js-libp2p Pubsub Peer Discovery

A js-libp2p module that uses pubsub for interval broadcast peer discovery

Lead Maintainer

Jacob Heun.

Design

Flow

• When the discovery module is started by libp2p it subscribes to the discovery pubsub topic(s)
• It will immediately broadcast your peer data via pubsub and repeat the broadcast on the configured interval

Security Considerations

It is worth noting that this module does not include any message signing for broadcasts. The reason for this is that libp2p-pubsub supports message signing and enables it by default, which means the message you received has been verified to be from the originator, so we can trust that the peer information we have received is indeed from the peer who owns it. This doesn't mean the peer can't falsify its own records, but this module isn't currently concerned with that scenario.

Usage

Requirements

This module MUST be used on a libp2p node that is running Pubsub. If Pubsub does not exist, or is not running, this module will not work.

Usage in js-libp2p

See the js-libp2p configuration docs for how to include this module as a peer discovery module in js-libp2p.

If you are only interested in listening to the global pubsub topic the minimal configuration for using this with libp2p is:

const Libp2p = require('libp2p')
const Websockets = require('libp2p-websockets')
const MPLEX = require('libp2p-mplex')
const { NOISE } = require('libp2p-noise')
const GossipSub = require('libp2p-gossipsub')
const PubsubPeerDiscovery = require('libp2p-pubsub-peer-discovery')

const node = await Libp2p.create({
  modules: {
    transport: [Websockets], // Any libp2p transport(s) can be used
    streamMuxer: [MPLEX],
    connEncryption: [NOISE],
    pubsub: GossipSub, // Can also be `libp2p-floodsub` if desired
    peerDiscovery: [PubsubPeerDiscovery]
  }
})

Customizing Pubsub Peer Discovery

There are a few options you can use to customize Pubsub Peer Discovery. You can see the detailed options below.

// ... Other imports from above
const PubsubPeerDiscovery = require('libp2p-pubsub-peer-discovery')

// Custom topics
const topics = [
  `myApp._peer-discovery._p2p._pubsub`, // It's recommended but not required to extend the global space
  '_peer-discovery._p2p._pubsub' // Include if you want to participate in the global space
]

const node = await Libp2p.create({
  modules: { /* See 'Usage in js-libp2p' for this block */ },
  config: {
    peerDiscovery: {
      'PubsubPeerDiscovery': { // 'PubsubPeerDiscovery' is also available from the static property PubsubPeerDiscovery.tag
        interval: 10000,
        topics: topics, // defaults to ['_peer-discovery._p2p._pubsub']
        listenOnly: false
      }
    }
  }
})

Options

| Name | Type | Description | |------|------|-------------| | interval | number | How often (in ms), after initial broadcast, your node should broadcast your peer data. Default (10000ms)| | topics | Array<string> | An Array of topic strings. If set, the default topic will not be used and must be included explicitly here | | listenOnly | boolean | If true it will not broadcast peer data. Dont set this unless you have a specific reason to. Default (false) |

Default Topic

The default pubsub topic the module subscribes to is _peer-discovery._p2p._pubsub, which is also set on PubsubPeerDiscovery.TOPIC.

Contribute

Feel free to join in. All welcome. Open an issue!

This repository falls under the IPFS Code of Conduct.

License

MIT - Protocol Labs 2020