Ah, where to begin?
- $headers are the headers that are going to be sent back to the connection that made the request to the proxy. $message is either going to be an HTTP::Request or an HTTP::Response object. You specifically want to filter HTTP::Requests.
- What is $message->$headers->header supposed to do?
- You should be using HTTP::Proxy::HeaderFilter::simple. You may have been getting a message along the lines of "HTTP::Proxy::HeaderFilter cannot be used as a filter".
- You're going to need to patch HTTP::Proxy to rewrite the requested uri for you somewhere in HTTP::Proxy::serve_connections. Right now it's getting undef when it checks $req->uri->scheme. To change this up, you can have something along the lines of:
Please note that if you do not filter this request, your proxy will redirect to itself time and time again. Also, set your host to something.
$req->uri( $self->url . substr($req->uri,1) ) if $req->uri =~ m!^/!;
Hopefully something in here will help you.