Node.js - help intercepting packets

Question

I have the following Node.js proxy (http://www.catonmat.net/http-proxy-in-nodejs/) which I can print out packets from:

var http = require('http');
var util=require('util');
var net=require('net');
var context=require('zmq');

http.createServer(function(request, response) {
    var proxy=http.createClient(80,request.headers['host']);
    var proxy_request=proxy.request(request.method,request.url,request.headers);

    proxy_request.addListener('response',function (proxy_response){
        response.writeHead(proxy_response.statusCode,proxy_response.headers);

        proxy_response.addListener('data',function(chunk){
                    util.puts(chunk);   //ok, here is the HTTP body content that I'm interested in...
                    response.write(chunk,'binary');
        });
        proxy_response.addListener('end',function(){
            util.puts("end");
            response.end();
        });

    });


    request.addListener('close',function(){
        //util.puts("close");
    });
    request.addListener('data',function(chunk){
        //util.puts("data");
        proxy_request.write(chunk,'binary');
    });
    request.addListener('end',function(){
        //util.puts("end");
        proxy_request.end();
    });
}).listen(8080);

If you point your browser at 127.0.0.1:8080, I can see traffic going through the proxy as expected.

Now, what I'm trying to do is send the packet to another process running on the machine for further processing (the other process is a C program). This is done by using an IPC descriptor (ipc://myipc.ipc). The C program watches this IPC descriptor and outputs modified packets.

Here is the Node.js code I have to do this:

var requester=context.socket('req');
requester.connect("ipc://myipc.ipc");
requester.on("message",function(reply) {
    util.puts("Received reply: "+reply);
    requester.close();
});
requester.send(chunk);

Modified packets are being sent back from the C program as expected and they are available in the requester.on('message',function(reply){...}); callback.

My question is: how do I send the modified packets to response.write([modified packet],'binary')? I've tried this:

    ...
    proxy_response.addListener('data',function(chunk){
        util.puts(chunk);   //prints out the packet I'm interested in
        var requester=context.socket('req');
        requester.connect("ipc://myipc.ipc");
        requester.on("message",function(reply) {
            util.puts("Received reply: "+reply);
            response.write(reply,'binary');
            requester.close();
        });
        requester.send(chunk);
    });
    ...

But it won't work. It's as if the ordering of the packets is getting mixed up along the way. If I go to www.xlhi.com, it works fine because there is just a single request-response from the site. However, if I go to www.google.com (a site with multiple requests), the site won't load and I get content encoding errors.

I have callback spaghetti and it's getting very hard to make sense of what's going on in my program. I've looked at trying to make synchronous calls to zeromq to no avail. I'm now considering the use of futures.

If anyone has any insight, it's greatly appreciated.