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bittorrent-tracker

Simple, robust, BitTorrent tracker (client & server) implementation

Node.js implementation of a BitTorrent tracker, client and server.

A BitTorrent tracker is a web service which responds to requests from BitTorrent clients. The requests include metrics from clients that help the tracker keep overall statistics about the torrent. The response includes a peer list that helps the client participate in the torrent swarm.

This module is used by WebTorrent.

features

• Includes client & server implementations
• Supports all mainstream tracker types:
  • HTTP trackers
  • UDP trackers (BEP 15)
  • WebTorrent trackers (BEP forthcoming)
• Supports ipv4 & ipv6
• Supports tracker "scrape" extension
• Robust and well-tested
  • Comprehensive test suite (runs entirely offline, so it's reliable)
  • Used by popular clients: WebTorrent, peerflix, and playback
• Tracker statistics available via web interface at /stats or JSON data at /stats.json

Also see bittorrent-dht.

Tracker stats

install

npm install bittorrent-tracker

usage

client

To connect to a tracker, just do this:

import Client from 'bittorrent-tracker'

const requiredOpts = {
  infoHash: new Buffer('012345678901234567890'), // hex string or Buffer
  peerId: new Buffer('01234567890123456789'), // hex string or Buffer
  announce: [], // list of tracker server urls
  port: 6881 // torrent client port, (in browser, optional)
}

const optionalOpts = {
  // RTCPeerConnection config object (only used in browser)
  rtcConfig: {},
  // User-Agent header for http requests
  userAgent: '',
  // Custom webrtc impl, useful in node to specify [wrtc](https://npmjs.com/package/wrtc)
  wrtc: {},
  getAnnounceOpts: function () {
    // Provide a callback that will be called whenever announce() is called
    // internally (on timer), or by the user
    return {
      uploaded: 0,
      downloaded: 0,
      left: 0,
      customParam: 'blah' // custom parameters supported
    }
  },
  // Proxy options (used to proxy requests in node)
  proxyOpts: {
      // For WSS trackers this is always a http.Agent
      // For UDP trackers this is an object of options for the Socks Connection
      // For HTTP trackers this is either an undici Agent if using Node16 or later, or http.Agent if using versions prior to Node 16, ex:
      // import Socks from 'socks'
      // proxyOpts.socksProxy = new Socks.Agent(optionsObject, isHttps)
      // or if using Node 16 or later
      // import { socksDispatcher } from 'fetch-socks'
      // proxyOpts.socksProxy = socksDispatcher(optionsObject)
      socksProxy: new SocksProxy(socksOptionsObject),
      // Populated with socksProxy if it's provided
      httpAgent: new http.Agent(agentOptionsObject),
      httpsAgent: new https.Agent(agentOptionsObject)
  },
}

const client = new Client(requiredOpts)

client.on('error', function (err) {
  // fatal client error!
  console.log(err.message)
})

client.on('warning', function (err) {
  // a tracker was unavailable or sent bad data to the client. you can probably ignore it
  console.log(err.message)
})

// start getting peers from the tracker
client.start()

client.on('update', function (data) {
  console.log('got an announce response from tracker: ' + data.announce)
  console.log('number of seeders in the swarm: ' + data.complete)
  console.log('number of leechers in the swarm: ' + data.incomplete)
})

client.once('peer', function (addr) {
  console.log('found a peer: ' + addr) // 85.10.239.191:48623
})

// announce that download has completed (and you are now a seeder)
client.complete()

// force a tracker announce. will trigger more 'update' events and maybe more 'peer' events
client.update()

// provide parameters to the tracker
client.update({
  uploaded: 0,
  downloaded: 0,
  left: 0,
  customParam: 'blah' // custom parameters supported
})

// stop getting peers from the tracker, gracefully leave the swarm
client.stop()

// ungracefully leave the swarm (without sending final 'stop' message)
client.destroy()

// scrape
client.scrape()

client.on('scrape', function (data) {
  console.log('got a scrape response from tracker: ' + data.announce)
  console.log('number of seeders in the swarm: ' + data.complete)
  console.log('number of leechers in the swarm: ' + data.incomplete)
  console.log('number of total downloads of this torrent: ' + data.downloaded)
})

server

To start a BitTorrent tracker server to track swarms of peers:

import { Server } from 'bittorrent-tracker'
// Or import Server from 'bittorrent-tracker/server'

const server = new Server({
  udp: true, // enable udp server? [default=true]
  http: true, // enable http server? [default=true]
  ws: true, // enable websocket server? [default=true]
  stats: true, // enable web-based statistics? [default=true]
  trustProxy: false, // enable trusting x-forwarded-for header for remote IP [default=false]
  filter: function (infoHash, params, cb) {
    // Blacklist/whitelist function for allowing/disallowing torrents. If this option is
    // omitted, all torrents are allowed. It is possible to interface with a database or
    // external system before deciding to allow/deny, because this function is async.

    // It is possible to block by peer id (whitelisting torrent clients) or by secret
    // key (private trackers). Full access to the original HTTP/UDP request parameters
    // are available in `params`.

    // This example only allows one torrent.

    const allowed = (infoHash === 'aaa67059ed6bd08362da625b3ae77f6f4a075aaa')
    if (allowed) {
      // If the callback is passed `null`, the torrent will be allowed.
      cb(null)
    } else {
      // If the callback is passed an `Error` object, the torrent will be disallowed
      // and the error's `message` property will be given as the reason.
      cb(new Error('disallowed torrent'))
    }
  }
})

// Internal http, udp, and websocket servers exposed as public properties.
server.http
server.udp
server.ws

server.on('error', function (err) {
  // fatal server error!
  console.log(err.message)
})

server.on('warning', function (err) {
  // client sent bad data. probably not a problem, just a buggy client.
  console.log(err.message)
})

server.on('listening', function () {
  // fired when all requested servers are listening

  // HTTP
  const httpAddr = server.http.address()
  const httpHost = httpAddr.address !== '::' ? httpAddr.address : 'localhost'
  const httpPort = httpAddr.port
  console.log(`HTTP tracker: http://${httpHost}:${httpPort}/announce`)

  // UDP
  const udpAddr = server.udp.address()
  const udpHost = udpAddr.address
  const udpPort = udpAddr.port
  console.log(`UDP tracker: udp://${udpHost}:${udpPort}`)

  // WS
  const wsAddr = server.ws.address()
  const wsHost = wsAddr.address !== '::' ? wsAddr.address : 'localhost'
  const wsPort = wsAddr.port
  console.log(`WebSocket tracker: ws://${wsHost}:${wsPort}`)

})


// start tracker server listening! Use 0 to listen on a random free port.
const port = 0
const hostname = "localhost"
server.listen(port, hostname, () => {
  // Do something on listening...
})

// listen for individual tracker messages from peers:

server.on('start', function (addr) {
  console.log('got start message from ' + addr)
})

server.on('complete', function (addr) {})
server.on('update', function (addr) {})
server.on('stop', function (addr) {})

// get info hashes for all torrents in the tracker server
Object.keys(server.torrents)

// get the number of seeders for a particular torrent
server.torrents[infoHash].complete

// get the number of leechers for a particular torrent
server.torrents[infoHash].incomplete

// get the peers who are in a particular torrent swarm
server.torrents[infoHash].peers

The http server will handle requests for the following paths: /announce, /scrape. Requests for other paths will not be handled.

multi scrape

Scraping multiple torrent info is possible with a static Client.scrape method:

import Client from 'bittorrent-tracker'
// Or import Client from 'bittorrent-tracker/client'

Client.scrape({ announce: announceUrl, infoHash: [ infoHash1, infoHash2 ]}, function (err, results) {
  results[infoHash1].announce
  results[infoHash1].infoHash
  results[infoHash1].complete
  results[infoHash1].incomplete
  results[infoHash1].downloaded

  // ...
})

command line

Install bittorrent-tracker globally:

$ npm install -g bittorrent-tracker

Easily start a tracker server:

$ bittorrent-tracker
http server listening on 8000
udp server listening on 8000
ws server listening on 8000

Lots of options:

$ bittorrent-tracker --help
  bittorrent-tracker - Start a bittorrent tracker server

  Usage:
    bittorrent-tracker [OPTIONS]

  If no --http, --udp, or --ws option is supplied, all tracker types will be started.

  Options:
    -p, --port [number]  change the port [default: 8000]
        --trust-proxy    trust 'x-forwarded-for' header from reverse proxy
        --interval       client announce interval (ms) [default: 600000]
        --http           enable http server
        --udp            enable udp server
        --ws             enable websocket server
    -q, --quiet          only show error output
    -s, --silent         show no output
    -v, --version        print the current version

license

MIT. Copyright (c) Feross Aboukhadijeh and WebTorrent, LLC.