Erratic behavior when SSH-ing with IPv6 hosts

[RaitoBezarius]

I'm trying to use it with IPv6 and I notice multiple erratic behaviors with the PTY initialization and stuff, here's an log of the client in verbose:

11:20PM DBG dialing QUIC host at [snip]:8443
2024/01/25 23:20:57 failed to sufficiently increase receive buffer size (was: 208 kiB, wanted: 2048 kiB, got: 416 kiB). See https://github.com/quic-go/quic-go/wiki/UDP-Buffer-Sizes for details.
11:20PM DBG QUIC handshake complete
11:20PM DBG try the following Identity: pubkey-identity: ALG=RS256
11:20PM DBG send CONNECT request to the server
11:20PM DBG opened new session channel
11:20PM DBG sent pty request for session
11:20PM DBG sent shell request
11:20PM DBG received data #                                                                                                                                                                                                                   
Could not get message: INTERNAL_ERROR (local): write udp [::]:34297->[snip]:8443: sendmsg: invalid argument

After this crash, the terminal is broken because I suppose it was not reset properly on the exit.

[mpiraux]

Could you reproduce the log and trace the network system calls ? I use strace for that, and strace -e trace=network your_client_ssh3_bin ... is probably what you're looking for. That way we can observe the arguments passed to sendmsg and find the root cause. Thanks for filing this.