Fix tunneling of connection when keepalive is set

[balajiv113]

Fixes #3601

[Copilot]

Pull Request Overview

Fix tunneling of connection when keepalive is set by replacing the existing bicopy-based data forwarding with a TCP proxy that preserves keepalive semantics.

• Swap out bicopy.Bicopy for tcpproxy.DialProxy to handle TCP connections
• Update imports from lima/pkg/bicopy to containers/gvisor-tap-vsock/pkg/tcpproxy

Comments suppressed due to low confidence (1)

pkg/portfwd/client.go:36

• This new proxy path for TCP connections lacks dedicated tests; consider adding unit or integration tests to verify tunneling behavior when keepalive is enabled.

	proxy := tcpproxy.DialProxy{DialContext: func(ctx context.Context, _, _ string) (net.Conn, error) {

[balajiv113]

@AkihiroSuda & @jandubois
For now i reverted back to tcpproxy. We can improve bicopy incrementally. Hope its fine.

This works for me. with given reproduction steps

[AkihiroSuda]

Thanks, let's merge this, but we should eventually run a test for this on CI

[nirs]

@AkihiroSuda & @jandubois For now i reverted back to tcpproxy. We can improve bicopy incrementally. Hope its fine.

This works for me. with given reproduction steps

Can you explain what is the issue and how it is solved in tcpproxy? What is missing in bicopy to implement TCP half-close?

Looking at bicopy and tcpproxy, both start goroutines running io.Copy(dot, src), and both call src.CloseRead() and dst.CloseWrite() the goroutine exits. Finally both call src.Close() and dst.Close() at the end.

The only thing missing in biCopy is setting keepalive on both ends, but since we don't set KeepAlivePeriod the keepalive is not set on the net.Con.

Do we have a way to write a test reproducing this issue?

[balajiv113]

I tried to write a test but couldn't but the steps mentioned in the issue is perfectly reproducible