Try the timeout

overlay/tun_linux.go

@@ -66,11 +66,6 @@ type ifreqQLEN struct {
 }
 
 func newTunFromFd(c *config.C, l *logrus.Logger, deviceFd int, vpnNetworks []netip.Prefix) (*tun, error) {
-	err := unix.SetNonblock(deviceFd, true)
-	if err != nil {
-		return nil, err
-	}
-
 	file := os.NewFile(uintptr(deviceFd), "/dev/net/tun")
 
 	t, err := newTunGeneric(c, l, file, vpnNetworks)
@@ -117,11 +112,6 @@ func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, multiqueu
 	}
 	name := strings.Trim(string(req.Name[:]), "\x00")
 
-	err = unix.SetNonblock(fd, true)
-	if err != nil {
-		return nil, err
-	}
-
 	file := os.NewFile(uintptr(fd), "/dev/net/tun")
 	t, err := newTunGeneric(c, l, file, vpnNetworks)
 	if err != nil {
@@ -144,12 +134,7 @@ func newTunGeneric(c *config.C, l *logrus.Logger, file *os.File, vpnNetworks []n
 		l:                         l,
 	}
 
-	err := unix.SetNonblock(t.fd, true)
-	if err != nil {
-		return nil, err
-	}
-
-	err = t.reload(c, true)
+	err := t.reload(c, true)
 	if err != nil {
 		return nil, err
 	}
@@ -244,11 +229,6 @@ func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 		return nil, err
 	}
 
-	err = unix.SetNonblock(fd, true)
-	if err != nil {
-		return nil, err
-	}
-
 	file := os.NewFile(uintptr(fd), "/dev/net/tun")
 
 	return file, nil
@@ -259,6 +239,29 @@ func (t *tun) RoutesFor(ip netip.Addr) routing.Gateways {
 	return r
 }
 
+func (t *tun) Write(b []byte) (int, error) {
+	var nn int
+	maximum := len(b)
+
+	for {
+		n, err := unix.Write(t.fd, b[nn:maximum])
+		if n > 0 {
+			nn += n
+		}
+		if nn == len(b) {
+			return nn, err
+		}
+
+		if err != nil {
+			return nn, err
+		}
+
+		if n == 0 {
+			return nn, io.ErrUnexpectedEOF
+		}
+	}
+}
+
 func (t *tun) deviceBytes() (o [16]byte) {
 	for i, c := range t.Device {
 		o[i] = byte(c)