forked from premiere/premiere-libtorrent
302 lines
8.5 KiB
ReStructuredText
302 lines
8.5 KiB
ReStructuredText
=================
|
|
creating torrents
|
|
=================
|
|
|
|
:Author: Arvid Norberg, arvid@rasterbar.com
|
|
|
|
.. contents:: Table of contents
|
|
:depth: 2
|
|
:backlinks: none
|
|
|
|
overview
|
|
========
|
|
|
|
This section describes the functions and classes that are used
|
|
to create torrent files. It is a layered API with low level classes
|
|
and higher level convenience functions. A torrent is created in 4
|
|
steps:
|
|
|
|
1. first the files that will be part of the torrent are determined.
|
|
2. the torrent properties are set, such as tracker url, web seeds,
|
|
DHT nodes etc.
|
|
3. Read through all the files in the torrent, SHA-1 all the data
|
|
and set the piece hashes.
|
|
4. The torrent is bencoded into a file or buffer.
|
|
|
|
If there are a lot of files and or deep directoy hierarchies to
|
|
traverse, step one can be time consuming.
|
|
|
|
Typically step 3 is by far the most time consuming step, since it
|
|
requires to read all the bytes from all the files in the torrent.
|
|
|
|
All of these classes and functions are declared by including
|
|
``libtorrent/create_torrent.hpp``.
|
|
|
|
high level example
|
|
==================
|
|
|
|
::
|
|
|
|
file_storage fs;
|
|
|
|
// recursively adds files in directories
|
|
add_files(fs, "./my_torrent");
|
|
|
|
create_torrent t(fs);
|
|
t.add_tracker("http://my.tracker.com/announce");
|
|
t.set_creator("libtorrent example");
|
|
|
|
// reads the files and calculates the hashes
|
|
set_piece_hashes(t, ".");
|
|
|
|
ofstream out("my_torrent.torrent", std::ios_base::binary);
|
|
bencode(std::ostream_iterator<char>(out), t.generate());
|
|
|
|
add_files
|
|
=========
|
|
|
|
::
|
|
|
|
template <class Pred>
|
|
void add_files(file_storage& fs, boost::filesystem::path const& path, Pred p);
|
|
template <class Pred>
|
|
void add_files(file_storage& fs, boost::filesystem::wpath const& path, Pred p);
|
|
|
|
void add_files(file_storage& fs, boost::filesystem::path const& path);
|
|
void add_files(file_storage& fs, boost::filesystem::wpath const& path);
|
|
|
|
Adds the file specified by ``path`` to the ``file_storage`` object. In case ``path``
|
|
refers to a diretory, files will be added recursively from the directory.
|
|
|
|
If specified, the predicate ``p`` is called once for every file and directory that
|
|
is encountered. files for which ``p`` returns true are added, and directories for
|
|
which ``p`` returns true are traversed. ``p`` must have the following signature::
|
|
|
|
bool Pred(boost::filesystem::path const& p);
|
|
|
|
and for the wpath version::
|
|
|
|
bool Pred(boost::filesystem::wpath const& p);
|
|
|
|
The path that is passed in to the predicate is the full path of the file or
|
|
directory. If no predicate is specified, all files are added, and all directories
|
|
are traveresed.
|
|
|
|
The ".." directory is never traversed.
|
|
|
|
set_piece_hashes()
|
|
==================
|
|
|
|
::
|
|
|
|
template <class Fun>
|
|
void set_piece_hashes(create_torrent& t, boost::filesystem::path const& p, Fun f);
|
|
template <class Fun>
|
|
void set_piece_hashes(create_torrent& t, boost::filesystem::wpath const& p, Fun f);
|
|
|
|
void set_piece_hashes(create_torrent& t, boost::filesystem::path const& p);
|
|
void set_piece_hashes(create_torrent& t, boost::filesystem::wpath const& p);
|
|
|
|
This function will assume that the files added to the torrent file exists at path
|
|
``p``, read those files and hash the content and set the hashes in the ``create_torrent``
|
|
object. The optional function ``f`` is called in between every hash that is set. ``f``
|
|
must have the following signature::
|
|
|
|
void Fun(int);
|
|
|
|
file_storage
|
|
============
|
|
|
|
The ``file_storage`` class represents a file list and the piece
|
|
size. Everything necessary to interpret a regular bittorrent storage
|
|
file structure. Its synopsis::
|
|
|
|
class file_storage
|
|
{
|
|
public:
|
|
|
|
bool is_valid() const;
|
|
|
|
void add_file(file_entry const& e);
|
|
void add_file(fs::path const& p, size_type size);
|
|
void add_file(fs::wpath const& p, size_type size);
|
|
void rename_file(int index, std::string const& new_filename);
|
|
void rename_file(int index, std::wstring const& new_filename);
|
|
|
|
std::vector<file_slice> map_block(int piece, size_type offset
|
|
, int size) const;
|
|
peer_request map_file(int file, size_type offset, int size) const;
|
|
|
|
typedef std::vector<file_entry>::const_iterator iterator;
|
|
typedef std::vector<file_entry>::const_reverse_iterator reverse_iterator;
|
|
|
|
iterator begin() const;
|
|
iterator end() const;
|
|
reverse_iterator rbegin();
|
|
reverse_iterator rend() const;
|
|
int num_files() const;
|
|
|
|
file_entry const& at(int index) const;
|
|
|
|
size_type total_size() const;
|
|
void set_num_pieces(int n);
|
|
int num_pieces() const;
|
|
void set_piece_length(int l);
|
|
int piece_length() const;
|
|
int piece_size(int index) const;
|
|
|
|
void set_name(std::string const& n);
|
|
void set_name(std::wstring const& n);
|
|
const std::string& name() const;
|
|
|
|
void swap(file_storage& ti);
|
|
}
|
|
|
|
|
|
create_torrent
|
|
==============
|
|
|
|
The ``create_torrent`` class has the following synopsis::
|
|
|
|
|
|
struct create_torrent
|
|
{
|
|
create_torrent(file_storage& fs, int piece_size);
|
|
create_torrent(file_storage& fs);
|
|
create_torrent(torrent_info const& ti);
|
|
|
|
entry generate() const;
|
|
|
|
file_storage const& files() const;
|
|
|
|
void set_comment(char const* str);
|
|
void set_creator(char const* str);
|
|
void set_hash(int index, sha1_hash const& h);
|
|
void add_url_seed(std::string const& url);
|
|
void add_node(std::pair<std::string, int> const& node);
|
|
void add_tracker(std::string const& url, int tier = 0);
|
|
void set_priv(bool p);
|
|
|
|
int num_pieces() const;
|
|
int piece_length() const;
|
|
int piece_size(int i) const;
|
|
bool priv() const;
|
|
};
|
|
|
|
create_torrent()
|
|
----------------
|
|
|
|
::
|
|
|
|
create_torrent(file_storage& fs, int piece_size);
|
|
create_torrent(file_storage& fs);
|
|
create_torrent(torrent_info const& ti);
|
|
|
|
The ``piece_size`` is the size of each piece in bytes. It must
|
|
be a multiple of 16 kiB.
|
|
|
|
The constructor that does not take a piece_size will calculate
|
|
a piece size such that the torrent file is roughly 40 kB.
|
|
|
|
The overlad that takes a ``torrent_info`` object will make a verbatim
|
|
copy of its info dictionary (to preserve the info-hash). The copy of
|
|
the info dictionary will be used by ``generate()``. This means
|
|
that none of the member functions of create_torrent that affects
|
|
the content of the info dictionary (such as ``set_hash()``), will
|
|
have any affect.
|
|
|
|
generate()
|
|
----------
|
|
|
|
::
|
|
|
|
entry generate() const;
|
|
|
|
This function will generate the .torrent file as a bencode tree. In order to
|
|
generate the flat file, use the bencode() function.
|
|
|
|
It may be useful to add custom entries to the torrent file before bencoding it
|
|
and saving it to disk.
|
|
|
|
set_comment()
|
|
-------------
|
|
|
|
::
|
|
|
|
void set_comment(char const* str);
|
|
|
|
Sets the comment for the torrent. The string ``str`` should be utf-8 encoded.
|
|
The comment in a torrent file is optional.
|
|
|
|
set_creator()
|
|
-------------
|
|
|
|
::
|
|
|
|
void set_creator(char const* str);
|
|
|
|
Sets the creator of the torrent. The string ``str`` should be utf-8 encoded.
|
|
This is optional.
|
|
|
|
set_hash()
|
|
----------
|
|
|
|
::
|
|
|
|
void set_hash(int index, sha1_hash const& h);
|
|
|
|
This sets the SHA-1 hash for the specified piece (``index``). You are required
|
|
to set the hash for every piece in the torrent before generating it. If you have
|
|
the files on disk, you can use the high level convenience function to do this.
|
|
See `set_piece_hashes()`_.
|
|
|
|
add_url_seed()
|
|
--------------
|
|
|
|
::
|
|
|
|
void add_url_seed(std::string const& url);
|
|
|
|
This adds a url seed to the torrent. You can have any number of url seeds. For a
|
|
single file torrent, this should be an HTTP url, pointing to a file with identical
|
|
content as the file of the torrent. For a multi-file torrent, it should point to
|
|
a directory containing a directory with the same name as this torrent, and all the
|
|
files of the torrent in it.
|
|
|
|
add_node()
|
|
----------
|
|
|
|
::
|
|
|
|
void add_node(std::pair<std::string, int> const& node);
|
|
|
|
This adds a DHT node to the torrent. This especially useful if you're creating a
|
|
tracker less torrent. It can be used by clients to bootstrap their DHT node from.
|
|
The node is a hostname and a port number where there is a DHT node running.
|
|
You can have any number of DHT nodes in a torrent.
|
|
|
|
add_tracker()
|
|
-------------
|
|
|
|
::
|
|
|
|
void add_tracker(std::string const& url, int tier = 0);
|
|
|
|
Adds a tracker to the torrent. This is not strictly required, but most torrents
|
|
use a tracker as their main source of peers. The url should be an http:// or udp://
|
|
url to a machine running a bittorrent tracker that accepts announces for this torrent's
|
|
info-hash. The tier is the fallback priority of the tracker. All trackers with tier 0 are
|
|
tried first (in any order). If all fail, trackers with tier 1 are tried. If all of those
|
|
fail, trackers with tier 2 are tried, and so on.
|
|
|
|
set_priv() priv()
|
|
-----------------
|
|
|
|
::
|
|
|
|
void set_priv(bool p);
|
|
bool priv() const;
|
|
|
|
Sets and queries the private flag of the torrent.
|
|
|