Block registration by URL referrer?

Question

Is it possible to block user registration based on the referring URL? I have an open registration WP site (configured so users can post ads and events) and while I typically don't get a lot of spam registrations (there is a reCaptcha involved), I was listed on a site as an example of the capabilities of the theme I'm using, and it generates a lot of "test" type of traffic. I like the traffic, but I don't like people registering just to post false test posts just to see how the site works, so I'd ultimately like to simply block registration from that referring URL. Thanks!

Answer 1

You can use "register_post" hook that happens just before the user is saved to the database or you can use "register_form" hook and check the referring URL for a match and die();

Answer 2

Along with what Bainternet said, you could also set a session with that url in it, so if they go to your site and then go to another site/page and come back. You would still have that referring url there to check for.