Wrong peer_id after upgrade

[Len Sorensen]

I upgraded from 1.3.12 to 1.3.13 and found out that the peerid being set was still for 1.3.12 (-DE13C0-) rather than 1.3.13 (-DE13D0-). I tracked down why this happened and the fix is simple.

[Len Sorensen]

Patch to fix peer_id when upgrading

[Len Sorensen]

So the problem simply is that the peer_id is generated before the session.state is loaded, which then replaces the peer_id with the old one from the saved session.state, which in my case was from 1.3.12, and then continued to set the user agent to 1.3.13, which then causes some picky trackers to point out that the peer_id and user agent are not in agreement.

Moving the session.state loading just before the peer_id is created solves the problem. Not sure why it is ever saved in the session.state in the first place, unless it is to allow a client to adapt an older saved session on load if going to a new format in a new client version.

[Calum]

What version libtorrent are you using?

[Len Sorensen]

Currently 1.1.1.

[Len Sorensen]

It certainly did seem wrong to generate a peer_id and then overwrite it by loading the saved state immediately afterwards.

[Calum]

There are some substantial change to session settings in 1.1 and this is a by-product of that. There is a new peer_fingerprint setting and it is now stored in session.state so obviously the fingerprint is overwritten upon loading.

Unfortunately your fix is not correct, since it will never load the previous session state.

I have opened an upstream libtorrent ticket:

​https://github.com/arvidn/libtorrent/issues/1519

[Calum]

This will be fixed in next libtorrent release.