1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/lib/app.js Wed Aug 13 21:02:03 2014 +0200
1.3 @@ -0,0 +1,212 @@
1.4 +#! /usr/bin/env nodejs
1.5 +//
1.6 +// mDNSGw - Zero Configuration DNS Gateway for Mesh Networks
1.7 +// Copyright © 2014 Michael Schloh von Bennewitz <michael@schloh.com>
1.8 +//
1.9 +// Permission to use, copy, modify, and/or distribute this software for
1.10 +// any purpose with or without fee is hereby granted, provided that the
1.11 +// above copyright notice and this permission notice appear in all copies.
1.12 +//
1.13 +// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
1.14 +// WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
1.15 +// WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
1.16 +// AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
1.17 +// DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
1.18 +// PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
1.19 +// ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
1.20 +// THIS SOFTWARE.
1.21 +//
1.22 +// This file is part of mDNSGw, a Zero configuration DNS gateway
1.23 +// which can be found at http://dev.europalab.com/mdnsgw/
1.24 +//
1.25 +// app.js: ECMA JavaScript implementation
1.26 +//
1.27 +
1.28 +/***********************************************************
1.29 +| ____ _ _ ____ ____ |
1.30 +| _ __ ___ | _ \| \ | / ___| / ___|_ __ |
1.31 +| | '_ ` _ \| | | | \| \___ \| | _\ \ /\ / / |
1.32 +| | | | | | | |_| | |\ |___) | |_| |\ V V / |
1.33 +| |_| |_| |_|____/|_| \_|____/ \____| \_/\_/ |
1.34 +| |
1.35 +| Requirements: Redis server with standard configuration |
1.36 +| NodeJS and NPM modules (see package.json) |
1.37 +| |
1.38 +| Execute: To start this application, launch it with the |
1.39 +| script named fork.js: $ ./fork.js |
1.40 +| |
1.41 +| Support: http://list.europalab.com/mailman/mdnsgs/ |
1.42 +| |
1.43 +***********************************************************/
1.44 +
1.45 +// import module dependencies
1.46 +var mdnsinst = require('mdns');
1.47 +var redisdat = require('redis');
1.48 +var nameinst = require('native-dns');
1.49 +
1.50 +
1.51 +// install POSIX signal handlers
1.52 +process.on('SIGUSR2', function() {
1.53 + console.log('SIGUSR2: Dumping mDNSGw entries at', Date());
1.54 + rediscli.hgetall('hostnames', function (error, object) {console.dir(object);});
1.55 +});
1.56 +process.on('SIGHUP', function() {
1.57 + console.log('SIGHUP: Cleared all database entries at', Date());
1.58 + cleardb();
1.59 +});
1.60 +
1.61 +// instantiate a new redis client
1.62 +// http://www.rediscookbook.org/
1.63 +var rediscli = redisdat.createClient();
1.64 +rediscli.on('error', function (error) {
1.65 + console.log('Error ' + error);
1.66 +});
1.67 +
1.68 +// clear mDNS service keys
1.69 +function cleardb () {
1.70 + rediscli.del('hostnames');
1.71 + // this is not working unfortunately for the loop
1.72 + rediscli.keys('*', function (error, replies) {
1.73 + replies.forEach(function (reply, ident) {
1.74 + rediscli.del(reply, function (error, value) {
1.75 + if (error) throw(error);
1.76 + });
1.77 + });
1.78 + });
1.79 +}
1.80 +
1.81 +// scan all advertised mDNS service types
1.82 +cleardb(); // clear old data first
1.83 +var browsall = mdnsinst.browseThemAll();
1.84 +browsall.on('serviceUp', function(service) {
1.85 + // iterate through hosts and watch accordingly
1.86 + if (service.type.name.match(/^[a-zA-Z0-9\-]+$/)) { // mdns module hack
1.87 + if (service.type.protocol == 'tcp') {
1.88 + var browserv = mdnsinst.createBrowser(mdnsinst.tcp(service.type.name));
1.89 + }
1.90 + else if (service.type.protocol == 'udp') {
1.91 + var browserv = mdnsinst.createBrowser(mdnsinst.udp(service.type.name));
1.92 + }
1.93 + else if (service.type.protocol == 'sctp') {
1.94 + var browserv = mdnsinst.createBrowser(mdnsinst.sctp(service.type.name));
1.95 + }
1.96 + else throw(error);
1.97 +
1.98 + // common logic for all transports (TCP, UDP, SCTP, etcetera)
1.99 + browserv.on('serviceUp', function(service) {
1.100 + //console.log('service up: ', service);
1.101 + //{interfaceIndex: 2, type: {name: 'ssh', protocol: 'tcp', subtypes: [], fullyQualified: true}, replyDomain: 'local.', flags: 2, name: 'hostname-mich', networkInterface: 'eth0', fullname: 'hostname-mich._ssh._tcp.local.', host: 'hostname-mich.local.', port: 22, addresses: ['192.168.1.50']}
1.102 +
1.103 + // insert one or more IP addresses for each hostname.local.
1.104 + rediscli.hset('hostnames', service.host.replace(/\.$/, ''), service.addresses);
1.105 + });
1.106 + browserv.on('serviceDown', function(service) {
1.107 + console.log('service down: ', service);
1.108 + //FIXME: still need to selectively remove hosts
1.109 + });
1.110 + browserv.on('serviceChanged', function(service) {
1.111 + console.log('service changed: ', service);
1.112 + //FIXME: still need to selectively update hosts
1.113 + });
1.114 + browserv.start();
1.115 + }
1.116 +});
1.117 +browsall.start();
1.118 +
1.119 +// instantiate a new DNS server
1.120 +var nameserv = nameinst.createServer();
1.121 +
1.122 +nameserv.on('request', function (request, response) {
1.123 + //console.log(request)
1.124 +
1.125 + // ensure that requested hostname is present
1.126 + rediscli.hget('hostnames', request.question[0].name, function (error, value) {
1.127 + // handle unexpected errors
1.128 + if (error) throw(error);
1.129 +
1.130 + if (value) { // the db succeeded in finding a match
1.131 + // populate the DNS response with the chosen hostname
1.132 + rediscli.hkeys('hostnames', function (error, replies) {
1.133 + replies.forEach(function (host, index) {
1.134 + if (request.question[0].name == host) {
1.135 + rediscli.hget('hostnames', host, function (error, value) {
1.136 + // handle unexpected errors
1.137 + if (error) throw(error);
1.138 +
1.139 + // FIXME: still must handle multihomed hosts
1.140 + //// a host might have more than one address
1.141 + //value.forEach(function (addr, iter)
1.142 + // set the nameserver address
1.143 + response.answer.push(nameinst.A({
1.144 + name: host,
1.145 + address: value,
1.146 + ttl: 600,
1.147 + }));
1.148 + response.send();
1.149 + });
1.150 + }
1.151 + });
1.152 + });
1.153 + }
1.154 + else {
1.155 + response.answer.push(nameinst.A({
1.156 + name: request.question[0].name,
1.157 + address: '127.0.0.1',
1.158 + ttl: 600,
1.159 + }));
1.160 + response.send();
1.161 + }
1.162 + });
1.163 +});
1.164 +
1.165 +// DNS error handler logic
1.166 +nameserv.on('error', function (err, buff, req, res) {
1.167 + console.log('DNS problem: ', err.stack);
1.168 +});
1.169 +
1.170 +//// debug process user
1.171 +//console.log('Start.');
1.172 +//console.log(process.env.USER);
1.173 +//console.log(process.env.SUDO_USER);
1.174 +//console.log('Done.');
1.175 +//
1.176 +// <1024 must run privileged
1.177 +var nudpport = 53; // default DNS
1.178 +if (nudpport < 1024 && process.getuid() !== 0) {
1.179 + //console.log('Serving on port <1024 from an unprivileged user.\nChange to root if using a privileged port number.')
1.180 + throw new Error('Serving on port <1024 from an unprivileged user.')
1.181 +}
1.182 +
1.183 +// start the DNS process
1.184 +nameserv.serve(nudpport, function () {
1.185 + try {
1.186 + console.log('Starting mDNSGw on', Date());
1.187 + process.stdout.write('Old UID: ' + process.getuid() + ', Old GID: ' + process.getgid() + '... ');
1.188 + process.umask('0644');
1.189 + process.setgid('daemon');
1.190 + if (process.env.SUDO_USER)
1.191 + process.setuid(process.env.SUDO_USER);
1.192 + else
1.193 + process.setuid('daemon');
1.194 + console.log('New UID: ' + process.getuid() + ', New GID: ' + process.getgid());
1.195 + } catch (err) {
1.196 + console.log('Cowardly refusing to keep the process alive as root.');
1.197 + process.exit(1);
1.198 + }
1.199 +});
1.200 +
1.201 +//// debug print all key and value database entries
1.202 +//rediscli.hgetall('hostnames', function (error, object) {console.dir(object);});
1.203 +
1.204 +//// display stored mDNS service data entries
1.205 +//rediscli.hkeys('hostnames', function (error, replies) {
1.206 +// console.log(replies.length + ' replies:');
1.207 +// replies.forEach(function (reply, ident) {
1.208 +// console.log(' ' + ident + ': ' + reply);
1.209 +// });
1.210 +//});
1.211 +
1.212 +//// block executes on program termination
1.213 +//rediscli.quit(); // cleanup db connection
1.214 +//browserv.stop(); // zombie scope too bad
1.215 +//browsall.stop();
