PHP variable passing between 3 domains

[iantresman]

If I start at www.domain.com and click on a link to a new domain (www.newdomain.com), I can check _SERVER["HTTP_REFERER"] to see that I have come from www.domain.com.

Now at www.newdomain.com, if I click on a link to www.anotherdomain.com, I will no longer be able to see that I started at www.domain.com since HTTP_REFERER now refers to www.newdomain.com

I'd like to be able to set a variable at www.domain.com which I can read at the third (and subsequent) domains.

I could add to my links something like this:
a href="http://www.newdomain.com?from=www.domain.com"
and then use _SERVER["QUERY_STRING"] to retrieve the information, and dynamically add it to all links on the current page, but it makes the variable visible, let alone inelegant.

Does anyone else know how to solve this? I thought it might be possible to create a variable that is passed via an HTTP headers? Or maybe a cookie, but can't these be disabled by browsers?

Regards,
Ian

[vitch2002]

You could pass it as a hidden field in a form with the form method="post". This will send it in the http headers.
It will however require you to track the variable throughout newdomain.com which will mean you can't use regular hyperlinks - only forms...
If you use a cookie it won't be visible between the different domains (i.e. a script at anotherdomain.com isn't allowed to see a cookie set at domain.com).
So I'm afraid I'm not alot of help...

[iantresman]

I think it's possible to emulate pressing a Submit button on clicking a link (with Javascript), but I'd rather have a non-Javascript solution if anyone can come up with one.