struct torrent_handle { torrent_handle () noexcept = default; void add_piece (piece_index_t piece, char const* data, add_piece_flags_t flags = {}) const; void read_piece (piece_index_t piece) const; bool have_piece (piece_index_t piece) const; void get_peer_info (std::vector<peer_info>& v) const; torrent_status status (status_flags_t flags = status_flags_t::all()) const; void get_download_queue (std::vector<partial_piece_info>& queue) const; void clear_piece_deadlines () const; void reset_piece_deadline (piece_index_t index) const; void set_piece_deadline (piece_index_t index, int deadline, deadline_flags_t flags = {}) const; void file_progress (std::vector<std::int64_t>& progress, int flags = 0) const; std::vector<open_file_state> file_status () const; void clear_error () const; std::vector<announce_entry> trackers () const; void replace_trackers (std::vector<announce_entry> const&) const; void add_tracker (announce_entry const&) const; void add_url_seed (std::string const& url) const; void remove_url_seed (std::string const& url) const; std::set<std::string> url_seeds () const; void add_http_seed (std::string const& url) const; void remove_http_seed (std::string const& url) const; std::set<std::string> http_seeds () const; void add_extension ( std::function<std::shared_ptr<torrent_plugin>(torrent_handle const&, void*)> const& ext , void* userdata = nullptr); bool set_metadata (span<char const> metadata) const; bool is_valid () const; void pause (pause_flags_t flags = {}) const; void resume () const; void set_flags (torrent_flags_t flags) const; void set_flags (torrent_flags_t flags, torrent_flags_t mask) const; void unset_flags (torrent_flags_t flags) const; torrent_flags_t flags () const; void flush_cache () const; void force_recheck () const; void save_resume_data (resume_data_flags_t flags = {}) const; bool need_save_resume_data () const; queue_position_t queue_position () const; void queue_position_top () const; void queue_position_down () const; void queue_position_bottom () const; void queue_position_up () const; void queue_position_set (queue_position_t p) const; void set_ssl_certificate (std::string const& certificate , std::string const& private_key , std::string const& dh_params , std::string const& passphrase = ""); void set_ssl_certificate_buffer (std::string const& certificate , std::string const& private_key , std::string const& dh_params); storage_interface* get_storage_impl () const; std::shared_ptr<const torrent_info> torrent_file () const; void piece_availability (std::vector<int>& avail) const; download_priority_t piece_priority (piece_index_t index) const; void piece_priority (piece_index_t index, download_priority_t priority) const; void prioritize_pieces (std::vector<std::pair<piece_index_t, download_priority_t>> const& pieces) const; void prioritize_pieces (std::vector<download_priority_t> const& pieces) const; std::vector<download_priority_t> get_piece_priorities () const; std::vector<download_priority_t> get_file_priorities () const; download_priority_t file_priority (file_index_t index) const; void file_priority (file_index_t index, download_priority_t priority) const; void prioritize_files (std::vector<download_priority_t> const& files) const; void force_dht_announce () const; void force_reannounce (int seconds = 0, int tracker_index = -1, reannounce_flags_t = {}) const; void scrape_tracker (int idx = -1) const; int upload_limit () const; int download_limit () const; void set_upload_limit (int limit) const; void set_download_limit (int limit) const; void connect_peer (tcp::endpoint const& adr, peer_source_flags_t source = {} , pex_flags_t flags = pex_encryption | pex_utp | pex_holepunch) const; int max_uploads () const; void set_max_uploads (int max_uploads) const; int max_connections () const; void set_max_connections (int max_connections) const; void move_storage (std::string const& save_path , move_flags_t flags = move_flags_t::always_replace_files ) const; void rename_file (file_index_t index, std::string const& new_name) const; sha1_hash info_hash () const; bool operator!= (const torrent_handle& h) const; bool operator< (const torrent_handle& h) const; bool operator== (const torrent_handle& h) const; std::uint32_t id () const; std::shared_ptr<torrent> native_handle () const; enum file_progress_flags_t { piece_granularity, }; static constexpr add_piece_flags_t overwrite_existing = 0_bit; static constexpr status_flags_t query_distributed_copies = 0_bit; static constexpr status_flags_t query_accurate_download_counters = 1_bit; static constexpr status_flags_t query_last_seen_complete = 2_bit; static constexpr status_flags_t query_pieces = 3_bit; static constexpr status_flags_t query_verified_pieces = 4_bit; static constexpr status_flags_t query_torrent_file = 5_bit; static constexpr status_flags_t query_name = 6_bit; static constexpr status_flags_t query_save_path = 7_bit; static constexpr deadline_flags_t alert_when_available = 0_bit; static constexpr pause_flags_t graceful_pause = 0_bit; static constexpr pause_flags_t clear_disk_cache = 1_bit; static constexpr resume_data_flags_t flush_disk_cache = 0_bit; static constexpr resume_data_flags_t save_info_dict = 1_bit; static constexpr resume_data_flags_t only_if_modified = 2_bit; static constexpr reannounce_flags_t ignore_min_interval = 0_bit; };[report issue]
torrent_handle()
torrent_handle () noexcept = default;
constructs a torrent handle that does not refer to a torrent. i.e. is_valid() will return false.
[report issue]add_piece()
void add_piece (piece_index_t piece, char const* data, add_piece_flags_t flags = {}) const;
This function will write data to the storage as piece piece, as if it had been downloaded from a peer. data is expected to point to a buffer of as many bytes as the size of the specified piece. The data in the buffer is copied and passed on to the disk IO thread to be written at a later point.
By default, data that's already been downloaded is not overwritten by this buffer. If you trust this data to be correct (and pass the piece hash check) you may pass the overwrite_existing flag. This will instruct libtorrent to overwrite any data that may already have been downloaded with this data.
Since the data is written asynchronously, you may know that is passed or failed the hash check by waiting for piece_finished_alert or hash_failed_alert.
[report issue]read_piece()
void read_piece (piece_index_t piece) const;
This function starts an asynchronous read operation of the specified piece from this torrent. You must have completed the download of the specified piece before calling this function.
When the read operation is completed, it is passed back through an alert, read_piece_alert. Since this alert is a response to an explicit call, it will always be posted, regardless of the alert mask.
Note that if you read multiple pieces, the read operations are not guaranteed to finish in the same order as you initiated them.
[report issue]have_piece()
bool have_piece (piece_index_t piece) const;
Returns true if this piece has been completely downloaded and written to disk, and false otherwise.
[report issue]get_peer_info()
void get_peer_info (std::vector<peer_info>& v) const;
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 system_error exception. Each entry in the vector contains information about that particular peer. See peer_info.
[report issue]status()
torrent_status status (status_flags_t flags = status_flags_t::all()) const;
status() will return a structure with information about the status of this torrent. If the torrent_handle is invalid, it will throw system_error exception. See torrent_status. The flags argument filters what information is returned in the torrent_status. Some information in there is relatively expensive to calculate, and if you're not interested in it (and see performance issues), you can filter them out.
By default everything is included. The flags you can use to decide what to include are defined in this class.
[report issue]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. See partial_piece_info for the fields in the returned vector.
[report issue]clear_piece_deadlines() reset_piece_deadline() set_piece_deadline()
void clear_piece_deadlines () const; void reset_piece_deadline (piece_index_t index) const; void set_piece_deadline (piece_index_t index, int deadline, deadline_flags_t flags = {}) const;
This function sets or resets the deadline associated with a specific piece index (index). libtorrent will attempt to download this entire piece before the deadline expires. This is not necessarily possible, but pieces with a more recent deadline will always be prioritized over pieces with a deadline further ahead in time. The deadline (and flags) of a piece can be changed by calling this function again.
If the piece is already downloaded when this call is made, nothing happens, unless the alert_when_available flag is set, in which case it will have the same effect as calling read_piece() for index.
deadline is the number of milliseconds until this piece should be completed.
reset_piece_deadline removes the deadline from the piece. If it hasn't already been downloaded, it will no longer be considered a priority.
clear_piece_deadlines() removes deadlines on all pieces in the torrent. As if reset_piece_deadline() was called on all pieces.
[report issue]file_progress()
void file_progress (std::vector<std::int64_t>& progress, int flags = 0) const;
This function fills in the supplied vector with the number of bytes downloaded 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. Its complexity is O(n + mj). Where n is the number of files, m is the number of downloading pieces and j is the number of blocks in a piece.
The flags parameter can be used to specify the granularity of the file progress. If left at the default value of 0, the progress will be as accurate as possible, but also more expensive to calculate. If torrent_handle::piece_granularity is specified, the progress will be specified in piece granularity. i.e. only pieces that have been fully downloaded and passed the hash check count. When specifying piece granularity, the operation is a lot cheaper, since libtorrent already keeps track of this internally and no calculation is required.
[report issue]file_status()
std::vector<open_file_state> file_status () const;
This function returns a vector with status about files that are open for this torrent. Any file that is not open will not be reported in the vector, i.e. it's possible that the vector is empty when returning, if none of the files in the torrent are currently open.
See open_file_state
[report issue]clear_error()
void clear_error () const;
If the torrent is in an error state (i.e. torrent_status::error is non-empty), this will clear the error and start the torrent again.
[report issue]add_tracker() replace_trackers() trackers()
std::vector<announce_entry> trackers () const; void replace_trackers (std::vector<announce_entry> const&) const; void add_tracker (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(). See announce_entry.
add_tracker() will look if the specified tracker is already in the set. If it is, it doesn't do anything. If it's not in the current set of trackers, it will insert it in the tier specified in the announce_entry.
The updated set of trackers will be saved in the resume data, and when a torrent is started with resume data, the trackers from the resume data will replace the original ones.
[report issue]url_seeds() add_url_seed() remove_url_seed()
void add_url_seed (std::string const& url) const; void remove_url_seed (std::string const& url) const; std::set<std::string> url_seeds () const;
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. remove_url_seed() removes the given url if it exists already. url_seeds() return a set of the url seeds currently in this torrent. Note that URLs that fails may be removed automatically from the list.
See http seeding for more information.
[report issue]http_seeds() remove_http_seed() add_http_seed()
void add_http_seed (std::string const& url) const; void remove_http_seed (std::string const& url) const; std::set<std::string> http_seeds () const;
These functions are identical as the *_url_seed() variants, but they operate on BEP 17 web seeds instead of BEP 19.
See http seeding for more information.
[report issue]add_extension()
void add_extension ( std::function<std::shared_ptr<torrent_plugin>(torrent_handle const&, void*)> const& ext , void* userdata = nullptr);
add the specified extension to this torrent. The ext argument is a function that will be called from within libtorrent's context passing in the internal torrent object and the specified userdata pointer. The function is expected to return a shared pointer to a torrent_plugin instance.
[report issue]set_metadata()
bool set_metadata (span<char const> metadata) const;
set_metadata expects the info section of metadata. i.e. The buffer passed in will be hashed and verified against the info-hash. If it fails, a metadata_failed_alert will be generated. If it passes, a metadata_received_alert is generated. The function returns true if the metadata is successfully set on the torrent, and false otherwise. If the torrent already has metadata, this function will not affect the torrent, and false will be returned.
[report issue]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.
[report issue]pause() resume()
void pause (pause_flags_t flags = {}) const; void resume () 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. Torrents may be paused automatically if there is a file error (e.g. disk full) or something similar. See file_error_alert.
To know if a torrent is paused or not, call torrent_handle::status() and inspect torrent_status::paused.
Note
Torrents that are auto-managed may be automatically resumed again. It does not make sense to pause an auto-managed torrent without making it not auto-managed first. Torrents are auto-managed by default when added to the session. For more information, see queuing.
unset_flags() set_flags() flags()
void set_flags (torrent_flags_t flags) const; void set_flags (torrent_flags_t flags, torrent_flags_t mask) const; void unset_flags (torrent_flags_t flags) const; torrent_flags_t flags () const;
sets and gets the torrent state flags. See torrent_flags_t. The set_flags overload that take a mask will affect all flags part of the mask, and set their values to what the flags argument is set to. This allows clearing and setting flags in a single function call. The set_flags overload that just takes flags, sets all the specified flags and leave any other flags unchanged. unset_flags clears the specified flags, while leaving any other flags unchanged.
The seed_mode flag is special, it can only be cleared by the set_flags() function, not set.
[report issue]flush_cache()
void flush_cache () const;
Instructs libtorrent to flush all the disk caches for this torrent and close all file handles. This is done asynchronously and you will be notified that it's complete through cache_flushed_alert.
Note that by the time you get the alert, libtorrent may have cached more data for the torrent, but you are guaranteed that whatever cached data libtorrent had by the time you called torrent_handle::flush_cache() has been written to disk.
[report issue]force_recheck()
void force_recheck () const;
force_recheck puts the torrent back in a state where it assumes to have no resume data. All peers will be disconnected and the torrent will stop announcing to the tracker. The torrent will be added to the checking queue, and will be checked (all the files will be read and compared to the piece hashes). Once the check is complete, the torrent will start connecting to peers again, as normal.
[report issue]save_resume_data()
void save_resume_data (resume_data_flags_t flags = {}) const;
save_resume_data() asks libtorrent to generate fast-resume data for this torrent.
This operation is asynchronous, save_resume_data will return immediately. The resume data is delivered when it's done through an save_resume_data_alert.
The fast resume data will be empty in the following cases:
- The torrent handle is invalid.
- The torrent hasn't received valid metadata and was started without metadata (see libtorrent's metadata from peers extension)
Note that by the time you receive the fast resume data, it may already be invalid if the torrent is still downloading! The recommended practice is to first pause the session, then generate the fast resume data, and then close it down. Make sure to not remove_torrent() before you receive the save_resume_data_alert though. There's no need to pause when saving intermittent resume data.
Warning
If you pause every torrent individually instead of pausing the session, every torrent will have its paused state saved in the resume data!
Warning
The resume data contains the modification timestamps for all files. If one file has been modified when the torrent is added again, the will be rechecked. When shutting down, make sure to flush the disk cache before saving the resume data. This will make sure that the file timestamps are up to date and won't be modified after saving the resume data. The recommended way to do this is to pause the torrent, which will flush the cache and disconnect all peers.
Note
It is typically a good idea to save resume data whenever a torrent is completed or paused. In those cases you don't need to pause the torrent or the session, since the torrent will do no more writing to its files. If you save resume data for torrents when they are paused, you can accelerate the shutdown process by not saving resume data again for paused torrents. Completed torrents should have their resume data saved when they complete and on exit, since their statistics might be updated.
In full allocation mode the resume data is never invalidated by subsequent writes to the files, since pieces won't move around. This means that you don't need to pause before writing resume data in full or sparse mode. If you don't, however, any data written to disk after you saved resume data and before the session closed is lost.
It also means that if the resume data is out dated, libtorrent will not re-check the files, but assume that it is fairly recent. The assumption is that it's better to loose a little bit than to re-check the entire file.
It is still a good idea to save resume data periodically during download as well as when closing down.
Example code to pause and save resume data for all torrents and wait for the alerts:
extern int outstanding_resume_data; // global counter of outstanding resume data std::vector<torrent_handle> handles = ses.get_torrents(); ses.pause(); for (torrent_handle const& h : handles) { if (!h.is_valid()) continue; torrent_status s = h.status(); if (!s.has_metadata || !s.need_save_resume_data()) continue; h.save_resume_data(); ++outstanding_resume_data; } while (outstanding_resume_data > 0) { alert const* a = ses.wait_for_alert(seconds(10)); // if we don't get an alert within 10 seconds, abort if (a == nullptr) break; std::vector<alert*> alerts; ses.pop_alerts(&alerts); for (alert* i : alerts) { if (alert_cast<save_resume_data_failed_alert>(a)) { process_alert(a); --outstanding_resume_data; continue; } save_resume_data_alert const* rd = alert_cast<save_resume_data_alert>(a); if (rd == nullptr) { process_alert(a); continue; } torrent_handle h = rd->handle; torrent_status st = h.status(torrent_handle::query_save_path | torrent_handle::query_name); std::ofstream out((st.save_path + "/" + st.name + ".fastresume").c_str() , std::ios_base::binary); std::vector<char> buf = write_resume_data_buf(rd->params); out.write(buf.data(), buf.size()); --outstanding_resume_data; } }
Note
Note how outstanding_resume_data is a global counter in this example. This is deliberate, otherwise there is a race condition for torrents that was just asked to save their resume data, they posted the alert, but it has not been received yet. Those torrents would report that they don't need to save resume data again, and skipped by the initial loop, and thwart the counter otherwise.
need_save_resume_data()
bool need_save_resume_data () const;
This function returns true if any whole chunk has been downloaded since the torrent was first loaded or since the last time the resume data was saved. When saving resume data periodically, it makes sense to skip any torrent which hasn't downloaded anything since the last time.
Note
A torrent's resume data is considered saved as soon as the save_resume_data_alert is posted. It is important to make sure this alert is received and handled in order for this function to be meaningful.
queue_position() queue_position_up() queue_position_bottom() queue_position_down() queue_position_top()
queue_position_t queue_position () const; void queue_position_top () const; void queue_position_down () const; void queue_position_bottom () const; void queue_position_up () const;
Every torrent that is added is assigned a queue position exactly one greater than the greatest queue position of all existing torrents. Torrents that are being seeded have -1 as their queue position, since they're no longer in line to be downloaded.
When a torrent is removed or turns into a seed, all torrents with greater queue positions have their positions decreased to fill in the space in the sequence.
queue_position() returns the torrent's position in the download queue. The torrents with the smallest numbers are the ones that are being downloaded. The smaller number, the closer the torrent is to the front of the line to be started.
The queue position is also available in the torrent_status.
The queue_position_*() functions adjust the torrents position in the queue. Up means closer to the front and down means closer to the back of the queue. Top and bottom refers to the front and the back of the queue respectively.
[report issue]queue_position_set()
void queue_position_set (queue_position_t p) const;
updates the position in the queue for this torrent. The relative order of all other torrents remain intact but their numerical queue position shifts to make space for this torrent's new position
[report issue]set_ssl_certificate_buffer() set_ssl_certificate()
void set_ssl_certificate (std::string const& certificate , std::string const& private_key , std::string const& dh_params , std::string const& passphrase = ""); void set_ssl_certificate_buffer (std::string const& certificate , std::string const& private_key , std::string const& dh_params);
For SSL torrents, use this to specify a path to a .pem file to use as this client's certificate. The certificate must be signed by the certificate in the .torrent file to be valid.
The set_ssl_certificate_buffer() overload takes the actual certificate, private key and DH params as strings, rather than paths to files.
cert is a path to the (signed) certificate in .pem format corresponding to this torrent.
private_key is a path to the private key for the specified certificate. This must be in .pem format.
dh_params is a path to the Diffie-Hellman parameter file, which needs to be in .pem format. You can generate this file using the openssl command like this: openssl dhparam -outform PEM -out dhparams.pem 512.
passphrase may be specified if the private key is encrypted and requires a passphrase to be decrypted.
Note that when a torrent first starts up, and it needs a certificate, it will suspend connecting to any peers until it has one. It's typically desirable to resume the torrent after setting the SSL certificate.
If you receive a torrent_need_cert_alert, you need to call this to provide a valid cert. If you don't have a cert you won't be allowed to connect to any peers.
[report issue]get_storage_impl()
storage_interface* get_storage_impl () const;
Returns the storage implementation for this torrent. This depends on the storage constructor function that was passed to add_torrent.
[report issue]torrent_file()
std::shared_ptr<const torrent_info> torrent_file () const;
Returns a pointer to the torrent_info object associated with this torrent. The torrent_info object may be a copy of the internal object. If the torrent doesn't have metadata, the pointer will not be initialized (i.e. a nullptr). The torrent may be in a state without metadata only if it was started without a .torrent file, e.g. by being added by magnet link
[report issue]piece_availability()
void piece_availability (std::vector<int>& avail) const;
Fills the specified std::vector<int> with the availability for each piece in this torrent. libtorrent does not keep track of availability for seeds, so if the torrent is seeding the availability for all pieces is reported as 0.
The piece availability is the number of peers that we are connected that has advertised having a particular piece. This is the information that libtorrent uses in order to prefer picking rare pieces.
[report issue]piece_priority() prioritize_pieces() get_piece_priorities()
download_priority_t piece_priority (piece_index_t index) const; void piece_priority (piece_index_t index, download_priority_t priority) const; void prioritize_pieces (std::vector<std::pair<piece_index_t, download_priority_t>> const& pieces) const; void prioritize_pieces (std::vector<download_priority_t> const& pieces) const; std::vector<download_priority_t> get_piece_priorities () const;
These functions are used to set and get the priority of individual pieces. By default all pieces have priority 4. That means that the random rarest first algorithm is effectively active for all pieces. You may however change the priority of individual pieces. There are 8 priority levels. 0 means not to download the piece at all. Otherwise, lower priority values means less likely to be picked. Piece priority takes precedence over piece availability. Every piece with priority 7 will be attempted to be picked before a priority 6 piece and so on.
The default priority of pieces is 4.
Piece priorities can not be changed for torrents that have not downloaded the metadata yet. Magnet links won't have metadata immediately. see the metadata_received_alert.
piece_priority sets or gets the priority for an individual piece, specified by index.
prioritize_pieces takes a vector of integers, one integer per piece in the torrent. All the piece priorities will be updated with the priorities in the vector. The second overload of prioritize_pieces that takes a vector of pairs will update the priorities of only select pieces, and leave all other unaffected. Each pair is (piece, priority). That is, the first item is the piece index and the second item is the priority of that piece. Invalid entries, where the piece index or priority is out of range, are not allowed.
get_piece_priorities returns a vector with one element for each piece in the torrent. Each element is the current priority of that piece.
It's possible to cancel the effect of file priorities by setting the priorities for the affected pieces. Care has to be taken when mixing usage of file- and piece priorities.
[report issue]get_file_priorities() prioritize_files() file_priority()
std::vector<download_priority_t> get_file_priorities () const; download_priority_t file_priority (file_index_t index) const; void file_priority (file_index_t index, download_priority_t priority) const; void prioritize_files (std::vector<download_priority_t> const& files) const;
index must be in the range [0, number_of_files).
file_priority() queries or sets the priority of file index.
prioritize_files() takes a vector that has at as many elements as there are files in the torrent. Each entry is the priority of that file. The function sets the priorities of all the pieces in the torrent based on the vector.
get_file_priorities() returns a vector with the priorities of all files.
The priority values are the same as for piece_priority(). See download_priority_t.
Whenever a file priority is changed, all other piece priorities are reset to match the file priorities. In order to maintain special priorities for particular pieces, piece_priority() has to be called again for those pieces.
You cannot set the file priorities on a torrent that does not yet have metadata or a torrent that is a seed. file_priority(int, int) and prioritize_files() are both no-ops for such torrents.
Since changing file priorities may involve disk operations (of moving files in- and out of the part file), the internal accounting of file priorities happen asynchronously. i.e. setting file priorities and then immediately querying them may not yield the same priorities just set. However, the piece priorities are updated immediately.
when combining file- and piece priorities, the resume file will record both. When loading the resume data, the file priorities will be applied first, then the piece priorities.
[report issue]force_reannounce() force_dht_announce()
void force_dht_announce () const; void force_reannounce (int seconds = 0, int tracker_index = -1, reannounce_flags_t = {}) const;
force_reannounce() will force this torrent to do another tracker request, to receive new peers. The seconds argument specifies how many seconds from now to issue the tracker announces.
If the tracker's min_interval has not passed since the last announce, the forced announce will be scheduled to happen immediately as the min_interval expires. This is to honor trackers minimum re-announce interval settings.
The tracker_index argument specifies which tracker to re-announce. If set to -1 (which is the default), all trackers are re-announce.
The flags argument can be used to affect the re-announce. See ignore_min_interval.
force_dht_announce will announce the torrent to the DHT immediately.
[report issue]scrape_tracker()
void scrape_tracker (int idx = -1) const;
scrape_tracker() will send a scrape request to a tracker. By default (idx = -1) it will scrape the last working tracker. If idx is >= 0, the tracker with the specified index will scraped.
A scrape request queries the tracker for statistics such as total number of incomplete peers, complete peers, number of downloads etc.
This request will specifically update the num_complete and num_incomplete fields in the torrent_status struct once it completes. When it completes, it will generate a scrape_reply_alert. If it fails, it will generate a scrape_failed_alert.
[report issue]set_upload_limit() upload_limit() download_limit() set_download_limit()
int upload_limit () const; int download_limit () const; 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 (settings_pack::upload_rate_limit) will not override the global rate limit. The torrent can never upload more than the global rate limit.
upload_limit and download_limit will return the current limit setting, for upload and download, respectively.
Local peers are not rate limited by default. see peer classes.
[report issue]connect_peer()
void connect_peer (tcp::endpoint const& adr, peer_source_flags_t source = {} , pex_flags_t flags = pex_encryption | pex_utp | pex_holepunch) 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 system_error. The second (optional) argument will be bitwise ORed into the source mask of this peer. Typically this is one of the source flags in peer_info. i.e. tracker, pex, dht etc.
For possible values of flags, see pex_flags_t.
[report issue]max_uploads() set_max_uploads()
int max_uploads () const; void set_max_uploads (int max_uploads) 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. This defaults to infinite. The primary setting controlling this is the global unchoke slots limit, set by unchoke_slots_limit in settings_pack.
max_uploads() returns the current settings.
[report issue]max_connections() set_max_connections()
int max_connections () const; void set_max_connections (int max_connections) const;
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. There is also a global limit of the number of connections, set by connections_limit in settings_pack.
max_connections() returns the current settings.
[report issue]move_storage()
void move_storage (std::string const& save_path , move_flags_t flags = move_flags_t::always_replace_files ) const;
Moves the file(s) that this torrent are currently seeding from or downloading to. If the given save_path is not located on the same drive as the original save path, the files will be copied to the new drive and removed from their original location. This will block all other disk IO, and other torrents download and upload rates may drop while copying the file.
Since disk IO is performed in a separate thread, this operation is also asynchronous. Once the operation completes, the storage_moved_alert is generated, with the new path as the message. If the move fails for some reason, storage_moved_failed_alert is generated instead, containing the error message.
The flags argument determines the behavior of the copying/moving of the files in the torrent. see move_flags_t.
always_replace_files is the default and replaces any file that exist in both the source directory and the target directory.
fail_if_exist first check to see that none of the copy operations would cause an overwrite. If it would, it will fail. Otherwise it will proceed as if it was in always_replace_files mode. Note that there is an inherent race condition here. If the files in the target directory appear after the check but before the copy or move completes, they will be overwritten. When failing because of files already existing in the target path, the error of move_storage_failed_alert is set to boost::system::errc::file_exists.
The intention is that a client may use this as a probe, and if it fails, ask the user which mode to use. The client may then re-issue the move_storage call with one of the other modes.
dont_replace always keeps the existing file in the target directory, if there is one. The source files will still be removed in that case. Note that it won't automatically re-check files. If an incomplete torrent is moved into a directory with the complete files, pause, move, force-recheck and resume. Without the re-checking, the torrent will keep downloading and files in the new download directory will be overwritten.
Files that have been renamed to have absolute paths are not moved by this function. Keep in mind that files that don't belong to the torrent but are stored in the torrent's directory may be moved as well. This goes for files that have been renamed to absolute paths that still end up inside the save path.
[report issue]rename_file()
void rename_file (file_index_t index, std::string const& new_name) const;
Renames the file with the given index asynchronously. The rename operation is complete when either a file_renamed_alert or file_rename_failed_alert is posted.
[report issue]info_hash()
sha1_hash info_hash () const;
info_hash() returns the info-hash of the torrent. If this handle is to a torrent that hasn't loaded yet (for instance by being added) by a URL, the returned value is undefined.
[report issue]operator!=() operator<() operator==()
bool operator!= (const torrent_handle& h) const; bool operator< (const torrent_handle& h) const; bool operator== (const torrent_handle& h) const;
comparison operators. The order of the torrents is unspecified but stable.
[report issue]id()
std::uint32_t id () const;
returns a unique identifier for this torrent. It's not a dense index. It's not preserved across sessions.
[report issue]native_handle()
std::shared_ptr<torrent> native_handle () const;
This function is intended only for use by plugins and the alert dispatch function. This type does not have a stable ABI and should be relied on as little as possible. Accessing the handle returned by this function is not thread safe outside of libtorrent's internal thread (which is used to invoke plugin callbacks). The torrent class is not only eligible for changing ABI across minor versions of libtorrent, its layout is also dependent on build configuration. This adds additional requirements on a client to be built with the exact same build configuration as libtorrent itself. i.e. the TORRENT_ macros must match between libtorrent and the client builds.
[report issue]enum file_progress_flags_t
Declared in "libtorrent/torrent_handle.hpp"
| name | value | description |
|---|---|---|
| piece_granularity | 1 | only calculate file progress at piece granularity. This makes the file_progress() call cheaper and also only takes bytes that have passed the hash check into account, so progress cannot regress in this mode. |
- overwrite_existing
- instruct libtorrent to overwrite any data that may already have been downloaded with the data of the new piece being added.
- query_distributed_copies
- calculates distributed_copies, distributed_full_copies and distributed_fraction.
- query_accurate_download_counters
- includes partial downloaded blocks in total_done and total_wanted_done.
- query_last_seen_complete
- includes last_seen_complete.
- query_pieces
- populate the pieces field in torrent_status.
- query_verified_pieces
- includes verified_pieces (only applies to torrents in seed mode).
- query_torrent_file
- includes torrent_file, which is all the static information from the .torrent file.
- query_name
- includes name, the name of the torrent. This is either derived from the .torrent file, or from the &dn= magnet link argument or possibly some other source. If the name of the torrent is not known, this is an empty string.
- query_save_path
- includes save_path, the path to the directory the files of the torrent are saved to.
- alert_when_available
- used to ask libtorrent to send an alert once the piece has been downloaded, by passing alert_when_available. When set, the read_piece_alert alert will be delivered, with the piece data, when it's downloaded.
- graceful_pause clear_disk_cache
- will delay the disconnect of peers that we're still downloading outstanding requests from. The torrent will not accept any more requests and will disconnect all idle peers. As soon as a peer is done transferring the blocks that were requested from it, it is disconnected. This is a graceful shut down of the torrent in the sense that no downloaded bytes are wasted.
- flush_disk_cache
- the disk cache will be flushed before creating the resume data. This avoids a problem with file timestamps in the resume data in case the cache hasn't been flushed yet.
- save_info_dict
- the resume data will contain the metadata from the torrent file as well. This is default for any torrent that's added without a torrent file (such as a magnet link or a URL).
- only_if_modified
- if nothing significant has changed in the torrent since the last time resume data was saved, fail this attempt. Significant changes primarily include more data having been downloaded, file or piece priorities having changed etc. If the resume data doesn't need saving, a save_resume_data_failed_alert is posted with the error resume_data_not_modified.
- ignore_min_interval
- by default, force-reannounce will still honor the min-interval published by the tracker. If this flag is set, it will be ignored and the tracker is announced immediately.
cache_status
Declared in "libtorrent/disk_io_thread.hpp"
this struct holds a number of statistics counters relevant for the disk io thread and disk cache.
struct cache_status { cache_status (); std::vector<cached_piece_info> pieces; };[report issue]
web_seed_entry
Declared in "libtorrent/torrent_info.hpp"
the web_seed_entry holds information about a web seed (also known as URL seed or HTTP seed). It is essentially a URL with some state associated with it. For more information, see BEP 17 and BEP 19.
struct web_seed_entry { bool operator== (web_seed_entry const& e) const; bool operator< (web_seed_entry const& e) const; enum type_t { url_seed, http_seed, }; std::string url; std::string auth; headers_t extra_headers; std::uint8_t type; };[report issue]
operator==()
bool operator== (web_seed_entry const& e) const;
URL and type comparison
[report issue]operator<()
bool operator< (web_seed_entry const& e) const;
URL and type less-than comparison
[report issue]enum type_t
Declared in "libtorrent/torrent_info.hpp"
| name | value | description |
|---|---|---|
| url_seed | 0 | |
| http_seed | 1 |
- url
- The URL of the web seed
- auth
- Optional authentication. If this is set, it's passed in as HTTP basic auth to the web seed. The format is: username:password.
- extra_headers
- Any extra HTTP headers that need to be passed to the web seed
- type
- The type of web seed (see type_t)
torrent_info
Declared in "libtorrent/torrent_info.hpp"
the torrent_info class holds the information found in a .torrent file.
class torrent_info { explicit torrent_info (bdecode_node const& torrent_file); torrent_info (char const* buffer, int size, error_code& ec); explicit torrent_info (sha1_hash const& info_hash); explicit torrent_info (std::string const& filename); torrent_info (bdecode_node const& torrent_file, error_code& ec); explicit torrent_info (span<char const> buffer, from_span_t); torrent_info (std::string const& filename, error_code& ec); torrent_info (span<char const> buffer, error_code& ec, from_span_t); torrent_info (bdecode_node const& torrent_file, load_torrent_limits const& cfg); torrent_info (span<char const> buffer, load_torrent_limits const& cfg, from_span_t); torrent_info (char const* buffer, int size); torrent_info (std::string const& filename, load_torrent_limits const& cfg); torrent_info (torrent_info const& t); ~torrent_info (); file_storage const& files () const; file_storage const& orig_files () const; void rename_file (file_index_t index, std::string const& new_filename); void remap_files (file_storage const& f); void add_tracker (std::string const& url, int tier , announce_entry::tracker_source source); std::vector<announce_entry> const& trackers () const; void add_tracker (std::string const& url, int tier = 0); std::vector<sha1_hash> similar_torrents () const; std::vector<std::string> collections () const; void add_url_seed (std::string const& url , std::string const& extern_auth = std::string() , web_seed_entry::headers_t const& extra_headers = web_seed_entry::headers_t()); std::vector<web_seed_entry> const& web_seeds () const; void set_web_seeds (std::vector<web_seed_entry> seeds); void add_http_seed (std::string const& url , std::string const& extern_auth = std::string() , web_seed_entry::headers_t const& extra_headers = web_seed_entry::headers_t()); std::int64_t total_size () const; int num_pieces () const; int piece_length () const; piece_index_t last_piece () const; index_range<piece_index_t> piece_range () const; piece_index_t end_piece () const; const sha1_hash& info_hash () const; int num_files () const; std::vector<file_slice> map_block (piece_index_t const piece , std::int64_t offset, int size) const; peer_request map_file (file_index_t const file, std::int64_t offset, int size) const; string_view ssl_cert () const; bool is_valid () const; bool priv () const; bool is_i2p () const; int piece_size (piece_index_t index) const; char const* hash_for_piece_ptr (piece_index_t const index) const; sha1_hash hash_for_piece (piece_index_t index) const; bool is_loaded () const; std::vector<sha1_hash> const& merkle_tree () const; void set_merkle_tree (std::vector<sha1_hash>& h); const std::string& name () const; std::time_t creation_date () const; const std::string& creator () const; const std::string& comment () const; std::vector<std::pair<std::string, int>> const& nodes () const; void add_node (std::pair<std::string, int> const& node); bool parse_info_section (bdecode_node const& e, error_code& ec); bool parse_info_section (bdecode_node const& e, error_code& ec, int piece_limit); bdecode_node info (char const* key) const; void swap (torrent_info& ti); int metadata_size () const; boost::shared_array<char> metadata () const; bool is_merkle_torrent () const; };[report issue]
torrent_info()
explicit torrent_info (bdecode_node const& torrent_file); torrent_info (char const* buffer, int size, error_code& ec); explicit torrent_info (sha1_hash const& info_hash); explicit torrent_info (std::string const& filename); torrent_info (bdecode_node const& torrent_file, error_code& ec); explicit torrent_info (span<char const> buffer, from_span_t); torrent_info (std::string const& filename, error_code& ec); torrent_info (span<char const> buffer, error_code& ec, from_span_t); torrent_info (bdecode_node const& torrent_file, load_torrent_limits const& cfg); torrent_info (span<char const> buffer, load_torrent_limits const& cfg, from_span_t); torrent_info (char const* buffer, int size); torrent_info (std::string const& filename, load_torrent_limits const& cfg); torrent_info (torrent_info const& t);
The constructor that takes an info-hash will initialize the info-hash to the given value, but leave all other fields empty. 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 constructor that takes a bdecode_node will create a torrent_info object from the information found in the given torrent_file. The bdecode_node represents a tree node in an bencoded file. To load an ordinary .torrent file into a bdecode_node, use bdecode().
The version that takes a buffer pointer and a size will decode it as a .torrent file and initialize the torrent_info object for you.
The version that takes a filename will simply load the torrent file and decode it inside the constructor, for convenience. This might not be the most suitable for applications that want to be able to report detailed errors on what might go wrong.
There is an upper limit on the size of the torrent file that will be loaded by the overload taking a filename. If it's important that even very large torrent files are loaded, use one of the other overloads.
The overloads that takes an error_code const& never throws if an error occur, they will simply set the error code to describe what went wrong and not fully initialize the torrent_info object. The overloads that do not take the extra error_code parameter will always throw if an error occurs. These overloads are not available when building without exception support.
The overload that takes a span also needs an extra parameter of type from_span_t to disambiguate the std::string overload for string literals. There is an object in the libtorrent namespace of this type called from_span.
[report issue]~torrent_info()
~torrent_info ();
frees all storage associated with this torrent_info object
[report issue]orig_files() files()
file_storage const& files () const; file_storage const& orig_files () const;
The file_storage object contains the information on how to map the pieces to files. It is separated from the torrent_info object because when creating torrents a storage object needs to be created without having a torrent file. When renaming files in a storage, the storage needs to make its own copy of the file_storage in order to make its mapping differ from the one in the torrent file.
orig_files() returns the original (unmodified) file storage for this torrent. This is used by the web server connection, which needs to request files with the original names. Filename may be changed using torrent_info::rename_file().
For more information on the file_storage object, see the separate document on how to create torrents.
[report issue]rename_file()
void rename_file (file_index_t index, std::string const& new_filename);
Renames a the file with the specified index to the new name. The new filename is reflected by the file_storage returned by files() but not by the one returned by orig_files().
If you want to rename the base name of the torrent (for a multi file torrent), you can copy the file_storage (see files() and orig_files() ), change the name, and then use remap_files().
The new_filename can both be a relative path, in which case the file name is relative to the save_path of the torrent. If the new_filename is an absolute path (i.e. is_complete(new_filename) == true), then the file is detached from the save_path of the torrent. In this case the file is not moved when move_storage() is invoked.
[report issue]remap_files()
void remap_files (file_storage const& f);
Remaps the file storage to a new file layout. This can be used to, for instance, download all data in a torrent to a single file, or to a number of fixed size sector aligned files, regardless of the number and sizes of the files in the torrent.
The new specified file_storage must have the exact same size as the current one.
[report issue]trackers() add_tracker()
void add_tracker (std::string const& url, int tier , announce_entry::tracker_source source); std::vector<announce_entry> const& trackers () const; void add_tracker (std::string const& url, int tier = 0);
add_tracker() adds a tracker to the announce-list. The tier determines the order in which the trackers are to be tried. 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. For more information, see announce_entry.
[report issue]collections() similar_torrents()
std::vector<sha1_hash> similar_torrents () const; std::vector<std::string> collections () const;
These two functions are related to BEP 38 (mutable torrents). The vectors returned from these correspond to the "similar" and "collections" keys in the .torrent file. Both info-hashes and collections from within the info-dict and from outside of it are included.
[report issue]add_url_seed() set_web_seeds() add_http_seed() web_seeds()
void add_url_seed (std::string const& url , std::string const& extern_auth = std::string() , web_seed_entry::headers_t const& extra_headers = web_seed_entry::headers_t()); std::vector<web_seed_entry> const& web_seeds () const; void set_web_seeds (std::vector<web_seed_entry> seeds); void add_http_seed (std::string const& url , std::string const& extern_auth = std::string() , web_seed_entry::headers_t const& extra_headers = web_seed_entry::headers_t());
web_seeds() returns all url seeds and http seeds in the torrent. Each entry is a web_seed_entry and may refer to either a url seed or http seed.
add_url_seed() and add_http_seed() adds one url to the list of url/http seeds. Currently, the only transport protocol supported for the url is http.
set_web_seeds() replaces all web seeds with the ones specified in the seeds vector.
The extern_auth argument can be used for other authorization schemes than basic HTTP authorization. If set, it will override any username and password found in the URL itself. The string will be sent as the HTTP authorization header's value (without specifying "Basic").
The extra_headers argument defaults to an empty list, but can be used to insert custom HTTP headers in the requests to a specific web seed.
See http seeding for more information.
[report issue]piece_length() num_pieces() total_size()
std::int64_t total_size () const; int num_pieces () const; int piece_length () 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.
[report issue]piece_range() last_piece() end_piece()
piece_index_t last_piece () const; index_range<piece_index_t> piece_range () const; piece_index_t end_piece () const;
last_piece() returns the index to the last piece in the torrent and end_piece() returns the index to the one-past-end piece in the torrent piece_range() returns an implementation-defined type that can be used as the container in a range-for loop. Where the values are the indices of all pieces in the file_storage.
[report issue]info_hash()
const sha1_hash& info_hash () const;
returns the info-hash of the torrent
[report issue]num_files()
int num_files () const;
If you need index-access to files you can use the num_files() along with the file_path(), file_size()-family of functions to access files using indices.
[report issue]map_block()
std::vector<file_slice> map_block (piece_index_t const piece , std::int64_t 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. See file_slice.
[report issue]map_file()
peer_request map_file (file_index_t const file, std::int64_t 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. See peer_request.
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().
[report issue]ssl_cert()
string_view ssl_cert () const;
Returns the SSL root certificate for the torrent, if it is an SSL torrent. Otherwise returns an empty string. The certificate is the public certificate in x509 format.
[report issue]is_valid()
bool is_valid () const;
returns true if this torrent_info object has a torrent loaded. This is primarily used to determine if a magnet link has had its metadata resolved yet or not.
[report issue]priv()
bool priv () const;
returns true if this torrent is private. i.e., the client should not advertise itself on the trackerless network (the Kademlia DHT) for this torrent.
[report issue]is_i2p()
bool is_i2p () const;
returns true if this is an i2p torrent. This is determined by whether or not it has a tracker whose URL domain name ends with ".i2p". i2p torrents disable the DHT and local peer discovery as well as talking to peers over anything other than the i2p network.
[report issue]piece_size()
int piece_size (piece_index_t index) const;
returns the piece size of file with index. This will be the same as piece_length(), except for the last piece, which may be shorter.
[report issue]hash_for_piece_ptr() hash_for_piece()
char const* hash_for_piece_ptr (piece_index_t const index) const; sha1_hash hash_for_piece (piece_index_t 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. hash_for_piece_ptr() returns a pointer to the 20 byte sha1 digest for the piece. Note that the string is not 0-terminated.
[report issue]set_merkle_tree() merkle_tree()
std::vector<sha1_hash> const& merkle_tree () const; void set_merkle_tree (std::vector<sha1_hash>& h);
merkle_tree() returns a reference to the merkle tree for this torrent, if any. set_merkle_tree() moves the passed in merkle tree into the torrent_info object. i.e. h will not be identical after the call. You need to set the merkle tree for a torrent that you've just created (as a merkle torrent). The merkle tree is retrieved from the create_torrent::merkle_tree() function, and need to be saved separately from the torrent file itself. Once it's added to libtorrent, the merkle tree will be persisted in the resume data.
[report issue]name()
const std::string& name () const;
name() returns the name of the torrent. name contains UTF-8 encoded string.
[report issue]creation_date()
std::time_t creation_date () const;
creation_date() returns the creation date of the torrent as time_t (posix time). If there's no time stamp in the torrent file, the optional object will be uninitialized. .. posix time: http://www.opengroup.org/onlinepubs/009695399/functions/time.html
[report issue]creator()
const std::string& creator () const;
creator() returns the creator string in the torrent. If there is no creator string it will return an empty string.
[report issue]comment()
const std::string& comment () const;
comment() returns the comment associated with the torrent. If there's no comment, it will return an empty string. comment contains UTF-8 encoded string.
[report issue]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).
[report issue]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.
[report issue]parse_info_section()
bool parse_info_section (bdecode_node const& e, error_code& ec); bool parse_info_section (bdecode_node const& e, error_code& ec, int piece_limit);
populates the torrent_info by providing just the info-dict buffer. This is used when loading a torrent from a magnet link for instance, where we only have the info-dict. The bdecode_node e points to a parsed info-dictionary. ec returns an error code if something fails (typically if the info dictionary is malformed). the piece_limit parameter allows limiting the amount of memory dedicated to loading the torrent, and fails for torrents that exceed the limit
[report issue]info()
bdecode_node info (char const* key) const;
This function looks up keys from the info-dictionary of the loaded torrent file. It can be used to access extension values put in the .torrent file. If the specified key cannot be found, it returns nullptr.
[report issue]metadata_size() metadata()
int metadata_size () const; boost::shared_array<char> metadata () const;
metadata() returns a the raw info section of the torrent file. The size of the metadata is returned by metadata_size().
[report issue]is_merkle_torrent()
bool is_merkle_torrent () const;
returns whether or not this is a merkle torrent. see BEP 30.
[report issue]add_torrent_params
Declared in "libtorrent/add_torrent_params.hpp"
The add_torrent_params is a parameter pack for adding torrents to a session. The key fields when adding a torrent are:
- ti - when you have loaded a .torrent file into a torrent_info object
- info_hash - when you don't have the metadata (.torrent file) but. This is set when adding a magnet link.
one of those fields must be set. Another mandatory field is save_path. The add_torrent_params object is passed into one of the session::add_torrent() overloads or session::async_add_torrent().
If you only specify the info-hash, the torrent file will be downloaded from peers, which requires them to support the metadata extension. For the metadata extension to work, libtorrent must be built with extensions enabled (TORRENT_DISABLE_EXTENSIONS must not be defined). It also takes an optional name argument. This may be left empty in case no name should be assigned to the torrent. In case it's not, the name is used for the torrent as long as it doesn't have metadata. See torrent_handle::name.
The add_torrent_params is also used when requesting resume data for a torrent. It can be saved to and restored from a file and added back to a new session. For serialization and de-serialization of add_torrent_params objects, see read_resume_data() and write_resume_data().
struct add_torrent_params { add_torrent_params (add_torrent_params&&) noexcept; add_torrent_params& operator= (add_torrent_params const&); explicit add_torrent_params (storage_constructor_type sc = default_storage_constructor); add_torrent_params& operator= (add_torrent_params&&) = default; add_torrent_params (add_torrent_params const&); int version = LIBTORRENT_VERSION_NUM; std::shared_ptr<torrent_info> ti; aux::noexcept_movable<std::vector<std::string>> trackers; aux::noexcept_movable<std::vector<int>> tracker_tiers; aux::noexcept_movable<std::vector<std::pair<std::string, int>>> dht_nodes; std::string name; std::string save_path; storage_mode_t storage_mode = storage_mode_sparse; aux::noexcept_movable<storage_constructor_type> storage; void* userdata = nullptr; aux::noexcept_movable<std::vector<download_priority_t>> file_priorities; std::string trackerid; torrent_flags_t flags = torrent_flags::default_flags; sha1_hash info_hash; int max_uploads = -1; int max_connections = -1; int upload_limit = -1; int download_limit = -1; std::int64_t total_uploaded = 0; std::int64_t total_downloaded = 0; int active_time = 0; int finished_time = 0; int seeding_time = 0; std::time_t added_time = 0; std::time_t completed_time = 0; std::time_t last_seen_complete = 0; int num_complete = -1; int num_incomplete = -1; int num_downloaded = -1; aux::noexcept_movable<std::vector<std::string>> http_seeds; aux::noexcept_movable<std::vector<std::string>> url_seeds; aux::noexcept_movable<std::vector<tcp::endpoint>> peers; aux::noexcept_movable<std::vector<tcp::endpoint>> banned_peers; aux::noexcept_movable<std::map<piece_index_t, bitfield>> unfinished_pieces; typed_bitfield<piece_index_t> have_pieces; typed_bitfield<piece_index_t> verified_pieces; aux::noexcept_movable<std::vector<download_priority_t>> piece_priorities; aux::noexcept_movable<std::vector<sha1_hash>> merkle_tree; aux::noexcept_movable<std::map<file_index_t, std::string>> renamed_files; std::time_t last_download = 0; std::time_t last_upload = 0; };[report issue]
add_torrent_params() operator=()
add_torrent_params (add_torrent_params&&) noexcept; add_torrent_params& operator= (add_torrent_params const&); explicit add_torrent_params (storage_constructor_type sc = default_storage_constructor); add_torrent_params& operator= (add_torrent_params&&) = default; add_torrent_params (add_torrent_params const&);
The constructor can be used to initialize the storage constructor, which determines the storage mechanism for the downloaded or seeding data for the torrent. For more information, see the storage field.
[report issue]- version
- filled in by the constructor and should be left untouched. It is used for forward binary compatibility.
- ti
- torrent_info object with the torrent to add. Unless the info_hash is set, this is required to be initialized.
- trackers
- If the torrent doesn't have a tracker, but relies on the DHT to find peers, the trackers can specify tracker URLs for the torrent.
- tracker_tiers
- the tiers the URLs in trackers belong to. Trackers belonging to different tiers may be treated differently, as defined by the multi tracker extension. This is optional, if not specified trackers are assumed to be part of tier 0, or whichever the last tier was as iterating over the trackers.
- dht_nodes
- a list of hostname and port pairs, representing DHT nodes to be added to the session (if DHT is enabled). The hostname may be an IP address.
- name
- in case there's no other name in this torrent, this name will be used. The name out of the torrent_info object takes precedence if available.
- save_path
the path where the torrent is or will be stored.
Note
On windows this path (and other paths) are interpreted as UNC paths. This means they must use backslashes as directory separators and may not contain the special directories "." or "..".
Setting this to an absolute path performs slightly better than a relative path.
- storage_mode
- One of the values from storage_mode_t. For more information, see storage allocation.
- storage
- can be used to customize how the data is stored. The default storage will simply write the data to the files it belongs to, but it could be overridden to save everything to a single file at a specific location or encrypt the content on disk for instance. For more information about the storage_interface that needs to be implemented for a custom storage, see storage_interface.
- userdata
- The userdata parameter is optional and will be passed on to the extension constructor functions, if any (see torrent_handle::add_extension()).
- file_priorities
- can be set to control the initial file priorities when adding a torrent. The semantics are the same as for torrent_handle::prioritize_files(). The file priorities specified in here take precedence over those specified in the resume data, if any.
- trackerid
- the default tracker id to be used when announcing to trackers. By default this is empty, and no tracker ID is used, since this is an optional argument. If a tracker returns a tracker ID, that ID is used instead of this.
- flags
flags controlling aspects of this torrent and how it's added. See torrent_flags_t for details.
Note
The flags field is initialized with default flags by the constructor. In order to preserve default behavior when clearing or setting other flags, make sure to bitwise OR or in a flag or bitwise AND the inverse of a flag to clear it.
- info_hash
- set this to the info hash of the torrent to add in case the info-hash is the only known property of the torrent. i.e. you don't have a .torrent file nor a magnet link. To add a magnet link, use parse_magnet_uri() to populate fields in the add_torrent_params object.
- max_uploads max_connections
max_uploads, max_connections, upload_limit, download_limit correspond to the set_max_uploads(), set_max_connections(), set_upload_limit() and set_download_limit() functions on torrent_handle. These values let you initialize these settings when the torrent is added, instead of calling these functions immediately following adding it.
-1 means unlimited on these settings just like their counterpart functions on torrent_handle
For fine grained control over rate limits, including making them apply to local peers, see peer classes.
- upload_limit download_limit
- the upload and download rate limits for this torrent, specified in bytes per second. -1 means unlimited.
- total_uploaded total_downloaded
- the total number of bytes uploaded and downloaded by this torrent so far.
- active_time finished_time seeding_time
- the number of seconds this torrent has spent in started, finished and seeding state so far, respectively.
- added_time completed_time
- if set to a non-zero value, this is the posix time of when this torrent was first added, including previous runs/sessions. If set to zero, the internal added_time will be set to the time of when add_torrent() is called.
- last_seen_complete
- if set to non-zero, initializes the time (expressed in posix time) when we last saw a seed or peers that together formed a complete copy of the torrent. If left set to zero, the internal counterpart to this field will be updated when we see a seed or a distributed copies >= 1.0.
- num_complete num_incomplete num_downloaded
these field can be used to initialize the torrent's cached scrape data. The scrape data is high level metadata about the current state of the swarm, as returned by the tracker (either when announcing to it or by sending a specific scrape request). num_complete is the number of peers in the swarm that are seeds, or have every piece in the torrent. num_incomplete is the number of peers in the swarm that do not have every piece. num_downloaded is the number of times the torrent has been downloaded (not initiated, but the number of times a download has completed).
Leaving any of these values set to -1 indicates we don't know, or we have not received any scrape data.
- http_seeds url_seeds
URLs can be added to these two lists to specify additional web seeds to be used by the torrent. If the flag_override_web_seeds is set, these will be the _only_ ones to be used. i.e. any web seeds found in the .torrent file will be overridden.
http_seeds expects URLs to web servers implementing the original HTTP seed specification BEP 17.
url_seeds expects URLs to regular web servers, aka "get right" style, specified in BEP 19.
- peers
- peers to add to the torrent, to be tried to be connected to as bittorrent peers.
- banned_peers
- peers banned from this torrent. The will not be connected to
- unfinished_pieces
- this is a map of partially downloaded piece. The key is the piece index and the value is a bitfield where each bit represents a 16 kiB block. A set bit means we have that block.
- have_pieces
- this is a bitfield indicating which pieces we already have of this torrent.
- verified_pieces
- when in seed_mode, pieces with a set bit in this bitfield have been verified to be valid. Other pieces will be verified the first time a peer requests it.
- piece_priorities
- this sets the priorities for each individual piece in the torrent. Each element in the vector represent the piece with the same index. If you set both file- and piece priorities, file priorities will take precedence.
- merkle_tree
- if this is a merkle tree torrent, and you're seeding, this field must be set. It is all the hashes in the binary tree, with the root as the first entry. See torrent_info::set_merkle_tree() for more info.
- renamed_files
- this is a map of file indices in the torrent and new filenames to be applied before the torrent is added.
- last_download last_upload
- the posix time of the last time payload was received or sent for this torrent, respectively.
peer_info
Declared in "libtorrent/peer_info.hpp"
holds information and statistics about one peer that libtorrent is connected to
struct peer_info { enum connection_type_t { standard_bittorrent, web_seed, http_seed, }; std::string client; typed_bitfield<piece_index_t> pieces; std::int64_t total_download; std::int64_t total_upload; time_duration last_request; time_duration last_active; time_duration download_queue_time; static constexpr peer_flags_t interesting = 0_bit; static constexpr peer_flags_t choked = 1_bit; static constexpr peer_flags_t remote_interested = 2_bit; static constexpr peer_flags_t remote_choked = 3_bit; static constexpr peer_flags_t supports_extensions = 4_bit; static constexpr peer_flags_t local_connection = 5_bit; static constexpr peer_flags_t handshake = 6_bit; static constexpr peer_flags_t connecting = 7_bit; static constexpr peer_flags_t on_parole = 9_bit; static constexpr peer_flags_t seed = 10_bit; static constexpr peer_flags_t optimistic_unchoke = 11_bit; static constexpr peer_flags_t snubbed = 12_bit; static constexpr peer_flags_t upload_only = 13_bit; static constexpr peer_flags_t endgame_mode = 14_bit; static constexpr peer_flags_t holepunched = 15_bit; static constexpr peer_flags_t i2p_socket = 16_bit; static constexpr peer_flags_t utp_socket = 17_bit; static constexpr peer_flags_t ssl_socket = 18_bit; static constexpr peer_flags_t rc4_encrypted = 19_bit; static constexpr peer_flags_t plaintext_encrypted = 20_bit; peer_flags_t flags; static constexpr peer_source_flags_t tracker = 0_bit; static constexpr peer_source_flags_t dht = 1_bit; static constexpr peer_source_flags_t pex = 2_bit; static constexpr peer_source_flags_t lsd = 3_bit; static constexpr peer_source_flags_t resume_data = 4_bit; static constexpr peer_source_flags_t incoming = 5_bit; peer_source_flags_t source; int up_speed; int down_speed; int payload_up_speed; int payload_down_speed; peer_id pid; int queue_bytes; int request_timeout; int send_buffer_size; int used_send_buffer; int receive_buffer_size; int used_receive_buffer; int receive_buffer_watermark; int num_hashfails; int download_queue_length; int timed_out_requests; int busy_requests; int requests_in_buffer; int target_dl_queue_length; int upload_queue_length; int failcount; piece_index_t downloading_piece_index; int downloading_block_index; int downloading_progress; int downloading_total; int connection_type; int pending_disk_bytes; int pending_disk_read_bytes; int send_quota; int receive_quota; int rtt; int num_pieces; int download_rate_peak; int upload_rate_peak; float progress; int progress_ppm; int deprecated_estimated_reciprocation_rate; tcp::endpoint ip; tcp::endpoint local_endpoint; static constexpr bandwidth_state_flags_t bw_idle = 0_bit; static constexpr bandwidth_state_flags_t bw_limit = 1_bit; static constexpr bandwidth_state_flags_t bw_network = 2_bit; static constexpr bandwidth_state_flags_t bw_disk = 4_bit; bandwidth_state_flags_t read_state; bandwidth_state_flags_t write_state; };[report issue]
enum connection_type_t
Declared in "libtorrent/peer_info.hpp"
| name | value | description |
|---|---|---|
| standard_bittorrent | 0 | Regular bittorrent connection |
| web_seed | 1 | HTTP connection using the BEP 19 protocol |
| http_seed | 2 | HTTP connection using the BEP 17 protocol |
- client
- 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.
- pieces
- a bitfield, with one bit per piece in the torrent. Each bit tells you if the peer has that piece (if it's set to 1) or if the peer miss that piece (set to 0).
- total_download total_upload
- 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.
- last_request last_active
- the time since we last sent a request to this peer and since any transfer occurred with this peer
- download_queue_time
- the time until all blocks in the request queue will be downloaded
- 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.
- supports_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).
- on_parole
- The peer has participated in a piece that failed the hash check, and is now "on parole", which means we're only requesting whole pieces from this peer until it either fails that piece or proves that it doesn't send bad data.
- seed
- This peer is a seed (it has all the pieces).
- optimistic_unchoke
- This peer is subject to an optimistic unchoke. It has been unchoked for a while to see if it might unchoke us in return an earn an upload/unchoke slot. If it doesn't within some period of time, it will be choked and another peer will be optimistically unchoked.
- snubbed
- This peer has recently failed to send a block within the request timeout from when the request was sent. We're currently picking one block at a time from this peer.
- upload_only
- This peer has either explicitly (with an extension) or implicitly (by becoming a seed) told us that it will not downloading anything more, regardless of which pieces we have.
- endgame_mode
- This means the last time this peer picket a piece, it could not pick as many as it wanted because there were not enough free ones. i.e. all pieces this peer has were already requested from other peers.
- holepunched
- This flag is set if the peer was in holepunch mode when the connection succeeded. This typically only happens if both peers are behind a NAT and the peers connect via the NAT holepunch mechanism.
- i2p_socket
- indicates that this socket is running on top of the I2P transport.
- utp_socket
- indicates that this socket is a uTP socket
- ssl_socket
- indicates that this socket is running on top of an SSL (TLS) channel
- rc4_encrypted
- this connection is obfuscated with RC4
- plaintext_encrypted
- the handshake of this connection was obfuscated with a Diffie-Hellman exchange
- flags
- tells you in which state the peer is in. It is set to any combination of the peer_flags_t flags above.
- tracker
- The peer was received from the tracker.
- dht
- The peer was received from the kademlia DHT.
- pex
- The peer was received from the peer exchange extension.
- lsd
- The peer was received from the local service discovery (The peer is on the local network).
- resume_data
- The peer was added from the fast resume data.
- incoming
- we received an incoming connection from this peer
- source
- a combination of flags describing from which sources this peer was received. A combination of the peer_source_flags_t above.
- up_speed down_speed
- the current upload and download speed we have to and from this peer (including any protocol messages). updated about once per second
- payload_up_speed payload_down_speed
- The transfer rates of payload data only updated about once per second
- pid
- 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()_
- queue_bytes
- the number of bytes we have requested from this peer, but not yet received.
- request_timeout
- the number of seconds until the current front piece request will time out. This timeout can be adjusted through settings_pack::request_timeout. -1 means that there is not outstanding request.
- send_buffer_size used_send_buffer
- the number of bytes allocated and used for the peer's send buffer, respectively.
- receive_buffer_size used_receive_buffer receive_buffer_watermark
- the number of bytes allocated and used as receive buffer, respectively.
- num_hashfails
- the number of pieces this peer has participated in sending us that turned out to fail the hash check.
- download_queue_length
- this is the number of requests we have sent to this peer that we haven't got a response for yet
- timed_out_requests
- the number of block requests that have timed out, and are still in the download queue
- busy_requests
- the number of busy requests in the download queue. A busy request is a request for a block we've also requested from a different peer
- requests_in_buffer
- the number of requests messages that are currently in the send buffer waiting to be sent.
- target_dl_queue_length
- the number of requests that is tried to be maintained (this is typically a function of download speed)
- upload_queue_length
- the number of piece-requests we have received from this peer that we haven't answered with a piece yet.
- failcount
- the number of times this peer has "failed". i.e. failed to connect or disconnected us. The failcount is decremented when we see this peer in a tracker response or peer exchange message.
- downloading_piece_index downloading_block_index downloading_progress downloading_total
- You can know which piece, and which part of that piece, that is currently being downloaded from a specific peer by looking at these 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.
- connection_type
- the kind of connection this peer uses. See connection_type_t.
- pending_disk_bytes
- the number of bytes this peer has pending in the disk-io thread. Downloaded and waiting to be written to disk. This is what is capped by settings_pack::max_queued_disk_bytes.
- pending_disk_read_bytes
- number of outstanding bytes to read from disk
- send_quota receive_quota
- the number of bytes this peer has been assigned to be allowed to send and receive until it has to request more quota from the bandwidth manager.
- rtt
- an estimated round trip time to this peer, in milliseconds. It is estimated by timing the TCP connect(). It may be 0 for incoming connections.
- num_pieces
- the number of pieces this peer has.
- download_rate_peak upload_rate_peak
- the highest download and upload rates seen on this connection. They are given in bytes per second. This number is reset to 0 on reconnect.
- progress
- the progress of the peer in the range [0, 1]. This is always 0 when floating point operations are disabled, instead use progress_ppm.
- progress_ppm
- indicates the download progress of the peer in the range [0, 1000000] (parts per million).
- ip
- the IP-address to this peer. The type is an asio endpoint. For more info, see the asio documentation.
- local_endpoint
- the IP and port pair the socket is bound to locally. i.e. the IP address of the interface it's going out over. This may be useful for multi-homed clients with multiple interfaces to the internet.
- bw_idle
- The peer is not waiting for any external events to send or receive data.
- bw_limit
- The peer is waiting for the rate limiter.
- bw_network
- The peer has quota and is currently waiting for a network read or write operation to complete. This is the state all peers are in if there are no bandwidth limits.
- bw_disk
- The peer is waiting for the disk I/O thread to catch up writing buffers to disk before downloading more.
- read_state write_state
- bitmasks indicating what state this peer is in with regards to sending and receiving data. The states are defined as independent flags of type bandwidth_state_flags_t, in this class.
peer_request
Declared in "libtorrent/peer_request.hpp"
represents a byte range within a piece. Internally this is is used for incoming piece requests.
struct peer_request { bool operator== (peer_request const& r) const; piece_index_t piece; int start; int length; };[report issue]
operator==()
bool operator== (peer_request const& r) const;
returns true if the right hand side peer_request refers to the same range as this does.
[report issue]- piece
- the index of the piece in which the range starts.
- start
- the offset within that piece where the range starts.
- length
- the size of the range, in bytes.
write_resume_data_buf() write_resume_data()
Declared in "libtorrent/write_resume_data.hpp"
entry write_resume_data (add_torrent_params const& atp); std::vector<char> write_resume_data_buf (add_torrent_params const& atp);
this function turns the resume data in an add_torrent_params object into a bencoded structure
[report issue]make_magnet_uri()
Declared in "libtorrent/magnet_uri.hpp"
std::string make_magnet_uri (torrent_handle const& handle); std::string make_magnet_uri (torrent_info const& info);
Generates a magnet URI from the specified torrent. If the torrent handle is invalid, an empty string is returned.
For more information about magnet links, see magnet links.
[report issue]parse_magnet_uri()
Declared in "libtorrent/magnet_uri.hpp"
void parse_magnet_uri (string_view uri, add_torrent_params& p, error_code& ec); add_torrent_params parse_magnet_uri (string_view uri); add_torrent_params parse_magnet_uri (string_view uri, error_code& ec);
This function parses out information from the magnet link and populates the add_torrent_params object. The overload that does not take an error_code reference will throw a system_error on error The overload taking an add_torrent_params reference will fill in the fields specified in the magnet URI.
[report issue]version()
Declared in "libtorrent/version.hpp"
char const* version ();
returns the libtorrent version as string form in this format: "<major>.<minor>.<tiny>.<tag>"
[report issue]generate_fingerprint()
Declared in "libtorrent/fingerprint.hpp"
std::string generate_fingerprint (std::string name , int major, int minor = 0, int revision = 0, int tag = 0);
This is a utility function to produce a client ID fingerprint formatted to the most common convention. The fingerprint can be set via the peer_fingerprint setting, in settings_pack.
The name string should contain exactly two characters. These are the characters unique to your client, used to identify it. Make sure not to clash with anybody else. Here are some taken id's:
| id chars | client |
|---|---|
| LT | libtorrent (default) |
| UT | uTorrent |
| UM | uTorrent Mac |
| qB | qBittorrent |
| BP | BitTorrent Pro |
| BT | BitTorrent |
| DE | Deluge |
| AZ | Azureus |
| TL | Tribler |
There's an informal directory of client id's here.
The major, minor, revision and tag parameters are used to identify the version of your client.
[report issue]hash_value()
Declared in "libtorrent/torrent_handle.hpp"
std::size_t hash_value (torrent_handle const& h);
for std::hash (and to support using this type in unordered_map etc.)
[report issue]is_utp_stream_logging()
Declared in "libtorrent/utp_stream.hpp"
bool is_utp_stream_logging ();[report issue]
set_utp_stream_logging()
Declared in "libtorrent/utp_stream.hpp"
void set_utp_stream_logging (bool enable);
This function should be used at the very beginning and very end of your program.
[report issue]read_resume_data()
Declared in "libtorrent/read_resume_data.hpp"
add_torrent_params read_resume_data (span<char const> buffer); add_torrent_params read_resume_data (bdecode_node const& rd , error_code& ec); add_torrent_params read_resume_data (bdecode_node const& rd); add_torrent_params read_resume_data (span<char const> buffer , error_code& ec);
these functions are used to parse resume data and populate the appropriate fields in an add_torrent_params object. This object can then be used to add the actual torrent_info object to and pass to session::add_torrent() or session::async_add_torrent().
If the client wants to override any field that was loaded from the resume data, e.g. save_path, those fields must be changed after loading resume data but before adding the torrent.
[report issue]enum connection_type
Declared in "libtorrent/peer_connection.hpp"
| name | value | description |
|---|---|---|
| bittorrent | 0 | |
| url_seed | 1 | |
| http_seed | 2 |
enum portmap_transport
Declared in "libtorrent/portmap.hpp"
| name | value | description |
|---|---|---|
| natpmp | 0 | natpmp can be NAT-PMP or PCP |
| upnp | 1 |
enum portmap_protocol
Declared in "libtorrent/portmap.hpp"
| name | value | description |
|---|---|---|
| none | 0 | |
| tcp | 1 | |
| udp | 2 |
file_open_mode_t
Declared in "libtorrent/disk_interface.hpp"
- read_only
- open the file for reading only
- write_only
- open the file for writing only
- read_write
- open the file for reading and writing
- rw_mask
- the mask for the bits determining read or write mode
- sparse
- open the file in sparse mode (if supported by the filesystem).
- no_atime
- don't update the access timestamps on the file (if supported by the operating system and filesystem). this generally improves disk performance.
- random_access
- open the file for random access. This disables read-ahead logic
open_mode_t
Declared in "libtorrent/file.hpp"
- read_only
- open the file for reading only
- write_only
- open the file for writing only
- read_write
- open the file for reading and writing
- rw_mask
- the mask for the bits making up the read-write mode.
- sparse
- open the file in sparse mode (if supported by the filesystem).
- no_atime
- don't update the access timestamps on the file (if supported by the operating system and filesystem). this generally improves disk performance.
- random_access
- open the file for random access. This disables read-ahead logic
- no_cache
- don't put any pressure on the OS disk cache because of access to this file. We expect our files to be fairly large, and there is already a cache at the bittorrent block level. This may improve overall system performance by leaving running applications in the page cache
- coalesce_buffers
- this is only used for readv/writev flags
- attribute_hidden
- when creating a file, set the hidden attribute (windows only)
- attribute_executable
- when creating a file, set the executable attribute
- attribute_mask
- the mask of all attribute bits
torrent_flags_t
Declared in "libtorrent/torrent_flags.hpp"
- seed_mode
If seed_mode is set, libtorrent will assume that all files are present for this torrent and that they all match the hashes in the torrent file. Each time a peer requests to download a block, the piece is verified against the hash, unless it has been verified already. If a hash fails, the torrent will automatically leave the seed mode and recheck all the files. The use case for this mode is if a torrent is created and seeded, or if the user already know that the files are complete, this is a way to avoid the initial file checks, and significantly reduce the startup time.
Setting seed_mode on a torrent without metadata (a .torrent file) is a no-op and will be ignored.
It is not possible to set the seed_mode flag on a torrent after it has been added to a session. It is possible to clear it though.
- upload_mode
If upload_mode is set, the torrent will be initialized in upload-mode, which means it will not make any piece requests. This state is typically entered on disk I/O errors, and if the torrent is also auto managed, it will be taken out of this state periodically (see settings_pack::optimistic_disk_retry).
This mode can be used to avoid race conditions when adjusting priorities of pieces before allowing the torrent to start downloading.
If the torrent is auto-managed (auto_managed), the torrent will eventually be taken out of upload-mode, regardless of how it got there. If it's important to manually control when the torrent leaves upload mode, don't make it auto managed.
- share_mode
determines if the torrent should be added in share mode or not. Share mode indicates that we are not interested in downloading the torrent, but merely want to improve our share ratio (i.e. increase it). A torrent started in share mode will do its best to never download more than it uploads to the swarm. If the swarm does not have enough demand for upload capacity, the torrent will not download anything. This mode is intended to be safe to add any number of torrents to, without manual screening, without the risk of downloading more than is uploaded.
A torrent in share mode sets the priority to all pieces to 0, except for the pieces that are downloaded, when pieces are decided to be downloaded. This affects the progress bar, which might be set to "100% finished" most of the time. Do not change file or piece priorities for torrents in share mode, it will make it not work.
The share mode has one setting, the share ratio target, see settings_pack::share_mode_target for more info.
- apply_ip_filter
- determines if the IP filter should apply to this torrent or not. By default all torrents are subject to filtering by the IP filter (i.e. this flag is set by default). This is useful if certain torrents needs to be exempt for some reason, being an auto-update torrent for instance.
- paused
- specifies whether or not the torrent is to be started in a paused state. I.e. it won't connect to the tracker or any of the peers until it's resumed. This is typically a good way of avoiding race conditions when setting configuration options on torrents before starting them.
- auto_managed
If the torrent is auto-managed (auto_managed), the torrent may be resumed at any point, regardless of how it paused. If it's important to manually control when the torrent is paused and resumed, don't make it auto managed.
If auto_managed is set, the torrent will be queued, started and seeded automatically by libtorrent. When this is set, the torrent should also be started as paused. The default queue order is the order the torrents were added. They are all downloaded in that order. For more details, see queuing.
- duplicate_is_error
- used in add_torrent_params to indicate that it's an error to attempt to add a torrent that's already in the session. If it's not considered an error, a handle to the existing torrent is returned.
- update_subscribe
- on by default and means that this torrent will be part of state updates when calling post_torrent_updates().
- super_seeding
- sets the torrent into super seeding/initial seeding mode. If the torrent is not a seed, this flag has no effect.
- sequential_download
- sets the sequential download state for the torrent. In this mode the piece picker will pick pieces with low index numbers before pieces with high indices. The actual pieces that are picked depend on other factors still, such as which pieces a peer has and whether it is in parole mode or "prefer whole pieces"-mode. Sequential mode is not ideal for streaming media. For that, see set_piece_deadline() instead.
- stop_when_ready
When this flag is set, the torrent will force stop whenever it transitions from a non-data-transferring state into a data-transferring state (referred to as being ready to download or seed). This is useful for torrents that should not start downloading or seeding yet, but want to be made ready to do so. A torrent may need to have its files checked for instance, so it needs to be started and possibly queued for checking (auto-managed and started) but as soon as it's done, it should be stopped.
Force stopped means auto-managed is set to false and it's paused. As if the auto_manages flag is cleared and the paused flag is set on the torrent.
Note that the torrent may transition into a downloading state while calling this function, and since the logic is edge triggered you may miss the edge. To avoid this race, if the torrent already is in a downloading state when this call is made, it will trigger the stop-when-ready immediately.
When the stop-when-ready logic fires, the flag is cleared. Any subsequent transitions between downloading and non-downloading states will not be affected, until this function is used to set it again.
The behavior is more robust when setting this flag as part of adding the torrent. See add_torrent_params.
The stop-when-ready flag fixes the inherent race condition of waiting for the state_changed_alert and then call pause(). The download/seeding will most likely start in between posting the alert and receiving the call to pause.
A downloading state is one where peers are being connected. Which means just downloading the metadata via the ut_metadata extension counts as a downloading state. In order to stop a torrent once the metadata has been downloaded, instead set all file priorities to dont_download
- override_trackers
- when this flag is set, the tracker list in the add_torrent_params object override any trackers from the torrent file. If the flag is not set, the trackers from the add_torrent_params object will be added to the list of trackers used by the torrent. This flag is set by read_resume_data() if there are trackers present in the resume data file. This effectively makes the trackers saved in the resume data take precedence over the original trackers. This includes if there's an empty list of trackers, to support the case where they were explicitly removed in the previous session.
- override_web_seeds
- If this flag is set, the web seeds from the add_torrent_params object will override any web seeds in the torrent file. If it's not set, web seeds in the add_torrent_params object will be added to the list of web seeds used by the torrent. This flag is set by read_resume_data() if there are web seeds present in the resume data file. This effectively makes the web seeds saved in the resume data take precedence over the original ones. This includes if there's an empty list of web seeds, to support the case where they were explicitly removed in the previous session.
- need_save_resume
- if this flag is set (which it is by default) the torrent will be considered needing to save its resume data immediately as it's added. New torrents that don't have any resume data should do that. This flag is cleared by a successful call to save_resume_data()
- disable_dht
- set this flag to disable DHT for this torrent. This lets you have the DHT enabled for the whole client, and still have specific torrents not participating in it. i.e. not announcing to the DHT nor picking up peers from it.
- disable_lsd
- set this flag to disable local service discovery for this torrent.
- disable_pex
- set this flag to disable peer exchange for this torrent.
- all
- all torrent flags combined. Can conveniently be used when creating masks for flags
pex_flags_t
Declared in "libtorrent/pex_flags.hpp"
- pex_encryption
- the peer supports protocol encryption
- pex_seed
- the peer is a seed
- pex_utp
- the peer supports the uTP, transport protocol over UDP.
- pex_holepunch
- the peer supports the holepunch extension If this flag is received from a peer, it can be used as a rendezvous point in case direct connections to the peer fail
download_priority_t
Declared in "libtorrent/download_priority.hpp"
- dont_download
- Don't download the file or piece. Partial pieces may still be downloaded when setting file priorities.
- default_priority
- The default priority for files and pieces.
- low_priority
- The lowest priority for files and pieces.
- top_priority
- The highest priority for files and pieces.
| Author: | Arvid Norberg<EMAIL_ADDRESS>|
|---|---|
| Version: | 1.2.6 |
DHT
[report issue]dht_settings
Declared in "libtorrent/kademlia/dht_settings.hpp"
structure used to hold configuration options for the DHT
The dht_settings struct used to contain a service_port member to control which port the DHT would listen on and send messages from. This field is deprecated and ignored. libtorrent always tries to open the UDP socket on the same port as the TCP socket.
struct dht_settings { int max_peers_reply = 100; int search_branching = 5; int max_fail_count = 20; int max_torrents = 2000; int max_dht_items = 700; int max_peers = 500; int max_torrent_search_reply = 20; bool restrict_routing_ips = true; bool restrict_search_ips = true; bool extended_routing_table = true; bool aggressive_lookups = true; bool privacy_lookups = false; bool enforce_node_id = false; bool ignore_dark_internet = true; int block_timeout = 5 * 60; int block_ratelimit = 5; bool read_only = false; int item_lifetime = 0; int upload_rate_limit = 8000; int sample_infohashes_interval = 21600; int max_infohashes_sample_count = 20; };[report issue]
- max_peers_reply
- the maximum number of peers to send in a reply to get_peers
- search_branching
- 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
- max_fail_count
- 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.
- max_torrents
- the total number of torrents to track from the DHT. This is simply an upper limit to make sure malicious DHT nodes cannot make us allocate an unbounded amount of memory.
- max_dht_items
- max number of items the DHT will store
- max_peers
- the max number of peers to store per torrent (for the DHT)
- max_torrent_search_reply
- the max number of torrents to return in a torrent search query to the DHT
- restrict_routing_ips
determines if the routing table entries should restrict entries to one per IP. This defaults to true, which helps mitigate some attacks on the DHT. It prevents adding multiple nodes with IPs with a very close CIDR distance.
when set, nodes whose IP address that's in the same /24 (or /64 for IPv6) range in the same routing table bucket. This is an attempt to mitigate node ID spoofing attacks also restrict any IP to only have a single entry in the whole routing table
- restrict_search_ips
- determines if DHT searches should prevent adding nodes with IPs with very close CIDR distance. This also defaults to true and helps mitigate certain attacks on the DHT.
- extended_routing_table
- makes the first buckets in the DHT routing table fit 128, 64, 32 and 16 nodes respectively, as opposed to the standard size of 8. All other buckets have size 8 still.
- aggressive_lookups
- slightly changes the lookup behavior in terms of how many outstanding requests we keep. Instead of having branch factor be a hard limit, we always keep branch factor outstanding requests to the closest nodes. i.e. every time we get results back with closer nodes, we query them right away. It lowers the lookup times at the cost of more outstanding queries.
- privacy_lookups
- when set, perform lookups in a way that is slightly more expensive, but which minimizes the amount of information leaked about you.
- enforce_node_id
- when set, node's whose IDs that are not correctly generated based on its external IP are ignored. When a query arrives from such node, an error message is returned with a message saying "invalid node ID".
- ignore_dark_internet
- ignore DHT messages from parts of the internet we wouldn't expect to see any traffic from
- block_timeout
- the number of seconds a DHT node is banned if it exceeds the rate limit. The rate limit is averaged over 10 seconds to allow for bursts above the limit.
- block_ratelimit
- the max number of packets per second a DHT node is allowed to send without getting banned.
- read_only
- when set, the other nodes won't keep this node in their routing tables, it's meant for low-power and/or ephemeral devices that cannot support the DHT, it is also useful for mobile devices which are sensitive to network traffic and battery life. this node no longer responds to 'query' messages, and will place a 'ro' key (value = 1) in the top-level message dictionary of outgoing query messages.
- item_lifetime
- the number of seconds a immutable/mutable item will be expired. default is 0, means never expires.
- upload_rate_limit
- the number of bytes per second (on average) the DHT is allowed to send. If the incoming requests causes to many bytes to be sent in responses, incoming requests will be dropped until the quota has been replenished.
- sample_infohashes_interval
- the info-hashes sample recomputation interval (in seconds). The node will precompute a subset of the tracked info-hashes and return that instead of calculating it upon each request. The permissible range is between 0 and 21600 seconds (inclusive).
- max_infohashes_sample_count
- the maximum number of elements in the sampled subset of info-hashes. If this number is too big, expect the DHT storage implementations to clamp it in order to allow UDP packets go through
dht_storage_counters
Declared in "libtorrent/kademlia/dht_storage.hpp"
This structure hold the relevant counters for the storage
struct dht_storage_counters { void reset (); std::int32_t torrents = 0; std::int32_t peers = 0; std::int32_t immutable_data = 0; std::int32_t mutable_data = 0; };[report issue]
dht_storage_interface
Declared in "libtorrent/kademlia/dht_storage.hpp"
The DHT storage interface is a pure virtual class that can be implemented to customize how the data for the DHT is stored.
The default storage implementation uses three maps in RAM to save the peers, mutable and immutable items and it's designed to provide a fast and fully compliant behavior of the BEPs.
libtorrent comes with one built-in storage implementation: dht_default_storage (private non-accessible class). Its constructor function is called dht_default_storage_constructor(). You should know that if this storage becomes full of DHT items, the current implementation could degrade in performance.
struct dht_storage_interface { virtual void update_node_ids (std::vector<node_id> const& ids) = 0; virtual bool get_peers (sha1_hash const& info_hash , bool noseed, bool scrape, address const& requester , entry& peers) const = 0; virtual void announce_peer (sha1_hash const& info_hash , tcp::endpoint const& endp , string_view name, bool seed) = 0; virtual bool get_immutable_item (sha1_hash const& target , entry& item) const = 0; virtual void put_immutable_item (sha1_hash const& target , span<char const> buf , address const& addr) = 0; virtual bool get_mutable_item_seq (sha1_hash const& target , sequence_number& seq) const = 0; virtual bool get_mutable_item (sha1_hash const& target , sequence_number seq, bool force_fill , entry& item) const = 0; virtual void put_mutable_item (sha1_hash const& target , span<char const> buf , signature const& sig , sequence_number seq , public_key const& pk , span<char const> salt , address const& addr) = 0; virtual int get_infohashes_sample (entry& item) = 0; virtual void tick () = 0; virtual dht_storage_counters counters () const = 0; };[report issue]
update_node_ids()
virtual void update_node_ids (std::vector<node_id> const& ids) = 0;
This member function notifies the list of all node's ids of each DHT running inside libtorrent. It's advisable that the concrete implementation keeps a copy of this list for an eventual prioritization when deleting an element to make room for a new one.
[report issue]get_peers()
virtual bool get_peers (sha1_hash const& info_hash , bool noseed, bool scrape, address const& requester , entry& peers) const = 0;
This function retrieve the peers tracked by the DHT corresponding to the given info_hash. You can specify if you want only seeds and/or you are scraping the data.
For future implementers: If the torrent tracked contains a name, such a name must be stored as a string in peers["n"]
If the scrape parameter is true, you should fill these keys:
- peers["BFpe"]
- with the standard bit representation of a 256 bloom filter containing the downloaders
- peers["BFsd"]
- with the standard bit representation of a 256 bloom filter containing the seeders
If the scrape parameter is false, you should fill the key peers["values"] with a list containing a subset of peers tracked by the given info_hash. Such a list should consider the value of dht_settings::max_peers_reply. If noseed is true only peers marked as no seed should be included.
returns true if the maximum number of peers are stored for this info_hash.
[report issue]announce_peer()
virtual void announce_peer (sha1_hash const& info_hash , tcp::endpoint const& endp , string_view name, bool seed) = 0;
This function is named announce_peer for consistency with the upper layers, but has nothing to do with networking. Its only responsibility is store the peer in such a way that it's returned in the entry with the lookup_peers.
The name parameter is the name of the torrent if provided in the announce_peer DHT message. The length of this value should have a maximum length in the final storage. The default implementation truncate the value for a maximum of 50 characters.
[report issue]get_immutable_item()
virtual bool get_immutable_item (sha1_hash const& target , entry& item) const = 0;
This function retrieves the immutable item given its target hash.
For future implementers: The value should be returned as an entry in the key item["v"].
returns true if the item is found and the data is returned inside the (entry) out parameter item.
[report issue]put_immutable_item()
virtual void put_immutable_item (sha1_hash const& target , span<char const> buf , address const& addr) = 0;
Store the item's data. This layer is only for storage. The authentication of the item is performed by the upper layer.
For implementers: This data can be stored only if the target is not already present. The implementation should consider the value of dht_settings::max_dht_items.
[report issue]get_mutable_item_seq()
virtual bool get_mutable_item_seq (sha1_hash const& target , sequence_number& seq) const = 0;
This function retrieves the sequence number of a mutable item.
returns true if the item is found and the data is returned inside the out parameter seq.
[report issue]get_mutable_item()
virtual bool get_mutable_item (sha1_hash const& target , sequence_number seq, bool force_fill , entry& item) const = 0;
This function retrieves the mutable stored in the DHT.
For implementers: The item sequence should be stored in the key item["seq"]. if force_fill is true or (0 <= seq and seq < item["seq"]) the following keys should be filled item["v"] - with the value no encoded. item["sig"] - with a string representation of the signature. item["k"] - with a string representation of the public key.
returns true if the item is found and the data is returned inside the (entry) out parameter item.
[report issue]put_mutable_item()
virtual void put_mutable_item (sha1_hash const& target , span<char const> buf , signature const& sig , sequence_number seq , public_key const& pk , span<char const> salt , address const& addr) = 0;
Store the item's data. This layer is only for storage. The authentication of the item is performed by the upper layer.
For implementers: The sequence number should be checked if the item is already present. The implementation should consider the value of dht_settings::max_dht_items.
[report issue]get_infohashes_sample()
virtual int get_infohashes_sample (entry& item) = 0;
This function retrieves a sample info-hashes
For implementers: The info-hashes should be stored in ["samples"] (N x 20 bytes). the following keys should be filled item["interval"] - the subset refresh interval in seconds. item["num"] - number of info-hashes in storage.
Internally, this function is allowed to lazily evaluate, cache and modify the actual sample to put in item
returns the number of info-hashes in the sample.
[report issue]tick()
virtual void tick () = 0;
This function is called periodically (non-constant frequency).
For implementers: Use this functions for expire peers or items or any other storage cleanup.
[report issue]counters()
virtual dht_storage_counters counters () const = 0;
return stats counters for the store
[report issue]dht_state
Declared in "libtorrent/kademlia/dht_state.hpp"
This structure helps to store and load the state of the dht_tracker. At this moment the library is only a dual stack implementation of the DHT. See BEP 32
struct dht_state { void clear (); node_ids_t nids; std::vector<udp::endpoint> nodes; std::vector<udp::endpoint> nodes6; };[report issue]
- nodes
- the bootstrap nodes saved from the buckets node
- nodes6
- the bootstrap nodes saved from the IPv6 buckets node
dht_default_storage_constructor()
Declared in "libtorrent/kademlia/dht_storage.hpp"
std::unique_ptr<dht_storage_interface> dht_default_storage_constructor ( dht_settings const& settings);
constructor for the default DHT storage. The DHT storage is responsible for maintaining peers and mutable and immutable items announced and stored/put to the DHT node.
[report issue]sign_mutable_item()
Declared in "libtorrent/kademlia/item.hpp"
signature sign_mutable_item ( span<char const> v , span<char const> salt , sequence_number seq , public_key const& pk , secret_key const& sk);
given a byte range v and an optional byte range salt, a sequence number, public key pk (must be 32 bytes) and a secret key sk (must be 64 bytes), this function produces a signature which is written into a 64 byte buffer pointed to by sig. The caller is responsible for allocating the destination buffer that's passed in as the sig argument. Typically it would be allocated on the stack.
[report issue]announce_flags_t
Declared in "libtorrent/kademlia/announce_flags.hpp"
- seed
- announce to DHT as a seed
- implied_port
- announce to DHT with the implied-port flag set. This tells the network to use your source UDP port as your listen port, rather than the one specified in the message. This may improve the chances of traversing NATs when using uTP.
- ssl_torrent
- Specify the port number for the SSL listen socket in the DHT announce.
| Author: | Arvid Norberg<EMAIL_ADDRESS>|
|---|---|
| Version: | 1.2.6 |
Session
[report issue]stats_metric
Declared in "libtorrent/session_stats.hpp"
describes one statistics metric from the session. For more information, see the session statistics section.
struct stats_metric { char const* name; int value_index; metric_type_t type; };[report issue]
- name
- the name of the counter or gauge
- value_index type
- the index into the session stats array, where the underlying value of this counter or gauge is found. The session stats array is part of the session_stats_alert object.
session_handle
Declared in "libtorrent/session_handle.hpp"
this class provides a non-owning handle to a session and a subset of the interface of the session class. If the underlying session is destructed any handle to it will no longer be valid. is_valid() will return false and any operation on it will throw a system_error exception, with error code invalid_session_handle.
struct session_handle { bool is_valid () const; void load_state (bdecode_node const& e, save_state_flags_t flags = save_state_flags_t::all()); void save_state (entry& e, save_state_flags_t flags = save_state_flags_t::all()) const; void refresh_torrent_status (std::vector<torrent_status>* ret , status_flags_t flags = {}) const; std::vector<torrent_status> get_torrent_status ( std::function<bool(torrent_status const&)> const& pred , status_flags_t flags = {}) const; void post_torrent_updates (status_flags_t flags = status_flags_t::all()); void post_session_stats (); void post_dht_stats (); torrent_handle find_torrent (sha1_hash const& info_hash) const; std::vector<torrent_handle> get_torrents () const; void async_add_torrent (add_torrent_params&& params); torrent_handle add_torrent (add_torrent_params const& params); torrent_handle add_torrent (add_torrent_params&& params); void async_add_torrent (add_torrent_params const& params); torrent_handle add_torrent (add_torrent_params const& params, error_code& ec); torrent_handle add_torrent (add_torrent_params&& params, error_code& ec); void resume (); void pause (); bool is_paused () const; void get_cache_info (cache_status* ret, torrent_handle h = torrent_handle(), int flags = 0) const; bool is_dht_running () const; void set_dht_settings (dht::dht_settings const& settings); dht::dht_settings get_dht_settings () const; void set_dht_storage (dht::dht_storage_constructor_type sc); void add_dht_node (std::pair<std::string, int> const& node); void dht_get_item (sha1_hash const& target); void dht_get_item (std::array<char, 32> key , std::string salt = std::string()); sha1_hash dht_put_item (entry data); void dht_put_item (std::array<char, 32> key , std::function<void(entry&, std::array<char, 64>& , std::int64_t&, std::string const&)> cb , std::string salt = std::string()); void dht_get_peers (sha1_hash const& info_hash); void dht_announce (sha1_hash const& info_hash, int port = 0, dht::announce_flags_t flags = {}); void dht_live_nodes (sha1_hash const& nid); void dht_sample_infohashes (udp::endpoint const& ep, sha1_hash const& target); void dht_direct_request (udp::endpoint const& ep, entry const& e, void* userdata = nullptr); void add_extension (std::function<std::shared_ptr<torrent_plugin>( torrent_handle const&, void*)> ext); void add_extension (std::shared_ptr<plugin> ext); ip_filter get_ip_filter () const; void set_ip_filter (ip_filter const& f); void set_port_filter (port_filter const& f); bool is_listening () const; unsigned short listen_port () const; unsigned short ssl_listen_port () const; ip_filter get_peer_class_filter () const; void set_peer_class_filter (ip_filter const& f); void set_peer_class_type_filter (peer_class_type_filter const& f); peer_class_type_filter get_peer_class_type_filter () const; peer_class_t create_peer_class (char const* name); void delete_peer_class (peer_class_t cid); peer_class_info get_peer_class (peer_class_t cid) const; void set_peer_class (peer_class_t cid, peer_class_info const& pci); void remove_torrent (const torrent_handle& h, remove_flags_t options = {}); void apply_settings (settings_pack&& s); settings_pack get_settings () const; void apply_settings (settings_pack const& s); void pop_alerts (std::vector<alert*>* alerts); void set_alert_notify (std::function<void()> const& fun); alert* wait_for_alert (time_duration max_wait); void delete_port_mapping (port_mapping_t handle); std::vector<port_mapping_t> add_port_mapping (portmap_protocol t, int external_port, int local_port); void reopen_network_sockets (reopen_network_flags_t options = reopen_map_ports); std::shared_ptr<aux::session_impl> native_handle () const; static constexpr save_state_flags_t save_settings = 0_bit; static constexpr save_state_flags_t save_dht_settings = 1_bit; static constexpr save_state_flags_t save_dht_state = 2_bit; static constexpr peer_class_t global_peer_class_id {0}; static constexpr peer_class_t tcp_peer_class_id {1}; static constexpr peer_class_t local_peer_class_id {2}; static constexpr remove_flags_t delete_files = 0_bit; static constexpr remove_flags_t delete_partfile = 1_bit; static constexpr session_flags_t add_default_plugins = 0_bit; static constexpr portmap_protocol udp = portmap_protocol::udp; static constexpr portmap_protocol tcp = portmap_protocol::tcp; static constexpr reopen_network_flags_t reopen_map_ports = 0_bit; };[report issue]
is_valid()
bool is_valid () const;
returns true if this handle refers to a valid session object. If the session has been destroyed, all session_handle objects will expire and not be valid.
[report issue]load_state() save_state()
void load_state (bdecode_node const& e, save_state_flags_t flags = save_state_flags_t::all()); void save_state (entry& e, save_state_flags_t flags = save_state_flags_t::all()) const;
loads and saves all session settings, including dht_settings, encryption settings and proxy settings. save_state writes all keys to the entry that's passed in, which needs to either not be initialized, or initialized as a dictionary.
load_state expects a bdecode_node which can be built from a bencoded buffer with bdecode().
The flags argument is used to filter which parts of the session state to save or load. By default, all state is saved/restored (except for the individual torrents).
When saving settings, there are two fields that are not loaded. peer_fingerprint and user_agent. Those are left as configured by the session_settings passed to the session constructor or subsequently set via apply_settings().
[report issue]get_torrent_status() refresh_torrent_status()
void refresh_torrent_status (std::vector<torrent_status>* ret , status_flags_t flags = {}) const; std::vector<torrent_status> get_torrent_status ( std::function<bool(torrent_status const&)> const& pred , status_flags_t flags = {}) const;
Note
these calls are potentially expensive and won't scale well with lots of torrents. If you're concerned about performance, consider using post_torrent_updates() instead.
get_torrent_status returns a vector of the torrent_status for every torrent which satisfies pred, which is a predicate function which determines if a torrent should be included in the returned set or not. Returning true means it should be included and false means excluded. The flags argument is the same as to torrent_handle::status(). Since pred is guaranteed to be called for every torrent, it may be used to count the number of torrents of different categories as well.
refresh_torrent_status takes a vector of torrent_status structs (for instance the same vector that was returned by get_torrent_status() ) and refreshes the status based on the handle member. It is possible to use this function by first setting up a vector of default constructed torrent_status objects, only initializing the handle member, in order to request the torrent status for multiple torrents in a single call. This can save a significant amount of time if you have a lot of torrents.
Any torrent_status object whose handle member is not referring to a valid torrent are ignored.
The intended use of these functions is to start off by calling get_torrent_status() to get a list of all torrents that match your criteria. Then call refresh_torrent_status() on that list. This will only refresh the status for the torrents in your list, and thus ignore all other torrents you might be running. This may save a significant amount of time, especially if the number of torrents you're interested in is small. In order to keep your list of interested torrents up to date, you can either call get_torrent_status() from time to time, to include torrents you might have become interested in since the last time. In order to stop refreshing a certain torrent, simply remove it from the list.
[report issue]post_torrent_updates()
void post_torrent_updates (status_flags_t flags = status_flags_t::all());
This functions instructs the session to post the state_update_alert, containing the status of all torrents whose state changed since the last time this function was called.
Only torrents who has the state subscription flag set will be included. This flag is on by default. See add_torrent_params. the flags argument is the same as for torrent_handle::status(). see status_flags_t in torrent_handle.
[report issue]post_session_stats()
void post_session_stats ();
This function will post a session_stats_alert object, containing a snapshot of the performance counters from the internals of libtorrent. To interpret these counters, query the session via session_stats_metrics().
For more information, see the session statistics section.
[report issue]post_dht_stats()
void post_dht_stats ();
This will cause a dht_stats_alert to be posted.
[report issue]find_torrent() get_torrents()
torrent_handle find_torrent (sha1_hash const& info_hash) const; std::vector<torrent_handle> get_torrents () const;
find_torrent() looks for a torrent with the given info-hash. In case there is such a torrent in the session, a torrent_handle to that torrent is returned. In case the torrent cannot be found, an invalid torrent_handle is returned.
See torrent_handle::is_valid() to know if the torrent was found or not.
get_torrents() returns a vector of torrent_handles to all the torrents currently in the session.
[report issue]add_torrent() async_add_torrent()
void async_add_torrent (add_torrent_params&& params); torrent_handle add_torrent (add_torrent_params const& params); torrent_handle add_torrent (add_torrent_params&& params); void async_add_torrent (add_torrent_params const& params); torrent_handle add_torrent (add_torrent_params const& params, error_code& ec); torrent_handle add_torrent (add_torrent_params&& params, error_code& ec);
You add torrents through the add_torrent() function where you give an object with all the parameters. The add_torrent() overloads will block until the torrent has been added (or failed to be added) and returns an error code and a torrent_handle. In order to add torrents more efficiently, consider using async_add_torrent() which returns immediately, without waiting for the torrent to add. Notification of the torrent being added is sent as add_torrent_alert.
The overload that does not take an error_code throws an exception on error and is not available when building without exception support. The torrent_handle returned by add_torrent() can be used to retrieve information about the torrent's progress, its peers etc. It is also used to abort a torrent.
If the torrent you are trying to add already exists in the session (is either queued for checking, being checked or downloading) add_torrent() will throw system_error which derives from std::exception unless duplicate_is_error is set to false. In that case, add_torrent() will return the handle to the existing torrent.
all torrent_handles must be destructed before the session is destructed!
[report issue]pause() resume() is_paused()
void resume (); void pause (); bool is_paused () const;
Pausing the session has the same effect as pausing every torrent in it, except that torrents will not be resumed by the auto-manage mechanism. Resuming will restore the torrents to their previous paused state. i.e. the session pause state is separate from the torrent pause state. A torrent is inactive if it is paused or if the session is paused.
[report issue]get_cache_info()
void get_cache_info (cache_status* ret, torrent_handle h = torrent_handle(), int flags = 0) const;
Fills in the cache_status struct with information about the given torrent. If flags is session::disk_cache_no_pieces the cache_status::pieces field will not be set. This may significantly reduce the cost of this call.
[report issue]get_dht_settings() is_dht_running() set_dht_settings()
bool is_dht_running () const; void set_dht_settings (dht::dht_settings const& settings); dht::dht_settings get_dht_settings () const;
set_dht_settings sets some parameters available to the dht node. See dht_settings for more information.
is_dht_running() returns true if the DHT support has been started and false otherwise.
get_dht_settings() returns the current settings
[report issue]set_dht_storage()
void set_dht_storage (dht::dht_storage_constructor_type sc);
set_dht_storage set a dht custom storage constructor function to be used internally when the dht is created.
Since the dht storage is a critical component for the dht behavior, this function will only be effective the next time the dht is started. If you never touch this feature, a default map-memory based storage is used.