tcpproxy: support half-close with gvisor conns (#46)

raggi · web-flow · commit 48c7e53d7ac4 · 2025-01-21T10:32:18.000-08:00
gonet.TCPConn implements CloseRead and CloseWrite, but it is not a net.TCPConn. Use an interface to look for CloseRead and CloseWrite so that they are called on gonet.TCPConn. Updates tailscale/corp#25169 Signed-off-by: James Tucker <jftucker@gmail.com>
diff --git a/tcpproxy.go b/tcpproxy.go
@@ -355,16 +355,21 @@ func tcpConn(c net.Conn) (t *net.TCPConn, ok bool) {
 	return nil, false
 }
 
+type closeReader interface{ CloseRead() error }
+type closeWriter interface{ CloseWrite() error }
+
 func goCloseConn(c net.Conn) { go c.Close() }
 
 func closeRead(c net.Conn) {
-	if c, ok := tcpConn(c); ok {
+	// prefer the interfaces, for compatibility with e.g. gvisor/netstack.
+	if c, ok := UnderlyingConn(c).(closeReader); ok {
 		c.CloseRead()
 	}
 }
 
 func closeWrite(c net.Conn) {
-	if c, ok := tcpConn(c); ok {
+	// prefer the interfaces, for compatibility with e.g. gvisor/netstack.
+	if c, ok := UnderlyingConn(c).(closeWriter); ok {
 		c.CloseWrite()
 	}
 }

Original file line number	Diff line number	Diff line change
`@@ -355,16 +355,21 @@ func tcpConn(c net.Conn) (t *net.TCPConn, ok bool) {`
`355`	`355`	`return nil, false`
`356`	`356`	`}`
`357`	`357`
	`358`	`+type closeReader interface{ CloseRead() error }`
	`359`	`+type closeWriter interface{ CloseWrite() error }`
	`360`	`+`
`358`	`361`	`func goCloseConn(c net.Conn) { go c.Close() }`
`359`	`362`
`360`	`363`	`func closeRead(c net.Conn) {`
`361`		`- if c, ok := tcpConn(c); ok {`
	`364`	`+ // prefer the interfaces, for compatibility with e.g. gvisor/netstack.`
	`365`	`+ if c, ok := UnderlyingConn(c).(closeReader); ok {`
`362`	`366`	`c.CloseRead()`
`363`	`367`	`}`
`364`	`368`	`}`
`365`	`369`
`366`	`370`	`func closeWrite(c net.Conn) {`
`367`		`- if c, ok := tcpConn(c); ok {`
	`371`	`+ // prefer the interfaces, for compatibility with e.g. gvisor/netstack.`
	`372`	`+ if c, ok := UnderlyingConn(c).(closeWriter); ok {`
`368`	`373`	`c.CloseWrite()`
`369`	`374`	`}`
`370`	`375`	`}`