1 files changed, 23 insertions, 26 deletions

diff --git a/device/tun.go b/device/tun.go
index 0a3fc79..c85dd50 100644
--- a/device/tun.go
+++ b/device/tun.go
@@ -1,12 +1,12 @@
 /* SPDX-License-Identifier: MIT
  *
- * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
+ * Copyright (C) 2017-2025 WireGuard LLC. All Rights Reserved.
  */
 
 package device
 
 import (
-	"sync/atomic"
+	"fmt"
 
 	"golang.zx2c4.com/wireguard/tun"
 )
@@ -14,43 +14,40 @@ import (
 const DefaultMTU = 1420
 
 func (device *Device) RoutineTUNEventReader() {
-	setUp := false
-	logDebug := device.log.Debug
-	logInfo := device.log.Info
-	logError := device.log.Error
-
-	logDebug.Println("Routine: event worker - started")
-	device.state.starting.Done()
+	device.log.Verbosef("Routine: event worker - started")
 
 	for event := range device.tun.device.Events() {
 		if event&tun.EventMTUUpdate != 0 {
 			mtu, err := device.tun.device.MTU()
-			old := atomic.LoadInt32(&device.tun.mtu)
 			if err != nil {
-				logError.Println("Failed to load updated MTU of device:", err)
-			} else if int(old) != mtu {
-				if mtu+MessageTransportSize > MaxMessageSize {
-					logInfo.Println("MTU updated:", mtu, "(too large)")
-				} else {
-					logInfo.Println("MTU updated:", mtu)
-				}
-				atomic.StoreInt32(&device.tun.mtu, int32(mtu))
+				device.log.Errorf("Failed to load updated MTU of device: %v", err)
+				continue
+			}
+			if mtu < 0 {
+				device.log.Errorf("MTU not updated to negative value: %v", mtu)
+				continue
+			}
+			var tooLarge string
+			if mtu > MaxContentSize {
+				tooLarge = fmt.Sprintf(" (too large, capped at %v)", MaxContentSize)
+				mtu = MaxContentSize
+			}
+			old := device.tun.mtu.Swap(int32(mtu))
+			if int(old) != mtu {
+				device.log.Verbosef("MTU updated: %v%s", mtu, tooLarge)
 			}
 		}
 
-		if event&tun.EventUp != 0 && !setUp {
-			logInfo.Println("Interface set up")
-			setUp = true
+		if event&tun.EventUp != 0 {
+			device.log.Verbosef("Interface up requested")
 			device.Up()
 		}
 
-		if event&tun.EventDown != 0 && setUp {
-			logInfo.Println("Interface set down")
-			setUp = false
+		if event&tun.EventDown != 0 {
+			device.log.Verbosef("Interface down requested")
 			device.Down()
 		}
 	}
 
-	logDebug.Println("Routine: event worker - stopped")
-	device.state.stopping.Done()
+	device.log.Verbosef("Routine: event worker - stopped")
 }