signalk-server/lib/udpbroadcaster.js

An implementation of a [Signal K](http://signalk.org) server for boats.

"use strict";
/*
 * Copyright 2015 Teppo Kurki <teppo.kurki@iki.fi>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0

 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
    A quick hack to be able to broadcast Signal K or NMEA0183 data over UDP
    With modern Node one could figure out the broadcast address in
    simple cases where you have just one active interface.
    https://nodejs.org/api/os.html#os_os_networkinterfaces
*/
const Transform = require('stream').Transform;
const dgram = require('dgram');
function UdpBroadcaster() {
    Transform.call(this);
    let socket;
    this.udpSocket = socket = dgram.createSocket('udp4');
    socket.bind('192.168.1.255', function () {
        socket.setBroadcast(true);
    });
}
require('util').inherits(UdpBroadcaster, Transform);
UdpBroadcaster.prototype._transform = function (chunk, encoding, done) {
    try {
        const message = new Buffer(chunk.toString() + '\n');
        this.udpSocket.send(message, 0, message.length, 2000, '192.168.1.255');
    }
    catch (ex) {
        console.error(ex.stack);
    }
    this.push(chunk);
    done();
};
module.exports = UdpBroadcaster;