135 lines
5.0 KiB
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135 lines
5.0 KiB
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=================
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libtorrent manual
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=================
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:Author: Arvid Norberg, arvid@rasterbar.com
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.. contents:: Table of contents
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:depth: 2
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:backlinks: none
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introduction
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============
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libtorrent is a C++ library that aims to be a good alternative to all the
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other bittorrent implementations around. It is a
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library and not a full featured client, although it comes with a working
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example client.
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The main goals of libtorrent are:
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* to be cpu efficient
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* to be memory efficient
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* to be very easy to use
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features
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========
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libtorrent is still being developed, however it is stable. It is an ongoing
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project (including this documentation). The current state includes the
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following features:
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* trackerless torrents (using the Mainline kademlia DHT protocol) with
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some `DHT extensions`_.
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* support for IPv6
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* NAT-PMP and UPnP support (automatic port mapping on routers that supports it)
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* uses a separate disk I/O thread to not have the disk ever block on network or
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client interaction. (see threads_).
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* supports the bittorrent `extension protocol`_. See extensions_.
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* supports the uTorrent metadata transfer protocol (i.e. magnet links).
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* supports the uTorrent peer exchange protocol (PEX).
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* supports local peer discovery (multicasts for peers on the same local network)
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* adjusts the length of the request queue depending on download rate.
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* has an adjustable read and write disk cache for improved disk throughput.
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* multitracker extension support (supports both the `specification by John Hoffman`__
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and the uTorrent interpretation).
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* tracker scrapes
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* supports both sparse files and compact file allocation (where pieces
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are kept consolidated on disk)
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* supports files > 2 gigabytes.
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* serves multiple torrents on a single port and in a single thread
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* fast resume support, a way to get rid of the costly piece check at the
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start of a resumed torrent. Saves the storage state, piece_picker state
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as well as all local peers in a separate fast-resume file.
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* `HTTP seeding`_, as `specified by Michael Burford of GetRight`__.
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* piece picking on block-level (as opposed to piece-level).
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This means it can download parts of the same piece from different peers.
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It will also prefer to download whole pieces from single peers if the
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download speed is high enough from that particular peer.
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* supports the `udp-tracker protocol`_ by Olaf van der Spek.
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* queues torrents for file check, instead of checking all of them in parallel.
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* supports http proxies and basic proxy authentication
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* gzipped tracker-responses
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* can limit the upload and download bandwidth usage and the maximum number of
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unchoked peers
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* implements fair trade. User settable trade-ratio, must at least be 1:1,
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but one can choose to trade 1 for 2 or any other ratio that isn't unfair
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to the other party.
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* supports the ``no_peer_id=1`` extension that will ease the load off trackers.
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* possibility to limit the number of connections.
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* delays have messages if there's no other outgoing traffic to the peer, and
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doesn't send have messages to peers that already has the piece. This saves
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bandwidth.
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* does not have any requirements on the piece order in a torrent that it
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resumes. This means it can resume a torrent downloaded by any client.
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* supports the ``compact=1`` tracker parameter.
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* selective downloading. The ability to select which parts of a torrent you
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want to download.
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* ip filter to disallow ip addresses and ip ranges from connecting and
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being connected
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.. _`DHT extensions`: dht_extensions.html
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__ http://home.elp.rr.com/tur/multitracker-spec.txt
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__ http://www.getright.com/seedtorrent.html
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.. _`extension protocol`: extension_protocol.html
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.. _`udp-tracker protocol`: udp_tracker_protocol.html
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portability
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===========
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libtorrent is portable at least among Windows, MacOS X and other UNIX-systems.
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It uses Boost.Thread, Boost.Filesystem, Boost.Date_time and various other
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boost libraries as well as zlib_ (shipped) and asio_ (shipped). At least version
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1.33.1 of boost is required.
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.. _zlib: http://www.zlib.org
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.. _asio: http://asio.sf.net
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Since libtorrent uses asio, it will take full advantage of high performance
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network APIs on the most popular platforms. I/O completion ports on windows,
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epoll on linux and kqueue on MacOS X and BSD.
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libtorrent has been successfully compiled and tested on:
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* Windows 2000 vc7.1, vc8
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* Linux x86 GCC 3.3, GCC 3.4.2
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* MacOS X (darwin), (Apple's) GCC 3.3, (Apple's) GCC 4.0
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* SunOS 5.8 GCC 3.1
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* Cygwin GCC 3.3.3
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Fails on:
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* GCC 2.95.4
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* msvc6
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license
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=======
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libtorrent is released under the BSD-license_.
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.. _BSD-license: http://www.opensource.org/licenses/bsd-license.php
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This means that you can use the library in your project without having to
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release its source code. The only requirement is that you give credit
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to the author of the library by including the libtorrent license in your
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software or documentation.
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`Here's`__ a list of some projects that uses libtorrent.
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__ projects.html
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.. _`http seeding`: manual.html#http-seeding
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.. _threads: manual.html#threads
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.. _extensions: manual.html#extensions
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