为WordPress 文章中的链接自动添加 nofollow标签

add_filter('the_content', 'auto_nofollow');   function auto_nofollow($content) { //return stripslashes(wp_rel_nofollow($content));   return preg_replace_callback('/<a>]+/', 'auto_nofollow_callback', $content); }   function auto_nofollow_callback($matches) { $link = $matches[0]; $site_link = get_bloginfo('url');   if (strpos($link, 'rel') === false) { $link = preg_replace("%(href=S(?!$site_link))%i", 'rel="nofollow" $1', $link); } elseif (preg_match("%href=S(?!$site_link)%i", $link)) { $link = preg_replace('/rel=S(?!nofollow)S*/i', 'rel="nofollow"', $link); } return $link; }