#158 save .torrent file obtained from DHT via magnet-link

[Anonymous]

it would be nice, in addition to the payload, to have an option to save the .torrent from subj. It would not have any trackers, but the file names, and hash-sums of the chunks, and infohash (I use "aria2c -V .torrent" to check the integrity of the files copied from one machine to another).

On the other hand, how would one share via DHT a previously downloaded payload of a torrent without explicitly specifying (a tracker-less) .torrent-file? Making a new .torrent,even with the same filenames, is likely to produce a different infohash, e.g. because of a different chunk-size. Sure, I can start aria2 with the same magnet-link, and download the .torrent again from the network. But it means aria2 depends on the presence of other active seeders who do our job (keeping the .torrent metadata).

[tujikawa]

Saving .torrent containing downloaded metadata is good option to keep current torrent file and use quick hash check. You can use -V with Magnet URI, but it costs overhead to retrieve metadata from swarm.

I think torrent file without seeders is useless(you cannot download file without them), so it is not bad to depend on active seeders. If you want to become a seeder for died swarm, then above mentioned option will help.

[tujikawa]

I added --bt-save-metadata option.

--bt-save-metadata[=true|false] Save metadata as .torrent file. This option has
effect only when BitTorrent Magnet URI is used.
The filename is name in metadata with suffix
.torrent. The directory to be saved is the same
directory where download file is saved. If the
same file already exists, metdata is not saved.

                          Possible Values: true,false
                          Default: false
                          Tags: #bittorrent