How to detect presence of a domain name in a string of text, in php
<p>Ive been having a massive spamming issue on my site where people have been creating dozens of accounts every day, and spamming their site via URL shortening services (of which there are hundreds). Is there a function that will check for an existence of a link (without http:// or www.) which could be at any TLD, mostly the less-common ones.</p>

<p>Most of them are in a form of domain.ext/43tg34g</p>

<p>I would like to check the presence of domain.ext and prohibit new users from posting these. </p>
