From 810e07a998a6e3986bb3526dc8353f72046d5345 Mon Sep 17 00:00:00 2001
From: JackDoan <me@jackdoan.com>
Date: Wed, 15 Apr 2026 14:01:55 -0500
Subject: [PATCH] nbio for tun

---
 interface.go         | 16 ++++++++--------
 overlay/tun_linux.go |  6 ++----
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/interface.go b/interface.go
index 03542f54..61c8cc3e 100644
--- a/interface.go
+++ b/interface.go
@@ -294,7 +294,7 @@ func (f *Interface) listenOut(i int) {
 		//TODO: Trigger Control to close
 	}
 
-	f.l.Debugf("underlay reader %v is done", i)
+	f.l.Infof("underlay reader %v is done", i)
 }
 
 func (f *Interface) listenIn(reader io.ReadWriteCloser, i int) {
@@ -318,7 +318,7 @@ func (f *Interface) listenIn(reader io.ReadWriteCloser, i int) {
 		f.consumeInsidePacket(packet[:n], fwPacket, nb, out, i, conntrackCache.Get(f.l))
 	}
 
-	f.l.Debugf("overlay reader %v is done", i)
+	f.l.Infof("overlay reader %v is done", i)
 }
 
 func (f *Interface) RegisterConfigChangeCallbacks(c *config.C) {
@@ -493,13 +493,14 @@ func (f *Interface) GetCertState() *CertState {
 }
 
 func (f *Interface) Close() error {
+	var err error
 	f.closed.Store(true)
 
 	// Release the udp readers
-	for _, u := range f.writers {
-		err := u.Close()
+	for i, u := range f.writers {
+		err = u.Close()
 		if err != nil {
-			f.l.WithError(err).Error("Error while closing udp socket")
+			f.l.WithError(err).WithField("writer", i).Error("Error while closing udp socket")
 		}
 	}
 
@@ -508,11 +509,10 @@ func (f *Interface) Close() error {
 		if i == 0 {
 			continue // f.readers[0] is f.inside, which we want to save for last, since it closes other stuff too
 		}
-		if err := r.Close(); err != nil {
-			f.l.WithError(err).Error("Error while closing tun reader")
+		if err = r.Close(); err != nil {
+			f.l.WithError(err).WithField("reader", i).Error("Error while closing tun reader")
 		}
 	}
 
-	// Release the tun device
 	return f.inside.Close()
 }
diff --git a/overlay/tun_linux.go b/overlay/tun_linux.go
index 0fa5a51d..c9586b6b 100644
--- a/overlay/tun_linux.go
+++ b/overlay/tun_linux.go
@@ -26,7 +26,6 @@ import (
 
 type tun struct {
 	io.ReadWriteCloser
-	fd          int
 	Device      string
 	vpnNetworks []netip.Prefix
 	MaxMTU      int
@@ -85,7 +84,7 @@ func newTunFromFd(c *config.C, l *logrus.Logger, deviceFd int, vpnNetworks []net
 }
 
 func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, multiqueue bool) (*tun, error) {
-	fd, err := unix.Open("/dev/net/tun", os.O_RDWR, 0)
+	fd, err := unix.Open("/dev/net/tun", os.O_RDWR|unix.O_NONBLOCK, 0)
 	if err != nil {
 		// If /dev/net/tun doesn't exist, try to create it (will happen in docker)
 		if os.IsNotExist(err) {
@@ -98,7 +97,7 @@ func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, multiqueu
 				return nil, fmt.Errorf("failed to create /dev/net/tun: %w", err)
 			}
 
-			fd, err = unix.Open("/dev/net/tun", os.O_RDWR, 0)
+			fd, err = unix.Open("/dev/net/tun", os.O_RDWR|unix.O_NONBLOCK, 0)
 			if err != nil {
 				return nil, fmt.Errorf("created /dev/net/tun, but still failed: %w", err)
 			}
@@ -136,7 +135,6 @@ func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, multiqueu
 func newTunGeneric(c *config.C, l *logrus.Logger, file *os.File, vpnNetworks []netip.Prefix) (*tun, error) {
 	t := &tun{
 		ReadWriteCloser:           file,
-		fd:                        int(file.Fd()),
 		vpnNetworks:               vpnNetworks,
 		TXQueueLen:                c.GetInt("tun.tx_queue", 500),
 		useSystemRoutes:           c.GetBool("tun.use_system_route_table", false),