I've tried searching this an innumerable amount of times with different word combinations, can't seem to crack it. Apparently I do not know the right terms in this situation.
When you come to my client's site, it needs to verify that you are 21 years of age of older. If you hit any page on the domain, it checks to see if the verified age cookie is set. If not, it takes you to a challenge page to give your date of birth, after which it forwards you to the index page (or a rejection page, if you answered incorrectly).
The problem I have run into is as follows: If a user finds any one of the pages in a search engine, after they pass the age test, how do I send them back to page they were originally requesting?
Example: User finds www.site.com/blog.php in google, after clicking the link, they are redirected to www.site.com/age_verify.php. After they pass the test, how do I send them back to www.site.com/blog.php instead of the default www.site.com?
I'm flummoxed. I'm pretty sure I'm dealing with HTTP referrers, but I don't know in what capacity.