fix(relay): send correct PeerId to client in outbound STOP message

[thomaseizinger]

Description

Previously, the relay server would erroneously send its own PeerId in the STOP message to the client upon an incoming relay connection. This is obviously wrong and results in failed connection upgrades in other implementations.

Notes & open questions

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• A changelog entry has been made in the appropriate crates

[mxinden]

Thanks @thomaseizinger for the patch.

Thanks @MarcoPolo @p-shahi and @maschad for catching it!

[mxinden]

For the record, properly documented in the specification:

the peer field contains a Peer struct with the peer ID of the connection initiator.

https://github.com/libp2p/specs/blob/master/relay/circuit-v2.md#stop-protocol