Node Streams2 UDPStream Implementation

udpstream.js

var dgram = require('dgram');
var _ = require('underscore');

var thumbs = {
  twiddle: function() {}
};

_.mixin({
  options: function(self, options, defaults) {
    if (options)
      _.extend(self, _.defaults(_.pick(options, _.keys(defaults)), defaults));
    else
      _.extend(self, defaults);
  }
});

var defaults = {
  address: '0.0.0.0',
  type: 'udp4',
  port: 12345,
  broadcast: null,
  multicast: null,
  multicastTTL: 1
};

var UDPStream = function(options) {
  if (!(this instanceof UDPStream))
    return new UDPStream(options);

  Duplex.call(this);

  _.options(this, options, defaults);

  this._socket = dgram.createSocket(this.type, setup.bind(this));
  this._socket.on('message', this.push.bind(this));
};

util.inherits(UDPStream, Duplex);

var setup = function() {
  if (this.multicast) {
    this._socket.addMembership(this.multicast);
    this._socket.setMulticastTTL(this.multicastTTL);

    this.destination = this.multicast;
  } else {
    // default to using broadcast if multicast address is not specified.
    this._socket.setBroadcast(true);

    // TODO: get the default broadcast address from os.networkInterfaces() (not currently returned)
    this.destination = this.broadcast || '255.255.255.255';
  }
};

UDPStream.prototype._read = function(size) {
  thumbs.twiddle();
};

UDPStream.prototype._write = function(chunk, encoding, callback) {
  this._socket.send(chunk, 0, chunk.length, this.port, this.destination);
};

module.exports = UDPStream;