twisterp2pnetworkbittorrentblockchainipv6microbloggingsocial-networkdhtdecentralizedtwister-servertwister-ipv6twister-coretwisterarmyp2p-network
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
552 lines
17 KiB
552 lines
17 KiB
================= |
|
creating torrents |
|
================= |
|
|
|
:Author: Arvid Norberg, arvid@rasterbar.com |
|
:Version: 1.0.0 |
|
|
|
.. 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, std::string const& path, Pred p |
|
, boost::uint32_t flags = 0); |
|
template <class Pred> |
|
void add_files(file_storage& fs, std::wstring const& path, Pred p |
|
, boost::uint32_t flags = 0); |
|
|
|
void add_files(file_storage& fs, std::string const& path |
|
, boost::uint32_t flags = 0); |
|
void add_files(file_storage& fs, std::wstring const& path |
|
, boost::uint32_t flags = 0); |
|
|
|
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(std::string const& p); |
|
|
|
and for the wide string version:: |
|
|
|
bool Pred(std::wstring 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. |
|
|
|
The ``flags`` argument should be the same as the flags passed to the `create_torrent`_ |
|
constructor. |
|
|
|
set_piece_hashes() |
|
================== |
|
|
|
:: |
|
|
|
template <class Fun> |
|
void set_piece_hashes(create_torrent& t, std::string const& p, Fun f); |
|
template <class Fun> |
|
void set_piece_hashes(create_torrent& t, std::wstring const& p, Fun f); |
|
template <class Fun> |
|
void set_piece_hashes(create_torrent& t, std::string const& p, Fun f |
|
, error_code& ec); |
|
template <class Fun> |
|
void set_piece_hashes(create_torrent& t, std::wstring const& p, Fun f |
|
, error_code& ec); |
|
|
|
void set_piece_hashes(create_torrent& t, std::string const& p); |
|
void set_piece_hashes(create_torrent& t, std::wstring const& p); |
|
void set_piece_hashes(create_torrent& t, std::string const& p |
|
, error_code& ec); |
|
void set_piece_hashes(create_torrent& t, std::wstring const& p |
|
, error_code& ec); |
|
|
|
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); |
|
|
|
The overloads that don't take an ``error_code&`` may throw an exception in case of a |
|
file error, the other overloads sets the error code to reflect the error, if any. |
|
|
|
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; |
|
|
|
enum flags_t |
|
{ |
|
pad_file = 1, |
|
attribute_hidden = 2, |
|
attribute_executable = 4 |
|
}; |
|
|
|
void add_file(file_entry const& e); |
|
void add_file(std::string const& p, size_type size, int flags = 0); |
|
void add_file(std::wstring const& p, size_type size, int flags = 0); |
|
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<internal_file_entry>::const_iterator iterator; |
|
typedef std::vector<internal_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 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; |
|
|
|
// index accessors |
|
sha1_hash const& hash(int index) const; |
|
std::string const& symlink(int index) const; |
|
time_t mtime(int index) const; |
|
size_type file_base(int index) const; |
|
void set_file_base(int index, size_type off); |
|
std::string file_path(int index) const; |
|
std::string file_name(int index) const; |
|
size_type file_size(int index) const; |
|
bool pad_file_at(int index) const; |
|
size_type file_offset(int index) const; |
|
|
|
// iterator accessors |
|
sha1_hash hash(internal_file_entry const& fe) const; |
|
std::string const& symlink(internal_file_entry const& fe) const; |
|
time_t mtime(internal_file_entry const& fe) const; |
|
int file_index(internal_file_entry const& fe) const; |
|
size_type file_base(internal_file_entry const& fe) const; |
|
void set_file_base(internal_file_entry const& fe, size_type off); |
|
std::string file_path(internal_file_entry const& fe) const; |
|
std::string file_name(internal_file_entry const& fe) const; |
|
size_type file_size(internal_file_entry const& fe) const; |
|
bool pad_file_at(internal_file_entry const& fe) const; |
|
size_type file_offset(internal_file_entry const& fe) 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); |
|
} |
|
|
|
add_file() |
|
---------- |
|
|
|
:: |
|
|
|
void add_file(file_entry const& e); |
|
void add_file(std::string const& p, size_type size, int flags = 0); |
|
void add_file(std::wstring const& p, size_type size, int flags = 0); |
|
|
|
Adds a file to the file storage. The ``flags`` argument sets attributes on the file. |
|
The file attributes is an extension and may not work in all bittorrent clients. |
|
The possible arreibutes are:: |
|
|
|
pad_file |
|
attribute_hidden |
|
attribute_executable |
|
|
|
If more files than one are added, certain restrictions to their paths apply. |
|
In a multi-file file storage (torrent), all files must share the same root directory. |
|
|
|
That is, the first path element of all files must be the same. |
|
This shared path element is also set to the name of the torrent. It |
|
can be changed by calling ``set_name``. |
|
|
|
The built in functions to traverse a directory to add files will |
|
make sure this requirement is fulfilled. |
|
|
|
hash() symlink() mtime() file_path() file_size() pad_file_at() |
|
-------------------------------------------------------------- |
|
|
|
:: |
|
|
|
sha1_hash hash(int index) const; |
|
std::string const& symlink(int index) const; |
|
time_t mtime(int index) const; |
|
std::string file_path(int index) const; |
|
size_type file_size(int index) const; |
|
bool pad_file_at(int index) const; |
|
|
|
These functions are used to query attributes of files at |
|
a given index. |
|
|
|
The ``file_hash()`` is a sha-1 hash of the file, or 0 if none was |
|
provided in the torrent file. This can potentially be used to |
|
join a bittorrent network with other file sharing networks. |
|
|
|
The ``mtime()`` is the modification time is the posix |
|
time when a file was last modified when the torrent |
|
was created, or 0 if it was not included in the torrent file. |
|
|
|
``file_path()`` returns the full path to a file. |
|
|
|
``file_size()`` returns the size of a file. |
|
|
|
``pad_file_at()`` returns true if the file at the given |
|
index is a pad-file. |
|
|
|
file_base() set_file_base() |
|
--------------------------- |
|
|
|
:: |
|
|
|
size_type file_base(int index) const; |
|
void set_file_base(int index, size_type off); |
|
|
|
The file base of a file is the offset within the file on the filsystem |
|
where it starts to write. For the most part, this is always 0. It's |
|
possible to map several files (in the torrent) into a single file on |
|
the filesystem by making them all point to the same filename, but with |
|
different file bases, so that they don't overlap. |
|
``torrent_info::remap_files`` can be used to use a new file layout. |
|
|
|
create_torrent |
|
============== |
|
|
|
The ``create_torrent`` class has the following synopsis:: |
|
|
|
|
|
struct create_torrent |
|
{ |
|
enum { |
|
optimize = 1 |
|
, merkle = 2 |
|
, modification_time = 4 |
|
, symlinks = 8 |
|
, calculate_file_hashes = 16 |
|
}; |
|
create_torrent(file_storage& fs, int piece_size = 0, int pad_size_limit = -1 |
|
, int flags = optimize, int alignment = 0x4000); |
|
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 set_file_hash(int index, sha1_hash const& h); |
|
void add_url_seed(std::string const& url); |
|
void add_http_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_root_cert(std::string const& pem); |
|
void set_priv(bool p); |
|
|
|
int num_pieces() const; |
|
int piece_length() const; |
|
int piece_size(int i) const; |
|
bool priv() const; |
|
}; |
|
|
|
create_torrent() |
|
---------------- |
|
|
|
:: |
|
|
|
enum { |
|
optimize = 1 |
|
, merkle = 2 |
|
, modification_time = 4 |
|
, symlinks = 8 |
|
, calculate_file_hashes = 16 |
|
}; |
|
create_torrent(file_storage& fs, int piece_size = 0, int pad_size_limit = -1 |
|
, int flags = optimize, int alignment = 0x4000); |
|
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. If a piece size of 0 is specified, a |
|
piece_size will be calculated such that the torrent file is roughly 40 kB. |
|
|
|
If a ``pad_size_limit`` is specified (other than -1), any file larger than |
|
the specified number of bytes will be preceeded by a pad file to align it |
|
with the start of a piece. The pad_file_limit is ignored unless the |
|
``optimize`` flag is passed. Typically it doesn't make sense to set this |
|
any lower than 4kiB. |
|
|
|
The overload 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. |
|
|
|
The ``flags`` arguments specifies options for the torrent creation. It can |
|
be any combination of the following flags: |
|
|
|
optimize |
|
This will insert pad files to align the files to piece boundaries, for |
|
optimized disk-I/O. |
|
|
|
merkle |
|
This will create a merkle hash tree torrent. A merkle torrent cannot |
|
be opened in clients that don't specifically support merkle torrents. |
|
The benefit is that the resulting torrent file will be much smaller and |
|
not grow with more pieces. When this option is specified, it is |
|
recommended to have a fairly small piece size, say 64 kiB. |
|
When creating merkle torrents, the full hash tree is also generated |
|
and should be saved off separately. It is accessed through the |
|
``merkle_tree()`` function. |
|
|
|
modification_time |
|
This will include the file modification time as part of the torrent. |
|
This is not enabled by default, as it might cause problems when you |
|
create a torrent from separate files with the same content, hoping to |
|
yield the same info-hash. If the files have different modification times, |
|
with this option enabled, you would get different info-hashes for the |
|
files. |
|
|
|
symlink |
|
If this flag is set, files that are symlinks get a symlink attribute |
|
set on them and their data will not be included in the torrent. This |
|
is useful if you need to reconstruct a file hierarchy which contains |
|
symlinks. |
|
|
|
calculate_file_hashes |
|
If this is set, the `set_piece_hashes()`_ function will, as it calculates |
|
the piece hashes, also calculate the file hashes and add those associated |
|
with each file. Note that unless you use the `set_piece_hashes()`_ function, |
|
this flag will have no effect. |
|
|
|
``alignment`` is used when pad files are enabled. This is the size eligible |
|
files are aligned to. The default is the default bittorrent block size of |
|
16 kiB. It is common to align to the piece size of the torrent. |
|
|
|
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. |
|
|
|
If anything goes wrong during torrent generation, this function will return |
|
an empty ``entry`` structure. You can test for this condition by querying the |
|
type of the entry:: |
|
|
|
file_storage fs; |
|
// add file ... |
|
create_torrent t(fs); |
|
// add trackers and piece hashes ... |
|
e = t.generate(); |
|
|
|
if (e.type() == entry::undefined_t) |
|
{ |
|
// something went wrong |
|
} |
|
|
|
For instance, you cannot generate a torrent with 0 files in it. If you don't add |
|
any files to the ``file_storage``, torrent generation will fail. |
|
|
|
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()`_. |
|
|
|
set_file_hash() |
|
--------------- |
|
|
|
:: |
|
|
|
void set_file_hash(int index, sha1_hash const& h); |
|
|
|
This sets the sha1 hash for this file. This hash will end up under the key ``sha1`` |
|
associated with this file (for multi-file torrents) or in the root info dictionary |
|
for single-file torrents. |
|
|
|
add_url_seed() add_http_seed() |
|
------------------------------ |
|
|
|
:: |
|
|
|
void add_url_seed(std::string const& url); |
|
void add_http_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. |
|
|
|
The second function, ``add_http_seed()`` adds an HTTP seed instead. |
|
|
|
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_root_cert() |
|
--------------- |
|
|
|
:: |
|
|
|
void set_root_cert(std::string const& pem); |
|
|
|
This function sets an X.509 certificate in PEM format to the torrent. This makes the |
|
torrent an *SSL torrent*. An SSL torrent requires that each peer has a valid certificate |
|
signed by this root certificate. For SSL torrents, all peers are connecting over SSL |
|
connections. For more information on SSL torrents, see the manual_. |
|
|
|
The string is not the path to the cert, it's the actual content of the certificate, |
|
loaded into a std::string. |
|
|
|
.. _manual: manual.html#ssl-torrents |
|
|
|
set_priv() priv() |
|
----------------- |
|
|
|
:: |
|
|
|
void set_priv(bool p); |
|
bool priv() const; |
|
|
|
Sets and queries the private flag of the torrent. |
|
|
|
merkle_tree() |
|
------------- |
|
|
|
:: |
|
|
|
std::vector<sha1_hash> const& merkle_tree() const; |
|
|
|
This function returns the merkle hash tree, if the torrent was created as a merkle |
|
torrent. The tree is created by ``generate()`` and won't be valid until that function |
|
has been called. When creating a merkle tree torrent, the actual tree itself has to |
|
be saved off separately and fed into libtorrent the first time you start seeding it, |
|
through the ``torrent_info::set_merkle_tree()`` function. From that point onwards, the |
|
tree will be saved in the resume data. |
|
|
|
|
|
|
|
|