Comments on: PHP predefined variables and URLs

Question: PHP predefined variables and URLs

lyam — Wed, 14 Nov 2007 05:10:07 -0800

I'm developing a custom 404 page using .htaccess to redirect to the 404.html. I'm trying to use PHP (via an include in the 404.html) to show the referring page (using $_SERVER['HTTP_REFERER']). This works fine. I'd also like to return the bad URL that originates the 404. Is this possible using PHP?

I've reviewed the documentation at php.net regarding predefined variables but I'm not seeing what I want. If it's not possible via PHP is it possible using any other technology? If so, any suggestions? I do not have access to the server configuration BTW.

Thanks.

By: malevolent

malevolent — Wed, 14 Nov 2007 05:57:55 -0800

On most servers you can use $_SERVER['REQUEST_URI'] to get the current page's URL relative to root, or use something like this to build the full URL. Whatever you use, make sure it's HTML-encoded before being displayed to avoid any potential XSS nastiness.
(I assume you're not actually doing an HTTP redirect, just rewriting the URL to point to 404.html internally? Otherwise the current page would be 404.html and the referer would be the page originating the error)

By: lyam

lyam — Wed, 14 Nov 2007 06:08:31 -0800

Well that explains why REQUEST_URI wasn't giving me the results I was after. Thanks for the heads up. I guess I need to be using mod_rewrite to to internally redirect?

By: malevolent

malevolent — Wed, 14 Nov 2007 08:16:25 -0800

If you define the 404 in htaccess with something like
ErrorDocument 404 /_errors/404.php
then the URL won't change and REQUEST_URI will be intact within 404.php

By: lyam

lyam — Wed, 14 Nov 2007 08:53:29 -0800

I've attempted exactly that. What happens is that when I use relative paths, I get the path name output to the screen. When I use an absolute path it works, however the URL does change to the 404.htm.

By: malevolent

malevolent — Wed, 14 Nov 2007 10:07:53 -0800

On my servers (local OS X MAMP and remote Linux), if I use something like
ErrorDocument 404 _errors/404.php
then yes, it just outputs the path, but if I add the slash at the start to specify a path relative to root then it works fine. As you've found, specifying a full URL results in a redirect.

By: lyam

lyam — Wed, 14 Nov 2007 10:18:11 -0800

Wow, I swear I tried that as well, but I must've been mistaken. All is well now. Thanks!