Skip to content
Low level multicast-dns implementation in pure javascript
JavaScript
Branch: master
Clone or download

Latest commit

Latest commit 52bf467 Mar 26, 2020

Files

Permalink
Type Name Latest commit message Commit time
Failed to load latest commit information.
.gitignore support explicit bind argument Feb 14, 2020
.travis.yml Test against maintained node versinos (#57) Sep 12, 2018
LICENSE first commit Jan 8, 2015
README.md Upgrade to dns-packet 4.0.0 (#49) Feb 12, 2018
appveyor.yml Add support for appveyor (#58) Sep 12, 2018
cli.js make cli reply to rinfo port Sep 4, 2018
example.js Clean up example.js Jan 5, 2016
index.js on osx always choose en0 if we can Mar 26, 2020
package.json 7.2.2 Mar 26, 2020
test.js Upgrade to dns-packet 4.0.0 (#49) Feb 12, 2018

README.md

multicast-dns

Low level multicast-dns implementation in pure javascript

npm install multicast-dns

build status

Usage

var mdns = require('multicast-dns')()

mdns.on('response', function(response) {
  console.log('got a response packet:', response)
})

mdns.on('query', function(query) {
  console.log('got a query packet:', query)
})

// lets query for an A record for 'brunhilde.local'
mdns.query({
  questions:[{
    name: 'brunhilde.local',
    type: 'A'
  }]
})

Running the above (change brunhilde.local to your-own-hostname.local) will print an echo of the query packet first

got a query packet: { type: 'query',
  questions: [ { name: 'brunhilde.local', type: 'A', class: 1 } ],
  answers: [],
  authorities: [],
  additionals: [] }

And then a response packet

got a response packet: { type: 'response',
  questions: [],
  answers:
   [ { name: 'brunhilde.local',
       type: 'A',
       class: 'IN',
       ttl: 120,
       flush: true,
       data: '192.168.1.5' } ],
  authorities: [],
  additionals:
   [ { name: 'brunhilde.local',
       type: 'A',
       class: 'IN',
       ttl: 120,
       flush: true,
       data: '192.168.1.5' },
     { name: 'brunhilde.local',
       type: 'AAAA',
       class: 'IN',
       ttl: 120,
       flush: true,
       data: 'fe80::5ef9:38ff:fe8c:ceaa' } ] }

CLI

npm install -g multicast-dns
multicast-dns brunhilde.local
> 192.168.1.1

API

A packet has the following format

{
  questions: [{
    name:'brunhilde.local',
    type:'A'
  }],
  answers: [{
    name:'brunhilde.local',
    type:'A',
    ttl:seconds,
    data:(record type specific data)
  }],
  additionals: [
    (same format as answers)
  ],
  authorities: [
    (same format as answers)
  ]
}

Currently data from SRV, A, PTR, TXT, AAAA and HINFO records is passed

mdns = multicastdns([options])

Creates a new mdns instance. Options can contain the following

{
  multicast: true // use udp multicasting
  interface: '192.168.0.2' // explicitly specify a network interface. defaults to all
  port: 5353, // set the udp port
  ip: '224.0.0.251', // set the udp ip
  ttl: 255, // set the multicast ttl
  loopback: true, // receive your own packets
  reuseAddr: true // set the reuseAddr option when creating the socket (requires node >=0.11.13)
}

mdns.on('query', (packet, rinfo))

Emitted when a query packet is received.

mdns.on('query', function(query) {
  if (query.questions[0] && query.questions[0].name === 'brunhilde.local') {
    mdns.respond(someResponse) // see below
  }
})

mdns.on('response', (packet, rinfo))

Emitted when a response packet is received.

The response might not be a response to a query you send as this is the result of someone multicasting a response.

mdns.query(packet, [cb])

Send a dns query. The callback will be called when the packet was sent.

The following shorthands are equivalent

mdns.query('brunhilde.local', 'A')
mdns.query([{name:'brunhilde.local', type:'A'}])
mdns.query({
  questions: [{name:'brunhilde.local', type:'A'}]
})

mdns.respond(packet, [cb])

Send a dns response. The callback will be called when the packet was sent.

// reply with a SRV and a A record as an answer
mdns.respond({
  answers: [{
    name: 'my-service',
    type: 'SRV',
    data: {
      port:9999,
      weigth: 0,
      priority: 10,
      target: 'my-service.example.com'
    }
  }, {
    name: 'brunhilde.local',
    type: 'A',
    ttl: 300,
    data: '192.168.1.5'
  }]
})

The following shorthands are equivalent

mdns.respond([{name:'brunhilde.local', type:'A', data:'192.158.1.5'}])
mdns.respond({
  answers: [{name:'brunhilde.local', type:'A', data:'192.158.1.5'}]
})

mdns.destroy()

Destroy the mdns instance. Closes the udp socket.

Development

To start hacking on this module you can use this example to get started

git clone git://github.com/mafintosh/multicast-dns.git
npm install
node example.js
node cli.js $(hostname).local

License

MIT

You can’t perform that action at this time.