@libp2p/mdns

Node.js libp2p mDNS discovery implementation for peer discovery

Table of contents

• Install
• Usage
• MDNS messages
• Contribute
• License
• Contribution

Install

$ npm i @libp2p/mdns

Usage

import { MDNS } from '@libp2p/mdns'

const mdns = new MDNS(options)

mdns.on('peer', (peerData) => {
  console.log('Found a peer in the local network', peerData.id.toString(), peerData.multiaddrs)
})

// Broadcast for 20 seconds
mdns.start()
setTimeout(() => mdns.stop(), 20 * 1000)

• options
  • peerId - PeerId to announce
  • multiaddrs - multiaddrs to announce
  • broadcast - (true/false) announce our presence through mDNS, default false
  • interval - query interval, default 10 * 1000 (10 seconds)
  • serviceTag - name of the service announce , default 'ipfs.local`
  • compat - enable/disable compatibility with go-libp2p-mdns, default true

MDNS messages

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

{ type: 'query',
  questions: [ { name: 'ipfs.local', type: 'PTR' } ]
}

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

[ { name: 'ipfs.local',
    type: 'PTR',
    class: 'IN',
    ttl: 120,
    data: 'QmNPubsDWATVngE3d5WDSNe7eVrFLuk38qb9t6vdLnu2aK.ipfs.local' },
  { name: 'QmNPubsDWATVngE3d5WDSNe7eVrFLuk38qb9t6vdLnu2aK.ipfs.local',
    type: 'SRV',
    class: 'IN',
    ttl: 120,
    data:
     { priority: 10,
       weight: 1,
       port: '20002',
       target: 'LAPTOP-G5LJ7VN9' } },
  { name: 'QmNPubsDWATVngE3d5WDSNe7eVrFLuk38qb9t6vdLnu2aK.ipfs.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' } ]

Contribute

The libp2p implementation in JavaScript is a work in progress. As such, there are a few things you can do right now to help out:

• Go through the modules and check out existing issues. This is especially useful for modules in active development. Some knowledge of IPFS/libp2p may be required, as well as the infrastructure behind it - for instance, you may need to read up on p2p and more complex operations like muxing to be able to help technically.
• Perform code reviews. More eyes will help a) speed the project along b) ensure quality and c) reduce possible future bugs.

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.