Added missing IF index check

src/conn.go

@@ -5,9 +5,9 @@ import (
 )
 
 func updateUDPConn(device *Device) error {
-	var err error
 	netc := &device.net
 	netc.mutex.Lock()
+	defer netc.mutex.Unlock()
 
 	// close existing connection
 
@@ -18,15 +18,23 @@ func updateUDPConn(device *Device) error {
 	// open new connection
 
 	if device.tun.isUp.Get() {
+
+		// listen on new address
+
 		conn, err := net.ListenUDP("udp", netc.addr)
-		if err == nil {
-			netc.conn = conn
-			signalSend(device.signal.newUDPConn)
+		if err != nil {
+			return err
 		}
+
+		// retrieve port (may have been chosen by kernel)
+
+		addr := conn.LocalAddr()
+		netc.conn = conn
+		netc.addr, _ = net.ResolveUDPAddr(addr.Network(), addr.String())
+		signalSend(device.signal.newUDPConn)
 	}
 
-	netc.mutex.Unlock()
-	return err
+	return nil
 }
 
 func closeUDPConn(device *Device) {

src/device.go

@@ -196,15 +196,19 @@ func (device *Device) RoutineTUNEventReader() {
 		}
 
 		if event&TUNEventUp != 0 {
-			device.tun.isUp.Set(true)
-			updateUDPConn(device)
-			logInfo.Println("Interface set up")
+			if !device.tun.isUp.Get() {
+				device.tun.isUp.Set(true)
+				updateUDPConn(device)
+				logInfo.Println("Interface set up")
+			}
 		}
 
 		if event&TUNEventDown != 0 {
-			device.tun.isUp.Set(false)
-			closeUDPConn(device)
-			logInfo.Println("Interface set down")
+			if device.tun.isUp.Get() {
+				device.tun.isUp.Set(false)
+				closeUDPConn(device)
+				logInfo.Println("Interface set down")
+			}
 		}
 	}
 }

src/tun_linux.go

@@ -50,10 +50,10 @@ const (
 
 type NativeTun struct {
 	fd     *os.File
-	index  int
-	name   string
+	index  int32         // if index
+	name   string        // name of interface
 	errors chan error    // async error handling
-	events chan TUNEvent //
+	events chan TUNEvent // device related events
 }
 
 func (tun *NativeTun) RoutineNetlinkListener() {
@@ -86,6 +86,11 @@ func (tun *NativeTun) RoutineNetlinkListener() {
 			case unix.RTM_NEWLINK:
 				info := *(*unix.IfInfomsg)(unsafe.Pointer(&remain[unix.SizeofNlMsghdr]))
 
+				if info.Index != tun.index {
+					// not our interface
+					continue
+				}
+
 				if info.Flags&unix.IFF_RUNNING != 0 {
 					tun.events <- TUNEventUp
 				}
@@ -112,12 +117,12 @@ func (tun *NativeTun) Name() string {
 	return tun.name
 }
 
-func toInt32(val []byte) int {
+func toInt32(val []byte) int32 {
 	n := binary.LittleEndian.Uint32(val[:4])
 	if n >= (1 << 31) {
-		return int(n-(1<<31)) - (1 << 31)
+		return -int32(^n) - 1
 	}
-	return int(n)
+	return int32(n)
 }
 
 func getDummySock() (int, error) {
@@ -128,7 +133,7 @@ func getDummySock() (int, error) {
 	)
 }
 
-func getIFIndex(name string) (int, error) {
+func getIFIndex(name string) (int32, error) {
 	fd, err := getDummySock()
 	if err != nil {
 		return 0, err
@@ -288,7 +293,7 @@ func CreateTUN(name string) (TUNDevice, error) {
 		errors: make(chan error, 5),
 	}
 
-	// fetch IF index
+	// start event listener
 
 	device.index, err = getIFIndex(device.name)
 	if err != nil {
@@ -299,7 +304,5 @@ func CreateTUN(name string) (TUNDevice, error) {
 
 	// set default MTU
 
-	fmt.Println(device)
-
 	return device, device.setMTU(DefaultMTU)
 }