How to get the previous url using PHP

问题:

Suppose my site's url is given as hyperlink on some page on the internet; that page could be anything on internet - blog, orkut, yahoo, even stackoverflow etc, and someone clicks on it,and visited my site. So can we know, using php, the previous url from which the visitor came to my page?

回答1:

Use the $_SERVER['HTTP_REFERER'] header, but bear in mind anybody can spoof it at anytime regardless of whether they clicked on a link.

回答2:

$_SERVER['HTTP_REFERER'] is the answer

回答3:

$_SERVER['HTTP_REFERER'] will give you incomplete url.

If you want http://bawse.3owl.com/jayz__magna_carta_holy_grail.php, $_SERVER['HTTP_REFERER'] will give you http://bawse.3owl.com/ only.

回答4:

I can't add a comment yet, so I wanted to share that HTTP_REFERER is not always sent.

Notice: Undefined index: HTTP_REFERER

回答5:

But you could make an own link for every fromurl.

Example: http://example.com?auth=holasite

In this example your site is: example.com

If somebody open that link it's give you the holasite value for the auth variable.

Then just $_GET['auth'] and you have the variable. But you should make a database to store it, and to authorize.

Like: $holasite = http://holasite.com (You could use mysql too..)

And just match it, and you have the url.

This method is a little bit more complicated, but it works. This method is good for a refferal system authentication. But where is the site name, you should write an id, and works with that id.