Tolerate send_open() at Closed state?

[vilicvane]

I am having some issue with tunneling TCP using h2, it aborts the connection after the server (usually speedtest servers) resets the connection and h2 trying to send_open().

Not sure if this should be tolerated by h2 or to be handled by my code. I tried to do an early return with a Closed state and it seems to fix my problem.

    pub fn send_open(&mut self, eos: bool) -> Result<(), UserError> {
        let local = Streaming;

        if matches!(self.inner, Inner::Closed(_)) {
            return Ok(());
        }

h2/src/proto/streams/state.rs

Lines 91 to 129 in 77be664

	pub fn send_open(&mut self, eos: bool) -> Result<(), UserError> {
	let local = Streaming;
	self.inner = match self.inner {
	Idle => {
	if eos {
	HalfClosedLocal(AwaitingHeaders)
	} else {
	Open {
	local,
	remote: AwaitingHeaders,
	}
	}
	}
	Open {
	local: AwaitingHeaders,
	remote,
	} => {
	if eos {
	HalfClosedLocal(remote)
	} else {
	Open { local, remote }
	}
	}
	HalfClosedRemote(AwaitingHeaders) | ReservedLocal => {
	if eos {
	Closed(Cause::EndStream)
	} else {
	HalfClosedRemote(local)
	}
	}
	_ => {
	// All other transitions result in a protocol error
	return Err(UserError::UnexpectedFrameType);
	}
	};
	Ok(())
	}

Any suggestions on a proper workaround?

[seanmonstar]

That's not a publicly exposed method outside the crate. What are you actually calling, and what behavior is problematic?

[vilicvane]

I didn't call it directly, it just resulted in aborting the h2 connection in my case.

1. The server receives a request and gets the remote address to connect.
2. It connects the remote and do a bidirectional copy.
3. In this case the speedtest servers close the connection immediately, results in an already closed stream (I suppose) even before h2 internally calls send_open().

Related lines in my codebase:

• Accept stream from h2 connection: https://github.com/vilicvane/plug2proxy/blob/9d160f5eb625e5c29bac2536ed5f6b8336de7b26/src/lib/tunnel/http2/http2_tunnel.rs#L219
• Connect remote and do bidirectional copy: https://github.com/vilicvane/plug2proxy/blob/9d160f5eb625e5c29bac2536ed5f6b8336de7b26/src/lib/out/out.rs#L104