Location: header does not seem to set HTTP_REFERER

Question

Before reading my question, please note: I am aware that HTTP_REFERER can be spoofed or disabled in the client browser. I don't care for my use case, and the browser I am testing with definitely passes referer information.

My question is this:

I create a file called page1.php:

<?php
header("Location: page2.php");

I create a second file called page2.php:

<?php
echo "Referred by \"" . $_SERVER['HTTP_REFERER'] . "\"";

then from my client browser I call:

http://test-me.co/page1.php

and I am expecting the resultant output from page2.php to be:

Referred by "http://test-me.co/page1.php"

but instead it displays with no referer information as follows:

Referred by ""

Can anyone please enlighten me as to why referer is empty?

thanks so much!

Answer 1

The referer contains the last actual page the user visited. If you enter URL example.com/a.html into your address bar which immediately redirects to /b.html, then you never really visited a.html at all; and before that there's no page you "came from".

To see any referer after a redirect the redirecting page must have been linked from somewhere, i.e.

a.html  --link-->  b.html  --redirect-->  c.html

Then in c.html you'd see a.html as the referer. If you're starting this chain at b.html, there is no referer.