Customize Drupal Link module to only allow certain URLs

Customize the latest Link module (development release) to only allow URLs from prespecified domains. When users create new content and add a URL in the link field, they can only add URLs from certain domains. If they try to add URLs from domains that are not whitelisted, there will be an error that says "Please enter a recognized URL" For example. I only allow URLs from [login to view URL], [login to view URL], and squidoo.com. That means users can only add URLs from those sites. These URLs are okay: [login to view URL]*, *.[login to view URL]*, http://*.[login to view URL]*, [login to view URL], [login to view URL] These URLs would not be okay: [login to view URL], [login to view URL], [login to view URL] Once the module is tested to work, payment will be sent.