From 236e84c4d6ba94a123a40d7c857e3dac1ccc6830 Mon Sep 17 00:00:00 2001
From: Spike Curtis <spike@coder.com>
Date: Mon, 9 Oct 2023 19:41:26 +0400
Subject: [PATCH] feat: add logging for forwarded TCP connections

part of #7963

log TCP connections as they are forwarded by gVisor
---
 tailnet/conn.go | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tailnet/conn.go b/tailnet/conn.go
index 8808fab775..358241108d 100644
--- a/tailnet/conn.go
+++ b/tailnet/conn.go
@@ -943,7 +943,8 @@ func (c *Conn) DialContextUDP(ctx context.Context, ipp netip.AddrPort) (*gonet.U
 	return c.netStack.DialContextUDP(ctx, ipp)
 }
 
-func (c *Conn) forwardTCP(_, dst netip.AddrPort) (handler func(net.Conn), opts []tcpip.SettableSocketOption, intercept bool) {
+func (c *Conn) forwardTCP(src, dst netip.AddrPort) (handler func(net.Conn), opts []tcpip.SettableSocketOption, intercept bool) {
+	logger := c.logger.Named("tcp").With(slog.F("src", src.String()), slog.F("dst", dst.String()))
 	c.mutex.Lock()
 	ln, ok := c.listeners[listenKey{"tcp", "", fmt.Sprint(dst.Port())}]
 	c.mutex.Unlock()
@@ -961,10 +962,14 @@ func (c *Conn) forwardTCP(_, dst netip.AddrPort) (handler func(net.Conn), opts [
 		defer t.Stop()
 		select {
 		case ln.conn <- conn:
+			logger.Info(context.Background(), "accepted connection")
 			return
 		case <-ln.closed:
+			logger.Info(context.Background(), "listener closed; closing connection")
 		case <-c.closed:
+			logger.Info(context.Background(), "tailnet closed; closing connection")
 		case <-t.C:
+			logger.Info(context.Background(), "listener timed out accepting; closing connection")
 		}
 		_ = conn.Close()
 	}, opts, true