Libtorrent Adds Support for BitTorrent v2

[ill88eagle]

Libtorrent has just released version 2.0, which is a potential game-changer. The BitTorrent library, which is used by popular clients including uTorrent Web, Deluge, and qBittorrent, adds support for the new BitTorrent v2 protocol specification. This opens the door to various new features and introduces a new torrent format, which creates a separate swarm.

So yea, while a lot of good ideas are finally being implemented it looks like swarm splitting is now a feature of libtorrent...

[Moe]

Don't know how deep you read into that, but they'll have hybrid torrents, so swarms won't be split unless the torrent is created exclusively v2.

I expect there to be much confusion.

But long term, the swarm merging and file hashing will be nice. Though, you can already get that with BiglyBT/Vuze. It is pretty neat in action.

[ill88eagle]

My primary concern is what will happen to the "ancient" torrents when v1 becomes deprecated. A lot of great *old* content is still available. I imagine clients will keep backwards compatibility, but long term, as you say, v1 torrents looks likely to be abandoned.

Also, how will an indexer like TPB deal with this? I imagine it will take a revamp of the guts to allow v2 torrent files to be uploaded, and then the UI to tell the user which type of torrent he is trying to download

[Moe]

I see no reason clients will drop v1 compatibility, so there should be no effect on older torrents. I don't see them being abandoned unless a lot of people upgrade clients and stop seeding what they were already seeding. But that would be no different than switching v1 clients now and not taking their old seeds for the ride.


Winston is an enigma. He is failing hard on making the smallest changes that could vastly improve user experience, but he is also quick to jump on new flashy technology.

There definitely needs to be upgrades to the upload system to accommodate parsing v2 torrent files and storing the new hash metadata, and a note for users to know that they will need a v2 compatible client for v2 swarms. There should also be a suggestion at upload time that users create hybrid torrents, unless TPB decides to be the adoption driver like they were with magnets.

[RipSHA1]

https://blog.libtorrent.org/2020/09/bittorrent-v2/
backwards compatibility

All new features in BitTorrent v2 that are not backwards compatible have been carefully given new names, to allow them to coexist with the v1 counterparts. Hence, it’s possible to create hybrid torrents. That is, torrents that can participate in both a v1 and a v2 swarm at the same time, serving the same files.

A hybrid torrent has two info-hashes, one v1 SHA-1 hash one (possibly truncated) SHA-256 hash. This forms two swarms, or a segregated swarm. libtorrent marks peers as supporting v2 or not. This information is also relayed via a new peer exchange (PEX) flag.

A hybrid .torrent file includes both piece hashes as well as the tree root hashes for each file.

[LillyLacTac]

So as an uploader, will I now consider creating my magnets as V2, or when i create them will rutorrent automatically make them v2

[Moe]

Depends on the client implementation. You'll likely have the option to make a torrent v1, v2, or both. (you don't create magnets)

[ill88eagle]

So as an uploader, will I now consider creating my magnets as V2, or when i create them will rutorrent automatically make them v2

rutorrent and any other client has to update to support v2 before you can create v2 torrents. That will probably take some time.

Then you should wait for TPB to implement it. That will probably take even longer

Then I guess best option is to create 'hybrid' torrents for backwards compatibility - I suppose it will be a flag you can set like the 'private/public' flag