File

includes/misc.inc, line 1232

This file contains misc functions for FlightPath

Code

function fp_strip_dangerous_protocols($uri) {
  static $allowed_protocols;

  if (!isset($allowed_protocols)) {
    $allowed_protocols = array_flip(array('ftp', 'http', 'https', 'irc', 'mailto', 'news', 'nntp', 'rtsp', 'sftp', 'ssh', 'tel', 'telnet', 'webcal'));
  }

  // Iteratively remove any invalid protocol found.
  do {
    $before = $uri;
    $colonpos = strpos($uri, ':');
    if ($colonpos > 0) {
      // We found a colon, possibly a protocol. Verify.
      $protocol = substr($uri, 0, $colonpos);
      // If a colon is preceded by a slash, question mark or hash, it cannot
      // possibly be part of the URL scheme. This must be a relative URL, which
      // inherits the (safe) protocol of the base document.
      if (preg_match('![/?#]!', $protocol)) {
        break;
      }
      // Check if this is a disallowed protocol. Per RFC2616, section 3.2.3
      // (URI Comparison) scheme comparison must be case-insensitive.
      if (!isset($allowed_protocols [strtolower($protocol)])) {
        $uri = substr($uri, $colonpos + 1);
      }
    }
  } while ($before != $uri);

  return $uri;
}