find-peer.js

'use strict'

const { Buffer } = require('buffer')
const CID = require('cids')
const multiaddr = require('multiaddr')
const ndjson = require('iterable-ndjson')
const configure = require('../lib/configure')
const toIterable = require('stream-to-it/source')

module.exports = configure(({ ky }) => {
  return async function findPeer (peerId, options) {
    options = options || {}

    const searchParams = new URLSearchParams(options.searchParams)
    searchParams.set('arg', `${Buffer.isBuffer(peerId) ? new CID(peerId) : peerId}`)
    if (options.verbose != null) searchParams.set('verbose', options.verbose)

    const res = await ky.post('dht/findpeer', {
      timeout: options.timeout,
      signal: options.signal,
      headers: options.headers,
      searchParams
    })

    for await (const message of ndjson(toIterable(res.body))) {
      // 3 = QueryError
      // https://github.com/libp2p/go-libp2p-core/blob/6e566d10f4a5447317a66d64c7459954b969bdab/routing/query.go#L18
      // https://github.com/ipfs/go-ipfs/blob/eb11f569b064b960d1aba4b5b8ca155a3bd2cb21/core/commands/dht.go#L388-L389
      if (message.Type === 3) {
        throw new Error(message.Extra)
      }

      // 2 = FinalPeer
      // https://github.com/libp2p/go-libp2p-core/blob/6e566d10f4a5447317a66d64c7459954b969bdab/routing/query.go#L18
      if (message.Type === 2 && message.Responses) {
        // There will only be 1:
        // https://github.com/ipfs/go-ipfs/blob/eb11f569b064b960d1aba4b5b8ca155a3bd2cb21/core/commands/dht.go#L395-L396
        for (const { ID, Addrs } of message.Responses) {
          return {
            id: ID,
            addrs: (Addrs || []).map(a => multiaddr(a))
          }
        }
      }
    }

    throw new Error('not found')
  }
})