Detect Domain Change? - php

Question

Is it possible to detect source of web forwarding?
For example,
Domain A redirects to Domain B where Domain B has PHP hosting?
Basically I would like something like the following:
if ($was_redirected_from_domain_a) { ... }

Answer 1

As #MoarCodePlz and #Christopher Armstrong point out, $_SERVER["HTTP_REFERER"] is the solution.
However, in your specific case, two redirects take place:
http://fhc.quickmediasolutions.com/image/-1457172086.png
This way, the original referrer info is lost. You will need to disable the second redirect, and run your PHP in my-art-gallery.co.uk's index page.
Update after seeing the phpinfo() output:
$_SERVER["HTTP_REFER"] is indeed completely non-existent.
I suspect the culprit is this configuration setting:
suhosin.server.strip = On
your hosting company is running the Suhosin PHP patch, which allows removing certain data from the PHP page for enhanced security. You may need to ask them to activate HTTP_REFERER.
The only other way would be redirecting domain A to something like
domainb.co.uk/index.php?camefrom=domainA
You could then fetch the domainA argument through $_GET["camefrom"] - if the hosting provider's control panel allows that sort of redirection.

Answer 2

What you need to look at is known as the url referrer of the page. The url referrer is the url from which the current user made it to the site. Be careful, though, as the url referrer will be nonexistent if the user opened up a tab and simply typed in the url.
The url referrer should be able to be found using the following:
$myVar = $_SERVER['HTTP_REFERER'];

Answer 3

As Pekka said, it depends on how the user was forwarded. Try checking the $_SERVER['http_referrer'] value:
if ($_SERVER['HTTP_REFERER'] == 'mydomain.com/mypage'){
echo 'Came from mydomain';
}

Answer 4

$_SERVER["HTTP_REFERER"] is not a reliable solution. There are different cases where it does not work.
HTTP_REFERER does not contain the URL of the page that redirected, but the URL of the page where the user clicked.
E.g. On the page example.com is a link to t.co/somelink, which redirects to yoursite.com.
$_SERVER["HTTP_REFER"] will contain http://example.com, and there is no way to know that your visitor was redirected on your site from a twitter short URL.
The only way to know that the user came from your twitter link, is to include a $_GET parameter, like already proposed: Let the link t.co/somelink redirect to yoursite.com/?camefrom=twitter.