Validating a regcode against a username.

I have created a webform for prospective members to fill out and submit. I will be generating referral codes (registration codes) using the registration codes module that will then be assigned specifically to each current member. When they refer someone to the website, they will give that person their referral code. The new prospective member will enter the referring members name and corresponding code into the webform and submit it.

I want to validate the code against the member name. If it is an active code and it matches the member name, the form would successfully submit and they would be redirected to a confirmation page. If either code or name are invalid or don't match up, I would like them to be redirected to a page where they are asked to contact the referring member.

What is the best way to do this? Use Rules? Write my own module? I am new to coding. Any help with this would be greatly appreciated.

Thanks!