forked from premiere/premiere-libtorrent
3239 lines
113 KiB
ReStructuredText
Executable File
3239 lines
113 KiB
ReStructuredText
Executable File
============================
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libtorrent API Documentation
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============================
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:Author: Arvid Norberg, arvid@rasterbar.com
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:Version: 0.12
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.. contents:: Table of contents
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:depth: 2
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:backlinks: none
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overview
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========
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The interface of libtorrent consists of a few classes. The main class is
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the ``session``, it contains the main loop that serves all torrents.
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The basic usage is as follows:
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* construct a session
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* parse .torrent-files and add them to the session (see `bdecode() bencode()`_)
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* main loop (see session_)
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* query the torrent_handles for progress (see torrent_handle_)
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* query the session for information
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* add and remove torrents from the session at run-time
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* save resume data for all torrent_handles (optional, see
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`write_resume_data()`_)
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* destruct session object
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Each class and function is described in this manual.
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primitive network types
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=======================
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There are a few typedefs in the ``libtorrent`` namespace which pulls
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in network types from the ``asio`` namespace. These are::
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typedef asio::ip::address address;
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typedef asio::ip::address_v4 address_v4;
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typedef asio::ip::address_v6 address_v6;
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using asio::ip::tcp;
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using asio::ip::udp;
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These are declared in the ``<libtorrent/socket.hpp>`` header.
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The ``using`` statements will give easy access to::
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tcp::endpoint
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udp::endpoint
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Which are the endpoint types used in libtorrent. An endpoint is an address
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with an associated port.
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session
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=======
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The ``session`` class has the following synopsis::
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class session: public boost::noncopyable
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{
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session(fingerprint const& print
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= libtorrent::fingerprint(
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"LT", 0, 1, 0, 0));
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session(
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fingerprint const& print
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, std::pair<int, int> listen_port_range
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, char const* listen_interface = 0);
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torrent_handle add_torrent(
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torrent_info const& ti
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, boost::filesystem::path const& save_path
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, entry const& resume_data = entry()
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, bool compact_mode = true
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, int block_size = 16 * 1024);
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torrent_handle add_torrent(
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char const* tracker_url
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, sha1_hash const& info_hash
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, char const* name
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, boost::filesystem::path const& save_path
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, entry const& resume_data = entry()
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, bool compact_mode = true
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, int block_size = 16 * 1024);
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session_proxy abort();
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void remove_torrent(torrent_handle const& h);
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torrent_handle find_torrent(sha_hash const& ih);
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std::vector<torrent_handle> get_torrents() const;
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void set_settings(
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session_settings const& settings);
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void set_upload_rate_limit(int bytes_per_second);
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int upload_rate_limit() const;
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void set_download_rate_limit(int bytes_per_second);
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int download_rate_limit() const;
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void set_max_uploads(int limit);
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void set_max_connections(int limit);
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void set_max_half_open_connections(int limit);
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int num_uploads() const;
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int num_connections() const;
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void set_ip_filter(ip_filter const& f);
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session_status status() const;
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bool is_listening() const;
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unsigned short listen_port() const;
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bool listen_on(
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std::pair<int, int> const& port_range
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, char const* interface = 0);
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std::auto_ptr<alert> pop_alert();
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void set_severity_level(alert::severity_t s);
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void add_extension(boost::function<
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boost::shared_ptr<torrent_plugin>(torrent*)> ext);
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void start_dht();
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void stop_dht();
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void set_dht_settings(
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dht_settings const& settings);
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entry dht_state() const;
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void add_dht_node(std::pair<std::string
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, int> const& node);
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void add_dht_router(std::pair<std::string
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, int> const& node);
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};
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Once it's created, the session object 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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session()
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---------
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::
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session(fingerprint const& print
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= libtorrent::fingerprint("LT", 0, 1, 0, 0));
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session(fingerprint const& print
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, std::pair<int, int> listen_port_range
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, char const* listen_interface = 0);
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If the fingerprint in the first overload is omited, the client will get a default
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fingerprint stating the version of libtorrent. The fingerprint is a short string that will be
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used in the peer-id to identify the client and the client's version. For more details see the
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fingerprint_ class. The constructor that only takes a fingerprint will not open a
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listen port for the session, to get it running you'll have to call ``session::listen_on()``.
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The other constructor, that takes a port range and an interface as well as the fingerprint
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will automatically try to listen on a port on the given interface. For more information about
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the parameters, see ``listen_on()`` function.
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~session()
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----------
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The destructor of session will notify all trackers that our torrents have been shut down.
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If some trackers are down, they will time out. All this before the destructor of session
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returns. So, it's advised that any kind of interface (such as windows) are closed before
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destructing the session object. Because it can take a few second for it to finish. The
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timeout can be set with ``set_settings()``.
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abort()
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-------
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::
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session_proxy abort();
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In case you want to destruct the session asynchrounously, you can request a session
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destruction proxy. If you don't do this, the destructor of the session object will
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block while the trackers are contacted. If you keep one ``session_proxy`` to the
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session when destructing it, the destructor will not block, but start to close down
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the session, the destructor of the proxy will then synchronize the threads. So, the
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destruction of the session is performed from the ``session`` destructor call until the
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``session_proxy`` destructor call. The ``session_proxy`` does not have any operations
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on it (since the session is being closed down, no operations are allowed on it). The
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only valid operation is calling the destructor::
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class session_proxy
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{
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public:
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session_proxy();
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~session_proxy()
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};
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add_torrent()
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-------------
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::
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torrent_handle add_torrent(
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torrent_info const& ti
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, boost::filesystem::path const& save_path
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, entry const& resume_data = entry()
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, bool compact_mode = true
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, int block_size = 16 * 1024);
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torrent_handle add_torrent(
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char const* tracker_url
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, sha1_hash const& info_hash
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, char const* name
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, boost::filesystem::path const& save_path
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, entry const& resume_data = entry()
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, bool compact_mode = true
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, int block_size = 16 * 1024);
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You add torrents through the ``add_torrent()`` 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 ``save_path`` will be prepended to the directory
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structure in the torrent-file.
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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) ``add_torrent()`` will throw
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duplicate_torrent_ which derives from ``std::exception``.
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The optional parameter, ``resume_data`` can be given if up to date fast-resume data
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is available. The fast-resume data can be acquired from a running torrent by calling
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``torrent_handle::write_resume_data()``. See `fast resume`_.
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The ``compact_mode`` parameter refers to the layout of the storage for this torrent. If
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set to true (default), the storage will grow as more pieces are downloaded, and pieces
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are rearranged to finally be in their correct places once the entire torrent has been
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downloaded. If it is false, the entire storage is allocated before download begins. I.e.
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the files contained in the torrent are filled with zeros, and each downloaded piece
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is put in its final place directly when downloaded. For more info, see `storage allocation`_.
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``block_size`` sets the preferred request size, i.e. the number of bytes to request from
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a peer at a time. This block size must be a divisor of the piece size, and since the piece
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size is an even power of 2, so must the block size be. If the block size given here turns
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out to be greater than the piece size, it will simply be clamped to the piece size.
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The torrent_handle_ returned by ``add_torrent()`` 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.
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The second overload that takes a tracker url and an info-hash instead of metadata
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(``torrent_info``) can be used with torrents where (at least some) peers support
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the metadata extension. For the overload to be available, libtorrent must be built
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with extensions enabled (``TORRENT_ENABLE_EXTENSIONS`` defined). It also takes an
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optional ``name`` argument. This may be 0 in case no name should be assigned to the
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torrent. In case it's not 0, the name is used for the torrent as long as it doesn't
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have metadata. See ``torrent_handle::name``.
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remove_torrent() find_torrent() get_torrents()
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----------------------------------------------
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::
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void remove_torrent(torrent_handle const& h);
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torrent_handle find_torrent(sha_hash const& ih);
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std::vector<torrent_handle> get_torrents() const;
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``remove_torrent()`` 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.
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``find_torrent()`` looks for a torrent with the given info-hash. In case there
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is such a torrent in the session, a torrent_handle to that torrent is returned.
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In case the torrent cannot be found, an invalid torrent_handle is returned.
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See ``torrent_handle::is_valid()`` to know if the torrent was found or not.
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``get_torrents()`` returns a vector of torrent_handles to all the torrents
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currently in the session.
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set_upload_rate_limit() set_download_rate_limit() upload_rate_limit() download_rate_limit()
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-------------------------------------------------------------------------------------------
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::
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void set_upload_rate_limit(int bytes_per_second);
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void set_download_rate_limit(int bytes_per_second);
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int upload_rate_limit() const;
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int download_rate_limit() const;
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``set_upload_rate_limit()`` 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).
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``set_download_rate_limit()`` works the same way but for download rate instead
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of upload rate.
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``download_rate_limit()`` and ``upload_rate_limit()`` returns the previously
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set limits.
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set_max_uploads() set_max_connections()
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---------------------------------------
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::
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void set_max_uploads(int limit);
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void set_max_connections(int limit);
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These functions will set a global limit on the number of unchoked peers (uploads)
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and the number of connections opened. The number of connections is set to a hard
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minimum of at least two connections per torrent, so if you set a too low
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connections limit, and open too many torrents, the limit will not be met. The
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number of uploads is at least one per torrent.
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num_uploads() num_connections()
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-------------------------------
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::
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int num_uploads() const;
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int num_connections() const;
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Returns the number of currently unchoked peers and the number of connections
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(including half-open ones) respectively.
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set_max_half_open_connections()
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-------------------------------
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::
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void set_max_half_open_connections(int limit);
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Sets the maximum number of half-open connections libtorrent will have when
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connecting to peers. A half-open connection is one where connect() has been
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called, but the connection still hasn't been established (nor failed). Windows
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XP Service Pack 2 sets a default, system wide, limit of the number of half-open
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connections to 10. So, this limit can be used to work nicer together with
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other network applications on that system. The default is to have no limit,
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and passing -1 as the limit, means to have no limit. When limiting the number
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of simultaneous connection attempts, peers will be put in a queue waiting for
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their turn to get connected.
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set_ip_filter()
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---------------
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::
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void set_ip_filter(ip_filter const& filter);
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Sets a filter that will be used to reject and accept incoming as well as outgoing
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connections based on their originating ip address. The default filter will allow
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connections to any ip address. To build a set of rules for which addresses are
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accepted and not, see ip_filter_.
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status()
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--------
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::
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session_status status() const;
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``status()`` returns session wide-statistics and status. The ``session_status``
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struct has the following members::
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struct session_status
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{
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bool has_incoming_connections;
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float upload_rate;
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float download_rate;
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float payload_upload_rate;
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float payload_download_rate;
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size_type total_download;
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size_type total_upload;
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size_type total_payload_download;
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size_type total_payload_upload;
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int num_peers;
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int dht_nodes;
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int dht_cache_nodes;
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int dht_torrents;
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};
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``has_incoming_connections`` is false as long as no incoming connections have been
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established on the listening socket. Every time you change the listen port, this will
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be reset to false.
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``upload_rate``, ``download_rate``, ``payload_download_rate`` and ``payload_upload_rate``
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are the total download and upload rates accumulated from all torrents. The payload
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versions is the payload download only.
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``total_download`` and ``total_upload`` are the total number of bytes downloaded and
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uploaded to and from all torrents. ``total_payload_download`` and ``total_payload_upload``
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are the same thing but where only the payload is considered.
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``num_peers`` is the total number of peer connections this session have.
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``dht_nodes``, ``dht_cache_nodes`` and ``dht_torrents`` are only available when
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built with DHT support. They are all set to 0 if the DHT isn't running. When
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the DHT is running, ``dht_nodes`` is set to the number of nodes in the routing
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table. This number only includes *active* nodes, not cache nodes. The
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``dht_cache_nodes`` is set to the number of nodes in the node cache. These nodes
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are used to replace the regular nodes in the routing table in case any of them
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becomes unresponsive.
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``dht_torrents`` are the number of torrents tracked by the DHT at the moment.
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is_listening() listen_port() listen_on()
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----------------------------------------
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::
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bool is_listening() const;
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unsigned short listen_port() const;
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bool listen_on(
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std::pair<int, int> const& port_range
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, char const* interface = 0);
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``is_listening()`` will tell you whether or not the session has successfully
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opened a listening port. If it hasn't, this function will return false, and
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then you can use ``listen_on()`` to make another try.
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``listen_port()`` returns the port we ended up listening on. Since you just pass
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a port-range to the constructor and to ``listen_on()``, to know which port it
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ended up using, you have to ask the session using this function.
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``listen_on()`` will change the listen port and/or the listen interface. If the
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session is already listening on a port, this socket will be closed and a new socket
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will be opened with these new settings. The port range is the ports it will try
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to listen on, if the first port fails, it will continue trying the next port within
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the range and so on. The interface parameter can be left as 0, in that case the
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os will decide which interface to listen on, otherwise it should be the ip-address
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of the interface you want the listener socket bound to. ``listen_on()`` returns true
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if it managed to open the socket, and false if it failed. If it fails, it will also
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generate an appropriate alert (listen_failed_alert_).
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The interface parameter can also be a hostname that will resolve to the device you
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want to listen on.
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pop_alert() set_severity_level()
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--------------------------------
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::
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std::auto_ptr<alert> pop_alert();
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void set_severity_level(alert::severity_t s);
|
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``pop_alert()`` is used to ask the session if any errors or events has occurred. With
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``set_severity_level()`` you can filter how serious the event has to be for you to
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receive it through ``pop_alert()``. For information, see alerts_.
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||
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add_extension()
|
||
---------------
|
||
|
||
::
|
||
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||
void add_extension(boost::function<
|
||
boost::shared_ptr<torrent_plugin>(torrent*)> ext);
|
||
|
||
This function adds an extension to this session. The argument is a function
|
||
object that is called with a ``torrent*`` and which should return a
|
||
``boost::shared_ptr<torrent_plugin>``. To write custom plugins, see
|
||
`libtorrent plugins`_. The main plugins implemented in libtorrent are:
|
||
|
||
metadata extension
|
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Allows peers to download the metadata (.torren files) from the swarm
|
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directly. Makes it possible to join a swarm with just a tracker and
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info-hash.
|
||
|
||
uTorrent peer exchange
|
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Exchanges peers between clients.
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||
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||
To use these, imclude ``<libtorrent/extensions/metadata_transfer.hpp>``
|
||
or ``<libtorrent/extensions/ut_pex.hpp>``. The functions to pass in to
|
||
``add_extension()`` are ``libtorrent::create_metadata_plugin`` and
|
||
``libtorrent::create_ut_pex_plugin`` respectively.
|
||
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e.g.
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||
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||
::
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ses.add_extension(&libtorrent::create_metadata_plugin);
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ses.add_extension(&libtorrent::create_ut_pex_plugin);
|
||
|
||
.. _`libtorrent plugins`: libtorrent_plugins.html
|
||
|
||
start_dht() stop_dht() set_dht_settings() dht_state()
|
||
-----------------------------------------------------
|
||
|
||
::
|
||
|
||
void start_dht(entry const& startup_state);
|
||
void stop_dht();
|
||
void set_dht_settings(dht_settings const& settings);
|
||
entry dht_state() const;
|
||
|
||
These functions are not available in case ``TORRENT_DISABLE_DHT`` is
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||
defined. ``start_dht`` starts the dht node and makes the trackerless service
|
||
available to torrents. The startup state is optional and can contain nodes
|
||
and the node id from the previous session. The dht node state is a bencoded
|
||
dictionary with the following entries:
|
||
|
||
``nodes``
|
||
A list of strings, where each string is a node endpoint encoded in binary. If
|
||
the string is 6 bytes long, it is an IPv4 address of 4 bytes, encoded in
|
||
network byte order (big endian), followed by a 2 byte port number (also
|
||
network byte order). If the string is 18 bytes long, it is 16 bytes of IPv6
|
||
address followed by a 2 bytes port number (also network byte order).
|
||
|
||
``node-id``
|
||
The node id written as a readable string as a hexadecimal number.
|
||
|
||
``dht_state`` will return the current state of the dht node, this can be used
|
||
to start up the node again, passing this entry to ``start_dht``. It is a good
|
||
idea to save this to disk when the session is closed, and read it up again
|
||
when starting.
|
||
|
||
If the port the DHT is supposed to listen on is already in use, and exception
|
||
is thrown, ``asio::error``.
|
||
|
||
``stop_dht`` stops the dht node.
|
||
|
||
``add_dht_node`` adds a node to the routing table. This can be used if your
|
||
client has its own source of bootstrapping nodes.
|
||
|
||
``set_dht_settings`` sets some parameters availavle to the dht node. The
|
||
struct has the following members::
|
||
|
||
struct dht_settings
|
||
{
|
||
int max_peers_reply;
|
||
int search_branching;
|
||
int service_port;
|
||
int max_fail_count;
|
||
};
|
||
|
||
``max_peers_reply`` is the maximum number of peers the node will send in
|
||
response to a ``get_peers`` message from another node.
|
||
|
||
``search_branching`` is the number of concurrent search request the node will
|
||
send when announcing and refreshing the routing table. This parameter is
|
||
called alpha in the kademlia paper.
|
||
|
||
``service_port`` is the udp port the node will listen to.
|
||
|
||
``max_fail_count`` is the maximum number of failed tries to contact a node
|
||
before it is removed from the routing table. If there are known working nodes
|
||
that are ready to replace a failing node, it will be replaced immediately,
|
||
this limit is only used to clear out nodes that don't have any node that can
|
||
replace them.
|
||
|
||
|
||
add_dht_node() add_dht_router()
|
||
-------------------------------
|
||
|
||
::
|
||
|
||
void add_dht_node(std::pair<std::string, int> const& node);
|
||
void add_dht_router(std::pair<std::string, int> const& node);
|
||
|
||
``add_dht_node`` takes a host name and port pair. That endpoint will be
|
||
pinged, and if a valid DHT reply is received, the node will be added to
|
||
the routing table.
|
||
|
||
``add_dht_router`` adds the given endpoint to a list of DHT router nodes.
|
||
If a search is ever made while the routing table is empty, those nodes will
|
||
be used as backups. Nodes in the router node list will also never be added
|
||
to the regular routing table, which effectively means they are only used
|
||
for bootstrapping, to keep the load off them.
|
||
|
||
An example routing node that you could typically add is
|
||
``router.bittorrent.com``.
|
||
|
||
|
||
entry
|
||
=====
|
||
|
||
The ``entry`` class represents one node in a bencoded hierarchy. It works as a
|
||
variant type, it can be either a list, a dictionary (``std::map``), an integer
|
||
or a string. This is its synopsis::
|
||
|
||
class entry
|
||
{
|
||
public:
|
||
|
||
typedef std::map<std::string, entry> dictionary_type;
|
||
typedef std::string string_type;
|
||
typedef std::list<entry> list_type;
|
||
typedef size_type integer_type;
|
||
|
||
enum data_type
|
||
{
|
||
int_t,
|
||
string_t,
|
||
list_t,
|
||
dictionary_t,
|
||
undefined_t
|
||
};
|
||
|
||
data_type type() const;
|
||
|
||
entry(dictionary_type const&);
|
||
entry(string_type const&);
|
||
entry(list_type const&);
|
||
entry(integer_type const&);
|
||
|
||
entry();
|
||
entry(data_type t);
|
||
entry(entry const& e);
|
||
~entry();
|
||
|
||
void operator=(entry const& e);
|
||
void operator=(dictionary_type const&);
|
||
void operator=(string_type const&);
|
||
void operator=(list_type const&);
|
||
void operator=(integer_type const&);
|
||
|
||
integer_type& integer();
|
||
integer_type const& integer() const;
|
||
string_type& string();
|
||
string_type const& string() const;
|
||
list_type& list();
|
||
list_type const& list() const;
|
||
dictionary_type& dict();
|
||
dictionary_type const& dict() const;
|
||
|
||
// these functions requires that the entry
|
||
// is a dictionary, otherwise they will throw
|
||
entry& operator[](char const* key);
|
||
entry& operator[](std::string const& key);
|
||
entry const& operator[](char const* key) const;
|
||
entry const& operator[](std::string const& key) const;
|
||
entry* find_key(char const* key);
|
||
entry const* find_key(char const* key) const;
|
||
|
||
void print(std::ostream& os, int indent = 0) const;
|
||
};
|
||
|
||
*TODO: finish documentation of entry.*
|
||
|
||
integer() string() list() dict() type()
|
||
---------------------------------------
|
||
|
||
::
|
||
|
||
integer_type& integer();
|
||
integer_type const& integer() const;
|
||
string_type& string();
|
||
string_type const& string() const;
|
||
list_type& list();
|
||
list_type const& list() const;
|
||
dictionary_type& dict();
|
||
dictionary_type const& dict() const;
|
||
|
||
The ``integer()``, ``string()``, ``list()`` and ``dict()`` functions
|
||
are accessors that return the respective type. If the ``entry`` object isn't of the
|
||
type you request, the accessor will throw type_error_ (which derives from
|
||
``std::runtime_error``). You can ask an ``entry`` for its type through the
|
||
``type()`` function.
|
||
|
||
The ``print()`` function is there for debug purposes only.
|
||
|
||
If you want to create an ``entry`` you give it the type you want it to have in its
|
||
constructor, and then use one of the non-const accessors to get a reference which you then
|
||
can assign the value you want it to have.
|
||
|
||
The typical code to get info from a torrent file will then look like this::
|
||
|
||
entry torrent_file;
|
||
// ...
|
||
|
||
// throws if this is not a dictionary
|
||
entry::dictionary_type const& dict = torrent_file.dict();
|
||
entry::dictionary_type::const_iterator i;
|
||
i = dict.find("announce");
|
||
if (i != dict.end())
|
||
{
|
||
std::string tracker_url = i->second.string();
|
||
std::cout << tracker_url << "\n";
|
||
}
|
||
|
||
|
||
The following code is equivalent, but a little bit shorter::
|
||
|
||
entry torrent_file;
|
||
// ...
|
||
|
||
// throws if this is not a dictionary
|
||
if (entry* i = torrent_file.find_key("announce"))
|
||
{
|
||
std::string tracker_url = i->string();
|
||
std::cout << tracker_url << "\n";
|
||
}
|
||
|
||
|
||
To make it easier to extract information from a torrent file, the class torrent_info_
|
||
exists.
|
||
|
||
|
||
operator[]
|
||
----------
|
||
|
||
::
|
||
|
||
entry& operator[](char const* key);
|
||
entry& operator[](std::string const& key);
|
||
entry const& operator[](char const* key) const;
|
||
entry const& operator[](std::string const& key) const;
|
||
|
||
All of these functions requires the entry to be a dictionary, if it isn't they
|
||
will throw ``libtorrent::type_error``.
|
||
|
||
The non-const versions of the ``operator[]`` will return a reference to either
|
||
the existing element at the given key or, if there is no element with the
|
||
given key, a reference to a newly inserted element at that key.
|
||
|
||
The const version of ``operator[]`` will only return a reference to an
|
||
existing element at the given key. If the key is not found, it will throw
|
||
``libtorrent::type_error``.
|
||
|
||
|
||
find_key()
|
||
----------
|
||
|
||
::
|
||
|
||
entry* find_key(char const* key);
|
||
entry const* find_key(char const* key) const;
|
||
|
||
These functions requires the entry to be a dictionary, if it isn't they
|
||
will throw ``libtorrent::type_error``.
|
||
|
||
They will look for an element at the given key in the dictionary, if the
|
||
element cannot be found, they will return 0. If an element with the given
|
||
key is found, the return a pointer to it.
|
||
|
||
|
||
torrent_info
|
||
============
|
||
|
||
The ``torrent_info`` has the following synopsis::
|
||
|
||
class torrent_info
|
||
{
|
||
public:
|
||
|
||
torrent_info();
|
||
torrent_info(sha1_hash const& info_hash);
|
||
torrent_info(entry const& torrent_file);
|
||
|
||
entry create_torrent() const;
|
||
void set_comment(char const* str);
|
||
void set_piece_size(int size);
|
||
void set_creator(char const* str);
|
||
void set_hash(int index, sha1_hash const& h);
|
||
void add_tracker(std::string const& url, int tier = 0);
|
||
void add_file(boost::filesystem::path file, size_type size);
|
||
void add_url_seed(std::string const& url);
|
||
|
||
typedef std::vector<file_entry>::const_iterator file_iterator;
|
||
typedef std::vector<file_entry>::const_reverse_iterator
|
||
reverse_file_iterator;
|
||
|
||
file_iterator begin_files() const;
|
||
file_iterator end_files() const;
|
||
reverse_file_iterator rbegin_files() const;
|
||
reverse_file_iterator rend_files() const;
|
||
|
||
int num_files() const;
|
||
file_entry const& file_at(int index) const;
|
||
|
||
std::vector<file_slice> map_block(int piece, size_type offset
|
||
, int size) const;
|
||
peer_request map_file(int file_index, size_type file_offset
|
||
, int size) const;
|
||
|
||
std::vector<announce_entry> const& trackers() const;
|
||
|
||
bool priv() const;
|
||
void set_priv(bool v);
|
||
|
||
std::vector<std::string> const& url_seeds() const;
|
||
|
||
size_type total_size() const;
|
||
size_type piece_length() const;
|
||
int num_pieces() const;
|
||
sha1_hash const& info_hash() const;
|
||
std::string const& name() const;
|
||
std::string const& comment() const;
|
||
std::string const& creator() const;
|
||
|
||
std::vector<std::pair<std::string, int> > const& nodes() const;
|
||
void add_node(std::pair<std::string, int> const& node);
|
||
|
||
boost::optional<boost::posix_time::ptime>
|
||
creation_date() const;
|
||
|
||
void print(std::ostream& os) const;
|
||
|
||
size_type piece_size(unsigned int index) const;
|
||
sha1_hash const& hash_for_piece(unsigned int index) const;
|
||
};
|
||
|
||
torrent_info()
|
||
--------------
|
||
|
||
::
|
||
|
||
torrent_info();
|
||
torrent_info(sha1_hash const& info_hash);
|
||
torrent_info(entry const& torrent_file);
|
||
|
||
The default constructor of ``torrent_info`` is used when creating torrent files. It will
|
||
initialize the object to an empty torrent, containing no files. The info hash will be set
|
||
to 0 when this constructor is used. To use the empty ``torrent_info`` object, add files
|
||
and piece hashes, announce URLs and optionally a creator tag and comment. To do this you
|
||
use the members ``set_comment()``, ``set_piece_size()``, ``set_creator()``, ``set_hash()``
|
||
etc.
|
||
|
||
The constructor that takes an info-hash is identical to the default constructor with the
|
||
exception that it will initialize the info-hash to the given value. This is used internally
|
||
when downloading torrents without the metadata. The metadata will be created by libtorrent
|
||
as soon as it has been downloaded from the swarm.
|
||
|
||
The last constructor is the one that is used in most cases. It will create a ``torrent_info``
|
||
object from the information found in the given torrent_file. The ``entry`` represents a tree
|
||
node in an bencoded file. To load an ordinary .torrent file into an ``entry``, use bdecode(),
|
||
see `bdecode() bencode()`_.
|
||
|
||
set_comment() set_piece_size() set_creator() set_hash() add_tracker() add_file()
|
||
--------------------------------------------------------------------------------
|
||
|
||
::
|
||
|
||
void set_comment(char const* str);
|
||
void set_piece_size(int size);
|
||
void set_creator(char const* str);
|
||
void set_hash(int index, sha1_hash const& h);
|
||
void add_tracker(std::string const& url, int tier = 0);
|
||
void add_file(boost::filesystem::path file, size_type size);
|
||
|
||
These files are used when creating a torrent file. ``set_comment()`` will simply set
|
||
the comment that belongs to this torrent. The comment can be retrieved with the
|
||
``comment()`` member. The string should be UTF-8 encoded.
|
||
|
||
``set_piece_size()`` will set the size of each piece in this torrent. The piece size must
|
||
be an even multiple of 2. i.e. usually something like 256 kiB, 512 kiB, 1024 kiB etc. The
|
||
size is given in number of bytes.
|
||
|
||
``set_creator()`` is an optional attribute that can be used to identify your application
|
||
that was used to create the torrent file. The string should be UTF-8 encoded.
|
||
|
||
``set_hash()`` writes the hash for the piece with the given piece-index. You have to call
|
||
this function for every piece in the torrent. Usually the hasher_ is used to calculate
|
||
the sha1-hash for a piece.
|
||
|
||
``add_tracker()`` adds a tracker to the announce-list. The ``tier`` determines the order in
|
||
which the trackers are to be tried. For more information see `trackers()`_.
|
||
|
||
``add_file()`` adds a file to the torrent. The order in which you add files will determine
|
||
the order in which they are placed in the torrent file. You have to add at least one file
|
||
to the torrent. The ``path`` you give has to be a relative path from the root directory
|
||
of the torrent. The ``size`` is given in bytes.
|
||
|
||
When you have added all the files and hashes to your torrent, you can generate an ``entry``
|
||
which then can be encoded as a .torrent file. You do this by calling `create_torrent()`_.
|
||
|
||
For a complete example of how to create a torrent from a file structure, see make_torrent_.
|
||
|
||
|
||
create_torrent()
|
||
----------------
|
||
|
||
::
|
||
|
||
entry create_torrent();
|
||
|
||
Returns an ``entry`` representing the bencoded tree of data that makes up a .torrent file.
|
||
You can save this data as a torrent file with bencode() (see `bdecode() bencode()`_), for a
|
||
complete example, see make_torrent_.
|
||
|
||
.. _make_torrent: examples.html#make_torrent
|
||
|
||
This function is not const because it will also set the info-hash of the ``torrent_info``
|
||
object.
|
||
|
||
Note that a torrent file must include at least one file, and it must have at
|
||
least one tracker url or at least one DHT node.
|
||
|
||
|
||
begin_files() end_files() rbegin_files() rend_files()
|
||
-----------------------------------------------------
|
||
|
||
::
|
||
|
||
file_iterator begin_files() const;
|
||
file_iterator end_files() const;
|
||
reverse_file_iterator rbegin_files() const;
|
||
reverse_file_iterator rend_files() const;
|
||
|
||
This class will need some explanation. First of all, to get a list of all files
|
||
in the torrent, you can use ``begin_files()``, ``end_files()``,
|
||
``rbegin_files()`` and ``rend_files()``. These will give you standard vector
|
||
iterators with the type ``file_entry``.
|
||
|
||
The ``path`` is the full (relative) path of each file. i.e. if it is a multi-file
|
||
torrent, all the files starts with a directory with the same name as ``torrent_info::name()``.
|
||
The filenames are encoded with UTF-8.
|
||
|
||
``size`` is the size of the file (in bytes) and ``offset`` is the byte offset
|
||
of the file within the torrent. i.e. the sum of all the sizes of the files
|
||
before this one in the file list this one in the file list.
|
||
|
||
``orig_path`` is set to 0 in case the path element is an exact copy of that
|
||
found in the metadata. In case the path in the original metadata was
|
||
incorrectly encoded, and had to be fixed in order to be acceptable utf-8,
|
||
the original string is preserved in ``orig_path``. The reason to keep it
|
||
is to be able to reproduce the info-section exactly, with the correct
|
||
info-hash.
|
||
|
||
::
|
||
|
||
struct file_entry
|
||
{
|
||
boost::filesystem::path path;
|
||
size_type offset;
|
||
size_type size;
|
||
boost::shared_ptr<const boost::filesystem::path> orig_path;
|
||
};
|
||
|
||
|
||
num_files() file_at()
|
||
---------------------
|
||
|
||
::
|
||
|
||
int num_files() const;
|
||
file_entry const& file_at(int index) const;
|
||
|
||
If you need index-access to files you can use the ``num_files()`` and ``file_at()``
|
||
to access files using indices.
|
||
|
||
|
||
map_block()
|
||
-----------
|
||
|
||
::
|
||
|
||
std::vector<file_slice> map_block(int piece, size_type offset
|
||
, int size) const;
|
||
|
||
This function will map a piece index, a byte offset within that piece and
|
||
a size (in bytes) into the corresponding files with offsets where that data
|
||
for that piece is supposed to be stored.
|
||
|
||
The file slice struct looks like this::
|
||
|
||
struct file_slice
|
||
{
|
||
int file_index;
|
||
size_type offset;
|
||
size_type size;
|
||
};
|
||
|
||
|
||
The ``file_index`` refers to the index of the file (in the torrent_info).
|
||
To get the path and filename, use ``file_at()`` and give the ``file_index``
|
||
as argument. The ``offset`` is the byte offset in the file where the range
|
||
starts, and ``size`` is the number of bytes this range is. The size + offset
|
||
will never be greater than the file size.
|
||
|
||
|
||
map_file()
|
||
----------
|
||
|
||
::
|
||
|
||
peer_request map_file(int file_index, size_type file_offset
|
||
, int size) const;
|
||
|
||
This function will map a range in a specific file into a range in the torrent.
|
||
The ``file_offset`` parameter is the offset in the file, given in bytes, where
|
||
0 is the start of the file.
|
||
The ``peer_request`` structure looks like this::
|
||
|
||
struct peer_request
|
||
{
|
||
int piece;
|
||
int start;
|
||
int length;
|
||
bool operator==(peer_request const& r) const;
|
||
};
|
||
|
||
``piece`` is the index of the piece in which the range starts.
|
||
``start`` is the offset within that piece where the range starts.
|
||
``length`` is the size of the range, in bytes.
|
||
|
||
The input range is assumed to be valid within the torrent. ``file_offset``
|
||
+ ``size`` is not allowed to be greater than the file size. ``file_index``
|
||
must refer to a valid file, i.e. it cannot be >= ``num_files()``.
|
||
|
||
|
||
url_seeds()
|
||
-----------
|
||
|
||
::
|
||
|
||
std::vector<std::string> const& url_seeds() const;
|
||
void add_url_seed(std::string const& url);
|
||
|
||
If there are any url-seeds in this torrent, ``url_seeds()`` will return a
|
||
vector of those urls. If you're creating a torrent file, ``add_url_seed()``
|
||
adds one url to the list of url-seeds. Currently, the only transport protocol
|
||
supported for the url is http.
|
||
|
||
See `HTTP seeding`_ for more information.
|
||
|
||
|
||
print()
|
||
-------
|
||
|
||
::
|
||
|
||
void print(std::ostream& os) const;
|
||
|
||
The ``print()`` function is there for debug purposes only. It will print the info from
|
||
the torrent file to the given outstream.
|
||
|
||
|
||
trackers()
|
||
----------
|
||
|
||
::
|
||
|
||
std::vector<announce_entry> const& trackers() const;
|
||
|
||
The ``trackers()`` function will return a sorted vector of ``announce_entry``.
|
||
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.
|
||
|
||
::
|
||
|
||
struct announce_entry
|
||
{
|
||
announce_entry(std::string const& url);
|
||
std::string url;
|
||
int tier;
|
||
};
|
||
|
||
|
||
total_size() piece_length() piece_size() num_pieces()
|
||
-----------------------------------------------------
|
||
|
||
::
|
||
|
||
size_type total_size() const;
|
||
size_type piece_length() const;
|
||
size_type piece_size(unsigned int index) const;
|
||
int num_pieces() const;
|
||
|
||
|
||
``total_size()``, ``piece_length()`` and ``num_pieces()`` 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
|
||
``piece_size()`` and ``piece_length()`` is that ``piece_size()`` takes
|
||
the piece index as argument and gives you the exact size of that piece. It will always
|
||
be the same as ``piece_length()`` except in the case of the last piece, which may
|
||
be smaller.
|
||
|
||
|
||
hash_for_piece() info_hash()
|
||
----------------------------
|
||
|
||
::
|
||
|
||
size_type piece_size(unsigned int index) const;
|
||
sha1_hash const& hash_for_piece(unsigned int index) const;
|
||
|
||
``hash_for_piece()`` takes a piece-index and returns the 20-bytes sha1-hash for that
|
||
piece and ``info_hash()`` returns the 20-bytes sha1-hash for the info-section of the
|
||
torrent file. For more information on the ``sha1_hash``, see the big_number_ class.
|
||
``info_hash()`` will only return a valid hash if the torrent_info was read from a
|
||
``.torrent`` file or if an ``entry`` was created from it (through ``create_torrent``).
|
||
|
||
|
||
name() comment() creation_date() creator()
|
||
------------------------------------------
|
||
|
||
::
|
||
|
||
std::string const& name() const;
|
||
std::string const& comment() const;
|
||
boost::optional<boost::posix_time::ptime> creation_date() const;
|
||
|
||
``name()`` returns the name of the torrent.
|
||
|
||
``comment()`` returns the comment associated with the torrent. If there's no comment,
|
||
it will return an empty string. ``creation_date()`` returns a `boost::posix_time::ptime`__
|
||
object, representing the time when this torrent file was created. If there's no time stamp
|
||
in the torrent file, this will return a date of January 1:st 1970.
|
||
|
||
Both the name and the comment is UTF-8 encoded strings.
|
||
|
||
``creator()`` returns the creator string in the torrent. If there is no creator string
|
||
it will return an empty string.
|
||
|
||
__ http://www.boost.org/libs/date_time/doc/class_ptime.html
|
||
|
||
|
||
priv() set_priv()
|
||
-----------------
|
||
|
||
::
|
||
|
||
bool priv() const;
|
||
void set_priv(bool v);
|
||
|
||
``priv()`` returns true if this torrent is private. i.e., it should not be
|
||
distributed on the trackerless network (the kademlia DHT).
|
||
|
||
``set_priv()`` sets or clears the private flag on this torrent.
|
||
|
||
|
||
nodes()
|
||
-------
|
||
|
||
::
|
||
|
||
std::vector<std::pair<std::string, int> > const& nodes() const;
|
||
|
||
If this torrent contains any DHT nodes, they are put in this vector in their original
|
||
form (host name and port number).
|
||
|
||
|
||
add_node()
|
||
----------
|
||
|
||
::
|
||
|
||
void add_node(std::pair<std::string, int> const& node);
|
||
|
||
This is used when creating torrent. Use this to add a known DHT node. It may
|
||
be used, by the client, to bootstrap into the DHT network.
|
||
|
||
|
||
torrent_handle
|
||
==============
|
||
|
||
You will usually have to store your torrent handles somewhere, since it's the
|
||
object through which you retrieve information about the torrent and aborts the torrent.
|
||
Its declaration looks like this::
|
||
|
||
struct torrent_handle
|
||
{
|
||
torrent_handle();
|
||
|
||
torrent_status status();
|
||
void file_progress(std::vector<float>& fp);
|
||
void get_download_queue(std::vector<partial_piece_info>& queue) const;
|
||
void get_peer_info(std::vector<peer_info>& v) const;
|
||
torrent_info const& get_torrent_info() const;
|
||
bool is_valid() const;
|
||
|
||
std::string name() const;
|
||
|
||
entry write_resume_data() const;
|
||
void force_reannounce() const;
|
||
void connect_peer(asio::ip::tcp::endpoint const& adr) const;
|
||
|
||
void set_tracker_login(std::string const& username
|
||
, std::string const& password) const;
|
||
|
||
std::vector<announce_entry> const& trackers() const;
|
||
void replace_trackers(std::vector<announce_entry> const&);
|
||
|
||
void add_url_seed(std::string const& url);
|
||
|
||
void set_ratio(float ratio) const;
|
||
void set_max_uploads(int max_uploads) const;
|
||
void set_max_connections(int max_connections) const;
|
||
void set_upload_limit(int limit) const;
|
||
void set_download_limit(int limit) const;
|
||
void set_sequenced_download_threshold(int threshold) const;
|
||
|
||
void set_peer_upload_limit(asio::ip::tcp::endpoint ip, int limit) const;
|
||
void set_peer_download_limit(asio::ip::tcp::endpoint ip, int limit) const;
|
||
|
||
void use_interface(char const* net_interface) const;
|
||
|
||
void pause() const;
|
||
void resume() const;
|
||
bool is_paused() const;
|
||
bool is_seed() const;
|
||
|
||
void resolve_countries(bool r);
|
||
bool resolve_countries() const;
|
||
|
||
void filter_piece(int index, bool filter) const;
|
||
void filter_pieces(std::vector<bool> const& bitmask) const;
|
||
bool is_piece_filtered(int index) const;
|
||
std::vector<bool> filtered_pieces() const;
|
||
|
||
void filter_files(std::vector<bool> const& files) const;
|
||
|
||
bool has_metadata() const;
|
||
|
||
boost::filesystem::path save_path() const;
|
||
bool move_storage(boost::filesystem::path const& save_path) const;
|
||
|
||
sha1_hash info_hash() const;
|
||
|
||
bool operator==(torrent_handle const&) const;
|
||
bool operator!=(torrent_handle const&) const;
|
||
bool operator<(torrent_handle const&) const;
|
||
};
|
||
|
||
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 on an uninitialized handle, it will throw ``invalid_handle``.
|
||
|
||
.. warning:: All operations on a ``torrent_handle`` may throw invalid_handle_
|
||
exception, in case the handle is no longer refering to a torrent. There are
|
||
two exceptions, ``info_hash()`` and ``is_valid()`` will never throw.
|
||
Since the torrents are processed by a background thread, there is no
|
||
guarantee that a handle will remain valid between two calls.
|
||
|
||
*TODO: document filter_piece(), filter_pieces(), is_piece_filtered(), filtered_pieces() and filter_files()*
|
||
|
||
file_progress()
|
||
---------------
|
||
|
||
::
|
||
|
||
void file_progress(std::vector<float>& fp);
|
||
|
||
This function fills in the supplied vector with the progress (a value in the
|
||
range [0, 1]) describing the download progress of each file in this torrent.
|
||
The progress values are ordered the same as the files in the `torrent_info`_.
|
||
This operation is not very cheap.
|
||
|
||
|
||
save_path()
|
||
-----------
|
||
|
||
::
|
||
|
||
boost::filesystem::path save_path() const;
|
||
|
||
``save_path()`` returns the path that was given to `add_torrent()`_ when this torrent
|
||
was started.
|
||
|
||
move_storage()
|
||
--------------
|
||
|
||
::
|
||
|
||
bool move_storage(boost::filesystem::path const& save_path) const;
|
||
|
||
Moves the file(s) that this torrent are currently seeding from or downloading to. This
|
||
operation will only have the desired effect if the given ``save_path`` is located on
|
||
the same drive as the original save path. If the move operation fails, this function
|
||
returns false, otherwise true. Post condition for successful operation is:
|
||
``save_path() == save_path``.
|
||
|
||
|
||
force_reannounce()
|
||
------------------
|
||
|
||
::
|
||
|
||
void force_reannounce() const;
|
||
|
||
``force_reannounce()`` will force this torrent to do another tracker request, to receive new
|
||
peers. If the torrent is invalid, queued or in checking mode, this functions will throw
|
||
invalid_handle_.
|
||
|
||
|
||
connect_peer()
|
||
--------------
|
||
|
||
::
|
||
|
||
void connect_peer(asio::ip::tcp::endpoint const& adr) const;
|
||
|
||
``connect_peer()`` is a way to manually connect to peers that one believe is a part of the
|
||
torrent. If the peer does not respond, or is not a member of this torrent, it will simply
|
||
be disconnected. No harm can be done by using this other than an unnecessary connection
|
||
attempt is made. If the torrent is uninitialized or in queued or checking mode, this
|
||
will throw invalid_handle_.
|
||
|
||
|
||
name()
|
||
------
|
||
|
||
::
|
||
|
||
std::string name() const;
|
||
|
||
Returns the name of the torrent. i.e. the name from the metadata associated with it. In
|
||
case the torrent was started without metadata, and hasn't completely received it yet,
|
||
it returns the name given to it when added to the session. See ``session::add_torrent``.
|
||
|
||
|
||
set_ratio()
|
||
-----------
|
||
|
||
::
|
||
|
||
void set_ratio(float ratio) const;
|
||
|
||
``set_ratio()`` sets the desired download / upload ratio. If set to 0, it is considered being
|
||
infinite. i.e. the client will always upload as much as it can, no matter how much it gets back
|
||
in return. With this setting it will work much like the standard clients.
|
||
|
||
Besides 0, the ratio can be set to any number greater than or equal to 1. It means how much to
|
||
attempt to upload in return for each download. e.g. if set to 2, the client will try to upload
|
||
2 bytes for every byte received. The default setting for this is 0, which will make it work
|
||
as a standard client.
|
||
|
||
|
||
set_upload_limit() set_download_limit()
|
||
---------------------------------------
|
||
|
||
::
|
||
|
||
void set_upload_limit(int limit) const;
|
||
void set_download_limit(int limit) const;
|
||
|
||
``set_upload_limit`` will limit the upload bandwidth used by this particular torrent to the
|
||
limit you set. It is given as the number of bytes per second the torrent is allowed to upload.
|
||
``set_download_limit`` works the same way but for download bandwidth instead of upload bandwidth.
|
||
Note that setting a higher limit on a torrent then the global limit (``session::set_upload_rate_limit``)
|
||
will not override the global rate limit. The torrent can never upload more than the global rate
|
||
limit.
|
||
|
||
|
||
set_sequenced_download_threshold()
|
||
----------------------------------
|
||
|
||
::
|
||
|
||
void set_sequenced_download_threshold(int threshold);
|
||
|
||
sequenced-download threshold is the limit on how popular a piece has to be
|
||
(popular == inverse of rarity) to be downloaded in sequence instead of in
|
||
random (rarest first) order. It can be used to tweak disk performance in
|
||
settings where the random download property is less necessary. For example, if
|
||
the threshold is 10, all pieces which 10 or more peers have, will be downloaded
|
||
in index order. This setting defaults to 100, which means that it is disabled
|
||
in practice.
|
||
|
||
Setting this threshold to a very small value will affect the piece distribution
|
||
negatively in the swarm. It should basically only be used in situations where
|
||
the random seeks on the disk is the download bottleneck.
|
||
|
||
|
||
set_peer_upload_limit() set_peer_download_limit()
|
||
-------------------------------------------------
|
||
|
||
::
|
||
|
||
void set_peer_upload_limit(asio::ip::tcp::endpoint ip, int limit) const;
|
||
void set_peer_download_limit(asio::ip::tcp::endpoint ip, int limit) const;
|
||
|
||
Works like ``set_upload_limit`` and ``set_download_limit`` respectively, but controls individual
|
||
peer instead of the whole torrent.
|
||
|
||
pause() resume() is_paused()
|
||
----------------------------
|
||
|
||
::
|
||
|
||
void pause() const;
|
||
void resume() const;
|
||
bool is_paused() const;
|
||
|
||
``pause()``, and ``resume()`` will disconnect all peers and reconnect all peers respectively.
|
||
When a torrent is paused, it will however remember all share ratios to all peers and remember
|
||
all potential (not connected) peers. You can use ``is_paused()`` to determine if a torrent
|
||
is currently paused. Torrents may be paused automatically if there is a file error (e.g. disk full)
|
||
or something similar. See file_error_alert_.
|
||
|
||
resolve_countries()
|
||
-------------------
|
||
|
||
::
|
||
|
||
void resolve_countries(bool r);
|
||
bool resolve_countries() const;
|
||
|
||
Sets or gets the flag that derermines if countries should be resolved for the peers of this
|
||
torrent. It defaults to false. If it is set to true, the peer_info_ structure for the peers
|
||
in this torrent will have their ``country`` member set. See peer_info_ for more information
|
||
on how to interpret this field.
|
||
|
||
is_seed()
|
||
---------
|
||
|
||
::
|
||
|
||
bool is_seed() const;
|
||
|
||
Returns true if the torrent is in seed mode (i.e. if it has finished downloading).
|
||
|
||
|
||
has_metadata()
|
||
--------------
|
||
|
||
::
|
||
|
||
bool has_metadata() const;
|
||
|
||
Returns true if this torrent has metadata (either it was started from a .torrent file or the
|
||
metadata has been downloaded). The only scenario where this can return false is when the torrent
|
||
was started torrent-less (i.e. with just an info-hash and tracker ip). Note that if the torrent
|
||
doesn't have metadata, the member `get_torrent_info()`_ will throw.
|
||
|
||
set_tracker_login()
|
||
-------------------
|
||
|
||
::
|
||
|
||
void set_tracker_login(std::string const& username
|
||
, std::string const& password) const;
|
||
|
||
``set_tracker_login()`` sets a username and password that will be sent along in the HTTP-request
|
||
of the tracker announce. Set this if the tracker requires authorization.
|
||
|
||
|
||
trackers() replace_trackers()
|
||
-----------------------------
|
||
|
||
::
|
||
|
||
std::vector<announce_entry> const& trackers() const;
|
||
void replace_trackers(std::vector<announce_entry> const&) const;
|
||
|
||
``trackers()`` will return the list of trackers for this torrent. The
|
||
announce entry contains both a string ``url`` which specify the announce url
|
||
for the tracker as well as an int ``tier``, which is specifies the order in
|
||
which this tracker is tried. If you want libtorrent to use another list of
|
||
trackers for this torrent, you can use ``replace_trackers()`` which takes
|
||
a list of the same form as the one returned from ``trackers()`` and will
|
||
replace it. If you want an immediate effect, you have to call
|
||
`force_reannounce()`_.
|
||
|
||
|
||
add_url_seed()
|
||
--------------
|
||
|
||
::
|
||
|
||
void add_url_seed(std::string const& url);
|
||
|
||
``add_url_seed()`` adds another url to the torrent's list of url seeds. If the
|
||
given url already exists in that list, the call has no effect. The torrent
|
||
will connect to the server and try to download pieces from it, unless it's
|
||
paused, queued, checking or seeding.
|
||
|
||
See `HTTP seeding`_ for more information.
|
||
|
||
|
||
use_interface()
|
||
---------------
|
||
|
||
::
|
||
|
||
void use_interface(char const* net_interface) const;
|
||
|
||
``use_interface()`` sets the network interface this torrent will use when it opens outgoing
|
||
connections. By default, it uses the same interface as the session_ uses to listen on. The
|
||
parameter can be a string containing an ip-address or a hostname.
|
||
|
||
|
||
info_hash()
|
||
-----------
|
||
|
||
::
|
||
|
||
sha1_hash info_hash() const;
|
||
|
||
``info_hash()`` returns the info-hash for the torrent.
|
||
|
||
|
||
set_max_uploads() set_max_connections()
|
||
---------------------------------------
|
||
|
||
::
|
||
|
||
void set_max_uploads(int max_uploads) const;
|
||
void set_max_connections(int max_connections) const;
|
||
|
||
``set_max_uploads()`` sets the maximum number of peers that's unchoked at the same time on this
|
||
torrent. If you set this to -1, there will be no limit.
|
||
|
||
``set_max_connections()`` sets the maximum number of connection this torrent will open. If all
|
||
connections are used up, incoming connections may be refused or poor connections may be closed.
|
||
This must be at least 2. The default is unlimited number of connections. If -1 is given to the
|
||
function, it means unlimited.
|
||
|
||
|
||
write_resume_data()
|
||
-------------------
|
||
|
||
::
|
||
|
||
entry write_resume_data() const;
|
||
|
||
``write_resume_data()`` generates fast-resume data and returns it as an entry_. This entry_
|
||
is suitable for being bencoded. For more information about how fast-resume works, see `fast resume`_.
|
||
|
||
There are three cases where this function will just return an empty ``entry``:
|
||
|
||
1. The torrent handle is invalid.
|
||
2. The torrent is checking (or is queued for checking) its storage, it will obviously
|
||
not be ready to write resume data.
|
||
3. The torrent hasn't received valid metadata and was started without metadata
|
||
(see libtorrent's `metadata from peers`_ extension)
|
||
|
||
Note that by the time this function returns, the resume data may already be invalid if the torrent
|
||
is still downloading! The recommended practice is to first pause the torrent, then generate the
|
||
fast resume data, and then close it down.
|
||
|
||
|
||
status()
|
||
--------
|
||
|
||
::
|
||
|
||
torrent_status status() const;
|
||
|
||
``status()`` will return a structure with information about the status of this
|
||
torrent. If the torrent_handle_ is invalid, it will throw invalid_handle_ exception.
|
||
See torrent_status_.
|
||
|
||
|
||
get_download_queue()
|
||
--------------------
|
||
|
||
::
|
||
|
||
void get_download_queue(std::vector<partial_piece_info>& queue) const;
|
||
|
||
``get_download_queue()`` takes a non-const reference to a vector which it will fill with
|
||
information about pieces that are partially downloaded or not downloaded at all but partially
|
||
requested. The entry in the vector (``partial_piece_info``) looks like this::
|
||
|
||
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;
|
||
address peer[max_blocks_per_piece];
|
||
int num_downloads[max_blocks_per_piece];
|
||
};
|
||
|
||
``piece_index`` is the index of the piece in question. ``blocks_in_piece`` 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.
|
||
|
||
``requested_blocks`` 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 ``peer`` array. The bit-index
|
||
in the ``requested_blocks`` and ``finished_blocks`` corresponds to the array-index into
|
||
``peers`` and ``num_downloads``. The array of peers is contains the address of the
|
||
peer the piece was requested from. If a piece hasn't been requested (the bit in
|
||
``requested_blocks`` is not set) the peer array entry will be undefined.
|
||
|
||
The ``finished_blocks`` is a bitset where each bit says if the block is fully downloaded
|
||
or not. And the ``num_downloads`` array says how many times that block has been downloaded.
|
||
When a piece fails a hash verification, single blocks may be re-downloaded to
|
||
see if the hash test may pass then.
|
||
|
||
|
||
get_peer_info()
|
||
---------------
|
||
|
||
::
|
||
|
||
void get_peer_info(std::vector<peer_info>&) const;
|
||
|
||
``get_peer_info()`` 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
|
||
torrent_handle_ is invalid, it will throw invalid_handle_ exception. Each entry in
|
||
the vector contains information about that particular peer. See peer_info_.
|
||
|
||
|
||
get_torrent_info()
|
||
------------------
|
||
|
||
::
|
||
|
||
torrent_info const& get_torrent_info() const;
|
||
|
||
Returns a const reference to the torrent_info_ object associated with this torrent.
|
||
This reference is valid as long as the torrent_handle_ is valid, no longer. If the
|
||
torrent_handle_ is invalid or if it doesn't have any metadata, invalid_handle_
|
||
exception will be thrown. The torrent may be in a state without metadata only if
|
||
it was started without a .torrent file, i.e. by using the libtorrent extension of
|
||
just supplying a tracker and info-hash.
|
||
|
||
|
||
is_valid()
|
||
----------
|
||
|
||
::
|
||
|
||
bool is_valid() const;
|
||
|
||
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. Note that a handle may become invalid after
|
||
it has been added to the session. Usually this is because the storage for the torrent is
|
||
somehow invalid or if the filenames are not allowed (and hence cannot be opened/created) on
|
||
your filesystem. If such an error occurs, a file_error_alert_ is generated and all handles
|
||
that refers to that torrent will become invalid.
|
||
|
||
*TODO: document storage*
|
||
|
||
|
||
torrent_status
|
||
==============
|
||
|
||
It contains the following fields::
|
||
|
||
struct torrent_status
|
||
{
|
||
enum state_t
|
||
{
|
||
queued_for_checking,
|
||
checking_files,
|
||
connecting_to_tracker,
|
||
downloading,
|
||
finished,
|
||
seeding,
|
||
allocating
|
||
};
|
||
|
||
state_t state;
|
||
bool paused;
|
||
float progress;
|
||
boost::posix_time::time_duration next_announce;
|
||
boost::posix_time::time_duration announce_interval;
|
||
|
||
std::string current_tracker;
|
||
|
||
size_type total_download;
|
||
size_type total_upload;
|
||
|
||
size_type total_payload_download;
|
||
size_type total_payload_upload;
|
||
|
||
size_type total_failed_bytes;
|
||
size_type total_redundant_bytes;
|
||
|
||
float download_rate;
|
||
float upload_rate;
|
||
|
||
float download_payload_rate;
|
||
float upload_payload_rate;
|
||
|
||
int num_peers;
|
||
|
||
int num_complete;
|
||
int num_incomplete;
|
||
|
||
const std::vector<bool>* pieces;
|
||
int num_pieces;
|
||
|
||
size_type total_done;
|
||
size_type total_wanted_done;
|
||
size_type total_wanted;
|
||
|
||
int num_seeds;
|
||
float distributed_copies;
|
||
|
||
int block_size;
|
||
};
|
||
|
||
``progress`` 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 ``state`` member, it will be one of the following:
|
||
|
||
+--------------------------+----------------------------------------------------------+
|
||
|``queued_for_checking`` |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. |
|
||
+--------------------------+----------------------------------------------------------+
|
||
|``checking_files`` |The torrent has not started its download yet, and is |
|
||
| |currently checking existing files. |
|
||
+--------------------------+----------------------------------------------------------+
|
||
|``connecting_to_tracker`` |The torrent has sent a request to the tracker and is |
|
||
| |currently waiting for a response |
|
||
+--------------------------+----------------------------------------------------------+
|
||
|``downloading`` |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. |
|
||
+--------------------------+----------------------------------------------------------+
|
||
|``finished`` |In this state the torrent has finished downloading but |
|
||
| |still doesn't have the entire torrent. i.e. some pieces |
|
||
| |are filtered and won't get downloaded. |
|
||
+--------------------------+----------------------------------------------------------+
|
||
|``seeding`` |In this state the torrent has finished downloading and |
|
||
| |is a pure seeder. |
|
||
+--------------------------+----------------------------------------------------------+
|
||
|``allocating`` |If the torrent was started in full allocation mode, this |
|
||
| |indicates that the (disk) storage for the torrent is |
|
||
| |allocated. |
|
||
+--------------------------+----------------------------------------------------------+
|
||
|
||
|
||
When downloading, the progress is ``total_wanted_done`` / ``total_wanted``.
|
||
|
||
``paused`` is set to true if the torrent is paused and false otherwise.
|
||
|
||
``next_announce`` is the time until the torrent will announce itself to the tracker. And
|
||
``announce_interval`` is the time the tracker want us to wait until we announce ourself
|
||
again the next time.
|
||
|
||
``current_tracker`` is the URL of the last working tracker. If no tracker request has
|
||
been successful yet, it's set to an empty string.
|
||
|
||
``total_download`` and ``total_upload`` is the number of bytes downloaded and
|
||
uploaded to all peers, accumulated, *this session* only.
|
||
|
||
``total_payload_download`` and ``total_payload_upload`` counts the amount of bytes
|
||
send and received this session, but only the actual payload data (i.e the interesting
|
||
data), these counters ignore any protocol overhead.
|
||
|
||
``total_failed_bytes`` is the number of bytes that has been downloaded and that
|
||
has failed the piece hash test. In other words, this is just how much crap that
|
||
has been downloaded.
|
||
|
||
``total_redundant_bytes`` is the number of bytes that has been downloaded even
|
||
though that data already was downloaded. The reason for this is that in some
|
||
situations the same data can be downloaded by mistake. When libtorrent sends
|
||
requests to a peer, and the peer doesn't send a response within a certain
|
||
timeout, libtorrent will re-request that block. Another situation when
|
||
libtorrent may re-request blocks is when the requests it sends out are not
|
||
replied in FIFO-order (it will re-request blocks that are skipped by an out of
|
||
order block). This is supposed to be as low as possible.
|
||
|
||
``pieces`` is the bitmask that represents which pieces we have (set to true) and
|
||
the pieces we don't have. It's a pointer and may be set to 0 if the torrent isn't
|
||
downloading or seeding.
|
||
|
||
``num_pieces`` is the number of pieces that has been downloaded. It is equivalent
|
||
to: ``std::accumulate(pieces->begin(), pieces->end())``. So you don't have to
|
||
count yourself. This can be used to see if anything has updated since last time
|
||
if you want to keep a graph of the pieces up to date.
|
||
|
||
``download_rate`` and ``upload_rate`` are the total rates for all peers for this
|
||
torrent. These will usually have better precision than summing the rates from
|
||
all peers. The rates are given as the number of bytes per second. The
|
||
``download_payload_rate`` and ``upload_payload_rate`` respectively is the
|
||
total transfer rate of payload only, not counting protocol chatter. This might
|
||
be slightly smaller than the other rates, but if projected over a long time
|
||
(e.g. when calculating ETA:s) the difference may be noticeable.
|
||
|
||
``num_peers`` is the number of peers this torrent currently is connected to.
|
||
Peer connections that are in the half-open state (is attempting to connect)
|
||
or are queued for later connection attempt do not count. Although they are
|
||
visible in the peer list when you call `get_peer_info()`_.
|
||
|
||
``num_complete`` and ``num_incomplete`` are set to -1 if the tracker did not
|
||
send any scrape data in its announce reply. This data is optional and may
|
||
not be available from all trackers. If these are not -1, they are the total
|
||
number of peers that are seeding (complete) and the total number of peers
|
||
that are still downloading (incomplete) this torrent.
|
||
|
||
``total_done`` is the total number of bytes of the file(s) that we have. All
|
||
this does not necessarily has to be downloaded during this session (that's
|
||
``total_download_payload``).
|
||
|
||
``total_wanted_done`` is the number of bytes we have downloaded, only counting the
|
||
pieces that we actually want to download. i.e. excluding any pieces that we have but
|
||
are filtered as not wanted.
|
||
|
||
``total_wanted`` is the total number of bytes we want to download. This is also
|
||
excluding pieces that have been filtered.
|
||
|
||
``num_seeds`` is the number of peers that are seeding that this client is
|
||
currently connected to.
|
||
|
||
``distributed_copies`` is the number of distributed copies of the torrent.
|
||
Note that one copy may be spread out among many peers. The integer part
|
||
tells how many copies there are currently of the rarest piece(s) among the
|
||
peers this client is connected to. The fractional part tells the share of
|
||
pieces that have more copies than the rarest piece(s). For example: 2.5 would
|
||
mean that the rarest pieces have only 2 copies among the peers this torrent is
|
||
connected to, and that 50% of all the pieces have more than two copies.
|
||
|
||
If sequenced download is activated (see torrent_handle_), the distributed
|
||
copies will be saturated at the ``sequenced_download_threshold``.
|
||
|
||
``block_size`` is the size of a block, in bytes. A block is a sub piece, it
|
||
is the number of bytes that each piece request asks for and the number of
|
||
bytes that each bit in the ``partial_piece_info``'s bitset represents
|
||
(see `get_download_queue()`_). This is typically 16 kB, but it may be
|
||
larger if the pieces are larger.
|
||
|
||
peer_info
|
||
=========
|
||
|
||
It contains the following fields::
|
||
|
||
struct peer_info
|
||
{
|
||
enum
|
||
{
|
||
interesting = 0x1,
|
||
choked = 0x2,
|
||
remote_interested = 0x4,
|
||
remote_choked = 0x8,
|
||
supports_extensions = 0x10,
|
||
local_connection = 0x20,
|
||
handshake = 0x40,
|
||
connecting = 0x80,
|
||
queued = 0x100
|
||
};
|
||
unsigned int flags;
|
||
asio::ip::tcp::endpoint ip;
|
||
float up_speed;
|
||
float down_speed;
|
||
float payload_up_speed;
|
||
float payload_down_speed;
|
||
size_type total_download;
|
||
size_type total_upload;
|
||
peer_id pid;
|
||
std::vector<bool> pieces;
|
||
bool seed;
|
||
int upload_limit;
|
||
int download_limit;
|
||
|
||
char country[2];
|
||
|
||
size_type load_balancing;
|
||
|
||
int download_queue_length;
|
||
int upload_queue_length;
|
||
|
||
int downloading_piece_index;
|
||
int downloading_block_index;
|
||
int downloading_progress;
|
||
int downloading_total;
|
||
|
||
std::string client;
|
||
|
||
enum
|
||
{
|
||
standard_bittorrent = 0,
|
||
web_seed = 1
|
||
};
|
||
int connection_type;
|
||
};
|
||
|
||
The ``flags`` attribute tells you in which state the peer is. It is set to
|
||
any combination of the enums above. The following table describes each flag:
|
||
|
||
+-------------------------+-------------------------------------------------------+
|
||
| ``interesting`` | **we** are interested in pieces from this peer. |
|
||
+-------------------------+-------------------------------------------------------+
|
||
| ``choked`` | **we** have choked this peer. |
|
||
+-------------------------+-------------------------------------------------------+
|
||
| ``remote_interested`` | the peer is interested in **us** |
|
||
+-------------------------+-------------------------------------------------------+
|
||
| ``remote_choked`` | the peer has choked **us**. |
|
||
+-------------------------+-------------------------------------------------------+
|
||
| ``support_extensions`` | means that this peer supports the |
|
||
| | `extension protocol`__. |
|
||
+-------------------------+-------------------------------------------------------+
|
||
| ``local_connection`` | The connection was initiated by us, the peer has a |
|
||
| | listen port open, and that port is the same as in the |
|
||
| | address of this peer. If this flag is not set, this |
|
||
| | peer connection was opened by this peer connecting to |
|
||
| | us. |
|
||
+-------------------------+-------------------------------------------------------+
|
||
| ``handshake`` | The connection is opened, and waiting for the |
|
||
| | handshake. Until the handshake is done, the peer |
|
||
| | cannot be identified. |
|
||
+-------------------------+-------------------------------------------------------+
|
||
| ``connecting`` | The connection is in a half-open state (i.e. it is |
|
||
| | being connected). |
|
||
+-------------------------+-------------------------------------------------------+
|
||
| ``queued`` | The connection is currently queued for a connection |
|
||
| | attempt. This may happen if there is a limit set on |
|
||
| | the number of half-open TCP connections. |
|
||
+-------------------------+-------------------------------------------------------+
|
||
|
||
__ extension_protocol.html
|
||
|
||
The ``ip`` field is the IP-address to this peer. The type is an asio endpoint. For
|
||
more info, see the asio_ documentation.
|
||
|
||
.. _asio: http://asio.sf.net
|
||
|
||
``up_speed`` and ``down_speed`` contains the current upload and download speed
|
||
we have to and from this peer (including any protocol messages). The transfer rates
|
||
of payload data only are found in ``payload_up_speed`` and ``payload_down_speed``.
|
||
These figures are updated approximately once every second.
|
||
|
||
``total_download`` and ``total_upload`` 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.
|
||
|
||
``pid`` 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. See identify_client()_
|
||
|
||
``pieces`` 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).
|
||
|
||
``seed`` is true if this peer is a seed.
|
||
|
||
``upload_limit`` 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 local limit on the peer. The global
|
||
limit and the torrent limit is always enforced anyway.
|
||
|
||
``download_limit`` is the number of bytes per second this peer is allowed to
|
||
receive. -1 means it's unlimited.
|
||
|
||
``country`` is the two letter `ISO 3166 country code`__ for the country the peer
|
||
is connected from. If the country hasn't been resolved yet, both chars are set
|
||
to 0. If the resolution failed for some reason, the field is set to "--". If the
|
||
resolution service returns an invalid country code, it is set to "!!".
|
||
The ``countries.nerd.dk`` service is used to look up countries. This field will
|
||
remain set to 0 unless the torrent is set to resolve countries, see `resolve_countries()`_.
|
||
|
||
__ http://www.iso.org/iso/en/prods-services/iso3166ma/02iso-3166-code-lists/list-en1.html
|
||
|
||
``load_balancing`` is a measurement of the balancing of free download (that we get)
|
||
and free upload that we give. Every peer gets a certain amount of free upload, but
|
||
this member says how much *extra* free upload this peer has got. If it is a negative
|
||
number it means that this was a peer from which we have got this amount of free
|
||
download.
|
||
|
||
``download_queue_length`` is the number of piece-requests we have sent to this peer
|
||
that hasn't been answered with a piece yet.
|
||
|
||
``upload_queue_length`` is the number of piece-requests we have received from this peer
|
||
that we haven't answered with a piece yet.
|
||
|
||
You can know which piece, and which part of that piece, that is currently being
|
||
downloaded from a specific peer by looking at the next four members.
|
||
``downloading_piece_index`` is the index of the piece that is currently being downloaded.
|
||
This may be set to -1 if there's currently no piece downloading from this peer. If it is
|
||
>= 0, the other three members are valid. ``downloading_block_index`` is the index of the
|
||
block (or sub-piece) that is being downloaded. ``downloading_progress`` is the number
|
||
of bytes of this block we have received from the peer, and ``downloading_total`` is
|
||
the total number of bytes in this block.
|
||
|
||
``client`` is a string describing the software at the other end of the connection.
|
||
In some cases this information is not available, then it will contain a string
|
||
that may give away something about which software is running in the other end.
|
||
In the case of a web seed, the server type and version will be a part of this
|
||
string.
|
||
|
||
``connection_type`` can currently be one of ``standard_bittorrent`` or
|
||
``web_seed``. These are currently the only implemented protocols.
|
||
|
||
session_settings
|
||
================
|
||
|
||
You have some control over tracker requests through the ``session_settings`` object. You
|
||
create it and fill it with your settings and then use ``session::set_settings()``
|
||
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.
|
||
|
||
::
|
||
|
||
struct session_settings
|
||
{
|
||
session_settings();
|
||
std::string proxy_ip;
|
||
int proxy_port;
|
||
std::string proxy_login;
|
||
std::string proxy_password;
|
||
std::string user_agent;
|
||
int tracker_completion_timeout;
|
||
int tracker_receive_timeout;
|
||
int tracker_maximum_response_length;
|
||
|
||
int piece_timeout;
|
||
float request_queue_time;
|
||
int max_allowed_in_request_queue;
|
||
int max_out_request_queue;
|
||
int whole_pieces_threshold;
|
||
int peer_timeout;
|
||
int urlseed_timeout;
|
||
int urlseed_pipeline_size;
|
||
int file_pool_size;
|
||
bool allow_multiple_connections_per_ip;
|
||
bool use_dht_as_fallback;
|
||
};
|
||
|
||
``proxy_ip`` may be a hostname or ip to a http proxy to use. If this is
|
||
an empty string, no http proxy will be used.
|
||
|
||
``proxy_port`` is the port on which the http proxy listens. If ``proxy_ip``
|
||
is empty, this will be ignored.
|
||
|
||
``proxy_login`` should be the login username for the http proxy, if this
|
||
empty, the http proxy will be tried to be used without authentication.
|
||
|
||
``proxy_password`` the password string for the http proxy.
|
||
|
||
``user_agent`` this is the client identification to the tracker.
|
||
The recommended format of this string is:
|
||
"ClientName/ClientVersion libtorrent/libtorrentVersion".
|
||
This name will not only be used when making HTTP requests, but also when
|
||
sending extended headers to peers that support that extension.
|
||
|
||
``tracker_completion_timeout`` is the number of seconds the tracker
|
||
connection will wait from when it sent the request until it considers the
|
||
tracker to have timed-out. Default value is 60 seconds.
|
||
|
||
``tracker_receive_timeout`` is the number of seconds to wait to receive
|
||
any data from the tracker. If no data is received for this number of
|
||
seconds, the tracker will be considered as having timed out. If a tracker
|
||
is down, this is the kind of timeout that will occur. The default value
|
||
is 20 seconds.
|
||
|
||
``tracker_maximum_response_length`` 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.
|
||
|
||
``piece_timeout`` controls the number of seconds from a request is sent until
|
||
it times out if no piece response is returned.
|
||
|
||
``request_queue_time`` is the length of the request queue given in the number
|
||
of seconds it should take for the other end to send all the pieces. i.e. the
|
||
actual number of requests depends on the download rate and this number.
|
||
|
||
``max_allowed_in_request_queue`` is the number of outstanding block requests
|
||
a peer is allowed to queue up in the client. If a peer sends more requests
|
||
than this (before the first one has been handled) the last request will be
|
||
dropped. The higher this is, the faster upload speeds the client can get to a
|
||
single peer.
|
||
|
||
``max_out_request_queue`` is the maximum number of outstanding requests to
|
||
send to a peer. This limit takes precedence over ``request_queue_time``. i.e.
|
||
no matter the download speed, the number of outstanding requests will never
|
||
exceed this limit.
|
||
|
||
``whole_pieces_threshold`` is a limit in seconds. if a whole piece can be
|
||
downloaded in at least this number of seconds from a specific peer, the
|
||
peer_connection will prefer requesting whole pieces at a time from this peer.
|
||
The benefit of this is to better utilize disk caches by doing localized
|
||
accesses and also to make it easier to identify bad peers if a piece fails
|
||
the hash check.
|
||
|
||
``peer_timeout`` is the number of seconds the peer connection should
|
||
wait (for any activity on the peer connection) before closing it due
|
||
to time out. This defaults to 120 seconds, since that's what's specified
|
||
in the protocol specification. After half the time out, a keep alive message
|
||
is sent.
|
||
|
||
``urlseed_timeout`` is the same as ``peer_timeout`` but applies only to
|
||
url seeds. This value defaults to 20 seconds.
|
||
|
||
``urlseed_pipeline_size`` controls the pipelining with the web server. When
|
||
using persistent connections to HTTP 1.1 servers, the client is allowed to
|
||
send more requests before the first response is received. This number controls
|
||
the number of outstanding requests to use with url-seeds. Default is 5.
|
||
|
||
``file_pool_size`` is the the upper limit on the total number of files this
|
||
session will keep open. The reason why files are left open at all is that
|
||
some anti virus software hooks on every file close, and scans the file for
|
||
viruses. deferring the closing of the files will be the difference between
|
||
a usable system and a completely hogged down system. Most operating systems
|
||
also has a limit on the total number of file descriptors a process may have
|
||
open. It is usually a good idea to find this limit and set the number of
|
||
connections and the number of files limits so their sum is slightly below it.
|
||
|
||
``allow_multiple_connections_per_ip`` determines if connections from the
|
||
same IP address as existing connections should be rejected or not. Multiple
|
||
connections from the same IP address is not allowed by default, to prevent
|
||
abusive behavior by peers. It may be useful to allow such connections in
|
||
cases where simulations are run on the same machie, and all peers in a
|
||
swarm has the same IP address.
|
||
|
||
``use_dht_as_fallback`` determines how the DHT is used. If this is true
|
||
(which it is by default), the DHT will only be used for torrents where
|
||
all trackers in its tracker list has failed. Either by an explicit error
|
||
message or a time out.
|
||
|
||
ip_filter
|
||
=========
|
||
|
||
The ``ip_filter`` class is a set of rules that uniquely categorizes all
|
||
ip addresses as allowed or disallowed. The default constructor creates
|
||
a single rule that allows all addresses (0.0.0.0 - 255.255.255.255 for
|
||
the IPv4 range, and the equivalent range covering all addresses for the
|
||
IPv6 range).
|
||
|
||
::
|
||
|
||
template <class Addr>
|
||
struct ip_range
|
||
{
|
||
Addr first;
|
||
Addr last;
|
||
int flags;
|
||
};
|
||
|
||
class ip_filter
|
||
{
|
||
public:
|
||
enum access_flags { blocked = 1 };
|
||
|
||
ip_filter();
|
||
void add_rule(address first, address last, int flags);
|
||
int access(address const& addr) const;
|
||
|
||
typedef boost::tuple<std::vector<ip_range<address_v4> >
|
||
, std::vector<ip_range<address_v6> > > filter_tuple_t;
|
||
|
||
filter_tuple_t export_filter() const;
|
||
};
|
||
|
||
|
||
ip_filter()
|
||
-----------
|
||
|
||
::
|
||
|
||
ip_filter()
|
||
|
||
Creates a default filter that doesn't filter any address.
|
||
|
||
postcondition:
|
||
``access(x) == 0`` for every ``x``
|
||
|
||
|
||
add_rule()
|
||
----------
|
||
|
||
::
|
||
|
||
void add_rule(address first, address last, int flags);
|
||
|
||
Adds a rule to the filter. ``first`` and ``last`` defines a range of
|
||
ip addresses that will be marked with the given flags. The ``flags``
|
||
can currently be 0, which means allowed, or ``ip_filter::blocked``, which
|
||
means disallowed.
|
||
|
||
precondition:
|
||
``first.is_v4() == last.is_v4() && first.is_v6() == last.is_v6()``
|
||
|
||
postcondition:
|
||
``access(x) == flags`` for every ``x`` in the range [``first``, ``last``]
|
||
|
||
This means that in a case of overlapping ranges, the last one applied takes
|
||
precedence.
|
||
|
||
|
||
access()
|
||
--------
|
||
|
||
::
|
||
|
||
int access(address const& addr) const;
|
||
|
||
Returns the access permissions for the given address (``addr``). The permission
|
||
can currently be 0 or ``ip_filter::blocked``. The complexity of this operation
|
||
is O(``log`` n), where n is the minimum number of non-overlapping ranges to describe
|
||
the current filter.
|
||
|
||
|
||
export_filter()
|
||
---------------
|
||
|
||
::
|
||
|
||
boost::tuple<std::vector<ip_range<address_v4> >
|
||
, std::vector<ip_range<address_v6> > > export_filter() const;
|
||
|
||
This function will return the current state of the filter in the minimum number of
|
||
ranges possible. They are sorted from ranges in low addresses to high addresses. Each
|
||
entry in the returned vector is a range with the access control specified in its
|
||
``flags`` field.
|
||
|
||
The return value is a tuple containing two range-lists. One for IPv4 addresses
|
||
and one for IPv6 addresses.
|
||
|
||
|
||
big_number
|
||
==========
|
||
|
||
Both the ``peer_id`` and ``sha1_hash`` types are typedefs of the class
|
||
``big_number``. It represents 20 bytes of data. Its synopsis follows::
|
||
|
||
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();
|
||
};
|
||
|
||
The iterators gives you access to individual bytes.
|
||
|
||
|
||
|
||
hasher
|
||
======
|
||
|
||
This class creates sha1-hashes. Its declaration looks like this::
|
||
|
||
class hasher
|
||
{
|
||
public:
|
||
hasher();
|
||
hasher(char const* data, unsigned int len);
|
||
|
||
void update(char const* data, unsigned int len);
|
||
sha1_hash final();
|
||
void reset();
|
||
};
|
||
|
||
|
||
You use it by first instantiating it, then call ``update()`` 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 ``final()`` and it
|
||
will return the sha1-hash of the data.
|
||
|
||
The constructor that takes a ``char const*`` and an integer will construct the
|
||
sha1 context and feed it the data passed in.
|
||
|
||
If you want to reuse the hasher object once you have created a hash, you have to
|
||
call ``reset()`` to reinitialize it.
|
||
|
||
The sha1-algorithm used was implemented by Steve Reid and released as public domain.
|
||
For more info, see ``src/sha1.cpp``.
|
||
|
||
|
||
fingerprint
|
||
===========
|
||
|
||
The fingerprint class represents information about a client and its version. It is used
|
||
to encode this information into the client's peer id.
|
||
|
||
This is the class declaration::
|
||
|
||
struct fingerprint
|
||
{
|
||
fingerprint(const char* id_string, int major, int minor
|
||
, int revision, int tag);
|
||
|
||
std::string to_string() const;
|
||
|
||
char name[2];
|
||
char major_version;
|
||
char minor_version;
|
||
char revision_version;
|
||
char tag_version;
|
||
|
||
};
|
||
|
||
The constructor takes a ``char const*`` that should point to a string constant containing
|
||
exactly two characters. These are the characters that should be unique for your client. Make
|
||
sure not to clash with anybody else. Here are some taken id's:
|
||
|
||
+----------+-----------------------+
|
||
| id chars | client |
|
||
+==========+=======================+
|
||
| 'AZ' | Azureus |
|
||
+----------+-----------------------+
|
||
| 'LT' | libtorrent (default) |
|
||
+----------+-----------------------+
|
||
| 'BX' | BittorrentX |
|
||
+----------+-----------------------+
|
||
| 'MT' | Moonlight Torrent |
|
||
+----------+-----------------------+
|
||
| 'TS' | Torrent Storm |
|
||
+----------+-----------------------+
|
||
| 'SS' | Swarm Scope |
|
||
+----------+-----------------------+
|
||
| 'XT' | Xan Torrent |
|
||
+----------+-----------------------+
|
||
|
||
There's currently an informal directory of client id's here__.
|
||
|
||
__ http://wiki.theory.org/BitTorrentSpecification#peer_id
|
||
|
||
|
||
The ``major``, ``minor``, ``revision`` and ``tag`` parameters are used to identify the
|
||
version of your client. All these numbers must be within the range [0, 9].
|
||
|
||
``to_string()`` will generate the actual string put in the peer-id, and return it.
|
||
|
||
|
||
free functions
|
||
==============
|
||
|
||
identify_client()
|
||
-----------------
|
||
|
||
::
|
||
|
||
std::string identify_client(peer_id const& id);
|
||
|
||
This function is declared in the header ``<libtorrent/identify_client.hpp>``. It can can be used
|
||
to extract a string describing a client version from its peer-id. It will recognize most clients
|
||
that have this kind of identification in the peer-id.
|
||
|
||
|
||
client_fingerprint()
|
||
--------------------
|
||
|
||
::
|
||
|
||
boost::optional<fingerprint> client_fingerprint(peer_id const& p);
|
||
|
||
Returns an optional fingerprint if any can be identified from the peer id. This can be used
|
||
to automate the identification of clients. It will not be able to identify peers with non-
|
||
standard encodings. Only Azureus style, Shadow's style and Mainline style. This function is
|
||
declared in the header ``<libtorrent/identify_client.hpp>``.
|
||
|
||
|
||
bdecode() bencode()
|
||
-------------------
|
||
|
||
::
|
||
|
||
template<class InIt> entry bdecode(InIt start, InIt end);
|
||
template<class OutIt> void bencode(OutIt out, const entry& e);
|
||
|
||
|
||
These functions will encode data to bencoded_ or decode bencoded_ data.
|
||
|
||
.. _bencoded: http://wiki.theory.org/index.php/BitTorrentSpecification
|
||
|
||
The entry_ class is the internal representation of the bencoded data
|
||
and it can be used to retrieve information, an entry_ can also be build by
|
||
the program and given to ``bencode()`` to encode it into the ``OutIt``
|
||
iterator.
|
||
|
||
The ``OutIt`` and ``InIt`` are iterators
|
||
(InputIterator_ and OutputIterator_ respectively). They
|
||
are templates and are usually instantiated as ostream_iterator_,
|
||
back_insert_iterator_ or istream_iterator_. These
|
||
functions will assume that the iterator refers to a character
|
||
(``char``). So, if you want to encode entry ``e`` into a buffer
|
||
in memory, you can do it like this::
|
||
|
||
std::vector<char> buffer;
|
||
bencode(std::back_inserter(buf), e);
|
||
|
||
.. _InputIterator: http://www.sgi.com/tech/stl/InputIterator.html
|
||
.. _OutputIterator: http://www.sgi.com/tech/stl/OutputIterator.html
|
||
.. _ostream_iterator: http://www.sgi.com/tech/stl/ostream_iterator.html
|
||
.. _back_insert_iterator: http://www.sgi.com/tech/stl/back_insert_iterator.html
|
||
.. _istream_iterator: http://www.sgi.com/tech/stl/istream_iterator.html
|
||
|
||
If you want to decode a torrent file from a buffer in memory, you can do it like this::
|
||
|
||
std::vector<char> buffer;
|
||
// ...
|
||
entry e = bdecode(buf.begin(), buf.end());
|
||
|
||
Or, if you have a raw char buffer::
|
||
|
||
const char* buf;
|
||
// ...
|
||
entry e = bdecode(buf, buf + data_size);
|
||
|
||
Now we just need to know how to retrieve information from the entry_.
|
||
|
||
If ``bdecode()`` encounters invalid encoded data in the range given to it
|
||
it will throw invalid_encoding_.
|
||
|
||
|
||
|
||
alerts
|
||
======
|
||
|
||
The ``pop_alert()`` function on session is the interface for retrieving
|
||
alerts, warnings, messages and errors from libtorrent. If there hasn't
|
||
occurred any errors (matching your severity level) ``pop_alert()`` will
|
||
return a zero pointer. If there has been some error, it will return a pointer
|
||
to an alert object describing it. You can then use the alert object and query
|
||
it for information about the error or message. To retrieve any alerts, you have
|
||
to select a severity level using ``session::set_severity_level()``. It defaults to
|
||
``alert::none``, which means that you don't get any messages at all, ever.
|
||
You have the following levels to select among:
|
||
|
||
+--------------+----------------------------------------------------------+
|
||
| ``none`` | No alert will ever have this severity level, which |
|
||
| | effectively filters all messages. |
|
||
| | |
|
||
+--------------+----------------------------------------------------------+
|
||
| ``fatal`` | Fatal errors will have this severity level. Examples can |
|
||
| | be disk full or something else that will make it |
|
||
| | impossible to continue normal execution. |
|
||
| | |
|
||
+--------------+----------------------------------------------------------+
|
||
| ``critical`` | Signals errors that requires user interaction or |
|
||
| | messages that almost never should be ignored. For |
|
||
| | example, a chat message received from another peer is |
|
||
| | announced as severity ``critical``. |
|
||
| | |
|
||
+--------------+----------------------------------------------------------+
|
||
| ``warning`` | Messages with the warning severity can be a tracker that |
|
||
| | times out or responds with invalid data. It will be |
|
||
| | retried automatically, and the possible next tracker in |
|
||
| | a multitracker sequence will be tried. It does not |
|
||
| | require any user interaction. |
|
||
| | |
|
||
+--------------+----------------------------------------------------------+
|
||
| ``info`` | Events that can be considered normal, but still deserves |
|
||
| | an event. This could be a piece hash that fails. |
|
||
| | |
|
||
+--------------+----------------------------------------------------------+
|
||
| ``debug`` | This will include a lot of debug events that can be used |
|
||
| | both for debugging libtorrent but also when debugging |
|
||
| | other clients that are connected to libtorrent. It will |
|
||
| | report strange behaviors among the connected peers. |
|
||
| | |
|
||
+--------------+----------------------------------------------------------+
|
||
|
||
When setting a severity level, you will receive messages of that severity and all
|
||
messages that are more sever. If you set ``alert::none`` (the default) you will not receive
|
||
any events at all.
|
||
|
||
When you set a severity level other than ``none``, you have the responsibility to call
|
||
``pop_alert()`` from time to time. If you don't do that, the alert queue will just grow.
|
||
|
||
When you get an alert, you can use ``typeid()`` or ``dynamic_cast<>`` to get more detailed
|
||
information on exactly which type it is. i.e. what kind of error it is. You can also use a
|
||
dispatcher_ mechanism that's available in libtorrent.
|
||
|
||
All alert types are defined in the ``<libtorrent/alert_types.hpp>`` header file.
|
||
|
||
The ``alert`` class is the base class that specific messages are derived from. This
|
||
is its synopsis::
|
||
|
||
class alert
|
||
{
|
||
public:
|
||
|
||
enum severity_t { debug, info, warning, critical, fatal, none };
|
||
|
||
alert(severity_t severity, std::string const& msg);
|
||
virtual ~alert();
|
||
|
||
std::string const& msg() const;
|
||
severity_t severity() const;
|
||
|
||
virtual std::auto_ptr<alert> clone() const = 0;
|
||
};
|
||
|
||
This means that all alerts have at least a string describing it. They also
|
||
have a severity level that can be used to sort them or present them to the
|
||
user in different ways.
|
||
|
||
There's another alert base class that all most alerts derives from, all the
|
||
alerts that are generated for a specific torrent are derived from::
|
||
|
||
struct torrent_alert: alert
|
||
{
|
||
torrent_alert(torrent_handle const& h, severity_t s, std::string const& msg);
|
||
|
||
torrent_handle handle;
|
||
};
|
||
|
||
The specific alerts, that all derives from ``alert``, are:
|
||
|
||
|
||
listen_failed_alert
|
||
-------------------
|
||
|
||
This alert is generated when none of the ports, given in the port range, to
|
||
session_ can be opened for listening. This alert is generated as severity
|
||
level ``fatal``.
|
||
|
||
::
|
||
|
||
struct listen_failed_alert: alert
|
||
{
|
||
listen_failed_alert(const std::string& msg);
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
};
|
||
|
||
|
||
file_error_alert
|
||
----------------
|
||
|
||
If the storage fails to read or write files that it needs access to, this alert is
|
||
generated and the torrent is paused. It is generated as severity level ``fatal``.
|
||
|
||
::
|
||
|
||
struct file_error_alert: torrent_alert
|
||
{
|
||
file_error_alert(
|
||
const torrent_handle& h
|
||
, const std::string& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
};
|
||
|
||
|
||
tracker_announce_alert
|
||
----------------------
|
||
|
||
This alert is generated each time a tracker announce is sent (or attempted to be sent).
|
||
It is generated at severity level ``info``.
|
||
|
||
::
|
||
|
||
struct tracker_announce_alert: torrent_alert
|
||
{
|
||
tracker_announce_alert(
|
||
const torrent_handle& h
|
||
, const std::string& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
};
|
||
|
||
|
||
tracker_alert
|
||
-------------
|
||
|
||
This alert is generated on tracker time outs, premature disconnects, invalid response or
|
||
a HTTP response other than "200 OK". From the alert you can get the handle to the torrent
|
||
the tracker belongs to. This alert is generated as severity level ``warning``.
|
||
|
||
The ``times_in_row`` member says how many times in a row this tracker has failed.
|
||
``status_code`` is the code returned from the HTTP server. 401 means the tracker needs
|
||
authentication, 404 means not found etc. If the tracker timed out, the code will be set
|
||
to 0.
|
||
|
||
::
|
||
|
||
struct tracker_alert: torrent_alert
|
||
{
|
||
tracker_alert(torrent_handle const& h, int times, int status
|
||
, const std::string& msg);
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
|
||
int times_in_row;
|
||
int status_code;
|
||
};
|
||
|
||
|
||
tracker_reply_alert
|
||
-------------------
|
||
|
||
This alert is only for informational purpose. It is generated when a tracker announce
|
||
succeeds. It is generated regardless what kind of tracker was used, be it UDP, HTTP or
|
||
the DHT. It is generated with severity level ``info``.
|
||
|
||
::
|
||
|
||
struct tracker_reply_alert: torrent_alert
|
||
{
|
||
tracker_reply_alert(const torrent_handle& h
|
||
, int num_peers
|
||
, const std::string& msg);
|
||
|
||
int num_peers;
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
};
|
||
|
||
The ``num_peers`` tells how many peers were returned from the tracker. This is
|
||
not necessarily all new peers, some of them may already be connected.
|
||
|
||
tracker_warning_alert
|
||
---------------------
|
||
|
||
This alert is triggered if the tracker reply contains a warning field. Usually this
|
||
means that the tracker announce was successful, but the tracker has a message to
|
||
the client. The message string in the alert will contain the warning message from
|
||
the tracker. It is generated with severity level ``warning``.
|
||
|
||
::
|
||
|
||
struct tracker_warning_alert: torrent_alert
|
||
{
|
||
tracker_warning_alert(torrent_handle const& h
|
||
, std::string const& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
};
|
||
|
||
|
||
url_seed_alert
|
||
--------------
|
||
|
||
This alert is generated when a HTTP seed name lookup fails. This alert is
|
||
generated as severity level ``warning``.
|
||
|
||
It contains ``url`` to the HTTP seed that failed along with an error message.
|
||
|
||
::
|
||
|
||
struct url_seed_alert: torrent_alert
|
||
{
|
||
url_seed_alert(torrent_handle const& h, std::string const& h
|
||
, const std::string& msg);
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
|
||
std::string url;
|
||
};
|
||
|
||
|
||
hash_failed_alert
|
||
-----------------
|
||
|
||
This alert is generated when a finished piece fails its hash check. You can get the handle
|
||
to the torrent which got the failed piece and the index of the piece itself from the alert.
|
||
This alert is generated as severity level ``info``.
|
||
|
||
::
|
||
|
||
struct hash_failed_alert: torrent_alert
|
||
{
|
||
hash_failed_alert(
|
||
torrent_handle const& h
|
||
, int index
|
||
, const std::string& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
|
||
int piece_index;
|
||
};
|
||
|
||
|
||
peer_ban_alert
|
||
--------------
|
||
|
||
This alert is generated when a peer is banned because it has sent too many corrupt pieces
|
||
to us. It is generated at severity level ``info``. The ``handle`` member is a torrent_handle_
|
||
to the torrent that this peer was a member of.
|
||
|
||
::
|
||
|
||
struct peer_ban_alert: torrent_alert
|
||
{
|
||
peer_ban_alert(
|
||
asio::ip::tcp::endpoint const& pip
|
||
, torrent_handle h
|
||
, const std::string& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
|
||
asio::ip::tcp::endpoint ip;
|
||
};
|
||
|
||
|
||
peer_error_alert
|
||
----------------
|
||
|
||
This alert is generated when a peer sends invalid data over the peer-peer protocol. The peer
|
||
will be disconnected, but you get its ip address from the alert, to identify it. This alert
|
||
is generated as severity level ``debug``.
|
||
|
||
::
|
||
|
||
struct peer_error_alert: alert
|
||
{
|
||
peer_error_alert(
|
||
asio::ip::tcp::endpoint const& pip
|
||
, peer_id const& pid
|
||
, const std::string& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
asio::ip::tcp::endpoint ip;
|
||
peer_id id;
|
||
};
|
||
|
||
|
||
invalid_request_alert
|
||
---------------------
|
||
|
||
This is a debug alert that is generated by an incoming invalid piece request. The ``handle``
|
||
is a handle to the torrent the peer is a member of. ``<EFBFBD>p`` is the address of the peer and the
|
||
``request`` is the actual incoming request from the peer. The alert is generated as severity level
|
||
``debug``.
|
||
|
||
::
|
||
|
||
struct invalid_request_alert: torrent_alert
|
||
{
|
||
invalid_request_alert(
|
||
peer_request const& r
|
||
, torrent_handle const& h
|
||
, asio::ip::tcp::endpoint const& send
|
||
, peer_id const& pid
|
||
, std::string const& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
|
||
asio::ip::tcp::endpoint ip;
|
||
peer_request request;
|
||
peer_id id;
|
||
};
|
||
|
||
|
||
struct peer_request
|
||
{
|
||
int piece;
|
||
int start;
|
||
int length;
|
||
bool operator==(peer_request const& r) const;
|
||
};
|
||
|
||
|
||
The ``peer_request`` contains the values the client sent in its ``request`` message. ``piece`` is
|
||
the index of the piece it want data from, ``start`` is the offset within the piece where the data
|
||
should be read, and ``length`` is the amount of data it wants.
|
||
|
||
torrent_finished_alert
|
||
----------------------
|
||
|
||
This alert is generated when a torrent switches from being a downloader to a seed.
|
||
It will only be generated once per torrent. It contains a torrent_handle to the
|
||
torrent in question. This alert is generated as severity level ``info``.
|
||
|
||
::
|
||
|
||
struct torrent_finished_alert:torrent_ alert
|
||
{
|
||
torrent_finished_alert(
|
||
const torrent_handle& h
|
||
, const std::string& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
};
|
||
|
||
|
||
metadata_failed_alert
|
||
---------------------
|
||
|
||
This alert is generated when the metadata has been completely received and the info-hash
|
||
failed to match it. i.e. the metadata that was received was corrupt. libtorrent will
|
||
automatically retry to fetch it in this case. This is only relevant when running a
|
||
torrent-less download, with the metadata extension provided by libtorrent.
|
||
It is generated at severity level ``info``.
|
||
|
||
::
|
||
|
||
struct metadata_failed_alert: torrent_alert
|
||
{
|
||
metadata_failed_alert(
|
||
torrent_handle const& h
|
||
, std::string const& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
};
|
||
|
||
|
||
metadata_received_alert
|
||
-----------------------
|
||
|
||
This alert is generated when the metadata has been completely received and the torrent
|
||
can start downloading. It is not generated on torrents that are started with metadata, but
|
||
only those that needs to download it from peers (when utilizing the libtorrent extension).
|
||
It is generated at severity level ``info``.
|
||
|
||
::
|
||
|
||
struct metadata_received_alert: torrent_alert
|
||
{
|
||
metadata_received_alert(
|
||
torrent_handle const_& h
|
||
, std::string const& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
};
|
||
|
||
|
||
fastresume_rejected_alert
|
||
-------------------------
|
||
|
||
This alert is generated when a fastresume file has been passed to ``add_torrent`` but the
|
||
files on disk did not match the fastresume file. The string explains the reason why the
|
||
resume file was rejected. It is generated at severity level ``warning``.
|
||
|
||
::
|
||
|
||
struct fastresume_rejected_alert: alert
|
||
{
|
||
fastresume_rejected_alert(torrent_handle const& h
|
||
, std::string const& msg);
|
||
|
||
virtual std::auto_ptr<alert> clone() const;
|
||
torrent_handle handle;
|
||
};
|
||
|
||
|
||
|
||
dispatcher
|
||
----------
|
||
|
||
*TODO: describe the dispatcher mechanism*
|
||
|
||
|
||
|
||
exceptions
|
||
==========
|
||
|
||
There are a number of exceptions that can be thrown from different places in libtorrent,
|
||
here's a complete list with description.
|
||
|
||
|
||
invalid_handle
|
||
--------------
|
||
|
||
This exception is thrown when querying information from a torrent_handle_ that hasn't
|
||
been initialized or that has become invalid.
|
||
|
||
::
|
||
|
||
struct invalid_handle: std::exception
|
||
{
|
||
const char* what() const throw();
|
||
};
|
||
|
||
|
||
duplicate_torrent
|
||
-----------------
|
||
|
||
This is thrown by `add_torrent()`_ if the torrent already has been added to
|
||
the session.
|
||
|
||
::
|
||
|
||
struct duplicate_torrent: std::exception
|
||
{
|
||
const char* what() const throw();
|
||
};
|
||
|
||
|
||
invalid_encoding
|
||
----------------
|
||
|
||
This is thrown by ``bdecode()`` if the input data is not a valid bencoding.
|
||
|
||
::
|
||
|
||
struct invalid_encoding: std::exception
|
||
{
|
||
const char* what() const throw();
|
||
};
|
||
|
||
|
||
type_error
|
||
----------
|
||
|
||
This is thrown from the accessors of ``entry`` if the data type of the ``entry`` doesn't
|
||
match the type you want to extract from it.
|
||
|
||
::
|
||
|
||
struct type_error: std::runtime_error
|
||
{
|
||
type_error(const char* error);
|
||
};
|
||
|
||
|
||
invalid_torrent_file
|
||
--------------------
|
||
|
||
This exception is thrown from the constructor of ``torrent_info`` if the given bencoded information
|
||
doesn't meet the requirements on what information has to be present in a torrent file.
|
||
|
||
::
|
||
|
||
struct invalid_torrent_file: std::exception
|
||
{
|
||
const char* what() const throw();
|
||
};
|
||
|
||
|
||
fast resume
|
||
===========
|
||
|
||
The fast resume mechanism is a way to remember which pieces are downloaded
|
||
and where they are put between sessions. You can generate fast resume data by
|
||
calling ``torrent_handle::write_resume_data()`` on torrent_handle_. You can
|
||
then save this data to disk and use it when resuming the torrent. libtorrent
|
||
will not check the piece hashes then, and rely on the information given in the
|
||
fast-resume data. The fast-resume data also contains information about which
|
||
blocks, in the unfinished pieces, were downloaded, so it will not have to
|
||
start from scratch on the partially downloaded pieces.
|
||
|
||
To use the fast-resume data you simply give it to `add_torrent()`_, and it
|
||
will skip the time consuming checks. It may have to do the checking anyway, if
|
||
the fast-resume data is corrupt or doesn't fit the storage for that torrent,
|
||
then it will not trust the fast-resume data and just do the checking.
|
||
|
||
file format
|
||
-----------
|
||
|
||
The file format is a bencoded dictionary containing the following fields:
|
||
|
||
+----------------------+--------------------------------------------------------------+
|
||
| ``file-format`` | string: "libtorrent resume file" |
|
||
| | |
|
||
+----------------------+--------------------------------------------------------------+
|
||
| ``file-version`` | integer: 1 |
|
||
| | |
|
||
+----------------------+--------------------------------------------------------------+
|
||
| ``info-hash`` | string, the info hash of the torrent this data is saved for. |
|
||
| | |
|
||
+----------------------+--------------------------------------------------------------+
|
||
| ``blocks per piece`` | integer, the number of blocks per piece. Must be: piece_size |
|
||
| | / (16 * 1024). Clamped to be within the range [1, 256]. It |
|
||
| | is the number of blocks per (normal sized) piece. Usually |
|
||
| | each block is 16 * 1024 bytes in size. But if piece size is |
|
||
| | greater than 4 megabytes, the block size will increase. |
|
||
| | |
|
||
+----------------------+--------------------------------------------------------------+
|
||
| ``slots`` | list of integers. The list maps slots to piece indices. It |
|
||
| | tells which piece is on which slot. If piece index is -2 it |
|
||
| | means it is free, that there's no piece there. If it is -1, |
|
||
| | means the slot isn't allocated on disk yet. The pieces have |
|
||
| | to meet the following requirement: |
|
||
| | |
|
||
| | If there's a slot at the position of the piece index, |
|
||
| | the piece must be located in that slot. |
|
||
| | |
|
||
+----------------------+--------------------------------------------------------------+
|
||
| ``peers`` | list of dictionaries. Each dictionary has the following |
|
||
| | layout: |
|
||
| | |
|
||
| | +----------+-----------------------------------------------+ |
|
||
| | | ``ip`` | string, the ip address of the peer. This is | |
|
||
| | | | not a binary representation of the ip | |
|
||
| | | | address, but the string representation. It | |
|
||
| | | | may be an IPv6 string or an IPv4 string. | |
|
||
| | +----------+-----------------------------------------------+ |
|
||
| | | ``port`` | integer, the listen port of the peer | |
|
||
| | +----------+-----------------------------------------------+ |
|
||
| | |
|
||
| | These are the local peers we were connected to when this |
|
||
| | fast-resume data was saved. |
|
||
| | |
|
||
+----------------------+--------------------------------------------------------------+
|
||
| ``unfinished`` | list of dictionaries. Each dictionary represents an |
|
||
| | piece, and has the following layout: |
|
||
| | |
|
||
| | +-------------+--------------------------------------------+ |
|
||
| | | ``piece`` | integer, the index of the piece this entry | |
|
||
| | | | refers to. | |
|
||
| | +-------------+--------------------------------------------+ |
|
||
| | | ``bitmask`` | string, a binary bitmask representing the | |
|
||
| | | | blocks that have been downloaded in this | |
|
||
| | | | piece. | |
|
||
| | +-------------+--------------------------------------------+ |
|
||
| | | ``adler32`` | The adler32 checksum of the data in the | |
|
||
| | | | blocks specified by ``bitmask``. | |
|
||
| | | | | |
|
||
| | +-------------+--------------------------------------------+ |
|
||
| | |
|
||
+----------------------+--------------------------------------------------------------+
|
||
| ``file sizes`` | list where each entry corresponds to a file in the file list |
|
||
| | in the metadata. Each entry has a list of two values, the |
|
||
| | first value is the size of the file in bytes, the second |
|
||
| | is the time stamp when the last time someone wrote to it. |
|
||
| | This information is used to compare with the files on disk. |
|
||
| | All the files must match exactly this information in order |
|
||
| | to consider the resume data as current. Otherwise a full |
|
||
| | re-check is issued. |
|
||
+----------------------+--------------------------------------------------------------+
|
||
|
||
threads
|
||
=======
|
||
|
||
libtorrent starts 2 or 3 threads.
|
||
|
||
* The first thread is the main thread that will sit
|
||
idle in a ``select()`` call most of the time. This thread runs the main loop
|
||
that will send and receive data on all connections.
|
||
|
||
* The second thread is a hash-check thread. Whenever a torrent is added it will
|
||
first be passed to this thread for checking the files that may already have been
|
||
downloaded. If there is any resume data this thread will make sure it is valid
|
||
and matches the files. Once the torrent has been checked, it is passed on to the
|
||
main thread that will start it. The hash-check thread has a queue of torrents,
|
||
it will only check one torrent at a time.
|
||
|
||
* The third thread is spawned by asio on systems that don't support
|
||
non-blocking host name resolution to simulate non-blocking behavior.
|
||
|
||
|
||
storage allocation
|
||
==================
|
||
|
||
There are two modes in which storage (files on disk) are allocated in libtorrent.
|
||
|
||
* The traditional *full allocation* mode, where the entire files are filled up with
|
||
zeros before anything is downloaded.
|
||
|
||
* And the *compact allocation* mode, where only files are allocated for actual
|
||
pieces that have been downloaded. This is the default allocation mode in libtorrent.
|
||
|
||
The allocation mode is selected when a torrent is started. It is passed as a boolean
|
||
argument to ``session::add_torrent()`` (see `add_torrent()`_). These two modes have
|
||
different drawbacks and benefits.
|
||
|
||
full allocation
|
||
---------------
|
||
|
||
When a torrent is started in full allocation mode, the checker thread (see threads_)
|
||
will make sure that the entire storage is allocated, and fill any gaps with zeros.
|
||
It will of course still check for existing pieces and fast resume data. The main
|
||
drawbacks of this mode are:
|
||
|
||
* It will take longer to start the torrent, since it will need to fill the files
|
||
with zeros. This delay is linearly dependent on the size of the download.
|
||
|
||
* The download will occupy unnecessary disk space between download sessions.
|
||
|
||
* Disk caches usually perform extremely poorly with random access to large files
|
||
and may slow down a download considerably.
|
||
|
||
The benefits of this mode are:
|
||
|
||
* Downloaded pieces are written directly to their final place in the files and the
|
||
total number of disk operations will be fewer and may also play nicer to
|
||
filesystems' file allocation, and reduce fragmentation.
|
||
|
||
* No risk of a download failing because of a full disk during download.
|
||
|
||
|
||
compact allocation
|
||
------------------
|
||
|
||
The compact allocation will only allocate as much storage as it needs to keep the
|
||
pieces downloaded so far. This means that pieces will be moved around to be placed
|
||
at their final position in the files while downloading (to make sure the completed
|
||
download has all its pieces in the correct place). So, the main drawbacks are:
|
||
|
||
* More disk operations while downloading since pieces are moved around.
|
||
|
||
* Potentially more fragmentation in the filesystem.
|
||
|
||
The benefits though, are:
|
||
|
||
* No startup delay, since the files doesn't need allocating.
|
||
|
||
* The download will not use unnecessary disk space.
|
||
|
||
* Disk caches perform much better than in full allocation and raises the download
|
||
speed limit imposed by the disk.
|
||
|
||
The algorithm that is used when allocating pieces and slots isn't very complicated.
|
||
For the interested, a description follows.
|
||
|
||
storing a piece:
|
||
|
||
1. let **A** be a newly downloaded piece, with index **n**.
|
||
2. let **s** be the number of slots allocated in the file we're
|
||
downloading to. (the number of pieces it has room for).
|
||
3. if **n** >= **s** then allocate a new slot and put the piece there.
|
||
4. if **n** < **s** then allocate a new slot, move the data at
|
||
slot **n** to the new slot and put **A** in slot **n**.
|
||
|
||
allocating a new slot:
|
||
|
||
1. if there's an unassigned slot (a slot that doesn't
|
||
contain any piece), return that slot index.
|
||
2. append the new slot at the end of the file (or find an unused slot).
|
||
3. let **i** be the index of newly allocated slot
|
||
4. if we have downloaded piece index **i** already (to slot **j**) then
|
||
|
||
1. move the data at slot **j** to slot **i**.
|
||
2. return slot index **j** as the newly allocated free slot.
|
||
|
||
5. return **i** as the newly allocated slot.
|
||
|
||
|
||
extensions
|
||
==========
|
||
|
||
These extensions all operates within the `extension protocol`__. The
|
||
name of the extension is the name used in the extension-list packets,
|
||
and the payload is the data in the extended message (not counting the
|
||
length-prefix, message-id nor extension-id).
|
||
|
||
__ extension_protocol.html
|
||
|
||
Note that since this protocol relies on one of the reserved bits in the
|
||
handshake, it may be incompatible with future versions of the mainline
|
||
bittorrent client.
|
||
|
||
These are the extensions that are currently implemented.
|
||
|
||
metadata from peers
|
||
-------------------
|
||
|
||
Extension name: "LT_metadata"
|
||
|
||
The point with this extension is that you don't have to distribute the
|
||
metadata (.torrent-file) separately. The metadata can be distributed
|
||
through the bittorrent swarm. The only thing you need to download such
|
||
a torrent is the tracker url and the info-hash of the torrent.
|
||
|
||
It works by assuming that the initial seeder has the metadata and that
|
||
the metadata will propagate through the network as more peers join.
|
||
|
||
There are three kinds of messages in the metadata extension. These packets
|
||
are put as payload to the extension message. The three packets are:
|
||
|
||
* request metadata
|
||
* metadata
|
||
* don't have metadata
|
||
|
||
request metadata:
|
||
|
||
+-----------+---------------+----------------------------------------+
|
||
| size | name | description |
|
||
+===========+===============+========================================+
|
||
| uint8_t | msg_type | Determines the kind of message this is |
|
||
| | | 0 means 'request metadata' |
|
||
+-----------+---------------+----------------------------------------+
|
||
| uint8_t | start | The start of the metadata block that |
|
||
| | | is requested. It is given in 256:ths |
|
||
| | | of the total size of the metadata, |
|
||
| | | since the requesting client don't know |
|
||
| | | the size of the metadata. |
|
||
+-----------+---------------+----------------------------------------+
|
||
| uint8_t | size | The size of the metadata block that is |
|
||
| | | requested. This is also given in |
|
||
| | | 256:ths of the total size of the |
|
||
| | | metadata. The size is given as size-1. |
|
||
| | | That means that if this field is set |
|
||
| | | 0, the request wants one 256:th of the |
|
||
| | | metadata. |
|
||
+-----------+---------------+----------------------------------------+
|
||
|
||
metadata:
|
||
|
||
+-----------+---------------+----------------------------------------+
|
||
| size | name | description |
|
||
+===========+===============+========================================+
|
||
| uint8_t | msg_type | 1 means 'metadata' |
|
||
+-----------+---------------+----------------------------------------+
|
||
| int32_t | total_size | The total size of the metadata, given |
|
||
| | | in number of bytes. |
|
||
+-----------+---------------+----------------------------------------+
|
||
| int32_t | offset | The offset of where the metadata block |
|
||
| | | in this message belongs in the final |
|
||
| | | metadata. This is given in bytes. |
|
||
+-----------+---------------+----------------------------------------+
|
||
| uint8_t[] | metadata | The actual metadata block. The size of |
|
||
| | | this part is given implicit by the |
|
||
| | | length prefix in the bittorrent |
|
||
| | | protocol packet. |
|
||
+-----------+---------------+----------------------------------------+
|
||
|
||
Don't have metadata:
|
||
|
||
+-----------+---------------+----------------------------------------+
|
||
| size | name | description |
|
||
+===========+===============+========================================+
|
||
| uint8_t | msg_type | 2 means 'I don't have metadata'. |
|
||
| | | This message is sent as a reply to a |
|
||
| | | metadata request if the the client |
|
||
| | | doesn't have any metadata. |
|
||
+-----------+---------------+----------------------------------------+
|
||
|
||
HTTP seeding
|
||
------------
|
||
|
||
The HTTP seed extension implements `this specification`__.
|
||
|
||
The libtorrent implementation assumes that, if the URL ends with a slash
|
||
('/'), the filename should be appended to it in order to request pieces from
|
||
that file. The way this works is that if the torrent is a single-file torrent,
|
||
only that filename is appended. If the torrent is a multi-file torrent, the
|
||
torrent's name '/' the file name is appended. This is the same directory
|
||
structure that libtorrent will download torrents into.
|
||
|
||
__ http://www.getright.com/seedtorrent.html
|
||
|
||
|
||
filename checks
|
||
===============
|
||
|
||
Boost.Filesystem will by default check all its paths to make sure they conform
|
||
to filename requirements on many platforms. If you don't want this check, you can
|
||
set it to either only check for native filesystem requirements or turn it off
|
||
altogether. You can use::
|
||
|
||
boost::filesystem::path::default_name_check(boost::filesystem::native);
|
||
|
||
for example. For more information, see the `Boost.Filesystem docs`__.
|
||
|
||
__ http://www.boost.org/libs/filesystem/doc/index.htm
|
||
|
||
|
||
acknowledgments
|
||
===============
|
||
|
||
Written by Arvid Norberg. Copyright |copy| 2003-2006
|
||
|
||
Contributions by Magnus Jonsson, Daniel Wallin and Cory Nelson
|
||
|
||
Lots of testing, suggestions and contributions by Massaroddel and Tianhao Qiu.
|
||
|
||
Big thanks to Michael Wojciechowski and Peter Koeleman for making the autotools
|
||
scripts.
|
||
|
||
Thanks to Reimond Retz for bugfixes, suggestions and testing
|
||
|
||
Thanks to `University of Ume<6D>`__ for providing development and test hardware.
|
||
|
||
Project is hosted by sourceforge.
|
||
|
||
|sf_logo|__
|
||
|
||
.. |copy| unicode:: 0xA9 .. copyright sign
|
||
__ http://www.cs.umu.se
|
||
.. |sf_logo| image:: http://sourceforge.net/sflogo.php?group_id=7994
|
||
__ http://sourceforge.net
|
||
|
||
|