global: begin modularization

device/tun.go

@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package device
+
+import (
+	"golang.zx2c4.com/wireguard/tun"
+	"sync/atomic"
+)
+
+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()
+
+	for event := range device.tun.device.Events() {
+		if event&tun.TUNEventMTUUpdate != 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))
+			}
+		}
+
+		if event&tun.TUNEventUp != 0 && !setUp {
+			logInfo.Println("Interface set up")
+			setUp = true
+			device.Up()
+		}
+
+		if event&tun.TUNEventDown != 0 && setUp {
+			logInfo.Println("Interface set down")
+			setUp = false
+			device.Down()
+		}
+	}
+
+	logDebug.Println("Routine: event worker - stopped")
+	device.state.stopping.Done()
+}