From 4b7ace59a09c894036add7ed35031e494a1d5268 Mon Sep 17 00:00:00 2001
From: JiHwan Oh <sapindus.hwan@gmail.com>
Date: Fri, 28 Nov 2025 21:14:12 +0900
Subject: [PATCH] refactor(tun): use context for packet handling and cleanup

Signed-off-by: JiHwan Oh <sapindus.hwan@gmail.com>
---
 tun/netstack/tun.go | 62 ++++++++++++++++++++-------------------------
 1 file changed, 27 insertions(+), 35 deletions(-)

diff --git a/tun/netstack/tun.go b/tun/netstack/tun.go
index a7aec9e82..9611dc4e8 100644
--- a/tun/netstack/tun.go
+++ b/tun/netstack/tun.go
@@ -40,14 +40,14 @@ import (
 )
 
 type netTun struct {
-	ep             *channel.Endpoint
-	stack          *stack.Stack
-	events         chan tun.Event
-	notifyHandle   *channel.NotificationHandle
-	incomingPacket chan *buffer.View
-	mtu            int
-	dnsServers     []netip.Addr
-	hasV4, hasV6   bool
+	ep           *channel.Endpoint
+	stack        *stack.Stack
+	events       chan tun.Event
+	ctx          context.Context
+	cancel       context.CancelFunc
+	mtu          int
+	dnsServers   []netip.Addr
+	hasV4, hasV6 bool
 }
 
 type Net netTun
@@ -58,20 +58,23 @@ func CreateNetTUN(localAddresses, dnsServers []netip.Addr, mtu int) (tun.Device,
 		TransportProtocols: []stack.TransportProtocolFactory{tcp.NewProtocol, udp.NewProtocol, icmp.NewProtocol6, icmp.NewProtocol4},
 		HandleLocal:        true,
 	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+
 	dev := &netTun{
-		ep:             channel.New(1024, uint32(mtu), ""),
-		stack:          stack.New(opts),
-		events:         make(chan tun.Event, 10),
-		incomingPacket: make(chan *buffer.View),
-		dnsServers:     dnsServers,
-		mtu:            mtu,
+		ep:         channel.New(1024, uint32(mtu), ""),
+		stack:      stack.New(opts),
+		events:     make(chan tun.Event, 10),
+		ctx:        ctx,
+		cancel:     cancel,
+		dnsServers: dnsServers,
+		mtu:        mtu,
 	}
 	sackEnabledOpt := tcpip.TCPSACKEnabled(true) // TCP SACK is disabled by default
 	tcpipErr := dev.stack.SetTransportProtocolOption(tcp.ProtocolNumber, &sackEnabledOpt)
 	if tcpipErr != nil {
 		return nil, nil, fmt.Errorf("could not enable TCP SACK: %v", tcpipErr)
 	}
-	dev.notifyHandle = dev.ep.AddNotify(dev)
 	tcpipErr = dev.stack.CreateNIC(1, dev.ep)
 	if tcpipErr != nil {
 		return nil, nil, fmt.Errorf("CreateNIC: %v", tcpipErr)
@@ -121,11 +124,12 @@ func (tun *netTun) Events() <-chan tun.Event {
 }
 
 func (tun *netTun) Read(buf [][]byte, sizes []int, offset int) (int, error) {
-	view, ok := <-tun.incomingPacket
-	if !ok {
+	pkb := tun.ep.ReadContext(tun.ctx)
+	if pkb == nil {
 		return 0, os.ErrClosed
 	}
-
+	view := pkb.ToView()
+	pkb.DecRef()
 	n, err := view.Read(buf[0][offset:])
 	if err != nil {
 		return 0, err
@@ -135,6 +139,10 @@ func (tun *netTun) Read(buf [][]byte, sizes []int, offset int) (int, error) {
 }
 
 func (tun *netTun) Write(buf [][]byte, offset int) (int, error) {
+	if tun.ctx.Err() != nil {
+		return 0, os.ErrClosed
+	}
+
 	for _, buf := range buf {
 		packet := buf[offset:]
 		if len(packet) == 0 {
@@ -154,32 +162,16 @@ func (tun *netTun) Write(buf [][]byte, offset int) (int, error) {
 	return len(buf), nil
 }
 
-func (tun *netTun) WriteNotify() {
-	pkt := tun.ep.Read()
-	if pkt == nil {
-		return
-	}
-
-	view := pkt.ToView()
-	pkt.DecRef()
-
-	tun.incomingPacket <- view
-}
-
 func (tun *netTun) Close() error {
+	tun.cancel()
 	tun.stack.RemoveNIC(1)
 	tun.stack.Close()
-	tun.ep.RemoveNotify(tun.notifyHandle)
 	tun.ep.Close()
 
 	if tun.events != nil {
 		close(tun.events)
 	}
 
-	if tun.incomingPacket != nil {
-		close(tun.incomingPacket)
-	}
-
 	return nil
 }