Posting to self from form

[eluser]Unknown[/eluser]
Is there a built in way in CI to post to the actual page/url that the user is on?
So to speak I've a login running, but the user can be at any page and still press the
login button since it's part of my mainpage, and so i just want to post back to whatever page he might be on and then my login will simply check if($this->input->post("loginForm") or similar.

I was thinking to use something similar to $_SERVER['REQUEST_URI'] unless there is a better way.