identify: Exchange fails with go-libp2p over QUIC when initialy closing

[mxinden]

To receive a remote's identify information one opens a stream and waits for the remote to send the identify payload in that stream.

When connecting to a go-libp2p node over a QUIC connection, identify exchanges fail.

rust-libp2p/protocols/identify/src/protocol.rs

Lines 192 to 196 in 68d0f88

	async fn recv<T>(mut socket: T) -> Result<Info, UpgradeError>
	where
	T: AsyncRead + AsyncWrite + Unpin,
	{
	socket.close().await?;

Changing the above to flush instead of close resolves the issue. Note that flushing instead of no action at all is needed in case multistream-select V1Lazy is used where the multistream-select message is only send on the stream once userdata is send or it is flushed.

Occurs with the rust-libp2p punchr client when connecting to go-libp2p IPFS nodes.

Opening with little details for now to have a central place to track. @elenaf9 in case you need more details, let me know.

[mxinden]

Note that flushing instead of no action at all is needed in case multistream-select V1Lazy is used where the multistream-select message is only send on the stream once userdata is send or it is flushed.

This is likely incorrect. That is, a read should be enough according to the below:

rust-libp2p/misc/multistream-select/src/negotiated.rs

Lines 45 to 46 in 68d0f88

	/// Reading from a `Negotiated` I/O stream that still has pending negotiation
	/// protocol data to send implicitly triggers flushing of all yet unsent data.

[dignifiedquire]

Might this be the reason I am not able to get a single hole punch to work with the punchr setup + rust-libp2p-client?

Edit: Almost no connections, there is like 1 per hour or so at most that succeeds (been running for a couple of days now)

[mxinden]

@dignifiedquire small update on rust-libp2p punchr. With a couple of upcoming patches I am able to achieve ~50% success rate.

• This patch, i.e. flush instead of close, or even none of either.
• fix(quic): Identify /quic as QUIC address #3288
• rust-libp2p punchr to use keep_alive::Behaviour to await identify.
• rust-libp2p punchr to prioritize QUIC connections to bootstrap nodes to learn QUIC external addresses.

While 50% is still behind go-libp2p, I would consider this a good step forward.