211 lines
4.1 KiB
Markdown
211 lines
4.1 KiB
Markdown
# multicast-dns
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Low level multicast-dns implementation in pure javascript
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```
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npm install multicast-dns
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```
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[](http://travis-ci.org/mafintosh/multicast-dns)
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## Usage
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``` js
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var mdns = require('multicast-dns')()
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mdns.on('response', function(response) {
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console.log('got a response packet:', response)
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})
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mdns.on('query', function(query) {
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console.log('got a query packet:', query)
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})
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// lets query for an A record for 'brunhilde.local'
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mdns.query({
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questions:[{
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name: 'brunhilde.local',
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type: 'A'
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}]
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})
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```
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Running the above (change `brunhilde.local` to `your-own-hostname.local`) will print an echo of the query packet first
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``` js
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got a query packet: { type: 'query',
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questions: [ { name: 'brunhilde.local', type: 'A', class: 1 } ],
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answers: [],
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authorities: [],
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additionals: [] }
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```
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And then a response packet
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``` js
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got a response packet: { type: 'response',
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questions: [],
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answers:
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[ { name: 'brunhilde.local',
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type: 'A',
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class: 'IN',
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ttl: 120,
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flush: true,
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data: '192.168.1.5' } ],
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authorities: [],
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additionals:
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[ { name: 'brunhilde.local',
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type: 'A',
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class: 'IN',
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ttl: 120,
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flush: true,
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data: '192.168.1.5' },
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{ name: 'brunhilde.local',
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type: 'AAAA',
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class: 'IN',
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ttl: 120,
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flush: true,
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data: 'fe80::5ef9:38ff:fe8c:ceaa' } ] }
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```
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# CLI
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```
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npm install -g multicast-dns
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```
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```
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multicast-dns brunhilde.local
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> 192.168.1.1
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```
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# API
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A packet has the following format
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``` js
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{
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questions: [{
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name: 'brunhilde.local',
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type: 'A'
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}],
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answers: [{
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name: 'brunhilde.local',
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type: 'A',
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ttl: seconds,
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data: (record type specific data)
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}],
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additionals: [
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(same format as answers)
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],
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authorities: [
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(same format as answers)
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]
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}
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```
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Currently data from `SRV`, `A`, `PTR`, `TXT`, `AAAA` and `HINFO` records is passed
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#### `mdns = multicastdns([options])`
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Creates a new `mdns` instance. Options can contain the following
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``` js
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{
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multicast: true // use udp multicasting
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interface: '192.168.0.2' // explicitly specify a network interface. defaults to all
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port: 5353, // set the udp port
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ip: '224.0.0.251', // set the udp ip
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ttl: 255, // set the multicast ttl
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loopback: true, // receive your own packets
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reuseAddr: true // set the reuseAddr option when creating the socket (requires node >=0.11.13)
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}
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```
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#### `mdns.on('query', (packet, rinfo))`
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Emitted when a query packet is received.
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``` js
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mdns.on('query', function(query) {
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if (query.questions[0] && query.questions[0].name === 'brunhilde.local') {
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mdns.respond(someResponse) // see below
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}
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})
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```
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#### `mdns.on('response', (packet, rinfo))`
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Emitted when a response packet is received.
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The response might not be a response to a query you send as this
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is the result of someone multicasting a response.
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#### `mdns.query(packet, [cb])`
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Send a dns query. The callback will be called when the packet was sent.
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The following shorthands are equivalent
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``` js
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mdns.query('brunhilde.local', 'A')
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mdns.query([{name:'brunhilde.local', type:'A'}])
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mdns.query({
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questions: [{name:'brunhilde.local', type:'A'}]
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})
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```
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#### `mdns.respond(packet, [cb])`
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Send a dns response. The callback will be called when the packet was sent.
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``` js
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// reply with a SRV and a A record as an answer
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mdns.respond({
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answers: [{
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name: 'my-service',
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type: 'SRV',
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data: {
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port: 9999,
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weight: 0,
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priority: 10,
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target: 'my-service.example.com'
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}
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}, {
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name: 'brunhilde.local',
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type: 'A',
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ttl: 300,
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data: '192.168.1.5'
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}]
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})
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```
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The following shorthands are equivalent
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``` js
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mdns.respond([{name:'brunhilde.local', type:'A', data:'192.158.1.5'}])
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mdns.respond({
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answers: [{name:'brunhilde.local', type:'A', data:'192.158.1.5'}]
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})
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```
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#### `mdns.destroy()`
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Destroy the mdns instance. Closes the udp socket.
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# Development
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To start hacking on this module you can use this example to get started
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```
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git clone git://github.com/mafintosh/multicast-dns.git
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npm install
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node example.js
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node cli.js $(hostname).local
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```
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## License
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MIT
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