mongoose.c

  } 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;
}
#endif // NO_SSL_DL

// Dynamically load SSL library. Set up ctx->ssl_ctx pointer.
static int set_ssl_option(struct mg_context *ctx) {
  int i, size;
  const char *pem;

  // If PEM file is not specified and the init_ssl callback
  // is not specified, skip SSL initialization.
  if ((pem = ctx->config[SSL_CERTIFICATE]) == NULL) {
    //  MG_INIT_SSL
    //  ctx->callbacks.init_ssl == NULL) {
    return 1;
  }

#if !defined(NO_SSL_DL)
  if (!load_dll(ctx, SSL_LIB, ssl_sw) ||
      !load_dll(ctx, CRYPTO_LIB, crypto_sw)) {
    return 0;
  }
#endif // NO_SSL_DL

  // Initialize SSL library
  SSL_library_init();
  SSL_load_error_strings();

  if ((ctx->ssl_ctx = SSL_CTX_new(SSLv23_server_method())) == NULL) {
    cry(fc(ctx), "SSL_CTX_new (server) error: %s", ssl_error());
    return 0;
  }

  // If user callback returned non-NULL, that means that user callback has
  // set up certificate itself. In this case, skip sertificate setting.
  // MG_INIT_SSL
  if (SSL_CTX_use_certificate_file(ctx->ssl_ctx, pem, 1) == 0 ||
      SSL_CTX_use_PrivateKey_file(ctx->ssl_ctx, pem, 1) == 0) {
    cry(fc(ctx), "%s: cannot open %s: %s", __func__, pem, ssl_error());
    return 0;
  }

  if (pem != NULL) {
    (void) SSL_CTX_use_certificate_chain_file(ctx->ssl_ctx, pem);
  }

  // Initialize locking callbacks, needed for thread safety.
  // http://www.openssl.org/support/faq.html#PROG1
  size = sizeof(pthread_mutex_t) * CRYPTO_num_locks();
  if ((ssl_mutexes = (pthread_mutex_t *) malloc((size_t)size)) == NULL) {
    cry(fc(ctx), "%s: cannot allocate mutexes: %s", __func__, ssl_error());
    return 0;
  }

  for (i = 0; i < CRYPTO_num_locks(); i++) {
    pthread_mutex_init(&ssl_mutexes[i], NULL);
  }

  CRYPTO_set_locking_callback(&ssl_locking_callback);
  CRYPTO_set_id_callback(&ssl_id_callback);

  return 1;
}

static void uninitialize_ssl(struct mg_context *ctx) {
  int i;
  if (ctx->ssl_ctx != NULL) {
    CRYPTO_set_locking_callback(NULL);
    for (i = 0; i < CRYPTO_num_locks(); i++) {
      pthread_mutex_destroy(&ssl_mutexes[i]);
    }
    CRYPTO_set_locking_callback(NULL);
    CRYPTO_set_id_callback(NULL);
  }
}
#endif // !NO_SSL

static SOCKET conn2(const char *host, int port, int use_ssl,
                    char *ebuf, size_t ebuf_len) {
  struct sockaddr_in sin;
  struct hostent *he = NULL;
  SOCKET sock = INVALID_SOCKET;

  (void) use_ssl; // Prevent warning for -DNO_SSL case

  if (host == NULL) {
    snprintf(ebuf, ebuf_len, "%s", "NULL host");
#ifndef NO_SSL
  } else if (use_ssl && SSLv23_client_method == NULL) {
    snprintf(ebuf, ebuf_len, "%s", "SSL is not initialized");
    // TODO(lsm): use something threadsafe instead of gethostbyname()
#endif
  } else if ((he = gethostbyname(host)) == NULL) {
    snprintf(ebuf, ebuf_len, "gethostbyname(%s): %s", host, strerror(ERRNO));
  } else if ((sock = socket(PF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) {
    snprintf(ebuf, ebuf_len, "socket(): %s", strerror(ERRNO));
  } else {
    set_close_on_exec(sock);
    sin.sin_family = AF_INET;
    sin.sin_port = htons((uint16_t) port);
    sin.sin_addr = * (struct in_addr *) he->h_addr_list[0];
    if (connect(sock, (struct sockaddr *) &sin, sizeof(sin)) != 0) {
      snprintf(ebuf, ebuf_len, "connect(%s:%d): %s",
               host, port, strerror(ERRNO));
      closesocket(sock);
      sock = INVALID_SOCKET;
    }
  }
  return sock;
}

struct mg_connection *mg_connect(const char *host, int port, int use_ssl,
                                 char *ebuf, size_t ebuf_len) {
  static struct mg_context fake_ctx;
  struct mg_connection *conn = NULL;
  SOCKET sock;

  if ((sock = conn2(host, port, use_ssl, ebuf, ebuf_len)) == INVALID_SOCKET) {
  } else if ((conn = (struct mg_connection *)
              calloc(1, sizeof(*conn) + MAX_REQUEST_SIZE)) == NULL) {
    snprintf(ebuf, ebuf_len, "calloc(): %s", strerror(ERRNO));
    closesocket(sock);
#ifndef NO_SSL
  } else if (use_ssl && (conn->client_ssl_ctx =
                         SSL_CTX_new(SSLv23_client_method())) == NULL) {
    snprintf(ebuf, ebuf_len, "SSL_CTX_new error");
    closesocket(sock);
    free(conn);
    conn = NULL;
#endif // NO_SSL
  } else {
    socklen_t len = sizeof(struct sockaddr);
    conn->buf_size = MAX_REQUEST_SIZE;
    conn->buf = (char *) (conn + 1);
    conn->ctx = &fake_ctx;
    conn->client.sock = sock;
    getsockname(sock, &conn->client.rsa.sa, &len);
    conn->client.is_ssl = use_ssl;
#ifndef NO_SSL
    if (use_ssl) {
      // SSL_CTX_set_verify call is needed to switch off server certificate
      // checking, which is off by default in OpenSSL and on in yaSSL.
      SSL_CTX_set_verify(conn->client_ssl_ctx, 0, 0);
      sslize(conn, conn->client_ssl_ctx, SSL_connect);
    }
#endif
  }

  return conn;
}

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;

  va_start(ap, fmt);
  ebuf[0] = '\0';
  if ((conn = mg_connect(host, port, use_ssl, ebuf, ebuf_len)) == NULL) {
  } else if (mg_vprintf(conn, fmt, ap) <= 0) {
    snprintf(ebuf, ebuf_len, "%s", "Error sending request");
  } else {
    getreq(conn, ebuf, ebuf_len);
  }
  if (ebuf[0] != '\0' && conn != NULL) {
    mg_close_connection(conn);
    conn = NULL;
  }

  return conn;
}

static const struct {
  const char *extension;
  size_t ext_len;
  const char *mime_type;
} builtin_mime_types[] = {
  {".html", 5, "text/html"},
  {".htm", 4, "text/html"},
  {".shtm", 5, "text/html"},
  {".shtml", 6, "text/html"},
  {".css", 4, "text/css"},
  {".js",  3, "application/x-javascript"},
  {".ico", 4, "image/x-icon"},
  {".gif", 4, "image/gif"},
  {".jpg", 4, "image/jpeg"},
  {".jpeg", 5, "image/jpeg"},
  {".png", 4, "image/png"},
  {".svg", 4, "image/svg+xml"},
  {".txt", 4, "text/plain"},
  {".torrent", 8, "application/x-bittorrent"},
  {".wav", 4, "audio/x-wav"},
  {".mp3", 4, "audio/x-mp3"},
  {".mid", 4, "audio/mid"},
  {".m3u", 4, "audio/x-mpegurl"},
  {".ogg", 4, "application/ogg"},
  {".ram", 4, "audio/x-pn-realaudio"},
  {".xml", 4, "text/xml"},
  {".json",  5, "text/json"},
  {".xslt", 5, "application/xml"},
  {".xsl", 4, "application/xml"},
  {".ra",  3, "audio/x-pn-realaudio"},
  {".doc", 4, "application/msword"},
  {".exe", 4, "application/octet-stream"},
  {".zip", 4, "application/x-zip-compressed"},
  {".xls", 4, "application/excel"},
  {".tgz", 4, "application/x-tar-gz"},
  {".tar", 4, "application/x-tar"},
  {".gz",  3, "application/x-gunzip"},
  {".arj", 4, "application/x-arj-compressed"},
  {".rar", 4, "application/x-arj-compressed"},
  {".rtf", 4, "application/rtf"},
  {".pdf", 4, "application/pdf"},
  {".swf", 4, "application/x-shockwave-flash"},
  {".mpg", 4, "video/mpeg"},
  {".webm", 5, "video/webm"},
  {".mpeg", 5, "video/mpeg"},
  {".mov", 4, "video/quicktime"},
  {".mp4", 4, "video/mp4"},
  {".m4v", 4, "video/x-m4v"},
  {".asf", 4, "video/x-ms-asf"},
  {".avi", 4, "video/x-msvideo"},
  {".bmp", 4, "image/bmp"},
  {".ttf", 4, "application/x-font-ttf"},
  {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_context *ctx, const char *path,
                          struct vec *vec) {
  struct vec ext_vec, mime_vec;
  const char *list, *ext;
  size_t path_len;

  path_len = strlen(path);

  // Scan user-defined mime types first, in case user wants to
  // override default mime types.
  list = 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);
}

static void print_dir_entry(const struct de *de) {
  char size[64], mod[64], href[PATH_MAX * 3];
  const char *slash = de->file.is_directory ? "/" : "";

  if (de->file.is_directory) {
    mg_snprintf(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(size, sizeof(size), "%d", (int) de->file.size);
    } else if (de->file.size < 0x100000) {
      mg_snprintf(size, sizeof(size),
                  "%.1fk", (double) de->file.size / 1024.0);
    } else if (de->file.size < 0x40000000) {
      mg_snprintf(size, sizeof(size),
                  "%.1fM", (double) de->file.size / 1048576);
    } else {
      mg_snprintf(size, sizeof(size),
                  "%.1fG", (double) de->file.size / 1073741824);
    }
  }
  strftime(mod, sizeof(mod), "%d-%b-%Y %H:%M",
           localtime(&de->file.modification_time));
  mg_url_encode(de->file_name, href, sizeof(href));
  de->conn->num_bytes_sent += mg_chunked_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.uri, href, slash, de->file_name, slash, mod, size);
}

// 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) {
  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.modification_time == b->file.modification_time ? 0 :
      a->file.modification_time > b->file.modification_time ? 1 : -1;
  }

  return query_string[1] == 'd' ? -cmp_result : cmp_result;
}

static int must_hide_file(struct mg_connection *conn, const char *path) {
  const char *pw_pattern = "**" PASSWORDS_FILE_NAME "$";
  const char *pattern = conn->ctx->config[HIDE_FILES];
  return match_prefix(pw_pattern, strlen(pw_pattern), path) > 0 ||
    (pattern != NULL && match_prefix(pattern, strlen(pattern), path) > 0);
}

static int scan_directory(struct mg_connection *conn, const char *dir,
                          void *data, void (*cb)(struct de *, void *)) {
  char path[PATH_MAX];
  struct dirent *dp;
  DIR *dirp;
  struct de de;

  if ((dirp = opendir(dir)) == NULL) {
    return 0;
  } else {
    de.conn = conn;

    while ((dp = 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(path, sizeof(path), "%s%c%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));
      mg_stat(path, &de.file);

      de.file_name = dp->d_name;
      cb(&de, data);
    }
    (void) closedir(dirp);
  }
  return 1;
}

static int remove_directory(struct mg_connection *conn, const char *dir) {
  char path[PATH_MAX];
  struct dirent *dp;
  DIR *dirp;
  struct de de;

  if ((dirp = opendir(dir)) == NULL) {
    return 0;
  } else {
    de.conn = conn;

    while ((dp = readdir(dirp)) != NULL) {
      // Do not show current dir, but show hidden files
      if (!strcmp(dp->d_name, ".") ||
          !strcmp(dp->d_name, "..")) {
        continue;
      }

      mg_snprintf(path, sizeof(path), "%s%c%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));
      mg_stat(path, &de.file);
      if(de.file.modification_time) {
          if(de.file.is_directory) {
              remove_directory(conn, path);
          } else {
              mg_remove(path);
          }
      }

    }
    (void) closedir(dirp);

    rmdir(dir);
  }

  return 1;
}

struct dir_scan_data {
  struct de *entries;
  int num_entries;
  int arr_size;
};

// Behaves like realloc(), but frees original pointer on failure
static void *realloc2(void *ptr, size_t size) {
  void *new_ptr = realloc(ptr, size);
  if (new_ptr == NULL) {
    free(ptr);
  }
  return new_ptr;
}

static void 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): 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++;
  }
}

static void handle_directory_request(struct mg_connection *conn,
                                     const char *dir) {
  int i, sort_direction;
  struct dir_scan_data data = { NULL, 0, 128 };

  if (!scan_directory(conn, dir, &data, dir_scan_callback)) {
    send_http_error(conn, 500, "Cannot open directory",
                    "Error: opendir(%s): %s", dir, strerror(ERRNO));
    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, "%s",
            "HTTP/1.1 200 OK\r\n"
            "Transfer-Encoding: Chunked\r\n"
            "Content-Type: text/html; charset=utf-8\r\n\r\n");

  conn->num_bytes_sent += mg_chunked_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.uri, conn->request_info.uri,
      sort_direction, sort_direction, sort_direction);

  // Print first entry - link to a parent directory
  conn->num_bytes_sent += mg_chunked_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.uri, "..", "Parent directory", "-", "-");

  // Sort and print directory entries
  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]);
    free(data.entries[i].file_name);
  }
  free(data.entries);

  conn->num_bytes_sent += mg_chunked_printf(conn, "%s",
                                            "</table></body></html>");
  conn->num_bytes_sent += mg_write(conn, "0\r\n\r\n", 5);
  conn->status_code = 200;
}


// Return number of bytes left to read for this connection
static int64_t left_to_read(const struct mg_connection *conn) {
  return conn->content_len + conn->request_len - conn->num_bytes_read;
}

static int call_user(int type, struct mg_connection *conn, void *p) {
  if (conn != NULL && conn->ctx != NULL) {
    conn->event.user_data = conn->ctx->user_data;
    conn->event.type = type;
    conn->event.event_param = p;
    conn->event.request_info = &conn->request_info;
    conn->event.conn = conn;
  }
  return conn == NULL || conn->ctx == NULL || conn->ctx->event_handler == NULL ?
    0 : conn->ctx->event_handler(&conn->event);
}

static FILE *mg_fopen(const char *path, const char *mode) {
#ifdef _WIN32
  wchar_t wbuf[PATH_MAX], wmode[20];
  to_unicode(path, wbuf, ARRAY_SIZE(wbuf));
  MultiByteToWideChar(CP_UTF8, 0, mode, -1, wmode, ARRAY_SIZE(wmode));
  return _wfopen(wbuf, wmode);
#else
  return fopen(path, mode);
#endif
}

static void sockaddr_to_string(char *buf, size_t len,
                                     const union usa *usa) {
  buf[0] = '\0';
#if defined(USE_IPV6)
  inet_ntop(usa->sa.sa_family, usa->sa.sa_family == AF_INET ?
            (void *) &usa->sin.sin_addr :
            (void *) &usa->sin6.sin6_addr, buf, len);
#elif defined(_WIN32)
  // Only Windoze Vista (and newer) have inet_ntop()
  strncpy(buf, inet_ntoa(usa->sin.sin_addr), len);
#else
  inet_ntop(usa->sa.sa_family, (void *) &usa->sin.sin_addr, buf, len);
#endif
}

// Print error message to the opened error log stream.
static void cry(struct mg_connection *conn, const char *fmt, ...) {
  char buf[MG_BUF_LEN], src_addr[IP_ADDR_STR_LEN];
  va_list ap;
  FILE *fp;
  time_t timestamp;

  va_start(ap, fmt);
  (void) vsnprintf(buf, sizeof(buf), fmt, ap);
  va_end(ap);

  // 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 (call_user(MG_EVENT_LOG, conn, buf) == 0) {
    fp = conn->ctx == NULL || conn->ctx->config[ERROR_LOG_FILE] == NULL ? NULL :
      fopen(conn->ctx->config[ERROR_LOG_FILE], "a+");

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

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

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

      fprintf(fp, "%s", buf);
      fputc('\n', fp);
      funlockfile(fp);
      fclose(fp);
    }
  }
}

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

// 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 = conn->request_info.http_version;
  const char *header = mg_get_header(conn, "Connection");
  if (conn->must_close ||
      conn->status_code == 401 ||
      mg_strcasecmp(conn->ctx->config[ENABLE_KEEP_ALIVE], "yes") != 0 ||
      (header != NULL && mg_strcasecmp(header, "keep-alive") != 0) ||
      (header == NULL && http_version && strcmp(http_version, "1.1"))) {
    return 0;
  }
  return 1;
}

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

static void send_http_error(struct mg_connection *conn, int status,
                            const char *reason, const char *fmt, ...) {
  char buf[MG_BUF_LEN];
  va_list ap;
  int len = 0;

  conn->status_code = status;
  buf[0] = '\0';

  // Errors 1xx, 204 and 304 MUST NOT send a body
  if (status > 199 && status != 204 && status != 304) {
    len = mg_snprintf(buf, sizeof(buf), "Error %d: %s", status, reason);
    buf[len++] = '\n';

    va_start(ap, fmt);
    len += mg_vsnprintf(buf + len, sizeof(buf) - len, fmt, ap);
    va_end(ap);
  }
  DEBUG_TRACE(("[%s]", buf));

  if (call_user(MG_HTTP_ERROR, conn, (void *) (long) status) == 0) {
    mg_printf(conn, "HTTP/1.1 %d %s\r\n"
              "Content-Length: %d\r\n"
              "Connection: %s\r\n\r\n", status, reason, len,
              suggest_connection_header(conn));
    conn->num_bytes_sent += mg_printf(conn, "%s", buf);
  }
}

// Write data to the IO channel - opened file descriptor, socket or SSL
// descriptor. Return number of bytes written.
static int64_t push(FILE *fp, SOCKET sock, SSL *ssl, const char *buf,
                    int64_t len) {
  int64_t sent;
  int n, k;

  (void) ssl;  // Get rid of warning
  sent = 0;
  while (sent < len) {

    // How many bytes we send in this iteration
    k = len - sent > INT_MAX ? INT_MAX : (int) (len - sent);

#if !defined(NO_SSL)
    if (ssl != NULL) {
      n = SSL_write(ssl, buf + sent, k);
    } else
#endif
    if (fp != NULL) {
      n = (int) fwrite(buf + sent, 1, (size_t) k, fp);
      if (ferror(fp))
        n = -1;
    } else {
      n = send(sock, buf + sent, (size_t) k, MSG_NOSIGNAL);
    }

    if (n <= 0)
      break;

    sent += n;
  }

  return sent;
}

// Read from IO channel - opened file descriptor, socket, or SSL descriptor.
// Return negative value on error, or number of bytes read on success.
static int pull(FILE *fp, struct mg_connection *conn, char *buf, int len) {
  int nread;

  if (len <= 0) return 0;
  if (fp != NULL) {
    // 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 = read(fileno(fp), buf, (size_t) len);
#ifndef NO_SSL
  } else if (conn->ssl != NULL) {
    nread = SSL_read(conn->ssl, buf, len);
#endif
  } else {
    nread = recv(conn->client.sock, buf, (size_t) len, 0);
  }
  if (nread > 0) {
    conn->num_bytes_read += nread;
  }

  return conn->ctx->stop_flag ? -1 : nread;
}

static int pull_all(FILE *fp, struct mg_connection *conn, char *buf, int len) {
  int n, nread = 0;

  while (len > 0 && conn->ctx->stop_flag == 0) {
    n = pull(fp, conn, buf + nread, len);
    if (n < 0) {
      nread = n;  // Propagate the error
      break;
    } else if (n == 0) {
      break;  // No more data to read
    } else {
      nread += n;
      len -= n;
    }
  }

  return nread;
}

int mg_read(struct mg_connection *conn, void *buf, int len) {
  int n, buffered_len, nread = 0;
  int64_t left;

  if (conn->content_len <= 0) {
    return 0;
  }

  // conn->buf           body
  //    |=================|==========|===============|
  //    |<--request_len-->|                          |
  //    |<-----------data_len------->|      conn->buf + conn->buf_size

  // First, check for data buffered in conn->buf by read_request().
  if (len > 0 && (buffered_len = conn->data_len - conn->request_len) > 0) {
    char *body = conn->buf + conn->request_len;
    if (buffered_len > len) buffered_len = len;
    if (buffered_len > conn->content_len) buffered_len = (int)conn->content_len;

    memcpy(buf, body, (size_t) buffered_len);
    memmove(body, body + buffered_len,
            &conn->buf[conn->data_len] - &body[buffered_len]);
    len -= buffered_len;
    conn->data_len -= buffered_len;
    nread += buffered_len;
  }

  // Read data from the socket.
  if (len > 0 && (left = left_to_read(conn)) > 0) {
    if (left < len) {
      len = (int) left;
    }
    n = pull_all(NULL, conn, (char *) buf + nread, (int) len);
    nread = n >= 0 ? nread + n : n;
  }

  return nread;
}

int mg_write(struct mg_connection *conn, const void *buf, int len) {
  return push(NULL, conn->client.sock, conn->ssl, (const char *) buf,
                 (int64_t) len);
}

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 (src[i] == '%' && i < src_len - 2 &&
        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) {
  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)) {

        // 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;
        }
        assert(s >= p);

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

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

  return len;
}

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) {
    len = -2;
  } else if (var_name == NULL || (s = cookie_header) == NULL) {
    len = -1;
    dst[0] = '\0';
  } else {
    name_len = (int) strlen(var_name);
    end = s + strlen(s);
    dst[0] = '\0';

    for (; (s = mg_strcasestr(s, var_name)) != NULL; s += name_len) {
      if (s[name_len] == '=') {
        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 = p - s;
          mg_strlcpy(dst, s, (size_t) len + 1);
        } else {
          len = -3;
        }
        break;
      }
    }
  }
  return len;
}

// Return 1 if real file has been found, 0 otherwise
static int convert_uri_to_file_name(struct mg_connection *conn, char *buf,
                                    size_t buf_len, struct file *filep) {
  struct vec a, b;
  const char *rewrite, *uri = conn->request_info.uri,
        *root = conn->ctx->config[DOCUMENT_ROOT];
  char *p;
  int match_len;
  char gz_path[PATH_MAX];
  char const* accept_encoding;

  // No filesystem access
  if (root == NULL) {
    return 0;
  }

  // Using buf_len - 1 because memmove() for PATH_INFO may shift part
  // of the path one byte on the right.
  // If document_root is NULL, leave the file empty.
  mg_snprintf(buf, buf_len - 1, "%s%s", root, uri);

  rewrite = conn->ctx->config[REWRITE];
  while ((rewrite = next_option(rewrite, &a, &b)) != NULL) {
    if ((match_len = match_prefix(a.ptr, a.len, uri)) > 0) {
      mg_snprintf(buf, buf_len - 1, "%.*s%s", (int) b.len, b.ptr,
                  uri + match_len);
      break;
    }
  }

  if (mg_stat(buf, filep)) {
    return 1;
  }

  // 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 ((accept_encoding = mg_get_header(conn, "Accept-Encoding")) != NULL) {
    if (strstr(accept_encoding,"gzip") != NULL) {
      snprintf(gz_path, sizeof(gz_path), "%s.gz", buf);
      if (mg_stat(gz_path, filep)) {
        filep->gzipped = 1;
        return 1;
      }
    }
  }

  // Support PATH_INFO for CGI scripts.
  for (p = buf + strlen(root == NULL ? "" : root); *p != '\0'; p++) {
    if (*p == '/') {
      *p = '\0';
      if (match_prefix(conn->ctx->config[CGI_EXTENSIONS],
                       strlen(conn->ctx->config[CGI_EXTENSIONS]), buf) > 0 &&
          mg_stat(buf, filep)) {
        // Shift PATH_INFO block one character right, e.g.
        //  "/x.cgi/foo/bar\x00" => "/x.cgi\x00/foo/bar\x00"
        // conn->path_info is pointing to the local variable "path" declared
        // in handle_request(), so PATH_INFO is not valid after
        // handle_request returns.
        conn->path_info = p + 1;
        memmove(p + 2, p + 1, strlen(p + 1) + 1);  // +1 is for trailing \0
        p[1] = '/';
        return 1;
      } else {
        *p = '/';
      }
    }
  }

  return 0;
}

// Check whether full request is buffered. Return:
//   -1  if request is malformed
//    0  if request is not yet fully buffered
//   >0  actual request length, including last \r\n\r\n
static int get_request_len(const char *buf, int buf_len) {
  int i;

  for (i = 0; i < buf_len; i++) {
    // Control characters are not allowed but >=128 is.