Discuz! 帖子外链自动添加nofollow的方法

function parseurl($url, $text, $scheme) {        global $_G;        if(!$url && preg_match("/((https?|ftp|gopher|news|telnet|rtsp|mms|callto|bctp|thunder|qqdl|synacast){1}:////|www/.)[^/[/"']+/i", trim($text), $matches)) {                $url = $matches[0];                $length = 65;                if(strlen($url) > $length) {                        $text = substr($url, 0, intval($length * 0.5)).' ... '.substr($url, - intval($length * 0.3));                }        $url = nofollow($url);                return '<a href="'.(substr(strtolower($url), 0, 4) == 'www.' ? 'http://'.$url : $url).'" target="_blank">'.$text.'</a>';        } else {                $url = substr($url, 1);                if(substr(strtolower($url), 0, 4) == 'www.') {                        $url = 'http://'.$url;                }                $url = !$scheme ? $_G['siteurl'].$url : $url;                return '<a href="'.nofollow($url).'" target="_blank">'.$text.'</a>';        }}

function nofollow($url = ''){    $temp = array();    if( ! empty($url))    {        $temp = parse_url($url);        if(isset($temp['host']) && $temp['host'] != $_SERVER['HTTP_HOST'])        {            $url .= '" rel="nofollow"';        }    }    unset($temp);    return $url;}