Check entry page

[ts10]

I need to check the page a user come to this page from - because if it's not the login page, I need to send them to the login page. How can I check what the entry page is?

Thanks!

[LordShryku]

$_SERVER['HTTP_REFERER']

[ts10]

If I print that out, I get nothing at all. Do I have to do something to that to get the value?

Thanks!