but only a trace, since this
             * is
             * a typical case. It will occur for every directory
             * without a password file. */
            DEBUG_TRACE("fopen(%s): %s", name, strerror(ERRNO));
#endif
         }
      }
   }
}


/* Parsed Authorization header */
struct ah {
   char *user, *uri, *cnonce, *response, *qop, *nc, *nonce;
};


/* Return 1 on success. Always initializes the ah structure. */
static int
parse_auth_header(struct mg_connection *conn,
                  char *buf,
                  size_t buf_size,
                  struct ah *ah)
{
   char *name, *value, *s;
   const char *auth_header;
   uint64_t nonce;

   if (!ah || !conn) {
      return 0;
   }

   (void)memset(ah, 0, sizeof(*ah));
   if (((auth_header = mg_get_header(conn, "Authorization")) == NULL)
       || mg_strncasecmp(auth_header, "Digest ", 7) != 0) {
      return 0;
   }

   /* Make modifiable copy of the auth header */
   (void)mg_strlcpy(buf, auth_header + 7, buf_size);
   s = buf;

   /* Parse authorization header */
   for (;;) {
      /* Gobble initial spaces */
      while (isspace(*(unsigned char *)s)) {
         s++;
      }
      name = skip_quoted(&s, "=", " ", 0);
      /* Value is either quote-delimited, or ends at first comma or space.
       */
      if (s[0] == '\"') {
         s++;
         value = skip_quoted(&s, "\"", " ", '\\');
         if (s[0] == ',') {
            s++;
         }
      } else {
         value = skip_quoted(&s, ", ", " ", 0); /* IE uses commas, FF uses
                                                 * spaces */
      }
      if (*name == '\0') {
         break;
      }

      if (!strcmp(name, "username")) {
         ah->user = value;
      } else if (!strcmp(name, "cnonce")) {
         ah->cnonce = value;
      } else if (!strcmp(name, "response")) {
         ah->response = value;
      } else if (!strcmp(name, "uri")) {
         ah->uri = value;
      } else if (!strcmp(name, "qop")) {
         ah->qop = value;
      } else if (!strcmp(name, "nc")) {
         ah->nc = value;
      } else if (!strcmp(name, "nonce")) {
         ah->nonce = value;
      }
   }

#if !defined(NO_NONCE_CHECK)
   /* Read the nonce from the response. */
   if (ah->nonce == NULL) {
      return 0;
   }
   s = NULL;
   nonce = strtoull(ah->nonce, &s, 10);
   if ((s == NULL) || (*s != 0)) {
      return 0;
   }

   /* Convert the nonce from the client to a number. */
   nonce ^= conn->dom_ctx->auth_nonce_mask;

   /* The converted number corresponds to the time the nounce has been
    * created. This should not be earlier than the server start. */
   /* Server side nonce check is valuable in all situations but one:
    * if the server restarts frequently, but the client should not see
    * that, so the server should accept nonces from previous starts. */
   /* However, the reasonable default is to not accept a nonce from a
    * previous start, so if anyone changed the access rights between
    * two restarts, a new login is required. */
   if (nonce < (uint64_t)conn->phys_ctx->start_time) {
      /* nonce is from a previous start of the server and no longer valid
       * (replay attack?) */
      return 0;
   }
   /* Check if the nonce is too high, so it has not (yet) been used by the
    * server. */
   if (nonce >= ((uint64_t)conn->phys_ctx->start_time
                 + conn->dom_ctx->nonce_count)) {
      return 0;
   }
#else
   (void)nonce;
#endif

   /* CGI needs it as REMOTE_USER */
   if (ah->user != NULL) {
      conn->request_info.remote_user =
          mg_strdup_ctx(ah->user, conn->phys_ctx);
   } else {
      return 0;
   }

   return 1;
}


static const char *
mg_fgets(char *buf, size_t size, struct mg_file *filep, char **p)
{
#if defined(MG_USE_OPEN_FILE)
   const char *eof;
   size_t len;
   const char *memend;
#else
   (void)p; /* parameter is unused */
#endif

   if (!filep) {
      return NULL;
   }

#if defined(MG_USE_OPEN_FILE)
   if ((filep->access.membuf != NULL) && (*p != NULL)) {
      memend = (const char *)&filep->access.membuf[filep->stat.size];
      /* Search for \n from p till the end of stream */
      eof = (char *)memchr(*p, '\n', (size_t)(memend - *p));
      if (eof != NULL) {
         eof += 1; /* Include \n */
      } else {
         eof = memend; /* Copy remaining data */
      }
      len =
          ((size_t)(eof - *p) > (size - 1)) ? (size - 1) : (size_t)(eof - *p);
      memcpy(buf, *p, len);
      buf[len] = '\0';
      *p += len;
      return len ? eof : NULL;
   } else /* filep->access.fp block below */
#endif
       if (filep->access.fp != NULL) {
      return fgets(buf, (int)size, filep->access.fp);
   } else {
      return NULL;
   }
}

/* Define the initial recursion depth for procesesing htpasswd files that
 * include other htpasswd
 * (or even the same) files.  It is not difficult to provide a file or files
 * s.t. they force civetweb
 * to infinitely recurse and then crash.
 */
#define INITIAL_DEPTH 9
#if INITIAL_DEPTH <= 0
#error Bad INITIAL_DEPTH for recursion, set to at least 1
#endif

struct read_auth_file_struct {
   struct mg_connection *conn;
   struct ah ah;
   const char *domain;
   char buf[256 + 256 + 40];
   const char *f_user;
   const char *f_domain;
   const char *f_ha1;
};


static int
read_auth_file(struct mg_file *filep,
               struct read_auth_file_struct *workdata,
               int depth)
{
   char *p = NULL /* init if MG_USE_OPEN_FILE is not set */;
   int is_authorized = 0;
   struct mg_file fp;
   size_t l;

   if (!filep || !workdata || (0 == depth)) {
      return 0;
   }

/* Loop over passwords file */
#if defined(MG_USE_OPEN_FILE)
   p = (char *)filep->access.membuf;
#endif
   while (mg_fgets(workdata->buf, sizeof(workdata->buf), filep, &p) != NULL) {
      l = strlen(workdata->buf);
      while (l > 0) {
         if (isspace(workdata->buf[l - 1])
             || iscntrl(workdata->buf[l - 1])) {
            l--;
            workdata->buf[l] = 0;
         } else
            break;
      }
      if (l < 1) {
         continue;
      }

      workdata->f_user = workdata->buf;

      if (workdata->f_user[0] == ':') {
         /* user names may not contain a ':' and may not be empty,
          * so lines starting with ':' may be used for a special purpose
          */
         if (workdata->f_user[1] == '#') {
            /* :# is a comment */
            continue;
         } else if (!strncmp(workdata->f_user + 1, "include=", 8)) {
            if (mg_fopen(workdata->conn,
                         workdata->f_user + 9,
                         MG_FOPEN_MODE_READ,
                         &fp)) {
               is_authorized = read_auth_file(&fp, workdata, depth - 1);
               (void)mg_fclose(
                   &fp.access); /* ignore error on read only file */

               /* No need to continue processing files once we have a
                * match, since nothing will reset it back
                * to 0.
                */
               if (is_authorized) {
                  return is_authorized;
               }
            } else {
               mg_cry_internal(workdata->conn,
                               "%s: cannot open authorization file: %s",
                               __func__,
                               workdata->buf);
            }
            continue;
         }
         /* everything is invalid for the moment (might change in the
          * future) */
         mg_cry_internal(workdata->conn,
                         "%s: syntax error in authorization file: %s",
                         __func__,
                         workdata->buf);
         continue;
      }

      workdata->f_domain = strchr(workdata->f_user, ':');
      if (workdata->f_domain == NULL) {
         mg_cry_internal(workdata->conn,
                         "%s: syntax error in authorization file: %s",
                         __func__,
                         workdata->buf);
         continue;
      }
      *(char *)(workdata->f_domain) = 0;
      (workdata->f_domain)++;

      workdata->f_ha1 = strchr(workdata->f_domain, ':');
      if (workdata->f_ha1 == NULL) {
         mg_cry_internal(workdata->conn,
                         "%s: syntax error in authorization file: %s",
                         __func__,
                         workdata->buf);
         continue;
      }
      *(char *)(workdata->f_ha1) = 0;
      (workdata->f_ha1)++;

      if (!strcmp(workdata->ah.user, workdata->f_user)
          && !strcmp(workdata->domain, workdata->f_domain)) {
         return check_password(workdata->conn->request_info.request_method,
                               workdata->f_ha1,
                               workdata->ah.uri,
                               workdata->ah.nonce,
                               workdata->ah.nc,
                               workdata->ah.cnonce,
                               workdata->ah.qop,
                               workdata->ah.response);
      }
   }

   return is_authorized;
}


/* Authorize against the opened passwords file. Return 1 if authorized. */
static int
authorize(struct mg_connection *conn, struct mg_file *filep, const char *realm)
{
   struct read_auth_file_struct workdata;
   char buf[MG_BUF_LEN];

   if (!conn || !conn->dom_ctx) {
      return 0;
   }

   memset(&workdata, 0, sizeof(workdata));
   workdata.conn = conn;

   if (!parse_auth_header(conn, buf, sizeof(buf), &workdata.ah)) {
      return 0;
   }

   if (realm) {
      workdata.domain = realm;
   } else {
      workdata.domain = conn->dom_ctx->config[AUTHENTICATION_DOMAIN];
   }

   return read_auth_file(filep, &workdata, INITIAL_DEPTH);
}


/* Public function to check http digest authentication header */
int
mg_check_digest_access_authentication(struct mg_connection *conn,
                                      const char *realm,
                                      const char *filename)
{
   struct mg_file file = STRUCT_FILE_INITIALIZER;
   int auth;

   if (!conn || !filename) {
      return -1;
   }
   if (!mg_fopen(conn, filename, MG_FOPEN_MODE_READ, &file)) {
      return -2;
   }

   auth = authorize(conn, &file, realm);

   mg_fclose(&file.access);

   return auth;
}


/* Return 1 if request is authorised, 0 otherwise. */
static int
check_authorization(struct mg_connection *conn, const char *path)
{
   char fname[PATH_MAX];
   struct vec uri_vec, filename_vec;
   const char *list;
   struct mg_file file = STRUCT_FILE_INITIALIZER;
   int authorized = 1, truncated;

   if (!conn || !conn->dom_ctx) {
      return 0;
   }

   list = conn->dom_ctx->config[PROTECT_URI];
   while ((list = next_option(list, &uri_vec, &filename_vec)) != NULL) {
      if (!memcmp(conn->request_info.local_uri, uri_vec.ptr, uri_vec.len)) {
         mg_snprintf(conn,
                     &truncated,
                     fname,
                     sizeof(fname),
                     "%.*s",
                     (int)filename_vec.len,
                     filename_vec.ptr);

         if (truncated
             || !mg_fopen(conn, fname, MG_FOPEN_MODE_READ, &file)) {
            mg_cry_internal(conn,
                            "%s: cannot open %s: %s",
                            __func__,
                            fname,
                            strerror(errno));
         }
         break;
      }
   }

   if (!is_file_opened(&file.access)) {
      open_auth_file(conn, path, &file);
   }

   if (is_file_opened(&file.access)) {
      authorized = authorize(conn, &file, NULL);
      (void)mg_fclose(&file.access); /* ignore error on read only file */
   }

   return authorized;
}


/* Internal function. Assumes conn is valid */
static void
send_authorization_request(struct mg_connection *conn, const char *realm)
{
   char date[64];
   time_t curtime = time(NULL);
   uint64_t nonce = (uint64_t)(conn->phys_ctx->start_time);

   if (!realm) {
      realm = conn->dom_ctx->config[AUTHENTICATION_DOMAIN];
   }

   (void)pthread_mutex_lock(&conn->phys_ctx->nonce_mutex);
   nonce += conn->dom_ctx->nonce_count;
   ++conn->dom_ctx->nonce_count;
   (void)pthread_mutex_unlock(&conn->phys_ctx->nonce_mutex);

   nonce ^= conn->dom_ctx->auth_nonce_mask;
   conn->status_code = 401;
   conn->must_close = 1;

   gmt_time_string(date, sizeof(date), &curtime);

   mg_printf(conn, "HTTP/1.1 401 Unauthorized\r\n");
   send_no_cache_header(conn);
   send_additional_header(conn);
   mg_printf(conn,
             "Date: %s\r\n"
             "Connection: %s\r\n"
             "Content-Length: 0\r\n"
             "WWW-Authenticate: Digest qop=\"auth\", realm=\"%s\", "
             "nonce=\"%" UINT64_FMT "\"\r\n\r\n",
             date,
             suggest_connection_header(conn),
             realm,
             nonce);
}


/* Interface function. Parameters are provided by the user, so do
 * at least some basic checks.
 */
int
mg_send_digest_access_authentication_request(struct mg_connection *conn,
                                             const char *realm)
{
   if (conn && conn->dom_ctx) {
      send_authorization_request(conn, realm);
      return 0;
   }
   return -1;
}


#if !defined(NO_FILES)
static int
is_authorized_for_put(struct mg_connection *conn)
{
   if (conn) {
      struct mg_file file = STRUCT_FILE_INITIALIZER;
      const char *passfile = conn->dom_ctx->config[PUT_DELETE_PASSWORDS_FILE];
      int ret = 0;

      if (passfile != NULL
          && mg_fopen(conn, passfile, MG_FOPEN_MODE_READ, &file)) {
         ret = authorize(conn, &file, NULL);
         (void)mg_fclose(&file.access); /* ignore error on read only file */
      }

      return ret;
   }
   return 0;
}
#endif


int
mg_modify_passwords_file(const char *fname,
                         const char *domain,
                         const char *user,
                         const char *pass)
{
   int found, i;
   char line[512], u[512] = "", d[512] = "", ha1[33], tmp[PATH_MAX + 8];
   FILE *fp, *fp2;

   found = 0;
   fp = fp2 = NULL;

   /* Regard empty password as no password - remove user record. */
   if ((pass != NULL) && (pass[0] == '\0')) {
      pass = NULL;
   }

   /* Other arguments must not be empty */
   if ((fname == NULL) || (domain == NULL) || (user == NULL)) {
      return 0;
   }

   /* Using the given file format, user name and domain must not contain
    * ':'
    */
   if (strchr(user, ':') != NULL) {
      return 0;
   }
   if (strchr(domain, ':') != NULL) {
      return 0;
   }

   /* Do not allow control characters like newline in user name and domain.
    * Do not allow excessively long names either. */
   for (i = 0; ((i < 255) && (user[i] != 0)); i++) {
      if (iscntrl(user[i])) {
         return 0;
      }
   }
   if (user[i]) {
      return 0;
   }
   for (i = 0; ((i < 255) && (domain[i] != 0)); i++) {
      if (iscntrl(domain[i])) {
         return 0;
      }
   }
   if (domain[i]) {
      return 0;
   }

   /* The maximum length of the path to the password file is limited */
   if ((strlen(fname) + 4) >= PATH_MAX) {
      return 0;
   }

   /* Create a temporary file name. Length has been checked before. */
   strcpy(tmp, fname);
   strcat(tmp, ".tmp");

   /* Create the file if does not exist */
   /* Use of fopen here is OK, since fname is only ASCII */
   if ((fp = fopen(fname, "a+")) != NULL) {
      (void)fclose(fp);
   }

   /* Open the given file and temporary file */
   if ((fp = fopen(fname, "r")) == NULL) {
      return 0;
   } else if ((fp2 = fopen(tmp, "w+")) == NULL) {
      fclose(fp);
      return 0;
   }

   /* Copy the stuff to temporary file */
   while (fgets(line, sizeof(line), fp) != NULL) {
      if (sscanf(line, "%255[^:]:%255[^:]:%*s", u, d) != 2) {
         continue;
      }
      u[255] = 0;
      d[255] = 0;

      if (!strcmp(u, user) && !strcmp(d, domain)) {
         found++;
         if (pass != NULL) {
            mg_md5(ha1, user, ":", domain, ":", pass, NULL);
            fprintf(fp2, "%s:%s:%s\n", user, domain, ha1);
         }
      } else {
         fprintf(fp2, "%s", line);
      }
   }

   /* If new user, just add it */
   if (!found && (pass != NULL)) {
      mg_md5(ha1, user, ":", domain, ":", pass, NULL);
      fprintf(fp2, "%s:%s:%s\n", user, domain, ha1);
   }

   /* Close files */
   fclose(fp);
   fclose(fp2);

   /* Put the temp file in place of real file */
   IGNORE_UNUSED_RESULT(remove(fname));
   IGNORE_UNUSED_RESULT(rename(tmp, fname));

   return 1;
}


static int
is_valid_port(unsigned long port)
{
   return (port <= 0xffff);
}


static int
mg_inet_pton(int af, const char *src, void *dst, size_t dstlen)
{
   struct addrinfo hints, *res, *ressave;
   int func_ret = 0;
   int gai_ret;

   memset(&hints, 0, sizeof(struct addrinfo));
   hints.ai_family = af;

   gai_ret = getaddrinfo(src, NULL, &hints, &res);
   if (gai_ret != 0) {
      /* gai_strerror could be used to convert gai_ret to a string */
      /* POSIX return values: see
       * http://pubs.opengroup.org/onlinepubs/9699919799/functions/freeaddrinfo.html
       */
      /* Windows return values: see
       * https://msdn.microsoft.com/en-us/library/windows/desktop/ms738520%28v=vs.85%29.aspx
       */
      return 0;
   }

   ressave = res;

   while (res) {
      if (dstlen >= (size_t)res->ai_addrlen) {
         memcpy(dst, res->ai_addr, res->ai_addrlen);
         func_ret = 1;
      }
      res = res->ai_next;
   }

   freeaddrinfo(ressave);
   return func_ret;
}


static int
connect_socket(struct mg_context *ctx /* may be NULL */,
               const char *host,
               int port,
               int use_ssl,
               char *ebuf,
               size_t ebuf_len,
               SOCKET *sock /* output: socket, must not be NULL */,
               union usa *sa /* output: socket address, must not be NULL  */
)
{
   int ip_ver = 0;
   int conn_ret = -1;
   int ret;
   *sock = INVALID_SOCKET;
   memset(sa, 0, sizeof(*sa));

   if (ebuf_len > 0) {
      *ebuf = 0;
   }

   if (host == NULL) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "NULL host");
      return 0;
   }

   if ((port <= 0) || !is_valid_port((unsigned)port)) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "invalid port");
      return 0;
   }

#if !defined(NO_SSL)
#if !defined(NO_SSL_DL)
#if defined(OPENSSL_API_1_1)
   if (use_ssl && (TLS_client_method == NULL)) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "SSL is not initialized");
      return 0;
   }
#else
   if (use_ssl && (SSLv23_client_method == NULL)) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "SSL is not initialized");
      return 0;
   }

#endif /* OPENSSL_API_1_1 */
#else
   (void)use_ssl;
#endif /* NO_SSL_DL */
#else
   (void)use_ssl;
#endif /* !defined(NO_SSL) */

   if (mg_inet_pton(AF_INET, host, &sa->sin, sizeof(sa->sin))) {
      sa->sin.sin_family = AF_INET;
      sa->sin.sin_port = htons((uint16_t)port);
      ip_ver = 4;
#if defined(USE_IPV6)
   } else if (mg_inet_pton(AF_INET6, host, &sa->sin6, sizeof(sa->sin6))) {
      sa->sin6.sin6_family = AF_INET6;
      sa->sin6.sin6_port = htons((uint16_t)port);
      ip_ver = 6;
   } else if (host[0] == '[') {
      /* While getaddrinfo on Windows will work with [::1],
       * getaddrinfo on Linux only works with ::1 (without []). */
      size_t l = strlen(host + 1);
      char *h = (l > 1) ? mg_strdup_ctx(host + 1, ctx) : NULL;
      if (h) {
         h[l - 1] = 0;
         if (mg_inet_pton(AF_INET6, h, &sa->sin6, sizeof(sa->sin6))) {
            sa->sin6.sin6_family = AF_INET6;
            sa->sin6.sin6_port = htons((uint16_t)port);
            ip_ver = 6;
         }
         mg_free(h);
      }
#endif
   }

   if (ip_ver == 0) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "host not found");
      return 0;
   }

   if (ip_ver == 4) {
      *sock = socket(PF_INET, SOCK_STREAM, 0);
   }
#if defined(USE_IPV6)
   else if (ip_ver == 6) {
      *sock = socket(PF_INET6, SOCK_STREAM, 0);
   }
#endif

   if (*sock == INVALID_SOCKET) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "socket(): %s",
                  strerror(ERRNO));
      return 0;
   }

   if (0 != set_non_blocking_mode(*sock)) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "Cannot set socket to non-blocking: %s",
                  strerror(ERRNO));
      closesocket(*sock);
      *sock = INVALID_SOCKET;
      return 0;
   }

   set_close_on_exec(*sock, fc(ctx));

   if (ip_ver == 4) {
      /* connected with IPv4 */
      conn_ret = connect(*sock,
                         (struct sockaddr *)((void *)&sa->sin),
                         sizeof(sa->sin));
   }
#if defined(USE_IPV6)
   else if (ip_ver == 6) {
      /* connected with IPv6 */
      conn_ret = connect(*sock,
                         (struct sockaddr *)((void *)&sa->sin6),
                         sizeof(sa->sin6));
   }
#endif

#if defined(_WIN32)
   if (conn_ret != 0) {
      DWORD err = WSAGetLastError(); /* could return WSAEWOULDBLOCK */
      conn_ret = (int)err;
#if !defined(EINPROGRESS)
#define EINPROGRESS (WSAEWOULDBLOCK) /* Winsock equivalent */
#endif                               /* if !defined(EINPROGRESS) */
   }
#endif

   if ((conn_ret != 0) && (conn_ret != EINPROGRESS)) {
      /* Data for getsockopt */
      int sockerr = -1;
      void *psockerr = &sockerr;

#if defined(_WIN32)
      int len = (int)sizeof(sockerr);
#else
      socklen_t len = (socklen_t)sizeof(sockerr);
#endif

      /* Data for poll */
      struct pollfd pfd[1];
      int pollres;
      int ms_wait = 10000; /* 10 second timeout */

      /* For a non-blocking socket, the connect sequence is:
       * 1) call connect (will not block)
       * 2) wait until the socket is ready for writing (select or poll)
       * 3) check connection state with getsockopt
       */
      pfd[0].fd = *sock;
      pfd[0].events = POLLOUT;
      pollres = mg_poll(pfd, 1, (int)(ms_wait), &(ctx->stop_flag));

      if (pollres != 1) {
         /* Not connected */
         mg_snprintf(NULL,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "connect(%s:%d): timeout",
                     host,
                     port);
         closesocket(*sock);
         *sock = INVALID_SOCKET;
         return 0;
      }

#if defined(_WIN32)
      ret = getsockopt(*sock, SOL_SOCKET, SO_ERROR, (char *)psockerr, &len);
#else
      ret = getsockopt(*sock, SOL_SOCKET, SO_ERROR, psockerr, &len);
#endif

      if ((ret != 0) || (sockerr != 0)) {
         /* Not connected */
         mg_snprintf(NULL,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "connect(%s:%d): error %s",
                     host,
                     port,
                     strerror(sockerr));
         closesocket(*sock);
         *sock = INVALID_SOCKET;
         return 0;
      }
   }

   return 1;
}


int
mg_url_encode(const char *src, char *dst, size_t dst_len)
{
   static const char *dont_escape = "._-$,;~()";
   static const char *hex = "0123456789abcdef";
   char *pos = dst;
   const char *end = dst + dst_len - 1;

   for (; ((*src != '\0') && (pos < end)); src++, pos++) {
      if (isalnum(*(const unsigned char *)src)
          || (strchr(dont_escape, *(const unsigned char *)src) != NULL)) {
         *pos = *src;
      } else if (pos + 2 < end) {
         pos[0] = '%';
         pos[1] = hex[(*(const unsigned char *)src) >> 4];
         pos[2] = hex[(*(const unsigned char *)src) & 0xf];
         pos += 2;
      } else {
         break;
      }
   }

   *pos = '\0';
   return (*src == '\0') ? (int)(pos - dst) : -1;
}

/* Return 0 on success, non-zero if an error occurs. */

static int
print_dir_entry(struct de *de)
{
   size_t hrefsize;
   char *href;
   char size[64], mod[64];
#if defined(REENTRANT_TIME)
   struct tm _tm;
   struct tm *tm = &_tm;
#else
   struct tm *tm;
#endif

   hrefsize = PATH_MAX * 3; /* worst case */
   href = (char *)mg_malloc(hrefsize);
   if (href == NULL) {
      return -1;
   }
   if (de->file.is_directory) {
      mg_snprintf(de->conn,
                  NULL, /* Buffer is big enough */
                  size,
                  sizeof(size),
                  "%s",
                  "[DIRECTORY]");
   } else {
      /* We use (signed) cast below because MSVC 6 compiler cannot
       * convert unsigned __int64 to double. Sigh. */
      if (de->file.size < 1024) {
         mg_snprintf(de->conn,
                     NULL, /* Buffer is big enough */
                     size,
                     sizeof(size),
                     "%d",
                     (int)de->file.size);
      } else if (de->file.size < 0x100000) {
         mg_snprintf(de->conn,
                     NULL, /* Buffer is big enough */
                     size,
                     sizeof(size),
                     "%.1fk",
                     (double)de->file.size / 1024.0);
      } else if (de->file.size < 0x40000000) {
         mg_snprintf(de->conn,
                     NULL, /* Buffer is big enough */
                     size,
                     sizeof(size),
                     "%.1fM",
                     (double)de->file.size / 1048576);
      } else {
         mg_snprintf(de->conn,
                     NULL, /* Buffer is big enough */
                     size,
                     sizeof(size),
                     "%.1fG",
                     (double)de->file.size / 1073741824);
      }
   }

   /* Note: mg_snprintf will not cause a buffer overflow above.
    * So, string truncation checks are not required here. */

#if defined(REENTRANT_TIME)
   localtime_r(&de->file.last_modified, tm);
#else
   tm = localtime(&de->file.last_modified);
#endif
   if (tm != NULL) {
      strftime(mod, sizeof(mod), "%d-%b-%Y %H:%M", tm);
   } else {
      mg_strlcpy(mod, "01-Jan-1970 00:00", sizeof(mod));
      mod[sizeof(mod) - 1] = '\0';
   }
   mg_url_encode(de->file_name, href, hrefsize);
   mg_printf(de->conn,
             "<tr><td><a href=\"%s%s%s\">%s%s</a></td>"
             "<td>&nbsp;%s</td><td>&nbsp;&nbsp;%s</td></tr>\n",
             de->conn->request_info.local_uri,
             href,
             de->file.is_directory ? "/" : "",
             de->file_name,
             de->file.is_directory ? "/" : "",
             mod,
             size);
   mg_free(href);
   return 0;
}


/* This function is called from send_directory() and used for
 * sorting directory entries by size, or name, or modification time.
 * On windows, __cdecl specification is needed in case if project is built
 * with __stdcall convention. qsort always requires __cdels callback. */
static int WINCDECL
compare_dir_entries(const void *p1, const void *p2)
{
   if (p1 && p2) {
      const struct de *a = (const struct de *)p1, *b = (const struct de *)p2;
      const char *query_string = a->conn->request_info.query_string;
      int cmp_result = 0;

      if (query_string == NULL) {
         query_string = "na";
      }

      if (a->file.is_directory && !b->file.is_directory) {
         return -1; /* Always put directories on top */
      } else if (!a->file.is_directory && b->file.is_directory) {
         return 1; /* Always put directories on top */
      } else if (*query_string == 'n') {
         cmp_result = strcmp(a->file_name, b->file_name);
      } else if (*query_string == 's') {
         cmp_result = (a->file.size == b->file.size)
                          ? 0
                          : ((a->file.size > b->file.size) ? 1 : -1);
      } else if (*query_string == 'd') {
         cmp_result =
             (a->file.last_modified == b->file.last_modified)
                 ? 0
                 : ((a->file.last_modified > b->file.last_modified) ? 1
                                                                    : -1);
      }

      return (query_string[1] == 'd') ? -cmp_result : cmp_result;
   }
   return 0;
}


static int
must_hide_file(struct mg_connection *conn, const char *path)
{
   if (conn && conn->dom_ctx) {
      const char *pw_pattern = "**" PASSWORDS_FILE_NAME "$";
      const char *pattern = conn->dom_ctx->config[HIDE_FILES];
      return (match_prefix(pw_pattern, strlen(pw_pattern), path) > 0)
             || ((pattern != NULL)
                 && (match_prefix(pattern, strlen(pattern), path) > 0));
   }
   return 0;
}


static int
scan_directory(struct mg_connection *conn,
               const char *dir,
               void *data,
               int (*cb)(struct de *, void *))
{
   char path[PATH_MAX];
   struct dirent *dp;
   DIR *dirp;
   struct de de;
   int truncated;

   if ((dirp = mg_opendir(conn, dir)) == NULL) {
      return 0;
   } else {
      de.conn = conn;

      while ((dp = mg_readdir(dirp)) != NULL) {
         /* Do not show current dir and hidden files */
         if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, "..")
             || must_hide_file(conn, dp->d_name)) {
            continue;
         }

         mg_snprintf(
             conn, &truncated, path, sizeof(path), "%s/%s", dir, dp->d_name);

         /* If we don't memset stat structure to zero, mtime will have
          * garbage and strftime() will segfault later on in
          * print_dir_entry(). memset is required only if mg_stat()
          * fails. For more details, see
          * http://code.google.com/p/mongoose/issues/detail?id=79 */
         memset(&de.file, 0, sizeof(de.file));

         if (truncated) {
            /* If the path is not complete, skip processing. */
            continue;
         }

         if (!mg_stat(conn, path, &de.file)) {
            mg_cry_internal(conn,
                            "%s: mg_stat(%s) failed: %s",
                            __func__,
                            path,
                            strerror(ERRNO));
         }
         de.file_name = dp->d_name;
         cb(&de, data);
      }
      (void)mg_closedir(dirp);
   }
   return 1;
}


#if !defined(NO_FILES)
static int
remove_directory(struct mg_connection *conn, const char *dir)
{
   char path[PATH_MAX];
   struct dirent *dp;
   DIR *dirp;
   struct de de;
   int truncated;
   int ok = 1;

   if ((dirp = mg_opendir(conn, dir)) == NULL) {
      return 0;
   } else {
      de.conn = conn;

      while ((dp = mg_readdir(dirp)) != NULL) {
         /* Do not show current dir (but show hidden files as they will
          * also be removed) */
         if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, "..")) {
            continue;
         }

         mg_snprintf(
             conn, &truncated, path, sizeof(path), "%s/%s", dir, dp->d_name);

         /* If we don't memset stat structure to zero, mtime will have
          * garbage and strftime() will segfault later on in
          * print_dir_entry(). memset is required only if mg_stat()
          * fails. For more details, see
          * http://code.google.com/p/mongoose/issues/detail?id=79 */
         memset(&de.file, 0, sizeof(de.file));

         if (truncated) {
            /* Do not delete anything shorter */
            ok = 0;
            continue;
         }

         if (!mg_stat(conn, path, &de.file)) {
            mg_cry_internal(conn,
                            "%s: mg_stat(%s) failed: %s",
                            __func__,
                            path,
                            strerror(ERRNO));
            ok = 0;
         }

         if (de.file.is_directory) {
            if (remove_directory(conn, path) == 0) {
               ok = 0;
            }
         } else {
            /* This will fail file is the file is in memory */
            if (mg_remove(conn, path) == 0) {
               ok = 0;
            }
         }
      }
      (void)mg_closedir(dirp);

      IGNORE_UNUSED_RESULT(rmdir(dir));
   }

   return ok;
}
#endif


struct dir_scan_data {
   struct de *entries;
   unsigned int num_entries;
   unsigned int arr_size;
};


/* Behaves like realloc(), but frees original pointer on failure */
static void *
realloc2(void *ptr, size_t size)
{
   void *new_ptr = mg_realloc(ptr, size);
   if (new_ptr == NULL) {
      mg_free(ptr);
   }
   return new_ptr;
}


static int
dir_scan_callback(struct de *de, void *data)
{
   struct dir_scan_data *dsd = (struct dir_scan_data *)data;

   if ((dsd->entries == NULL) || (dsd->num_entries >= dsd->arr_size)) {
      dsd->arr_size *= 2;
      dsd->entries =
          (struct de *)realloc2(dsd->entries,
                                dsd->arr_size * sizeof(dsd->entries[0]));
   }
   if (dsd->entries == NULL) {
      /* TODO(lsm, low): propagate an error to the caller */
      dsd->num_entries = 0;
   } else {
      dsd->entries[dsd->num_entries].file_name = mg_strdup(de->file_name);
      dsd->entries[dsd->num_entries].file = de->file;
      dsd->entries[dsd->num_entries].conn = de->conn;
      dsd->num_entries++;
   }

   return 0;
}


static void
handle_directory_request(struct mg_connection *conn, const char *dir)
{
   unsigned int i;
   int sort_direction;
   struct dir_scan_data data = {NULL, 0, 128};
   char date[64];
   time_t curtime = time(NULL);

   if (!scan_directory(conn, dir, &data, dir_scan_callback)) {
      mg_send_http_error(conn,
                         500,
                         "Error: Cannot open directory\nopendir(%s): %s",
                         dir,
                         strerror(ERRNO));
      return;
   }

   gmt_time_string(date, sizeof(date), &curtime);

   if (!conn) {
      return;
   }

   sort_direction = ((conn->request_info.query_string != NULL)
                     && (conn->request_info.query_string[1] == 'd'))
                        ? 'a'
                        : 'd';

   conn->must_close = 1;
   mg_printf(conn, "HTTP/1.1 200 OK\r\n");
   send_static_cache_header(conn);
   send_additional_header(conn);
   mg_printf(conn,
             "Date: %s\r\n"
             "Connection: close\r\n"
             "Content-Type: text/html; charset=utf-8\r\n\r\n",
             date);
   mg_printf(conn,
             "<html><head><title>Index of %s</title>"
             "<style>th {text-align: left;}</style></head>"
             "<body><h1>Index of %s</h1><pre><table cellpadding=\"0\">"
             "<tr><th><a href=\"?n%c\">Name</a></th>"
             "<th><a href=\"?d%c\">Modified</a></th>"
             "<th><a href=\"?s%c\">Size</a></th></tr>"
             "<tr><td colspan=\"3\"><hr></td></tr>",
             conn->request_info.local_uri,
             conn->request_info.local_uri,
             sort_direction,
             sort_direction,
             sort_direction);

   /* Print first entry - link to a parent directory */
   mg_printf(conn,
             "<tr><td><a href=\"%s%s\">%s</a></td>"
             "<td>&nbsp;%s</td><td>&nbsp;&nbsp;%s</td></tr>\n",
             conn->request_info.local_uri,
             "..",
             "Parent directory",
             "-",
             "-");

   /* Sort and print directory entries */
   if (data.entries != NULL) {
      qsort(data.entries,
            (size_t)data.num_entries,
            sizeof(data.entries[0]),
            compare_dir_entries);
      for (i = 0; i < data.num_entries; i++) {
         print_dir_entry(&data.entries[i]);
         mg_free(data.entries[i].file_name);
      }
      mg_free(data.entries);
   }

   mg_printf(conn, "%s", "</table></body></html>");
   conn->status_code = 200;
}


/* Send len bytes from the opened file to the client. */
static void
send_file_data(struct mg_connection *conn,
               struct mg_file *filep,
               int64_t offset,
               int64_t len)
{
   char buf[MG_BUF_LEN];
   int to_read, num_read, num_written;
   int64_t size;

   if (!filep || !conn) {
      return;
   }

   /* Sanity check the offset */
   size = (filep->stat.size > INT64_MAX) ? INT64_MAX
                                         : (int64_t)(filep->stat.size);
   offset = (offset < 0) ? 0 : ((offset > size) ? size : offset);

#if defined(MG_USE_OPEN_FILE)
   if ((len > 0) && (filep->access.membuf != NULL) && (size > 0)) {
      /* file stored in memory */
      if (len > size - offset) {
         len = size - offset;
      }
      mg_write(conn, filep->access.membuf + offset, (size_t)len);
   } else /* else block below */
#endif
       if (len > 0 && filep->access.fp != NULL) {
/* file stored on disk */
#if defined(__linux__)
      /* sendfile is only available for Linux */
      if ((conn->ssl == 0) && (conn->throttle == 0)
          && (!mg_strcasecmp(conn->dom_ctx->config[ALLOW_SENDFILE_CALL],
                             "yes"))) {
         off_t sf_offs = (off_t)offset;
         ssize_t sf_sent;
         int sf_file = fileno(filep->access.fp);
         int loop_cnt = 0;

         do {
            /* 2147479552 (0x7FFFF000) is a limit found by experiment on
             * 64 bit Linux (2^31 minus one memory page of 4k?). */
            size_t sf_tosend =
                (size_t)((len < 0x7FFFF000) ? len : 0x7FFFF000);
            sf_sent =
                sendfile(conn->client.sock, sf_file, &sf_offs, sf_tosend);
            if (sf_sent > 0) {
               len -= sf_sent;
               offset += sf_sent;
            } else if (loop_cnt == 0) {
               /* This file can not be sent using sendfile.
                * This might be the case for pseudo-files in the
                * /sys/ and /proc/ file system.
                * Use the regular user mode copy code instead. */
               break;
            } else if (sf_sent == 0) {
               /* No error, but 0 bytes sent. May be EOF? */
               return;
            }
            loop_cnt++;

         } while ((len > 0) && (sf_sent >= 0));

         if (sf_sent > 0) {
            return; /* OK */
         }

         /* sf_sent<0 means error, thus fall back to the classic way */
         /* This is always the case, if sf_file is not a "normal" file,
          * e.g., for sending data from the output of a CGI process. */
         offset = (int64_t)sf_offs;
      }
#endif
      if ((offset > 0) && (fseeko(filep->access.fp, offset, SEEK_SET) != 0)) {
         mg_cry_internal(conn,
                         "%s: fseeko() failed: %s",
                         __func__,
                         strerror(ERRNO));
         mg_send_http_error(
             conn,
             500,
             "%s",
             "Error: Unable to access file at requested position.");
      } else {
         while (len > 0) {
            /* Calculate how much to read from the file in the buffer */
            to_read = sizeof(buf);
            if ((int64_t)to_read > len) {
               to_read = (int)len;
            }

            /* Read from file, exit the loop on error */
            if ((num_read =
                     (int)fread(buf, 1, (size_t)to_read, filep->access.fp))
                <= 0) {
               break;
            }

            /* Send read bytes to the client, exit the loop on error */
            if ((num_written = mg_write(conn, buf, (size_t)num_read))
                != num_read) {
               break;
            }

            /* Both read and were successful, adjust counters */
            len -= num_written;
         }
      }
   }
}


static int
parse_range_header(const char *header, int64_t *a, int64_t *b)
{
   return sscanf(header, "bytes=%" INT64_FMT "-%" INT64_FMT, a, b);
}


static void
construct_etag(char *buf, size_t buf_len, const struct mg_file_stat *filestat)
{
   if ((filestat != NULL) && (buf != NULL)) {
      mg_snprintf(NULL,
                  NULL, /* All calls to construct_etag use 64 byte buffer */
                  buf,
                  buf_len,
                  "\"%lx.%" INT64_FMT "\"",
                  (unsigned long)filestat->last_modified,
                  filestat->size);
   }
}


static void
fclose_on_exec(struct mg_file_access *filep, struct mg_connection *conn)
{
   if (filep != NULL && filep->fp != NULL) {
#if defined(_WIN32)
      (void)conn; /* Unused. */
#else
      if (fcntl(fileno(filep->fp), F_SETFD, FD_CLOEXEC) != 0) {
         mg_cry_internal(conn,
                         "%s: fcntl(F_SETFD FD_CLOEXEC) failed: %s",
                         __func__,
                         strerror(ERRNO));
      }
#endif
   }
}


#if defined(USE_ZLIB)
#include "mod_zlib.inl"
#endif


static void
handle_static_file_request(struct mg_connection *conn,
                           const char *path,
                           struct mg_file *filep,
                           const char *mime_type,
                           const char *additional_headers)
{
   char date[64], lm[64], etag[64];
   char range[128]; /* large enough, so there will be no overflow */
   const char *msg = "OK", *hdr;
   time_t curtime = time(NULL);
   int64_t cl, r1, r2;
   struct vec mime_vec;
   int n, truncated;
   char gz_path[PATH_MAX];
   const char *encoding = "";
   const char *cors1, *cors2, *cors3;
   int is_head_request;

#if defined(USE_ZLIB)
   /* Compression is allowed, unless there is a reason not to use compression.
    * If the file is already compressed, too small or a "range" request was
    * made, on the fly compression is not possible. */
   int allow_on_the_fly_compression = 1;
#endif

   if ((conn == NULL) || (conn->dom_ctx == NULL) || (filep == NULL)) {
      return;
   }

   is_head_request = !strcmp(conn->request_info.request_method, "HEAD");

   if (mime_type == NULL) {
      get_mime_type(conn, path, &mime_vec);
   } else {
      mime_vec.ptr = mime_type;
      mime_vec.len = strlen(mime_type);
   }
   if (filep->stat.size > INT64_MAX) {
      mg_send_http_error(conn,
                         500,
                         "Error: File size is too large to send\n%" INT64_FMT,
                         filep->stat.size);
      return;
   }
   cl = (int64_t)filep->stat.size;
   conn->status_code = 200;
   range[0] = '\0';

#if defined(USE_ZLIB)
   /* if this file is in fact a pre-gzipped file, rewrite its filename
    * it's important to rewrite the filename after resolving
    * the mime type from it, to preserve the actual file's type */
   if (!conn->accept_gzip) {
      allow_on_the_fly_compression = 0;
   }
#endif

   if (filep->stat.is_gzipped) {
      mg_snprintf(conn, &truncated, gz_path, sizeof(gz_path), "%s.gz", path);

      if (truncated) {
         mg_send_http_error(conn,
                            500,
                            "Error: Path of zipped file too long (%s)",
                            path);
         return;
      }

      path = gz_path;
      encoding = "Content-Encoding: gzip\r\n";

#if defined(USE_ZLIB)
      /* File is already compressed. No "on the fly" compression. */
      allow_on_the_fly_compression = 0;
#endif
   }

   if (!mg_fopen(conn, path, MG_FOPEN_MODE_READ, filep)) {
      mg_send_http_error(conn,
                         500,
                         "Error: Cannot open file\nfopen(%s): %s",
                         path,
                         strerror(ERRNO));
      return;
   }

   fclose_on_exec(&filep->access, conn);

   /* If "Range" request was made: parse header, send only selected part
    * of the file. */
   r1 = r2 = 0;
   hdr = mg_get_header(conn, "Range");
   if ((hdr != NULL) && ((n = parse_range_header(hdr, &r1, &r2)) > 0)
       && (r1 >= 0) && (r2 >= 0)) {
      /* actually, range requests don't play well with a pre-gzipped
       * file (since the range is specified in the uncompressed space) */
      if (filep->stat.is_gzipped) {
         mg_send_http_error(
             conn,
             416, /* 416 = Range Not Satisfiable */
             "%s",
             "Error: Range requests in gzipped files are not supported");
         (void)mg_fclose(
             &filep->access); /* ignore error on read only file */
         return;
      }
      conn->status_code = 206;
      cl = (n == 2) ? (((r2 > cl) ? cl : r2) - r1 + 1) : (cl - r1);
      mg_snprintf(conn,
                  NULL, /* range buffer is big enough */
                  range,
                  sizeof(range),
                  "Content-Range: bytes "
                  "%" INT64_FMT "-%" INT64_FMT "/%" INT64_FMT "\r\n",
                  r1,
                  r1 + cl - 1,
                  filep->stat.size);
      msg = "Partial Content";

#if defined(USE_ZLIB)
      /* Do not compress ranges. */
      allow_on_the_fly_compression = 0;
#endif
   }

/* Do not compress small files. Small files do not benefit from file
 * compression, but there is still some overhead. */
#if defined(USE_ZLIB)
   if (filep->stat.size < MG_FILE_COMPRESSION_SIZE_LIMIT) {
      /* File is below the size limit. */
      allow_on_the_fly_compression = 0;
   }
#endif

   /* Standard CORS header */
   hdr = mg_get_header(conn, "Origin");
   if (hdr) {
      /* Cross-origin resource sharing (CORS), see
       * http://www.html5rocks.com/en/tutorials/cors/,
       * http://www.html5rocks.com/static/images/cors_server_flowchart.png
       * -
       * preflight is not supported for files. */
      cors1 = "Access-Control-Allow-Origin: ";
      cors2 = conn->dom_ctx->config[ACCESS_CONTROL_ALLOW_ORIGIN];
      cors3 = "\r\n";
   } else {
      cors1 = cors2 = cors3 = "";
   }

   /* Prepare Etag, Date, Last-Modified headers. Must be in UTC,
    * according to
    * http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3 */
   gmt_time_string(date, sizeof(date), &curtime);
   gmt_time_string(lm, sizeof(lm), &filep->stat.last_modified);
   construct_etag(etag, sizeof(etag), &filep->stat);

   /* Send header */
   (void)mg_printf(conn,
                   "HTTP/1.1 %d %s\r\n"
                   "%s%s%s" /* CORS */
                   "Date: %s\r\n"
                   "Last-Modified: %s\r\n"
                   "Etag: %s\r\n"
                   "Content-Type: %.*s\r\n"
                   "Connection: %s\r\n",
                   conn->status_code,
                   msg,
                   cors1,
                   cors2,
                   cors3,
                   date,
                   lm,
                   etag,
                   (int)mime_vec.len,
                   mime_vec.ptr,
                   suggest_connection_header(conn));
   send_static_cache_header(conn);
   send_additional_header(conn);

#if defined(USE_ZLIB)
   /* On the fly compression allowed */
   if (allow_on_the_fly_compression) {
      /* For on the fly compression, we don't know the content size in
       * advance, so we have to use chunked encoding */
      (void)mg_printf(conn,
                      "Content-Encoding: gzip\r\n"
                      "Transfer-Encoding: chunked\r\n");
   } else
#endif
   {
      /* Without on-the-fly compression, we know the content-length
       * and we can use ranges (with on-the-fly compression we cannot).
       * So we send these response headers only in this case. */
      (void)mg_printf(conn,
                      "Content-Length: %" INT64_FMT "\r\n"
                      "Accept-Ranges: bytes\r\n"
                      "%s" /* range */
                      "%s" /* encoding */,
                      cl,
                      range,
                      encoding);
   }

   /* The previous code must not add any header starting with X- to make
    * sure no one of the additional_headers is included twice */
   if (additional_headers != NULL) {
      (void)mg_printf(conn,
                      "%.*s\r\n\r\n",
                      (int)strlen(additional_headers),
                      additional_headers);
   } else {
      (void)mg_printf(conn, "\r\n");
   }

   if (!is_head_request) {
#if defined(USE_ZLIB)
      if (allow_on_the_fly_compression) {
         /* Compress and send */
         send_compressed_data(conn, filep);
      } else
#endif
      {
         /* Send file directly */
         send_file_data(conn, filep, r1, cl);
      }
   }
   (void)mg_fclose(&filep->access); /* ignore error on read only file */
}


int
mg_send_file_body(struct mg_connection *conn, const char *path)
{
   struct mg_file file = STRUCT_FILE_INITIALIZER;
   if (!mg_fopen(conn, path, MG_FOPEN_MODE_READ, &file)) {
      return -1;
   }
   fclose_on_exec(&file.access, conn);
   send_file_data(conn, &file, 0, INT64_MAX);
   (void)mg_fclose(&file.access); /* Ignore errors for readonly files */
   return 0;                      /* >= 0 for OK */
}


#if !defined(NO_CACHING)
/* Return True if we should reply 304 Not Modified. */
static int
is_not_modified(const struct mg_connection *conn,
                const struct mg_file_stat *filestat)
{
   char etag[64];
   const char *ims = mg_get_header(conn, "If-Modified-Since");
   const char *inm = mg_get_header(conn, "If-None-Match");
   construct_etag(etag, sizeof(etag), filestat);

   return ((inm != NULL) && !mg_strcasecmp(etag, inm))
          || ((ims != NULL)
              && (filestat->last_modified <= parse_date_string(ims)));
}

static void
handle_not_modified_static_file_request(struct mg_connection *conn,
                                        struct mg_file *filep)
{
   char date[64], lm[64], etag[64];
   time_t curtime = time(NULL);

   if ((conn == NULL) || (filep == NULL)) {
      return;
   }
   conn->status_code = 304;
   gmt_time_string(date, sizeof(date), &curtime);
   gmt_time_string(lm, sizeof(lm), &filep->stat.last_modified);
   construct_etag(etag, sizeof(etag), &filep->stat);

   (void)mg_printf(conn,
                   "HTTP/1.1 %d %s\r\n"
                   "Date: %s\r\n",
                   conn->status_code,
                   mg_get_response_code_text(conn, conn->status_code),
                   date);
   send_static_cache_header(conn);
   send_additional_header(conn);
   (void)mg_printf(conn,
                   "Last-Modified: %s\r\n"
                   "Etag: %s\r\n"
                   "Connection: %s\r\n"
                   "\r\n",
                   lm,
                   etag,
                   suggest_connection_header(conn));
}
#endif


void
mg_send_file(struct mg_connection *conn, const char *path)
{
   mg_send_mime_file2(conn, path, NULL, NULL);
}


void
mg_send_mime_file(struct mg_connection *conn,
                  const char *path,
                  const char *mime_type)
{
   mg_send_mime_file2(conn, path, mime_type, NULL);
}


void
mg_send_mime_file2(struct mg_connection *conn,
                   const char *path,
                   const char *mime_type,
                   const char *additional_headers)
{
   struct mg_file file = STRUCT_FILE_INITIALIZER;

   if (!conn) {
      /* No conn */
      return;
   }

   if (mg_stat(conn, path, &file.stat)) {
#if !defined(NO_CACHING)
      if (is_not_modified(conn, &file.stat)) {
         /* Send 304 "Not Modified" - this must not send any body data */
         handle_not_modified_static_file_request(conn, &file);
      } else
#endif /* NO_CACHING */
          if (file.stat.is_directory) {
         if (!mg_strcasecmp(conn->dom_ctx->config[ENABLE_DIRECTORY_LISTING],
                            "yes")) {
            handle_directory_request(conn, path);
         } else {
            mg_send_http_error(conn,
                               403,
                               "%s",
                               "Error: Directory listing denied");
         }
      } else {
         handle_static_file_request(
             conn, path, &file, mime_type, additional_headers);
      }
   } else {
      mg_send_http_error(conn, 404, "%s", "Error: File not found");
   }
}


/* For a given PUT path, create all intermediate subdirectories.
 * Return  0  if the path itself is a directory.
 * Return  1  if the path leads to a file.
 * Return -1  for if the path is too long.
 * Return -2  if path can not be created.
 */
static int
put_dir(struct mg_connection *conn, const char *path)
{
   char buf[PATH_MAX];
   const char *s, *p;
   struct mg_file file = STRUCT_FILE_INITIALIZER;
   size_t len;
   int res = 1;

   for (s = p = path + 2; (p = strchr(s, '/')) != NULL; s = ++p) {
      len = (size_t)(p - path);
      if (len >= sizeof(buf)) {
         /* path too long */
         res = -1;
         break;
      }
      memcpy(buf, path, len);
      buf[len] = '\0';

      /* Try to create intermediate directory */
      DEBUG_TRACE("mkdir(%s)", buf);
      if (!mg_stat(conn, buf, &file.stat) && mg_mkdir(conn, buf, 0755) != 0) {
         /* path does not exixt and can not be created */
         res = -2;
         break;
      }

      /* Is path itself a directory? */
      if (p[1] == '\0') {
         res = 0;
      }
   }

   return res;
}


static void
remove_bad_file(const struct mg_connection *conn, const char *path)
{
   int r = mg_remove(conn, path);
   if (r != 0) {
      mg_cry_internal(conn,
                      "%s: Cannot remove invalid file %s",
                      __func__,
                      path);
   }
}


long long
mg_store_body(struct mg_connection *conn, const char *path)
{
   char buf[MG_BUF_LEN];
   long long len = 0;
   int ret, n;
   struct mg_file fi;

   if (conn->consumed_content != 0) {
      mg_cry_internal(conn, "%s: Contents already consumed", __func__);
      return -11;
   }

   ret = put_dir(conn, path);
   if (ret < 0) {
      /* -1 for path too long,
       * -2 for path can not be created. */
      return ret;
   }
   if (ret != 1) {
      /* Return 0 means, path itself is a directory. */
      return 0;
   }

   if (mg_fopen(conn, path, MG_FOPEN_MODE_WRITE, &fi) == 0) {
      return -12;
   }

   ret = mg_read(conn, buf, sizeof(buf));
   while (ret > 0) {
      n = (int)fwrite(buf, 1, (size_t)ret, fi.access.fp);
      if (n != ret) {
         (void)mg_fclose(
             &fi.access); /* File is bad and will be removed anyway. */
         remove_bad_file(conn, path);
         return -13;
      }
      len += ret;
      ret = mg_read(conn, buf, sizeof(buf));
   }

   /* File is open for writing. If fclose fails, there was probably an
    * error flushing the buffer to disk, so the file on disk might be
    * broken. Delete it and return an error to the caller. */
   if (mg_fclose(&fi.access) != 0) {
      remove_bad_file(conn, path);
      return -14;
   }

   return len;
}


/* Parse a buffer:
 * Forward the string pointer till the end of a word, then
 * terminate it and forward till the begin of the next word.
 */
static int
skip_to_end_of_word_and_terminate(char **ppw, int eol)
{
   /* Forward until a space is found - use isgraph here */
   /* See http://www.cplusplus.com/reference/cctype/ */
   while (isgraph(**ppw)) {
      (*ppw)++;
   }

   /* Check end of word */
   if (eol) {
      /* must be a end of line */
      if ((**ppw != '\r') && (**ppw != '\n')) {
         return -1;
      }
   } else {
      /* must be a end of a word, but not a line */
      if (**ppw != ' ') {
         return -1;
      }
   }

   /* Terminate and forward to the next word */
   do {
      **ppw = 0;
      (*ppw)++;
   } while ((**ppw) && isspace(**ppw));

   /* Check after term */
   if (!eol) {
      /* if it's not the end of line, there must be a next word */
      if (!isgraph(**ppw)) {
         return -1;
      }
   }

   /* ok */
   return 1;
}


/* Parse HTTP headers from the given buffer, advance buf pointer
 * to the point where parsing stopped.
 * All parameters must be valid pointers (not NULL).
 * Return <0 on error. */
static int
parse_http_headers(char **buf, struct mg_header hdr[MG_MAX_HEADERS])
{
   int i;
   int num_headers = 0;

   for (i = 0; i < (int)MG_MAX_HEADERS; i++) {
      char *dp = *buf;
      while ((*dp != ':') && (*dp >= 33) && (*dp <= 126)) {
         dp++;
      }
      if (dp == *buf) {
         /* End of headers reached. */
         break;
      }
      if (*dp != ':') {
         /* This is not a valid field. */
         return -1;
      }

      /* End of header key (*dp == ':') */
      /* Truncate here and set the key name */
      *dp = 0;
      hdr[i].name = *buf;
      do {
         dp++;
      } while (*dp == ' ');

      /* The rest of the line is the value */
      hdr[i].value = dp;
      *buf = dp + strcspn(dp, "\r\n");
      if (((*buf)[0] != '\r') || ((*buf)[1] != '\n')) {
         *buf = NULL;
      }

      num_headers = i + 1;
      if (*buf) {
         (*buf)[0] = 0;
         (*buf)[1] = 0;
         *buf += 2;
      } else {
         *buf = dp;
         break;
      }

      if ((*buf)[0] == '\r') {
         /* This is the end of the header */
         break;
      }
   }
   return num_headers;
}


struct mg_http_method_info {
   const char *name;
   int request_has_body;
   int response_has_body;
   int is_safe;
   int is_idempotent;
   int is_cacheable;
};


/* https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods */
static struct mg_http_method_info http_methods[] = {
    /* HTTP (RFC 2616) */
    {"GET", 0, 1, 1, 1, 1},
    {"POST", 1, 1, 0, 0, 0},
    {"PUT", 1, 0, 0, 1, 0},
    {"DELETE", 0, 0, 0, 1, 0},
    {"HEAD", 0, 0, 1, 1, 1},
    {"OPTIONS", 0, 0, 1, 1, 0},
    {"CONNECT", 1, 1, 0, 0, 0},
    /* TRACE method (RFC 2616) is not supported for security reasons */

    /* PATCH method (RFC 5789) */
    {"PATCH", 1, 0, 0, 0, 0},
    /* PATCH method only allowed for CGI/Lua/LSP and callbacks. */

    /* WEBDAV (RFC 2518) */
    {"PROPFIND", 0, 1, 1, 1, 0},
    /* http://www.webdav.org/specs/rfc4918.html, 9.1:
     * Some PROPFIND results MAY be cached, with care,
     * as there is no cache validation mechanism for
     * most properties. This method is both safe and
     * idempotent (see Section 9.1 of [RFC2616]). */
    {"MKCOL", 0, 0, 0, 1, 0},
    /* http://www.webdav.org/specs/rfc4918.html, 9.1:
     * When MKCOL is invoked without a request body,
     * the newly created collection SHOULD have no
     * members. A MKCOL request message may contain
     * a message body. The precise behavior of a MKCOL
     * request when the body is present is undefined,
     * ... ==> We do not support MKCOL with body data.
     * This method is idempotent, but not safe (see
     * Section 9.1 of [RFC2616]). Responses to this
     * method MUST NOT be cached. */

    /* Unsupported WEBDAV Methods: */
    /* PROPPATCH, COPY, MOVE, LOCK, UNLOCK (RFC 2518) */
    /* + 11 methods from RFC 3253 */
    /* ORDERPATCH (RFC 3648) */
    /* ACL (RFC 3744) */
    /* SEARCH (RFC 5323) */
    /* + MicroSoft extensions
     * https://msdn.microsoft.com/en-us/library/aa142917.aspx */

    /* REPORT method (RFC 3253) */
    {"REPORT", 1, 1, 1, 1, 1},
    /* REPORT method only allowed for CGI/Lua/LSP and callbacks. */
    /* It was defined for WEBDAV in RFC 3253, Sec. 3.6
     * (https://tools.ietf.org/html/rfc3253#section-3.6), but seems
     * to be useful for REST in case a "GET request with body" is
     * required. */

    {NULL, 0, 0, 0, 0, 0}
    /* end of list */
};


static const struct mg_http_method_info *
get_http_method_info(const char *method)
{
   /* Check if the method is known to the server. The list of all known
    * HTTP methods can be found here at
    * http://www.iana.org/assignments/http-methods/http-methods.xhtml
    */
   const struct mg_http_method_info *m = http_methods;

   while (m->name) {
      if (!strcmp(m->name, method)) {
         return m;
      }
      m++;
   }
   return NULL;
}


static int
is_valid_http_method(const char *method)
{
   return (get_http_method_info(method) != NULL);
}


/* Parse HTTP request, fill in mg_request_info structure.
 * This function modifies the buffer by NUL-terminating
 * HTTP request components, header names and header values.
 * Parameters:
 *   buf (in/out): pointer to the HTTP header to parse and split
 *   len (in): length of HTTP header buffer
 *   re (out): parsed header as mg_request_info
 * buf and ri must be valid pointers (not NULL), len>0.
 * Returns <0 on error. */
static int
parse_http_request(char *buf, int len, struct mg_request_info *ri)
{
   int request_length;
   int init_skip = 0;

   /* Reset attributes. DO NOT TOUCH is_ssl, remote_addr,
    * remote_port */
   ri->remote_user = ri->request_method = ri->request_uri = ri->http_version =
       NULL;
   ri->num_headers = 0;

   /* RFC says that all initial whitespaces should be ingored */
   /* This included all leading \r and \n (isspace) */
   /* See table: http://www.cplusplus.com/reference/cctype/ */
   while ((len > 0) && isspace(*(unsigned char *)buf)) {
      buf++;
      len--;
      init_skip++;
   }

   if (len == 0) {
      /* Incomplete request */
      return 0;
   }

   /* Control characters are not allowed, including zero */
   if (iscntrl(*(unsigned char *)buf)) {
      return -1;
   }

   /* Find end of HTTP header */
   request_length = get_http_header_len(buf, len);
   if (request_length <= 0) {
      return request_length;
   }
   buf[request_length - 1] = '\0';

   if ((*buf == 0) || (*buf == '\r') || (*buf == '\n')) {
      return -1;
   }

   /* The first word has to be the HTTP method */
   ri->request_method = buf;

   if (skip_to_end_of_word_and_terminate(&buf, 0) <= 0) {
      return -1;
   }

   /* Check for a valid http method */
   if (!is_valid_http_method(ri->request_method)) {
      return -1;
   }

   /* The second word is the URI */
   ri->request_uri = buf;

   if (skip_to_end_of_word_and_terminate(&buf, 0) <= 0) {
      return -1;
   }

   /* Next would be the HTTP version */
   ri->http_version = buf;

   if (skip_to_end_of_word_and_terminate(&buf, 1) <= 0) {
      return -1;
   }

   /* Check for a valid HTTP version key */
   if (strncmp(ri->http_version, "HTTP/", 5) != 0) {
      /* Invalid request */
      return -1;
   }
   ri->http_version += 5;


   /* Parse all HTTP headers */
   ri->num_headers = parse_http_headers(&buf, ri->http_headers);
   if (ri->num_headers < 0) {
      /* Error while parsing headers */
      return -1;
   }

   return request_length + init_skip;
}


static int
parse_http_response(char *buf, int len, struct mg_response_info *ri)
{
   int response_length;
   int init_skip = 0;
   char *tmp, *tmp2;
   long l;

   /* Initialize elements. */
   ri->http_version = ri->status_text = NULL;
   ri->num_headers = ri->status_code = 0;

   /* RFC says that all initial whitespaces should be ingored */
   /* This included all leading \r and \n (isspace) */
   /* See table: http://www.cplusplus.com/reference/cctype/ */
   while ((len > 0) && isspace(*(unsigned char *)buf)) {
      buf++;
      len--;
      init_skip++;
   }

   if (len == 0) {
      /* Incomplete request */
      return 0;
   }

   /* Control characters are not allowed, including zero */
   if (iscntrl(*(unsigned char *)buf)) {
      return -1;
   }

   /* Find end of HTTP header */
   response_length = get_http_header_len(buf, len);
   if (response_length <= 0) {
      return response_length;
   }
   buf[response_length - 1] = '\0';

   if ((*buf == 0) || (*buf == '\r') || (*buf == '\n')) {
      return -1;
   }

   /* The first word is the HTTP version */
   /* Check for a valid HTTP version key */
   if (strncmp(buf, "HTTP/", 5) != 0) {
      /* Invalid request */
      return -1;
   }
   buf += 5;
   if (!isgraph(buf[0])) {
      /* Invalid request */
      return -1;
   }
   ri->http_version = buf;

   if (skip_to_end_of_word_and_terminate(&buf, 0) <= 0) {
      return -1;
   }

   /* The second word is the status as a number */
   tmp = buf;

   if (skip_to_end_of_word_and_terminate(&buf, 0) <= 0) {
      return -1;
   }

   l = strtol(tmp, &tmp2, 10);
   if ((l < 100) || (l >= 1000) || ((tmp2 - tmp) != 3) || (*tmp2 != 0)) {
      /* Everything else but a 3 digit code is invalid */
      return -1;
   }
   ri->status_code = (int)l;

   /* The rest of the line is the status text */
   ri->status_text = buf;

   /* Find end of status text */
   /* isgraph or isspace = isprint */
   while (isprint(*buf)) {
      buf++;
   }
   if ((*buf != '\r') && (*buf != '\n')) {
      return -1;
   }
   /* Terminate string and forward buf to next line */
   do {
      *buf = 0;
      buf++;
   } while ((*buf) && isspace(*buf));


   /* Parse all HTTP headers */
   ri->num_headers = parse_http_headers(&buf, ri->http_headers);
   if (ri->num_headers < 0) {
      /* Error while parsing headers */
      return -1;
   }

   return response_length + init_skip;
}


/* Keep reading the input (either opened file descriptor fd, or socket sock,
 * or SSL descriptor ssl) into buffer buf, until \r\n\r\n appears in the
 * buffer (which marks the end of HTTP request). Buffer buf may already
 * have some data. The length of the data is stored in nread.
 * Upon every read operation, increase nread by the number of bytes read. */
static int
read_message(FILE *fp,
             struct mg_connection *conn,
             char *buf,
             int bufsiz,
             int *nread)
{
   int request_len, n = 0;
   struct timespec last_action_time;
   double request_timeout;

   if (!conn) {
      return 0;
   }

   memset(&last_action_time, 0, sizeof(last_action_time));

   if (conn->dom_ctx->config[REQUEST_TIMEOUT]) {
      /* value of request_timeout is in seconds, config in milliseconds */
      request_timeout = atof(conn->dom_ctx->config[REQUEST_TIMEOUT]) / 1000.0;
   } else {
      request_timeout = -1.0;
   }
   if (conn->handled_requests > 0) {
      if (conn->dom_ctx->config[KEEP_ALIVE_TIMEOUT]) {
         request_timeout =
             atof(conn->dom_ctx->config[KEEP_ALIVE_TIMEOUT]) / 1000.0;
      }
   }

   request_len = get_http_header_len(buf, *nread);

   /* first time reading from this connection */
   clock_gettime(CLOCK_MONOTONIC, &last_action_time);

   while (request_len == 0) {
      /* Full request not yet received */
      if (conn->phys_ctx->stop_flag != 0) {
         /* Server is to be stopped. */
         return -1;
      }

      if (*nread >= bufsiz) {
         /* Request too long */
         return -2;
      }

      n = pull_inner(
          fp, conn, buf + *nread, bufsiz - *nread, request_timeout);
      if (n == -2) {
         /* Receive error */
         return -1;
      }
      if (n > 0) {
         *nread += n;
         request_len = get_http_header_len(buf, *nread);
      } else {
         request_len = 0;
      }

      if ((request_len == 0) && (request_timeout >= 0)) {
         if (mg_difftimespec(&last_action_time, &(conn->req_time))
             > request_timeout) {
            /* Timeout */
            return -1;
         }
         clock_gettime(CLOCK_MONOTONIC, &last_action_time);
      }
   }

   return request_len;
}


#if !defined(NO_CGI) || !defined(NO_FILES)
static int
forward_body_data(struct mg_connection *conn, FILE *fp, SOCKET sock, SSL *ssl)
{
   const char *expect, *body;
   char buf[MG_BUF_LEN];
   int to_read, nread, success = 0;
   int64_t buffered_len;
   double timeout = -1.0;

   if (!conn) {
      return 0;
   }
   if (conn->dom_ctx->config[REQUEST_TIMEOUT]) {
      timeout = atoi(conn->dom_ctx->config[REQUEST_TIMEOUT]) / 1000.0;
   }

   expect = mg_get_header(conn, "Expect");
   DEBUG_ASSERT(fp != NULL);
   if (!fp) {
      mg_send_http_error(conn, 500, "%s", "Error: NULL File");
      return 0;
   }

   if ((conn->content_len == -1) && (!conn->is_chunked)) {
      /* Content length is not specified by the client. */
      mg_send_http_error(conn,
                         411,
                         "%s",
                         "Error: Client did not specify content length");
   } else if ((expect != NULL)
              && (mg_strcasecmp(expect, "100-continue") != 0)) {
      /* Client sent an "Expect: xyz" header and xyz is not 100-continue.
       */
      mg_send_http_error(conn,
                         417,
                         "Error: Can not fulfill expectation %s",
                         expect);
   } else {
      if (expect != NULL) {
         (void)mg_printf(conn, "%s", "HTTP/1.1 100 Continue\r\n\r\n");
         conn->status_code = 100;
      } else {
         conn->status_code = 200;
      }

      buffered_len = (int64_t)(conn->data_len) - (int64_t)conn->request_len
                     - conn->consumed_content;

      DEBUG_ASSERT(buffered_len >= 0);
      DEBUG_ASSERT(conn->consumed_content == 0);

      if ((buffered_len < 0) || (conn->consumed_content != 0)) {
         mg_send_http_error(conn, 500, "%s", "Error: Size mismatch");
         return 0;
      }

      if (buffered_len > 0) {
         if ((int64_t)buffered_len > conn->content_len) {
            buffered_len = (int)conn->content_len;
         }
         body = conn->buf + conn->request_len + conn->consumed_content;
         push_all(
             conn->phys_ctx, fp, sock, ssl, body, (int64_t)buffered_len);
         conn->consumed_content += buffered_len;
      }

      nread = 0;
      while (conn->consumed_content < conn->content_len) {
         to_read = sizeof(buf);
         if ((int64_t)to_read > conn->content_len - conn->consumed_content) {
            to_read = (int)(conn->content_len - conn->consumed_content);
         }
         nread = pull_inner(NULL, conn, buf, to_read, timeout);
         if (nread == -2) {
            /* error */
            break;
         }
         if (nread > 0) {
            if (push_all(conn->phys_ctx, fp, sock, ssl, buf, nread)
                != nread) {
               break;
            }
         }
         conn->consumed_content += nread;
      }

      if (conn->consumed_content == conn->content_len) {
         success = (nread >= 0);
      }

      /* Each error code path in this function must send an error */
      if (!success) {
         /* NOTE: Maybe some data has already been sent. */
         /* TODO (low): If some data has been sent, a correct error
          * reply can no longer be sent, so just close the connection */
         mg_send_http_error(conn, 500, "%s", "");
      }
   }

   return success;
}
#endif


#if defined(USE_TIMERS)

#define TIMER_API static
#include "timer.inl"

#endif /* USE_TIMERS */


#if !defined(NO_CGI)
/* This structure helps to create an environment for the spawned CGI
 * program.
 * Environment is an array of "VARIABLE=VALUE\0" ASCIIZ strings,
 * last element must be NULL.
 * However, on Windows there is a requirement that all these
 * VARIABLE=VALUE\0
 * strings must reside in a contiguous buffer. The end of the buffer is
 * marked by two '\0' characters.
 * We satisfy both worlds: we create an envp array (which is vars), all
 * entries are actually pointers inside buf. */
struct cgi_environment {
   struct mg_connection *conn;
   /* Data block */
   char *buf;      /* Environment buffer */
   size_t buflen;  /* Space available in buf */
   size_t bufused; /* Space taken in buf */
                   /* Index block */
   char **var;     /* char **envp */
   size_t varlen;  /* Number of variables available in var */
   size_t varused; /* Number of variables stored in var */
};


static void addenv(struct cgi_environment *env,
                   PRINTF_FORMAT_STRING(const char *fmt),
                   ...) PRINTF_ARGS(2, 3);

/* Append VARIABLE=VALUE\0 string to the buffer, and add a respective
 * pointer into the vars array. Assumes env != NULL and fmt != NULL. */
static void
addenv(struct cgi_environment *env, const char *fmt, ...)
{
   size_t n, space;
   int truncated = 0;
   char *added;
   va_list ap;

   /* Calculate how much space is left in the buffer */
   space = (env->buflen - env->bufused);

   /* Calculate an estimate for the required space */
   n = strlen(fmt) + 2 + 128;

   do {
      if (space <= n) {
         /* Allocate new buffer */
         n = env->buflen + CGI_ENVIRONMENT_SIZE;
         added = (char *)mg_realloc_ctx(env->buf, n, env->conn->phys_ctx);
         if (!added) {
            /* Out of memory */
            mg_cry_internal(
                env->conn,
                "%s: Cannot allocate memory for CGI variable [%s]",
                __func__,
                fmt);
            return;
         }
         env->buf = added;
         env->buflen = n;
         space = (env->buflen - env->bufused);
      }

      /* Make a pointer to the free space int the buffer */
      added = env->buf + env->bufused;

      /* Copy VARIABLE=VALUE\0 string into the free space */
      va_start(ap, fmt);
      mg_vsnprintf(env->conn, &truncated, added, (size_t)space, fmt, ap);
      va_end(ap);

      /* Do not add truncated strings to the environment */
      if (truncated) {
         /* Reallocate the buffer */
         space = 0;
         n = 1;
      }
   } while (truncated);

   /* Calculate number of bytes added to the environment */
   n = strlen(added) + 1;
   env->bufused += n;

   /* Now update the variable index */
   space = (env->varlen - env->varused);
   if (space < 2) {
      mg_cry_internal(env->conn,
                      "%s: Cannot register CGI variable [%s]",
                      __func__,
                      fmt);
      return;
   }

   /* Append a pointer to the added string into the envp array */
   env->var[env->varused] = added;
   env->varused++;
}

/* Return 0 on success, non-zero if an error occurs. */

static int
prepare_cgi_environment(struct mg_connection *conn,
                        const char *prog,
                        struct cgi_environment *env)
{
   const char *s;
   struct vec var_vec;
   char *p, src_addr[IP_ADDR_STR_LEN], http_var_name[128];
   int i, truncated, uri_len;

   if ((conn == NULL) || (prog == NULL) || (env == NULL)) {
      return -1;
   }

   env->conn = conn;
   env->buflen = CGI_ENVIRONMENT_SIZE;
   env->bufused = 0;
   env->buf = (char *)mg_malloc_ctx(env->buflen, conn->phys_ctx);
   if (env->buf == NULL) {
      mg_cry_internal(conn,
                      "%s: Not enough memory for environmental buffer",
                      __func__);
      return -1;
   }
   env->varlen = MAX_CGI_ENVIR_VARS;
   env->varused = 0;
   env->var =
       (char **)mg_malloc_ctx(env->buflen * sizeof(char *), conn->phys_ctx);
   if (env->var == NULL) {
      mg_cry_internal(conn,
                      "%s: Not enough memory for environmental variables",
                      __func__);
      mg_free(env->buf);
      return -1;
   }

   addenv(env, "SERVER_NAME=%s", conn->dom_ctx->config[AUTHENTICATION_DOMAIN]);
   addenv(env, "SERVER_ROOT=%s", conn->dom_ctx->config[DOCUMENT_ROOT]);
   addenv(env, "DOCUMENT_ROOT=%s", conn->dom_ctx->config[DOCUMENT_ROOT]);
   addenv(env, "SERVER_SOFTWARE=CivetWeb/%s", mg_version());

   /* Prepare the environment block */
   addenv(env, "%s", "GATEWAY_INTERFACE=CGI/1.1");
   addenv(env, "%s", "SERVER_PROTOCOL=HTTP/1.1");
   addenv(env, "%s", "REDIRECT_STATUS=200"); /* For PHP */

#if defined(USE_IPV6)
   if (conn->client.lsa.sa.sa_family == AF_INET6) {
      addenv(env, "SERVER_PORT=%d", ntohs(conn->client.lsa.sin6.sin6_port));
   } else
#endif
   {
      addenv(env, "SERVER_PORT=%d", ntohs(conn->client.lsa.sin.sin_port));
   }

   sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);
   addenv(env, "REMOTE_ADDR=%s", src_addr);

   addenv(env, "REQUEST_METHOD=%s", conn->request_info.request_method);
   addenv(env, "REMOTE_PORT=%d", conn->request_info.remote_port);

   addenv(env, "REQUEST_URI=%s", conn->request_info.request_uri);
   addenv(env, "LOCAL_URI=%s", conn->request_info.local_uri);

   /* SCRIPT_NAME */
   uri_len = (int)strlen(conn->request_info.local_uri);
   if (conn->path_info == NULL) {
      if (conn->request_info.local_uri[uri_len - 1] != '/') {
         /* URI: /path_to_script/script.cgi */
         addenv(env, "SCRIPT_NAME=%s", conn->request_info.local_uri);
      } else {
         /* URI: /path_to_script/ ... using index.cgi */
         const char *index_file = strrchr(prog, '/');
         if (index_file) {
            addenv(env,
                   "SCRIPT_NAME=%s%s",
                   conn->request_info.local_uri,
                   index_file + 1);
         }
      }
   } else {
      /* URI: /path_to_script/script.cgi/path_info */
      addenv(env,
             "SCRIPT_NAME=%.*s",
             uri_len - (int)strlen(conn->path_info),
             conn->request_info.local_uri);
   }

   addenv(env, "SCRIPT_FILENAME=%s", prog);
   if (conn->path_info == NULL) {
      addenv(env, "PATH_TRANSLATED=%s", conn->dom_ctx->config[DOCUMENT_ROOT]);
   } else {
      addenv(env,
             "PATH_TRANSLATED=%s%s",
             conn->dom_ctx->config[DOCUMENT_ROOT],
             conn->path_info);
   }

   addenv(env, "HTTPS=%s", (conn->ssl == NULL) ? "off" : "on");

   if ((s = mg_get_header(conn, "Content-Type")) != NULL) {
      addenv(env, "CONTENT_TYPE=%s", s);
   }
   if (conn->request_info.query_string != NULL) {
      addenv(env, "QUERY_STRING=%s", conn->request_info.query_string);
   }
   if ((s = mg_get_header(conn, "Content-Length")) != NULL) {
      addenv(env, "CONTENT_LENGTH=%s", s);
   }
   if ((s = getenv("PATH")) != NULL) {
      addenv(env, "PATH=%s", s);
   }
   if (conn->path_info != NULL) {
      addenv(env, "PATH_INFO=%s", conn->path_info);
   }

   if (conn->status_code > 0) {
      /* CGI error handler should show the status code */
      addenv(env, "STATUS=%d", conn->status_code);
   }

#if defined(_WIN32)
   if ((s = getenv("COMSPEC")) != NULL) {
      addenv(env, "COMSPEC=%s", s);
   }
   if ((s = getenv("SYSTEMROOT")) != NULL) {
      addenv(env, "SYSTEMROOT=%s", s);
   }
   if ((s = getenv("SystemDrive")) != NULL) {
      addenv(env, "SystemDrive=%s", s);
   }
   if ((s = getenv("ProgramFiles")) != NULL) {
      addenv(env, "ProgramFiles=%s", s);
   }
   if ((s = getenv("ProgramFiles(x86)")) != NULL) {
      addenv(env, "ProgramFiles(x86)=%s", s);
   }
#else
   if ((s = getenv("LD_LIBRARY_PATH")) != NULL) {
      addenv(env, "LD_LIBRARY_PATH=%s", s);
   }
#endif /* _WIN32 */

   if ((s = getenv("PERLLIB")) != NULL) {
      addenv(env, "PERLLIB=%s", s);
   }

   if (conn->request_info.remote_user != NULL) {
      addenv(env, "REMOTE_USER=%s", conn->request_info.remote_user);
      addenv(env, "%s", "AUTH_TYPE=Digest");
   }

   /* Add all headers as HTTP_* variables */
   for (i = 0; i < conn->request_info.num_headers; i++) {

      (void)mg_snprintf(conn,
                        &truncated,
                        http_var_name,
                        sizeof(http_var_name),
                        "HTTP_%s",
                        conn->request_info.http_headers[i].name);

      if (truncated) {
         mg_cry_internal(conn,
                         "%s: HTTP header variable too long [%s]",
                         __func__,
                         conn->request_info.http_headers[i].name);
         continue;
      }

      /* Convert variable name into uppercase, and change - to _ */
      for (p = http_var_name; *p != '\0'; p++) {
         if (*p == '-') {
            *p = '_';
         }
         *p = (char)toupper(*(unsigned char *)p);
      }

      addenv(env,
             "%s=%s",
             http_var_name,
             conn->request_info.http_headers[i].value);
   }

   /* Add user-specified variables */
   s = conn->dom_ctx->config[CGI_ENVIRONMENT];
   while ((s = next_option(s, &var_vec, NULL)) != NULL) {
      addenv(env, "%.*s", (int)var_vec.len, var_vec.ptr);
   }

   env->var[env->varused] = NULL;
   env->buf[env->bufused] = '\0';

   return 0;
}


/* Data for CGI process control: PID and number of references */
struct process_control_data {
   pid_t pid;
   int references;
};

static int
abort_process(void *data)
{
   /* Waitpid checks for child status and won't work for a pid that does not
    * identify a child of the current process. Thus, if the pid is reused,
    * we will not affect a different process. */
   struct process_control_data *proc = (struct process_control_data *)data;
   int status = 0;
   int refs;
   pid_t ret_pid;

   ret_pid = waitpid(proc->pid, &status, WNOHANG);
   if ((ret_pid != (pid_t)-1) && (status == 0)) {
      /* Stop child process */
      DEBUG_TRACE("CGI timer: Stop child process %p\n", proc->pid);
      kill(proc->pid, SIGABRT);

      /* Wait until process is terminated (don't leave zombies) */
      while (waitpid(proc->pid, &status, 0) != (pid_t)-1) /* nop */
         ;
   } else {
      DEBUG_TRACE("CGI timer: Child process %p already stopped\n", proc->pid);
   }
   /* Dec reference counter */
   refs = mg_atomic_dec(&proc->references);
   if (refs == 0) {
      /* no more references - free data */
      mg_free(data);
   }

   return 0;
}


static void
handle_cgi_request(struct mg_connection *conn, const char *prog)
{
   char *buf;
   size_t buflen;
   int headers_len, data_len, i, truncated;
   int fdin[2] = {-1, -1}, fdout[2] = {-1, -1}, fderr[2] = {-1, -1};
   const char *status, *status_text, *connection_state;
   char *pbuf, dir[PATH_MAX], *p;
   struct mg_request_info ri;
   struct cgi_environment blk;
   FILE *in = NULL, *out = NULL, *err = NULL;
   struct mg_file fout = STRUCT_FILE_INITIALIZER;
   pid_t pid = (pid_t)-1;
   struct process_control_data *proc = NULL;

#if defined(USE_TIMERS)
   double cgi_timeout = -1.0;
   if (conn->dom_ctx->config[CGI_TIMEOUT]) {
      /* Get timeout in seconds */
      cgi_timeout = atof(conn->dom_ctx->config[CGI_TIMEOUT]) * 0.001;
   }
#endif

   if (conn == NULL) {
      return;
   }

   buf = NULL;
   buflen = conn->phys_ctx->max_request_size;
   i = prepare_cgi_environment(conn, prog, &blk);
   if (i != 0) {
      blk.buf = NULL;
      blk.var = NULL;
      goto done;
   }

   /* CGI must be executed in its own directory. 'dir' must point to the
    * directory containing executable program, 'p' must point to the
    * executable program name relative to 'dir'. */
   (void)mg_snprintf(conn, &truncated, dir, sizeof(dir), "%s", prog);

   if (truncated) {
      mg_cry_internal(conn, "Error: CGI program \"%s\": Path too long", prog);
      mg_send_http_error(conn, 500, "Error: %s", "CGI path too long");
      goto done;
   }

   if ((p = strrchr(dir, '/')) != NULL) {
      *p++ = '\0';
   } else {
      dir[0] = '.';
      dir[1] = '\0';
      p = (char *)prog;
   }

   if ((pipe(fdin) != 0) || (pipe(fdout) != 0) || (pipe(fderr) != 0)) {
      status = strerror(ERRNO);
      mg_cry_internal(
          conn,
          "Error: CGI program \"%s\": Can not create CGI pipes: %s",
          prog,
          status);
      mg_send_http_error(conn,
                         500,
                         "Error: Cannot create CGI pipe: %s",
                         status);
      goto done;
   }

   proc = (struct process_control_data *)
       mg_malloc_ctx(sizeof(struct process_control_data), conn->phys_ctx);
   if (proc == NULL) {
      mg_cry_internal(conn, "Error: CGI program \"%s\": Out or memory", prog);
      mg_send_http_error(conn, 500, "Error: Out of memory [%s]", prog);
      goto done;
   }

   DEBUG_TRACE("CGI: spawn %s %s\n", dir, p);
   pid = spawn_process(conn, p, blk.buf, blk.var, fdin, fdout, fderr, dir);

   if (pid == (pid_t)-1) {
      status = strerror(ERRNO);
      mg_cry_internal(
          conn,
          "Error: CGI program \"%s\": Can not spawn CGI process: %s",
          prog,
          status);
      mg_send_http_error(conn,
                         500,
                         "Error: Cannot spawn CGI process [%s]: %s",
                         prog,
                         status);
      mg_free(proc);
      proc = NULL;
      goto done;
   }

   /* Store data in shared process_control_data */
   proc->pid = pid;
   proc->references = 1;

#if defined(USE_TIMERS)
   if (cgi_timeout > 0.0) {
      proc->references = 2;

      // Start a timer for CGI
      timer_add(conn->phys_ctx,
                cgi_timeout /* in seconds */,
                0.0,
                1,
                abort_process,
                (void *)proc);
   }
#endif

   /* Make sure child closes all pipe descriptors. It must dup them to 0,1 */
   set_close_on_exec((SOCKET)fdin[0], conn);  /* stdin read */
   set_close_on_exec((SOCKET)fdin[1], conn);  /* stdin write */
   set_close_on_exec((SOCKET)fdout[0], conn); /* stdout read */
   set_close_on_exec((SOCKET)fdout[1], conn); /* stdout write */
   set_close_on_exec((SOCKET)fderr[0], conn); /* stderr read */
   set_close_on_exec((SOCKET)fderr[1], conn); /* stderr write */

   /* Parent closes only one side of the pipes.
    * If we don't mark them as closed, close() attempt before
    * return from this function throws an exception on Windows.
    * Windows does not like when closed descriptor is closed again. */
   (void)close(fdin[0]);
   (void)close(fdout[1]);
   (void)close(fderr[1]);
   fdin[0] = fdout[1] = fderr[1] = -1;

   if ((in = fdopen(fdin[1], "wb")) == NULL) {
      status = strerror(ERRNO);
      mg_cry_internal(conn,
                      "Error: CGI program \"%s\": Can not open stdin: %s",
                      prog,
                      status);
      mg_send_http_error(conn,
                         500,
                         "Error: CGI can not open fdin\nfopen: %s",
                         status);
      goto done;
   }

   if ((out = fdopen(fdout[0], "rb")) == NULL) {
      status = strerror(ERRNO);
      mg_cry_internal(conn,
                      "Error: CGI program \"%s\": Can not open stdout: %s",
                      prog,
                      status);
      mg_send_http_error(conn,
                         500,
                         "Error: CGI can not open fdout\nfopen: %s",
                         status);
      goto done;
   }

   if ((err = fdopen(fderr[0], "rb")) == NULL) {
      status = strerror(ERRNO);
      mg_cry_internal(conn,
                      "Error: CGI program \"%s\": Can not open stderr: %s",
                      prog,
                      status);
      mg_send_http_error(conn,
                         500,
                         "Error: CGI can not open fderr\nfopen: %s",
                         status);
      goto done;
   }

   setbuf(in, NULL);
   setbuf(out, NULL);
   setbuf(err, NULL);
   fout.access.fp = out;

   if ((conn->request_info.content_length != 0) || (conn->is_chunked)) {
      DEBUG_TRACE("CGI: send body data (%lli)\n",
                  (signed long long)conn->request_info.content_length);

      /* This is a POST/PUT request, or another request with body data. */
      if (!forward_body_data(conn, in, INVALID_SOCKET, NULL)) {
         /* Error sending the body data */
         mg_cry_internal(
             conn,
             "Error: CGI program \"%s\": Forward body data failed",
             prog);
         goto done;
      }
   }

   /* Close so child gets an EOF. */
   fclose(in);
   in = NULL;
   fdin[1] = -1;

   /* Now read CGI reply into a buffer. We need to set correct
    * status code, thus we need to see all HTTP headers first.
    * Do not send anything back to client, until we buffer in all
    * HTTP headers. */
   data_len = 0;
   buf = (char *)mg_malloc_ctx(buflen, conn->phys_ctx);
   if (buf == NULL) {
      mg_send_http_error(conn,
                         500,
                         "Error: Not enough memory for CGI buffer (%u bytes)",
                         (unsigned int)buflen);
      mg_cry_internal(
          conn,
          "Error: CGI program \"%s\": Not enough memory for buffer (%u "
          "bytes)",
          prog,
          (unsigned int)buflen);
      goto done;
   }

   DEBUG_TRACE("CGI: %s", "wait for response");
   headers_len = read_message(out, conn, buf, (int)buflen, &data_len);
   DEBUG_TRACE("CGI: response: %li", (signed long)headers_len);

   if (headers_len <= 0) {

      /* Could not parse the CGI response. Check if some error message on
       * stderr. */
      i = pull_all(err, conn, buf, (int)buflen);
      if (i > 0) {
         /* CGI program explicitly sent an error */
         /* Write the error message to the internal log */
         mg_cry_internal(conn,
                         "Error: CGI program \"%s\" sent error "
                         "message: [%.*s]",
                         prog,
                         i,
                         buf);
         /* Don't send the error message back to the client */
         mg_send_http_error(conn,
                            500,
                            "Error: CGI program \"%s\" failed.",
                            prog);
      } else {
         /* CGI program did not explicitly send an error, but a broken
          * respon header */
         mg_cry_internal(conn,
                         "Error: CGI program sent malformed or too big "
                         "(>%u bytes) HTTP headers: [%.*s]",
                         (unsigned)buflen,
                         data_len,
                         buf);

         mg_send_http_error(conn,
                            500,
                            "Error: CGI program sent malformed or too big "
                            "(>%u bytes) HTTP headers: [%.*s]",
                            (unsigned)buflen,
                            data_len,
                            buf);
      }

      /* in both cases, abort processing CGI */
      goto done;
   }

   pbuf = buf;
   buf[headers_len - 1] = '\0';
   ri.num_headers = parse_http_headers(&pbuf, ri.http_headers);

   /* Make up and send the status line */
   status_text = "OK";
   if ((status = get_header(ri.http_headers, ri.num_headers, "Status"))
       != NULL) {
      conn->status_code = atoi(status);
      status_text = status;
      while (isdigit(*(const unsigned char *)status_text)
             || *status_text == ' ') {
         status_text++;
      }
   } else if (get_header(ri.http_headers, ri.num_headers, "Location")
              != NULL) {
      conn->status_code = 307;
   } else {
      conn->status_code = 200;
   }
   connection_state =
       get_header(ri.http_headers, ri.num_headers, "Connection");
   if (!header_has_option(connection_state, "keep-alive")) {
      conn->must_close = 1;
   }

   DEBUG_TRACE("CGI: response %u %s", conn->status_code, status_text);

   (void)mg_printf(conn, "HTTP/1.1 %d %s\r\n", conn->status_code, status_text);

   /* Send headers */
   for (i = 0; i < ri.num_headers; i++) {
      mg_printf(conn,
                "%s: %s\r\n",
                ri.http_headers[i].name,
                ri.http_headers[i].value);
   }
   mg_write(conn, "\r\n", 2);

   /* Send chunk of data that may have been read after the headers */
   mg_write(conn, buf + headers_len, (size_t)(data_len - headers_len));

   /* Read the rest of CGI output and send to the client */
   DEBUG_TRACE("CGI: %s", "forward all data");
   send_file_data(conn, &fout, 0, INT64_MAX);
   DEBUG_TRACE("CGI: %s", "all data sent");

done:
   mg_free(blk.var);
   mg_free(blk.buf);

   if (pid != (pid_t)-1) {
      abort_process((void *)proc);
   }

   if (fdin[0] != -1) {
      close(fdin[0]);
   }
   if (fdout[1] != -1) {
      close(fdout[1]);
   }

   if (in != NULL) {
      fclose(in);
   } else if (fdin[1] != -1) {
      close(fdin[1]);
   }

   if (out != NULL) {
      fclose(out);
   } else if (fdout[0] != -1) {
      close(fdout[0]);
   }

   if (err != NULL) {
      fclose(err);
   } else if (fderr[0] != -1) {
      close(fderr[0]);
   }

   if (buf != NULL) {
      mg_free(buf);
   }
}
#endif /* !NO_CGI */


#if !defined(NO_FILES)
static void
mkcol(struct mg_connection *conn, const char *path)
{
   int rc, body_len;
   struct de de;
   char date[64];
   time_t curtime = time(NULL);

   if (conn == NULL) {
      return;
   }

   /* TODO (mid): Check the mg_send_http_error situations in this function
    */

   memset(&de.file, 0, sizeof(de.file));
   if (!mg_stat(conn, path, &de.file)) {
      mg_cry_internal(conn,
                      "%s: mg_stat(%s) failed: %s",
                      __func__,
                      path,
                      strerror(ERRNO));
   }

   if (de.file.last_modified) {
      /* TODO (mid): This check does not seem to make any sense ! */
      /* TODO (mid): Add a webdav unit test first, before changing
       * anything here. */
      mg_send_http_error(
          conn, 405, "Error: mkcol(%s): %s", path, strerror(ERRNO));
      return;
   }

   body_len = conn->data_len - conn->request_len;
   if (body_len > 0) {
      mg_send_http_error(
          conn, 415, "Error: mkcol(%s): %s", path, strerror(ERRNO));
      return;
   }

   rc = mg_mkdir(conn, path, 0755);

   if (rc == 0) {
      conn->status_code = 201;
      gmt_time_string(date, sizeof(date), &curtime);
      mg_printf(conn,
                "HTTP/1.1 %d Created\r\n"
                "Date: %s\r\n",
                conn->status_code,
                date);
      send_static_cache_header(conn);
      send_additional_header(conn);
      mg_printf(conn,
                "Content-Length: 0\r\n"
                "Connection: %s\r\n\r\n",
                suggest_connection_header(conn));
   } else {
      if (errno == EEXIST) {
         mg_send_http_error(
             conn, 405, "Error: mkcol(%s): %s", path, strerror(ERRNO));
      } else if (errno == EACCES) {
         mg_send_http_error(
             conn, 403, "Error: mkcol(%s): %s", path, strerror(ERRNO));
      } else if (errno == ENOENT) {
         mg_send_http_error(
             conn, 409, "Error: mkcol(%s): %s", path, strerror(ERRNO));
      } else {
         mg_send_http_error(
             conn, 500, "fopen(%s): %s", path, strerror(ERRNO));
      }
   }
}


static void
put_file(struct mg_connection *conn, const char *path)
{
   struct mg_file file = STRUCT_FILE_INITIALIZER;
   const char *range;
   int64_t r1, r2;
   int rc;
   char date[64];
   time_t curtime = time(NULL);

   if (conn == NULL) {
      return;
   }

   if (mg_stat(conn, path, &file.stat)) {
      /* File already exists */
      conn->status_code = 200;

      if (file.stat.is_directory) {
         /* This is an already existing directory,
          * so there is nothing to do for the server. */
         rc = 0;

      } else {
         /* File exists and is not a directory. */
         /* Can it be replaced? */

#if defined(MG_USE_OPEN_FILE)
         if (file.access.membuf != NULL) {
            /* This is an "in-memory" file, that can not be replaced */
            mg_send_http_error(conn,
                               405,
                               "Error: Put not possible\nReplacing %s "
                               "is not supported",
                               path);
            return;
         }
#endif

         /* Check if the server may write this file */
         if (access(path, W_OK) == 0) {
            /* Access granted */
            conn->status_code = 200;
            rc = 1;
         } else {
            mg_send_http_error(
                conn,
                403,
                "Error: Put not possible\nReplacing %s is not allowed",
                path);
            return;
         }
      }
   } else {
      /* File should be created */
      conn->status_code = 201;
      rc = put_dir(conn, path);
   }

   if (rc == 0) {
      /* put_dir returns 0 if path is a directory */
      gmt_time_string(date, sizeof(date), &curtime);
      mg_printf(conn,
                "HTTP/1.1 %d %s\r\n",
                conn->status_code,
                mg_get_response_code_text(NULL, conn->status_code));
      send_no_cache_header(conn);
      send_additional_header(conn);
      mg_printf(conn,
                "Date: %s\r\n"
                "Content-Length: 0\r\n"
                "Connection: %s\r\n\r\n",
                date,
                suggest_connection_header(conn));

      /* Request to create a directory has been fulfilled successfully.
       * No need to put a file. */
      return;
   }

   if (rc == -1) {
      /* put_dir returns -1 if the path is too long */
      mg_send_http_error(conn,
                         414,
                         "Error: Path too long\nput_dir(%s): %s",
                         path,
                         strerror(ERRNO));
      return;
   }

   if (rc == -2) {
      /* put_dir returns -2 if the directory can not be created */
      mg_send_http_error(conn,
                         500,
                         "Error: Can not create directory\nput_dir(%s): %s",
                         path,
                         strerror(ERRNO));
      return;
   }

   /* A file should be created or overwritten. */
   /* Currently CivetWeb does not nead read+write access. */
   if (!mg_fopen(conn, path, MG_FOPEN_MODE_WRITE, &file)
       || file.access.fp == NULL) {
      (void)mg_fclose(&file.access);
      mg_send_http_error(conn,
                         500,
                         "Error: Can not create file\nfopen(%s): %s",
                         path,
                         strerror(ERRNO));
      return;
   }

   fclose_on_exec(&file.access, conn);
   range = mg_get_header(conn, "Content-Range");
   r1 = r2 = 0;
   if ((range != NULL) && parse_range_header(range, &r1, &r2) > 0) {
      conn->status_code = 206; /* Partial content */
      fseeko(file.access.fp, r1, SEEK_SET);
   }

   if (!forward_body_data(conn, file.access.fp, INVALID_SOCKET, NULL)) {
      /* forward_body_data failed.
       * The error code has already been sent to the client,
       * and conn->status_code is already set. */
      (void)mg_fclose(&file.access);
      return;
   }

   if (mg_fclose(&file.access) != 0) {
      /* fclose failed. This might have different reasons, but a likely
       * one is "no space on disk", http 507. */
      conn->status_code = 507;
   }

   gmt_time_string(date, sizeof(date), &curtime);
   mg_printf(conn,
             "HTTP/1.1 %d %s\r\n",
             conn->status_code,
             mg_get_response_code_text(NULL, conn->status_code));
   send_no_cache_header(conn);
   send_additional_header(conn);
   mg_printf(conn,
             "Date: %s\r\n"
             "Content-Length: 0\r\n"
             "Connection: %s\r\n\r\n",
             date,
             suggest_connection_header(conn));
}


static void
delete_file(struct mg_connection *conn, const char *path)
{
   struct de de;
   memset(&de.file, 0, sizeof(de.file));
   if (!mg_stat(conn, path, &de.file)) {
      /* mg_stat returns 0 if the file does not exist */
      mg_send_http_error(conn,
                         404,
                         "Error: Cannot delete file\nFile %s not found",
                         path);
      return;
   }

#if 0 /* Ignore if a file in memory is inside a folder */
        if (de.access.membuf != NULL) {
                /* the file is cached in memory */
                mg_send_http_error(
                    conn,
                    405,
                    "Error: Delete not possible\nDeleting %s is not supported",
                    path);
                return;
        }
#endif

   if (de.file.is_directory) {
      if (remove_directory(conn, path)) {
         /* Delete is successful: Return 204 without content. */
         mg_send_http_error(conn, 204, "%s", "");
      } else {
         /* Delete is not successful: Return 500 (Server error). */
         mg_send_http_error(conn, 500, "Error: Could not delete %s", path);
      }
      return;
   }

   /* This is an existing file (not a directory).
    * Check if write permission is granted. */
   if (access(path, W_OK) != 0) {
      /* File is read only */
      mg_send_http_error(
          conn,
          403,
          "Error: Delete not possible\nDeleting %s is not allowed",
          path);
      return;
   }

   /* Try to delete it. */
   if (mg_remove(conn, path) == 0) {
      /* Delete was successful: Return 204 without content. */
      mg_send_http_error(conn, 204, "%s", "");
   } else {
      /* Delete not successful (file locked). */
      mg_send_http_error(conn,
                         423,
                         "Error: Cannot delete file\nremove(%s): %s",
                         path,
                         strerror(ERRNO));
   }
}
#endif /* !NO_FILES */


static void
send_ssi_file(struct mg_connection *, const char *, struct mg_file *, int);


static void
do_ssi_include(struct mg_connection *conn,
               const char *ssi,
               char *tag,
               int include_level)
{
   char file_name[MG_BUF_LEN], path[512], *p;
   struct mg_file file = STRUCT_FILE_INITIALIZER;
   size_t len;
   int truncated = 0;

   if (conn == NULL) {
      return;
   }

   /* sscanf() is safe here, since send_ssi_file() also uses buffer
    * of size MG_BUF_LEN to get the tag. So strlen(tag) is
    * always < MG_BUF_LEN. */
   if (sscanf(tag, " virtual=\"%511[^\"]\"", file_name) == 1) {
      /* File name is relative to the webserver root */
      file_name[511] = 0;
      (void)mg_snprintf(conn,
                        &truncated,
                        path,
                        sizeof(path),
                        "%s/%s",
                        conn->dom_ctx->config[DOCUMENT_ROOT],
                        file_name);

   } else if (sscanf(tag, " abspath=\"%511[^\"]\"", file_name) == 1) {
      /* File name is relative to the webserver working directory
       * or it is absolute system path */
      file_name[511] = 0;
      (void)
          mg_snprintf(conn, &truncated, path, sizeof(path), "%s", file_name);

   } else if ((sscanf(tag, " file=\"%511[^\"]\"", file_name) == 1)
              || (sscanf(tag, " \"%511[^\"]\"", file_name) == 1)) {
      /* File name is relative to the currect document */
      file_name[511] = 0;
      (void)mg_snprintf(conn, &truncated, path, sizeof(path), "%s", ssi);

      if (!truncated) {
         if ((p = strrchr(path, '/')) != NULL) {
            p[1] = '\0';
         }
         len = strlen(path);
         (void)mg_snprintf(conn,
                           &truncated,
                           path + len,
                           sizeof(path) - len,
                           "%s",
                           file_name);
      }

   } else {
      mg_cry_internal(conn, "Bad SSI #include: [%s]", tag);
      return;
   }

   if (truncated) {
      mg_cry_internal(conn, "SSI #include path length overflow: [%s]", tag);
      return;
   }

   if (!mg_fopen(conn, path, MG_FOPEN_MODE_READ, &file)) {
      mg_cry_internal(conn,
                      "Cannot open SSI #include: [%s]: fopen(%s): %s",
                      tag,
                      path,
                      strerror(ERRNO));
   } else {
      fclose_on_exec(&file.access, conn);
      if (match_prefix(conn->dom_ctx->config[SSI_EXTENSIONS],
                       strlen(conn->dom_ctx->config[SSI_EXTENSIONS]),
                       path)
          > 0) {
         send_ssi_file(conn, path, &file, include_level + 1);
      } else {
         send_file_data(conn, &file, 0, INT64_MAX);
      }
      (void)mg_fclose(&file.access); /* Ignore errors for readonly files */
   }
}


#if !defined(NO_POPEN)
static void
do_ssi_exec(struct mg_connection *conn, char *tag)
{
   char cmd[1024] = "";
   struct mg_file file = STRUCT_FILE_INITIALIZER;

   if (sscanf(tag, " \"%1023[^\"]\"", cmd) != 1) {
      mg_cry_internal(conn, "Bad SSI #exec: [%s]", tag);
   } else {
      cmd[1023] = 0;
      if ((file.access.fp = popen(cmd, "r")) == NULL) {
         mg_cry_internal(conn,
                         "Cannot SSI #exec: [%s]: %s",
                         cmd,
                         strerror(ERRNO));
      } else {
         send_file_data(conn, &file, 0, INT64_MAX);
         pclose(file.access.fp);
      }
   }
}
#endif /* !NO_POPEN */


static int
mg_fgetc(struct mg_file *filep, int offset)
{
   (void)offset; /* unused in case MG_USE_OPEN_FILE is set */

   if (filep == NULL) {
      return EOF;
   }
#if defined(MG_USE_OPEN_FILE)
   if ((filep->access.membuf != NULL) && (offset >= 0)
       && (((unsigned int)(offset)) < filep->stat.size)) {
      return ((const unsigned char *)filep->access.membuf)[offset];
   } else /* else block below */
#endif
       if (filep->access.fp != NULL) {
      return fgetc(filep->access.fp);
   } else {
      return EOF;
   }
}


static void
send_ssi_file(struct mg_connection *conn,
              const char *path,
              struct mg_file *filep,
              int include_level)
{
   char buf[MG_BUF_LEN];
   int ch, offset, len, in_tag, in_ssi_tag;

   if (include_level > 10) {
      mg_cry_internal(conn, "SSI #include level is too deep (%s)", path);
      return;
   }

   in_tag = in_ssi_tag = len = offset = 0;

   /* Read file, byte by byte, and look for SSI include tags */
   while ((ch = mg_fgetc(filep, offset++)) != EOF) {

      if (in_tag) {
         /* We are in a tag, either SSI tag or html tag */

         if (ch == '>') {
            /* Tag is closing */
            buf[len++] = '>';

            if (in_ssi_tag) {
               /* Handle SSI tag */
               buf[len] = 0;

               if ((len > 12) && !memcmp(buf + 5, "include", 7)) {
                  do_ssi_include(conn, path, buf + 12, include_level + 1);
#if !defined(NO_POPEN)
               } else if ((len > 9) && !memcmp(buf + 5, "exec", 4)) {
                  do_ssi_exec(conn, buf + 9);
#endif /* !NO_POPEN */
               } else {
                  mg_cry_internal(conn,
                                  "%s: unknown SSI "
                                  "command: \"%s\"",
                                  path,
                                  buf);
               }
               len = 0;
               in_ssi_tag = in_tag = 0;

            } else {
               /* Not an SSI tag */
               /* Flush buffer */
               (void)mg_write(conn, buf, (size_t)len);
               len = 0;
               in_tag = 0;
            }

         } else {
            /* Tag is still open */
            buf[len++] = (char)(ch & 0xff);

            if ((len == 5) && !memcmp(buf, "<!--#", 5)) {
               /* All SSI tags start with <!--# */
               in_ssi_tag = 1;
            }

            if ((len + 2) > (int)sizeof(buf)) {
               /* Tag to long for buffer */
               mg_cry_internal(conn, "%s: tag is too large", path);
               return;
            }
         }

      } else {

         /* We are not in a tag yet. */
         if (ch == '<') {
            /* Tag is opening */
            in_tag = 1;

            if (len > 0) {
               /* Flush current buffer.
                * Buffer is filled with "len" bytes. */
               (void)mg_write(conn, buf, (size_t)len);
            }
            /* Store the < */
            len = 1;
            buf[0] = '<';

         } else {
            /* No Tag */
            /* Add data to buffer */
            buf[len++] = (char)(ch & 0xff);
            /* Flush if buffer is full */
            if (len == (int)sizeof(buf)) {
               mg_write(conn, buf, (size_t)len);
               len = 0;
            }
         }
      }
   }

   /* Send the rest of buffered data */
   if (len > 0) {
      mg_write(conn, buf, (size_t)len);
   }
}


static void
handle_ssi_file_request(struct mg_connection *conn,
                        const char *path,
                        struct mg_file *filep)
{
   char date[64];
   time_t curtime = time(NULL);
   const char *cors1, *cors2, *cors3;

   if ((conn == NULL) || (path == NULL) || (filep == NULL)) {
      return;
   }

   if (mg_get_header(conn, "Origin")) {
      /* Cross-origin resource sharing (CORS). */
      cors1 = "Access-Control-Allow-Origin: ";
      cors2 = conn->dom_ctx->config[ACCESS_CONTROL_ALLOW_ORIGIN];
      cors3 = "\r\n";
   } else {
      cors1 = cors2 = cors3 = "";
   }

   if (!mg_fopen(conn, path, MG_FOPEN_MODE_READ, filep)) {
      /* File exists (precondition for calling this function),
       * but can not be opened by the server. */
      mg_send_http_error(conn,
                         500,
                         "Error: Cannot read file\nfopen(%s): %s",
                         path,
                         strerror(ERRNO));
   } else {
      conn->must_close = 1;
      gmt_time_string(date, sizeof(date), &curtime);
      fclose_on_exec(&filep->access, conn);
      mg_printf(conn, "HTTP/1.1 200 OK\r\n");
      send_no_cache_header(conn);
      send_additional_header(conn);
      mg_printf(conn,
                "%s%s%s"
                "Date: %s\r\n"
                "Content-Type: text/html\r\n"
                "Connection: %s\r\n\r\n",
                cors1,
                cors2,
                cors3,
                date,
                suggest_connection_header(conn));
      send_ssi_file(conn, path, filep, 0);
      (void)mg_fclose(&filep->access); /* Ignore errors for readonly files */
   }
}


#if !defined(NO_FILES)
static void
send_options(struct mg_connection *conn)
{
   char date[64];
   time_t curtime = time(NULL);

   if (!conn) {
      return;
   }

   conn->status_code = 200;
   conn->must_close = 1;
   gmt_time_string(date, sizeof(date), &curtime);

   /* We do not set a "Cache-Control" header here, but leave the default.
    * Since browsers do not send an OPTIONS request, we can not test the
    * effect anyway. */
   mg_printf(conn,
             "HTTP/1.1 200 OK\r\n"
             "Date: %s\r\n"
             "Connection: %s\r\n"
             "Allow: GET, POST, HEAD, CONNECT, PUT, DELETE, OPTIONS, "
             "PROPFIND, MKCOL\r\n"
             "DAV: 1\r\n",
             date,
             suggest_connection_header(conn));
   send_additional_header(conn);
   mg_printf(conn, "\r\n");
}


/* Writes PROPFIND properties for a collection element */
static void
print_props(struct mg_connection *conn,
            const char *uri,
            struct mg_file_stat *filep)
{
   char mtime[64];

   if ((conn == NULL) || (uri == NULL) || (filep == NULL)) {
      return;
   }

   gmt_time_string(mtime, sizeof(mtime), &filep->last_modified);
   mg_printf(conn,
             "<d:response>"
             "<d:href>%s</d:href>"
             "<d:propstat>"
             "<d:prop>"
             "<d:resourcetype>%s</d:resourcetype>"
             "<d:getcontentlength>%" INT64_FMT "</d:getcontentlength>"
             "<d:getlastmodified>%s</d:getlastmodified>"
             "</d:prop>"
             "<d:status>HTTP/1.1 200 OK</d:status>"
             "</d:propstat>"
             "</d:response>\n",
             uri,
             filep->is_directory ? "<d:collection/>" : "",
             filep->size,
             mtime);
}


static int
print_dav_dir_entry(struct de *de, void *data)
{
   char href[PATH_MAX];
   int truncated;

   struct mg_connection *conn = (struct mg_connection *)data;
   if (!de || !conn) {
      return -1;
   }
   mg_snprintf(conn,
               &truncated,
               href,
               sizeof(href),
               "%s%s",
               conn->request_info.local_uri,
               de->file_name);

   if (!truncated) {
      size_t href_encoded_size;
      char *href_encoded;

      href_encoded_size = PATH_MAX * 3; /* worst case */
      href_encoded = (char *)mg_malloc(href_encoded_size);
      if (href_encoded == NULL) {
         return -1;
      }
      mg_url_encode(href, href_encoded, href_encoded_size);
      print_props(conn, href_encoded, &de->file);
      mg_free(href_encoded);
   }

   return 0;
}


static void
handle_propfind(struct mg_connection *conn,
                const char *path,
                struct mg_file_stat *filep)
{
   const char *depth = mg_get_header(conn, "Depth");
   char date[64];
   time_t curtime = time(NULL);

   gmt_time_string(date, sizeof(date), &curtime);

   if (!conn || !path || !filep || !conn->dom_ctx) {
      return;
   }

   conn->must_close = 1;
   conn->status_code = 207;
   mg_printf(conn,
             "HTTP/1.1 207 Multi-Status\r\n"
             "Date: %s\r\n",
             date);
   send_static_cache_header(conn);
   send_additional_header(conn);
   mg_printf(conn,
             "Connection: %s\r\n"
             "Content-Type: text/xml; charset=utf-8\r\n\r\n",
             suggest_connection_header(conn));

   mg_printf(conn,
             "<?xml version=\"1.0\" encoding=\"utf-8\"?>"
             "<d:multistatus xmlns:d='DAV:'>\n");

   /* Print properties for the requested resource itself */
   print_props(conn, conn->request_info.local_uri, filep);

   /* If it is a directory, print directory entries too if Depth is not 0
    */
   if (filep->is_directory
       && !mg_strcasecmp(conn->dom_ctx->config[ENABLE_DIRECTORY_LISTING],
                         "yes")
       && ((depth == NULL) || (strcmp(depth, "0") != 0))) {
      scan_directory(conn, path, conn, &print_dav_dir_entry);
   }

   mg_printf(conn, "%s\n", "</d:multistatus>");
}
#endif

void
mg_lock_connection(struct mg_connection *conn)
{
   if (conn) {
      (void)pthread_mutex_lock(&conn->mutex);
   }
}

void
mg_unlock_connection(struct mg_connection *conn)
{
   if (conn) {
      (void)pthread_mutex_unlock(&conn->mutex);
   }
}

void
mg_lock_context(struct mg_context *ctx)
{
   if (ctx) {
      (void)pthread_mutex_lock(&ctx->nonce_mutex);
   }
}

void
mg_unlock_context(struct mg_context *ctx)
{
   if (ctx) {
      (void)pthread_mutex_unlock(&ctx->nonce_mutex);
   }
}


#if defined(USE_LUA)
#include "mod_lua.inl"
#endif /* USE_LUA */

#if defined(USE_DUKTAPE)
#include "mod_duktape.inl"
#endif /* USE_DUKTAPE */

#if defined(USE_WEBSOCKET)

#if !defined(NO_SSL_DL)
#define SHA_API static
#include "sha1.inl"
#endif

static int
send_websocket_handshake(struct mg_connection *conn, const char *websock_key)
{
   static const char *magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
   char buf[100], sha[20], b64_sha[sizeof(sha) * 2];
   SHA_CTX sha_ctx;
   int truncated;

   /* Calculate Sec-WebSocket-Accept reply from Sec-WebSocket-Key. */
   mg_snprintf(conn, &truncated, buf, sizeof(buf), "%s%s", websock_key, magic);
   if (truncated) {
      conn->must_close = 1;
      return 0;
   }

   DEBUG_TRACE("%s", "Send websocket handshake");

   SHA1_Init(&sha_ctx);
   SHA1_Update(&sha_ctx, (unsigned char *)buf, (uint32_t)strlen(buf));
   SHA1_Final((unsigned char *)sha, &sha_ctx);
   base64_encode((unsigned char *)sha, sizeof(sha), b64_sha);
   mg_printf(conn,
             "HTTP/1.1 101 Switching Protocols\r\n"
             "Upgrade: websocket\r\n"
             "Connection: Upgrade\r\n"
             "Sec-WebSocket-Accept: %s\r\n",
             b64_sha);
   if (conn->request_info.acceptedWebSocketSubprotocol) {
      mg_printf(conn,
                "Sec-WebSocket-Protocol: %s\r\n\r\n",
                conn->request_info.acceptedWebSocketSubprotocol);
   } else {
      mg_printf(conn, "%s", "\r\n");
   }

   return 1;
}


#if !defined(MG_MAX_UNANSWERED_PING)
/* Configuration of the maximum number of websocket PINGs that might
 * stay unanswered before the connection is considered broken.
 * Note: The name of this define may still change (until it is
 * defined as a compile parameter in a documentation).
 */
#define MG_MAX_UNANSWERED_PING (5)
#endif


static void
read_websocket(struct mg_connection *conn,
               mg_websocket_data_handler ws_data_handler,
               void *callback_data)
{
   /* Pointer to the beginning of the portion of the incoming websocket
    * message queue.
    * The original websocket upgrade request is never removed, so the queue
    * begins after it. */
   unsigned char *buf = (unsigned char *)conn->buf + conn->request_len;
   int n, error, exit_by_callback;
   int ret;

   /* body_len is the length of the entire queue in bytes
    * len is the length of the current message
    * data_len is the length of the current message's data payload
    * header_len is the length of the current message's header */
   size_t i, len, mask_len = 0, header_len, body_len;
   uint64_t data_len = 0;

   /* "The masking key is a 32-bit value chosen at random by the client."
    * http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-17#section-5
    */
   unsigned char mask[4];

   /* data points to the place where the message is stored when passed to
    * the websocket_data callback.  This is either mem on the stack, or a
    * dynamically allocated buffer if it is too large. */
   unsigned char mem[4096];
   unsigned char mop; /* mask flag and opcode */


   /* Variables used for connection monitoring */
   double timeout = -1.0;
   int enable_ping_pong = 0;
   int ping_count = 0;

   if (conn->dom_ctx->config[ENABLE_WEBSOCKET_PING_PONG]) {
      enable_ping_pong =
          !mg_strcasecmp(conn->dom_ctx->config[ENABLE_WEBSOCKET_PING_PONG],
                         "yes");
   }

   if (conn->dom_ctx->config[WEBSOCKET_TIMEOUT]) {
      timeout = atoi(conn->dom_ctx->config[WEBSOCKET_TIMEOUT]) / 1000.0;
   }
   if ((timeout <= 0.0) && (conn->dom_ctx->config[REQUEST_TIMEOUT])) {
      timeout = atoi(conn->dom_ctx->config[REQUEST_TIMEOUT]) / 1000.0;
   }

   /* Enter data processing loop */
   DEBUG_TRACE("Websocket connection %s:%u start data processing loop",
               conn->request_info.remote_addr,
               conn->request_info.remote_port);
   conn->in_websocket_handling = 1;
   mg_set_thread_name("wsock");

   /* Loop continuously, reading messages from the socket, invoking the
    * callback, and waiting repeatedly until an error occurs. */
   while (!conn->phys_ctx->stop_flag && !conn->must_close) {
      header_len = 0;
      DEBUG_ASSERT(conn->data_len >= conn->request_len);
      if ((body_len = (size_t)(conn->data_len - conn->request_len)) >= 2) {
         len = buf[1] & 127;
         mask_len = (buf[1] & 128) ? 4 : 0;
         if ((len < 126) && (body_len >= mask_len)) {
            /* inline 7-bit length field */
            data_len = len;
            header_len = 2 + mask_len;
         } else if ((len == 126) && (body_len >= (4 + mask_len))) {
            /* 16-bit length field */
            header_len = 4 + mask_len;
            data_len = ((((size_t)buf[2]) << 8) + buf[3]);
         } else if (body_len >= (10 + mask_len)) {
            /* 64-bit length field */
            uint32_t l1, l2;
            memcpy(&l1, &buf[2], 4); /* Use memcpy for alignment */
            memcpy(&l2, &buf[6], 4);
            header_len = 10 + mask_len;
            data_len = (((uint64_t)ntohl(l1)) << 32) + ntohl(l2);

            if (data_len > (uint64_t)0x7FFF0000ul) {
               /* no can do */
               mg_cry_internal(
                   conn,
                   "%s",
                   "websocket out of memory; closing connection");
               break;
            }
         }
      }

      if ((header_len > 0) && (body_len >= header_len)) {
         /* Allocate space to hold websocket payload */
         unsigned char *data = mem;

         if ((size_t)data_len > (size_t)sizeof(mem)) {
            data = (unsigned char *)mg_malloc_ctx((size_t)data_len,
                                                  conn->phys_ctx);
            if (data == NULL) {
               /* Allocation failed, exit the loop and then close the
                * connection */
               mg_cry_internal(
                   conn,
                   "%s",
                   "websocket out of memory; closing connection");
               break;
            }
         }

         /* Copy the mask before we shift the queue and destroy it */
         if (mask_len > 0) {
            memcpy(mask, buf + header_len - mask_len, sizeof(mask));
         } else {
            memset(mask, 0, sizeof(mask));
         }

         /* Read frame payload from the first message in the queue into
          * data and advance the queue by moving the memory in place. */
         DEBUG_ASSERT(body_len >= header_len);
         if (data_len + (uint64_t)header_len > (uint64_t)body_len) {
            mop = buf[0]; /* current mask and opcode */
            /* Overflow case */
            len = body_len - header_len;
            memcpy(data, buf + header_len, len);
            error = 0;
            while ((uint64_t)len < data_len) {
               n = pull_inner(NULL,
                              conn,
                              (char *)(data + len),
                              (int)(data_len - len),
                              timeout);
               if (n <= -2) {
                  error = 1;
                  break;
               } else if (n > 0) {
                  len += (size_t)n;
               } else {
                  /* Timeout: should retry */
                  /* TODO: retry condition */
               }
            }
            if (error) {
               mg_cry_internal(
                   conn,
                   "%s",
                   "Websocket pull failed; closing connection");
               if (data != mem) {
                  mg_free(data);
               }
               break;
            }

            conn->data_len = conn->request_len;

         } else {

            mop = buf[0]; /* current mask and opcode, overwritten by
                           * memmove() */

            /* Length of the message being read at the front of the
             * queue. Cast to 31 bit is OK, since we limited
             * data_len before. */
            len = (size_t)data_len + header_len;

            /* Copy the data payload into the data pointer for the
             * callback. Cast to 31 bit is OK, since we
             * limited data_len */
            memcpy(data, buf + header_len, (size_t)data_len);

            /* Move the queue forward len bytes */
            memmove(buf, buf + len, body_len - len);

            /* Mark the queue as advanced */
            conn->data_len -= (int)len;
         }

         /* Apply mask if necessary */
         if (mask_len > 0) {
            for (i = 0; i < (size_t)data_len; i++) {
               data[i] ^= mask[i & 3];
            }
         }

         exit_by_callback = 0;
         if (enable_ping_pong && ((mop & 0xF) == MG_WEBSOCKET_OPCODE_PONG)) {
            /* filter PONG messages */
            DEBUG_TRACE("PONG from %s:%u",
                        conn->request_info.remote_addr,
                        conn->request_info.remote_port);
            /* No unanwered PINGs left */
            ping_count = 0;
         } else if (enable_ping_pong
                    && ((mop & 0xF) == MG_WEBSOCKET_OPCODE_PING)) {
            /* reply PING messages */
            DEBUG_TRACE("Reply PING from %s:%u",
                        conn->request_info.remote_addr,
                        conn->request_info.remote_port);
            ret = mg_websocket_write(conn,
                                     MG_WEBSOCKET_OPCODE_PONG,
                                     (char *)data,
                                     (size_t)data_len);
            if (ret <= 0) {
               /* Error: send failed */
               DEBUG_TRACE("Reply PONG failed (%i)", ret);
               break;
            }


         } else {
            /* Exit the loop if callback signals to exit (server side),
             * or "connection close" opcode received (client side). */
            if ((ws_data_handler != NULL)
                && !ws_data_handler(conn,
                                    mop,
                                    (char *)data,
                                    (size_t)data_len,
                                    callback_data)) {
               exit_by_callback = 1;
            }
         }

         /* It a buffer has been allocated, free it again */
         if (data != mem) {
            mg_free(data);
         }

         if (exit_by_callback) {
            DEBUG_TRACE("Callback requests to close connection from %s:%u",
                        conn->request_info.remote_addr,
                        conn->request_info.remote_port);
            break;
         }
         if ((mop & 0xf) == MG_WEBSOCKET_OPCODE_CONNECTION_CLOSE) {
            /* Opcode == 8, connection close */
            DEBUG_TRACE("Message requests to close connection from %s:%u",
                        conn->request_info.remote_addr,
                        conn->request_info.remote_port);
            break;
         }

         /* Not breaking the loop, process next websocket frame. */
      } else {
         /* Read from the socket into the next available location in the
          * message queue. */
         n = pull_inner(NULL,
                        conn,
                        conn->buf + conn->data_len,
                        conn->buf_size - conn->data_len,
                        timeout);
         if (n <= -2) {
            /* Error, no bytes read */
            DEBUG_TRACE("PULL from %s:%u failed",
                        conn->request_info.remote_addr,
                        conn->request_info.remote_port);
            break;
         }
         if (n > 0) {
            conn->data_len += n;
            /* Reset open PING count */
            ping_count = 0;
         } else {
            if (!conn->phys_ctx->stop_flag && !conn->must_close) {
               if (ping_count > MG_MAX_UNANSWERED_PING) {
                  /* Stop sending PING */
                  DEBUG_TRACE("Too many (%i) unanswered ping from %s:%u "
                              "- closing connection",
                              ping_count,
                              conn->request_info.remote_addr,
                              conn->request_info.remote_port);
                  break;
               }
               if (enable_ping_pong) {
                  /* Send Websocket PING message */
                  DEBUG_TRACE("PING to %s:%u",
                              conn->request_info.remote_addr,
                              conn->request_info.remote_port);
                  ret = mg_websocket_write(conn,
                                           MG_WEBSOCKET_OPCODE_PING,
                                           NULL,
                                           0);

                  if (ret <= 0) {
                     /* Error: send failed */
                     DEBUG_TRACE("Send PING failed (%i)", ret);
                     break;
                  }
                  ping_count++;
               }
            }
            /* Timeout: should retry */
            /* TODO: get timeout def */
         }
      }
   }

   /* Leave data processing loop */
   mg_set_thread_name("worker");
   conn->in_websocket_handling = 0;
   DEBUG_TRACE("Websocket connection %s:%u left data processing loop",
               conn->request_info.remote_addr,
               conn->request_info.remote_port);
}


static int
mg_websocket_write_exec(struct mg_connection *conn,
                        int opcode,
                        const char *data,
                        size_t dataLen,
                        uint32_t masking_key)
{
   unsigned char header[14];
   size_t headerLen;
   int retval;

#if defined(GCC_DIAGNOSTIC)
/* Disable spurious conversion warning for GCC */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wconversion"
#endif

   header[0] = 0x80u | (unsigned char)((unsigned)opcode & 0xf);

#if defined(GCC_DIAGNOSTIC)
#pragma GCC diagnostic pop
#endif

   /* Frame format: http://tools.ietf.org/html/rfc6455#section-5.2 */
   if (dataLen < 126) {
      /* inline 7-bit length field */
      header[1] = (unsigned char)dataLen;
      headerLen = 2;
   } else if (dataLen <= 0xFFFF) {
      /* 16-bit length field */
      uint16_t len = htons((uint16_t)dataLen);
      header[1] = 126;
      memcpy(header + 2, &len, 2);
      headerLen = 4;
   } else {
      /* 64-bit length field */
      uint32_t len1 = htonl((uint32_t)((uint64_t)dataLen >> 32));
      uint32_t len2 = htonl((uint32_t)(dataLen & 0xFFFFFFFFu));
      header[1] = 127;
      memcpy(header + 2, &len1, 4);
      memcpy(header + 6, &len2, 4);
      headerLen = 10;
   }

   if (masking_key) {
      /* add mask */
      header[1] |= 0x80;
      memcpy(header + headerLen, &masking_key, 4);
      headerLen += 4;
   }

   /* Note that POSIX/Winsock's send() is threadsafe
    * http://stackoverflow.com/questions/1981372/are-parallel-calls-to-send-recv-on-the-same-socket-valid
    * but mongoose's mg_printf/mg_write is not (because of the loop in
    * push(), although that is only a problem if the packet is large or
    * outgoing buffer is full). */

   /* TODO: Check if this lock should be moved to user land.
    * Currently the server sets this lock for websockets, but
    * not for any other connection. It must be set for every
    * conn read/written by more than one thread, no matter if
    * it is a websocket or regular connection. */
   (void)mg_lock_connection(conn);

   retval = mg_write(conn, header, headerLen);
   if (retval != (int)headerLen) {
      /* Did not send complete header */
      retval = -1;
   } else {
      if (dataLen > 0) {
         retval = mg_write(conn, data, dataLen);
      }
      /* if dataLen == 0, the header length (2) is returned */
   }

   /* TODO: Remove this unlock as well, when lock is removed. */
   mg_unlock_connection(conn);

   return retval;
}

int
mg_websocket_write(struct mg_connection *conn,
                   int opcode,
                   const char *data,
                   size_t dataLen)
{
   return mg_websocket_write_exec(conn, opcode, data, dataLen, 0);
}


static void
mask_data(const char *in, size_t in_len, uint32_t masking_key, char *out)
{
   size_t i = 0;

   i = 0;
   if ((in_len > 3) && ((ptrdiff_t)in % 4) == 0) {
      /* Convert in 32 bit words, if data is 4 byte aligned */
      while (i < (in_len - 3)) {
         *(uint32_t *)(void *)(out + i) =
             *(uint32_t *)(void *)(in + i) ^ masking_key;
         i += 4;
      }
   }
   if (i != in_len) {
      /* convert 1-3 remaining bytes if ((dataLen % 4) != 0)*/
      while (i < in_len) {
         *(uint8_t *)(void *)(out + i) =
             *(uint8_t *)(void *)(in + i)
             ^ *(((uint8_t *)&masking_key) + (i % 4));
         i++;
      }
   }
}


int
mg_websocket_client_write(struct mg_connection *conn,
                          int opcode,
                          const char *data,
                          size_t dataLen)
{
   int retval = -1;
   char *masked_data =
       (char *)mg_malloc_ctx(((dataLen + 7) / 4) * 4, conn->phys_ctx);
   uint32_t masking_key = 0;

   if (masked_data == NULL) {
      /* Return -1 in an error case */
      mg_cry_internal(conn,
                      "%s",
                      "Cannot allocate buffer for masked websocket response: "
                      "Out of memory");
      return -1;
   }

   do {
      /* Get a masking key - but not 0 */
      masking_key = (uint32_t)get_random();
   } while (masking_key == 0);

   mask_data(data, dataLen, masking_key, masked_data);

   retval = mg_websocket_write_exec(
       conn, opcode, masked_data, dataLen, masking_key);
   mg_free(masked_data);

   return retval;
}


static void
handle_websocket_request(struct mg_connection *conn,
                         const char *path,
                         int is_callback_resource,
                         struct mg_websocket_subprotocols *subprotocols,
                         mg_websocket_connect_handler ws_connect_handler,
                         mg_websocket_ready_handler ws_ready_handler,
                         mg_websocket_data_handler ws_data_handler,
                         mg_websocket_close_handler ws_close_handler,
                         void *cbData)
{
   const char *websock_key = mg_get_header(conn, "Sec-WebSocket-Key");
   const char *version = mg_get_header(conn, "Sec-WebSocket-Version");
   ptrdiff_t lua_websock = 0;

#if !defined(USE_LUA)
   (void)path;
#endif

   /* Step 1: Check websocket protocol version. */
   /* Step 1.1: Check Sec-WebSocket-Key. */
   if (!websock_key) {
      /* The RFC standard version (https://tools.ietf.org/html/rfc6455)
       * requires a Sec-WebSocket-Key header.
       */
      /* It could be the hixie draft version
       * (http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-76).
       */
      const char *key1 = mg_get_header(conn, "Sec-WebSocket-Key1");
      const char *key2 = mg_get_header(conn, "Sec-WebSocket-Key2");
      char key3[8];

      if ((key1 != NULL) && (key2 != NULL)) {
         /* This version uses 8 byte body data in a GET request */
         conn->content_len = 8;
         if (8 == mg_read(conn, key3, 8)) {
            /* This is the hixie version */
            mg_send_http_error(conn,
                               426,
                               "%s",
                               "Protocol upgrade to RFC 6455 required");
            return;
         }
      }
      /* This is an unknown version */
      mg_send_http_error(conn, 400, "%s", "Malformed websocket request");
      return;
   }

   /* Step 1.2: Check websocket protocol version. */
   /* The RFC version (https://tools.ietf.org/html/rfc6455) is 13. */
   if ((version == NULL) || (strcmp(version, "13") != 0)) {
      /* Reject wrong versions */
      mg_send_http_error(conn, 426, "%s", "Protocol upgrade required");
      return;
   }

   /* Step 1.3: Could check for "Host", but we do not really nead this
    * value for anything, so just ignore it. */

   /* Step 2: If a callback is responsible, call it. */
   if (is_callback_resource) {
      /* Step 2.1 check and select subprotocol */
      const char *protocols[64]; // max 64 headers
      int nbSubprotocolHeader = get_req_headers(&conn->request_info,
                                                "Sec-WebSocket-Protocol",
                                                protocols,
                                                64);
      if ((nbSubprotocolHeader > 0) && subprotocols) {
         int cnt = 0;
         int idx;
         unsigned long len;
         const char *sep, *curSubProtocol,
             *acceptedWebSocketSubprotocol = NULL;


         /* look for matching subprotocol */
         do {
            const char *protocol = protocols[cnt];

            do {
               sep = strchr(protocol, ',');
               curSubProtocol = protocol;
               len = sep ? (unsigned long)(sep - protocol)
                         : (unsigned long)strlen(protocol);
               while (sep && isspace(*++sep))
                  ; // ignore leading whitespaces
               protocol = sep;


               for (idx = 0; idx < subprotocols->nb_subprotocols; idx++) {
                  if ((strlen(subprotocols->subprotocols[idx]) == len)
                      && (strncmp(curSubProtocol,
                                  subprotocols->subprotocols[idx],
                                  len)
                          == 0)) {
                     acceptedWebSocketSubprotocol =
                         subprotocols->subprotocols[idx];
                     break;
                  }
               }
            } while (sep && !acceptedWebSocketSubprotocol);
         } while (++cnt < nbSubprotocolHeader
                  && !acceptedWebSocketSubprotocol);

         conn->request_info.acceptedWebSocketSubprotocol =
             acceptedWebSocketSubprotocol;

      } else if (nbSubprotocolHeader > 0) {
         /* keep legacy behavior */
         const char *protocol = protocols[0];

         /* The protocol is a comma separated list of names. */
         /* The server must only return one value from this list. */
         /* First check if it is a list or just a single value. */
         const char *sep = strrchr(protocol, ',');
         if (sep == NULL) {
            /* Just a single protocol -> accept it. */
            conn->request_info.acceptedWebSocketSubprotocol = protocol;
         } else {
            /* Multiple protocols -> accept the last one. */
            /* This is just a quick fix if the client offers multiple
             * protocols. The handler should have a list of accepted
             * protocols on his own
             * and use it to select one protocol among those the client
             * has
             * offered.
             */
            while (isspace(*++sep)) {
               ; /* ignore leading whitespaces */
            }
            conn->request_info.acceptedWebSocketSubprotocol = sep;
         }
      }

      if ((ws_connect_handler != NULL)
          && (ws_connect_handler(conn, cbData) != 0)) {
         /* C callback has returned non-zero, do not proceed with
          * handshake.
          */
         /* Note that C callbacks are no longer called when Lua is
          * responsible, so C can no longer filter callbacks for Lua. */
         return;
      }
   }

#if defined(USE_LUA)
   /* Step 3: No callback. Check if Lua is responsible. */
   else {
      /* Step 3.1: Check if Lua is responsible. */
      if (conn->dom_ctx->config[LUA_WEBSOCKET_EXTENSIONS]) {
         lua_websock = match_prefix(
             conn->dom_ctx->config[LUA_WEBSOCKET_EXTENSIONS],
             strlen(conn->dom_ctx->config[LUA_WEBSOCKET_EXTENSIONS]),
             path);
      }

      if (lua_websock) {
         /* Step 3.2: Lua is responsible: call it. */
         conn->lua_websocket_state = lua_websocket_new(path, conn);
         if (!conn->lua_websocket_state) {
            /* Lua rejected the new client */
            return;
         }
      }
   }
#endif

   /* Step 4: Check if there is a responsible websocket handler. */
   if (!is_callback_resource && !lua_websock) {
      /* There is no callback, and Lua is not responsible either. */
      /* Reply with a 404 Not Found. We are still at a standard
       * HTTP request here, before the websocket handshake, so
       * we can still send standard HTTP error replies. */
      mg_send_http_error(conn, 404, "%s", "Not found");
      return;
   }

   /* Step 5: The websocket connection has been accepted */
   if (!send_websocket_handshake(conn, websock_key)) {
      mg_send_http_error(conn, 500, "%s", "Websocket handshake failed");
      return;
   }

   /* Step 6: Call the ready handler */
   if (is_callback_resource) {
      if (ws_ready_handler != NULL) {
         ws_ready_handler(conn, cbData);
      }
#if defined(USE_LUA)
   } else if (lua_websock) {
      if (!lua_websocket_ready(conn, conn->lua_websocket_state)) {
         /* the ready handler returned false */
         return;
      }
#endif
   }

   /* Step 7: Enter the read loop */
   if (is_callback_resource) {
      read_websocket(conn, ws_data_handler, cbData);
#if defined(USE_LUA)
   } else if (lua_websock) {
      read_websocket(conn, lua_websocket_data, conn->lua_websocket_state);
#endif
   }

   /* Step 8: Call the close handler */
   if (ws_close_handler) {
      ws_close_handler(conn, cbData);
   }
}


static int
is_websocket_protocol(const struct mg_connection *conn)
{
   const char *upgrade, *connection;

   /* A websocket protocoll has the following HTTP headers:
    *
    * Connection: Upgrade
    * Upgrade: Websocket
    */

   upgrade = mg_get_header(conn, "Upgrade");
   if (upgrade == NULL) {
      return 0; /* fail early, don't waste time checking other header
                 * fields
                 */
   }
   if (!mg_strcasestr(upgrade, "websocket")) {
      return 0;
   }

   connection = mg_get_header(conn, "Connection");
   if (connection == NULL) {
      return 0;
   }
   if (!mg_strcasestr(connection, "upgrade")) {
      return 0;
   }

   /* The headers "Host", "Sec-WebSocket-Key", "Sec-WebSocket-Protocol" and
    * "Sec-WebSocket-Version" are also required.
    * Don't check them here, since even an unsupported websocket protocol
    * request still IS a websocket request (in contrast to a standard HTTP
    * request). It will fail later in handle_websocket_request.
    */

   return 1;
}
#endif /* !USE_WEBSOCKET */


static int
isbyte(int n)
{
   return (n >= 0) && (n <= 255);
}


static int
parse_net(const char *spec, uint32_t *net, uint32_t *mask)
{
   int n, a, b, c, d, slash = 32, len = 0;

   if (((sscanf(spec, "%d.%d.%d.%d/%d%n", &a, &b, &c, &d, &slash, &n) == 5)
        || (sscanf(spec, "%d.%d.%d.%d%n", &a, &b, &c, &d, &n) == 4))
       && isbyte(a) && isbyte(b) && isbyte(c) && isbyte(d) && (slash >= 0)
       && (slash < 33)) {
      len = n;
      *net = ((uint32_t)a << 24) | ((uint32_t)b << 16) | ((uint32_t)c << 8)
             | (uint32_t)d;
      *mask = slash ? (0xffffffffU << (32 - slash)) : 0;
   }

   return len;
}


static int
set_throttle(const char *spec, uint32_t remote_ip, const char *uri)
{
   int throttle = 0;
   struct vec vec, val;
   uint32_t net, mask;
   char mult;
   double v;

   while ((spec = next_option(spec, &vec, &val)) != NULL) {
      mult = ',';
      if ((val.ptr == NULL) || (sscanf(val.ptr, "%lf%c", &v, &mult) < 1)
          || (v < 0)
          || ((lowercase(&mult) != 'k') && (lowercase(&mult) != 'm')
              && (mult != ','))) {
         continue;
      }
      v *= (lowercase(&mult) == 'k')
               ? 1024
               : ((lowercase(&mult) == 'm') ? 1048576 : 1);
      if (vec.len == 1 && vec.ptr[0] == '*') {
         throttle = (int)v;
      } else if (parse_net(vec.ptr, &net, &mask) > 0) {
         if ((remote_ip & mask) == net) {
            throttle = (int)v;
         }
      } else if (match_prefix(vec.ptr, vec.len, uri) > 0) {
         throttle = (int)v;
      }
   }

   return throttle;
}


static uint32_t
get_remote_ip(const struct mg_connection *conn)
{
   if (!conn) {
      return 0;
   }
   return ntohl(*(const uint32_t *)&conn->client.rsa.sin.sin_addr);
}


/* The mg_upload function is superseeded by mg_handle_form_request. */
#include "handle_form.inl"


#if defined(MG_LEGACY_INTERFACE)
/* Implement the deprecated mg_upload function by calling the new
 * mg_handle_form_request function. While mg_upload could only handle
 * HTML forms sent as POST request in multipart/form-data format
 * containing only file input elements, mg_handle_form_request can
 * handle all form input elements and all standard request methods. */
struct mg_upload_user_data {
   struct mg_connection *conn;
   const char *destination_dir;
   int num_uploaded_files;
};


/* Helper function for deprecated mg_upload. */
static int
mg_upload_field_found(const char *key,
                      const char *filename,
                      char *path,
                      size_t pathlen,
                      void *user_data)
{
   int truncated = 0;
   struct mg_upload_user_data *fud = (struct mg_upload_user_data *)user_data;
   (void)key;

   if (!filename) {
      mg_cry_internal(fud->conn, "%s: No filename set", __func__);
      return FORM_FIELD_STORAGE_ABORT;
   }
   mg_snprintf(fud->conn,
               &truncated,
               path,
               pathlen - 1,
               "%s/%s",
               fud->destination_dir,
               filename);
   if (truncated) {
      mg_cry_internal(fud->conn, "%s: File path too long", __func__);
      return FORM_FIELD_STORAGE_ABORT;
   }
   return FORM_FIELD_STORAGE_STORE;
}


/* Helper function for deprecated mg_upload. */
static int
mg_upload_field_get(const char *key,
                    const char *value,
                    size_t value_size,
                    void *user_data)
{
   /* Function should never be called */
   (void)key;
   (void)value;
   (void)value_size;
   (void)user_data;

   return 0;
}


/* Helper function for deprecated mg_upload. */
static int
mg_upload_field_stored(const char *path, long long file_size, void *user_data)
{
   struct mg_upload_user_data *fud = (struct mg_upload_user_data *)user_data;
   (void)file_size;

   fud->num_uploaded_files++;
   fud->conn->phys_ctx->callbacks.upload(fud->conn, path);

   return 0;
}


/* Deprecated function mg_upload - use mg_handle_form_request instead. */
int
mg_upload(struct mg_connection *conn, const char *destination_dir)
{
   struct mg_upload_user_data fud = {conn, destination_dir, 0};
   struct mg_form_data_handler fdh = {mg_upload_field_found,
                                      mg_upload_field_get,
                                      mg_upload_field_stored,
                                      0};
   int ret;

   fdh.user_data = (void *)&fud;
   ret = mg_handle_form_request(conn, &fdh);

   if (ret < 0) {
      mg_cry_internal(conn, "%s: Error while parsing the request", __func__);
   }

   return fud.num_uploaded_files;
}
#endif


static int
get_first_ssl_listener_index(const struct mg_context *ctx)
{
   unsigned int i;
   int idx = -1;
   if (ctx) {
      for (i = 0; ((idx == -1) && (i < ctx->num_listening_sockets)); i++) {
         idx = ctx->listening_sockets[i].is_ssl ? ((int)(i)) : -1;
      }
   }
   return idx;
}


/* Return host (without port) */
/* Use mg_free to free the result */
static const char *
alloc_get_host(struct mg_connection *conn)
{
   char buf[1025];
   size_t buflen = sizeof(buf);
   const char *host_header = get_header(conn->request_info.http_headers,
                                        conn->request_info.num_headers,
                                        "Host");
   char *host;

   if (host_header != NULL) {
      char *pos;

      /* Create a local copy of the "Host" header, since it might be
       * modified here. */
      mg_strlcpy(buf, host_header, buflen);
      buf[buflen - 1] = '\0';
      host = buf;
      while (isspace(*host)) {
         host++;
      }

      /* If the "Host" is an IPv6 address, like [::1], parse until ]
       * is found. */
      if (*host == '[') {
         pos = strchr(host, ']');
         if (!pos) {
            /* Malformed hostname starts with '[', but no ']' found */
            DEBUG_TRACE("%s", "Host name format error '[' without ']'");
            return NULL;
         }
         /* terminate after ']' */
         pos[1] = 0;
      } else {
         /* Otherwise, a ':' separates hostname and port number */
         pos = strchr(host, ':');
         if (pos != NULL) {
            *pos = '\0';
         }
      }

      if (conn->ssl) {
         /* This is a HTTPS connection, maybe we have a hostname
          * from SNI (set in ssl_servername_callback). */
         const char *sslhost = conn->dom_ctx->config[AUTHENTICATION_DOMAIN];
         if (sslhost && (conn->dom_ctx != &(conn->phys_ctx->dd))) {
            /* We are not using the default domain */
            if (mg_strcasecmp(host, sslhost)) {
               /* Mismatch between SNI domain and HTTP domain */
               DEBUG_TRACE("Host mismatch: SNI: %s, HTTPS: %s",
                           sslhost,
                           host);
               return NULL;
            }
         }
         DEBUG_TRACE("HTTPS Host: %s", host);

      } else {
         struct mg_domain_context *dom = &(conn->phys_ctx->dd);
         while (dom) {
            if (!mg_strcasecmp(host, dom->config[AUTHENTICATION_DOMAIN])) {

               /* Found matching domain */
               DEBUG_TRACE("HTTP domain %s found",
                           dom->config[AUTHENTICATION_DOMAIN]);

               /* TODO: Check if this is a HTTP or HTTPS domain */
               conn->dom_ctx = dom;
               break;
            }
            dom = dom->next;
         }

         DEBUG_TRACE("HTTP Host: %s", host);
      }

   } else {
      sockaddr_to_string(buf, buflen, &conn->client.lsa);
      host = buf;

      DEBUG_TRACE("IP: %s", host);
   }

   return mg_strdup_ctx(host, conn->phys_ctx);
}


static void
redirect_to_https_port(struct mg_connection *conn, int ssl_index)
{
   char target_url[MG_BUF_LEN];
   int truncated = 0;

   conn->must_close = 1;

   /* Send host, port, uri and (if it exists) ?query_string */
   if (conn->host) {

      /* Use "308 Permanent Redirect" */
      int redirect_code = 308;

      /* Create target URL */
      mg_snprintf(
          conn,
          &truncated,
          target_url,
          sizeof(target_url),
          "https://%s:%d%s%s%s",

          conn->host,
#if defined(USE_IPV6)
          (conn->phys_ctx->listening_sockets[ssl_index].lsa.sa.sa_family
           == AF_INET6)
              ? (int)ntohs(conn->phys_ctx->listening_sockets[ssl_index]
                               .lsa.sin6.sin6_port)
              :
#endif
              (int)ntohs(conn->phys_ctx->listening_sockets[ssl_index]
                             .lsa.sin.sin_port),
          conn->request_info.local_uri,
          (conn->request_info.query_string == NULL) ? "" : "?",
          (conn->request_info.query_string == NULL)
              ? ""
              : conn->request_info.query_string);

      /* Check overflow in location buffer (will not occur if MG_BUF_LEN
       * is used as buffer size) */
      if (truncated) {
         mg_send_http_error(conn, 500, "%s", "Redirect URL too long");
         return;
      }

      /* Use redirect helper function */
      mg_send_http_redirect(conn, target_url, redirect_code);
   }
}


static void
handler_info_acquire(struct mg_handler_info *handler_info)
{
   pthread_mutex_lock(&handler_info->refcount_mutex);
   handler_info->refcount++;
   pthread_mutex_unlock(&handler_info->refcount_mutex);
}


static void
handler_info_release(struct mg_handler_info *handler_info)
{
   pthread_mutex_lock(&handler_info->refcount_mutex);
   handler_info->refcount--;
   pthread_cond_signal(&handler_info->refcount_cond);
   pthread_mutex_unlock(&handler_info->refcount_mutex);
}


static void
handler_info_wait_unused(struct mg_handler_info *handler_info)
{
   pthread_mutex_lock(&handler_info->refcount_mutex);
   while (handler_info->refcount) {
      pthread_cond_wait(&handler_info->refcount_cond,
                        &handler_info->refcount_mutex);
   }
   pthread_mutex_unlock(&handler_info->refcount_mutex);
}


static void
mg_set_handler_type(struct mg_context *phys_ctx,
                    struct mg_domain_context *dom_ctx,
                    const char *uri,
                    int handler_type,
                    int is_delete_request,
                    mg_request_handler handler,
                    struct mg_websocket_subprotocols *subprotocols,
                    mg_websocket_connect_handler connect_handler,
                    mg_websocket_ready_handler ready_handler,
                    mg_websocket_data_handler data_handler,
                    mg_websocket_close_handler close_handler,
                    mg_authorization_handler auth_handler,
                    void *cbdata)
{
   struct mg_handler_info *tmp_rh, **lastref;
   size_t urilen = strlen(uri);

   if (handler_type == WEBSOCKET_HANDLER) {
      DEBUG_ASSERT(handler == NULL);
      DEBUG_ASSERT(is_delete_request || connect_handler != NULL
                   || ready_handler != NULL || data_handler != NULL
                   || close_handler != NULL);

      DEBUG_ASSERT(auth_handler == NULL);
      if (handler != NULL) {
         return;
      }
      if (!is_delete_request && (connect_handler == NULL)
          && (ready_handler == NULL) && (data_handler == NULL)
          && (close_handler == NULL)) {
         return;
      }
      if (auth_handler != NULL) {
         return;
      }
   } else if (handler_type == REQUEST_HANDLER) {
      DEBUG_ASSERT(connect_handler == NULL && ready_handler == NULL
                   && data_handler == NULL && close_handler == NULL);
      DEBUG_ASSERT(is_delete_request || (handler != NULL));
      DEBUG_ASSERT(auth_handler == NULL);

      if ((connect_handler != NULL) || (ready_handler != NULL)
          || (data_handler != NULL) || (close_handler != NULL)) {
         return;
      }
      if (!is_delete_request && (handler == NULL)) {
         return;
      }
      if (auth_handler != NULL) {
         return;
      }
   } else { /* AUTH_HANDLER */
      DEBUG_ASSERT(handler == NULL);
      DEBUG_ASSERT(connect_handler == NULL && ready_handler == NULL
                   && data_handler == NULL && close_handler == NULL);
      DEBUG_ASSERT(auth_handler != NULL);
      if (handler != NULL) {
         return;
      }
      if ((connect_handler != NULL) || (ready_handler != NULL)
          || (data_handler != NULL) || (close_handler != NULL)) {
         return;
      }
      if (!is_delete_request && (auth_handler == NULL)) {
         return;
      }
   }

   if (!phys_ctx || !dom_ctx) {
      return;
   }

   mg_lock_context(phys_ctx);

   /* first try to find an existing handler */
   lastref = &(dom_ctx->handlers);
   for (tmp_rh = dom_ctx->handlers; tmp_rh != NULL; tmp_rh = tmp_rh->next) {
      if (tmp_rh->handler_type == handler_type) {
         if ((urilen == tmp_rh->uri_len) && !strcmp(tmp_rh->uri, uri)) {
            if (!is_delete_request) {
               /* update existing handler */
               if (handler_type == REQUEST_HANDLER) {
                  /* Wait for end of use before updating */
                  handler_info_wait_unused(tmp_rh);

                  /* Ok, the handler is no more use -> Update it */
                  tmp_rh->handler = handler;
               } else if (handler_type == WEBSOCKET_HANDLER) {
                  tmp_rh->subprotocols = subprotocols;
                  tmp_rh->connect_handler = connect_handler;
                  tmp_rh->ready_handler = ready_handler;
                  tmp_rh->data_handler = data_handler;
                  tmp_rh->close_handler = close_handler;
               } else { /* AUTH_HANDLER */
                  tmp_rh->auth_handler = auth_handler;
               }
               tmp_rh->cbdata = cbdata;
            } else {
               /* remove existing handler */
               if (handler_type == REQUEST_HANDLER) {
                  /* Wait for end of use before removing */
                  handler_info_wait_unused(tmp_rh);

                  /* Ok, the handler is no more used -> Destroy resources
                   */
                  pthread_cond_destroy(&tmp_rh->refcount_cond);
                  pthread_mutex_destroy(&tmp_rh->refcount_mutex);
               }
               *lastref = tmp_rh->next;
               mg_free(tmp_rh->uri);
               mg_free(tmp_rh);
            }
            mg_unlock_context(phys_ctx);
            return;
         }
      }
      lastref = &(tmp_rh->next);
   }

   if (is_delete_request) {
      /* no handler to set, this was a remove request to a non-existing
       * handler */
      mg_unlock_context(phys_ctx);
      return;
   }

   tmp_rh =
       (struct mg_handler_info *)mg_calloc_ctx(sizeof(struct mg_handler_info),
                                               1,
                                               phys_ctx);
   if (tmp_rh == NULL) {
      mg_unlock_context(phys_ctx);
      mg_cry_internal(fc(phys_ctx),
                      "%s",
                      "Cannot create new request handler struct, OOM");
      return;
   }
   tmp_rh->uri = mg_strdup_ctx(uri, phys_ctx);
   if (!tmp_rh->uri) {
      mg_unlock_context(phys_ctx);
      mg_free(tmp_rh);
      mg_cry_internal(fc(phys_ctx),
                      "%s",
                      "Cannot create new request handler struct, OOM");
      return;
   }
   tmp_rh->uri_len = urilen;
   if (handler_type == REQUEST_HANDLER) {
      /* Init refcount mutex and condition */
      if (0 != pthread_mutex_init(&tmp_rh->refcount_mutex, NULL)) {
         mg_unlock_context(phys_ctx);
         mg_free(tmp_rh);
         mg_cry_internal(fc(phys_ctx), "%s", "Cannot init refcount mutex");
         return;
      }
      if (0 != pthread_cond_init(&tmp_rh->refcount_cond, NULL)) {
         mg_unlock_context(phys_ctx);
         pthread_mutex_destroy(&tmp_rh->refcount_mutex);
         mg_free(tmp_rh);
         mg_cry_internal(fc(phys_ctx), "%s", "Cannot init refcount cond");
         return;
      }
      tmp_rh->refcount = 0;
      tmp_rh->handler = handler;
   } else if (handler_type == WEBSOCKET_HANDLER) {
      tmp_rh->subprotocols = subprotocols;
      tmp_rh->connect_handler = connect_handler;
      tmp_rh->ready_handler = ready_handler;
      tmp_rh->data_handler = data_handler;
      tmp_rh->close_handler = close_handler;
   } else { /* AUTH_HANDLER */
      tmp_rh->auth_handler = auth_handler;
   }
   tmp_rh->cbdata = cbdata;
   tmp_rh->handler_type = handler_type;
   tmp_rh->next = NULL;

   *lastref = tmp_rh;
   mg_unlock_context(phys_ctx);
}


void
mg_set_request_handler(struct mg_context *ctx,
                       const char *uri,
                       mg_request_handler handler,
                       void *cbdata)
{
   mg_set_handler_type(ctx,
                       &(ctx->dd),
                       uri,
                       REQUEST_HANDLER,
                       handler == NULL,
                       handler,
                       NULL,
                       NULL,
                       NULL,
                       NULL,
                       NULL,
                       NULL,
                       cbdata);
}


void
mg_set_websocket_handler(struct mg_context *ctx,
                         const char *uri,
                         mg_websocket_connect_handler connect_handler,
                         mg_websocket_ready_handler ready_handler,
                         mg_websocket_data_handler data_handler,
                         mg_websocket_close_handler close_handler,
                         void *cbdata)
{
   mg_set_websocket_handler_with_subprotocols(ctx,
                                              uri,
                                              NULL,
                                              connect_handler,
                                              ready_handler,
                                              data_handler,
                                              close_handler,
                                              cbdata);
}


void
mg_set_websocket_handler_with_subprotocols(
    struct mg_context *ctx,
    const char *uri,
    struct mg_websocket_subprotocols *subprotocols,
    mg_websocket_connect_handler connect_handler,
    mg_websocket_ready_handler ready_handler,
    mg_websocket_data_handler data_handler,
    mg_websocket_close_handler close_handler,
    void *cbdata)
{
   int is_delete_request = (connect_handler == NULL) && (ready_handler == NULL)
                           && (data_handler == NULL)
                           && (close_handler == NULL);
   mg_set_handler_type(ctx,
                       &(ctx->dd),
                       uri,
                       WEBSOCKET_HANDLER,
                       is_delete_request,
                       NULL,
                       subprotocols,
                       connect_handler,
                       ready_handler,
                       data_handler,
                       close_handler,
                       NULL,
                       cbdata);
}


void
mg_set_auth_handler(struct mg_context *ctx,
                    const char *uri,
                    mg_request_handler handler,
                    void *cbdata)
{
   mg_set_handler_type(ctx,
                       &(ctx->dd),
                       uri,
                       AUTH_HANDLER,
                       handler == NULL,
                       NULL,
                       NULL,
                       NULL,
                       NULL,
                       NULL,
                       NULL,
                       handler,
                       cbdata);
}


static int
get_request_handler(struct mg_connection *conn,
                    int handler_type,
                    mg_request_handler *handler,
                    struct mg_websocket_subprotocols **subprotocols,
                    mg_websocket_connect_handler *connect_handler,
                    mg_websocket_ready_handler *ready_handler,
                    mg_websocket_data_handler *data_handler,
                    mg_websocket_close_handler *close_handler,
                    mg_authorization_handler *auth_handler,
                    void **cbdata,
                    struct mg_handler_info **handler_info)
{
   const struct mg_request_info *request_info = mg_get_request_info(conn);
   if (request_info) {
      const char *uri = request_info->local_uri;
      size_t urilen = strlen(uri);
      struct mg_handler_info *tmp_rh;

      if (!conn || !conn->phys_ctx || !conn->dom_ctx) {
         return 0;
      }

      mg_lock_context(conn->phys_ctx);

      /* first try for an exact match */
      for (tmp_rh = conn->dom_ctx->handlers; tmp_rh != NULL;
           tmp_rh = tmp_rh->next) {
         if (tmp_rh->handler_type == handler_type) {
            if ((urilen == tmp_rh->uri_len) && !strcmp(tmp_rh->uri, uri)) {
               if (handler_type == WEBSOCKET_HANDLER) {
                  *subprotocols = tmp_rh->subprotocols;
                  *connect_handler = tmp_rh->connect_handler;
                  *ready_handler = tmp_rh->ready_handler;
                  *data_handler = tmp_rh->data_handler;
                  *close_handler = tmp_rh->close_handler;
               } else if (handler_type == REQUEST_HANDLER) {
                  *handler = tmp_rh->handler;
                  /* Acquire handler and give it back */
                  handler_info_acquire(tmp_rh);
                  *handler_info = tmp_rh;
               } else { /* AUTH_HANDLER */
                  *auth_handler = tmp_rh->auth_handler;
               }
               *cbdata = tmp_rh->cbdata;
               mg_unlock_context(conn->phys_ctx);
               return 1;
            }
         }
      }

      /* next try for a partial match, we will accept uri/something */
      for (tmp_rh = conn->dom_ctx->handlers; tmp_rh != NULL;
           tmp_rh = tmp_rh->next) {
         if (tmp_rh->handler_type == handler_type) {
            if ((tmp_rh->uri_len < urilen) && (uri[tmp_rh->uri_len] == '/')
                && (memcmp(tmp_rh->uri, uri, tmp_rh->uri_len) == 0)) {
               if (handler_type == WEBSOCKET_HANDLER) {
                  *subprotocols = tmp_rh->subprotocols;
                  *connect_handler = tmp_rh->connect_handler;
                  *ready_handler = tmp_rh->ready_handler;
                  *data_handler = tmp_rh->data_handler;
                  *close_handler = tmp_rh->close_handler;
               } else if (handler_type == REQUEST_HANDLER) {
                  *handler = tmp_rh->handler;
                  /* Acquire handler and give it back */
                  handler_info_acquire(tmp_rh);
                  *handler_info = tmp_rh;
               } else { /* AUTH_HANDLER */
                  *auth_handler = tmp_rh->auth_handler;
               }
               *cbdata = tmp_rh->cbdata;
               mg_unlock_context(conn->phys_ctx);
               return 1;
            }
         }
      }

      /* finally try for pattern match */
      for (tmp_rh = conn->dom_ctx->handlers; tmp_rh != NULL;
           tmp_rh = tmp_rh->next) {
         if (tmp_rh->handler_type == handler_type) {
            if (match_prefix(tmp_rh->uri, tmp_rh->uri_len, uri) > 0) {
               if (handler_type == WEBSOCKET_HANDLER) {
                  *subprotocols = tmp_rh->subprotocols;
                  *connect_handler = tmp_rh->connect_handler;
                  *ready_handler = tmp_rh->ready_handler;
                  *data_handler = tmp_rh->data_handler;
                  *close_handler = tmp_rh->close_handler;
               } else if (handler_type == REQUEST_HANDLER) {
                  *handler = tmp_rh->handler;
                  /* Acquire handler and give it back */
                  handler_info_acquire(tmp_rh);
                  *handler_info = tmp_rh;
               } else { /* AUTH_HANDLER */
                  *auth_handler = tmp_rh->auth_handler;
               }
               *cbdata = tmp_rh->cbdata;
               mg_unlock_context(conn->phys_ctx);
               return 1;
            }
         }
      }

      mg_unlock_context(conn->phys_ctx);
   }
   return 0; /* none found */
}


/* Check if the script file is in a path, allowed for script files.
 * This can be used if uploading files is possible not only for the server
 * admin, and the upload mechanism does not check the file extension.
 */
static int
is_in_script_path(const struct mg_connection *conn, const char *path)
{
   /* TODO (Feature): Add config value for allowed script path.
    * Default: All allowed. */
   (void)conn;
   (void)path;
   return 1;
}


#if defined(USE_WEBSOCKET) && defined(MG_LEGACY_INTERFACE)
static int
deprecated_websocket_connect_wrapper(const struct mg_connection *conn,
                                     void *cbdata)
{
   struct mg_callbacks *pcallbacks = (struct mg_callbacks *)cbdata;
   if (pcallbacks->websocket_connect) {
      return pcallbacks->websocket_connect(conn);
   }
   /* No handler set - assume "OK" */
   return 0;
}


static void
deprecated_websocket_ready_wrapper(struct mg_connection *conn, void *cbdata)
{
   struct mg_callbacks *pcallbacks = (struct mg_callbacks *)cbdata;
   if (pcallbacks->websocket_ready) {
      pcallbacks->websocket_ready(conn);
   }
}


static int
deprecated_websocket_data_wrapper(struct mg_connection *conn,
                                  int bits,
                                  char *data,
                                  size_t len,
                                  void *cbdata)
{
   struct mg_callbacks *pcallbacks = (struct mg_callbacks *)cbdata;
   if (pcallbacks->websocket_data) {
      return pcallbacks->websocket_data(conn, bits, data, len);
   }
   /* No handler set - assume "OK" */
   return 1;
}
#endif


/* This is the heart of the Civetweb's logic.
 * This function is called when the request is read, parsed and validated,
 * and Civetweb must decide what action to take: serve a file, or
 * a directory, or call embedded function, etcetera. */
static void
handle_request(struct mg_connection *conn)
{
   struct mg_request_info *ri = &conn->request_info;
   char path[PATH_MAX];
   int uri_len, ssl_index;
   int is_found = 0, is_script_resource = 0, is_websocket_request = 0,
       is_put_or_delete_request = 0, is_callback_resource = 0;
   int i;
   struct mg_file file = STRUCT_FILE_INITIALIZER;
   mg_request_handler callback_handler = NULL;
   struct mg_handler_info *handler_info = NULL;
   struct mg_websocket_subprotocols *subprotocols;
   mg_websocket_connect_handler ws_connect_handler = NULL;
   mg_websocket_ready_handler ws_ready_handler = NULL;
   mg_websocket_data_handler ws_data_handler = NULL;
   mg_websocket_close_handler ws_close_handler = NULL;
   void *callback_data = NULL;
   mg_authorization_handler auth_handler = NULL;
   void *auth_callback_data = NULL;
   int handler_type;
   time_t curtime = time(NULL);
   char date[64];

   path[0] = 0;

   /* 1. get the request url */
   /* 1.1. split into url and query string */
   if ((conn->request_info.query_string = strchr(ri->request_uri, '?'))
       != NULL) {
      *((char *)conn->request_info.query_string++) = '\0';
   }

   /* 1.2. do a https redirect, if required. Do not decode URIs yet. */
   if (!conn->client.is_ssl && conn->client.ssl_redir) {
      ssl_index = get_first_ssl_listener_index(conn->phys_ctx);
      if (ssl_index >= 0) {
         redirect_to_https_port(conn, ssl_index);
      } else {
         /* A http to https forward port has been specified,
          * but no https port to forward to. */
         mg_send_http_error(conn,
                            503,
                            "%s",
                            "Error: SSL forward not configured properly");
         mg_cry_internal(conn,
                         "%s",
                         "Can not redirect to SSL, no SSL port available");
      }
      return;
   }
   uri_len = (int)strlen(ri->local_uri);

   /* 1.3. decode url (if config says so) */
   if (should_decode_url(conn)) {
      mg_url_decode(
          ri->local_uri, uri_len, (char *)ri->local_uri, uri_len + 1, 0);
   }

   /* 1.4. clean URIs, so a path like allowed_dir/../forbidden_file is
    * not possible */
   remove_double_dots_and_double_slashes((char *)ri->local_uri);

   /* step 1. completed, the url is known now */
   uri_len = (int)strlen(ri->local_uri);
   DEBUG_TRACE("URL: %s", ri->local_uri);

   /* 2. if this ip has limited speed, set it for this connection */
   conn->throttle = set_throttle(conn->dom_ctx->config[THROTTLE],
                                 get_remote_ip(conn),
                                 ri->local_uri);

   /* 3. call a "handle everything" callback, if registered */
   if (conn->phys_ctx->callbacks.begin_request != NULL) {
      /* Note that since V1.7 the "begin_request" function is called
       * before an authorization check. If an authorization check is
       * required, use a request_handler instead. */
      i = conn->phys_ctx->callbacks.begin_request(conn);
      if (i > 0) {
         /* callback already processed the request. Store the
            return value as a status code for the access log. */
         conn->status_code = i;
         discard_unread_request_data(conn);
         return;
      } else if (i == 0) {
         /* civetweb should process the request */
      } else {
         /* unspecified - may change with the next version */
         return;
      }
   }

   /* request not yet handled by a handler or redirect, so the request
    * is processed here */

   /* 4. Check for CORS preflight requests and handle them (if configured).
    * https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS
    */
   if (!strcmp(ri->request_method, "OPTIONS")) {
      /* Send a response to CORS preflights only if
       * access_control_allow_methods is not NULL and not an empty string.
       * In this case, scripts can still handle CORS. */
      const char *cors_meth_cfg =
          conn->dom_ctx->config[ACCESS_CONTROL_ALLOW_METHODS];
      const char *cors_orig_cfg =
          conn->dom_ctx->config[ACCESS_CONTROL_ALLOW_ORIGIN];
      const char *cors_origin =
          get_header(ri->http_headers, ri->num_headers, "Origin");
      const char *cors_acrm = get_header(ri->http_headers,
                                         ri->num_headers,
                                         "Access-Control-Request-Method");

      /* Todo: check if cors_origin is in cors_orig_cfg.
       * Or, let the client check this. */

      if ((cors_meth_cfg != NULL) && (*cors_meth_cfg != 0)
          && (cors_orig_cfg != NULL) && (*cors_orig_cfg != 0)
          && (cors_origin != NULL) && (cors_acrm != NULL)) {
         /* This is a valid CORS preflight, and the server is configured
          * to
          * handle it automatically. */
         const char *cors_acrh =
             get_header(ri->http_headers,
                        ri->num_headers,
                        "Access-Control-Request-Headers");

         gmt_time_string(date, sizeof(date), &curtime);
         mg_printf(conn,
                   "HTTP/1.1 200 OK\r\n"
                   "Date: %s\r\n"
                   "Access-Control-Allow-Origin: %s\r\n"
                   "Access-Control-Allow-Methods: %s\r\n"
                   "Content-Length: 0\r\n"
                   "Connection: %s\r\n",
                   date,
                   cors_orig_cfg,
                   ((cors_meth_cfg[0] == '*') ? cors_acrm : cors_meth_cfg),
                   suggest_connection_header(conn));

         if (cors_acrh != NULL) {
            /* CORS request is asking for additional headers */
            const char *cors_hdr_cfg =
                conn->dom_ctx->config[ACCESS_CONTROL_ALLOW_HEADERS];

            if ((cors_hdr_cfg != NULL) && (*cors_hdr_cfg != 0)) {
               /* Allow only if access_control_allow_headers is
                * not NULL and not an empty string. If this
                * configuration is set to *, allow everything.
                * Otherwise this configuration must be a list
                * of allowed HTTP header names. */
               mg_printf(conn,
                         "Access-Control-Allow-Headers: %s\r\n",
                         ((cors_hdr_cfg[0] == '*') ? cors_acrh
                                                   : cors_hdr_cfg));
            }
         }
         mg_printf(conn, "Access-Control-Max-Age: 60\r\n");

         mg_printf(conn, "\r\n");
         return;
      }
   }

   /* 5. interpret the url to find out how the request must be handled
    */
   /* 5.1. first test, if the request targets the regular http(s)://
    * protocol namespace or the websocket ws(s):// protocol namespace.
    */
   is_websocket_request = is_websocket_protocol(conn);
#if defined(USE_WEBSOCKET)
   handler_type = is_websocket_request ? WEBSOCKET_HANDLER : REQUEST_HANDLER;
#else
   handler_type = REQUEST_HANDLER;
#endif /* defined(USE_WEBSOCKET) */
   /* 5.2. check if the request will be handled by a callback */
   if (get_request_handler(conn,
                           handler_type,
                           &callback_handler,
                           &subprotocols,
                           &ws_connect_handler,
                           &ws_ready_handler,
                           &ws_data_handler,
                           &ws_close_handler,
                           NULL,
                           &callback_data,
                           &handler_info)) {
      /* 5.2.1. A callback will handle this request. All requests
       * handled
       * by a callback have to be considered as requests to a script
       * resource. */
      is_callback_resource = 1;
      is_script_resource = 1;
      is_put_or_delete_request = is_put_or_delete_method(conn);
   } else {
   no_callback_resource:

      /* 5.2.2. No callback is responsible for this request. The URI
       * addresses a file based resource (static content or Lua/cgi
       * scripts in the file system). */
      is_callback_resource = 0;
      interpret_uri(conn,
                    path,
                    sizeof(path),
                    &file.stat,
                    &is_found,
                    &is_script_resource,
                    &is_websocket_request,
                    &is_put_or_delete_request);
   }

   /* 6. authorization check */
   /* 6.1. a custom authorization handler is installed */
   if (get_request_handler(conn,
                           AUTH_HANDLER,
                           NULL,
                           NULL,
                           NULL,
                           NULL,
                           NULL,
                           NULL,
                           &auth_handler,
                           &auth_callback_data,
                           NULL)) {
      if (!auth_handler(conn, auth_callback_data)) {
         return;
      }
   } else if (is_put_or_delete_request && !is_script_resource
              && !is_callback_resource) {
/* 6.2. this request is a PUT/DELETE to a real file */
/* 6.2.1. thus, the server must have real files */
#if defined(NO_FILES)
      if (1) {
#else
      if (conn->dom_ctx->config[DOCUMENT_ROOT] == NULL) {
#endif
         /* This server does not have any real files, thus the
          * PUT/DELETE methods are not valid. */
         mg_send_http_error(conn,
                            405,
                            "%s method not allowed",
                            conn->request_info.request_method);
         return;
      }

#if !defined(NO_FILES)
      /* 6.2.2. Check if put authorization for static files is
       * available.
       */
      if (!is_authorized_for_put(conn)) {
         send_authorization_request(conn, NULL);
         return;
      }
#endif

   } else {
      /* 6.3. This is either a OPTIONS, GET, HEAD or POST request,
       * or it is a PUT or DELETE request to a resource that does not
       * correspond to a file. Check authorization. */
      if (!check_authorization(conn, path)) {
         send_authorization_request(conn, NULL);
         return;
      }
   }

   /* request is authorized or does not need authorization */

   /* 7. check if there are request handlers for this uri */
   if (is_callback_resource) {
      if (!is_websocket_request) {
         i = callback_handler(conn, callback_data);

         /* Callback handler will not be used anymore. Release it */
         handler_info_release(handler_info);

         if (i > 0) {
            /* Do nothing, callback has served the request. Store
             * then return value as status code for the log and discard
             * all data from the client not used by the callback. */
            conn->status_code = i;
            discard_unread_request_data(conn);
         } else {
            /* The handler did NOT handle the request. */
            /* Some proper reactions would be:
             * a) close the connections without sending anything
             * b) send a 404 not found
             * c) try if there is a file matching the URI
             * It would be possible to do a, b or c in the callback
             * implementation, and return 1 - we cannot do anything
             * here, that is not possible in the callback.
             *
             * TODO: What would be the best reaction here?
             * (Note: The reaction may change, if there is a better
             *idea.)
             */

            /* For the moment, use option c: We look for a proper file,
             * but since a file request is not always a script resource,
             * the authorization check might be different. */
            interpret_uri(conn,
                          path,
                          sizeof(path),
                          &file.stat,
                          &is_found,
                          &is_script_resource,
                          &is_websocket_request,
                          &is_put_or_delete_request);
            callback_handler = NULL;

            /* Here we are at a dead end:
             * According to URI matching, a callback should be
             * responsible for handling the request,
             * we called it, but the callback declared itself
             * not responsible.
             * We use a goto here, to get out of this dead end,
             * and continue with the default handling.
             * A goto here is simpler and better to understand
             * than some curious loop. */
            goto no_callback_resource;
         }
      } else {
#if defined(USE_WEBSOCKET)
         handle_websocket_request(conn,
                                  path,
                                  is_callback_resource,
                                  subprotocols,
                                  ws_connect_handler,
                                  ws_ready_handler,
                                  ws_data_handler,
                                  ws_close_handler,
                                  callback_data);
#endif
      }
      return;
   }

/* 8. handle websocket requests */
#if defined(USE_WEBSOCKET)
   if (is_websocket_request) {
      if (is_script_resource) {

         if (is_in_script_path(conn, path)) {
            /* Websocket Lua script */
            handle_websocket_request(conn,
                                     path,
                                     0 /* Lua Script */,
                                     NULL,
                                     NULL,
                                     NULL,
                                     NULL,
                                     NULL,
                                     conn->phys_ctx->user_data);
         } else {
            /* Script was in an illegal path */
            mg_send_http_error(conn, 403, "%s", "Forbidden");
         }
      } else {
#if defined(MG_LEGACY_INTERFACE)
         handle_websocket_request(
             conn,
             path,
             !is_script_resource /* could be deprecated global callback */,
             NULL,
             deprecated_websocket_connect_wrapper,
             deprecated_websocket_ready_wrapper,
             deprecated_websocket_data_wrapper,
             NULL,
             conn->phys_ctx->user_data);
#else
         mg_send_http_error(conn, 404, "%s", "Not found");
#endif
      }
      return;
   } else
#endif

#if defined(NO_FILES)
      /* 9a. In case the server uses only callbacks, this uri is
       * unknown.
       * Then, all request handling ends here. */
      mg_send_http_error(conn, 404, "%s", "Not Found");

#else
   /* 9b. This request is either for a static file or resource handled
    * by a script file. Thus, a DOCUMENT_ROOT must exist. */
   if (conn->dom_ctx->config[DOCUMENT_ROOT] == NULL) {
      mg_send_http_error(conn, 404, "%s", "Not Found");
      return;
   }

   /* 10. Request is handled by a script */
   if (is_script_resource) {
      handle_file_based_request(conn, path, &file);
      return;
   }

   /* 11. Handle put/delete/mkcol requests */
   if (is_put_or_delete_request) {
      /* 11.1. PUT method */
      if (!strcmp(ri->request_method, "PUT")) {
         put_file(conn, path);
         return;
      }
      /* 11.2. DELETE method */
      if (!strcmp(ri->request_method, "DELETE")) {
         delete_file(conn, path);
         return;
      }
      /* 11.3. MKCOL method */
      if (!strcmp(ri->request_method, "MKCOL")) {
         mkcol(conn, path);
         return;
      }
      /* 11.4. PATCH method
       * This method is not supported for static resources,
       * only for scripts (Lua, CGI) and callbacks. */
      mg_send_http_error(conn,
                         405,
                         "%s method not allowed",
                         conn->request_info.request_method);
      return;
   }

   /* 11. File does not exist, or it was configured that it should be
    * hidden */
   if (!is_found || (must_hide_file(conn, path))) {
      mg_send_http_error(conn, 404, "%s", "Not found");
      return;
   }

   /* 12. Directory uris should end with a slash */
   if (file.stat.is_directory && (uri_len > 0)
       && (ri->local_uri[uri_len - 1] != '/')) {
      gmt_time_string(date, sizeof(date), &curtime);
      mg_printf(conn,
                "HTTP/1.1 301 Moved Permanently\r\n"
                "Location: %s/\r\n"
                "Date: %s\r\n"
                /* "Cache-Control: private\r\n" (= default) */
                "Content-Length: 0\r\n"
                "Connection: %s\r\n",
                ri->request_uri,
                date,
                suggest_connection_header(conn));
      send_additional_header(conn);
      mg_printf(conn, "\r\n");
      return;
   }

   /* 13. Handle other methods than GET/HEAD */
   /* 13.1. Handle PROPFIND */
   if (!strcmp(ri->request_method, "PROPFIND")) {
      handle_propfind(conn, path, &file.stat);
      return;
   }
   /* 13.2. Handle OPTIONS for files */
   if (!strcmp(ri->request_method, "OPTIONS")) {
      /* This standard handler is only used for real files.
       * Scripts should support the OPTIONS method themselves, to allow a
       * maximum flexibility.
       * Lua and CGI scripts may fully support CORS this way (including
       * preflights). */
      send_options(conn);
      return;
   }
   /* 13.3. everything but GET and HEAD (e.g. POST) */
   if ((0 != strcmp(ri->request_method, "GET"))
       && (0 != strcmp(ri->request_method, "HEAD"))) {
      mg_send_http_error(conn,
                         405,
                         "%s method not allowed",
                         conn->request_info.request_method);
      return;
   }

   /* 14. directories */
   if (file.stat.is_directory) {
      /* Substitute files have already been handled above. */
      /* Here we can either generate and send a directory listing,
       * or send an "access denied" error. */
      if (!mg_strcasecmp(conn->dom_ctx->config[ENABLE_DIRECTORY_LISTING],
                         "yes")) {
         handle_directory_request(conn, path);
      } else {
         mg_send_http_error(conn,
                            403,
                            "%s",
                            "Error: Directory listing denied");
      }
      return;
   }

   /* 15. read a normal file with GET or HEAD */
   handle_file_based_request(conn, path, &file);
#endif /* !defined(NO_FILES) */
}


static void
handle_file_based_request(struct mg_connection *conn,
                          const char *path,
                          struct mg_file *file)
{
   if (!conn || !conn->dom_ctx) {
      return;
   }

   if (0) {
#if defined(USE_LUA)
   } else if (match_prefix(
                  conn->dom_ctx->config[LUA_SERVER_PAGE_EXTENSIONS],
                  strlen(conn->dom_ctx->config[LUA_SERVER_PAGE_EXTENSIONS]),
                  path)
              > 0) {
      if (is_in_script_path(conn, path)) {
         /* Lua server page: an SSI like page containing mostly plain
          * html
          * code
          * plus some tags with server generated contents. */
         handle_lsp_request(conn, path, file, NULL);
      } else {
         /* Script was in an illegal path */
         mg_send_http_error(conn, 403, "%s", "Forbidden");
      }

   } else if (match_prefix(conn->dom_ctx->config[LUA_SCRIPT_EXTENSIONS],
                           strlen(
                               conn->dom_ctx->config[LUA_SCRIPT_EXTENSIONS]),
                           path)
              > 0) {
      if (is_in_script_path(conn, path)) {
         /* Lua in-server module script: a CGI like script used to
          * generate
          * the
          * entire reply. */
         mg_exec_lua_script(conn, path, NULL);
      } else {
         /* Script was in an illegal path */
         mg_send_http_error(conn, 403, "%s", "Forbidden");
      }
#endif
#if defined(USE_DUKTAPE)
   } else if (match_prefix(
                  conn->dom_ctx->config[DUKTAPE_SCRIPT_EXTENSIONS],
                  strlen(conn->dom_ctx->config[DUKTAPE_SCRIPT_EXTENSIONS]),
                  path)
              > 0) {
      if (is_in_script_path(conn, path)) {
         /* Call duktape to generate the page */
         mg_exec_duktape_script(conn, path);
      } else {
         /* Script was in an illegal path */
         mg_send_http_error(conn, 403, "%s", "Forbidden");
      }
#endif
#if !defined(NO_CGI)
   } else if (match_prefix(conn->dom_ctx->config[CGI_EXTENSIONS],
                           strlen(conn->dom_ctx->config[CGI_EXTENSIONS]),
                           path)
              > 0) {
      if (is_in_script_path(conn, path)) {
         /* CGI scripts may support all HTTP methods */
         handle_cgi_request(conn, path);
      } else {
         /* Script was in an illegal path */
         mg_send_http_error(conn, 403, "%s", "Forbidden");
      }
#endif /* !NO_CGI */
   } else if (match_prefix(conn->dom_ctx->config[SSI_EXTENSIONS],
                           strlen(conn->dom_ctx->config[SSI_EXTENSIONS]),
                           path)
              > 0) {
      if (is_in_script_path(conn, path)) {
         handle_ssi_file_request(conn, path, file);
      } else {
         /* Script was in an illegal path */
         mg_send_http_error(conn, 403, "%s", "Forbidden");
      }
#if !defined(NO_CACHING)
   } else if ((!conn->in_error_handler)
              && is_not_modified(conn, &file->stat)) {
      /* Send 304 "Not Modified" - this must not send any body data */
      handle_not_modified_static_file_request(conn, file);
#endif /* !NO_CACHING */
   } else {
      handle_static_file_request(conn, path, file, NULL, NULL);
   }
}


static void
close_all_listening_sockets(struct mg_context *ctx)
{
   unsigned int i;
   if (!ctx) {
      return;
   }

   for (i = 0; i < ctx->num_listening_sockets; i++) {
      closesocket(ctx->listening_sockets[i].sock);
      ctx->listening_sockets[i].sock = INVALID_SOCKET;
   }
   mg_free(ctx->listening_sockets);
   ctx->listening_sockets = NULL;
   mg_free(ctx->listening_socket_fds);
   ctx->listening_socket_fds = NULL;
}


/* Valid listening port specification is: [ip_address:]port[s]
 * Examples for IPv4: 80, 443s, 127.0.0.1:3128, 192.0.2.3:8080s
 * Examples for IPv6: [::]:80, [::1]:80,
 *   [2001:0db8:7654:3210:FEDC:BA98:7654:3210]:443s
 *   see https://tools.ietf.org/html/rfc3513#section-2.2
 * In order to bind to both, IPv4 and IPv6, you can either add
 * both ports using 8080,[::]:8080, or the short form +8080.
 * Both forms differ in detail: 8080,[::]:8080 create two sockets,
 * one only accepting IPv4 the other only IPv6. +8080 creates
 * one socket accepting IPv4 and IPv6. Depending on the IPv6
 * environment, they might work differently, or might not work
 * at all - it must be tested what options work best in the
 * relevant network environment.
 */
static int
parse_port_string(const struct vec *vec, struct socket *so, int *ip_version)
{
   unsigned int a, b, c, d, port;
   int ch, len;
   const char *cb;
#if defined(USE_IPV6)
   char buf[100] = {0};
#endif

   /* MacOS needs that. If we do not zero it, subsequent bind() will fail.
    * Also, all-zeroes in the socket address means binding to all addresses
    * for both IPv4 and IPv6 (INADDR_ANY and IN6ADDR_ANY_INIT). */
   memset(so, 0, sizeof(*so));
   so->lsa.sin.sin_family = AF_INET;
   *ip_version = 0;

   /* Initialize port and len as invalid. */
   port = 0;
   len = 0;

   /* Test for different ways to format this string */
   if (sscanf(vec->ptr, "%u.%u.%u.%u:%u%n", &a, &b, &c, &d, &port, &len)
       == 5) {
      /* Bind to a specific IPv4 address, e.g. 192.168.1.5:8080 */
      so->lsa.sin.sin_addr.s_addr =
          htonl((a << 24) | (b << 16) | (c << 8) | d);
      so->lsa.sin.sin_port = htons((uint16_t)port);
      *ip_version = 4;

#if defined(USE_IPV6)
   } else if (sscanf(vec->ptr, "[%49[^]]]:%u%n", buf, &port, &len) == 2
              && mg_inet_pton(
                     AF_INET6, buf, &so->lsa.sin6, sizeof(so->lsa.sin6))) {
      /* IPv6 address, examples: see above */
      /* so->lsa.sin6.sin6_family = AF_INET6; already set by mg_inet_pton
       */
      so->lsa.sin6.sin6_port = htons((uint16_t)port);
      *ip_version = 6;
#endif

   } else if ((vec->ptr[0] == '+')
              && (sscanf(vec->ptr + 1, "%u%n", &port, &len) == 1)) {

      /* Port is specified with a +, bind to IPv6 and IPv4, INADDR_ANY */
      /* Add 1 to len for the + character we skipped before */
      len++;

#if defined(USE_IPV6)
      /* Set socket family to IPv6, do not use IPV6_V6ONLY */
      so->lsa.sin6.sin6_family = AF_INET6;
      so->lsa.sin6.sin6_port = htons((uint16_t)port);
      *ip_version = 4 + 6;
#else
      /* Bind to IPv4 only, since IPv6 is not built in. */
      so->lsa.sin.sin_port = htons((uint16_t)port);
      *ip_version = 4;
#endif

   } else if (sscanf(vec->ptr, "%u%n", &port, &len) == 1) {
      /* If only port is specified, bind to IPv4, INADDR_ANY */
      so->lsa.sin.sin_port = htons((uint16_t)port);
      *ip_version = 4;

   } else if ((cb = strchr(vec->ptr, ':')) != NULL) {
      /* String could be a hostname. This check algotithm
       * will only work for RFC 952 compliant hostnames,
       * starting with a letter, containing only letters,
       * digits and hyphen ('-'). Newer specs may allow
       * more, but this is not guaranteed here, since it
       * may interfere with rules for port option lists. */

      /* According to RFC 1035, hostnames are restricted to 255 characters
       * in total (63 between two dots). */
      char hostname[256];
      size_t hostnlen = (size_t)(cb - vec->ptr);

      if (hostnlen >= sizeof(hostname)) {
         /* This would be invalid in any case */
         *ip_version = 0;
         return 0;
      }

      memcpy(hostname, vec->ptr, hostnlen);
      hostname[hostnlen] = 0;

      if (mg_inet_pton(
              AF_INET, vec->ptr, &so->lsa.sin, sizeof(so->lsa.sin))) {
         if (sscanf(cb + 1, "%u%n", &port, &len) == 1) {
            *ip_version = 4;
            so->lsa.sin.sin_family = AF_INET;
            so->lsa.sin.sin_port = htons((uint16_t)port);
            len += (int)(hostnlen + 1);
         } else {
            port = 0;
            len = 0;
         }
#if defined(USE_IPV6)
      } else if (mg_inet_pton(AF_INET6,
                              vec->ptr,
                              &so->lsa.sin6,
                              sizeof(so->lsa.sin6))) {
         if (sscanf(cb + 1, "%u%n", &port, &len) == 1) {
            *ip_version = 6;
            so->lsa.sin6.sin6_family = AF_INET6;
            so->lsa.sin.sin_port = htons((uint16_t)port);
            len += (int)(hostnlen + 1);
         } else {
            port = 0;
            len = 0;
         }
#endif
      }


   } else {
      /* Parsing failure. */
   }

   /* sscanf and the option splitting code ensure the following condition
    */
   if ((len < 0) && ((unsigned)len > (unsigned)vec->len)) {
      *ip_version = 0;
      return 0;
   }
   ch = vec->ptr[len]; /* Next character after the port number */
   so->is_ssl = (ch == 's');
   so->ssl_redir = (ch == 'r');

   /* Make sure the port is valid and vector ends with 's', 'r' or ',' */
   if (is_valid_port(port)
       && ((ch == '\0') || (ch == 's') || (ch == 'r') || (ch == ','))) {
      return 1;
   }

   /* Reset ip_version to 0 if there is an error */
   *ip_version = 0;
   return 0;
}


/* Is there any SSL port in use? */
static int
is_ssl_port_used(const char *ports)
{
   if (ports) {
      /* There are several different allowed syntax variants:
       * - "80" for a single port using every network interface
       * - "localhost:80" for a single port using only localhost
       * - "80,localhost:8080" for two ports, one bound to localhost
       * - "80,127.0.0.1:8084,[::1]:8086" for three ports, one bound
       *   to IPv4 localhost, one to IPv6 localhost
       * - "+80" use port 80 for IPv4 and IPv6
       * - "+80r,+443s" port 80 (HTTP) is a redirect to port 443 (HTTPS),
       *   for both: IPv4 and IPv4
       * - "+443s,localhost:8080" port 443 (HTTPS) for every interface,
       *   additionally port 8080 bound to localhost connections
       *
       * If we just look for 's' anywhere in the string, "localhost:80"
       * will be detected as SSL (false positive).
       * Looking for 's' after a digit may cause false positives in
       * "my24service:8080".
       * Looking from 's' backward if there are only ':' and numbers
       * before will not work for "24service:8080" (non SSL, port 8080)
       * or "24s" (SSL, port 24).
       *
       * Remark: Initially hostnames were not allowed to start with a
       * digit (according to RFC 952), this was allowed later (RFC 1123,
       * Section 2.1).
       *
       * To get this correct, the entire string must be parsed as a whole,
       * reading it as a list element for element and parsing with an
       * algorithm equivalent to parse_port_string.
       *
       * In fact, we use local interface names here, not arbitrary hostnames,
       * so in most cases the only name will be "localhost".
       *
       * So, for now, we use this simple algorithm, that may still return
       * a false positive in bizarre cases.
       */
      int i;
      int portslen = (int)strlen(ports);
      char prevIsNumber = 0;

      for (i = 0; i < portslen; i++) {
         if (prevIsNumber && (ports[i] == 's' || ports[i] == 'r')) {
            return 1;
         }
         if (ports[i] >= '0' && ports[i] <= '9') {
            prevIsNumber = 1;
         } else {
            prevIsNumber = 0;
         }
      }
   }
   return 0;
}


static int
set_ports_option(struct mg_context *phys_ctx)
{
   const char *list;
   int on = 1;
#if defined(USE_IPV6)
   int off = 0;
#endif
   struct vec vec;
   struct socket so, *ptr;

   struct pollfd *pfd;
   union usa usa;
   socklen_t len;
   int ip_version;

   int portsTotal = 0;
   int portsOk = 0;

   if (!phys_ctx) {
      return 0;
   }

   memset(&so, 0, sizeof(so));
   memset(&usa, 0, sizeof(usa));
   len = sizeof(usa);
   list = phys_ctx->dd.config[LISTENING_PORTS];

   while ((list = next_option(list, &vec, NULL)) != NULL) {

      portsTotal++;

      if (!parse_port_string(&vec, &so, &ip_version)) {
         mg_cry_internal(
             fc(phys_ctx),
             "%.*s: invalid port spec (entry %i). Expecting list of: %s",
             (int)vec.len,
             vec.ptr,
             portsTotal,
             "[IP_ADDRESS:]PORT[s|r]");
         continue;
      }

#if !defined(NO_SSL)
      if (so.is_ssl && phys_ctx->dd.ssl_ctx == NULL) {

         mg_cry_internal(fc(phys_ctx),
                         "Cannot add SSL socket (entry %i)",
                         portsTotal);
         continue;
      }
#endif

      if ((so.sock = socket(so.lsa.sa.sa_family, SOCK_STREAM, 6))
          == INVALID_SOCKET) {

         mg_cry_internal(fc(phys_ctx),
                         "cannot create socket (entry %i)",
                         portsTotal);
         continue;
      }

#if defined(_WIN32)
      /* Windows SO_REUSEADDR lets many procs binds to a
       * socket, SO_EXCLUSIVEADDRUSE makes the bind fail
       * if someone already has the socket -- DTL */
      /* NOTE: If SO_EXCLUSIVEADDRUSE is used,
       * Windows might need a few seconds before
       * the same port can be used again in the
       * same process, so a short Sleep may be
       * required between mg_stop and mg_start.
       */
      if (setsockopt(so.sock,
                     SOL_SOCKET,
                     SO_EXCLUSIVEADDRUSE,
                     (SOCK_OPT_TYPE)&on,
                     sizeof(on))
          != 0) {

         /* Set reuse option, but don't abort on errors. */
         mg_cry_internal(
             fc(phys_ctx),
             "cannot set socket option SO_EXCLUSIVEADDRUSE (entry %i)",
             portsTotal);
      }
#else
      if (setsockopt(so.sock,
                     SOL_SOCKET,
                     SO_REUSEADDR,
                     (SOCK_OPT_TYPE)&on,
                     sizeof(on))
          != 0) {

         /* Set reuse option, but don't abort on errors. */
         mg_cry_internal(fc(phys_ctx),
                         "cannot set socket option SO_REUSEADDR (entry %i)",
                         portsTotal);
      }
#endif

      if (ip_version > 4) {
/* Could be 6 for IPv6 onlyor 10 (4+6) for IPv4+IPv6 */
#if defined(USE_IPV6)
         if (ip_version > 6) {
            if (so.lsa.sa.sa_family == AF_INET6
                && setsockopt(so.sock,
                              IPPROTO_IPV6,
                              IPV6_V6ONLY,
                              (void *)&off,
                              sizeof(off))
                       != 0) {

               /* Set IPv6 only option, but don't abort on errors. */
               mg_cry_internal(
                   fc(phys_ctx),
                   "cannot set socket option IPV6_V6ONLY=off (entry %i)",
                   portsTotal);
            }
         } else {
            if (so.lsa.sa.sa_family == AF_INET6
                && setsockopt(so.sock,
                              IPPROTO_IPV6,
                              IPV6_V6ONLY,
                              (void *)&on,
                              sizeof(on))
                       != 0) {

               /* Set IPv6 only option, but don't abort on errors. */
               mg_cry_internal(
                   fc(phys_ctx),
                   "cannot set socket option IPV6_V6ONLY=on (entry %i)",
                   portsTotal);
            }
         }
#else
         mg_cry_internal(fc(phys_ctx), "%s", "IPv6 not available");
         closesocket(so.sock);
         so.sock = INVALID_SOCKET;
         continue;
#endif
      }

      if (so.lsa.sa.sa_family == AF_INET) {

         len = sizeof(so.lsa.sin);
         if (bind(so.sock, &so.lsa.sa, len) != 0) {
            mg_cry_internal(fc(phys_ctx),
                            "cannot bind to %.*s: %d (%s)",
                            (int)vec.len,
                            vec.ptr,
                            (int)ERRNO,
                            strerror(errno));
            closesocket(so.sock);
            so.sock = INVALID_SOCKET;
            continue;
         }
      }
#if defined(USE_IPV6)
      else if (so.lsa.sa.sa_family == AF_INET6) {

         len = sizeof(so.lsa.sin6);
         if (bind(so.sock, &so.lsa.sa, len) != 0) {
            mg_cry_internal(fc(phys_ctx),
                            "cannot bind to IPv6 %.*s: %d (%s)",
                            (int)vec.len,
                            vec.ptr,
                            (int)ERRNO,
                            strerror(errno));
            closesocket(so.sock);
            so.sock = INVALID_SOCKET;
            continue;
         }
      }
#endif
      else {
         mg_cry_internal(
             fc(phys_ctx),
             "cannot bind: address family not supported (entry %i)",
             portsTotal);
         closesocket(so.sock);
         so.sock = INVALID_SOCKET;
         continue;
      }

      if (listen(so.sock, SOMAXCONN) != 0) {

         mg_cry_internal(fc(phys_ctx),
                         "cannot listen to %.*s: %d (%s)",
                         (int)vec.len,
                         vec.ptr,
                         (int)ERRNO,
                         strerror(errno));
         closesocket(so.sock);
         so.sock = INVALID_SOCKET;
         continue;
      }

      if ((getsockname(so.sock, &(usa.sa), &len) != 0)
          || (usa.sa.sa_family != so.lsa.sa.sa_family)) {

         int err = (int)ERRNO;
         mg_cry_internal(fc(phys_ctx),
                         "call to getsockname failed %.*s: %d (%s)",
                         (int)vec.len,
                         vec.ptr,
                         err,
                         strerror(errno));
         closesocket(so.sock);
         so.sock = INVALID_SOCKET;
         continue;
      }

/* Update lsa port in case of random free ports */
#if defined(USE_IPV6)
      if (so.lsa.sa.sa_family == AF_INET6) {
         so.lsa.sin6.sin6_port = usa.sin6.sin6_port;
      } else
#endif
      {
         so.lsa.sin.sin_port = usa.sin.sin_port;
      }

      if ((ptr = (struct socket *)
               mg_realloc_ctx(phys_ctx->listening_sockets,
                              (phys_ctx->num_listening_sockets + 1)
                                  * sizeof(phys_ctx->listening_sockets[0]),
                              phys_ctx))
          == NULL) {

         mg_cry_internal(fc(phys_ctx), "%s", "Out of memory");
         closesocket(so.sock);
         so.sock = INVALID_SOCKET;
         continue;
      }

      if ((pfd = (struct pollfd *)
               mg_realloc_ctx(phys_ctx->listening_socket_fds,
                              (phys_ctx->num_listening_sockets + 1)
                                  * sizeof(phys_ctx->listening_socket_fds[0]),
                              phys_ctx))
          == NULL) {

         mg_cry_internal(fc(phys_ctx), "%s", "Out of memory");
         closesocket(so.sock);
         so.sock = INVALID_SOCKET;
         mg_free(ptr);
         continue;
      }

      set_close_on_exec(so.sock, fc(phys_ctx));
      phys_ctx->listening_sockets = ptr;
      phys_ctx->listening_sockets[phys_ctx->num_listening_sockets] = so;
      phys_ctx->listening_socket_fds = pfd;
      phys_ctx->num_listening_sockets++;
      portsOk++;
   }

   if (portsOk != portsTotal) {
      close_all_listening_sockets(phys_ctx);
      portsOk = 0;
   }

   return portsOk;
}


static const char *
header_val(const struct mg_connection *conn, const char *header)
{
   const char *header_value;

   if ((header_value = mg_get_header(conn, header)) == NULL) {
      return "-";
   } else {
      return header_value;
   }
}


#if defined(MG_EXTERNAL_FUNCTION_log_access)
static void log_access(const struct mg_connection *conn);
#include "external_log_access.inl"
#else

static void
log_access(const struct mg_connection *conn)
{
   const struct mg_request_info *ri;
   struct mg_file fi;
   char date[64], src_addr[IP_ADDR_STR_LEN];
   struct tm *tm;

   const char *referer;
   const char *user_agent;

   char buf[4096];

   if (!conn || !conn->dom_ctx) {
      return;
   }

   if (conn->dom_ctx->config[ACCESS_LOG_FILE] != NULL) {
      if (mg_fopen(conn,
                   conn->dom_ctx->config[ACCESS_LOG_FILE],
                   MG_FOPEN_MODE_APPEND,
                   &fi)
          == 0) {
         fi.access.fp = NULL;
      }
   } else {
      fi.access.fp = NULL;
   }

   /* Log is written to a file and/or a callback. If both are not set,
    * executing the rest of the function is pointless. */
   if ((fi.access.fp == NULL)
       && (conn->phys_ctx->callbacks.log_access == NULL)) {
      return;
   }

   tm = localtime(&conn->conn_birth_time);
   if (tm != NULL) {
      strftime(date, sizeof(date), "%d/%b/%Y:%H:%M:%S %z", tm);
   } else {
      mg_strlcpy(date, "01/Jan/1970:00:00:00 +0000", sizeof(date));
      date[sizeof(date) - 1] = '\0';
   }

   ri = &conn->request_info;

   sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);
   referer = header_val(conn, "Referer");
   user_agent = header_val(conn, "User-Agent");

   mg_snprintf(conn,
               NULL, /* Ignore truncation in access log */
               buf,
               sizeof(buf),
               "%s - %s [%s] \"%s %s%s%s HTTP/%s\" %d %" INT64_FMT " %s %s",
               src_addr,
               (ri->remote_user == NULL) ? "-" : ri->remote_user,
               date,
               ri->request_method ? ri->request_method : "-",
               ri->request_uri ? ri->request_uri : "-",
               ri->query_string ? "?" : "",
               ri->query_string ? ri->query_string : "",
               ri->http_version,
               conn->status_code,
               conn->num_bytes_sent,
               referer,
               user_agent);

   if (conn->phys_ctx->callbacks.log_access) {
      conn->phys_ctx->callbacks.log_access(conn, buf);
   }

   if (fi.access.fp) {
      int ok = 1;
      flockfile(fi.access.fp);
      if (fprintf(fi.access.fp, "%s\n", buf) < 1) {
         ok = 0;
      }
      if (fflush(fi.access.fp) != 0) {
         ok = 0;
      }
      funlockfile(fi.access.fp);
      if (mg_fclose(&fi.access) != 0) {
         ok = 0;
      }
      if (!ok) {
         mg_cry_internal(conn,
                         "Error writing log file %s",
                         conn->dom_ctx->config[ACCESS_LOG_FILE]);
      }
   }
}

#endif /* Externally provided function */


/* Verify given socket address against the ACL.
 * Return -1 if ACL is malformed, 0 if address is disallowed, 1 if allowed.
 */
static int
check_acl(struct mg_context *phys_ctx, uint32_t remote_ip)
{
   int allowed, flag;
   uint32_t net, mask;
   struct vec vec;

   if (phys_ctx) {
      const char *list = phys_ctx->dd.config[ACCESS_CONTROL_LIST];

      /* If any ACL is set, deny by default */
      allowed = (list == NULL) ? '+' : '-';

      while ((list = next_option(list, &vec, NULL)) != NULL) {
         flag = vec.ptr[0];
         if ((flag != '+' && flag != '-')
             || (parse_net(&vec.ptr[1], &net, &mask) == 0)) {
            mg_cry_internal(fc(phys_ctx),
                            "%s: subnet must be [+|-]x.x.x.x[/x]",
                            __func__);
            return -1;
         }

         if (net == (remote_ip & mask)) {
            allowed = flag;
         }
      }

      return allowed == '+';
   }
   return -1;
}


#if !defined(_WIN32)
static int
set_uid_option(struct mg_context *phys_ctx)
{
   int success = 0;

   if (phys_ctx) {
      /* We are currently running as curr_uid. */
      const uid_t curr_uid = getuid();
      /* If set, we want to run as run_as_user. */
      const char *run_as_user = phys_ctx->dd.config[RUN_AS_USER];
      const struct passwd *to_pw = NULL;

      if (run_as_user != NULL && (to_pw = getpwnam(run_as_user)) == NULL) {
         /* run_as_user does not exist on the system. We can't proceed
          * further. */
         mg_cry_internal(fc(phys_ctx),
                         "%s: unknown user [%s]",
                         __func__,
                         run_as_user);
      } else if (run_as_user == NULL || curr_uid == to_pw->pw_uid) {
         /* There was either no request to change user, or we're already
          * running as run_as_user. Nothing else to do.
          */
         success = 1;
      } else {
         /* Valid change request.  */
         if (setgid(to_pw->pw_gid) == -1) {
            mg_cry_internal(fc(phys_ctx),
                            "%s: setgid(%s): %s",
                            __func__,
                            run_as_user,
                            strerror(errno));
         } else if (setgroups(0, NULL) == -1) {
            mg_cry_internal(fc(phys_ctx),
                            "%s: setgroups(): %s",
                            __func__,
                            strerror(errno));
         } else if (setuid(to_pw->pw_uid) == -1) {
            mg_cry_internal(fc(phys_ctx),
                            "%s: setuid(%s): %s",
                            __func__,
                            run_as_user,
                            strerror(errno));
         } else {
            success = 1;
         }
      }
   }

   return success;
}
#endif /* !_WIN32 */


static void
tls_dtor(void *key)
{
   struct mg_workerTLS *tls = (struct mg_workerTLS *)key;
   /* key == pthread_getspecific(sTlsKey); */

   if (tls) {
      if (tls->is_master == 2) {
         tls->is_master = -3; /* Mark memory as dead */
         mg_free(tls);
      }
   }
   pthread_setspecific(sTlsKey, NULL);
}


#if !defined(NO_SSL)

static int ssl_use_pem_file(struct mg_context *phys_ctx,
                            struct mg_domain_context *dom_ctx,
                            const char *pem,
                            const char *chain);
static const char *ssl_error(void);


static int
refresh_trust(struct mg_connection *conn)
{
   static int reload_lock = 0;
   static long int data_check = 0;
   volatile int *p_reload_lock = (volatile int *)&reload_lock;

   struct stat cert_buf;
   long int t;
   const char *pem;
   const char *chain;
   int should_verify_peer;

   if ((pem = conn->dom_ctx->config[SSL_CERTIFICATE]) == NULL) {
      /* If peem is NULL and conn->phys_ctx->callbacks.init_ssl is not,
       * refresh_trust still can not work. */
      return 0;
   }
   chain = conn->dom_ctx->config[SSL_CERTIFICATE_CHAIN];
   if (chain == NULL) {
      /* pem is not NULL here */
      chain = pem;
   }
   if (*chain == 0) {
      chain = NULL;
   }

   t = data_check;
   if (stat(pem, &cert_buf) != -1) {
      t = (long int)cert_buf.st_mtime;
   }

   if (data_check != t) {
      data_check = t;

      should_verify_peer = 0;
      if (conn->dom_ctx->config[SSL_DO_VERIFY_PEER] != NULL) {
         if (mg_strcasecmp(conn->dom_ctx->config[SSL_DO_VERIFY_PEER], "yes")
             == 0) {
            should_verify_peer = 1;
         } else if (mg_strcasecmp(conn->dom_ctx->config[SSL_DO_VERIFY_PEER],
                                  "optional")
                    == 0) {
            should_verify_peer = 1;
         }
      }

      if (should_verify_peer) {
         char *ca_path = conn->dom_ctx->config[SSL_CA_PATH];
         char *ca_file = conn->dom_ctx->config[SSL_CA_FILE];
         if (SSL_CTX_load_verify_locations(conn->dom_ctx->ssl_ctx,
                                           ca_file,
                                           ca_path)
             != 1) {
            mg_cry_internal(
                fc(conn->phys_ctx),
                "SSL_CTX_load_verify_locations error: %s "
                "ssl_verify_peer requires setting "
                "either ssl_ca_path or ssl_ca_file. Is any of them "
                "present in "
                "the .conf file?",
                ssl_error());
            return 0;
         }
      }

      if (1 == mg_atomic_inc(p_reload_lock)) {
         if (ssl_use_pem_file(conn->phys_ctx, conn->dom_ctx, pem, chain)
             == 0) {
            return 0;
         }
         *p_reload_lock = 0;
      }
   }
   /* lock while cert is reloading */
   while (*p_reload_lock) {
      sleep(1);
   }

   return 1;
}

#if defined(OPENSSL_API_1_1)
#else
static pthread_mutex_t *ssl_mutexes;
#endif /* OPENSSL_API_1_1 */

static int
sslize(struct mg_connection *conn,
       SSL_CTX *s,
       int (*func)(SSL *),
       volatile int *stop_server,
       const struct mg_client_options *client_options)
{
   int ret, err;
   int short_trust;
   unsigned i;

   if (!conn) {
      return 0;
   }

   short_trust =
       (conn->dom_ctx->config[SSL_SHORT_TRUST] != NULL)
       && (mg_strcasecmp(conn->dom_ctx->config[SSL_SHORT_TRUST], "yes") == 0);

   if (short_trust) {
      int trust_ret = refresh_trust(conn);
      if (!trust_ret) {
         return trust_ret;
      }
   }

   conn->ssl = SSL_new(s);
   if (conn->ssl == NULL) {
      return 0;
   }
   SSL_set_app_data(conn->ssl, (char *)conn);

   ret = SSL_set_fd(conn->ssl, conn->client.sock);
   if (ret != 1) {
      err = SSL_get_error(conn->ssl, ret);
      mg_cry_internal(conn, "SSL error %i, destroying SSL context", err);
      SSL_free(conn->ssl);
      conn->ssl = NULL;
      OPENSSL_REMOVE_THREAD_STATE();
      return 0;
   }

   if (client_options) {
      if (client_options->host_name) {
         SSL_set_tlsext_host_name(conn->ssl, client_options->host_name);
      }
   }

   /* SSL functions may fail and require to be called again:
    * see https://www.openssl.org/docs/manmaster/ssl/SSL_get_error.html
    * Here "func" could be SSL_connect or SSL_accept. */
   for (i = 16; i <= 1024; i *= 2) {
      ret = func(conn->ssl);
      if (ret != 1) {
         err = SSL_get_error(conn->ssl, ret);
         if ((err == SSL_ERROR_WANT_CONNECT)
             || (err == SSL_ERROR_WANT_ACCEPT)
             || (err == SSL_ERROR_WANT_READ) || (err == SSL_ERROR_WANT_WRITE)
             || (err == SSL_ERROR_WANT_X509_LOOKUP)) {
            /* Need to retry the function call "later".
             * See https://linux.die.net/man/3/ssl_get_error
             * This is typical for non-blocking sockets. */
            if (*stop_server) {
               /* Don't wait if the server is going to be stopped. */
               break;
            }
            mg_sleep(i);

         } else if (err == SSL_ERROR_SYSCALL) {
            /* This is an IO error. Look at errno. */
            err = errno;
            mg_cry_internal(conn, "SSL syscall error %i", err);
            break;

         } else {
            /* This is an SSL specific error, e.g. SSL_ERROR_SSL */
            mg_cry_internal(conn, "sslize error: %s", ssl_error());
            break;
         }

      } else {
         /* success */
         break;
      }
   }

   if (ret != 1) {
      SSL_free(conn->ssl);
      conn->ssl = NULL;
      OPENSSL_REMOVE_THREAD_STATE();
      return 0;
   }

   return 1;
}


/* Return OpenSSL error message (from CRYPTO lib) */
static const char *
ssl_error(void)
{
   unsigned long err;
   err = ERR_get_error();
   return ((err == 0) ? "" : ERR_error_string(err, NULL));
}


static int
hexdump2string(void *mem, int memlen, char *buf, int buflen)
{
   int i;
   const char hexdigit[] = "0123456789abcdef";

   if ((memlen <= 0) || (buflen <= 0)) {
      return 0;
   }
   if (buflen < (3 * memlen)) {
      return 0;
   }

   for (i = 0; i < memlen; i++) {
      if (i > 0) {
         buf[3 * i - 1] = ' ';
      }
      buf[3 * i] = hexdigit[(((uint8_t *)mem)[i] >> 4) & 0xF];
      buf[3 * i + 1] = hexdigit[((uint8_t *)mem)[i] & 0xF];
   }
   buf[3 * memlen - 1] = 0;

   return 1;
}


static void
ssl_get_client_cert_info(struct mg_connection *conn)
{
   X509 *cert = SSL_get_peer_certificate(conn->ssl);
   if (cert) {
      char str_subject[1024];
      char str_issuer[1024];
      char str_finger[1024];
      unsigned char buf[256];
      char *str_serial = NULL;
      unsigned int ulen;
      int ilen;
      unsigned char *tmp_buf;
      unsigned char *tmp_p;

      /* Handle to algorithm used for fingerprint */
      const EVP_MD *digest = EVP_get_digestbyname("sha1");

      /* Get Subject and issuer */
      X509_NAME *subj = X509_get_subject_name(cert);
      X509_NAME *iss = X509_get_issuer_name(cert);

      /* Get serial number */
      ASN1_INTEGER *serial = X509_get_serialNumber(cert);

      /* Translate serial number to a hex string */
      BIGNUM *serial_bn = ASN1_INTEGER_to_BN(serial, NULL);
      str_serial = BN_bn2hex(serial_bn);
      BN_free(serial_bn);

      /* Translate subject and issuer to a string */
      (void)X509_NAME_oneline(subj, str_subject, (int)sizeof(str_subject));
      (void)X509_NAME_oneline(iss, str_issuer, (int)sizeof(str_issuer));

      /* Calculate SHA1 fingerprint and store as a hex string */
      ulen = 0;

      /* ASN1_digest is deprecated. Do the calculation manually,
       * using EVP_Digest. */
      ilen = i2d_X509(cert, NULL);
      tmp_buf = (ilen > 0)
                    ? (unsigned char *)mg_malloc_ctx((unsigned)ilen + 1,
                                                     conn->phys_ctx)
                    : NULL;
      if (tmp_buf) {
         tmp_p = tmp_buf;
         (void)i2d_X509(cert, &tmp_p);
         if (!EVP_Digest(
                 tmp_buf, (unsigned)ilen, buf, &ulen, digest, NULL)) {
            ulen = 0;
         }
         mg_free(tmp_buf);
      }

      if (!hexdump2string(
              buf, (int)ulen, str_finger, (int)sizeof(str_finger))) {
         *str_finger = 0;
      }

      conn->request_info.client_cert = (struct mg_client_cert *)
          mg_malloc_ctx(sizeof(struct mg_client_cert), conn->phys_ctx);
      if (conn->request_info.client_cert) {
         conn->request_info.client_cert->peer_cert = (void *)cert;
         conn->request_info.client_cert->subject =
             mg_strdup_ctx(str_subject, conn->phys_ctx);
         conn->request_info.client_cert->issuer =
             mg_strdup_ctx(str_issuer, conn->phys_ctx);
         conn->request_info.client_cert->serial =
             mg_strdup_ctx(str_serial, conn->phys_ctx);
         conn->request_info.client_cert->finger =
             mg_strdup_ctx(str_finger, conn->phys_ctx);
      } else {
         mg_cry_internal(conn,
                         "%s",
                         "Out of memory: Cannot allocate memory for client "
                         "certificate");
      }

      /* Strings returned from bn_bn2hex must be freed using OPENSSL_free,
       * see https://linux.die.net/man/3/bn_bn2hex */
      OPENSSL_free(str_serial);
   }
}


#if defined(OPENSSL_API_1_1)
#else
static void
ssl_locking_callback(int mode, int mutex_num, const char *file, int line)
{
   (void)line;
   (void)file;

   if (mode & 1) {
      /* 1 is CRYPTO_LOCK */
      (void)pthread_mutex_lock(&ssl_mutexes[mutex_num]);
   } else {
      (void)pthread_mutex_unlock(&ssl_mutexes[mutex_num]);
   }
}
#endif /* OPENSSL_API_1_1 */


#if !defined(NO_SSL_DL)
static void *
load_dll(char *ebuf, size_t ebuf_len, const char *dll_name, struct ssl_func *sw)
{
   union {
      void *p;
      void (*fp)(void);
   } u;
   void *dll_handle;
   struct ssl_func *fp;
   int ok;
   int truncated = 0;

   if ((dll_handle = dlopen(dll_name, RTLD_LAZY)) == NULL) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s: cannot load %s",
                  __func__,
                  dll_name);
      return NULL;
   }

   ok = 1;
   for (fp = sw; fp->name != NULL; fp++) {
#if defined(_WIN32)
      /* GetProcAddress() returns pointer to function */
      u.fp = (void (*)(void))dlsym(dll_handle, fp->name);
#else
      /* dlsym() on UNIX returns void *. ISO C forbids casts of data
       * pointers to function pointers. We need to use a union to make a
       * cast. */
      u.p = dlsym(dll_handle, fp->name);
#endif /* _WIN32 */
      if (u.fp == NULL) {
         if (ok) {
            mg_snprintf(NULL,
                        &truncated,
                        ebuf,
                        ebuf_len,
                        "%s: %s: cannot find %s",
                        __func__,
                        dll_name,
                        fp->name);
            ok = 0;
         } else {
            size_t cur_len = strlen(ebuf);
            if (!truncated) {
               mg_snprintf(NULL,
                           &truncated,
                           ebuf + cur_len,
                           ebuf_len - cur_len - 3,
                           ", %s",
                           fp->name);
               if (truncated) {
                  /* If truncated, add "..." */
                  strcat(ebuf, "...");
               }
            }
         }
         /* Debug:
          * printf("Missing function: %s\n", fp->name); */
      } else {
         fp->ptr = u.fp;
      }
   }

   if (!ok) {
      (void)dlclose(dll_handle);
      return NULL;
   }

   return dll_handle;
}


static void *ssllib_dll_handle;    /* Store the ssl library handle. */
static void *cryptolib_dll_handle; /* Store the crypto library handle. */

#endif /* NO_SSL_DL */


#if defined(SSL_ALREADY_INITIALIZED)
static int cryptolib_users = 1; /* Reference counter for crypto library. */
#else
static int cryptolib_users = 0; /* Reference counter for crypto library. */
#endif


static int
initialize_ssl(char *ebuf, size_t ebuf_len)
{
#if defined(OPENSSL_API_1_1)
   if (ebuf_len > 0) {
      ebuf[0] = 0;
   }

#if !defined(NO_SSL_DL)
   if (!cryptolib_dll_handle) {
      cryptolib_dll_handle = load_dll(ebuf, ebuf_len, CRYPTO_LIB, crypto_sw);
      if (!cryptolib_dll_handle) {
         mg_snprintf(NULL,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "%s: error loading library %s",
                     __func__,
                     CRYPTO_LIB);
         DEBUG_TRACE("%s", ebuf);
         return 0;
      }
   }
#endif /* NO_SSL_DL */

   if (mg_atomic_inc(&cryptolib_users) > 1) {
      return 1;
   }

#else /* not OPENSSL_API_1_1 */
   int i, num_locks;
   size_t size;

   if (ebuf_len > 0) {
      ebuf[0] = 0;
   }

#if !defined(NO_SSL_DL)
   if (!cryptolib_dll_handle) {
      cryptolib_dll_handle = load_dll(ebuf, ebuf_len, CRYPTO_LIB, crypto_sw);
      if (!cryptolib_dll_handle) {
         mg_snprintf(NULL,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "%s: error loading library %s",
                     __func__,
                     CRYPTO_LIB);
         DEBUG_TRACE("%s", ebuf);
         return 0;
      }
   }
#endif /* NO_SSL_DL */

   if (mg_atomic_inc(&cryptolib_users) > 1) {
      return 1;
   }

   /* Initialize locking callbacks, needed for thread safety.
    * http://www.openssl.org/support/faq.html#PROG1
    */
   num_locks = CRYPTO_num_locks();
   if (num_locks < 0) {
      num_locks = 0;
   }
   size = sizeof(pthread_mutex_t) * ((size_t)(num_locks));

   /* allocate mutex array, if required */
   if (num_locks == 0) {
      /* No mutex array required */
      ssl_mutexes = NULL;
   } else {
      /* Mutex array required - allocate it */
      ssl_mutexes = (pthread_mutex_t *)mg_malloc(size);

      /* Check OOM */
      if (ssl_mutexes == NULL) {
         mg_snprintf(NULL,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "%s: cannot allocate mutexes: %s",
                     __func__,
                     ssl_error());
         DEBUG_TRACE("%s", ebuf);
         return 0;
      }

      /* initialize mutex array */
      for (i = 0; i < num_locks; i++) {
         if (0 != pthread_mutex_init(&ssl_mutexes[i], &pthread_mutex_attr)) {
            mg_snprintf(NULL,
                        NULL, /* No truncation check for ebuf */
                        ebuf,
                        ebuf_len,
                        "%s: error initializing mutex %i of %i",
                        __func__,
                        i,
                        num_locks);
            DEBUG_TRACE("%s", ebuf);
            mg_free(ssl_mutexes);
            return 0;
         }
      }
   }

   CRYPTO_set_locking_callback(&ssl_locking_callback);
   CRYPTO_set_id_callback(&mg_current_thread_id);
#endif /* OPENSSL_API_1_1 */

#if !defined(NO_SSL_DL)
   if (!ssllib_dll_handle) {
      ssllib_dll_handle = load_dll(ebuf, ebuf_len, SSL_LIB, ssl_sw);
      if (!ssllib_dll_handle) {
#if !defined(OPENSSL_API_1_1)
         mg_free(ssl_mutexes);
#endif
         DEBUG_TRACE("%s", ebuf);
         return 0;
      }
   }
#endif /* NO_SSL_DL */

#if defined(OPENSSL_API_1_1)
   /* Initialize SSL library */
   OPENSSL_init_ssl(0, NULL);
   OPENSSL_init_ssl(OPENSSL_INIT_LOAD_SSL_STRINGS
                        | OPENSSL_INIT_LOAD_CRYPTO_STRINGS,
                    NULL);
#else
   /* Initialize SSL library */
   SSL_library_init();
   SSL_load_error_strings();
#endif

   return 1;
}


static int
ssl_use_pem_file(struct mg_context *phys_ctx,
                 struct mg_domain_context *dom_ctx,
                 const char *pem,
                 const char *chain)
{
   if (SSL_CTX_use_certificate_file(dom_ctx->ssl_ctx, pem, 1) == 0) {
      mg_cry_internal(fc(phys_ctx),
                      "%s: cannot open certificate file %s: %s",
                      __func__,
                      pem,
                      ssl_error());
      return 0;
   }

   /* could use SSL_CTX_set_default_passwd_cb_userdata */
   if (SSL_CTX_use_PrivateKey_file(dom_ctx->ssl_ctx, pem, 1) == 0) {
      mg_cry_internal(fc(phys_ctx),
                      "%s: cannot open private key file %s: %s",
                      __func__,
                      pem,
                      ssl_error());
      return 0;
   }

   if (SSL_CTX_check_private_key(dom_ctx->ssl_ctx) == 0) {
      mg_cry_internal(fc(phys_ctx),
                      "%s: certificate and private key do not match: %s",
                      __func__,
                      pem);
      return 0;
   }

   /* In contrast to OpenSSL, wolfSSL does not support certificate
    * chain files that contain private keys and certificates in
    * SSL_CTX_use_certificate_chain_file.
    * The CivetWeb-Server used pem-Files that contained both information.
    * In order to make wolfSSL work, it is split in two files.
    * One file that contains key and certificate used by the server and
    * an optional chain file for the ssl stack.
    */
   if (chain) {
      if (SSL_CTX_use_certificate_chain_file(dom_ctx->ssl_ctx, chain) == 0) {
         mg_cry_internal(fc(phys_ctx),
                         "%s: cannot use certificate chain file %s: %s",
                         __func__,
                         pem,
                         ssl_error());
         return 0;
      }
   }
   return 1;
}


#if defined(OPENSSL_API_1_1)
static unsigned long
ssl_get_protocol(int version_id)
{
   long unsigned ret = (long unsigned)SSL_OP_ALL;
   if (version_id > 0)
      ret |= SSL_OP_NO_SSLv2;
   if (version_id > 1)
      ret |= SSL_OP_NO_SSLv3;
   if (version_id > 2)
      ret |= SSL_OP_NO_TLSv1;
   if (version_id > 3)
      ret |= SSL_OP_NO_TLSv1_1;
   return ret;
}
#else
static long
ssl_get_protocol(int version_id)
{
   long ret = (long)SSL_OP_ALL;
   if (version_id > 0)
      ret |= SSL_OP_NO_SSLv2;
   if (version_id > 1)
      ret |= SSL_OP_NO_SSLv3;
   if (version_id > 2)
      ret |= SSL_OP_NO_TLSv1;
   if (version_id > 3)
      ret |= SSL_OP_NO_TLSv1_1;
   return ret;
}
#endif /* OPENSSL_API_1_1 */


/* SSL callback documentation:
 * https://www.openssl.org/docs/man1.1.0/ssl/SSL_set_info_callback.html
 * https://wiki.openssl.org/index.php/Manual:SSL_CTX_set_info_callback(3)
 * https://linux.die.net/man/3/ssl_set_info_callback */
/* Note: There is no "const" for the first argument in the documentation
 * examples, however some (maybe most, but not all) headers of OpenSSL versions
 * / OpenSSL compatibility layers have it. Having a different definition will
 * cause a warning in C and an error in C++. Use "const SSL *", while
 * automatical conversion from "SSL *" works for all compilers, but not other
 * way around */
static void
ssl_info_callback(const SSL *ssl, int what, int ret)
{
   (void)ret;

   if (what & SSL_CB_HANDSHAKE_START) {
      SSL_get_app_data(ssl);
   }
   if (what & SSL_CB_HANDSHAKE_DONE) {
      /* TODO: check for openSSL 1.1 */
      //#define SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS 0x0001
      // ssl->s3->flags |= SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS;
   }
}


static int
ssl_servername_callback(SSL *ssl, int *ad, void *arg)
{
   struct mg_context *ctx = (struct mg_context *)arg;
   struct mg_domain_context *dom =
       (struct mg_domain_context *)ctx ? &(ctx->dd) : NULL;

#if defined(GCC_DIAGNOSTIC)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wcast-align"
#endif /* defined(GCC_DIAGNOSTIC) */

   /* We used an aligned pointer in SSL_set_app_data */
   struct mg_connection *conn = (struct mg_connection *)SSL_get_app_data(ssl);

#if defined(GCC_DIAGNOSTIC)
#pragma GCC diagnostic pop
#endif /* defined(GCC_DIAGNOSTIC) */

   const char *servername = SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);

   (void)ad;

   if ((ctx == NULL) || (conn->phys_ctx == ctx)) {
      DEBUG_TRACE("%s", "internal error - assertion failed");
      return SSL_TLSEXT_ERR_NOACK;
   }

   /* Old clients (Win XP) will not support SNI. Then, there
    * is no server name available in the request - we can
    * only work with the default certificate.
    * Multiple HTTPS hosts on one IP+port are only possible
    * with a certificate containing all alternative names.
    */
   if ((servername == NULL) || (*servername == 0)) {
      DEBUG_TRACE("%s", "SSL connection not supporting SNI");
      conn->dom_ctx = &(ctx->dd);
      SSL_set_SSL_CTX(ssl, conn->dom_ctx->ssl_ctx);
      return SSL_TLSEXT_ERR_NOACK;
   }

   DEBUG_TRACE("TLS connection to host %s", servername);

   while (dom) {
      if (!mg_strcasecmp(servername, dom->config[AUTHENTICATION_DOMAIN])) {

         /* Found matching domain */
         DEBUG_TRACE("TLS domain %s found",
                     dom->config[AUTHENTICATION_DOMAIN]);
         SSL_set_SSL_CTX(ssl, dom->ssl_ctx);
         conn->dom_ctx = dom;
         return SSL_TLSEXT_ERR_OK;
      }
      dom = dom->next;
   }

   /* Default domain */
   DEBUG_TRACE("TLS default domain %s used",
               ctx->dd.config[AUTHENTICATION_DOMAIN]);
   conn->dom_ctx = &(ctx->dd);
   SSL_set_SSL_CTX(ssl, conn->dom_ctx->ssl_ctx);
   return SSL_TLSEXT_ERR_OK;
}


/* Setup SSL CTX as required by CivetWeb */
static int
init_ssl_ctx_impl(struct mg_context *phys_ctx,
                  struct mg_domain_context *dom_ctx,
                  const char *pem,
                  const char *chain)
{
   int callback_ret;
   int should_verify_peer;
   int peer_certificate_optional;
   const char *ca_path;
   const char *ca_file;
   int use_default_verify_paths;
   int verify_depth;
   struct timespec now_mt;
   md5_byte_t ssl_context_id[16];
   md5_state_t md5state;
   int protocol_ver;

#if defined(OPENSSL_API_1_1)
   if ((dom_ctx->ssl_ctx = SSL_CTX_new(TLS_server_method())) == NULL) {
      mg_cry_internal(fc(phys_ctx),
                      "SSL_CTX_new (server) error: %s",
                      ssl_error());
      return 0;
   }
#else
   if ((dom_ctx->ssl_ctx = SSL_CTX_new(SSLv23_server_method())) == NULL) {
      mg_cry_internal(fc(phys_ctx),
                      "SSL_CTX_new (server) error: %s",
                      ssl_error());
      return 0;
   }
#endif /* OPENSSL_API_1_1 */

   SSL_CTX_clear_options(dom_ctx->ssl_ctx,
                         SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3 | SSL_OP_NO_TLSv1
                             | SSL_OP_NO_TLSv1_1);
   protocol_ver = atoi(dom_ctx->config[SSL_PROTOCOL_VERSION]);
   SSL_CTX_set_options(dom_ctx->ssl_ctx, ssl_get_protocol(protocol_ver));
   SSL_CTX_set_options(dom_ctx->ssl_ctx, SSL_OP_SINGLE_DH_USE);
   SSL_CTX_set_options(dom_ctx->ssl_ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
   SSL_CTX_set_options(dom_ctx->ssl_ctx,
                       SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION);
   SSL_CTX_set_options(dom_ctx->ssl_ctx, SSL_OP_NO_COMPRESSION);
#if !defined(NO_SSL_DL)
   SSL_CTX_set_ecdh_auto(dom_ctx->ssl_ctx, 1);
#endif /* NO_SSL_DL */

   /* In SSL documentation examples callback defined without const specifier
    * 'void (*)(SSL *, int, int)'   See:
    * https://www.openssl.org/docs/man1.0.2/ssl/ssl.html
    * https://www.openssl.org/docs/man1.1.0/ssl/ssl.html
    * But in the source code const SSL is used:
    * 'void (*)(const SSL *, int, int)' See:
    * https://github.com/openssl/openssl/blob/1d97c8435171a7af575f73c526d79e1ef0ee5960/ssl/ssl.h#L1173
    * Problem about wrong documentation described, but not resolved:
    * https://bugs.launchpad.net/ubuntu/+source/openssl/+bug/1147526
    * Wrong const cast ignored on C or can be suppressed by compiler flags.
    * But when compiled with modern C++ compiler, correct const should be
    * provided
    */
   SSL_CTX_set_info_callback(dom_ctx->ssl_ctx, ssl_info_callback);

   SSL_CTX_set_tlsext_servername_callback(dom_ctx->ssl_ctx,
                                          ssl_servername_callback);
   SSL_CTX_set_tlsext_servername_arg(dom_ctx->ssl_ctx, phys_ctx);

   /* If a callback has been specified, call it. */
   callback_ret = (phys_ctx->callbacks.init_ssl == NULL)
                      ? 0
                      : (phys_ctx->callbacks.init_ssl(dom_ctx->ssl_ctx,
                                                      phys_ctx->user_data));

   /* If callback returns 0, civetweb sets up the SSL certificate.
    * If it returns 1, civetweb assumes the calback already did this.
    * If it returns -1, initializing ssl fails. */
   if (callback_ret < 0) {
      mg_cry_internal(fc(phys_ctx),
                      "SSL callback returned error: %i",
                      callback_ret);
      return 0;
   }
   if (callback_ret > 0) {
      /* Callback did everything. */
      return 1;
   }

   /* Use some combination of start time, domain and port as a SSL
    * context ID. This should be unique on the current machine. */
   md5_init(&md5state);
   clock_gettime(CLOCK_MONOTONIC, &now_mt);
   md5_append(&md5state, (const md5_byte_t *)&now_mt, sizeof(now_mt));
   md5_append(&md5state,
              (const md5_byte_t *)phys_ctx->dd.config[LISTENING_PORTS],
              strlen(phys_ctx->dd.config[LISTENING_PORTS]));
   md5_append(&md5state,
              (const md5_byte_t *)dom_ctx->config[AUTHENTICATION_DOMAIN],
              strlen(dom_ctx->config[AUTHENTICATION_DOMAIN]));
   md5_append(&md5state, (const md5_byte_t *)phys_ctx, sizeof(*phys_ctx));
   md5_append(&md5state, (const md5_byte_t *)dom_ctx, sizeof(*dom_ctx));
   md5_finish(&md5state, ssl_context_id);

   SSL_CTX_set_session_id_context(dom_ctx->ssl_ctx,
                                  (unsigned char *)ssl_context_id,
                                  sizeof(ssl_context_id));

   if (pem != NULL) {
      if (!ssl_use_pem_file(phys_ctx, dom_ctx, pem, chain)) {
         return 0;
      }
   }

   /* Should we support client certificates? */
   /* Default is "no". */
   should_verify_peer = 0;
   peer_certificate_optional = 0;
   if (dom_ctx->config[SSL_DO_VERIFY_PEER] != NULL) {
      if (mg_strcasecmp(dom_ctx->config[SSL_DO_VERIFY_PEER], "yes") == 0) {
         /* Yes, they are mandatory */
         should_verify_peer = 1;
         peer_certificate_optional = 0;
      } else if (mg_strcasecmp(dom_ctx->config[SSL_DO_VERIFY_PEER],
                               "optional")
                 == 0) {
         /* Yes, they are optional */
         should_verify_peer = 1;
         peer_certificate_optional = 1;
      }
   }

   use_default_verify_paths =
       (dom_ctx->config[SSL_DEFAULT_VERIFY_PATHS] != NULL)
       && (mg_strcasecmp(dom_ctx->config[SSL_DEFAULT_VERIFY_PATHS], "yes")
           == 0);

   if (should_verify_peer) {
      ca_path = dom_ctx->config[SSL_CA_PATH];
      ca_file = dom_ctx->config[SSL_CA_FILE];
      if (SSL_CTX_load_verify_locations(dom_ctx->ssl_ctx, ca_file, ca_path)
          != 1) {
         mg_cry_internal(fc(phys_ctx),
                         "SSL_CTX_load_verify_locations error: %s "
                         "ssl_verify_peer requires setting "
                         "either ssl_ca_path or ssl_ca_file. "
                         "Is any of them present in the "
                         ".conf file?",
                         ssl_error());
         return 0;
      }

      if (peer_certificate_optional) {
         SSL_CTX_set_verify(dom_ctx->ssl_ctx, SSL_VERIFY_PEER, NULL);
      } else {
         SSL_CTX_set_verify(dom_ctx->ssl_ctx,
                            SSL_VERIFY_PEER
                                | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
                            NULL);
      }

      if (use_default_verify_paths
          && (SSL_CTX_set_default_verify_paths(dom_ctx->ssl_ctx) != 1)) {
         mg_cry_internal(fc(phys_ctx),
                         "SSL_CTX_set_default_verify_paths error: %s",
                         ssl_error());
         return 0;
      }

      if (dom_ctx->config[SSL_VERIFY_DEPTH]) {
         verify_depth = atoi(dom_ctx->config[SSL_VERIFY_DEPTH]);
         SSL_CTX_set_verify_depth(dom_ctx->ssl_ctx, verify_depth);
      }
   }

   if (dom_ctx->config[SSL_CIPHER_LIST] != NULL) {
      if (SSL_CTX_set_cipher_list(dom_ctx->ssl_ctx,
                                  dom_ctx->config[SSL_CIPHER_LIST])
          != 1) {
         mg_cry_internal(fc(phys_ctx),
                         "SSL_CTX_set_cipher_list error: %s",
                         ssl_error());
      }
   }

   return 1;
}


/* Check if SSL is required.
 * If so, dynamically load SSL library
 * and set up ctx->ssl_ctx pointer. */
static int
init_ssl_ctx(struct mg_context *phys_ctx, struct mg_domain_context *dom_ctx)
{
   void *ssl_ctx = 0;
   int callback_ret;
   const char *pem;
   const char *chain;
   char ebuf[128];

   if (!phys_ctx) {
      return 0;
   }

   if (!dom_ctx) {
      dom_ctx = &(phys_ctx->dd);
   }

   if (!is_ssl_port_used(dom_ctx->config[LISTENING_PORTS])) {
      /* No SSL port is set. No need to setup SSL. */
      return 1;
   }

   /* Check for external SSL_CTX */
   callback_ret =
       (phys_ctx->callbacks.external_ssl_ctx == NULL)
           ? 0
           : (phys_ctx->callbacks.external_ssl_ctx(&ssl_ctx,
                                                   phys_ctx->user_data));

   if (callback_ret < 0) {
      mg_cry_internal(fc(phys_ctx),
                      "external_ssl_ctx callback returned error: %i",
                      callback_ret);
      return 0;
   } else if (callback_ret > 0) {
      dom_ctx->ssl_ctx = (SSL_CTX *)ssl_ctx;
      if (!initialize_ssl(ebuf, sizeof(ebuf))) {
         mg_cry_internal(fc(phys_ctx), "%s", ebuf);
         return 0;
      }
      return 1;
   }
   /* else: external_ssl_ctx does not exist or returns 0,
    * CivetWeb should continue initializing SSL */

   /* If PEM file is not specified and the init_ssl callback
    * is not specified, setup will fail. */
   if (((pem = dom_ctx->config[SSL_CERTIFICATE]) == NULL)
       && (phys_ctx->callbacks.init_ssl == NULL)) {
      /* No certificate and no callback:
       * Essential data to set up TLS is missing.
       */
      mg_cry_internal(fc(phys_ctx),
                      "Initializing SSL failed: -%s is not set",
                      config_options[SSL_CERTIFICATE].name);
      return 0;
   }

   chain = dom_ctx->config[SSL_CERTIFICATE_CHAIN];
   if (chain == NULL) {
      chain = pem;
   }
   if ((chain != NULL) && (*chain == 0)) {
      chain = NULL;
   }

   if (!initialize_ssl(ebuf, sizeof(ebuf))) {
      mg_cry_internal(fc(phys_ctx), "%s", ebuf);
      return 0;
   }

   return init_ssl_ctx_impl(phys_ctx, dom_ctx, pem, chain);
}


static void
uninitialize_ssl(void)
{
#if defined(OPENSSL_API_1_1)

   if (mg_atomic_dec(&cryptolib_users) == 0) {

      /* Shutdown according to
       * https://wiki.openssl.org/index.php/Library_Initialization#Cleanup
       * http://stackoverflow.com/questions/29845527/how-to-properly-uninitialize-openssl
       */
      CONF_modules_unload(1);
#else
   int i;

   if (mg_atomic_dec(&cryptolib_users) == 0) {

      /* Shutdown according to
       * https://wiki.openssl.org/index.php/Library_Initialization#Cleanup
       * http://stackoverflow.com/questions/29845527/how-to-properly-uninitialize-openssl
       */
      CRYPTO_set_locking_callback(NULL);
      CRYPTO_set_id_callback(NULL);
      ENGINE_cleanup();
      CONF_modules_unload(1);
      ERR_free_strings();
      EVP_cleanup();
      CRYPTO_cleanup_all_ex_data();
      OPENSSL_REMOVE_THREAD_STATE();

      for (i = 0; i < CRYPTO_num_locks(); i++) {
         pthread_mutex_destroy(&ssl_mutexes[i]);
      }
      mg_free(ssl_mutexes);
      ssl_mutexes = NULL;
#endif /* OPENSSL_API_1_1 */
   }
}
#endif /* !NO_SSL */


static int
set_gpass_option(struct mg_context *phys_ctx, struct mg_domain_context *dom_ctx)
{
   if (phys_ctx) {
      struct mg_file file = STRUCT_FILE_INITIALIZER;
      const char *path;
      if (!dom_ctx) {
         dom_ctx = &(phys_ctx->dd);
      }
      path = dom_ctx->config[GLOBAL_PASSWORDS_FILE];
      if ((path != NULL) && !mg_stat(fc(phys_ctx), path, &file.stat)) {
         mg_cry_internal(fc(phys_ctx),
                         "Cannot open %s: %s",
                         path,
                         strerror(ERRNO));
         return 0;
      }
      return 1;
   }
   return 0;
}


static int
set_acl_option(struct mg_context *phys_ctx)
{
   return check_acl(phys_ctx, (uint32_t)0x7f000001UL) != -1;
}


static void
reset_per_request_attributes(struct mg_connection *conn)
{
   if (!conn) {
      return;
   }
   conn->connection_type =
       CONNECTION_TYPE_INVALID; /* Not yet a valid request/response */

   conn->num_bytes_sent = conn->consumed_content = 0;

   conn->path_info = NULL;
   conn->status_code = -1;
   conn->content_len = -1;
   conn->is_chunked = 0;
   conn->must_close = 0;
   conn->request_len = 0;
   conn->throttle = 0;
   conn->data_len = 0;
   conn->chunk_remainder = 0;
   conn->accept_gzip = 0;

   conn->response_info.content_length = conn->request_info.content_length = -1;
   conn->response_info.http_version = conn->request_info.http_version = NULL;
   conn->response_info.num_headers = conn->request_info.num_headers = 0;
   conn->response_info.status_text = NULL;
   conn->response_info.status_code = 0;

   conn->request_info.remote_user = NULL;
   conn->request_info.request_method = NULL;
   conn->request_info.request_uri = NULL;
   conn->request_info.local_uri = NULL;

#if defined(MG_LEGACY_INTERFACE)
   /* Legacy before split into local_uri and request_uri */
   conn->request_info.uri = NULL;
#endif
}


#if 0
/* Note: set_sock_timeout is not required for non-blocking sockets.
 * Leave this function here (commented out) for reference until
 * CivetWeb 1.9 is tested, and the tests confirme this function is
 * no longer required.
*/
static int
set_sock_timeout(SOCKET sock, int milliseconds)
{
        int r0 = 0, r1, r2;

#if defined(_WIN32)
        /* Windows specific */

        DWORD tv = (DWORD)milliseconds;

#else
        /* Linux, ... (not Windows) */

        struct timeval tv;

/* TCP_USER_TIMEOUT/RFC5482 (http://tools.ietf.org/html/rfc5482):
 * max. time waiting for the acknowledged of TCP data before the connection
 * will be forcefully closed and ETIMEDOUT is returned to the application.
 * If this option is not set, the default timeout of 20-30 minutes is used.
*/
/* #define TCP_USER_TIMEOUT (18) */

#if defined(TCP_USER_TIMEOUT)
        unsigned int uto = (unsigned int)milliseconds;
        r0 = setsockopt(sock, 6, TCP_USER_TIMEOUT, (const void *)&uto, sizeof(uto));
#endif

        memset(&tv, 0, sizeof(tv));
        tv.tv_sec = milliseconds / 1000;
        tv.tv_usec = (milliseconds * 1000) % 1000000;

#endif /* _WIN32 */

        r1 = setsockopt(
            sock, SOL_SOCKET, SO_RCVTIMEO, (SOCK_OPT_TYPE)&tv, sizeof(tv));
        r2 = setsockopt(
            sock, SOL_SOCKET, SO_SNDTIMEO, (SOCK_OPT_TYPE)&tv, sizeof(tv));

        return r0 || r1 || r2;
}
#endif


static int
set_tcp_nodelay(SOCKET sock, int nodelay_on)
{
   if (setsockopt(sock,
                  IPPROTO_TCP,
                  TCP_NODELAY,
                  (SOCK_OPT_TYPE)&nodelay_on,
                  sizeof(nodelay_on))
       != 0) {
      /* Error */
      return 1;
   }
   /* OK */
   return 0;
}


static void
close_socket_gracefully(struct mg_connection *conn)
{
#if defined(_WIN32)
   char buf[MG_BUF_LEN];
   int n;
#endif
   struct linger linger;
   int error_code = 0;
   int linger_timeout = -2;
   socklen_t opt_len = sizeof(error_code);

   if (!conn) {
      return;
   }

   /* http://msdn.microsoft.com/en-us/library/ms739165(v=vs.85).aspx:
    * "Note that enabling a nonzero timeout on a nonblocking socket
    * is not recommended.", so set it to blocking now */
   set_blocking_mode(conn->client.sock);

   /* Send FIN to the client */
   shutdown(conn->client.sock, SHUTDOWN_WR);


#if defined(_WIN32)
   /* Read and discard pending incoming data. If we do not do that and
    * close
    * the socket, the data in the send buffer may be discarded. This
    * behaviour is seen on Windows, when client keeps sending data
    * when server decides to close the connection; then when client
    * does recv() it gets no data back. */
   do {
      n = pull_inner(NULL, conn, buf, sizeof(buf), /* Timeout in s: */ 1.0);
   } while (n > 0);
#endif

   if (conn->dom_ctx->config[LINGER_TIMEOUT]) {
      linger_timeout = atoi(conn->dom_ctx->config[LINGER_TIMEOUT]);
   }

   /* Set linger option according to configuration */
   if (linger_timeout >= 0) {
      /* Set linger option to avoid socket hanging out after close. This
       * prevent ephemeral port exhaust problem under high QPS. */
      linger.l_onoff = 1;

#if defined(_MSC_VER)
#pragma warning(push)
#pragma warning(disable : 4244)
#endif
#if defined(GCC_DIAGNOSTIC)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wconversion"
#endif
      /* Data type of linger structure elements may differ,
       * so we don't know what cast we need here.
       * Disable type conversion warnings. */

      linger.l_linger = (linger_timeout + 999) / 1000;

#if defined(GCC_DIAGNOSTIC)
#pragma GCC diagnostic pop
#endif
#if defined(_MSC_VER)
#pragma warning(pop)
#endif

   } else {
      linger.l_onoff = 0;
      linger.l_linger = 0;
   }

   if (linger_timeout < -1) {
      /* Default: don't configure any linger */
   } else if (getsockopt(conn->client.sock,
                         SOL_SOCKET,
                         SO_ERROR,
#if defined(_WIN32) /* WinSock uses different data type here */
                         (char *)&error_code,
#else
                         &error_code,
#endif
                         &opt_len)
              != 0) {
      /* Cannot determine if socket is already closed. This should
       * not occur and never did in a test. Log an error message
       * and continue. */
      mg_cry_internal(conn,
                      "%s: getsockopt(SOL_SOCKET SO_ERROR) failed: %s",
                      __func__,
                      strerror(ERRNO));
   } else if (error_code == ECONNRESET) {
      /* Socket already closed by client/peer, close socket without linger
       */
   } else {

      /* Set linger timeout */
      if (setsockopt(conn->client.sock,
                     SOL_SOCKET,
                     SO_LINGER,
                     (char *)&linger,
                     sizeof(linger))
          != 0) {
         mg_cry_internal(
             conn,
             "%s: setsockopt(SOL_SOCKET SO_LINGER(%i,%i)) failed: %s",
             __func__,
             linger.l_onoff,
             linger.l_linger,
             strerror(ERRNO));
      }
   }

   /* Now we know that our FIN is ACK-ed, safe to close */
   closesocket(conn->client.sock);
   conn->client.sock = INVALID_SOCKET;
}


static void
close_connection(struct mg_connection *conn)
{
#if defined(USE_SERVER_STATS)
   conn->conn_state = 6; /* to close */
#endif

#if defined(USE_LUA) && defined(USE_WEBSOCKET)
   if (conn->lua_websocket_state) {
      lua_websocket_close(conn, conn->lua_websocket_state);
      conn->lua_websocket_state = NULL;
   }
#endif

   mg_lock_connection(conn);

   /* Set close flag, so keep-alive loops will stop */
   conn->must_close = 1;

   /* call the connection_close callback if assigned */
   if (conn->phys_ctx->callbacks.connection_close != NULL) {
      if (conn->phys_ctx->context_type == CONTEXT_SERVER) {
         conn->phys_ctx->callbacks.connection_close(conn);
      }
   }

   /* Reset user data, after close callback is called.
    * Do not reuse it. If the user needs a destructor,
    * it must be done in the connection_close callback. */
   mg_set_user_connection_data(conn, NULL);


#if defined(USE_SERVER_STATS)
   conn->conn_state = 7; /* closing */
#endif

#if !defined(NO_SSL)
   if (conn->ssl != NULL) {
      /* Run SSL_shutdown twice to ensure completely close SSL connection
       */
      SSL_shutdown(conn->ssl);
      SSL_free(conn->ssl);
      OPENSSL_REMOVE_THREAD_STATE();
      conn->ssl = NULL;
   }
#endif
   if (conn->client.sock != INVALID_SOCKET) {
      close_socket_gracefully(conn);
      conn->client.sock = INVALID_SOCKET;
   }

   if (conn->host) {
      mg_free((void *)conn->host);
      conn->host = NULL;
   }

   mg_unlock_connection(conn);

#if defined(USE_SERVER_STATS)
   conn->conn_state = 8; /* closed */
#endif
}


void
mg_close_connection(struct mg_connection *conn)
{
#if defined(USE_WEBSOCKET)
   struct mg_context *client_ctx = NULL;
#endif /* defined(USE_WEBSOCKET) */

   if ((conn == NULL) || (conn->phys_ctx == NULL)) {
      return;
   }

#if defined(USE_WEBSOCKET)
   if (conn->phys_ctx->context_type == CONTEXT_SERVER) {
      if (conn->in_websocket_handling) {
         /* Set close flag, so the server thread can exit. */
         conn->must_close = 1;
         return;
      }
   }
   if (conn->phys_ctx->context_type == CONTEXT_WS_CLIENT) {

      unsigned int i;

      /* ws/wss client */
      client_ctx = conn->phys_ctx;

      /* client context: loops must end */
      client_ctx->stop_flag = 1;
      conn->must_close = 1;

      /* We need to get the client thread out of the select/recv call
       * here. */
      /* Since we use a sleep quantum of some seconds to check for recv
       * timeouts, we will just wait a few seconds in mg_join_thread. */

      /* join worker thread */
      for (i = 0; i < client_ctx->cfg_worker_threads; i++) {
         if (client_ctx->worker_threadids[i] != 0) {
            mg_join_thread(client_ctx->worker_threadids[i]);
         }
      }
   }
#endif /* defined(USE_WEBSOCKET) */

   close_connection(conn);

#if !defined(NO_SSL)
   if (conn->client_ssl_ctx != NULL) {
      SSL_CTX_free((SSL_CTX *)conn->client_ssl_ctx);
   }
#endif

#if defined(USE_WEBSOCKET)
   if (client_ctx != NULL) {
      /* free context */
      mg_free(client_ctx->worker_threadids);
      mg_free(client_ctx);
      (void)pthread_mutex_destroy(&conn->mutex);
      mg_free(conn);
   } else if (conn->phys_ctx->context_type == CONTEXT_HTTP_CLIENT) {
      mg_free(conn);
   }
#else
   if (conn->phys_ctx->context_type == CONTEXT_HTTP_CLIENT) { /* Client */
      mg_free(conn);
   }
#endif /* defined(USE_WEBSOCKET) */
}


/* Only for memory statistics */
static struct mg_context common_client_context;


static struct mg_connection *
mg_connect_client_impl(const struct mg_client_options *client_options,
                       int use_ssl,
                       char *ebuf,
                       size_t ebuf_len)
{
   struct mg_connection *conn = NULL;
   SOCKET sock;
   union usa sa;
   struct sockaddr *psa;
   socklen_t len;

   unsigned max_req_size =
       (unsigned)atoi(config_options[MAX_REQUEST_SIZE].default_value);

   /* Size of structures, aligned to 8 bytes */
   size_t conn_size = ((sizeof(struct mg_connection) + 7) >> 3) << 3;
   size_t ctx_size = ((sizeof(struct mg_context) + 7) >> 3) << 3;

   conn = (struct mg_connection *)mg_calloc_ctx(
       1, conn_size + ctx_size + max_req_size, &common_client_context);

   if (conn == NULL) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "calloc(): %s",
                  strerror(ERRNO));
      return NULL;
   }

#if defined(GCC_DIAGNOSTIC)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wcast-align"
#endif /* defined(GCC_DIAGNOSTIC) */
   /* conn_size is aligned to 8 bytes */

   conn->phys_ctx = (struct mg_context *)(((char *)conn) + conn_size);

#if defined(GCC_DIAGNOSTIC)
#pragma GCC diagnostic pop
#endif /* defined(GCC_DIAGNOSTIC) */

   conn->buf = (((char *)conn) + conn_size + ctx_size);
   conn->buf_size = (int)max_req_size;
   conn->phys_ctx->context_type = CONTEXT_HTTP_CLIENT;
   conn->dom_ctx = &(conn->phys_ctx->dd);

   if (!connect_socket(&common_client_context,
                       client_options->host,
                       client_options->port,
                       use_ssl,
                       ebuf,
                       ebuf_len,
                       &sock,
                       &sa)) {
      /* ebuf is set by connect_socket,
       * free all memory and return NULL; */
      mg_free(conn);
      return NULL;
   }

#if !defined(NO_SSL)
#if defined(OPENSSL_API_1_1)
   if (use_ssl
       && (conn->client_ssl_ctx = SSL_CTX_new(TLS_client_method())) == NULL) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "SSL_CTX_new error");
      closesocket(sock);
      mg_free(conn);
      return NULL;
   }
#else
   if (use_ssl
       && (conn->client_ssl_ctx = SSL_CTX_new(SSLv23_client_method()))
              == NULL) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "SSL_CTX_new error");
      closesocket(sock);
      mg_free(conn);
      return NULL;
   }
#endif /* OPENSSL_API_1_1 */
#endif /* NO_SSL */


#if defined(USE_IPV6)
   len = (sa.sa.sa_family == AF_INET) ? sizeof(conn->client.rsa.sin)
                                      : sizeof(conn->client.rsa.sin6);
   psa = (sa.sa.sa_family == AF_INET)
             ? (struct sockaddr *)&(conn->client.rsa.sin)
             : (struct sockaddr *)&(conn->client.rsa.sin6);
#else
   len = sizeof(conn->client.rsa.sin);
   psa = (struct sockaddr *)&(conn->client.rsa.sin);
#endif

   conn->client.sock = sock;
   conn->client.lsa = sa;

   if (getsockname(sock, psa, &len) != 0) {
      mg_cry_internal(conn,
                      "%s: getsockname() failed: %s",
                      __func__,
                      strerror(ERRNO));
   }

   conn->client.is_ssl = use_ssl ? 1 : 0;
   if (0 != pthread_mutex_init(&conn->mutex, &pthread_mutex_attr)) {
      mg_snprintf(NULL,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "Can not create mutex");
#if !defined(NO_SSL)
      SSL_CTX_free(conn->client_ssl_ctx);
#endif
      closesocket(sock);
      mg_free(conn);
      return NULL;
   }


#if !defined(NO_SSL)
   if (use_ssl) {
      common_client_context.dd.ssl_ctx = conn->client_ssl_ctx;

      /* TODO: Check ssl_verify_peer and ssl_ca_path here.
       * SSL_CTX_set_verify call is needed to switch off server
       * certificate checking, which is off by default in OpenSSL and
       * on in yaSSL. */
      /* TODO: SSL_CTX_set_verify(conn->client_ssl_ctx,
       * SSL_VERIFY_PEER, verify_ssl_server); */

      if (client_options->client_cert) {
         if (!ssl_use_pem_file(&common_client_context,
                               &(common_client_context.dd),
                               client_options->client_cert,
                               NULL)) {
            mg_snprintf(NULL,
                        NULL, /* No truncation check for ebuf */
                        ebuf,
                        ebuf_len,
                        "Can not use SSL client certificate");
            SSL_CTX_free(conn->client_ssl_ctx);
            closesocket(sock);
            mg_free(conn);
            return NULL;
         }
      }

      if (client_options->server_cert) {
         SSL_CTX_load_verify_locations(conn->client_ssl_ctx,
                                       client_options->server_cert,
                                       NULL);
         SSL_CTX_set_verify(conn->client_ssl_ctx, SSL_VERIFY_PEER, NULL);
      } else {
         SSL_CTX_set_verify(conn->client_ssl_ctx, SSL_VERIFY_NONE, NULL);
      }

      if (!sslize(conn,
                  conn->client_ssl_ctx,
                  SSL_connect,
                  &(conn->phys_ctx->stop_flag),
                  client_options)) {
         mg_snprintf(NULL,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "SSL connection error");
         SSL_CTX_free(conn->client_ssl_ctx);
         closesocket(sock);
         mg_free(conn);
         return NULL;
      }
   }
#endif

   if (0 != set_non_blocking_mode(sock)) {
      mg_cry_internal(conn,
                      "Cannot set non-blocking mode for client %s:%i",
                      client_options->host,
                      client_options->port);
   }

   return conn;
}


CIVETWEB_API struct mg_connection *
mg_connect_client_secure(const struct mg_client_options *client_options,
                         char *error_buffer,
                         size_t error_buffer_size)
{
   return mg_connect_client_impl(client_options,
                                 1,
                                 error_buffer,
                                 error_buffer_size);
}


struct mg_connection *
mg_connect_client(const char *host,
                  int port,
                  int use_ssl,
                  char *error_buffer,
                  size_t error_buffer_size)
{
   struct mg_client_options opts;
   memset(&opts, 0, sizeof(opts));
   opts.host = host;
   opts.port = port;
   return mg_connect_client_impl(&opts,
                                 use_ssl,
                                 error_buffer,
                                 error_buffer_size);
}


static const struct {
   const char *proto;
   size_t proto_len;
   unsigned default_port;
} abs_uri_protocols[] = {{"http://", 7, 80},
                         {"https://", 8, 443},
                         {"ws://", 5, 80},
                         {"wss://", 6, 443},
                         {NULL, 0, 0}};


/* Check if the uri is valid.
 * return 0 for invalid uri,
 * return 1 for *,
 * return 2 for relative uri,
 * return 3 for absolute uri without port,
 * return 4 for absolute uri with port */
static int
get_uri_type(const char *uri)
{
   int i;
   const char *hostend, *portbegin;
   char *portend;
   unsigned long port;

   /* According to the HTTP standard
    * http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.1.2
    * URI can be an asterisk (*) or should start with slash (relative uri),
    * or it should start with the protocol (absolute uri). */
   if ((uri[0] == '*') && (uri[1] == '\0')) {
      /* asterisk */
      return 1;
   }

   /* Valid URIs according to RFC 3986
    * (https://www.ietf.org/rfc/rfc3986.txt)
    * must only contain reserved characters :/?#[]@!$&'()*+,;=
    * and unreserved characters A-Z a-z 0-9 and -._~
    * and % encoded symbols.
    */
   for (i = 0; uri[i] != 0; i++) {
      if (uri[i] < 33) {
         /* control characters and spaces are invalid */
         return 0;
      }
      if (uri[i] > 126) {
         /* non-ascii characters must be % encoded */
         return 0;
      } else {
         switch (uri[i]) {
         case '"':  /* 34 */
         case '<':  /* 60 */
         case '>':  /* 62 */
         case '\\': /* 92 */
         case '^':  /* 94 */
         case '`':  /* 96 */
         case '{':  /* 123 */
         case '|':  /* 124 */
         case '}':  /* 125 */
            return 0;
         default:
            /* character is ok */
            break;
         }
      }
   }

   /* A relative uri starts with a / character */
   if (uri[0] == '/') {
      /* relative uri */
      return 2;
   }

   /* It could be an absolute uri: */
   /* This function only checks if the uri is valid, not if it is
    * addressing the current server. So civetweb can also be used
    * as a proxy server. */
   for (i = 0; abs_uri_protocols[i].proto != NULL; i++) {
      if (mg_strncasecmp(uri,
                         abs_uri_protocols[i].proto,
                         abs_uri_protocols[i].proto_len)
          == 0) {

         hostend = strchr(uri + abs_uri_protocols[i].proto_len, '/');
         if (!hostend) {
            return 0;
         }
         portbegin = strchr(uri + abs_uri_protocols[i].proto_len, ':');
         if (!portbegin) {
            return 3;
         }

         port = strtoul(portbegin + 1, &portend, 10);
         if ((portend != hostend) || (port <= 0) || !is_valid_port(port)) {
            return 0;
         }

         return 4;
      }
   }

   return 0;
}


/* Return NULL or the relative uri at the current server */
static const char *
get_rel_url_at_current_server(const char *uri, const struct mg_connection *conn)
{
   const char *server_domain;
   size_t server_domain_len;
   size_t request_domain_len = 0;
   unsigned long port = 0;
   int i, auth_domain_check_enabled;
   const char *hostbegin = NULL;
   const char *hostend = NULL;
   const char *portbegin;
   char *portend;

   auth_domain_check_enabled =
       !mg_strcasecmp(conn->dom_ctx->config[ENABLE_AUTH_DOMAIN_CHECK], "yes");

   /* DNS is case insensitive, so use case insensitive string compare here
    */
   for (i = 0; abs_uri_protocols[i].proto != NULL; i++) {
      if (mg_strncasecmp(uri,
                         abs_uri_protocols[i].proto,
                         abs_uri_protocols[i].proto_len)
          == 0) {

         hostbegin = uri + abs_uri_protocols[i].proto_len;
         hostend = strchr(hostbegin, '/');
         if (!hostend) {
            return 0;
         }
         portbegin = strchr(hostbegin, ':');
         if ((!portbegin) || (portbegin > hostend)) {
            port = abs_uri_protocols[i].default_port;
            request_domain_len = (size_t)(hostend - hostbegin);
         } else {
            port = strtoul(portbegin + 1, &portend, 10);
            if ((portend != hostend) || (port <= 0)
                || !is_valid_port(port)) {
               return 0;
            }
            request_domain_len = (size_t)(portbegin - hostbegin);
         }
         /* protocol found, port set */
         break;
      }
   }

   if (!port) {
      /* port remains 0 if the protocol is not found */
      return 0;
   }

/* Check if the request is directed to a different server. */
/* First check if the port is the same (IPv4 and IPv6). */
#if defined(USE_IPV6)
   if (conn->client.lsa.sa.sa_family == AF_INET6) {
      if (ntohs(conn->client.lsa.sin6.sin6_port) != port) {
         /* Request is directed to a different port */
         return 0;
      }
   } else
#endif
   {
      if (ntohs(conn->client.lsa.sin.sin_port) != port) {
         /* Request is directed to a different port */
         return 0;
      }
   }

   /* Finally check if the server corresponds to the authentication
    * domain of the server (the server domain).
    * Allow full matches (like http://mydomain.com/path/file.ext), and
    * allow subdomain matches (like http://www.mydomain.com/path/file.ext),
    * but do not allow substrings (like
    * http://notmydomain.com/path/file.ext
    * or http://mydomain.com.fake/path/file.ext).
    */
   if (auth_domain_check_enabled) {
      server_domain = conn->dom_ctx->config[AUTHENTICATION_DOMAIN];
      server_domain_len = strlen(server_domain);
      if ((server_domain_len == 0) || (hostbegin == NULL)) {
         return 0;
      }
      if ((request_domain_len == server_domain_len)
          && (!memcmp(server_domain, hostbegin, server_domain_len))) {
         /* Request is directed to this server - full name match. */
      } else {
         if (request_domain_len < (server_domain_len + 2)) {
            /* Request is directed to another server: The server name
             * is longer than the request name.
             * Drop this case here to avoid overflows in the
             * following checks. */
            return 0;
         }
         if (hostbegin[request_domain_len - server_domain_len - 1] != '.') {
            /* Request is directed to another server: It could be a
             * substring
             * like notmyserver.com */
            return 0;
         }
         if (0
             != memcmp(server_domain,
                       hostbegin + request_domain_len - server_domain_len,
                       server_domain_len)) {
            /* Request is directed to another server:
             * The server name is different. */
            return 0;
         }
      }
   }

   return hostend;
}


static int
get_message(struct mg_connection *conn, char *ebuf, size_t ebuf_len, int *err)
{
   if (ebuf_len > 0) {
      ebuf[0] = '\0';
   }
   *err = 0;

   reset_per_request_attributes(conn);

   if (!conn) {
      mg_snprintf(conn,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "Internal error");
      *err = 500;
      return 0;
   }
   /* Set the time the request was received. This value should be used for
    * timeouts. */
   clock_gettime(CLOCK_MONOTONIC, &(conn->req_time));

   conn->request_len =
       read_message(NULL, conn, conn->buf, conn->buf_size, &conn->data_len);
   DEBUG_ASSERT(conn->request_len < 0 || conn->data_len >= conn->request_len);
   if ((conn->request_len >= 0) && (conn->data_len < conn->request_len)) {
      mg_snprintf(conn,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "Invalid message size");
      *err = 500;
      return 0;
   }

   if ((conn->request_len == 0) && (conn->data_len == conn->buf_size)) {
      mg_snprintf(conn,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "Message too large");
      *err = 413;
      return 0;
   }

   if (conn->request_len <= 0) {
      if (conn->data_len > 0) {
         mg_snprintf(conn,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "%s",
                     "Malformed message");
         *err = 400;
      } else {
         /* Server did not recv anything -> just close the connection */
         conn->must_close = 1;
         mg_snprintf(conn,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "%s",
                     "No data received");
         *err = 0;
      }
      return 0;
   }
   return 1;
}


static int
get_request(struct mg_connection *conn, char *ebuf, size_t ebuf_len, int *err)
{
   const char *cl;
   if (!get_message(conn, ebuf, ebuf_len, err)) {
      return 0;
   }

   if (parse_http_request(conn->buf, conn->buf_size, &conn->request_info)
       <= 0) {
      mg_snprintf(conn,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "Bad request");
      *err = 400;
      return 0;
   }

   /* Message is a valid request */

   /* Is there a "host" ? */
   conn->host = alloc_get_host(conn);
   if (!conn->host) {
      mg_snprintf(conn,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "Bad request: Host mismatch");
      *err = 400;
      return 0;
   }

   /* Do we know the content length? */
   if ((cl = get_header(conn->request_info.http_headers,
                        conn->request_info.num_headers,
                        "Content-Length"))
       != NULL) {
      /* Request/response has content length set */
      char *endptr = NULL;
      conn->content_len = strtoll(cl, &endptr, 10);
      if (endptr == cl) {
         mg_snprintf(conn,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "%s",
                     "Bad request");
         *err = 411;
         return 0;
      }
      /* Publish the content length back to the request info. */
      conn->request_info.content_length = conn->content_len;
   } else if ((cl = get_header(conn->request_info.http_headers,
                               conn->request_info.num_headers,
                               "Transfer-Encoding"))
                  != NULL
              && !mg_strcasecmp(cl, "chunked")) {
      conn->is_chunked = 1;
      conn->content_len = -1; /* unknown content length */
   } else {
      const struct mg_http_method_info *meth =
          get_http_method_info(conn->request_info.request_method);
      if (!meth) {
         /* No valid HTTP method */
         mg_snprintf(conn,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "%s",
                     "Bad request");
         *err = 411;
         return 0;
      }
      if (meth->request_has_body) {
         /* POST or PUT request without content length set */
         conn->content_len = -1; /* unknown content length */
      } else {
         /* Other request */
         conn->content_len = 0; /* No content */
      }
   }

   conn->connection_type = CONNECTION_TYPE_REQUEST; /* Valid request */
   return 1;
}


/* conn is assumed to be valid in this internal function */
static int
get_response(struct mg_connection *conn, char *ebuf, size_t ebuf_len, int *err)
{
   const char *cl;
   if (!get_message(conn, ebuf, ebuf_len, err)) {
      return 0;
   }

   if (parse_http_response(conn->buf, conn->buf_size, &conn->response_info)
       <= 0) {
      mg_snprintf(conn,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "Bad response");
      *err = 400;
      return 0;
   }

   /* Message is a valid response */

   /* Do we know the content length? */
   if ((cl = get_header(conn->response_info.http_headers,
                        conn->response_info.num_headers,
                        "Content-Length"))
       != NULL) {
      /* Request/response has content length set */
      char *endptr = NULL;
      conn->content_len = strtoll(cl, &endptr, 10);
      if (endptr == cl) {
         mg_snprintf(conn,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "%s",
                     "Bad request");
         *err = 411;
         return 0;
      }
      /* Publish the content length back to the response info. */
      conn->response_info.content_length = conn->content_len;

      /* TODO: check if it is still used in response_info */
      conn->request_info.content_length = conn->content_len;

   } else if ((cl = get_header(conn->response_info.http_headers,
                               conn->response_info.num_headers,
                               "Transfer-Encoding"))
                  != NULL
              && !mg_strcasecmp(cl, "chunked")) {
      conn->is_chunked = 1;
      conn->content_len = -1; /* unknown content length */
   } else {
      conn->content_len = -1; /* unknown content length */
   }

   conn->connection_type = CONNECTION_TYPE_RESPONSE; /* Valid response */
   return 1;
}


int
mg_get_response(struct mg_connection *conn,
                char *ebuf,
                size_t ebuf_len,
                int timeout)
{
   int err, ret;
   char txt[32]; /* will not overflow */
   char *save_timeout;
   char *new_timeout;

   if (ebuf_len > 0) {
      ebuf[0] = '\0';
   }

   if (!conn) {
      mg_snprintf(conn,
                  NULL, /* No truncation check for ebuf */
                  ebuf,
                  ebuf_len,
                  "%s",
                  "Parameter error");
      return -1;
   }

   /* Implementation of API function for HTTP clients */
   save_timeout = conn->dom_ctx->config[REQUEST_TIMEOUT];

   if (timeout >= 0) {
      mg_snprintf(conn, NULL, txt, sizeof(txt), "%i", timeout);
      new_timeout = txt;
      /* Not required for non-blocking sockets.
      set_sock_timeout(conn->client.sock, timeout);
      */
   } else {
      new_timeout = NULL;
   }

   conn->dom_ctx->config[REQUEST_TIMEOUT] = new_timeout;
   ret = get_response(conn, ebuf, ebuf_len, &err);
   conn->dom_ctx->config[REQUEST_TIMEOUT] = save_timeout;

#if defined(MG_LEGACY_INTERFACE)
   /* TODO: 1) uri is deprecated;
    *       2) here, ri.uri is the http response code */
   conn->request_info.uri = conn->request_info.request_uri;
#endif
   conn->request_info.local_uri = conn->request_info.request_uri;

   /* TODO (mid): Define proper return values - maybe return length?
    * For the first test use <0 for error and >0 for OK */
   return (ret == 0) ? -1 : +1;
}


struct mg_connection *
mg_download(const char *host,
            int port,
            int use_ssl,
            char *ebuf,
            size_t ebuf_len,
            const char *fmt,
            ...)
{
   struct mg_connection *conn;
   va_list ap;
   int i;
   int reqerr;

   if (ebuf_len > 0) {
      ebuf[0] = '\0';
   }

   va_start(ap, fmt);

   /* open a connection */
   conn = mg_connect_client(host, port, use_ssl, ebuf, ebuf_len);

   if (conn != NULL) {
      i = mg_vprintf(conn, fmt, ap);
      if (i <= 0) {
         mg_snprintf(conn,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     ebuf_len,
                     "%s",
                     "Error sending request");
      } else {
         get_response(conn, ebuf, ebuf_len, &reqerr);

#if defined(MG_LEGACY_INTERFACE)
         /* TODO: 1) uri is deprecated;
          *       2) here, ri.uri is the http response code */
         conn->request_info.uri = conn->request_info.request_uri;
#endif
         conn->request_info.local_uri = conn->request_info.request_uri;
      }
   }

   /* if an error occurred, close the connection */
   if ((ebuf[0] != '\0') && (conn != NULL)) {
      mg_close_connection(conn);
      conn = NULL;
   }

   va_end(ap);
   return conn;
}


struct websocket_client_thread_data {
   struct mg_connection *conn;
   mg_websocket_data_handler data_handler;
   mg_websocket_close_handler close_handler;
   void *callback_data;
};


#if defined(USE_WEBSOCKET)
#if defined(_WIN32)
static unsigned __stdcall websocket_client_thread(void *data)
#else
static void *
websocket_client_thread(void *data)
#endif
{
   struct websocket_client_thread_data *cdata =
       (struct websocket_client_thread_data *)data;

#if !defined(_WIN32)
   struct sigaction sa;

   /* Ignore SIGPIPE */
   memset(&sa, 0, sizeof(sa));
   sa.sa_handler = SIG_IGN;
   sigaction(SIGPIPE, &sa, NULL);
#endif

   mg_set_thread_name("ws-clnt");

   if (cdata->conn->phys_ctx) {
      if (cdata->conn->phys_ctx->callbacks.init_thread) {
         /* 3 indicates a websocket client thread */
         /* TODO: check if conn->phys_ctx can be set */
         cdata->conn->phys_ctx->callbacks.init_thread(cdata->conn->phys_ctx,
                                                      3);
      }
   }

   read_websocket(cdata->conn, cdata->data_handler, cdata->callback_data);

   DEBUG_TRACE("%s", "Websocket client thread exited\n");

   if (cdata->close_handler != NULL) {
      cdata->close_handler(cdata->conn, cdata->callback_data);
   }

   /* The websocket_client context has only this thread. If it runs out,
      set the stop_flag to 2 (= "stopped"). */
   cdata->conn->phys_ctx->stop_flag = 2;

   mg_free((void *)cdata);

#if defined(_WIN32)
   return 0;
#else
   return NULL;
#endif
}
#endif


struct mg_connection *
mg_connect_websocket_client(const char *host,
                            int port,
                            int use_ssl,
                            char *error_buffer,
                            size_t error_buffer_size,
                            const char *path,
                            const char *origin,
                            mg_websocket_data_handler data_func,
                            mg_websocket_close_handler close_func,
                            void *user_data)
{
   struct mg_connection *conn = NULL;

#if defined(USE_WEBSOCKET)
   struct mg_context *newctx = NULL;
   struct websocket_client_thread_data *thread_data;
   static const char *magic = "x3JJHMbDL1EzLkh9GBhXDw==";
   static const char *handshake_req;

   if (origin != NULL) {
      handshake_req = "GET %s HTTP/1.1\r\n"
                      "Host: %s\r\n"
                      "Upgrade: websocket\r\n"
                      "Connection: Upgrade\r\n"
                      "Sec-WebSocket-Key: %s\r\n"
                      "Sec-WebSocket-Version: 13\r\n"
                      "Origin: %s\r\n"
                      "\r\n";
   } else {
      handshake_req = "GET %s HTTP/1.1\r\n"
                      "Host: %s\r\n"
                      "Upgrade: websocket\r\n"
                      "Connection: Upgrade\r\n"
                      "Sec-WebSocket-Key: %s\r\n"
                      "Sec-WebSocket-Version: 13\r\n"
                      "\r\n";
   }

#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wformat-nonliteral"
#endif

   /* Establish the client connection and request upgrade */
   conn = mg_download(host,
                      port,
                      use_ssl,
                      error_buffer,
                      error_buffer_size,
                      handshake_req,
                      path,
                      host,
                      magic,
                      origin);

#if defined(__clang__)
#pragma clang diagnostic pop
#endif

   /* Connection object will be null if something goes wrong */
   if (conn == NULL) {
      if (!*error_buffer) {
         /* There should be already an error message */
         mg_snprintf(conn,
                     NULL, /* No truncation check for ebuf */
                     error_buffer,
                     error_buffer_size,
                     "Unexpected error");
      }
      return NULL;
   }

   if (conn->response_info.status_code != 101) {
      /* We sent an "upgrade" request. For a correct websocket
       * protocol handshake, we expect a "101 Continue" response.
       * Otherwise it is a protocol violation. Maybe the HTTP
       * Server does not know websockets. */
      if (!*error_buffer) {
         /* set an error, if not yet set */
         mg_snprintf(conn,
                     NULL, /* No truncation check for ebuf */
                     error_buffer,
                     error_buffer_size,
                     "Unexpected server reply");
      }

      DEBUG_TRACE("Websocket client connect error: %s\r\n", error_buffer);
      mg_free(conn);
      return NULL;
   }

   /* For client connections, mg_context is fake. Since we need to set a
    * callback function, we need to create a copy and modify it. */
   newctx = (struct mg_context *)mg_malloc(sizeof(struct mg_context));
   if (!newctx) {
      DEBUG_TRACE("%s\r\n", "Out of memory");
      mg_free(conn);
      return NULL;
   }

   memcpy(newctx, conn->phys_ctx, sizeof(struct mg_context));
   newctx->user_data = user_data;
   newctx->context_type = CONTEXT_WS_CLIENT; /* ws/wss client context */
   newctx->cfg_worker_threads = 1; /* one worker thread will be created */
   newctx->worker_threadids =
       (pthread_t *)mg_calloc_ctx(newctx->cfg_worker_threads,
                                  sizeof(pthread_t),
                                  newctx);

   conn->phys_ctx = newctx;
   conn->dom_ctx = &(newctx->dd);

   thread_data = (struct websocket_client_thread_data *)
       mg_calloc_ctx(sizeof(struct websocket_client_thread_data), 1, newctx);
   if (!thread_data) {
      DEBUG_TRACE("%s\r\n", "Out of memory");
      mg_free(newctx);
      mg_free(conn);
      return NULL;
   }

   thread_data->conn = conn;
   thread_data->data_handler = data_func;
   thread_data->close_handler = close_func;
   thread_data->callback_data = user_data;

   /* Start a thread to read the websocket client connection
    * This thread will automatically stop when mg_disconnect is
    * called on the client connection */
   if (mg_start_thread_with_id(websocket_client_thread,
                               (void *)thread_data,
                               newctx->worker_threadids)
       != 0) {
      mg_free((void *)thread_data);
      mg_free((void *)newctx->worker_threadids);
      mg_free((void *)newctx);
      mg_free((void *)conn);
      conn = NULL;
      DEBUG_TRACE("%s",
                  "Websocket client connect thread could not be started\r\n");
   }

#else
   /* Appease "unused parameter" warnings */
   (void)host;
   (void)port;
   (void)use_ssl;
   (void)error_buffer;
   (void)error_buffer_size;
   (void)path;
   (void)origin;
   (void)user_data;
   (void)data_func;
   (void)close_func;
#endif

   return conn;
}


/* Prepare connection data structure */
static void
init_connection(struct mg_connection *conn)
{
   /* Is keep alive allowed by the server */
   int keep_alive_enabled =
       !mg_strcasecmp(conn->dom_ctx->config[ENABLE_KEEP_ALIVE], "yes");

   if (!keep_alive_enabled) {
      conn->must_close = 1;
   }

   /* Important: on new connection, reset the receiving buffer. Credit
    * goes to crule42. */
   conn->data_len = 0;
   conn->handled_requests = 0;
   mg_set_user_connection_data(conn, NULL);

#if defined(USE_SERVER_STATS)
   conn->conn_state = 2; /* init */
#endif

   /* call the init_connection callback if assigned */
   if (conn->phys_ctx->callbacks.init_connection != NULL) {
      if (conn->phys_ctx->context_type == CONTEXT_SERVER) {
         void *conn_data = NULL;
         conn->phys_ctx->callbacks.init_connection(conn, &conn_data);
         mg_set_user_connection_data(conn, conn_data);
      }
   }
}


/* Process a connection - may handle multiple requests
 * using the same connection.
 * Must be called with a valid connection (conn  and
 * conn->phys_ctx must be valid).
 */
static void
process_new_connection(struct mg_connection *conn)
{
   struct mg_request_info *ri = &conn->request_info;
   int keep_alive, discard_len;
   char ebuf[100];
   const char *hostend;
   int reqerr, uri_type;

#if defined(USE_SERVER_STATS)
   int mcon = mg_atomic_inc(&(conn->phys_ctx->active_connections));
   mg_atomic_add(&(conn->phys_ctx->total_connections), 1);
   if (mcon > (conn->phys_ctx->max_connections)) {
      /* could use atomic compare exchange, but this
       * seems overkill for statistics data */
      conn->phys_ctx->max_connections = mcon;
   }
#endif

   init_connection(conn);

   DEBUG_TRACE("Start processing connection from %s",
               conn->request_info.remote_addr);

   /* Loop over multiple requests sent using the same connection
    * (while "keep alive"). */
   do {

      DEBUG_TRACE("calling get_request (%i times for this connection)",
                  conn->handled_requests + 1);

#if defined(USE_SERVER_STATS)
      conn->conn_state = 3; /* ready */
#endif

      if (!get_request(conn, ebuf, sizeof(ebuf), &reqerr)) {
         /* The request sent by the client could not be understood by
          * the server, or it was incomplete or a timeout. Send an
          * error message and close the connection. */
         if (reqerr > 0) {
            DEBUG_ASSERT(ebuf[0] != '\0');
            mg_send_http_error(conn, reqerr, "%s", ebuf);
         }
      } else if (strcmp(ri->http_version, "1.0")
                 && strcmp(ri->http_version, "1.1")) {
         mg_snprintf(conn,
                     NULL, /* No truncation check for ebuf */
                     ebuf,
                     sizeof(ebuf),
                     "Bad HTTP version: [%s]",
                     ri->http_version);
         mg_send_http_error(conn, 505, "%s", ebuf);
      }

      if (ebuf[0] == '\0') {
         uri_type = get_uri_type(conn->request_info.request_uri);
         switch (uri_type) {
         case 1:
            /* Asterisk */
            conn->request_info.local_uri = NULL;
            break;
         case 2:
            /* relative uri */
            conn->request_info.local_uri = conn->request_info.request_uri;
            break;
         case 3:
         case 4:
            /* absolute uri (with/without port) */
            hostend = get_rel_url_at_current_server(
                conn->request_info.request_uri, conn);
            if (hostend) {
               conn->request_info.local_uri = hostend;
            } else {
               conn->request_info.local_uri = NULL;
            }
            break;
         default:
            mg_snprintf(conn,
                        NULL, /* No truncation check for ebuf */
                        ebuf,
                        sizeof(ebuf),
                        "Invalid URI");
            mg_send_http_error(conn, 400, "%s", ebuf);
            conn->request_info.local_uri = NULL;
            break;
         }

#if defined(MG_LEGACY_INTERFACE)
         /* Legacy before split into local_uri and request_uri */
         conn->request_info.uri = conn->request_info.local_uri;
#endif
      }

      DEBUG_TRACE("http: %s, error: %s",
                  (ri->http_version ? ri->http_version : "none"),
                  (ebuf[0] ? ebuf : "none"));

      if (ebuf[0] == '\0') {
         if (conn->request_info.local_uri) {

/* handle request to local server */
#if defined(USE_SERVER_STATS)
            conn->conn_state = 4; /* processing */
#endif
            handle_request(conn);

#if defined(USE_SERVER_STATS)
            conn->conn_state = 5; /* processed */

            mg_atomic_add(&(conn->phys_ctx->total_data_read),
                          conn->consumed_content);
            mg_atomic_add(&(conn->phys_ctx->total_data_written),
                          conn->num_bytes_sent);
#endif

            DEBUG_TRACE("%s", "handle_request done");

            if (conn->phys_ctx->callbacks.end_request != NULL) {
               conn->phys_ctx->callbacks.end_request(conn,
                                                     conn->status_code);
               DEBUG_TRACE("%s", "end_request callback done");
            }
            log_access(conn);
         } else {
            /* TODO: handle non-local request (PROXY) */
            conn->must_close = 1;
         }
      } else {
         conn->must_close = 1;
      }

      if (ri->remote_user != NULL) {
         mg_free((void *)ri->remote_user);
         /* Important! When having connections with and without auth
          * would cause double free and then crash */
         ri->remote_user = NULL;
      }

      /* NOTE(lsm): order is important here. should_keep_alive() call
       * is using parsed request, which will be invalid after
       * memmove's below.
       * Therefore, memorize should_keep_alive() result now for later
       * use in loop exit condition. */
      keep_alive = (conn->phys_ctx->stop_flag == 0) && should_keep_alive(conn)
                   && (conn->content_len >= 0);


      /* Discard all buffered data for this request */
      discard_len = ((conn->content_len >= 0) && (conn->request_len > 0)
                     && ((conn->request_len + conn->content_len)
                         < (int64_t)conn->data_len))
                        ? (int)(conn->request_len + conn->content_len)
                        : conn->data_len;
      DEBUG_ASSERT(discard_len >= 0);
      if (discard_len < 0) {
         DEBUG_TRACE("internal error: discard_len = %li",
                     (long int)discard_len);
         break;
      }
      conn->data_len -= discard_len;
      if (conn->data_len > 0) {
         DEBUG_TRACE("discard_len = %lu", (long unsigned)discard_len);
         memmove(conn->buf, conn->buf + discard_len, (size_t)conn->data_len);
      }

      DEBUG_ASSERT(conn->data_len >= 0);
      DEBUG_ASSERT(conn->data_len <= conn->buf_size);

      if ((conn->data_len < 0) || (conn->data_len > conn->buf_size)) {
         DEBUG_TRACE("internal error: data_len = %li, buf_size = %li",
                     (long int)conn->data_len,
                     (long int)conn->buf_size);
         break;
      }

      conn->handled_requests++;

   } while (keep_alive);

   DEBUG_TRACE("Done processing connection from %s (%f sec)",
               conn->request_info.remote_addr,
               difftime(time(NULL), conn->conn_birth_time));

   close_connection(conn);

#if defined(USE_SERVER_STATS)
   mg_atomic_add(&(conn->phys_ctx->total_requests), conn->handled_requests);
   mg_atomic_dec(&(conn->phys_ctx->active_connections));
#endif
}


#if defined(ALTERNATIVE_QUEUE)

static void
produce_socket(struct mg_context *ctx, const struct socket *sp)
{
   unsigned int i;

   while (!ctx->stop_flag) {
      for (i = 0; i < ctx->cfg_worker_threads; i++) {
         /* find a free worker slot and signal it */
         if (ctx->client_socks[i].in_use == 0) {
            ctx->client_socks[i] = *sp;
            ctx->client_socks[i].in_use = 1;
            event_signal(ctx->client_wait_events[i]);
            return;
         }
      }
      /* queue is full */
      mg_sleep(1);
   }
}


static int
consume_socket(struct mg_context *ctx, struct socket *sp, int thread_index)
{
   DEBUG_TRACE("%s", "going idle");
   ctx->client_socks[thread_index].in_use = 0;
   event_wait(ctx->client_wait_events[thread_index]);
   *sp = ctx->client_socks[thread_index];
   DEBUG_TRACE("grabbed socket %d, going busy", sp ? sp->sock : -1);

   return !ctx->stop_flag;
}

#else /* ALTERNATIVE_QUEUE */

/* Worker threads take accepted socket from the queue */
static int
consume_socket(struct mg_context *ctx, struct socket *sp, int thread_index)
{
#define QUEUE_SIZE(ctx) ((int)(ARRAY_SIZE(ctx->queue)))

   (void)thread_index;

   (void)pthread_mutex_lock(&ctx->thread_mutex);
   DEBUG_TRACE("%s", "going idle");

   /* If the queue is empty, wait. We're idle at this point. */
   while ((ctx->sq_head == ctx->sq_tail) && (ctx->stop_flag == 0)) {
      pthread_cond_wait(&ctx->sq_full, &ctx->thread_mutex);
   }

   /* If we're stopping, sq_head may be equal to sq_tail. */
   if (ctx->sq_head > ctx->sq_tail) {
      /* Copy socket from the queue and increment tail */
      *sp = ctx->queue[ctx->sq_tail % QUEUE_SIZE(ctx)];
      ctx->sq_tail++;

      DEBUG_TRACE("grabbed socket %d, going busy", sp ? sp->sock : -1);

      /* Wrap pointers if needed */
      while (ctx->sq_tail > QUEUE_SIZE(ctx)) {
         ctx->sq_tail -= QUEUE_SIZE(ctx);
         ctx->sq_head -= QUEUE_SIZE(ctx);
      }
   }

   (void)pthread_cond_signal(&ctx->sq_empty);
   (void)pthread_mutex_unlock(&ctx->thread_mutex);

   return !ctx->stop_flag;
#undef QUEUE_SIZE
}


/* Master thread adds accepted socket to a queue */
static void
produce_socket(struct mg_context *ctx, const struct socket *sp)
{
#define QUEUE_SIZE(ctx) ((int)(ARRAY_SIZE(ctx->queue)))
   if (!ctx) {
      return;
   }
   (void)pthread_mutex_lock(&ctx->thread_mutex);

   /* If the queue is full, wait */
   while ((ctx->stop_flag == 0)
          && (ctx->sq_head - ctx->sq_tail >= QUEUE_SIZE(ctx))) {
      (void)pthread_cond_wait(&ctx->sq_empty, &ctx->thread_mutex);
   }

   if (ctx->sq_head - ctx->sq_tail < QUEUE_SIZE(ctx)) {
      /* Copy socket to the queue and increment head */
      ctx->queue[ctx->sq_head % QUEUE_SIZE(ctx)] = *sp;
      ctx->sq_head++;
      DEBUG_TRACE("queued socket %d", sp ? sp->sock : -1);
   }

   (void)pthread_cond_signal(&ctx->sq_full);
   (void)pthread_mutex_unlock(&ctx->thread_mutex);
#undef QUEUE_SIZE
}
#endif /* ALTERNATIVE_QUEUE */


struct worker_thread_args {
   struct mg_context *ctx;
   int index;
};


static void *
worker_thread_run(struct worker_thread_args *thread_args)
{
   struct mg_context *ctx = thread_args->ctx;
   struct mg_connection *conn;
   struct mg_workerTLS tls;
#if defined(MG_LEGACY_INTERFACE)
   uint32_t addr;
#endif

   mg_set_thread_name("worker");

   tls.is_master = 0;
   tls.thread_idx = (unsigned)mg_atomic_inc(&thread_idx_max);
#if defined(_WIN32)
   tls.pthread_cond_helper_mutex = CreateEvent(NULL, FALSE, FALSE, NULL);
#endif

   /* Initialize thread local storage before calling any callback */
   pthread_setspecific(sTlsKey, &tls);

   if (ctx->callbacks.init_thread) {
      /* call init_thread for a worker thread (type 1) */
      ctx->callbacks.init_thread(ctx, 1);
   }

   /* Connection structure has been pre-allocated */
   if (((int)thread_args->index < 0)
       || ((unsigned)thread_args->index
           >= (unsigned)ctx->cfg_worker_threads)) {
      mg_cry_internal(fc(ctx),
                      "Internal error: Invalid worker index %i",
                      (int)thread_args->index);
      return NULL;
   }
   conn = ctx->worker_connections + thread_args->index;

   /* Request buffers are not pre-allocated. They are private to the
    * request and do not contain any state information that might be
    * of interest to anyone observing a server status.  */
   conn->buf = (char *)mg_malloc_ctx(ctx->max_request_size, conn->phys_ctx);
   if (conn->buf == NULL) {
      mg_cry_internal(fc(ctx),
                      "Out of memory: Cannot allocate buffer for worker %i",
                      (int)thread_args->index);
      return NULL;
   }
   conn->buf_size = (int)ctx->max_request_size;

   conn->phys_ctx = ctx;
   conn->dom_ctx = &(ctx->dd); /* Use default domain and default host */
   conn->host = NULL;          /* until we have more information. */

   conn->thread_index = thread_args->index;
   conn->request_info.user_data = ctx->user_data;
   /* Allocate a mutex for this connection to allow communication both
    * within the request handler and from elsewhere in the application
    */
   if (0 != pthread_mutex_init(&conn->mutex, &pthread_mutex_attr)) {
      mg_free(conn->buf);
      mg_cry_internal(fc(ctx), "%s", "Cannot create mutex");
      return NULL;
   }

#if defined(USE_SERVER_STATS)
   conn->conn_state = 1; /* not consumed */
#endif

#if defined(ALTERNATIVE_QUEUE)
   while ((ctx->stop_flag == 0)
          && consume_socket(ctx, &conn->client, conn->thread_index)) {
#else
   /* Call consume_socket() even when ctx->stop_flag > 0, to let it
    * signal sq_empty condvar to wake up the master waiting in
    * produce_socket() */
   while (consume_socket(ctx, &conn->client, conn->thread_index)) {
#endif

      conn->conn_birth_time = time(NULL);

/* Fill in IP, port info early so even if SSL setup below fails,
 * error handler would have the corresponding info.
 * Thanks to Johannes Winkelmann for the patch.
 */
#if defined(USE_IPV6)
      if (conn->client.rsa.sa.sa_family == AF_INET6) {
         conn->request_info.remote_port =
             ntohs(conn->client.rsa.sin6.sin6_port);
      } else
#endif
      {
         conn->request_info.remote_port =
             ntohs(conn->client.rsa.sin.sin_port);
      }

      sockaddr_to_string(conn->request_info.remote_addr,
                         sizeof(conn->request_info.remote_addr),
                         &conn->client.rsa);

      DEBUG_TRACE("Start processing connection from %s",
                  conn->request_info.remote_addr);

      conn->request_info.is_ssl = conn->client.is_ssl;

      if (conn->client.is_ssl) {
#if !defined(NO_SSL)
         /* HTTPS connection */
         if (sslize(conn,
                    conn->dom_ctx->ssl_ctx,
                    SSL_accept,
                    &(conn->phys_ctx->stop_flag),
                    NULL)) {
            /* conn->dom_ctx is set in get_request */

            /* Get SSL client certificate information (if set) */
            ssl_get_client_cert_info(conn);

            /* process HTTPS connection */
            process_new_connection(conn);

            /* Free client certificate info */
            if (conn->request_info.client_cert) {
               mg_free((void *)(conn->request_info.client_cert->subject));
               mg_free((void *)(conn->request_info.client_cert->issuer));
               mg_free((void *)(conn->request_info.client_cert->serial));
               mg_free((void *)(conn->request_info.client_cert->finger));
               /* Free certificate memory */
               X509_free(
                   (X509 *)conn->request_info.client_cert->peer_cert);
               conn->request_info.client_cert->peer_cert = 0;
               conn->request_info.client_cert->subject = 0;
               conn->request_info.client_cert->issuer = 0;
               conn->request_info.client_cert->serial = 0;
               conn->request_info.client_cert->finger = 0;
               mg_free(conn->request_info.client_cert);
               conn->request_info.client_cert = 0;
            }
         } else {
            /* make sure the connection is cleaned up on SSL failure */
            close_connection(conn);
         }
#endif
      } else {
         /* process HTTP connection */
         process_new_connection(conn);
      }

      DEBUG_TRACE("%s", "Connection closed");
   }


   pthread_setspecific(sTlsKey, NULL);
#if defined(_WIN32)
   CloseHandle(tls.pthread_cond_helper_mutex);
#endif
   pthread_mutex_destroy(&conn->mutex);

   /* Free the request buffer. */
   conn->buf_size = 0;
   mg_free(conn->buf);
   conn->buf = NULL;

#if defined(USE_SERVER_STATS)
   conn->conn_state = 9; /* done */
#endif

   DEBUG_TRACE("%s", "exiting");
   return NULL;
}


/* Threads have different return types on Windows and Unix. */
#if defined(_WIN32)
static unsigned __stdcall worker_thread(void *thread_func_param)
{
   struct worker_thread_args *pwta =
       (struct worker_thread_args *)thread_func_param;
   worker_thread_run(pwta);
   mg_free(thread_func_param);
   return 0;
}
#else
static void *
worker_thread(void *thread_func_param)
{
   struct worker_thread_args *pwta =
       (struct worker_thread_args *)thread_func_param;
   struct sigaction sa;

   /* Ignore SIGPIPE */
   memset(&sa, 0, sizeof(sa));
   sa.sa_handler = SIG_IGN;
   sigaction(SIGPIPE, &sa, NULL);

   worker_thread_run(pwta);
   mg_free(thread_func_param);
   return NULL;
}
#endif /* _WIN32 */


/* This is an internal function, thus all arguments are expected to be
 * valid - a NULL check is not required. */
static void
accept_new_connection(const struct socket *listener, struct mg_context *ctx)
{
   struct socket so;
   char src_addr[IP_ADDR_STR_LEN];
   socklen_t len = sizeof(so.rsa);
   int on = 1;

   if ((so.sock = accept(listener->sock, &so.rsa.sa, &len))
       == INVALID_SOCKET) {
   } else if (!check_acl(ctx, ntohl(*(uint32_t *)&so.rsa.sin.sin_addr))) {
      sockaddr_to_string(src_addr, sizeof(src_addr), &so.rsa);
      mg_cry_internal(fc(ctx),
                      "%s: %s is not allowed to connect",
                      __func__,
                      src_addr);
      closesocket(so.sock);
   } else {
      /* Put so socket structure into the queue */
      DEBUG_TRACE("Accepted socket %d", (int)so.sock);
      set_close_on_exec(so.sock, fc(ctx));
      so.is_ssl = listener->is_ssl;
      so.ssl_redir = listener->ssl_redir;
      if (getsockname(so.sock, &so.lsa.sa, &len) != 0) {
         mg_cry_internal(fc(ctx),
                         "%s: getsockname() failed: %s",
                         __func__,
                         strerror(ERRNO));
      }

      /* Set TCP keep-alive. This is needed because if HTTP-level
       * keep-alive
       * is enabled, and client resets the connection, server won't get
       * TCP FIN or RST and will keep the connection open forever. With
       * TCP keep-alive, next keep-alive handshake will figure out that
       * the client is down and will close the server end.
       * Thanks to Igor Klopov who suggested the patch. */
      if (setsockopt(so.sock,
                     SOL_SOCKET,
                     SO_KEEPALIVE,
                     (SOCK_OPT_TYPE)&on,
                     sizeof(on))
          != 0) {
         mg_cry_internal(
             fc(ctx),
             "%s: setsockopt(SOL_SOCKET SO_KEEPALIVE) failed: %s",
             __func__,
             strerror(ERRNO));
      }

      /* Disable TCP Nagle's algorithm. Normally TCP packets are coalesced
       * to effectively fill up the underlying IP packet payload and
       * reduce the overhead of sending lots of small buffers. However
       * this hurts the server's throughput (ie. operations per second)
       * when HTTP 1.1 persistent connections are used and the responses
       * are relatively small (eg. less than 1400 bytes).
       */
      if ((ctx->dd.config[CONFIG_TCP_NODELAY] != NULL)
          && (!strcmp(ctx->dd.config[CONFIG_TCP_NODELAY], "1"))) {
         if (set_tcp_nodelay(so.sock, 1) != 0) {
            mg_cry_internal(
                fc(ctx),
                "%s: setsockopt(IPPROTO_TCP TCP_NODELAY) failed: %s",
                __func__,
                strerror(ERRNO));
         }
      }

      /* We are using non-blocking sockets. Thus, the
       * set_sock_timeout(so.sock, timeout);
       * call is no longer required. */

      /* The "non blocking" property should already be
       * inherited from the parent socket. Set it for
       * non-compliant socket implementations. */
      set_non_blocking_mode(so.sock);

      so.in_use = 0;
      produce_socket(ctx, &so);
   }
}


static void
master_thread_run(void *thread_func_param)
{
   struct mg_context *ctx = (struct mg_context *)thread_func_param;
   struct mg_workerTLS tls;
   struct pollfd *pfd;
   unsigned int i;
   unsigned int workerthreadcount;

   if (!ctx) {
      return;
   }

   mg_set_thread_name("master");

/* Increase priority of the master thread */
#if defined(_WIN32)
   SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_ABOVE_NORMAL);
#elif defined(USE_MASTER_THREAD_PRIORITY)
   int min_prio = sched_get_priority_min(SCHED_RR);
   int max_prio = sched_get_priority_max(SCHED_RR);
   if ((min_prio >= 0) && (max_prio >= 0)
       && ((USE_MASTER_THREAD_PRIORITY) <= max_prio)
       && ((USE_MASTER_THREAD_PRIORITY) >= min_prio)) {
      struct sched_param sched_param = {0};
      sched_param.sched_priority = (USE_MASTER_THREAD_PRIORITY);
      pthread_setschedparam(pthread_self(), SCHED_RR, &sched_param);
   }
#endif

/* Initialize thread local storage */
#if defined(_WIN32)
   tls.pthread_cond_helper_mutex = CreateEvent(NULL, FALSE, FALSE, NULL);
#endif
   tls.is_master = 1;
   pthread_setspecific(sTlsKey, &tls);

   if (ctx->callbacks.init_thread) {
      /* Callback for the master thread (type 0) */
      ctx->callbacks.init_thread(ctx, 0);
   }

   /* Server starts *now* */
   ctx->start_time = time(NULL);

   /* Start the server */
   pfd = ctx->listening_socket_fds;
   while (ctx->stop_flag == 0) {
      for (i = 0; i < ctx->num_listening_sockets; i++) {
         pfd[i].fd = ctx->listening_sockets[i].sock;
         pfd[i].events = POLLIN;
      }

      if (poll(pfd, ctx->num_listening_sockets, 200) > 0) {
         for (i = 0; i < ctx->num_listening_sockets; i++) {
            /* NOTE(lsm): on QNX, poll() returns POLLRDNORM after the
             * successful poll, and POLLIN is defined as
             * (POLLRDNORM | POLLRDBAND)
             * Therefore, we're checking pfd[i].revents & POLLIN, not
             * pfd[i].revents == POLLIN. */
            if ((ctx->stop_flag == 0) && (pfd[i].revents & POLLIN)) {
               accept_new_connection(&ctx->listening_sockets[i], ctx);
            }
         }
      }
   }

   /* Here stop_flag is 1 - Initiate shutdown. */
   DEBUG_TRACE("%s", "stopping workers");

   /* Stop signal received: somebody called mg_stop. Quit. */
   close_all_listening_sockets(ctx);

   /* Wakeup workers that are waiting for connections to handle. */
   (void)pthread_mutex_lock(&ctx->thread_mutex);
#if defined(ALTERNATIVE_QUEUE)
   for (i = 0; i < ctx->cfg_worker_threads; i++) {
      event_signal(ctx->client_wait_events[i]);

      /* Since we know all sockets, we can shutdown the connections. */
      if (ctx->client_socks[i].in_use) {
         shutdown(ctx->client_socks[i].sock, SHUTDOWN_BOTH);
      }
   }
#else
   pthread_cond_broadcast(&ctx->sq_full);
#endif
   (void)pthread_mutex_unlock(&ctx->thread_mutex);

   /* Join all worker threads to avoid leaking threads. */
   workerthreadcount = ctx->cfg_worker_threads;
   for (i = 0; i < workerthreadcount; i++) {
      if (ctx->worker_threadids[i] != 0) {
         mg_join_thread(ctx->worker_threadids[i]);
      }
   }

#if defined(USE_LUA)
   /* Free Lua state of lua background task */
   if (ctx->lua_background_state) {
      lua_State *lstate = (lua_State *)ctx->lua_background_state;
      lua_getglobal(lstate, LUABACKGROUNDPARAMS);
      if (lua_istable(lstate, -1)) {
         reg_boolean(lstate, "shutdown", 1);
         lua_pop(lstate, 1);
         mg_sleep(2);
      }
      lua_close(lstate);
      ctx->lua_background_state = 0;
   }
#endif

   DEBUG_TRACE("%s", "exiting");

#if defined(_WIN32)
   CloseHandle(tls.pthread_cond_helper_mutex);
#endif
   pthread_setspecific(sTlsKey, NULL);

   /* Signal mg_stop() that we're done.
    * WARNING: This must be the very last thing this
    * thread does, as ctx becomes invalid after this line. */
   ctx->stop_flag = 2;
}


/* Threads have different return types on Windows and Unix. */
#if defined(_WIN32)
static unsigned __stdcall master_thread(void *thread_func_param)
{
   master_thread_run(thread_func_param);
   return 0;
}
#else
static void *
master_thread(void *thread_func_param)
{
   struct sigaction sa;

   /* Ignore SIGPIPE */
   memset(&sa, 0, sizeof(sa));
   sa.sa_handler = SIG_IGN;
   sigaction(SIGPIPE, &sa, NULL);

   master_thread_run(thread_func_param);
   return NULL;
}
#endif /* _WIN32 */


static void
free_context(struct mg_context *ctx)
{
   int i;
   struct mg_handler_info *tmp_rh;

   if (ctx == NULL) {
      return;
   }

   if (ctx->callbacks.exit_context) {
      ctx->callbacks.exit_context(ctx);
   }

   /* All threads exited, no sync is needed. Destroy thread mutex and
    * condvars
    */
   (void)pthread_mutex_destroy(&ctx->thread_mutex);
#if defined(ALTERNATIVE_QUEUE)
   mg_free(ctx->client_socks);
   for (i = 0; (unsigned)i < ctx->cfg_worker_threads; i++) {
      event_destroy(ctx->client_wait_events[i]);
   }
   mg_free(ctx->client_wait_events);
#else
   (void)pthread_cond_destroy(&ctx->sq_empty);
   (void)pthread_cond_destroy(&ctx->sq_full);
#endif

   /* Destroy other context global data structures mutex */
   (void)pthread_mutex_destroy(&ctx->nonce_mutex);

#if defined(USE_TIMERS)
   timers_exit(ctx);
#endif

   /* Deallocate config parameters */
   for (i = 0; i < NUM_OPTIONS; i++) {
      if (ctx->dd.config[i] != NULL) {
#if defined(_MSC_VER)
#pragma warning(suppress : 6001)
#endif
         mg_free(ctx->dd.config[i]);
      }
   }

   /* Deallocate request handlers */
   while (ctx->dd.handlers) {
      tmp_rh = ctx->dd.handlers;
      ctx->dd.handlers = tmp_rh->next;
      if (tmp_rh->handler_type == REQUEST_HANDLER) {
         pthread_cond_destroy(&tmp_rh->refcount_cond);
         pthread_mutex_destroy(&tmp_rh->refcount_mutex);
      }
      mg_free(tmp_rh->uri);
      mg_free(tmp_rh);
   }

#if !defined(NO_SSL)
   /* Deallocate SSL context */
   if (ctx->dd.ssl_ctx != NULL) {
      void *ssl_ctx = (void *)ctx->dd.ssl_ctx;
      int callback_ret =
          (ctx->callbacks.external_ssl_ctx == NULL)
              ? 0
              : (ctx->callbacks.external_ssl_ctx(&ssl_ctx, ctx->user_data));

      if (callback_ret == 0) {
         SSL_CTX_free(ctx->dd.ssl_ctx);
      }
      /* else: ignore error and ommit SSL_CTX_free in case
       * callback_ret is 1 */
   }
#endif /* !NO_SSL */

   /* Deallocate worker thread ID array */
   if (ctx->worker_threadids != NULL) {
      mg_free(ctx->worker_threadids);
   }

   /* Deallocate worker thread ID array */
   if (ctx->worker_connections != NULL) {
      mg_free(ctx->worker_connections);
   }

   /* deallocate system name string */
   mg_free(ctx->systemName);

   /* Deallocate context itself */
   mg_free(ctx);
}


void
mg_stop(struct mg_context *ctx)
{
   pthread_t mt;
   if (!ctx) {
      return;
   }

   /* We don't use a lock here. Calling mg_stop with the same ctx from
    * two threads is not allowed. */
   mt = ctx->masterthreadid;
   if (mt == 0) {
      return;
   }

   ctx->masterthreadid = 0;

   /* Set stop flag, so all threads know they have to exit. */
   ctx->stop_flag = 1;

   /* Wait until everything has stopped. */
   while (ctx->stop_flag != 2) {
      (void)mg_sleep(10);
   }

   mg_join_thread(mt);
   free_context(ctx);

#if defined(_WIN32)
   (void)WSACleanup();
#endif /* _WIN32 */
}


static void
get_system_name(char **sysName)
{
#if defined(_WIN32)
#if !defined(__SYMBIAN32__)
#if defined(_WIN32_WCE)
   *sysName = mg_strdup("WinCE");
#else
   char name[128];
   DWORD dwVersion = 0;
   DWORD dwMajorVersion = 0;
   DWORD dwMinorVersion = 0;
   DWORD dwBuild = 0;
   BOOL wowRet, isWoW = FALSE;

#if defined(_MSC_VER)
#pragma warning(push)
/* GetVersion was declared deprecated */
#pragma warning(disable : 4996)
#endif
   dwVersion = GetVersion();
#if defined(_MSC_VER)
#pragma warning(pop)
#endif

   dwMajorVersion = (DWORD)(LOBYTE(LOWORD(dwVersion)));
   dwMinorVersion = (DWORD)(HIBYTE(LOWORD(dwVersion)));
   dwBuild = ((dwVersion < 0x80000000) ? (DWORD)(HIWORD(dwVersion)) : 0);
   (void)dwBuild;

   wowRet = IsWow64Process(GetCurrentProcess(), &isWoW);

   sprintf(name,
           "Windows %u.%u%s",
           (unsigned)dwMajorVersion,
           (unsigned)dwMinorVersion,
           (wowRet ? (isWoW ? " (WoW64)" : "") : " (?)"));

   *sysName = mg_strdup(name);
#endif
#else
   *sysName = mg_strdup("Symbian");
#endif
#else
   struct utsname name;
   memset(&name, 0, sizeof(name));
   uname(&name);
   *sysName = mg_strdup(name.sysname);
#endif
}


struct mg_context *
mg_start(const struct mg_callbacks *callbacks,
         void *user_data,
         const char **options)
{
   struct mg_context *ctx;
   const char *name, *value, *default_value;
   int idx, ok, workerthreadcount;
   unsigned int i;
   int itmp;
   void (*exit_callback)(const struct mg_context *ctx) = 0;

   struct mg_workerTLS tls;

#if defined(_WIN32)
   WSADATA data;
   WSAStartup(MAKEWORD(2, 2), &data);
#endif /* _WIN32  */

   /* Allocate context and initialize reasonable general case defaults. */
   if ((ctx = (struct mg_context *)mg_calloc(1, sizeof(*ctx))) == NULL) {
      return NULL;
   }

   /* Random number generator will initialize at the first call */
   ctx->dd.auth_nonce_mask =
       (uint64_t)get_random() ^ (uint64_t)(ptrdiff_t)(options);

   if (mg_init_library_called == 0) {
      /* Legacy INIT, if mg_start is called without mg_init_library.
       * Note: This may cause a memory leak */
      const char *ports_option =
          config_options[LISTENING_PORTS].default_value;

      if (options) {
         const char **run_options = options;
         const char *optname = config_options[LISTENING_PORTS].name;

         /* Try to find the "listening_ports" option */
         while (*run_options) {
            if (!strcmp(*run_options, optname)) {
               ports_option = run_options[1];
            }
            run_options += 2;
         }
      }

      if (is_ssl_port_used(ports_option)) {
         /* Initialize with SSL support */
         mg_init_library(MG_FEATURES_TLS);
      } else {
         /* Initialize without SSL support */
         mg_init_library(MG_FEATURES_DEFAULT);
      }
   }

   tls.is_master = -1;
   tls.thread_idx = (unsigned)mg_atomic_inc(&thread_idx_max);
#if defined(_WIN32)
   tls.pthread_cond_helper_mutex = NULL;
#endif
   pthread_setspecific(sTlsKey, &tls);

   ok = (0 == pthread_mutex_init(&ctx->thread_mutex, &pthread_mutex_attr));
#if !defined(ALTERNATIVE_QUEUE)
   ok &= (0 == pthread_cond_init(&ctx->sq_empty, NULL));
   ok &= (0 == pthread_cond_init(&ctx->sq_full, NULL));
#endif
   ok &= (0 == pthread_mutex_init(&ctx->nonce_mutex, &pthread_mutex_attr));
   if (!ok) {
      /* Fatal error - abort start. However, this situation should never
       * occur in practice. */
      mg_cry_internal(fc(ctx),
                      "%s",
                      "Cannot initialize thread synchronization objects");
      mg_free(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }

   if (callbacks) {
      ctx->callbacks = *callbacks;
      exit_callback = callbacks->exit_context;
      ctx->callbacks.exit_context = 0;
   }
   ctx->user_data = user_data;
   ctx->dd.handlers = NULL;
   ctx->dd.next = NULL;

#if defined(USE_LUA) && defined(USE_WEBSOCKET)
   ctx->dd.shared_lua_websockets = NULL;
#endif

   /* Store options */
   while (options && (name = *options++) != NULL) {
      if ((idx = get_option_index(name)) == -1) {
         mg_cry_internal(fc(ctx), "Invalid option: %s", name);
         free_context(ctx);
         pthread_setspecific(sTlsKey, NULL);
         return NULL;
      } else if ((value = *options++) == NULL) {
         mg_cry_internal(fc(ctx), "%s: option value cannot be NULL", name);
         free_context(ctx);
         pthread_setspecific(sTlsKey, NULL);
         return NULL;
      }
      if (ctx->dd.config[idx] != NULL) {
         mg_cry_internal(fc(ctx), "warning: %s: duplicate option", name);
         mg_free(ctx->dd.config[idx]);
      }
      ctx->dd.config[idx] = mg_strdup_ctx(value, ctx);
      DEBUG_TRACE("[%s] -> [%s]", name, value);
   }

   /* Set default value if needed */
   for (i = 0; config_options[i].name != NULL; i++) {
      default_value = config_options[i].default_value;
      if ((ctx->dd.config[i] == NULL) && (default_value != NULL)) {
         ctx->dd.config[i] = mg_strdup_ctx(default_value, ctx);
      }
   }

   /* Request size option */
   itmp = atoi(ctx->dd.config[MAX_REQUEST_SIZE]);
   if (itmp < 1024) {
      mg_cry_internal(fc(ctx), "%s", "max_request_size too small");
      free_context(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }
   ctx->max_request_size = (unsigned)itmp;

   /* Worker thread count option */
   workerthreadcount = atoi(ctx->dd.config[NUM_THREADS]);

   if (workerthreadcount > MAX_WORKER_THREADS) {
      mg_cry_internal(fc(ctx), "%s", "Too many worker threads");
      free_context(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }

   if (workerthreadcount <= 0) {
      mg_cry_internal(fc(ctx), "%s", "Invalid number of worker threads");
      free_context(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }

/* Document root */
#if defined(NO_FILES)
   if (ctx->dd.config[DOCUMENT_ROOT] != NULL) {
      mg_cry_internal(fc(ctx), "%s", "Document root must not be set");
      free_context(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }
#endif

   get_system_name(&ctx->systemName);

#if defined(USE_LUA)
   /* If a Lua background script has been configured, start it. */
   if (ctx->dd.config[LUA_BACKGROUND_SCRIPT] != NULL) {
      char ebuf[256];
      struct vec opt_vec;
      struct vec eq_vec;
      const char *sparams;
      lua_State *state = mg_prepare_lua_context_script(
          ctx->dd.config[LUA_BACKGROUND_SCRIPT], ctx, ebuf, sizeof(ebuf));
      if (!state) {
         mg_cry_internal(fc(ctx), "lua_background_script error: %s", ebuf);
         free_context(ctx);
         pthread_setspecific(sTlsKey, NULL);
         return NULL;
      }
      ctx->lua_background_state = (void *)state;

      lua_newtable(state);
      reg_boolean(state, "shutdown", 0);

      sparams = ctx->dd.config[LUA_BACKGROUND_SCRIPT_PARAMS];

      while ((sparams = next_option(sparams, &opt_vec, &eq_vec)) != NULL) {
         reg_llstring(
             state, opt_vec.ptr, opt_vec.len, eq_vec.ptr, eq_vec.len);
         if (mg_strncasecmp(sparams, opt_vec.ptr, opt_vec.len) == 0)
            break;
      }
      lua_setglobal(state, LUABACKGROUNDPARAMS);

   } else {
      ctx->lua_background_state = 0;
   }
#endif

   /* NOTE(lsm): order is important here. SSL certificates must
    * be initialized before listening ports. UID must be set last. */
   if (!set_gpass_option(ctx, NULL) ||
#if !defined(NO_SSL)
       !init_ssl_ctx(ctx, NULL) ||
#endif
       !set_ports_option(ctx) ||
#if !defined(_WIN32)
       !set_uid_option(ctx) ||
#endif
       !set_acl_option(ctx)) {
      free_context(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }

   ctx->cfg_worker_threads = ((unsigned int)(workerthreadcount));
   ctx->worker_threadids = (pthread_t *)mg_calloc_ctx(ctx->cfg_worker_threads,
                                                      sizeof(pthread_t),
                                                      ctx);

   if (ctx->worker_threadids == NULL) {
      mg_cry_internal(fc(ctx),
                      "%s",
                      "Not enough memory for worker thread ID array");
      free_context(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }
   ctx->worker_connections =
       (struct mg_connection *)mg_calloc_ctx(ctx->cfg_worker_threads,
                                             sizeof(struct mg_connection),
                                             ctx);
   if (ctx->worker_connections == NULL) {
      mg_cry_internal(fc(ctx),
                      "%s",
                      "Not enough memory for worker thread connection array");
      free_context(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }


#if defined(ALTERNATIVE_QUEUE)
   ctx->client_wait_events =
       (void **)mg_calloc_ctx(sizeof(ctx->client_wait_events[0]),
                              ctx->cfg_worker_threads,
                              ctx);
   if (ctx->client_wait_events == NULL) {
      mg_cry_internal(fc(ctx),
                      "%s",
                      "Not enough memory for worker event array");
      mg_free(ctx->worker_threadids);
      free_context(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }

   ctx->client_socks =
       (struct socket *)mg_calloc_ctx(sizeof(ctx->client_socks[0]),
                                      ctx->cfg_worker_threads,
                                      ctx);
   if (ctx->client_socks == NULL) {
      mg_cry_internal(fc(ctx),
                      "%s",
                      "Not enough memory for worker socket array");
      mg_free(ctx->client_wait_events);
      mg_free(ctx->worker_threadids);
      free_context(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }

   for (i = 0; (unsigned)i < ctx->cfg_worker_threads; i++) {
      ctx->client_wait_events[i] = event_create();
      if (ctx->client_wait_events[i] == 0) {
         mg_cry_internal(fc(ctx), "Error creating worker event %i", i);
         while (i > 0) {
            i--;
            event_destroy(ctx->client_wait_events[i]);
         }
         mg_free(ctx->client_socks);
         mg_free(ctx->client_wait_events);
         mg_free(ctx->worker_threadids);
         free_context(ctx);
         pthread_setspecific(sTlsKey, NULL);
         return NULL;
      }
   }
#endif


#if defined(USE_TIMERS)
   if (timers_init(ctx) != 0) {
      mg_cry_internal(fc(ctx), "%s", "Error creating timers");
      free_context(ctx);
      pthread_setspecific(sTlsKey, NULL);
      return NULL;
   }
#endif

   /* Context has been created - init user libraries */
   if (ctx->callbacks.init_context) {
      ctx->callbacks.init_context(ctx);
   }
   ctx->callbacks.exit_context = exit_callback;
   ctx->context_type = CONTEXT_SERVER; /* server context */

   /* Start master (listening) thread */
   mg_start_thread_with_id(master_thread, ctx, &ctx->masterthreadid);

   /* Start worker threads */
   for (i = 0; i < ctx->cfg_worker_threads; i++) {
      struct worker_thread_args *wta = (struct worker_thread_args *)
          mg_malloc_ctx(sizeof(struct worker_thread_args), ctx);
      if (wta) {
         wta->ctx = ctx;
         wta->index = (int)i;
      }

      if ((wta == NULL)
          || (mg_start_thread_with_id(worker_thread,
                                      wta,
                                      &ctx->worker_threadids[i])
              != 0)) {

         /* thread was not created */
         if (wta != NULL) {
            mg_free(wta);
         }

         if (i > 0) {
            mg_cry_internal(fc(ctx),
                            "Cannot start worker thread %i: error %ld",
                            i + 1,
                            (long)ERRNO);
         } else {
            mg_cry_internal(fc(ctx),
                            "Cannot create threads: error %ld",
                            (long)ERRNO);
            free_context(ctx);
            pthread_setspecific(sTlsKey, NULL);
            return NULL;
         }
         break;
      }
   }

   pthread_setspecific(sTlsKey, NULL);
   return ctx;
}


#if defined(MG_EXPERIMENTAL_INTERFACES)
/* Add an additional domain to an already running web server. */
int
mg_start_domain(struct mg_context *ctx, const char **options)
{
   const char *name;
   const char *value;
   const char *default_value;
   struct mg_domain_context *new_dom;
   struct mg_domain_context *dom;
   int idx, i;

   if ((ctx == NULL) || (ctx->stop_flag != 0) || (options == NULL)) {
      return -1;
   }

   new_dom = (struct mg_domain_context *)
       mg_calloc_ctx(1, sizeof(struct mg_domain_context), ctx);

   if (!new_dom) {
      /* Out of memory */
      return -6;
   }

   /* Store options - TODO: unite duplicate code */
   while (options && (name = *options++) != NULL) {
      if ((idx = get_option_index(name)) == -1) {
         mg_cry_internal(fc(ctx), "Invalid option: %s", name);
         mg_free(new_dom);
         return -2;
      } else if ((value = *options++) == NULL) {
         mg_cry_internal(fc(ctx), "%s: option value cannot be NULL", name);
         mg_free(new_dom);
         return -2;
      }
      if (new_dom->config[idx] != NULL) {
         mg_cry_internal(fc(ctx), "warning: %s: duplicate option", name);
         mg_free(new_dom->config[idx]);
      }
      new_dom->config[idx] = mg_strdup_ctx(value, ctx);
      DEBUG_TRACE("[%s] -> [%s]", name, value);
   }

   /* Authentication domain is mandatory */
   /* TODO: Maybe use a new option hostname? */
   if (!new_dom->config[AUTHENTICATION_DOMAIN]) {
      mg_cry_internal(fc(ctx), "%s", "authentication domain required");
      mg_free(new_dom);
      return -4;
   }

   /* Set default value if needed. Take the config value from
    * ctx as a default value. */
   for (i = 0; config_options[i].name != NULL; i++) {
      default_value = ctx->dd.config[i];
      if ((new_dom->config[i] == NULL) && (default_value != NULL)) {
         new_dom->config[i] = mg_strdup_ctx(default_value, ctx);
      }
   }

   new_dom->handlers = NULL;
   new_dom->next = NULL;
   new_dom->nonce_count = 0;
   new_dom->auth_nonce_mask =
       (uint64_t)get_random() ^ ((uint64_t)get_random() << 31);

#if defined(USE_LUA) && defined(USE_WEBSOCKET)
   new_dom->shared_lua_websockets = NULL;
#endif

   if (!init_ssl_ctx(ctx, new_dom)) {
      /* Init SSL failed */
      mg_free(new_dom);
      return -3;
   }

   /* Add element to linked list. */
   mg_lock_context(ctx);

   idx = 0;
   dom = &(ctx->dd);
   for (;;) {
      if (!strcasecmp(new_dom->config[AUTHENTICATION_DOMAIN],
                      dom->config[AUTHENTICATION_DOMAIN])) {
         /* Domain collision */
         mg_cry_internal(fc(ctx),
                         "domain %s already in use",
                         new_dom->config[AUTHENTICATION_DOMAIN]);
         mg_free(new_dom);
         return -5;
      }

      /* Count number of domains */
      idx++;

      if (dom->next == NULL) {
         dom->next = new_dom;
         break;
      }
      dom = dom->next;
   }

   mg_unlock_context(ctx);

   /* Return domain number */
   return idx;
}
#endif


/* Feature check API function */
unsigned
mg_check_feature(unsigned feature)
{
   static const unsigned feature_set = 0
/* Set bits for available features according to API documentation.
 * This bit mask is created at compile time, according to the active
 * preprocessor defines. It is a single const value at runtime. */
#if !defined(NO_FILES)
                                       | MG_FEATURES_FILES
#endif
#if !defined(NO_SSL)
                                       | MG_FEATURES_SSL
#endif
#if !defined(NO_CGI)
                                       | MG_FEATURES_CGI
#endif
#if defined(USE_IPV6)
                                       | MG_FEATURES_IPV6
#endif
#if defined(USE_WEBSOCKET)
                                       | MG_FEATURES_WEBSOCKET
#endif
#if defined(USE_LUA)
                                       | MG_FEATURES_LUA
#endif
#if defined(USE_DUKTAPE)
                                       | MG_FEATURES_SSJS
#endif
#if !defined(NO_CACHING)
                                       | MG_FEATURES_CACHE
#endif
#if defined(USE_SERVER_STATS)
                                       | MG_FEATURES_STATS
#endif
#if defined(USE_ZLIB)
                                       | MG_FEATURES_COMPRESSION
#endif

/* Set some extra bits not defined in the API documentation.
 * These bits may change without further notice. */
#if defined(MG_LEGACY_INTERFACE)
                                       | 0x00008000u
#endif
#if defined(MG_EXPERIMENTAL_INTERFACES)
                                       | 0x00004000u
#endif
#if defined(MEMORY_DEBUGGING)
                                       | 0x00001000u
#endif
#if defined(USE_TIMERS)
                                       | 0x00020000u
#endif
#if !defined(NO_NONCE_CHECK)
                                       | 0x00040000u
#endif
#if !defined(NO_POPEN)
                                       | 0x00080000u
#endif
       ;
   return (feature & feature_set);
}


/* strcat with additional NULL check to avoid clang scan-build warning. */
#define strcat0(a, b)                                                          \
   {                                                                          \
      if ((a != NULL) && (b != NULL)) {                                      \
         strcat(a, b);                                                      \
      }                                                                      \
   }


/* Get system information. It can be printed or stored by the caller.
 * Return the size of available information. */
static int
mg_get_system_info_impl(char *buffer, int buflen)
{
   char block[256];
   int system_info_length = 0;

#if defined(_WIN32)
   const char *eol = "\r\n";
#else
   const char *eol = "\n";
#endif

   const char *eoobj = "}";
   int reserved_len = (int)strlen(eoobj) + (int)strlen(eol);

   if ((buffer == NULL) || (buflen < 1)) {
      buflen = 0;
   } else {
      *buffer = 0;
   }

   mg_snprintf(NULL, NULL, block, sizeof(block), "{%s", eol);
   system_info_length += (int)strlen(block);
   if (system_info_length < buflen) {
      strcat0(buffer, block);
   }

   /* Server version */
   {
      const char *version = mg_version();
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"version\" : \"%s\",%s",
                  version,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
   }

   /* System info */
   {
#if defined(_WIN32)
      DWORD dwVersion = 0;
      DWORD dwMajorVersion = 0;
      DWORD dwMinorVersion = 0;
      SYSTEM_INFO si;

      GetSystemInfo(&si);

#if defined(_MSC_VER)
#pragma warning(push)
/* GetVersion was declared deprecated */
#pragma warning(disable : 4996)
#endif
      dwVersion = GetVersion();
#if defined(_MSC_VER)
#pragma warning(pop)
#endif

      dwMajorVersion = (DWORD)(LOBYTE(LOWORD(dwVersion)));
      dwMinorVersion = (DWORD)(HIBYTE(LOWORD(dwVersion)));

      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"os\" : \"Windows %u.%u\",%s",
                  (unsigned)dwMajorVersion,
                  (unsigned)dwMinorVersion,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }

      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"cpu\" : \"type %u, cores %u, mask %x\",%s",
                  (unsigned)si.wProcessorArchitecture,
                  (unsigned)si.dwNumberOfProcessors,
                  (unsigned)si.dwActiveProcessorMask,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#else
      struct utsname name;
      memset(&name, 0, sizeof(name));
      uname(&name);

      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"os\" : \"%s %s (%s) - %s\",%s",
                  name.sysname,
                  name.version,
                  name.release,
                  name.machine,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#endif
   }

   /* Features */
   {
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"features\" : %lu,%s"
                  "\"feature_list\" : \"Server:%s%s%s%s%s%s%s%s%s\",%s",
                  (unsigned long)mg_check_feature(0xFFFFFFFFu),
                  eol,
                  mg_check_feature(MG_FEATURES_FILES) ? " Files" : "",
                  mg_check_feature(MG_FEATURES_SSL) ? " HTTPS" : "",
                  mg_check_feature(MG_FEATURES_CGI) ? " CGI" : "",
                  mg_check_feature(MG_FEATURES_IPV6) ? " IPv6" : "",
                  mg_check_feature(MG_FEATURES_WEBSOCKET) ? " WebSockets"
                                                          : "",
                  mg_check_feature(MG_FEATURES_LUA) ? " Lua" : "",
                  mg_check_feature(MG_FEATURES_SSJS) ? " JavaScript" : "",
                  mg_check_feature(MG_FEATURES_CACHE) ? " Cache" : "",
                  mg_check_feature(MG_FEATURES_STATS) ? " Stats" : "",
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }

#if defined(USE_LUA)
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"lua_version\" : \"%u (%s)\",%s",
                  (unsigned)LUA_VERSION_NUM,
                  LUA_RELEASE,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#endif
#if defined(USE_DUKTAPE)
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"javascript\" : \"Duktape %u.%u.%u\",%s",
                  (unsigned)DUK_VERSION / 10000,
                  ((unsigned)DUK_VERSION / 100) % 100,
                  (unsigned)DUK_VERSION % 100,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#endif
   }

   /* Build date */
   {
#if defined(GCC_DIAGNOSTIC)
#if GCC_VERSION >= 50000
#pragma GCC diagnostic push
/* Disable bogus compiler warning -Wdate-time */
#pragma GCC diagnostic ignored "-Wdate-time"
#endif
#endif
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"build\" : \"%s\",%s",
                  __DATE__,
                  eol);

#if defined(GCC_DIAGNOSTIC)
#if GCC_VERSION >= 50000
#pragma GCC diagnostic pop
#endif
#endif

      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
   }


   /* Compiler information */
   /* http://sourceforge.net/p/predef/wiki/Compilers/ */
   {
#if defined(_MSC_VER)
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"compiler\" : \"MSC: %u (%u)\",%s",
                  (unsigned)_MSC_VER,
                  (unsigned)_MSC_FULL_VER,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#elif defined(__MINGW64__)
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"compiler\" : \"MinGW64: %u.%u\",%s",
                  (unsigned)__MINGW64_VERSION_MAJOR,
                  (unsigned)__MINGW64_VERSION_MINOR,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"compiler\" : \"MinGW32: %u.%u\",%s",
                  (unsigned)__MINGW32_MAJOR_VERSION,
                  (unsigned)__MINGW32_MINOR_VERSION,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#elif defined(__MINGW32__)
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"compiler\" : \"MinGW32: %u.%u\",%s",
                  (unsigned)__MINGW32_MAJOR_VERSION,
                  (unsigned)__MINGW32_MINOR_VERSION,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#elif defined(__clang__)
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"compiler\" : \"clang: %u.%u.%u (%s)\",%s",
                  __clang_major__,
                  __clang_minor__,
                  __clang_patchlevel__,
                  __clang_version__,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#elif defined(__GNUC__)
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"compiler\" : \"gcc: %u.%u.%u\",%s",
                  (unsigned)__GNUC__,
                  (unsigned)__GNUC_MINOR__,
                  (unsigned)__GNUC_PATCHLEVEL__,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#elif defined(__INTEL_COMPILER)
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"compiler\" : \"Intel C/C++: %u\",%s",
                  (unsigned)__INTEL_COMPILER,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#elif defined(__BORLANDC__)
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"compiler\" : \"Borland C: 0x%x\",%s",
                  (unsigned)__BORLANDC__,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#elif defined(__SUNPRO_C)
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"compiler\" : \"Solaris: 0x%x\",%s",
                  (unsigned)__SUNPRO_C,
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#else
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"compiler\" : \"other\",%s",
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
#endif
   }

   /* Determine 32/64 bit data mode.
    * see https://en.wikipedia.org/wiki/64-bit_computing */
   {
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"data_model\" : \"int:%u/%u/%u/%u, float:%u/%u/%u, "
                  "char:%u/%u, "
                  "ptr:%u, size:%u, time:%u\"%s",
                  (unsigned)sizeof(short),
                  (unsigned)sizeof(int),
                  (unsigned)sizeof(long),
                  (unsigned)sizeof(long long),
                  (unsigned)sizeof(float),
                  (unsigned)sizeof(double),
                  (unsigned)sizeof(long double),
                  (unsigned)sizeof(char),
                  (unsigned)sizeof(wchar_t),
                  (unsigned)sizeof(void *),
                  (unsigned)sizeof(size_t),
                  (unsigned)sizeof(time_t),
                  eol);
      system_info_length += (int)strlen(block);
      if (system_info_length < buflen) {
         strcat0(buffer, block);
      }
   }

   /* Terminate string */
   if ((buflen > 0) && buffer && buffer[0]) {
      if (system_info_length < buflen) {
         strcat0(buffer, eoobj);
         strcat0(buffer, eol);
      }
   }
   system_info_length += reserved_len;

   return system_info_length;
}


#if defined(USE_SERVER_STATS)
/* Get context information. It can be printed or stored by the caller.
 * Return the size of available information. */
static int
mg_get_context_info_impl(const struct mg_context *ctx, char *buffer, int buflen)

{
   char block[256];
   int context_info_length = 0;

#if defined(_WIN32)
   const char *eol = "\r\n";
#else
   const char *eol = "\n";
#endif
   struct mg_memory_stat *ms = get_memory_stat((struct mg_context *)ctx);

   const char *eoobj = "}";
   int reserved_len = (int)strlen(eoobj) + (int)strlen(eol);

   if ((buffer == NULL) || (buflen < 1)) {
      buflen = 0;
   } else {
      *buffer = 0;
   }

   mg_snprintf(NULL, NULL, block, sizeof(block), "{%s", eol);
   context_info_length += (int)strlen(block);
   if (context_info_length < buflen) {
      strcat0(buffer, block);
   }

   if (ms) { /* <-- should be always true */
      /* Memory information */
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"memory\" : {%s"
                  "\"blocks\" : %i,%s"
                  "\"used\" : %" INT64_FMT ",%s"
                  "\"maxUsed\" : %" INT64_FMT "%s"
                  "}%s%s",
                  eol,
                  ms->blockCount,
                  eol,
                  ms->totalMemUsed,
                  eol,
                  ms->maxMemUsed,
                  eol,
                  (ctx ? "," : ""),
                  eol);

      context_info_length += (int)strlen(block);
      if (context_info_length + reserved_len < buflen) {
         strcat0(buffer, block);
      }
   }

   if (ctx) {
      /* Declare all variables at begin of the block, to comply
       * with old C standards. */
      char start_time_str[64] = {0};
      char now_str[64] = {0};
      time_t start_time = ctx->start_time;
      time_t now = time(NULL);

      /* Connections information */
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"connections\" : {%s"
                  "\"active\" : %i,%s"
                  "\"maxActive\" : %i,%s"
                  "\"total\" : %" INT64_FMT "%s"
                  "},%s",
                  eol,
                  ctx->active_connections,
                  eol,
                  ctx->max_connections,
                  eol,
                  ctx->total_connections,
                  eol,
                  eol);

      context_info_length += (int)strlen(block);
      if (context_info_length + reserved_len < buflen) {
         strcat0(buffer, block);
      }

      /* Requests information */
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"requests\" : {%s"
                  "\"total\" : %" INT64_FMT "%s"
                  "},%s",
                  eol,
                  ctx->total_requests,
                  eol,
                  eol);

      context_info_length += (int)strlen(block);
      if (context_info_length + reserved_len < buflen) {
         strcat0(buffer, block);
      }

      /* Data information */
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"data\" : {%s"
                  "\"read\" : %" INT64_FMT "%s,"
                  "\"written\" : %" INT64_FMT "%s"
                  "},%s",
                  eol,
                  ctx->total_data_read,
                  eol,
                  ctx->total_data_written,
                  eol,
                  eol);

      context_info_length += (int)strlen(block);
      if (context_info_length + reserved_len < buflen) {
         strcat0(buffer, block);
      }

      /* Execution time information */
      gmt_time_string(start_time_str,
                      sizeof(start_time_str) - 1,
                      &start_time);
      gmt_time_string(now_str, sizeof(now_str) - 1, &now);

      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"time\" : {%s"
                  "\"uptime\" : %.0f,%s"
                  "\"start\" : \"%s\",%s"
                  "\"now\" : \"%s\"%s"
                  "}%s",
                  eol,
                  difftime(now, start_time),
                  eol,
                  start_time_str,
                  eol,
                  now_str,
                  eol,
                  eol);

      context_info_length += (int)strlen(block);
      if (context_info_length + reserved_len < buflen) {
         strcat0(buffer, block);
      }
   }

   /* Terminate string */
   if ((buflen > 0) && buffer && buffer[0]) {
      if (context_info_length < buflen) {
         strcat0(buffer, eoobj);
         strcat0(buffer, eol);
      }
   }
   context_info_length += reserved_len;

   return context_info_length;
}
#endif


#if defined(MG_EXPERIMENTAL_INTERFACES)
/* Get connection information. It can be printed or stored by the caller.
 * Return the size of available information. */
static int
mg_get_connection_info_impl(const struct mg_context *ctx,
                            int idx,
                            char *buffer,
                            int buflen)
{
   const struct mg_connection *conn;
   const struct mg_request_info *ri;
   char block[256];
   int connection_info_length = 0;
   int state = 0;
   const char *state_str = "unknown";

#if defined(_WIN32)
   const char *eol = "\r\n";
#else
   const char *eol = "\n";
#endif

   const char *eoobj = "}";
   int reserved_len = (int)strlen(eoobj) + (int)strlen(eol);

   if ((buffer == NULL) || (buflen < 1)) {
      buflen = 0;
   } else {
      *buffer = 0;
   }

   if ((ctx == NULL) || (idx < 0)) {
      /* Parameter error */
      return 0;
   }

   if ((unsigned)idx >= ctx->cfg_worker_threads) {
      /* Out of range */
      return 0;
   }

   /* Take connection [idx]. This connection is not locked in
    * any way, so some other thread might use it. */
   conn = (ctx->worker_connections) + idx;

   /* Initialize output string */
   mg_snprintf(NULL, NULL, block, sizeof(block), "{%s", eol);
   connection_info_length += (int)strlen(block);
   if (connection_info_length < buflen) {
      strcat0(buffer, block);
   }

   /* Init variables */
   ri = &(conn->request_info);

#if defined(USE_SERVER_STATS)
   state = conn->conn_state;

   /* State as string */
   switch (state) {
   case 0:
      state_str = "undefined";
      break;
   case 1:
      state_str = "not used";
      break;
   case 2:
      state_str = "init";
      break;
   case 3:
      state_str = "ready";
      break;
   case 4:
      state_str = "processing";
      break;
   case 5:
      state_str = "processed";
      break;
   case 6:
      state_str = "to close";
      break;
   case 7:
      state_str = "closing";
      break;
   case 8:
      state_str = "closed";
      break;
   case 9:
      state_str = "done";
      break;
   }
#endif

   /* Connection info */
   if ((state >= 3) && (state < 9)) {
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"connection\" : {%s"
                  "\"remote\" : {%s"
                  "\"protocol\" : \"%s\",%s"
                  "\"addr\" : \"%s\",%s"
                  "\"port\" : %u%s"
                  "},%s"
                  "\"handled_requests\" : %u%s"
                  "},%s",
                  eol,
                  eol,
                  get_proto_name(conn),
                  eol,
                  ri->remote_addr,
                  eol,
                  ri->remote_port,
                  eol,
                  eol,
                  conn->handled_requests,
                  eol,
                  eol);

      connection_info_length += (int)strlen(block);
      if (connection_info_length + reserved_len < buflen) {
         strcat0(buffer, block);
      }
   }

   /* Request info */
   if ((state >= 4) && (state < 6)) {
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"request_info\" : {%s"
                  "\"method\" : \"%s\",%s"
                  "\"uri\" : \"%s\",%s"
                  "\"query\" : %s%s%s%s"
                  "},%s",
                  eol,
                  ri->request_method,
                  eol,
                  ri->request_uri,
                  eol,
                  ri->query_string ? "\"" : "",
                  ri->query_string ? ri->query_string : "null",
                  ri->query_string ? "\"" : "",
                  eol,
                  eol);

      connection_info_length += (int)strlen(block);
      if (connection_info_length + reserved_len < buflen) {
         strcat0(buffer, block);
      }
   }

   /* Execution time information */
   if ((state >= 2) && (state < 9)) {
      char start_time_str[64] = {0};
      char now_str[64] = {0};
      time_t start_time = conn->conn_birth_time;
      time_t now = time(NULL);

      gmt_time_string(start_time_str,
                      sizeof(start_time_str) - 1,
                      &start_time);
      gmt_time_string(now_str, sizeof(now_str) - 1, &now);

      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"time\" : {%s"
                  "\"uptime\" : %.0f,%s"
                  "\"start\" : \"%s\",%s"
                  "\"now\" : \"%s\"%s"
                  "},%s",
                  eol,
                  difftime(now, start_time),
                  eol,
                  start_time_str,
                  eol,
                  now_str,
                  eol,
                  eol);

      connection_info_length += (int)strlen(block);
      if (connection_info_length + reserved_len < buflen) {
         strcat0(buffer, block);
      }
   }

   /* Remote user name */
   if ((ri->remote_user) && (state < 9)) {
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"user\" : {%s"
                  "\"name\" : \"%s\",%s"
                  "},%s",
                  eol,
                  ri->remote_user,
                  eol,
                  eol);

      connection_info_length += (int)strlen(block);
      if (connection_info_length + reserved_len < buflen) {
         strcat0(buffer, block);
      }
   }

   /* Data block */
   if (state >= 3) {
      mg_snprintf(NULL,
                  NULL,
                  block,
                  sizeof(block),
                  "\"data\" : {%s"
                  "\"read\" : %" INT64_FMT ",%s"
                  "\"written\" : %" INT64_FMT "%s"
                  "},%s",
                  eol,
                  conn->consumed_content,
                  eol,
                  conn->num_bytes_sent,
                  eol,
                  eol);

      connection_info_length += (int)strlen(block);
      if (connection_info_length + reserved_len < buflen) {
         strcat0(buffer, block);
      }
   }

   /* State */
   mg_snprintf(NULL,
               NULL,
               block,
               sizeof(block),
               "\"state\" : \"%s\"%s",
               state_str,
               eol);

   connection_info_length += (int)strlen(block);
   if (connection_info_length + reserved_len < buflen) {
      strcat0(buffer, block);
   }

   /* Terminate string */
   if ((buflen > 0) && buffer && buffer[0]) {
      if (connection_info_length < buflen) {
         strcat0(buffer, eoobj);
         strcat0(buffer, eol);
      }
   }
   connection_info_length += reserved_len;

   return connection_info_length;
}
#endif


/* Get system information. It can be printed or stored by the caller.
 * Return the size of available information. */
int
mg_get_system_info(char *buffer, int buflen)
{
   if ((buffer == NULL) || (buflen < 1)) {
      return mg_get_system_info_impl(NULL, 0);
   } else {
      /* Reset buffer, so we can always use strcat. */
      buffer[0] = 0;
      return mg_get_system_info_impl(buffer, buflen);
   }
}


/* Get context information. It can be printed or stored by the caller.
 * Return the size of available information. */
int
mg_get_context_info(const struct mg_context *ctx, char *buffer, int buflen)
{
#if defined(USE_SERVER_STATS)
   if ((buffer == NULL) || (buflen < 1)) {
      return mg_get_context_info_impl(ctx, NULL, 0);
   } else {
      /* Reset buffer, so we can always use strcat. */
      buffer[0] = 0;
      return mg_get_context_info_impl(ctx, buffer, buflen);
   }
#else
   (void)ctx;
   if ((buffer != NULL) && (buflen > 0)) {
      buffer[0] = 0;
   }
   return 0;
#endif
}


#if defined(MG_EXPERIMENTAL_INTERFACES)
int
mg_get_connection_info(const struct mg_context *ctx,
                       int idx,
                       char *buffer,
                       int buflen)
{
   if ((buffer == NULL) || (buflen < 1)) {
      return mg_get_connection_info_impl(ctx, idx, NULL, 0);
   } else {
      /* Reset buffer, so we can always use strcat. */
      buffer[0] = 0;
      return mg_get_connection_info_impl(ctx, idx, buffer, buflen);
   }
}
#endif


/* Initialize this library. This function does not need to be thread safe.
 */
unsigned
mg_init_library(unsigned features)
{
#if !defined(NO_SSL)
   char ebuf[128];
#endif

   unsigned features_to_init = mg_check_feature(features & 0xFFu);
   unsigned features_inited = features_to_init;

   if (mg_init_library_called <= 0) {
      /* Not initialized yet */
      if (0 != pthread_mutex_init(&global_lock_mutex, NULL)) {
         return 0;
      }
   }

   mg_global_lock();

   if (mg_init_library_called <= 0) {
      if (0 != pthread_key_create(&sTlsKey, tls_dtor)) {
         /* Fatal error - abort start. However, this situation should
          * never occur in practice. */
         mg_global_unlock();
         return 0;
      }

#if defined(_WIN32)
      InitializeCriticalSection(&global_log_file_lock);
#endif
#if !defined(_WIN32)
      pthread_mutexattr_init(&pthread_mutex_attr);
      pthread_mutexattr_settype(&pthread_mutex_attr, PTHREAD_MUTEX_RECURSIVE);
#endif

#if defined(USE_LUA)
      lua_init_optional_libraries();
#endif
   }

   mg_global_unlock();

#if !defined(NO_SSL)
   if (features_to_init & MG_FEATURES_SSL) {
      if (!mg_ssl_initialized) {
         if (initialize_ssl(ebuf, sizeof(ebuf))) {
            mg_ssl_initialized = 1;
         } else {
            (void)ebuf;
            DEBUG_TRACE("Initializing SSL failed: %s", ebuf);
            features_inited &= ~((unsigned)(MG_FEATURES_SSL));
         }
      } else {
         /* ssl already initialized */
      }
   }
#endif

   /* Start WinSock for Windows */
   mg_global_lock();
   if (mg_init_library_called <= 0) {
#if defined(_WIN32)
      WSADATA data;
      WSAStartup(MAKEWORD(2, 2), &data);
#endif /* _WIN32 */
      mg_init_library_called = 1;
   } else {
      mg_init_library_called++;
   }
   mg_global_unlock();

   return features_inited;
}


/* Un-initialize this library. */
unsigned
mg_exit_library(void)
{
   if (mg_init_library_called <= 0) {
      return 0;
   }

   mg_global_lock();

   mg_init_library_called--;
   if (mg_init_library_called == 0) {
#if defined(_WIN32)
      (void)WSACleanup();
#endif /* _WIN32  */
#if !defined(NO_SSL)
      if (mg_ssl_initialized) {
         uninitialize_ssl();
         mg_ssl_initialized = 0;
      }
#endif

#if defined(_WIN32)
      (void)DeleteCriticalSection(&global_log_file_lock);
#endif /* _WIN32 */
#if !defined(_WIN32)
      (void)pthread_mutexattr_destroy(&pthread_mutex_attr);
#endif

      (void)pthread_key_delete(sTlsKey);

#if defined(USE_LUA)
      lua_exit_optional_libraries();
#endif

      mg_global_unlock();
      (void)pthread_mutex_destroy(&global_lock_mutex);
      return 1;
   }

   mg_global_unlock();
   return 1;
}


/* End of civetweb.c */