Close frame for closed substream

[divagant-martian]

Description

On latest versions (around ~0.3.0) we started getting this error

Oct 26 22:24:57.797 DEBG RPC Error
err: IO Error: Protocol error: Received `Close` frame for closed substream.
protocol: metadata
service: libp2p

This debug msg is printed, as far as I can tell, exclusively on metadata messages, but there is also this log:

Oct 26 22:32:45.009 DEBG Connection closed
connections: 0
cause: Some(IO(Custom { kind: Other, error: "Protocol error: Received `Close` frame for closed substream." }))
service: libp2p

This means this error is killing connections with peers, most likely quite rapidly. I expect this to affect head syncing the most

We should investigate what's the source of these errors and check if they really should be killing connections with a peer

Version

master on 92c8eba

Present Behaviour

Connections are killed by this errors

Expected Behaviour

Probably ignore the error

Steps to resolve

detective tasks

[romanb]

Does this error occur

a) between communicating nodes that all use the same rust-libp2p version?
b) between communicating nodes that use different rust-libp2p versions?
c) between nodes using rust-libp2p and nodes using other libp2p implementations?

If a), it may indicate a bug in rust-libp2p. If b) it may indicate that older versions of rust-libp2p potentially send duplicate Close frames and the newer version thus needs to be more lenient to maintain backwards-compatibility. If c) it may indicate that rust-libp2p needs to be more lenient in accepting duplicate Close frames because other implementations may send them.

cc @mxinden

[divagant-martian]

Thanks @romanb after checking some more this only happens with a golang client, so I guess c it is
EDIT: May worth noting that checking the versions of the other client that I have registered on my logs for these errors (around 2k logs, not much, with 16 different identifiable versions) shows they haven't changed anything related to substream management

[romanb]

Thanks for the feedback. libp2p-mplex-0.23.1 has been published which should resolve this problem by ignoring duplicate Close frames, as was the case in earlier versions.

[divagant-martian]

Hey @romanb, thanks a lot. I'll close after we can upgrade and test