Mainline peer discovery

get_peers.js

import DHT from 'bittorrent-dht'

const BOOTSTRAP = [
  { host: 'router.bittorrent.com', port: 6881 },
  { host: 'router.utorrent.com', port: 6881 },
  { host: 'dht.transmissionbt.com', port: 6881 },
  { host: 'router.nuh.dev', port: 6881 }
]

const infoHash = random()

const a = new DHT({ bootstrap: BOOTSTRAP }) // provider
const b = new DHT({ bootstrap: BOOTSTRAP }) // client

await new Promise((resolve, reject) => {
  a.announce(infoHash, 9090, (err, nodes) => {
    if (err) reject(err)
    resolve(nodes)
  })
})
console.log('announced', infoHash, "on", 9090)

await new Promise((resolve, reject) => {
  setTimeout(() => reject("GET_PEERS TIMEOUT"), 10000)

  console.log("Looking for peers on", infoHash)
  const start = Date.now()

  b.lookup(
    infoHash,
    (err, nodes) => {
      if (err) reject(err)
      console.log("Got responses from", nodes, "nodes")
      resolve(nodes)
    }
  )

  let end;

  b.on('peer', function(peer, _infoHash, from) {
    if (!end) {
      end = Date.now()
      console.log("Found first peer in", end - start, "ms")
    }

    console.log('found potential peer ' + peer.host + ':' + peer.port + ' through ' + from.address + ':' + from.port)
  })
})

a.destroy()
b.destroy()

function random() {
  return Buffer.from(
    new Array(4).fill(0).map(() => Math.random().toString(16).slice(2)).join(''),
    'hex'
  ).slice(0, 20)
}