Simple Node.js load balancer

loadbalancer.js

var net = require('net');

var globalConnectionCount = 0;

module.exports = function(srcPort, dstMaps) {
  var roundRobinIndex = 0;

  var balancer = net.createServer(function (inboundSocket) {
    var cnx = globalConnectionCount++ + ': ';
    var connected = false;
    var buffers = new Array();

    // new proxy per connection
    var dstMap = dstMaps[roundRobinIndex++];
    var dst = dstMap['host'] + ':' + dstMap['port'];
    roundRobinIndex = roundRobinIndex % dstMaps.length;

    console.log(cnx + ' ---> [] ---> ' + dst + ' new');

    // create and configure new outbound socket to connect to chosen destination
    var outboundSocket = new net.Socket();
    outboundSocket.connect(parseInt(dstMap['port']), dstMap['host'], function () {
      connected = true;
      if (buffers.length > 0) {
        for (i = 0; i < buffers.length; i++) {        
        outboundSocket.write(buffers[i]);
        }
      }
    }).on("error", function (e) {
      console.log(cnx + ' ---> [] -X-> ' + dst + ' error: ' + e);
      inboundSocket.end();
    }).on('data', function (data) {
      inboundSocket.write(data);   
    }).on("close", function(had_error) {
      console.log(cnx + ' ---> []  |-> ' + dst + ' close (had_error:' + had_error + ')');
      inboundSocket.end();
    });

    // configure inbound socket to connect to chosen destination
    inboundSocket.on("error", function (e) {
      console.log(cnx + ' -X-> [] ---> ' + dst + ' error: ' + e);
      outboundSocket.end();
    }).on("data", function (data) {
      if (connected) {
        outboundSocket.write(data);
      } else {
        buffers[buffers.length] = data;
      }
    }).on("close", function(had_error) {
      console.log(cnx + ' -|   [] ---> ' + dst + ' close (had_error:' + had_error + ')');
      outboundSocket.end();
      outboundSocket.destroy();
    });
  });

  balancer.listen(srcPort);
  console.log("Listening for TCP connections on:", srcPort);
};

Sample usage lb.js:

var lb = require('./loadbalancer.js')

var portMappings = {
  8080: [ {host:'localhost', port:80},
          {host:'shadow.local', port:80} ],
  8443: [ {host:'localhost', port:443},
          {host:'shadow.local', port:443} ]
};

for(var srcPort in portMappings) {
  lb(srcPort, portMappings[srcPort]);
}

Should be launched with:

$ node lb.js
Listening for TCP connections on 8080
Listening for TCP connections on 8443