Will this work? Is there a better way?
It tested ok in IIS, I have yet to try on my apache servers.

Problem:

Needed a custom 404 page with intelligent redirect based upon the referrer. Easy with Apache, not as easy with IIS.

Solution???:

PHP Code:

<?php 
 // ### Set $eREF to the Referring Page using QUERY_STRING (IIS) or REDIRECT_URL (apache)
 $eREF = !isset($_SERVER['REDIRECT_URL']) ? !isset($_SERVER['QUERY_STRING']) ? NULL : substr($_SERVER['QUERY_STRING'],4) : $_SERVER['REDIRECT_URL'] ;

 // ### Redirect Based on the Referring Page
 switch ($eREF) {
   case "http://host/badpage1.php":
     header( "HTTP/1.1 301 Moved Permanently" );
     header("location: http://host/goodpage1.php");
     exit;
   case "http://host/badpage2.php":
     header( "HTTP/1.1 301 Moved Permanently" );
     header("location: http://host/goodpage2.php");
     exit;
 }
?>

I should also be able to do something like:

PHP Code:

<?php
 // ### Redirect Based on Regexp
 $pattern = '/^([a-zA-Z0-9]*)$/i'
 if (preg_match_all($pattern, $eREF, $match) === 0)
   {
     header( "HTTP/1.1 301 Moved Permanently" );
    header("location: http://host/lookingfornumbers.php");
    exit;
   }
?>

I'm pretty sure you can use mod rewrite in apache to do what you are trying to do in PHP. It would make it much easier.

Thanks, only problem is I need a cross-platform solution.