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vendor/ezyang/htmlpurifier/library/HTMLPurifier/AttrDef/CSS/URI.php 2.43 KB
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  <?php
  
  /**
   * Validates a URI in CSS syntax, which uses url('http://example.com')
   * @note While theoretically speaking a URI in a CSS document could
   *       be non-embedded, as of CSS2 there is no such usage so we're
   *       generalizing it. This may need to be changed in the future.
   * @warning Since HTMLPurifier_AttrDef_CSS blindly uses semicolons as
   *          the separator, you cannot put a literal semicolon in
   *          in the URI. Try percent encoding it, in that case.
   */
  class HTMLPurifier_AttrDef_CSS_URI extends HTMLPurifier_AttrDef_URI
  {
  
      public function __construct()
      {
          parent::__construct(true); // always embedded
      }
  
      /**
       * @param string $uri_string
       * @param HTMLPurifier_Config $config
       * @param HTMLPurifier_Context $context
       * @return bool|string
       */
      public function validate($uri_string, $config, $context)
      {
          // parse the URI out of the string and then pass it onto
          // the parent object
  
          $uri_string = $this->parseCDATA($uri_string);
          if (strpos($uri_string, 'url(') !== 0) {
              return false;
          }
          $uri_string = substr($uri_string, 4);
          $new_length = strlen($uri_string) - 1;
          if ($uri_string[$new_length] != ')') {
              return false;
          }
          $uri = trim(substr($uri_string, 0, $new_length));
  
          if (!empty($uri) && ($uri[0] == "'" || $uri[0] == '"')) {
              $quote = $uri[0];
              $new_length = strlen($uri) - 1;
              if ($uri[$new_length] !== $quote) {
                  return false;
              }
              $uri = substr($uri, 1, $new_length - 1);
          }
  
          $uri = $this->expandCSSEscape($uri);
  
          $result = parent::validate($uri, $config, $context);
  
          if ($result === false) {
              return false;
          }
  
          // extra sanity check; should have been done by URI
          $result = str_replace(array('"', "\\", "\n", "\x0c", "\r"), "", $result);
  
          // suspicious characters are ()'; we're going to percent encode
          // them for safety.
          $result = str_replace(array('(', ')', "'"), array('%28', '%29', '%27'), $result);
  
          // there's an extra bug where ampersands lose their escaping on
          // an innerHTML cycle, so a very unlucky query parameter could
          // then change the meaning of the URL.  Unfortunately, there's
          // not much we can do about that...
          return "url(\"$result\")";
      }
  }
  
  // vim: et sw=4 sts=4