Give bind its own wait group

In a waitgroup, all waits must come after all adds

conn.go

@@ -75,6 +75,7 @@ func unsafeCloseBind(device *Device) error {
 		err = netc.bind.Close()
 		netc.bind = nil
 	}
+	netc.stopping.Wait()
 	return err
 }
 
@@ -162,10 +163,11 @@ func (device *Device) BindUpdate() error {
 
 		// start receiving routines
 
-		device.state.starting.Add(ConnRoutineNumber)
-		device.state.stopping.Add(ConnRoutineNumber)
+		device.net.starting.Add(ConnRoutineNumber)
+		device.net.stopping.Add(ConnRoutineNumber)
 		go device.RoutineReceiveIncoming(ipv4.Version, netc.bind)
 		go device.RoutineReceiveIncoming(ipv6.Version, netc.bind)
+		device.net.starting.Wait()
 
 		device.log.Debug.Println("UDP bind has been updated")
 	}

device.go

@@ -35,6 +35,8 @@ type Device struct {
 	}
 
 	net struct {
+		starting sync.WaitGroup
+		stopping sync.WaitGroup
 		mutex  sync.RWMutex
 		bind   Bind   // bind interface
 		port   uint16 // listening port

receive.go

@@ -125,11 +125,11 @@ func (device *Device) RoutineReceiveIncoming(IP int, bind Bind) {
 	logDebug := device.log.Debug
 	defer func() {
 		logDebug.Println("Routine: receive incoming IPv" + strconv.Itoa(IP) + " - stopped")
-		device.state.stopping.Done()
+		device.net.stopping.Done()
 	}()
 
 	logDebug.Println("Routine: receive incoming IPv" + strconv.Itoa(IP) + " - starting")
-	device.state.starting.Done()
+	device.net.starting.Done()
 
 	// receive datagrams until conn is closed