getting $r and env to reflect external ports

[Jonathan Swartz]

We've got a bunch of legacy code that uses $ENV{SCRIPT_URI},  
$ENV{SERVER_PORT}, $r->server->port and the like to generate external  
redirects.

This has worked fine til now, but now we are moving to a system where  
our external port != our internal port - the load balancer is going to  
forward ports 80 and ports 443 to non-secure ports 8080 and 8443 (so  
that we can run httpd as a non-root user.) Unfortunately, the code  
mentioned above will then use the wrong (internal) ports in the  
redirects. If I were using Apache reverse proxy, ProxyPassReverse  
would take care of this, but I'm not.

The legacy code is scattered in many files and will be difficult to  
change. Thus I'm wondering if there's an easy way to get %ENV and $r  
to reflect the external ports, without going through and changing each  
port-related $ENV and $r value by hand.

e.g. In the Apache code I see that the ENV vars are populated via  
ap_get_server_port - is there a way for me to hook in early enough  
that I can change this?

Thanks
Jon