BitTorrent v2 protocol & SHA256 via libtorrent 2.0.x series

[teddyrogers]

Tribler 8.0.7, does not support BitTorrent v2 protocol. Attempting to import a v2 SHA256 magnet link gives error:

Error: Failed to retrieve metadata! Error while getting an infohash from magnet: RuntimeError: missing info-hash from URI [libtorrent:22]

Additionally importing a v2 .torrent shows, under the "Size" column, the value "NaN B". Proceeding with the download gives the error message, "Failed to start download!"

Please support the more secure v2 protocol with stronger SHA256 hashing algorithm. This will also reduce the likelihood of MITM attacks within Tribler network. BitTorrent v2 can be implemented via libtorrent 2.0.x series.

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

[absolutep]

It is already in the works = #8371

Eagerly waiting to test it

[teddyrogers]

It is already in the works = #8371

Eagerly waiting to test it

Noted, specifically this is to capture implementation of the v2 protocol and SHA256.

[qstokkink]

With all the other stuff in 8.1.0, I think this is going to be too ambitious for the short term: all the parts of Tribler that deal with torrent infohashes have to be changed (that's a lot of parts!). I'll reschedule this for 8.2.0.

[absolutep]

With all the other stuff in 8.1.0, I think this is going to be too ambitious for the short term: all the parts of Tribler that deal with torrent infohashes have to be changed (that's a lot of parts!). I'll reschedule this for 8.2.0.

does this mean #8371 is not implemented in the build #152?

[qstokkink]

First, important disclaimer: random GitHub builds could potentially contain anything that could completely destroy your Tribler installation. I would very much advise against running them.

That said, yes, that does contain Bittorrent v2. However, the fact that protocol support is implemented, doesn't mean that we use it (yet). So, practically, there should be no difference from using v1.

[qstokkink]

Just "for fun", I decided to check what would happen with the test v2-only torrent. The entire structure of the metainfo in these things is now different. For starters, we depend on the b"length" and the b"files" and these no longer exist.

{
    b 'info': {
        b 'file tree': {
            b '13.Popsy Team - ViP 2.vob.mp4': {
                b '': {
                    b 'length': 27551708,
                    b 'pieces root': b '\x81\xfd?\xec\xc5\xc6\xc3\x9d\xb0V\xe9\x1b|s\xbd{\xb1\x1e\xc2\x01\x1a!\x08F4\xc0\x1b\xfe$\x05\xea\xf9'
                }
            },
            ... (more files with the same structure) ...
        },
        b 'meta version': 2,
        b 'name': b 'bittorrent-v2-test',
        b 'piece length': 4194304
    }
}

This is going to be rough. That said, the hybrid v1 + v2 torrent example does work out-of-the-box now.

[teddyrogers]

@qstokkink delaying BitTorrent v2 protocol & SHA256 implementation to 8.2.0 does not mean migration to libtorrent 2.0.x is delayed?

[qstokkink]

No, it is not delayed. In fact, we already switched to libtorrent 2.0.9. However, using a library and supporting its features are two completely separate things. It mostly means we get under-the-hood support (for example, of hybrid torrents) and we can slow work it into our software. Over time, we'll be able to use/support more and more.