forked from premiere/premiere-libtorrent
870 lines
45 KiB
HTML
Executable File
870 lines
45 KiB
HTML
Executable File
<?xml version="1.0" encoding="utf-8" ?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="generator" content="Docutils 0.3.1: http://docutils.sourceforge.net/" />
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<title>libtorrent</title>
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<link rel="stylesheet" href="style.css" type="text/css" />
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</head>
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<body>
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<div class="document" id="libtorrent">
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<h1 class="title">libtorrent</h1>
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<table border class="table">
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<colgroup>
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<col width="56%" />
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<col width="44%" />
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</colgroup>
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<tbody valign="top">
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<tr><td><a class="reference" href="http://www.sourceforge.net/projects/libtorrent">sourceforge page</a></td>
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<td><a class="reference" href="http://lists.sourceforge.net/lists/listinfo/libtorrent-discus">mailing list</a></td>
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</tr>
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</tbody>
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</table>
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<div class="contents topic" id="contents">
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<p class="topic-title"><a name="contents">Contents</a></p>
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<ul class="simple">
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<li><a class="reference" href="#introduction" id="id6" name="id6">introduction</a></li>
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<li><a class="reference" href="#building" id="id7" name="id7">building</a></li>
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<li><a class="reference" href="#using" id="id8" name="id8">using</a><ul>
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<li><a class="reference" href="#session" id="id9" name="id9">session</a></li>
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<li><a class="reference" href="#parsing-torrent-files" id="id10" name="id10">parsing torrent files</a></li>
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<li><a class="reference" href="#entry" id="id11" name="id11">entry</a></li>
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<li><a class="reference" href="#torrent-info" id="id12" name="id12">torrent_info</a></li>
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<li><a class="reference" href="#torrent-handle" id="id13" name="id13">torrent_handle</a><ul>
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<li><a class="reference" href="#status" id="id14" name="id14">status()</a></li>
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<li><a class="reference" href="#get-download-queue" id="id15" name="id15">get_download_queue()</a></li>
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<li><a class="reference" href="#get-peer-info" id="id16" name="id16">get_peer_info()</a></li>
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<li><a class="reference" href="#get-torrent-info" id="id17" name="id17">get_torrent_info()</a></li>
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<li><a class="reference" href="#is-valid" id="id18" name="id18">is_valid()</a></li>
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</ul>
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</li>
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<li><a class="reference" href="#address" id="id19" name="id19">address</a></li>
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<li><a class="reference" href="#http-settings" id="id20" name="id20">http_settings</a></li>
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<li><a class="reference" href="#big-number" id="id21" name="id21">big_number</a></li>
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<li><a class="reference" href="#hasher" id="id22" name="id22">hasher</a></li>
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<li><a class="reference" href="#exceptions" id="id23" name="id23">exceptions</a><ul>
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<li><a class="reference" href="#invalid-handle" id="id24" name="id24">invalid_handle</a></li>
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<li><a class="reference" href="#duplicate-torrent" id="id25" name="id25">duplicate_torrent</a></li>
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<li><a class="reference" href="#invalid-encoding" id="id26" name="id26">invalid_encoding</a></li>
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<li><a class="reference" href="#type-error" id="id27" name="id27">type_error</a></li>
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<li><a class="reference" href="#invalid-torrent-file" id="id28" name="id28">invalid_torrent_file</a></li>
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</ul>
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</li>
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<li><a class="reference" href="#example-usage" id="id29" name="id29">example usage</a><ul>
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<li><a class="reference" href="#dump-torrent" id="id30" name="id30">dump_torrent</a></li>
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<li><a class="reference" href="#simple-client" id="id31" name="id31">simple client</a></li>
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</ul>
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</li>
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</ul>
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</li>
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<li><a class="reference" href="#feedback" id="id32" name="id32">Feedback</a></li>
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<li><a class="reference" href="#aknowledgements" id="id33" name="id33">Aknowledgements</a></li>
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</ul>
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</div>
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<div class="section" id="introduction">
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<h1><a class="toc-backref" href="#id6" name="introduction">introduction</a></h1>
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<p>libtorrent is a C++ library that aims to be a good alternative to all the
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<a class="reference" href="links.html">other bittorrent implementations</a> 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.</p>
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<p>The main goals of libtorrent are:</p>
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<blockquote>
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<ul class="simple">
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<li>to be cpu efficient</li>
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<li>to be memory efficient</li>
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<li>to be very easy to use</li>
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</ul>
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</blockquote>
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<p>libtorrent is not finished. It is an ongoing project (including this documentation).
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The current state includes the following features:</p>
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<blockquote>
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<ul class="simple">
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<li>multitracker extension support (as <a class="reference" href="http://home.elp.rr.com/tur/multitracker-spec.txt">described by TheShadow</a>)</li>
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<li>serves multiple torrents on a single port and a single thread</li>
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<li>supports http proxies and proxy authentication</li>
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<li>gzipped tracker-responses</li>
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<li>piece picking on block-level (as opposed to piece-level) like in <a class="reference" href="http://azureus.sourceforge.net">Azureus</a></li>
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<li>queues torrents for file check, instead of checking all of them in parallel.</li>
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<li>uses separate threads for checking files and for main downloader, with a fool-proof
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thread-safe library interface. (i.e. There's no way for the user to cause a deadlock).</li>
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<li>can limit the upload bandwidth usage</li>
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<li>piece-wise file allocation</li>
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</ul>
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</blockquote>
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<p>Functions that are yet to be implemented:</p>
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<blockquote>
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<ul class="simple">
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<li>optimistic unchoke</li>
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<li>choke/unchoke algorithm</li>
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<li>Snubbing</li>
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<li>fast resume</li>
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<li>file-level piece priority</li>
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<li>a good upload speed cap (the one currently used don't balance loads between peers)</li>
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</ul>
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</blockquote>
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<p>libtorrent is portable at least among windows, macosx, and UNIX-systems. It uses boost.thread,
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boost.filesystem boost.date_time and various other boost libraries and zlib.</p>
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<p>libtorrent has been successfully compiled and tested on:</p>
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<blockquote>
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<ul class="simple">
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<li>Cygwin GCC 3.3.1</li>
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<li>Windows 2000 vc7.1</li>
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<li>Linux x86 (debian) GCC 3.0</li>
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</ul>
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</blockquote>
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</div>
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<div class="section" id="building">
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<h1><a class="toc-backref" href="#id7" name="building">building</a></h1>
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<p>To build libtorrent you need <a class="reference" href="http://www.boost.org">boost</a> and bjam installed.
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Then you can use <tt class="literal"><span class="pre">bjam</span></tt> to build libtorrent.</p>
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<p>To make bjam work, you need to set the environment variable <tt class="literal"><span class="pre">BOOST_ROOT</span></tt> to the
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path where boost is installed (e.g. c:boost_1_30_2 on windows). Then you can just run
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<tt class="literal"><span class="pre">bjam</span></tt> in the libtorrent directory.</p>
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<p>The Jamfile doesn't work yet. On unix-systems you can use the makefile however. You
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first have to build boost.thread and boost.filesystem. You do this by, in the directory
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'boost-1.30.2/tools/build/jam_src' run the build script <tt class="literal"><span class="pre">./build.sh</span></tt>. This should
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produce at least one folder with the 'bin' prefix (and the rest of the name describes
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your platform). Put the files in that folder somewhere in your path.</p>
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<p>You can then invoke <tt class="literal"><span class="pre">bjam</span></tt> in the directories 'boost-1.30.2/libs/thread/build' and
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'boost-1.30.2/libs/filesystem/build'. That will produce the needed libraries. Put these
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libraries in the libtorrent root directory. You then have to modify the makefile to use
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you prefered compiler and to have the correct path to your boost istallation.</p>
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<p>Then the makefile should be able to do the rest.</p>
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<p>When building (with boost 1.30.2) on linux and solaris however, I found that I had to make the following
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modifications to the boost.date-time library. In the file:
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'boost-1.30.2/boost/date_time/gregorian_calendar.hpp' line 59. Prepend 'boost/date_time/'
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to the include path.</p>
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<p>And the second modification was in the file:
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'boost-1.30.2/boost/date_time/microsec_time_clock.hpp' add the following include at the top
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of the file:</p>
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<pre class="literal-block">
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#include "boost/cstdint.hpp"
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</pre>
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<p>In developer studio, you may have to set the compiler options "force conformance in for
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loop scope" and "treat wchar_t as built-in type" to Yes.</p>
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<p>TODO: more detailed build instructions.</p>
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</div>
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<div class="section" id="using">
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<h1><a class="toc-backref" href="#id8" name="using">using</a></h1>
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<p>The interface of libtorrent consists of a few classes. The main class is
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the <tt class="literal"><span class="pre">session</span></tt>, it contains the main loop that serves all torrents.</p>
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<div class="section" id="session">
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<h2><a class="toc-backref" href="#id9" name="session">session</a></h2>
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<p>The <tt class="literal"><span class="pre">session</span></tt> class has the following synopsis:</p>
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<pre class="literal-block">
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class session: public boost::noncopyable
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{
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session(int listen_port, const std::string& fingerprint = std::string());
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torrent_handle add_torrent(const torrent_info& t, const std::string& save_path);
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void remove_torrent(const torrent_handle& h);
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void set_http_settings(const http_settings& settings);
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void set_upload_rate_limit(int bytes_per_second);
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};
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</pre>
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<p>Once it's created, it will spawn the main thread that will do all the work.
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The main thread will be idle as long it doesn't have any torrents to participate in.
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You add torrents through the <tt class="literal"><span class="pre">add_torrent()</span></tt>-function where you give an
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object representing the information found in the torrent file and the path where you
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want to save the files. The <tt class="literal"><span class="pre">save_path</span></tt> will be prepended to the directory-
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structure in the torrent-file. <tt class="literal"><span class="pre">add_torrent</span></tt> will throw <tt class="literal"><span class="pre">duplicate_torrent</span></tt> exception
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if the torrent already exists in the session.</p>
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<p><tt class="literal"><span class="pre">remove_torrent()</span></tt> will close all peer connections associated with the torrent and tell
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the tracker that we've stopped participating in the swarm.</p>
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<p>If the torrent you are trying to add already exists in the session (is either queued
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for checking, being checked or downloading) <tt class="literal"><span class="pre">add_torrent()</span></tt> will throw
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<tt class="literal"><span class="pre">duplicate_torrent</span></tt> which derives from <tt class="literal"><span class="pre">std::exception</span></tt>.</p>
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<p><tt class="literal"><span class="pre">fingerprint</span></tt> is a short string that will be used in the peer_id to
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identify the client. If the string is longer than 7 characters it will
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be trimmed down to 7 characters. The default is an empty string.</p>
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<p><tt class="literal"><span class="pre">set_upload_rate_limit()</span></tt> set the maximum number of bytes allowed to be
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sent to peers per second. This bandwidth is distributed among all the peers. If
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you don't want to limit upload rate, you can set this to -1 (the default).</p>
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<p>The destructor of session will notify all trackers that our torrents has been shut down.
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If some trackers are down, they will timout. All this before the destructor of session
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returns. So, it's adviced that any kind of interface (such as windows) are closed before
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destructing the sessoin object. Because it can take a few second for it to finish. The
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timeout can be set with <tt class="literal"><span class="pre">set_http_settings()</span></tt>.</p>
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<p>How to parse a torrent file and create a <tt class="literal"><span class="pre">torrent_info</span></tt> object is described below.</p>
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<p>The <a class="reference" href="#torrent-handle">torrent_handle</a> returned by <tt class="literal"><span class="pre">add_torrent</span></tt> can be used to retrieve information
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about the torrent's progress, its peers etc. It is also used to abort a torrent.</p>
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<p>The constructor takes a listen port as argument, if the given port is busy it will
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increase the port number by one and try again. If it still fails it will continue
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increasing the port number until it succeeds or has failed 9 ports. <em>This will
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change in the future to give more control of the listen-port.</em></p>
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</div>
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<div class="section" id="parsing-torrent-files">
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<h2><a class="toc-backref" href="#id10" name="parsing-torrent-files">parsing torrent files</a></h2>
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<p>The torrent files are <a class="reference" href="http://bitconjurer.org/BitTorrent/protocol.html">bencoded</a>. There are two functions in libtorrent that can encode and decode
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bencoded data. They are:</p>
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<pre class="literal-block">
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template<class InIt> entry bdecode(InIt start, InIt end);
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template<class OutIt> void bencode(OutIt out, const entry& e);
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</pre>
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<p>The <tt class="literal"><span class="pre">entry</span></tt> class is the internal representation of the bencoded data
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and it can be used to retreive information, an entry can also be build by
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the program and given to <tt class="literal"><span class="pre">bencode()</span></tt> to encode it into the <tt class="literal"><span class="pre">OutIt</span></tt>
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iterator.</p>
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<p>The <tt class="literal"><span class="pre">OutIt</span></tt> and <tt class="literal"><span class="pre">InIt</span></tt> are iterators
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(<tt class="literal"><span class="pre">InputIterator_</span></tt> and <tt class="literal"><span class="pre">OutputIterator_</span></tt> respectively). They
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are templates and are usually instantiated as <tt class="literal"><span class="pre">ostream_iterator_</span></tt>,
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<tt class="literal"><span class="pre">back_insert_iterator_</span></tt> or <tt class="literal"><span class="pre">istream_iterator_</span></tt>. These
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functions will assume that the iterator refers to a character
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(<tt class="literal"><span class="pre">char</span></tt>). So, if you want to encode entry <tt class="literal"><span class="pre">e</span></tt> into a buffer
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in memory, you can do it like this:</p>
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<pre class="literal-block">
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std::vector<char> buffer;
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bencode(std::back_insert_iterator<std::vector<char> >(buf), e);
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</pre>
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<p>If you want to decode a torrent file from a buffer in memory, you can do it like this:</p>
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<pre class="literal-block">
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std::vector<char> buffer;
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// ...
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entry e = bdecode(buf.begin(), buf.end());
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</pre>
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<p>Or, if you have a raw char buffer:</p>
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<pre class="literal-block">
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const char* buf;
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// ...
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entry e = bdecode(buf, buf + data_size);
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</pre>
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<p>Now we just need to know how to retrieve information from the <tt class="literal"><span class="pre">entry</span></tt>.</p>
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</div>
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<div class="section" id="entry">
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<h2><a class="toc-backref" href="#id11" name="entry">entry</a></h2>
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<p>The <tt class="literal"><span class="pre">entry</span></tt> class represents one node in a bencoded hierarchy. It works as a
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variant type, it can be either a list, a dictionary (<tt class="literal"><span class="pre">std::map</span></tt>), an integer
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or a string. This is its synopsis:</p>
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<pre class="literal-block">
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class entry
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{
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public:
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typedef std::map<std::string, entry> dictionary_type;
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typedef std::string string_type;
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typedef std::vector<entry> list_type;
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typedef implementation-defined integer_type;
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enum data_type
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{
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int_t,
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string_t,
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list_t,
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dictionary_t,
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undefined_t
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};
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data_type type() const;
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entry();
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entry(data_type t);
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entry(const entry& e);
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void operator=(const entry& e);
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integer_type& integer()
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const integer_type& integer() const;
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string_type& string();
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const string_type& string() const;
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list_type& list();
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const list_type& list() const;
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dictionary_type& dict();
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const dictionary_type& dict() const;
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void print(std::ostream& os, int indent = 0) const;
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};
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</pre>
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<p>The <tt class="literal"><span class="pre">integer()</span></tt>, <tt class="literal"><span class="pre">string()</span></tt>, <tt class="literal"><span class="pre">list()</span></tt> and <tt class="literal"><span class="pre">dict()</span></tt> functions
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are accessorts that return the respecive type. If the <tt class="literal"><span class="pre">entry</span></tt> object isn't of the
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type you request, the accessor will throw <tt class="literal"><span class="pre">type_error</span></tt> (which derives from
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<tt class="literal"><span class="pre">std::runtime_error</span></tt>). You can ask an <tt class="literal"><span class="pre">entry</span></tt> for its type through the
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<tt class="literal"><span class="pre">type()</span></tt> function.</p>
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<p>The <tt class="literal"><span class="pre">print()</span></tt> function is there for debug purposes only.</p>
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<p>If you want to create an <tt class="literal"><span class="pre">entry</span></tt> you give it the type you want it to have in its
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constructor, and then use one of the non-const accessors to get a reference which you then
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can assign the value you want it to have.</p>
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<p>The typical code to get info from a torrent file will then look like this:</p>
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<pre class="literal-block">
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entry torrent_file;
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// ...
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const entry::dictionary_type& dict = torrent_file.dict();
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entry::dictionary_type::const_iterator i;
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i = dict.find("announce");
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if (i != dict.end())
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{
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std::string tracker_url= i->second.string();
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std::cout << tracker_url << "\n";
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}
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</pre>
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<p>To make it easier to extract information from a torren file, the class <tt class="literal"><span class="pre">torrent_info</span></tt>
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exists.</p>
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</div>
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<div class="section" id="torrent-info">
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<h2><a class="toc-backref" href="#id12" name="torrent-info">torrent_info</a></h2>
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<p>The <tt class="literal"><span class="pre">torrent_info</span></tt> has the following synopsis:</p>
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<pre class="literal-block">
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class torrent_info
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{
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public:
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torrent_info(const entry& torrent_file)
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typedef std::vector>file>::const_iterator file_iterator;
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typedef std::vector<file>::const_reverse_iterator reverse_file_iterator;
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file_iterator begin_files() const;
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file_iterator end_files() const;
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reverse_file_iterator rbegin_files() const;
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reverse_file_iterator rend_files() const;
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std::size_t num_files() const;
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const file& file_at(int index) const;
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const std::vector<announce_entry>& trackers() const;
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int prioritize_tracker(int index);
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entry::integer_type total_size() const;
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entry::integer_type piece_length() const;
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std::size_t num_pieces() const;
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const sha1_hash& info_hash() const;
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const std::stirng& name() const;
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const std::string& comment() const;
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boost::posiz_time::ptime creation_date() const;
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void print(std::ostream& os) const;
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entry::integer_type piece_size(unsigned int index) const;
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const sha1_hash& hash_for_piece(unsigned int index) const;
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};
|
|
</pre>
|
|
<p>This class will need some explanation. First of all, to get a list of all files
|
|
in the torrent, you can use <tt class="literal"><span class="pre">begin_files()</span></tt>, <tt class="literal"><span class="pre">end_files()</span></tt>,
|
|
<tt class="literal"><span class="pre">rbegin_files()</span></tt> and <tt class="literal"><span class="pre">rend_files()</span></tt>. These will give you standard vector
|
|
iterators with the type <tt class="literal"><span class="pre">file</span></tt>.</p>
|
|
<pre class="literal-block">
|
|
struct file
|
|
{
|
|
std::string path;
|
|
std::string filename;
|
|
entry::integer_type size;
|
|
};
|
|
</pre>
|
|
<p>If you need index-access to files you can use the <tt class="literal"><span class="pre">num_files()</span></tt> and <tt class="literal"><span class="pre">file_at()</span></tt>
|
|
to access files using indices.</p>
|
|
<p>The <tt class="literal"><span class="pre">print()</span></tt> function is there for debug purposes only. It will print the info from
|
|
the torrent file to the given outstream.</p>
|
|
<p><tt class="literal"><span class="pre">name()</span></tt> returns the name of the torrent.</p>
|
|
<p>The <tt class="literal"><span class="pre">trackers()</span></tt> function will return a sorted vector of <tt class="literal"><span class="pre">announce_entry</span></tt>.
|
|
Each announce entry contains a string, which is the tracker url, and a tier index. The
|
|
tier index is the high-level priority. No matter which trackers that works or not, the
|
|
ones with lower tier will always be tried before the one with higher tier number.</p>
|
|
<pre class="literal-block">
|
|
struct announce_entry
|
|
{
|
|
std::string url;
|
|
int tier;
|
|
};
|
|
</pre>
|
|
<p>The <tt class="literal"><span class="pre">prioritize_tracker()</span></tt> is used internally to move a tracker to the front
|
|
of its tier group. i.e. It will never be moved pass a tracker with a different tier
|
|
number. For more information about how multiple trackers are dealt with, see the
|
|
<a class="reference" href="http://home.elp.rr.com/tur/multitracker-spec.txt">specification</a>.</p>
|
|
<p><tt class="literal"><span class="pre">total_size()</span></tt>, <tt class="literal"><span class="pre">piece_length()</span></tt> and <tt class="literal"><span class="pre">num_pieces()</span></tt> returns the total
|
|
number of bytes the torrent-file represents (all the files in it), the number of byte for
|
|
each piece and the total number of pieces, respectively. The difference between
|
|
<tt class="literal"><span class="pre">piece_size()</span></tt> and <tt class="literal"><span class="pre">piece_length()</span></tt> is that <tt class="literal"><span class="pre">piece_size()</span></tt> takes
|
|
the piece index as argument and gives you the exact size of that piece. It will always
|
|
be the same as <tt class="literal"><span class="pre">piece_length()</span></tt> except in the case of the last piece, which may
|
|
be smaller.</p>
|
|
<p><tt class="literal"><span class="pre">hash_for_piece()</span></tt> takes a piece-index and returns the 20-bytes sha1-hash for that
|
|
piece and <tt class="literal"><span class="pre">info_hash()</span></tt> returns the 20-bytes sha1-hash for the info-section of the
|
|
torrent file. For more information on the <tt class="literal"><span class="pre">sha1_hash</span></tt>, see the <a class="reference" href="#big-number">big_number</a> class.</p>
|
|
<p><tt class="literal"><span class="pre">comment()</span></tt> returns the comment associated with the torrent. If there's no comment,
|
|
it will return an empty string. <tt class="literal"><span class="pre">creation_date()</span></tt> returns a <tt class="literal"><span class="pre">boost::posix_time::ptime_</span></tt>
|
|
object, representing the time when this torrent file was created. If there's no timestamp
|
|
in the torrent file, this will return a date of january 1:st 1970.</p>
|
|
</div>
|
|
<div class="section" id="torrent-handle">
|
|
<h2><a class="toc-backref" href="#id13" name="torrent-handle">torrent_handle</a></h2>
|
|
<p>You will usually have to store your torrent handles somewhere, since it's the
|
|
object through which you retrieve infromation about the torrent and aborts the torrent.
|
|
Its declaration looks like this:</p>
|
|
<pre class="literal-block">
|
|
struct torrent_handle
|
|
{
|
|
torrent_handle();
|
|
|
|
torrent_status status();
|
|
void get_download_queue(std::vector<partial_piece_info>& queue);
|
|
void get_peer_info(std::vector<peer_info>& v);
|
|
const torrent_info& get_torrent_info();
|
|
bool is_valid();
|
|
};
|
|
</pre>
|
|
<p>The default constructor will initialize the handle to an invalid state. Which means you cannot
|
|
perform any operation on it, unless you first assign it a valid handle. If you try to perform
|
|
any operation they will simply return.</p>
|
|
<div class="section" id="status">
|
|
<h3><a class="toc-backref" href="#id14" name="status">status()</a></h3>
|
|
<p><tt class="literal"><span class="pre">status()</span></tt> will return a structure with information about the status of this
|
|
torrent. If the <tt class="literal"><span class="pre">torrent_handle</span></tt> is invalid, it will throw <tt class="literal"><span class="pre">invalid_handle</span></tt> exception.
|
|
It contains the following fields:</p>
|
|
<pre class="literal-block">
|
|
struct torrent_status
|
|
{
|
|
enum state_t
|
|
{
|
|
invalid_handle,
|
|
queued_for_checking,
|
|
checking_files,
|
|
downloading,
|
|
seeding
|
|
};
|
|
|
|
state_t state;
|
|
float progress;
|
|
boost::posix_time::time_duration next_announce;
|
|
std::size_t total_download;
|
|
std::size_t total_upload;
|
|
std::vector<bool> pieces;
|
|
std::size_t total_done;
|
|
};
|
|
</pre>
|
|
<p><tt class="literal"><span class="pre">progress</span></tt> is a value in the range [0, 1], that represents the progress of the
|
|
torrent's current task. It may be checking files or downloading. The torrent's
|
|
current task is in the <tt class="literal"><span class="pre">state</span></tt> member, it will be one of the following:</p>
|
|
<table border class="table">
|
|
<colgroup>
|
|
<col width="28%" />
|
|
<col width="72%" />
|
|
</colgroup>
|
|
<tbody valign="top">
|
|
<tr><td><tt class="literal"><span class="pre">queued_for_checking</span></tt></td>
|
|
<td>The torrent is in the queue for being checked. But there
|
|
currently is another torrent that are being checked.
|
|
This torrent will wait for its turn.</td>
|
|
</tr>
|
|
<tr><td><tt class="literal"><span class="pre">checking_files</span></tt></td>
|
|
<td>The torrent has not started its download yet, and is
|
|
currently checking existing files.</td>
|
|
</tr>
|
|
<tr><td><tt class="literal"><span class="pre">downloading</span></tt></td>
|
|
<td>The torrent is being downloaded. This is the state
|
|
most torrents will be in most of the time. The progress
|
|
meter will tell how much of the files that has been
|
|
downloaded.</td>
|
|
</tr>
|
|
<tr><td><tt class="literal"><span class="pre">seeding</span></tt></td>
|
|
<td>In this state the torrent has finished downloading and
|
|
is a pure seeder.</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p><tt class="literal"><span class="pre">next_announce</span></tt> is the time until the torrent will announce itself to the tracker.</p>
|
|
<p><tt class="literal"><span class="pre">total_download</span></tt> and <tt class="literal"><span class="pre">total_upload</span></tt> is the number of bytes downloaded and
|
|
uploaded to all peers, accumulated, <em>this session</em> only.</p>
|
|
<p><tt class="literal"><span class="pre">pieces</span></tt> is the bitmask that representw which pieces we have (set to true) and
|
|
the pieces we don't have.</p>
|
|
<p><tt class="literal"><span class="pre">total_done</span></tt> is the total number of bytes of the file(s) that we have.</p>
|
|
</div>
|
|
<div class="section" id="get-download-queue">
|
|
<h3><a class="toc-backref" href="#id15" name="get-download-queue">get_download_queue()</a></h3>
|
|
<p><tt class="literal"><span class="pre">get_download_queue()</span></tt> takes a non-const reference to a vector which it will fill
|
|
information about pieces that are partially downloaded or not downloaded at all but partially
|
|
requested. The entry in the vector (<tt class="literal"><span class="pre">partial_piece_info</span></tt>) looks like this:</p>
|
|
<pre class="literal-block">
|
|
struct partial_piece_info
|
|
{
|
|
enum { max_blocks_per_piece };
|
|
int piece_index;
|
|
int blocks_in_piece;
|
|
std::bitset<max_blocks_per_piece> requested_blocks;
|
|
std::bitset<max_blocks_per_piece> finished_blocks;
|
|
peer_id peer[max_blocks_per_piece];
|
|
int num_downloads[max_blocks_per_piece];
|
|
};
|
|
</pre>
|
|
<p><tt class="literal"><span class="pre">piece_index</span></tt> is the index of the piece in question. <tt class="literal"><span class="pre">blocks_in_piece</span></tt> is the
|
|
number of blocks in this particular piece. This number will be the same for most pieces, but
|
|
the last piece may have fewer blocks than the standard pieces.</p>
|
|
<p><tt class="literal"><span class="pre">requested_blocks</span></tt> is a bitset with one bit per block in the piece. If a bit is set, it
|
|
means that that block has been requested, but not necessarily fully downloaded yet. To know
|
|
from whom the block has been requested, have a look in the <tt class="literal"><span class="pre">peer</span></tt> array. The bit-index
|
|
in the <tt class="literal"><span class="pre">requested_blocks</span></tt> and <tt class="literal"><span class="pre">finished_blocks</span></tt> correspons to the array-index into
|
|
<tt class="literal"><span class="pre">peers</span></tt> and <tt class="literal"><span class="pre">num_downloads</span></tt>. The array of peers is contains the id of the
|
|
peer the piece was requested from. If a piece hasn't been requested (the bit in
|
|
<tt class="literal"><span class="pre">requested_blocks</span></tt> is not set) the peer array entry will be undefined.</p>
|
|
<p>The <tt class="literal"><span class="pre">finished_blocks</span></tt> is a bitset where each bit says if the block is fully downloaded
|
|
or not. And the <tt class="literal"><span class="pre">num_downloads</span></tt> array says how many times that block has been downloaded.
|
|
When a piece fails a hash verification, single blocks may be redownloaded to see if the hash teast
|
|
may pass then.</p>
|
|
</div>
|
|
<div class="section" id="get-peer-info">
|
|
<h3><a class="toc-backref" href="#id16" name="get-peer-info">get_peer_info()</a></h3>
|
|
<p><tt class="literal"><span class="pre">get_peer_info()</span></tt> takes a reference to a vector that will be cleared and filled
|
|
with one entry for each peer connected to this torrent, given the handle is valid. If the
|
|
<tt class="literal"><span class="pre">torrent_handle</span></tt> is invalid, it will throw <tt class="literal"><span class="pre">invalid_handle</span></tt> exception. Each entry in
|
|
the vector contains information about that particular peer. It contains the following
|
|
fields:</p>
|
|
<pre class="literal-block">
|
|
struct peer_info
|
|
{
|
|
enum
|
|
{
|
|
interesting = 0x1,
|
|
choked = 0x2,
|
|
remote_interested = 0x4,
|
|
remote_choked = 0x8
|
|
};
|
|
unsigned int flags;
|
|
address ip;
|
|
float up_speed;
|
|
float down_speed;
|
|
unsigned int total_download;
|
|
unsigned int total_upload;
|
|
peer_id id;
|
|
std::vector<bool> pieces;
|
|
int upload_limit;
|
|
};
|
|
</pre>
|
|
<p>The <tt class="literal"><span class="pre">flags</span></tt> attribute tells you in which state the peer is. It is set to
|
|
any combination of the four enums above. Where <tt class="literal"><span class="pre">interesting</span></tt> means that we
|
|
are interested in pieces from this peer. <tt class="literal"><span class="pre">choked</span></tt> means that <strong>we</strong> have
|
|
choked this peer. <tt class="literal"><span class="pre">remote_interested</span></tt> and <tt class="literal"><span class="pre">remote_choked</span></tt> means the
|
|
same thing but that the peer is interested in pieces from us and the peer has choked
|
|
<strong>us</strong>.</p>
|
|
<p>The <tt class="literal"><span class="pre">ip</span></tt> field is the IP-address to this peer. Its type is a wrapper around the
|
|
actual address and the port number. See <a class="reference" href="#address">address</a> class.</p>
|
|
<p><tt class="literal"><span class="pre">up_speed</span></tt> and <tt class="literal"><span class="pre">down_speed</span></tt> is the current upload and download speed
|
|
we have to and from this peer. These figures are updated aproximately once every second.</p>
|
|
<p><tt class="literal"><span class="pre">total_download</span></tt> and <tt class="literal"><span class="pre">total_upload</span></tt> are the total number of bytes downloaded
|
|
from and uploaded to this peer. These numbers do not include the protocol chatter, but only
|
|
the payload data.</p>
|
|
<p><tt class="literal"><span class="pre">id</span></tt> is the peer's id as used in the bit torrent protocol. This id can be used to
|
|
extract 'fingerprints' from the peer. Sometimes it can tell you which client the peer
|
|
is using.</p>
|
|
<p><tt class="literal"><span class="pre">pieces</span></tt> is a vector of booleans that has as many entries as there are pieces
|
|
in the torrent. Each boolean tells you if the peer has that piece (if it's set to true)
|
|
or if the peer miss that piece (set to false).</p>
|
|
<p><tt class="literal"><span class="pre">upload_limit</span></tt> is the number of bytes per second we are allowed to send to this
|
|
peer every second. It may be -1 if there's no limit.</p>
|
|
</div>
|
|
<div class="section" id="get-torrent-info">
|
|
<h3><a class="toc-backref" href="#id17" name="get-torrent-info">get_torrent_info()</a></h3>
|
|
<p>Returns a const reference to the <tt class="literal"><span class="pre">torrent_info</span></tt> object associated with this torrent.
|
|
This reference is valid as long as the <tt class="literal"><span class="pre">torrent_handle</span></tt> is valid, no longer. If the
|
|
<tt class="literal"><span class="pre">torrent_handle</span></tt> is invalid, <tt class="literal"><span class="pre">invalid_handle</span></tt> exception will be thrown.</p>
|
|
</div>
|
|
<div class="section" id="is-valid">
|
|
<h3><a class="toc-backref" href="#id18" name="is-valid">is_valid()</a></h3>
|
|
<p>Returns true if this handle refers to a valid torrent and false if it hasn't been initialized
|
|
or if the torrent it refers to has been aborted.</p>
|
|
</div>
|
|
</div>
|
|
<div class="section" id="address">
|
|
<h2><a class="toc-backref" href="#id19" name="address">address</a></h2>
|
|
<p>The <tt class="literal"><span class="pre">address</span></tt> class represents a name of a network endpoint (usually referred to as
|
|
IP-address) and a port number. This is the same thing as a <tt class="literal"><span class="pre">sockaddr_in</span></tt> would contain.
|
|
Its declaration looks like this:</p>
|
|
<pre class="literal-block">
|
|
class address
|
|
{
|
|
public:
|
|
address();
|
|
address(unsigned char a
|
|
, unsigned char b
|
|
, unsigned char c
|
|
, unsigned char d
|
|
, unsigned short port);
|
|
address(unsigned int addr, unsigned short port);
|
|
address(const std::string& addr, unsigned short port);
|
|
address(const address& a);
|
|
~address();
|
|
|
|
std::string as_string() const;
|
|
unsigned int ip() const;
|
|
unsigned short port() const;
|
|
|
|
bool operator<(const address& a) const;
|
|
bool operator!=(const address& a) const;
|
|
bool operator==(const address& a) const;
|
|
};
|
|
</pre>
|
|
<p>It is less-than comparable to make it possible to use it as a key in a map. <tt class="literal"><span class="pre">as_string()</span></tt> may block
|
|
while it does the DNS lookup, it returns a string that points to the address represented by the object.</p>
|
|
<p><tt class="literal"><span class="pre">ip()</span></tt> will return the 32-bit ip-address as an integer. <tt class="literal"><span class="pre">port()</span></tt> returns the port number.</p>
|
|
</div>
|
|
<div class="section" id="http-settings">
|
|
<h2><a class="toc-backref" href="#id20" name="http-settings">http_settings</a></h2>
|
|
<p>You have some control over tracker requests through the <tt class="literal"><span class="pre">http_settings</span></tt> object. You
|
|
create it and fill it with your settings and the use <tt class="literal"><span class="pre">session::set_http_settings()</span></tt>
|
|
to apply them. You have control over proxy and authorization settings and also the user-agent
|
|
that will be sent to the tracker. The user-agent is a good way to identify your client.</p>
|
|
<pre class="literal-block">
|
|
struct http_settings
|
|
{
|
|
http_settings();
|
|
std::string proxy_ip;
|
|
int proxy_port;
|
|
std::string proxy_login;
|
|
std::string proxy_password;
|
|
std::string user_agent;
|
|
int tracker_timeout;
|
|
int tracker_maximum_response_length;
|
|
};
|
|
</pre>
|
|
<p><tt class="literal"><span class="pre">tracker_timeout</span></tt> is the number of seconds the tracker connection will
|
|
wait until it considers the tracker to have timed-out. Default value is 10
|
|
seconds.</p>
|
|
<p><tt class="literal"><span class="pre">tracker_maximum_response_length</span></tt> is the maximum number of bytes in a
|
|
tracker response. If a response size passes this number it will be rejected
|
|
and the connection will be closed. On gzipped responses this size is measured
|
|
on the uncompressed data. So, if you get 20 bytes of gzip response that'll
|
|
expand to 2 megs, it will be interrupted before the entire response has been
|
|
uncompressed (given your limit is lower than 2 megs). Default limit is
|
|
1 megabyte.</p>
|
|
<p>TODO: finish document http_settings</p>
|
|
</div>
|
|
<div class="section" id="big-number">
|
|
<h2><a class="toc-backref" href="#id21" name="big-number">big_number</a></h2>
|
|
<p>Both the <tt class="literal"><span class="pre">peer_id</span></tt> and <tt class="literal"><span class="pre">sha1_hash</span></tt> types are typedefs of the class
|
|
<tt class="literal"><span class="pre">big_number</span></tt>. It represents 20 bytes of data. Its synopsis follows:</p>
|
|
<pre class="literal-block">
|
|
class big_number
|
|
{
|
|
public:
|
|
bool operator==(const big_number& n) const;
|
|
bool operator!=(const big_number& n) const;
|
|
bool operator<(const big_number& n) const;
|
|
|
|
const unsigned char* begin() const;
|
|
const unsigned char* end() const;
|
|
|
|
unsigned char* begin();
|
|
unsigned char* end();
|
|
};
|
|
</pre>
|
|
<p>The iterators gives you access to individual bytes.</p>
|
|
</div>
|
|
<div class="section" id="hasher">
|
|
<h2><a class="toc-backref" href="#id22" name="hasher">hasher</a></h2>
|
|
<p>This class creates sha1-hashes. Its declaration looks like this:</p>
|
|
<pre class="literal-block">
|
|
class hasher
|
|
{
|
|
public:
|
|
hasher();
|
|
|
|
void update(const char* data, unsigned int len);
|
|
sha1_hash final();
|
|
void reset();
|
|
};
|
|
</pre>
|
|
<p>You use it by first instantiating it, then call <tt class="literal"><span class="pre">update()</span></tt> to feed it
|
|
with data. i.e. you don't have to keep the entire buffer of which you want to
|
|
create the hash in memory. You can feed the hasher parts of it at a time. When
|
|
You have fed the hasher with all the data, you call <tt class="literal"><span class="pre">final()</span></tt> and it
|
|
will return the sha1-hash of the data.</p>
|
|
<p>If you want to reuse the hasher object once you have created a hash, you have to
|
|
call <tt class="literal"><span class="pre">reset()</span></tt> to reinitialize it.</p>
|
|
<p>The sha1-algorithm used was implemented by Steve Reid and released as public domain.
|
|
For more info, see <tt class="literal"><span class="pre">src/sha1.c</span></tt>.</p>
|
|
</div>
|
|
<div class="section" id="exceptions">
|
|
<h2><a class="toc-backref" href="#id23" name="exceptions">exceptions</a></h2>
|
|
<p>There are a number of exceptions that can be thrown from different places in libtorrent,
|
|
here's a complete list with description.</p>
|
|
<div class="section" id="invalid-handle">
|
|
<h3><a class="toc-backref" href="#id24" name="invalid-handle">invalid_handle</a></h3>
|
|
<p>This exception is thrown when querying information from a <tt class="literal"><span class="pre">torrent_handle</span></tt> that hasn't
|
|
been initialized or that has become invalid.</p>
|
|
<pre class="literal-block">
|
|
struct invalid_handle: std::exception
|
|
{
|
|
const char* what() const throw();
|
|
};
|
|
</pre>
|
|
</div>
|
|
<div class="section" id="duplicate-torrent">
|
|
<h3><a class="toc-backref" href="#id25" name="duplicate-torrent">duplicate_torrent</a></h3>
|
|
<p>This is thrown by <tt class="literal"><span class="pre">session::add_torrent()</span></tt> if the torrent already has been added to
|
|
the session.</p>
|
|
<pre class="literal-block">
|
|
struct duplicate_torrent: std::exception
|
|
{
|
|
const char* what() const throw();
|
|
};
|
|
</pre>
|
|
</div>
|
|
<div class="section" id="invalid-encoding">
|
|
<h3><a class="toc-backref" href="#id26" name="invalid-encoding">invalid_encoding</a></h3>
|
|
<p>This is thrown by <tt class="literal"><span class="pre">bdecode()</span></tt> if the input data is not a valid bencoding.</p>
|
|
<pre class="literal-block">
|
|
struct invalid_encoding: std::exception
|
|
{
|
|
const char* what() const throw();
|
|
};
|
|
</pre>
|
|
</div>
|
|
<div class="section" id="type-error">
|
|
<h3><a class="toc-backref" href="#id27" name="type-error">type_error</a></h3>
|
|
<p>This is thrown from the accessors of <tt class="literal"><span class="pre">entry</span></tt> if the data type of the <tt class="literal"><span class="pre">entry</span></tt> doesn't
|
|
match the type you want to extract from it.</p>
|
|
<pre class="literal-block">
|
|
struct type_error: std::runtime_error
|
|
{
|
|
type_error(const char* error);
|
|
};
|
|
</pre>
|
|
</div>
|
|
<div class="section" id="invalid-torrent-file">
|
|
<h3><a class="toc-backref" href="#id28" name="invalid-torrent-file">invalid_torrent_file</a></h3>
|
|
<p>This exception is thrown from the constructor of <tt class="literal"><span class="pre">torrent_info</span></tt> if the given bencoded information
|
|
doesn't meet the requirements on what information has to be present in a torrent file.</p>
|
|
<pre class="literal-block">
|
|
struct invalid_torrent_file: std::exception
|
|
{
|
|
const char* what() const throw();
|
|
};
|
|
</pre>
|
|
</div>
|
|
</div>
|
|
<div class="section" id="example-usage">
|
|
<h2><a class="toc-backref" href="#id29" name="example-usage">example usage</a></h2>
|
|
<div class="section" id="dump-torrent">
|
|
<h3><a class="toc-backref" href="#id30" name="dump-torrent">dump_torrent</a></h3>
|
|
<p>This is an example of a program that will take a torrent-file as a parameter and
|
|
print information about it to std out:</p>
|
|
<pre class="literal-block">
|
|
#include <iostream>
|
|
#include <fstream>
|
|
#include <iterator>
|
|
#include <exception>
|
|
#include <iomanip>
|
|
|
|
#include "libtorrent/entry.hpp"
|
|
#include "libtorrent/bencode.hpp"
|
|
#include "libtorrent/torrent_info.hpp"
|
|
|
|
|
|
int main(int argc, char* argv[])
|
|
{
|
|
using namespace libtorrent;
|
|
|
|
if (argc != 2)
|
|
{
|
|
std::cerr << "usage: dump_torrent torrent-file\n";
|
|
return 1;
|
|
}
|
|
|
|
try
|
|
{
|
|
std::ifstream in(argv[1], std::ios_base::binary);
|
|
in.unsetf(std::ios_base::skipws);
|
|
entry e = bdecode(std::istream_iterator<char>(in), std::istream_iterator<char>());
|
|
torrent_info t(e);
|
|
|
|
// print info about torrent
|
|
std::cout << "\n\n----- torrent file info -----\n\n";
|
|
std::cout << "trackers:\n";
|
|
for (std::vector<announce_entry>::const_iterator i = t.trackers().begin();
|
|
i != t.trackers().end();
|
|
++i)
|
|
{
|
|
std::cout << i->tier << ": " << i->url << "\n";
|
|
}
|
|
|
|
std::cout << "number of pieces: " << t.num_pieces() << "\n";
|
|
std::cout << "piece length: " << t.piece_length() << "\n";
|
|
std::cout << "files:\n";
|
|
for (torrent_info::file_iterator i = t.begin_files();
|
|
i != t.end_files();
|
|
++i)
|
|
{
|
|
std::cout << " " << std::setw(11) << i->size
|
|
<< " " << i->path << " " << i->filename << "\n";
|
|
}
|
|
|
|
}
|
|
catch (std::exception& e)
|
|
{
|
|
std::cout << e.what() << "\n";
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
</pre>
|
|
</div>
|
|
<div class="section" id="simple-client">
|
|
<h3><a class="toc-backref" href="#id31" name="simple-client">simple client</a></h3>
|
|
<p>This is a simple client. It doesn't have much output to keep it simple:</p>
|
|
<pre class="literal-block">
|
|
#include <iostream>
|
|
#include <fstream>
|
|
#include <iterator>
|
|
#include <exception>
|
|
|
|
#include <boost/format.hpp>
|
|
#include <boost/date_time/posix_time/posix_time.hpp>
|
|
|
|
#include "libtorrent/entry.hpp"
|
|
#include "libtorrent/bencode.hpp"
|
|
#include "libtorrent/session.hpp"
|
|
#include "libtorrent/http_settings.hpp"
|
|
|
|
int main(int argc, char* argv[])
|
|
{
|
|
using namespace libtorrent;
|
|
|
|
if (argc != 2)
|
|
{
|
|
std::cerr << "usage: ./simple_cient torrent-file\n"
|
|
"to stop the client, press return.\n";
|
|
return 1;
|
|
}
|
|
|
|
try
|
|
{
|
|
session s(6881, "E\x1");
|
|
|
|
std::ifstream in(argv[1], std::ios_base::binary);
|
|
in.unsetf(std::ios_base::skipws);
|
|
entry e = bdecode(std::istream_iterator<char>(in), std::istream_iterator<char>());
|
|
torrent_info t(e);
|
|
s.add_torrent(t, "");
|
|
|
|
// wait for the user to end
|
|
char a;
|
|
std::cin.unsetf(std::ios_base::skipws);
|
|
std::cin >> a;
|
|
}
|
|
catch (std::exception& e)
|
|
{
|
|
std::cout << e.what() << "\n";
|
|
}
|
|
return 0;
|
|
}
|
|
</pre>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div class="section" id="feedback">
|
|
<h1><a class="toc-backref" href="#id32" name="feedback">Feedback</a></h1>
|
|
<p>There's a <a class="reference" href="http://lists.sourceforge.net/lists/listinfo/libtorrent-discuss">mailing list</a>.</p>
|
|
<p>You can usually find me as hydri in <tt class="literal"><span class="pre">#btports</span> <span class="pre">@</span> <span class="pre">irc.freenode.net</span></tt>.</p>
|
|
</div>
|
|
<div class="section" id="aknowledgements">
|
|
<h1><a class="toc-backref" href="#id33" name="aknowledgements">Aknowledgements</a></h1>
|
|
<p>Written by Arvid Norberg and Daniel Wallin. Copyright (c) 2003</p>
|
|
<p>Project is hosted by sourceforge.</p>
|
|
<p><a class="reference" href="http://sourceforge.net"><img alt="sf_logo" src="http://sourceforge.net/sflogo.php?group_id=7994" /></a></p>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|