From 3fa2f327378df0a2412a058bc03a3ebdda16a8b8 Mon Sep 17 00:00:00 2001
From: soypat <graded.sp@gmail.com>
Date: Fri, 24 Oct 2025 18:26:59 -0300
Subject: [PATCH] fix timewait not counting as closed state in listen open; add
 second part to test

---
 tcp/control.go      |  2 +-
 x/xnet/xnet_test.go | 32 ++++++++++++++++++++++++--------
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/tcp/control.go b/tcp/control.go
index ce2e465..2810e2f 100644
--- a/tcp/control.go
+++ b/tcp/control.go
@@ -148,7 +148,7 @@ type recvSpace struct {
 // To open an active connection use [ControlBlock.Send] with a segment generated with [ClientSynSegment].
 func (tcb *ControlBlock) Open(iss Value, wnd Size) (err error) {
 	switch {
-	case tcb._state != StateClosed && tcb._state != StateListen:
+	case tcb._state != StateClosed && tcb._state != StateTimeWait:
 		err = errNeedClosedTCBToOpen
 	case wnd > math.MaxUint16:
 		err = errWindowTooLarge
diff --git a/x/xnet/xnet_test.go b/x/xnet/xnet_test.go
index 48becc5..5766537 100644
--- a/x/xnet/xnet_test.go
+++ b/x/xnet/xnet_test.go
@@ -17,7 +17,7 @@ const (
 	finack = tcp.FlagFIN | tcp.FlagACK
 )
 
-func TestABC(t *testing.T) {
+func TestStackAsyncTCP(t *testing.T) {
 	const seed = 1234
 	const MTU = 1500
 	var mac = [6]byte{0x02, 0x00, 0x00, 0x00, 0x00, 0x01}
@@ -47,6 +47,8 @@ func TestABC(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	client.SetGateway6(sv.HardwareAddress())
+	sv.SetGateway6(client.HardwareAddress())
 
 	const svPort = 80
 	var svconn tcp.Conn
@@ -58,11 +60,6 @@ func TestABC(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	err = sv.ListenTCP(&svconn, svPort)
-	if err != nil {
-		t.Fatal(err)
-	}
-
 	var clconn tcp.Conn
 	err = clconn.Configure(tcp.ConnConfig{
 		RxBuf:             make([]byte, MTU),
@@ -72,9 +69,12 @@ func TestABC(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	client.SetGateway6(sv.HardwareAddress())
-	sv.SetGateway6(client.HardwareAddress())
 
+	// Attach server and client connections to stacks.
+	err = sv.ListenTCP(&svconn, svPort)
+	if err != nil {
+		t.Fatal(err)
+	}
 	err = client.DialTCP(&clconn, 1337, netip.AddrPortFrom(sv.Addr(), svPort))
 	if err != nil {
 		t.Fatal(err)
@@ -87,6 +87,22 @@ func TestABC(t *testing.T) {
 	tst.TestTCPHandshake(&client, &sv)
 	tst.TestTCPEstablishedSingleData(&client, &sv, &clconn, &svconn, sendData)
 	tst.TestTCPClose(&client, &sv, &clconn, &svconn)
+
+	// Switch handles around, now server will be client and they will be registered to
+	// a different stack.
+	svconn, clconn = clconn, svconn
+	err = sv.ListenTCP(&svconn, svPort)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = client.DialTCP(&clconn, 1234, netip.AddrPortFrom(sv.Addr(), svPort))
+	if err != nil {
+		t.Fatal(err)
+	}
+	sendData = []byte("olleh")
+	tst.TestTCPHandshake(&client, &sv)
+	tst.TestTCPEstablishedSingleData(&client, &sv, &clconn, &svconn, sendData)
+	tst.TestTCPClose(&client, &sv, &clconn, &svconn)
 }
 
 type tester struct {