php防止xss攻击类

function clean_xss(&$string, $low = False)
{
    if (! is_array ( $string ))
    {
        $string = trim ( $string );
        $string = strip_tags ( $string );
        $string = htmlspecialchars ( $string );
        if ($low)
        {
            return True;
        }
        $string = str_replace ( array ('"', "\\", "'", "/", "..", "../", "./", "//" ), '', $string );
        $no = '/%0[0-8bcef]/';
        $string = preg_replace ( $no, '', $string );
        $no = '/%1[0-9a-f]/';
        $string = preg_replace ( $no, '', $string );
        $no = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S';
        $string = preg_replace ( $no, '', $string );
        return True;
    }
    $keys = array_keys ( $string );
    foreach ( $keys as $key )
    {
        clean_xss ( $string [$key] );
    }
}