PHP (Update Block TLDS Module To Include Subdomains & Update Broken Captcha Module)

General information for the website: Proxy List Advertisement Site
Kind of development: Customization of existing website
Num. of web pages/modules: 2
Description of requirements/features: I have "submit proxy section"

http://www.top-proxies.co.uk/submit.php

I have a backend module in place at the moment which blocks certain TLD's it works in that case but my site is getting plauged with subdomain.coms and I need those blocked.

I have come to the decission that all SubDomains bust be blocked by default.

I believe it can be achieved using something similar to this:

preg_match("/[a-z0-9\-]{1,63}\.[a-z\.]{2,6}$/", parse_url($_POST["domain"], PHP_URL_HOST), $_domain_tld);
$domain = $_domain_tld[0];

that way http://somefuckedupdomain.google.com is the extact same as http://www.google.com

so it must automatically block subdomains of any sort.

second task is to update the captcha module using any other captcha tool and rebuild it into the Captcha module.

Overall I see this being about 2-3 hours work.
Similar urls: http://www.top-proxies.co.uk
Extra notes: Finer details of jobs including logins etc will be given on proposals.