I have read through the manual and I cannot find the answer. Given a magnet link I would like to generate a torrent file so that it can be loaded on the next startup to avoid redownloading the metadata. I have tried the fast resume feature, but I still have to fetch meta data when I do it and that can take quite a bit of time. Examples that I have seen are for creating torrent files for a new torrent, where as I would like to create one matching a magnet uri.
Solution found here:
http://code.google.com/p/libtorrent/issues/detail?id=165#c5
See creating torrent:
http://www.rasterbar.com/products/libtorrent/make_torrent.html
Modify first lines:
file_storage fs;
// recursively adds files in directories
add_files(fs, "./my_torrent");
create_torrent t(fs);
To this:
torrent_info ti = handle.get_torrent_info()
create_torrent t(ti)
"handle" is from here:
torrent_handle add_magnet_uri(session& ses, std::string const& uri add_torrent_params p);
Also before creating torrent you have to make sure that metadata has been downloaded, do this by calling handle.has_metadata()
.
UPDATE
Seems like libtorrent python api is missing some of important c++ api that is required to create torrent from magnets, the example above won't work in python cause create_torrent
python class does not accept torrent_info as parameter (c++ has it available).
So I tried it another way, but also encountered a brick wall that makes it impossible, here is the code:
if handle.has_metadata():
torinfo = handle.get_torrent_info()
fs = libtorrent.file_storage()
for file in torinfo.files():
fs.add_file(file)
torfile = libtorrent.create_torrent(fs)
torfile.set_comment(torinfo.comment())
torfile.set_creator(torinfo.creator())
for i in xrange(0, torinfo.num_pieces()):
hash = torinfo.hash_for_piece(i)
torfile.set_hash(i, hash)
for url_seed in torinfo.url_seeds():
torfile.add_url_seed(url_seed)
for http_seed in torinfo.http_seeds():
torfile.add_http_seed(http_seed)
for node in torinfo.nodes():
torfile.add_node(node)
for tracker in torinfo.trackers():
torfile.add_tracker(tracker)
torfile.set_priv(torinfo.priv())
f = open(magnet_torrent, "wb")
f.write(libtorrent.bencode(torfile.generate()))
f.close()
There is an error thrown on this line:
torfile.set_hash(i, hash)
It expects hash to be const char*
but torrent_info.hash_for_piece(int)
returns class big_number
which has no api to convert it back to const char*.
When I find some time I will report this missing api bug to libtorrent developers, as currently it is impossible to create a .torrent file from a magnet uri when using python bindings.
torrent_info.orig_files()
is also missing in python bindings, I'm not sure whether torrent_info.files()
is sufficient.
UPDATE 2
I've created an issue on this, see it here: http://code.google.com/p/libtorrent/issues/detail?id=294
Star it so they fix it fast.
UPDATE 3
It is fixed now, there is a 0.16.0 release. Binaries for windows are also available.