mongoose.c

  count = (ctx->bits[0] >> 3) & 0x3F;

  p = ctx->in + count;
  *p++ = 0x80;
  count = 64 - 1 - count;
  if (count < 8) {
    memset(p, 0, count);
    byteReverse(ctx->in, 16);
    MD5Transform(ctx->buf, (uint32_t *) ctx->in);
    memset(ctx->in, 0, 56);
  } else {
    memset(p, 0, count - 8);
  }
  byteReverse(ctx->in, 14);

  a = (uint32_t *)ctx->in;
  a[14] = ctx->bits[0];
  a[15] = ctx->bits[1];

  MD5Transform(ctx->buf, (uint32_t *) ctx->in);
  byteReverse((unsigned char *) ctx->buf, 4);
  memcpy(digest, ctx->buf, 16);
  memset((char *) ctx, 0, sizeof(*ctx));
}
#endif // !HAVE_MD5



// 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], ...) {
  unsigned char hash[16];
  const char *p;
  va_list ap;
  MD5_CTX ctx;

  MD5Init(&ctx);

  va_start(ap, buf);
  while ((p = va_arg(ap, const char *)) != NULL) {
    MD5Update(&ctx, (const unsigned char *) p, (unsigned) strlen(p));
  }
  va_end(ap);

  MD5Final(hash, &ctx);
  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
  // TODO(lsm): check for authentication timeout
  if (// strcmp(dig->uri, c->ouri) != 0 ||
      strlen(response) != 32
      // || now - strtoul(dig->nonce, NULL, 10) > 3600
      ) {
    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 FILE *open_auth_file(struct mg_connection *conn, const char *path) {
  char name[PATH_MAX];
  const char *p, *e, *gpass = conn->ctx->config[GLOBAL_PASSWORDS_FILE];
  struct file file = STRUCT_FILE_INITIALIZER;
  FILE *fp = NULL;

  if (gpass != NULL) {
    // Use global passwords file
    fp = mg_fopen(gpass, "r");
    // Important: using local struct file to test path for is_directory flag.
    // If filep is used, mg_stat() makes it appear as if auth file was opened.
  } else if (mg_stat(path, &file) && file.is_directory) {
    mg_snprintf(name, sizeof(name), "%s%c%s",
                path, '/', PASSWORDS_FILE_NAME);
    fp = mg_fopen(name, "r");
  } 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(name, sizeof(name), "%.*s%c%s",
                (int) (e - p), p, '/', PASSWORDS_FILE_NAME);
    fp = mg_fopen(name, "r");
  }

  return fp;
}

// 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;

  (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;
    }
  }

  // CGI needs it as REMOTE_USER
  if (ah->user != NULL) {
    conn->request_info.remote_user = mg_strdup(ah->user);
  } else {
    return 0;
  }

  return 1;
}

// Authorize against the opened passwords file. Return 1 if authorized.
static int authorize(struct mg_connection *conn, FILE *fp) {
  struct ah ah;
  char line[256], f_user[256], ha1[256], f_domain[256], buf[MG_BUF_LEN];

  if (!parse_auth_header(conn, buf, sizeof(buf), &ah)) {
    return 0;
  }

  // Loop over passwords file
  while (fgets(line, sizeof(line), fp) != NULL) {
    if (sscanf(line, "%[^:]:%[^:]:%s", f_user, f_domain, ha1) != 3) {
      continue;
    }

    if (!strcmp(ah.user, f_user) &&
        !strcmp(conn->ctx->config[AUTHENTICATION_DOMAIN], f_domain))
      return check_password(conn->request_info.request_method, ha1, ah.uri,
                            ah.nonce, ah.nc, ah.cnonce, ah.qop, ah.response);
  }

  return 0;
}

// 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;
  FILE *fp = NULL;
  int authorized = 1;

  list = conn->ctx->config[PROTECT_URI];
  while ((list = next_option(list, &uri_vec, &filename_vec)) != NULL) {
    if (!memcmp(conn->request_info.uri, uri_vec.ptr, uri_vec.len)) {
      mg_snprintf(fname, sizeof(fname), "%.*s",
                  (int) filename_vec.len, filename_vec.ptr);
      fp = mg_fopen(fname, "r");
      break;
    }
  }

  if (fp == NULL) {
    fp = open_auth_file(conn, path);
  }

  if (fp != NULL) {
    authorized = authorize(conn, fp);
    fclose(fp);
  }

  return authorized;
}

static void send_authorization_request(struct mg_connection *conn) {
  conn->status_code = 401;
  mg_printf(conn,
            "HTTP/1.1 401 Unauthorized\r\n"
            "Content-Length: 0\r\n"
            "WWW-Authenticate: Digest qop=\"auth\", "
            "realm=\"%s\", nonce=\"%lu\"\r\n\r\n",
            conn->ctx->config[AUTHENTICATION_DOMAIN],
            (unsigned long) time(NULL));
}

static int is_authorized_for_put(struct mg_connection *conn) {
  const char *passfile = conn->ctx->config[PUT_DELETE_PASSWORDS_FILE];
  FILE *fp;
  int ret = 0;

  if (passfile != NULL && (fp = mg_fopen(passfile, "r")) != NULL) {
    ret = authorize(conn, fp);
    fclose(fp);
  }

  return ret;
}

int mg_modify_passwords_file(const char *fname, const char *domain,
                             const char *user, const char *pass) {
  int found;
  char line[512], u[512], d[512], ha1[33], tmp[PATH_MAX];
  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;
  }

  (void) snprintf(tmp, sizeof(tmp), "%s.tmp", fname);

  // Create the file if does not exist
  if ((fp = fopen(fname, "a+")) != NULL) {
    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, "%[^:]:%[^:]:%*s", u, d) != 2) {
      continue;
    }

    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
  remove(fname);
  rename(tmp, fname);

  return 1;
}

#if defined(_WIN32)
static pthread_t pthread_self(void) {
  return GetCurrentThreadId();
}

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

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

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

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

static int pthread_cond_init(pthread_cond_t *cv, const void *unused) {
  (void) unused;
  cv->signal = CreateEvent(NULL, FALSE, FALSE, NULL);
  cv->broadcast = CreateEvent(NULL, TRUE, FALSE, NULL);
  return cv->signal != NULL && cv->broadcast != NULL ? 0 : -1;
}

static int pthread_cond_wait(pthread_cond_t *cv, pthread_mutex_t *mutex) {
  HANDLE handles[] = {cv->signal, cv->broadcast};
  ReleaseMutex(*mutex);
  WaitForMultipleObjects(2, handles, FALSE, INFINITE);
  return WaitForSingleObject(*mutex, INFINITE) == WAIT_OBJECT_0? 0 : -1;
}

static int pthread_cond_signal(pthread_cond_t *cv) {
  return SetEvent(cv->signal) == 0 ? -1 : 0;
}

static int pthread_cond_broadcast(pthread_cond_t *cv) {
  // Implementation with PulseEvent() has race condition, see
  // http://www.cs.wustl.edu/~schmidt/win32-cv-1.html
  return PulseEvent(cv->broadcast) == 0 ? -1 : 0;
}

static int pthread_cond_destroy(pthread_cond_t *cv) {
  return CloseHandle(cv->signal) && CloseHandle(cv->broadcast) ? 0 : -1;
}

// 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] = '\\';
    // i > 0 check is 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));
  }
}

// Encode 'path' which is assumed UTF-8 string, into UNICODE string.
// wbuf and wbuf_len is a target buffer and its length.
static void to_unicode(const char *path, wchar_t *wbuf, size_t wbuf_len) {
  char buf[PATH_MAX * 2], buf2[PATH_MAX * 2];

  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';
  }
}

#if defined(_WIN32_WCE)
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;
}

static struct tm *localtime(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;
}

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

static size_t strftime(char *dst, size_t dst_size, const char *fmt,
                       const struct tm *tm) {
  (void) snprintf(dst, dst_size, "implement strftime() for WinCE");
  return 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 char *path, struct file *filep) {
  wchar_t wbuf[PATH_MAX] = L"\\\\?\\";
  WIN32_FILE_ATTRIBUTE_DATA info;

  filep->modification_time = 0;
  to_unicode(path, wbuf + 4, ARRAY_SIZE(wbuf) - 4);
  if (GetFileAttributesExW(wbuf, GetFileExInfoStandard, &info) != 0) {
    filep->size = MAKEUQUAD(info.nFileSizeLow, info.nFileSizeHigh);
    filep->modification_time = SYS2UNIX_TIME(
        info.ftLastWriteTime.dwLowDateTime,
        info.ftLastWriteTime.dwHighDateTime);
    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 filep->modification_time != 0;
}

static int mg_remove(const char *path) {
  wchar_t wbuf[PATH_MAX];
  to_unicode(path, wbuf, ARRAY_SIZE(wbuf));
  return DeleteFileW(wbuf) ? 0 : -1;
}

static int mg_mkdir(const char *path, int mode) {
  char buf[PATH_MAX];
  wchar_t wbuf[PATH_MAX];

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

  (void) MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, ARRAY_SIZE(wbuf));

  return CreateDirectoryW(wbuf, NULL) ? 0 : -1;
}

// Implementation of POSIX opendir/closedir/readdir for Windows.
static DIR * opendir(const char *name) {
  DIR *dir = NULL;
  wchar_t wpath[PATH_MAX];
  DWORD attrs;

  if (name == NULL) {
    SetLastError(ERROR_BAD_ARGUMENTS);
  } else if ((dir = (DIR *) malloc(sizeof(*dir))) == NULL) {
    SetLastError(ERROR_NOT_ENOUGH_MEMORY);
  } else {
    to_unicode(name, wpath, ARRAY_SIZE(wpath));
    attrs = GetFileAttributesW(wpath);
    if (attrs != 0xFFFFFFFF &&
        ((attrs & FILE_ATTRIBUTE_DIRECTORY) == FILE_ATTRIBUTE_DIRECTORY)) {
      (void) wcscat(wpath, L"\\*");
      dir->handle = FindFirstFileW(wpath, &dir->info);
      dir->result.d_name[0] = '\0';
    } else {
      free(dir);
      dir = NULL;
    }
  }

  return dir;
}

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

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

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

  return result;
}

static struct dirent *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;
}

#ifndef HAVE_POLL
static int poll(struct pollfd *pfd, int n, int milliseconds) {
  struct timeval tv;
  fd_set set;
  int i, result;
  SOCKET maxfd = 0;

  tv.tv_sec = milliseconds / 1000;
  tv.tv_usec = (milliseconds % 1000) * 1000;
  FD_ZERO(&set);

  for (i = 0; i < n; i++) {
    FD_SET((SOCKET) pfd[i].fd, &set);
    pfd[i].revents = 0;

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

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

  return result;
}
#endif // HAVE_POLL

static void set_close_on_exec(SOCKET sock) {
  (void) SetHandleInformation((HANDLE) sock, HANDLE_FLAG_INHERIT, 0);
}

int mg_start_thread(mg_thread_func_t f, void *p) {
  return (long)_beginthread((void (__cdecl *)(void *)) f, 0, p) == -1L ? -1 : 0;
}

static HANDLE dlopen(const char *dll_name, int flags) {
  wchar_t wbuf[PATH_MAX];
  (void) flags;
  to_unicode(dll_name, wbuf, ARRAY_SIZE(wbuf));
  return LoadLibraryW(wbuf);
}

#if !defined(NO_CGI)
#define SIGKILL 0
static int kill(pid_t pid, int sig_num) {
  (void) TerminateProcess(pid, sig_num);
  (void) CloseHandle(pid);
  return 0;
}

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,
                           int fdout, const char *dir) {
  HANDLE me;
  char *interp, full_interp[PATH_MAX], full_dir[PATH_MAX],
       cmdline[PATH_MAX], buf[PATH_MAX];
  FILE *fp;
  STARTUPINFOA si;
  PROCESS_INFORMATION pi = { 0 };

  (void) envp;

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

  // TODO(lsm): redirect CGI errors to the error log file
  si.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
  si.wShowWindow = SW_HIDE;

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

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

    // Read the first line of the script into the buffer
    snprintf(cmdline, sizeof(cmdline), "%s%c%s", dir, '/', prog);
    if ((fp = mg_fopen(cmdline, "r")) != NULL) {
      fgets(buf, sizeof(buf), fp);
      fclose(fp);
      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);

  mg_snprintf(cmdline, sizeof(cmdline), "%s%s\"%s\\%s\"",
              interp, interp[0] == '\0' ? "" : " ", full_dir, prog);

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

  (void) CloseHandle(si.hStdOutput);
  (void) CloseHandle(si.hStdInput);
  (void) CloseHandle(pi.hThread);

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

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

#if !defined(_WIN32)
static int mg_stat(const char *path, struct file *filep) {
  struct stat st;

  filep->modification_time = (time_t) 0;
  if (stat(path, &st) == 0) {
    filep->size = st.st_size;
    filep->modification_time = st.st_mtime;
    filep->is_directory = S_ISDIR(st.st_mode);

    // See https://github.com/cesanta/mongoose/issues/109
    // Some filesystems report modification time as 0. Artificially
    // bump it up to mark mg_stat() success.
    if (filep->modification_time == (time_t) 0) {
      filep->modification_time = (time_t) 1;
    }
  }

  return filep->modification_time != (time_t) 0;
}

static void set_close_on_exec(int fd) {
  fcntl(fd, F_SETFD, FD_CLOEXEC);
}

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 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

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

  return result;
}

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

  (void) envblk;

  if ((pid = fork()) == -1) {
    // Parent
    send_http_error(conn, 500, http_500_error, "fork(): %s", strerror(ERRNO));
  } else if (pid == 0) {
    // Child
    if (chdir(dir) != 0) {
      cry(conn, "%s: chdir(%s): %s", __func__, dir, strerror(ERRNO));
    } else if (dup2(fdin, 0) == -1) {
      cry(conn, "%s: dup2(%d, 0): %s", __func__, fdin, strerror(ERRNO));
    } else if (dup2(fdout, 1) == -1) {
      cry(conn, "%s: dup2(%d, 1): %s", __func__, fdout, strerror(ERRNO));
    } else {
      // Not redirecting stderr to stdout, to avoid output being littered
      // with the error messages.
      (void) close(fdin);
      (void) close(fdout);

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

  flags = fcntl(sock, F_GETFL, 0);
  (void) fcntl(sock, F_SETFL, flags | O_NONBLOCK);

  return 0;
}
#endif // _WIN32


// 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 **buf, size_t 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(NULL, 0, fmt, ap_copy);

  if (len > (int) size &&
      (size = len + 1) > 0 &&
      (*buf = (char *) malloc(size)) == NULL) {
    len = -1;  // Allocation failed, mark failure
  } else {
    va_copy(ap_copy, ap);
    vsnprintf(*buf, size, fmt, ap_copy);
  }

  return len;
}

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

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

  return len;
}

int mg_printf(struct mg_connection *conn, const char *fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  return mg_vprintf(conn, fmt, ap);
}

static int mg_chunked_printf(struct mg_connection *conn, const char *fmt, ...) {
  char mem[MG_BUF_LEN], *buf = mem;
  int len;

  va_list ap;
  va_start(ap, fmt);
  if ((len = alloc_vprintf(&buf, sizeof(mem), fmt, ap)) > 0) {
    len = mg_printf(conn, "%X\r\n%s\r\n", len, buf);
  }

  if (buf != mem && buf != NULL) {
    free(buf);
  }

  return len;
}



#if !defined(NO_SSL)
// set_ssl_option() 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},
  {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},
  {NULL,    NULL}
};

static pthread_mutex_t *ssl_mutexes;

static int sslize(struct mg_connection *conn, SSL_CTX *s, int (*func)(SSL *)) {
  return (conn->ssl = SSL_new(s)) != NULL &&
    SSL_set_fd(conn->ssl, conn->client.sock) == 1 &&
    func(conn->ssl) == 1;
}

// Return OpenSSL error message
static const char *ssl_error(void) {
  unsigned long err;
  err = ERR_get_error();
  return err == 0 ? "" : ERR_error_string(err, NULL);
}

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]);
  }
}

static unsigned long ssl_id_callback(void) {
  return (unsigned long) pthread_self();
}

#if !defined(NO_SSL_DL)
static int load_dll(struct mg_context *ctx, const char *dll_name,
                    struct ssl_func *sw) {
  union {void *p; void (*fp)(void);} u;
  void  *dll_handle;
  struct ssl_func *fp;

  if ((dll_handle = dlopen(dll_name, RTLD_LAZY)) == NULL) {
    cry(fc(ctx), "%s: cannot load %s", __func__, dll_name);
    return 0;
  }

  for (fp = sw; fp->name != NULL; fp++) {
#ifdef _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) {
      cry(fc(ctx), "%s: %s: cannot find %s", __func__, dll_name, fp->name);
      return 0;
    } else {
      fp->ptr = u.fp;
    }
  }

  return 1;