Is there a way to get the page url a form was submitted from without to hide it (url) to the form?

I have different pages where users can add comments. I want to save the url of the page where the comment was made so that I can see it afterwards. Is this possible without hiding the the current url to the comment form? For example has the request() such a property? Or is hiding the url to the form the only way for that.

via Skeletor