$data = preg_replace("/(src|background|href)=(?:\"|')(?!http|ftp|https|about..?blank)(.*?)(?:\"|')/sim","\\1=http://$short/\\2",$data);
echo "<br>".nl2br(htmlspecialchars(preg_replace("/(src|background|href)=(?!\"|http|ftp|https|about..?blank)(.*?)/sim","\\1=http://bloody_short.ru/\\2",$data)));
Кажись так...