mDNSGw Sources: src/lib/app.js@f48fa3532729

     1 #! /usr/bin/env nodejs

     2 //

     3 //  mDNSGw - Zero Configuration DNS Gateway for Mesh Networks

     4 //  Copyright © 2014 Michael Schloh von Bennewitz <michael@schloh.com>

     5 //

     6 //  Permission to use, copy, modify, and/or distribute this software for

     7 //  any purpose with or without fee is hereby granted, provided that the

     8 //  above copyright notice and this permission notice appear in all copies.

     9 //

    10 //  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL

    11 //  WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED

    12 //  WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE

    13 //  AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL

    14 //  DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR

    15 //  PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS

    16 //  ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF

    17 //  THIS SOFTWARE.

    18 //

    19 //  This file is part of mDNSGw, a Zero configuration DNS gateway

    20 //  which can be found at http://dev.europalab.com/mdnsgw/

    21 //

    22 //  app.js: ECMA JavaScript implementation

    23 //

    25 /***********************************************************

    26 |                  ____  _   _ ____   ____                 |

    27 |        _ __ ___ |  _ \| \ | / ___| / ___|_      __       |

    28 |       | '_ ` _ \| | | |  \| \___ \| |  _\ \ /\ / /       |

    29 |       | | | | | | |_| | |\  |___) | |_| |\ V  V /        |

    30 |       |_| |_| |_|____/|_| \_|____/ \____| \_/\_/         |

    31 |                                                          |

    32 | Requirements: Redis server with standard configuration   |

    33 |               NodeJS and NPM modules (see package.json)  |

    34 |                                                          |

    35 | Execute: To start this application, launch it with the   |

    36 |          script named fork.js: $ ./fork.js               |

    37 |                                                          |

    38 | Support: http://list.europalab.com/mailman/mdnsgs/       |

    39 |                                                          |

    40 | Test: dig @nodeapp.host.tld A realhost.local             |

    41 |                                                          |

    42 ***********************************************************/

    44 // import module dependencies

    45 var mdnsinst = require('mdns');

    46 var redisdat = require('redis');

    47 var nameinst = require('native-dns');

    50 // install POSIX signal handlers

    51 process.on('SIGUSR2', function() {

    52   console.log('SIGUSR2: Dumping mDNSGw entries at', Date());

    53   rediscli.hgetall('hostnames', function (error, object) {console.dir(object);});

    54 });

    55 process.on('SIGHUP', function() {

    56   console.log('SIGHUP: Cleared all database entries at', Date());

    57   cleardb();

    58 });

    60 // format a date and time

    61 function getDateTime() {

    62     var date = new Date();

    63     var hour = date.getHours();

    64     hour = (hour < 10 ? '0' : '') + hour;

    65     var min  = date.getMinutes();

    66     min = (min < 10 ? '0' : '') + min;

    67     var sec  = date.getSeconds();

    68     sec = (sec < 10 ? '0' : '') + sec;

    69     var year = date.getFullYear();

    70     var month = date.getMonth() + 1;

    71     month = (month < 10 ? '0' : '') + month;

    72     var day  = date.getDate();

    73     day = (day < 10 ? '0' : '') + day;

    75     return year + '.' + month + '.' + day + '-' + hour + ':' + min + ':' + sec;

    76 }

    78 // instantiate a new redis client

    79 // http://www.rediscookbook.org/

    80 var rediscli = redisdat.createClient();

    81 rediscli.on('error', function (error) {

    82   console.log('Error ' + error);

    83 });

    85 // clear mDNS service keys

    86 function cleardb () {

    87   rediscli.del('hostnames');

    88   // this is not working unfortunately for the loop

    89   rediscli.keys('*', function (error, replies) {

    90     replies.forEach(function (reply, ident) {

    91       rediscli.del(reply, function (error, value) {

    92         if (error) throw(error);

    93       });

    94     });

    95   });

    96 }

    98 // scan all advertised mDNS service types

    99 cleardb(); // clear old data first

   100 var browsall = mdnsinst.browseThemAll();

   101 browsall.on('serviceUp', function(service) {

   102     // iterate through hosts and watch accordingly

   103     if (service.type.name.match(/^[a-zA-Z0-9\-]+$/)) { // mdns module hack

   104       if (service.type.protocol == 'tcp') {

   105         var browserv = mdnsinst.createBrowser(mdnsinst.tcp(service.type.name));

   106       }

   107       else if (service.type.protocol == 'udp') {

   108         var browserv = mdnsinst.createBrowser(mdnsinst.udp(service.type.name));

   109       }

   110       else if (service.type.protocol == 'sctp') {

   111         var browserv = mdnsinst.createBrowser(mdnsinst.sctp(service.type.name));

   112       }

   113       else throw(error);

   115       // common logic for all transports (TCP, UDP, SCTP, etcetera)

   116       browserv.on('serviceUp', function(service) {

   117         //console.log('service up: ', service);

   118         //{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']}

   119         rediscli.hget('hostnames', service.host.replace(/\.$/, ''), function (error, value) {

   120           // handle unexpected errors

   121           if (error) throw(error);

   123           // insert one or more IP addresses for each hostname.local.

   124           if (!value) { // only visit new (or with changed IPs) hosts

   125             var rcmulti = rediscli.multi(); // start a new transaction

   126             rcmulti.hsetnx('hostnames', service.host.replace(/\.$/, ''), service.addresses, function (error, nret) {

   127               if (nret === 1) // database wrote a new entry

   128                 console.log('    ' + getDateTime() + ' Detected host: ' + service.host.replace(/\.$/, '') + ' ' + service.addresses);

   129             }); //rcmulti.hsetnx();

   130             rcmulti.exec(); // flush transaction queue

   131           }

   132         });

   133       });

   134       browserv.on('serviceDown', function(service) {

   135         //console.log('service down: ', service);

   136         //FIXME: still need to selectively remove hosts

   137       });

   138       browserv.on('serviceChanged', function(service) {

   139         //console.log('service changed: ', service);

   140         //FIXME: still need to selectively update hosts

   141       });

   142       browserv.start();

   143     }

   144 });

   145 browsall.start();

   147 // instantiate a new DNS server

   148 var nameserv = nameinst.createServer();

   150 nameserv.on('request', function (request, response) {

   151   //console.log(request)

   153   // ensure that requested hostname is present

   154   rediscli.hget('hostnames', request.question[0].name, function (error, value) {

   155     // handle unexpected errors

   156     if (error) throw(error);

   158     if (value) { // the db succeeded in finding a match

   159       // FIXME: need to test incoming questions stripping trailing '.'

   160       // FIXME: and adding '.local' to handle cases of non FQDNs.

   161       // FIXME:   var found; // = {}; doesnt work unfortunately

   162       // FIXME:   if (request.question[0].name == host)

   163       // FIXME:     found = host;

   164       // FIXME:   else if (request.question[0].name + '.local' == host)

   165       // FIXME:     found = host.replace(/\.local$/, '');

   166       //

   167       // FIXME: replace silly new block with simple 'push(nameinst.A)

   168       // FIXME: since we already know that the host in question exists

   169       //

   170       // populate the DNS response with the chosen hostname

   171       rediscli.hkeys('hostnames', function (error, replies) {

   172           replies.forEach(function (host, index) {

   173             if (request.question[0].name == host) {

   174               rediscli.hget('hostnames', host, function (error, value) {

   175                 // handle unexpected errors

   176                 if (error) throw(error);

   178                 // FIXME: still must handle multihomed hosts

   179                 //// a host might have more than one address

   180                 //value.forEach(function (addr, iter)

   181                 // set the nameserver address

   182                 response.answer.push(nameinst.A({

   183                   name: host,

   184                   address: value,

   185                   ttl: 600,

   186                 }));

   187                 response.send();

   188               });

   189             }

   190           });

   191       });

   192     }

   193     else {

   194       response.answer.push(nameinst.A({

   195       name: request.question[0].name,

   196       address: '127.0.0.1',

   197       ttl: 600,

   198       }));

   199       response.send();

   200     }

   201   });

   202 });

   204 // DNS error handler logic

   205 nameserv.on('error', function (err, buff, req, res) {

   206   console.log('DNS problem: ', err.stack);

   207 });

   209 //// debug process user

   210 //console.log('Start.');

   211 //console.log(process.env.USER);

   212 //console.log(process.env.SUDO_USER);

   213 //console.log('Done.');

   214 //

   215 // <1024 must run privileged

   216 var nudpport = 53; // default DNS

   217 if (nudpport < 1024 && process.getuid() !== 0) {

   218   //console.log('Serving on port <1024 from an unprivileged user.\nChange to root if using a privileged port number.')

   219   throw new Error('Serving on port <1024 from an unprivileged user.')

   220 }

   222 // start the DNS process

   223 nameserv.serve(nudpport, function () {

   224   try {

   225     console.log('Starting mDNSGw on', Date());

   226     process.stdout.write('Old UID: ' + process.getuid() + ', Old GID: ' + process.getgid() + '... ');

   227     process.umask('0644');

   228     process.setgid('daemon');

   229     if (process.env.SUDO_USER)

   230       process.setuid(process.env.SUDO_USER);

   231     else

   232       process.setuid('daemon');

   233     console.log('New UID: ' + process.getuid() + ', New GID: ' + process.getgid());

   234   } catch (err) {

   235     console.log('Cowardly refusing to keep the process alive as root.');

   236     process.exit(1);

   237   }

   238 });

   240 //// debug print all key and value database entries

   241 //rediscli.hgetall('hostnames', function (error, object) {console.dir(object);});

   243 //// display stored mDNS service data entries

   244 //rediscli.hkeys('hostnames', function (error, replies) {

   245 //  console.log(replies.length + ' replies:');

   246 //  replies.forEach(function (reply, ident) {

   247 //    console.log('    ' + ident + ': ' + reply);

   248 //  });

   249 //});

   251 //// block executes on program termination

   252 //rediscli.quit();  // cleanup db connection

   253 //browserv.stop();  // zombie scope too bad

   254 //browsall.stop();

mDNSGw Sources / file revision

src/lib/app.js@f48fa3532729

src/lib/app.js