1 bootstrap.inc ip_address()

Returns the IP address of the client machine.

If Backdrop is behind a reverse proxy, we use the X-Forwarded-For header instead of $_SERVER['REMOTE_ADDR'], which would be the IP address of the proxy server, and not the client's. The actual header name can be configured by the reverse_proxy_header variable.

Return value

IP address of client machine, adjusted for reverse proxy and/or cluster: environments.


core/includes/bootstrap.inc, line 3868
Functions that need to be loaded on every Backdrop request.


function ip_address() {
  $ip_address = &backdrop_static(__FUNCTION__);

  if (!isset($ip_address)) {
    $ip_address = $_SERVER['REMOTE_ADDR'];

    if (settings_get('reverse_proxy', 0)) {
      $reverse_proxy_header = settings_get('reverse_proxy_header', 'HTTP_X_FORWARDED_FOR');
      if (!empty($_SERVER[$reverse_proxy_header])) {
        // If an array of known reverse proxy IPs is provided, then trust
        // the XFF header if request really comes from one of them.
        $reverse_proxy_addresses = settings_get('reverse_proxy_addresses', array());

        // Turn XFF header into an array.
        $forwarded = explode(',', $_SERVER[$reverse_proxy_header]);

        // Trim the forwarded IPs; they may have been delimited by commas and spaces.
        $forwarded = array_map('trim', $forwarded);

        // Tack direct client IP onto end of forwarded array.
        $forwarded[] = $ip_address;

        // Eliminate all trusted IPs.
        $untrusted = array_diff($forwarded, $reverse_proxy_addresses);

        if (!empty($untrusted)) {
          // The right-most IP is the most specific we can trust.
          $ip_address = array_pop($untrusted);
        else {
          // All IP addresses in the forwarded array are configured proxy IPs
          // (and thus trusted). We take the leftmost IP.
          $ip_address = array_shift($forwarded);

  return $ip_address;