If Drupal 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.

Return value

IP address of client machine, adjusted for reverse proxy.

File

drupal-6.x/includes/bootstrap.inc, line 1317

Functions that need to be loaded on every Drupal request.

Code

function ip_address() {
  static $ip_address = NULL;

  if (!isset($ip_address)) {
    $ip_address = $_SERVER['REMOTE_ADDR'];
    if (variable_get('reverse_proxy', 0) && array_key_exists('HTTP_X_FORWARDED_FOR', $_SERVER)) {
      // If an array of known reverse proxy IPs is provided, then trust
      // the XFF header if request really comes from one of them.
      $reverse_proxy_addresses = variable_get('reverse_proxy_addresses', array());
      if (!empty($reverse_proxy_addresses) && in_array($ip_address, $reverse_proxy_addresses, TRUE)) {
        // If there are several arguments, we need to check the most
        // recently added one, i.e. the last one.
        $ip_address_parts = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
        $ip_address = array_pop($ip_address_parts);
      }
    }
  }

  return $ip_address;
}