@libp2p/mdns

Node.js libp2p mDNS discovery implementation for peer discovery

About

A peer discover mechanism that uses mDNS to discover peers on the local network.

Example - Use with libp2p

import { createLibp2p } from 'libp2p'
import { mdns } from '@libp2p/mdns'

const libp2p = await createLibp2p({
  peerDiscovery: [
    mdns()
  ]
})

libp2p.addEventListener('peer:discovery', (evt) => {
  libp2p.dial(evt.detail.multiaddrs) // dial discovered peers
  console.log('found peer: ', evt.detail.toString())
})

MDNS messages

A query is sent to discover the libp2p nodes on the local network

{
   "type": "query",
   "questions": [{
     "name": "_p2p._udp.local",
     "type": "PTR"
   }]
}

When a query is detected, each libp2p node sends an answer about itself

[{
  "name": "_p2p._udp.local",
  "type": "PTR",
  "class": "IN",
  "ttl": 120,
  "data": "QmNPubsDWATVngE3d5WDSNe7eVrFLuk38qb9t6vdLnu2aK._p2p._udp.local"
}, {
  "name": "QmNPubsDWATVngE3d5WDSNe7eVrFLuk38qb9t6vdLnu2aK._p2p._udp.local",
  "type": "SRV",
  "class": "IN",
  "ttl": 120,
  "data": {
    "priority": 10,
    "weight": 1,
    "port": "20002",
    "target": "LAPTOP-G5LJ7VN9"
  }
}, {
  "name": "QmNPubsDWATVngE3d5WDSNe7eVrFLuk38qb9t6vdLnu2aK._p2p._udp.local",
  "type": "TXT",
  "class": "IN",
  "ttl": 120,
  "data": ["QmNPubsDWATVngE3d5WDSNe7eVrFLuk38qb9t6vdLnu2aK"]
}, {
  "name": "LAPTOP-G5LJ7VN9",
  "type": "A",
  "class": "IN",
  "ttl": 120,
  "data": "127.0.0.1"
}, {
  "name": "LAPTOP-G5LJ7VN9",
  "type": "AAAA",
  "class": "IN",
  "ttl": 120,
  "data": "::1"
}]

Install

$ npm i @libp2p/mdns

API Docs

• https://libp2p.github.io/js-libp2p/modules/_libp2p_mdns.html

License

Licensed under either of

• Apache 2.0, (LICENSE-APACHE / http://www.apache.org/licenses/LICENSE-2.0)
• MIT (LICENSE-MIT / http://opensource.org/licenses/MIT)

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.