File

includes/misc.inc, line 608

This file contains misc functions for FlightPath

Code

function filter_xss_attributes($attr) {
  $attrarr = array();
  $mode = 0;
  $attrname = '';

  while (strlen($attr) != 0) {
    // Was the last operation successful?
    $working = 0;

    switch ($mode) {
      case 0:
        // Attribute name, href for instance.
        if (preg_match('/^([-a-zA-Z]+)/', $attr, $match)) {
          $attrname = strtolower($match [1]);
          $skip = ($attrname == 'style' || substr($attrname, 0, 2) == 'on');
          $working = $mode = 1;
          $attr = preg_replace('/^[-a-zA-Z]+/', '', $attr);
        }
        break;

      case 1:
        // Equals sign or valueless ("selected").
        if (preg_match('/^\s*=\s*/', $attr)) {
          $working = 1;
          $mode = 2;
          $attr = preg_replace('/^\s*=\s*/', '', $attr);
          break;
        }

        if (preg_match('/^\s+/', $attr)) {
          $working = 1;
          $mode = 0;
          if (!$skip) {
            $attrarr [] = $attrname;
          }
          $attr = preg_replace('/^\s+/', '', $attr);
        }
        break;

      case 2:
        // Attribute value, a URL after href= for instance.
        if (preg_match('/^"([^"]*)"(\s+|$)/', $attr, $match)) {
          $thisval = filter_xss_bad_protocol($match [1]);

          if (!$skip) {
            $attrarr [] = "$attrname=\"$thisval\"";
          }
          $working = 1;
          $mode = 0;
          $attr = preg_replace('/^"[^"]*"(\s+|$)/', '', $attr);
          break;
        }

        if (preg_match("/^'([^']*)'(\s+|$)/", $attr, $match)) {
          $thisval = filter_xss_bad_protocol($match [1]);

          if (!$skip) {
            $attrarr [] = "$attrname='$thisval'";
          }
          $working = 1;
          $mode = 0;
          $attr = preg_replace("/^'[^']*'(\s+|$)/", '', $attr);
          break;
        }

        if (preg_match("%^([^\s\"']+)(\s+|$)%", $attr, $match)) {
          $thisval = filter_xss_bad_protocol($match [1]);

          if (!$skip) {
            $attrarr [] = "$attrname=\"$thisval\"";
          }
          $working = 1;
          $mode = 0;
          $attr = preg_replace("%^[^\s\"']+(\s+|$)%", '', $attr);
        }
        break;
    }

    if ($working == 0) {
      // Not well formed; remove and try again.
      $attr = preg_replace('/
        ^
        (
        "[^"]*("|$)     # - a string that starts with a double quote, up until the next double quote or the end of the string
        |               # or
        \'[^\']*(\'|$)| # - a string that starts with a quote, up until the next quote or the end of the string
        |               # or
        \S              # - a non-whitespace character
        )*              # any number of the above three
        \s*             # any number of whitespaces
        /x', '', $attr);
      $mode = 0;
    }
  }

  // The attribute list ends with a valueless attribute like "selected".
  if ($mode == 1 && !$skip) {
    $attrarr [] = $attrname;
  }
  return $attrarr;
}