webtorrent

WebTorrent - Streaming torrent client for node and the browser

Warning: This is pre-alpha software. Nothing works yet. Watch/star to follow along with progress.

Ways to help

• Fix bugs, add features. Join #webtorrent on Freenode. Fix an open issue on this repo or one of the sub-modules. WebTorrent is an OPEN Open Source Project!
• Donations. If you believe in the vision, send bitcoin to 1B6aystcqu8fd6ejzpmMFMPRqH9b86iiwh or donate via Coinbase to support the project.

Report Issues

• Report New Issue
• View Open Issues

There is a single repo (webtorrent-issues) for managing publicly recognized issues with the webtorrent client, tracker, and website.

Features

• BitTorrent in your browser!
• No plugins (uses WebRTC Data Channels for peer-to-peer data)
• Streaming torrents (get important pieces first, then switch to rarest-first)
  • Into video tag with MediaSource API when possible (TODO)
  • Flash player with JS bridge for other media types (TODO)
• Works with .torrent files, magnet links, and info hashes
• Supports trackers
• Supports DHT (trackerless torrents) over WebRTC (TODO)
  • Extensions to DHT protocol to work over WebRTC
  • DHT nodes do "peer introductions" so WebRTC can work without a centralized signaling server
• Supports completely serverless, trackerless operation (TODO)

Project Goal

Build a browser BitTorrent client that requires no install (no plugin/extension/etc.) and fully-interoperates with the regular BitTorrent network. Use WebRTC Data Channels for peer-to-peer transport.

Since WebTorrent is web-first, it's simple for users who do not understand .torrent files, magnet links, NATs, etc. By making BitTorrent easier, it will be accessible to new swathes of users who were previously intimidated, confused, or unwilling to install a program on their machine to participate.

Usage

As of September 2014, WebTorrent works end-to-end. Here's how to give it a try:

var dragDrop = require('drag-drop/buffer')
var WebTorrent = require('webtorrent')

var client = new WebTorrent()

// when user drops files on the browser, create a new torrent and start seeding it!
dragDrop('body', function (files) {
  client.seed(files, onTorrent)
})

function onTorrent (torrent) {
  console.log('Torrent info hash: ' + torrent.infoHash)

  // go through each file in the torrent, create a link to it, and add it to the DOM
  torrent.files.forEach(function (file) {
    file.createReadStream().pipe(concat(function (buf) {
      var a = document.createElement('a')
      a.download = file.name
      a.href = URL.createObjectURL(new Blob([ buf ]))
      a.textContent = 'download ' + file.name
      document.body.appendChild(a)
    }))
  })
}

// call this function to download a torrent!
function download (infoHash) {
  client.download({
    infoHash: infoHash,
    announce: [ 'wss://tracker.webtorrent.io' ]
  }, onTorrent)
}

Please share feedback!

Modules

Most of the active development is happening inside of small npm modules which are used by WebTorrent. These are the modules I am writing to make WebTorrent work:

module	tests	version	description
webtorrent			torrent client (this module)
addr-to-ip-port			cache for addr->ip:port
bittorrent-client			access torrents as stream
bittorrent-dht			bittorrent dht client
bittorrent-peerid			identify client name/version
bittorrent-protocol			bittorrent protocol stream
bittorrent-swarm			bittorrent connection manager
bittorrent-tracker			bittorrent tracker server/client
buffer			node buffer api for the browser
create-torrent			create .torrent files
ip-set			efficient mutable ip set
load-ip-set			load ip sets
magnet-uri			parse magnet uris
parse-torrent			parse torrent identifiers
parse-torrent-file			parse .torrent files
simple-peer			webrtc wrapper api
simple-websocket			websocket wrapper api
string2compact			convert 'hostname:port' to compact
torrent-discovery			find peers via dht and tracker
typedarray-to-buffer			efficient buffer creation
ut_metadata			get metadata for magnet uris (ext)
ut_pex			peer discovery (ext)
webtorrent-swarm			webtorrent connection management
webtorrent-tracker			webtorrent tracker server/client

Todo:

• compress-sdp (compress sdp messages to lighten load on webtorrent trackers & dht)
• protocol extension: protocol encryption
• protocol extension: µTP
• protocol extension: UPnP and NAT-PMP port forwarding
• protocol extension: webseed support
• webtorrent-dht

The Node Way™

"When applications are done well, they are just the really application-specific, brackish residue that can't be so easily abstracted away. All the nice, reusable components sublimate away onto github and npm where everybody can collaborate to advance the commons." — substack from "how I write modules"

Interoperability with BitTorrent

Problem: WebTorrent clients and normal BitTorrent clients cannot directly connect because WebRTC cannot open UDP/TCP sockets. This is a security restriction on WebRTC that is unlikely to change. So, how do we get content into the WebTorrent network?

Best solution: Mainstream BitTorrent clients add support for WebTorrent. Basically, normal clients implement WebRTC so that WebTorrent clients can directly connect to them. (This could happen once WebTorrent has a lot of users.)

Good solution: Users who want to download torrents that aren't yet seeded by any WebTorrent users need to install a "hybrid client" that implements WebTorrent and BitTorrent. This can be implemented as a native torrent client that bridges the two networks like this:

• Hybrid clients can seed+leech from both WebTorrent and BitTorrent users.
• Hybrid clients are DHT nodes in both the WebTorrent and BitTorrent DHTs.
• The first time a hybrid client downloads a torrent that no other WebTorrent clients are seeding, they become the first WebTorrent seeder. (They essentially "bring" the file into the WebTorrent network).
• Important note: Hybrid clients never download torrents on behalf of other users. That would be a terrible idea.
• Until BitTorrent clients support WebTorrent, "pure" WebTorrent clients can only download from other WebTorrent clients.

WebTorrent vs BitTorrent

• WebTorrent is slower at finding peers since "DHT over WebRTC" requires multiple roundtrips for peer introductions. (This is a requirement of WebRTC signaling - no way around this)
• WebTorrent peers must keep their browser tab open to seed (Show UI to encourage seeding back at least 2x)
• Slower piece verification (SHA1) (max 2MB/s with web worker pool, Web Crypto API will bring huge speed-up when it's finally ready)
• WebTorrent bootstrap DHT node does a bit more work than a BitTorrent one since it must do WebRTC signaling. (Not a huge deal)

Todo for basic bitorrent client as node.js command line app

• Use UDP/TCP APIs
• Support DHT
• Support peer wire protocol
• Support magnet links (fetching .torrent from network)
• Basic UI
• Fetching logic
• Large file saving (downloading in-memory for now, later IndexedDB/FileSystem API)
• Streaming video
  • HTTP stream to VLC, like peerflix

Todo for webtorrent

• DHT over WebRTC (add new method for peer introduction)
  • Use bootstrap server for initial introduction
  • POST endpoint for sending offer/getting answer
• Easy torrent creation
• UPnP or NAT-PMP (so the hybrid client can get listed in peers' routing tables)
• Streaming video
  • MediaSource into video tag
  • Flash player for other media types

Get started

git clone https://github.com/feross/webtorrent.git
cd webtorrent
npm install
npm start

Chromebook users

Chromebooks are set to refuse all incoming connections by default. To change this, run:

sudo iptables -P INPUT ACCEPT

Contributors

WebTorrent is only possible due to the excellent work of the following contributors:

Feross Aboukhadijeh	GitHub/feross	Twitter/@feross
Daniel Posch	GitHub/dcposch	Twitter/@dcposch
John Hiesey	GitHub/jhiesey	Twitter/@jhiesey
Travis Fischer	GitHub/fisch0920	Twitter/@fisch0920
Astro	GitHub/astro	Twitter/@astro1138
Iván Todorovich	GitHub/ivantodorovich	Twitter/@ivantodorovich
Mathias Buus	GitHub/mafintosh	Twitter/@mafintosh
Bob Ren	GitHub/bobrenjc93	Twitter/@bobrenjc93

Talks about WebTorrent

• WebTorrent: Bringing BitTorrent to the Web with WebRTC (CraftConf) (April 2014, progress update on WebTorrent)
• WebRTC Black Magic (RealtimeConf) (October 2013, where I first shared the idea for WebTorrent (skip to end for WebTorrent))

License

MIT. Copyright (c) Feross Aboukhadijeh.