[client] Destory WG interface on down timeout (#2435)

wait on engine down to not only wait for the interface to be down but completely removed. If the waiting loop reaches the timeout we will trigger an interface destroy. On the up command, it now waits until the engine is fully running before sending the response to the CLI. Includes a small refactor of probes to comply with sonar rules about parameter count in the function call

client/internal/engine.go

@@ -155,10 +155,7 @@ type Engine struct {
 
 	dnsServer dns.Server
 
-	mgmProbe    *Probe
-	signalProbe *Probe
-	relayProbe  *Probe
-	wgProbe     *Probe
+	probes *ProbeHolder
 
 	wgConnWorker sync.WaitGroup
 
@@ -192,9 +189,6 @@ func NewEngine(
 		mobileDep,
 		statusRecorder,
 		nil,
-		nil,
-		nil,
-		nil,
 		checks,
 	)
 }
@@ -208,10 +202,7 @@ func NewEngineWithProbes(
 	config *EngineConfig,
 	mobileDep MobileDependency,
 	statusRecorder *peer.Status,
-	mgmProbe *Probe,
-	signalProbe *Probe,
-	relayProbe *Probe,
-	wgProbe *Probe,
+	probes *ProbeHolder,
 	checks []*mgmProto.Checks,
 ) *Engine {
 
@@ -229,22 +220,20 @@ func NewEngineWithProbes(
 		networkSerial:  0,
 		sshServerFunc:  nbssh.DefaultSSHServer,
 		statusRecorder: statusRecorder,
-		mgmProbe:       mgmProbe,
-		signalProbe:    signalProbe,
-		relayProbe:     relayProbe,
-		wgProbe:        wgProbe,
+		probes:         probes,
 		checks:         checks,
 	}
 }
 
 func (e *Engine) Stop() error {
+	if e == nil {
+		// this seems to be a very odd case but there was the possibility if the netbird down command comes before the engine is fully started
+		log.Debugf("tried stopping engine that is nil")
+		return nil
+	}
 	e.syncMsgMux.Lock()
 	defer e.syncMsgMux.Unlock()
 
-	if e.cancel != nil {
-		e.cancel()
-	}
-
 	// stopping network monitor first to avoid starting the engine again
 	if e.networkMonitor != nil {
 		e.networkMonitor.Stop()
@@ -260,29 +249,21 @@ func (e *Engine) Stop() error {
 	e.clientRoutes = nil
 	e.clientRoutesMu.Unlock()
 
+	if e.cancel != nil {
+		e.cancel()
+	}
+
 	// very ugly but we want to remove peers from the WireGuard interface first before removing interface.
 	// Removing peers happens in the conn.Close() asynchronously
 	time.Sleep(500 * time.Millisecond)
 
 	e.close()
+
 	e.wgConnWorker.Wait()
 
-	maxWaitTime := 5 * time.Second
-	timeout := time.After(maxWaitTime)
+	log.Infof("Engine stopped")
 
-	for {
-		if !e.IsWGIfaceUp() {
-			log.Infof("stopped Netbird Engine")
-			return nil
-		}
-
-		select {
-		case <-timeout:
-			return fmt.Errorf("timeout when waiting for interface shutdown")
-		default:
-			time.Sleep(100 * time.Millisecond)
-		}
-	}
+	return nil
 }
 
 // Start creates a new WireGuard tunnel interface and listens to events from Signal and Management services
@@ -1415,24 +1396,27 @@ func (e *Engine) getRosenpassAddr() string {
 }
 
 func (e *Engine) receiveProbeEvents() {
-	if e.signalProbe != nil {
-		go e.signalProbe.Receive(e.ctx, func() bool {
+	if e.probes == nil {
+		return
+	}
+	if e.probes.SignalProbe != nil {
+		go e.probes.SignalProbe.Receive(e.ctx, func() bool {
 			healthy := e.signal.IsHealthy()
 			log.Debugf("received signal probe request, healthy: %t", healthy)
 			return healthy
 		})
 	}
 
-	if e.mgmProbe != nil {
-		go e.mgmProbe.Receive(e.ctx, func() bool {
+	if e.probes.MgmProbe != nil {
+		go e.probes.MgmProbe.Receive(e.ctx, func() bool {
 			healthy := e.mgmClient.IsHealthy()
 			log.Debugf("received management probe request, healthy: %t", healthy)
 			return healthy
 		})
 	}
 
-	if e.relayProbe != nil {
-		go e.relayProbe.Receive(e.ctx, func() bool {
+	if e.probes.RelayProbe != nil {
+		go e.probes.RelayProbe.Receive(e.ctx, func() bool {
 			healthy := true
 
 			results := append(e.probeSTUNs(), e.probeTURNs()...)
@@ -1451,8 +1435,8 @@ func (e *Engine) receiveProbeEvents() {
 		})
 	}
 
-	if e.wgProbe != nil {
-		go e.wgProbe.Receive(e.ctx, func() bool {
+	if e.probes.WgProbe != nil {
+		go e.probes.WgProbe.Receive(e.ctx, func() bool {
 			log.Debug("received wg probe request")
 
 			for _, peer := range e.peerConns {
@@ -1548,20 +1532,3 @@ func isChecksEqual(checks []*mgmProto.Checks, oChecks []*mgmProto.Checks) bool {
 		return slices.Equal(checks.Files, oChecks.Files)
 	})
 }
-
-func (e *Engine) IsWGIfaceUp() bool {
-	if e == nil || e.wgInterface == nil {
-		return false
-	}
-	iface, err := net.InterfaceByName(e.wgInterface.Name())
-	if err != nil {
-		log.Debugf("failed to get interface by name %s: %v", e.wgInterface.Name(), err)
-		return false
-	}
-
-	if iface.Flags&net.FlagUp != 0 {
-		return true
-	}
-
-	return false
-}