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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
}
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
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