Ttorrent, a Java implementation of the BitTorrent protocol

Description

Ttorrent is a pure-Java implementation of the BitTorrent protocol, providing a BitTorrent tracker, a BitTorrent client and the related Torrent metainfo files creation and parsing capabilities. It is designed to be embedded into larger applications, but its components can also be used as standalone programs.

This fork of ttorrent is a complete structural overhaul for correctness, improved performance using Netty, vastly reduced memory consumption, monitoring and metrics, and optional integration with Spring Framework and Jetty.

Ttorrent supports the following BEPs (BitTorrent enhancement proposals):

• BEP#0003: The BitTorrent protocol specification (complete) This is the base official protocol specification, which Ttorrent implements fully.
• BEP#0007: IPv6 Tracker Extension
• BEP#0010: Extension Protocol
• BEP#0012: Multi-tracker metadata extension
  Full support for the announce-list meta-info key providing a tiered tracker list.
• BEP#0015: UDP Tracker Protocol for BitTorrent (partial) The UDP tracker protocol is fully supported in the BitTorrent client to make announce requests to UDP trackers. UDP tracker support itself is planned.
• BEP#0020: Peer ID conventions
  Ttorrent uses TO as the client identification string, and currently uses the -T00042- client ID prefix.
• BEP#0023: Tracker Returns Compact Peer Lists
  Compact peer lists are supported in both the client and the tracker. Currently the tracker only supports sending back compact peer lists to an announce request.
• BEP#0024: Tracker Returns External IP

In addition, the following extensions are supported:

• Peer Exchange (ut_pex) with PEX seeding for fast trackerless operation.
• Linux epoll() (See ClientEnvironment#setEventLoopType()).

History

This tool suite was implemented as part of Turn's (http://www.turn.com) release distribution and deployment system and is used to distribute new build tarballs to a large number of machines inside a datacenter as efficiently as possible. At the time this project was started, few Java implementations of the BitTorrent protocol existed and unfortunately none of them fit our needs:

• Vuze's, which is very hard to extract from their codebase, and thus complex to re-integrate into another application;
• torrent4j, which is largely incomplete and not usable;
• Snark's, which is old, and unfortunately unstable;
• bitext, which was also unfortunately unstable, and extremely slow.

The APIs and implementation were thoroughly overhauled in this fork, with the objective of sharing a multi-gigabyte file to a thousand hosts in a matter of seconds.

How to use

As standalone programs

The client, tracker and torrent file manipulation utilities will all present a usage message on the console when invoked with the -h command-line flag.

As a library

To use ttorrent is a library in your project, all you need is to declare the dependency on the latest version of ttorrent. For example, if you use Maven, add the following in your POM's dependencies section:

  <dependencies>
    ...
    <dependency>
      <groupId>org.anarres.ttorrent</groupId>
      <artifactId>ttorrent-client</groupId>
      <version>1.8.0-SNAPSHOT</version>
    </dependency>
  </dependencies>

Client code

// First, instantiate the Client object.
Client client = new Client();

// Configure the client as desired.
client.getEnvironment.set*();

// Add one or more torrents.
Torrent torrent = new Torrent(new File("/path/to/your.torrent"))
client.addTorrent(torrent, new File("/path/to/output/directory"));

client.start();

At any time you can call client.stop() to interrupt the download. You can also add a ClientListener to wait for a download to complete.

Tracker code

For a tracker, there are a number of options:

Standalone:

SimpleTracker tracker = new SimpleTracker(new InetSocketAddress(6969));
tracker.addTorrent(new Torrent("/path/to/file"));
tracker.start();

// You can stop the tracker when you're done with:
tracker.stop();

Servlets/Jetty: See TrackerServlet.

Spring Framework: See TrackerController.

JavaDoc API

The JavaDoc API is available.

License

This BitTorrent library is distributed under the terms of the Apache Software License version 2.0. See COPYING file for more details.

Authors and contributors

• Maxime Petazzoni <maxime.petazzoni@bulix.org> (Software Engineer at SignalFuse, Inc)
  Original author, main developer and maintainer
• David Giffin <david@etsy.com>
  Contributed parallel hashing and multi-file torrent support.
• Thomas Zink <thomas.zink@uni-konstanz.de>
  Fixed a piece length computation issue when the total torrent size is an exact multiple of the piece size.
• Johan Parent <<parent_johan@yahoo.com>>
  Fixed a bug in unfresh peer collection and issues on download completion on Windows platforms.
• Dmitriy Dumanskiy
  Contributed the switch from Ant to Maven.
• Alexey Ptashniy
  Fixed an integer overflow in the calculation of a torrent's full size.

Caveats

Contributions are welcome in all areas, even more so for these few points above!