php如何防止utf-7 反射xss 漏洞。

<code>        $req = Yii::app()->request;
        $purifier = new CHtmlPurifier();
        $purifier->options = array(
            'URI.AllowedSchemes'=>array(
                'http' => true,
                'https' => true,
            )
        );
            $url = $purifier->purify($req->getParam('url'));</code>

<code>        $req = Yii::app()->request;
        $purifier = new CHtmlPurifier();
        $purifier->options = array(
            'URI.AllowedSchemes'=>array(
                'http' => true,
                'https' => true,
            )
        );
            $url = $purifier->purify($req->getParam('url'));</code>