Gracefully conn worker shutdown (#2022)

Because the connWorker are operating with the e.peerConns list we must ensure all workers exited before we modify the content of the e.peerConns list.
If we do not do that the engine will start new connWorkers for the exists ones, and they start connection for the same peers in parallel.

client/internal/engine_test.go

@@ -229,6 +229,7 @@ func TestEngine_UpdateNetworkMap(t *testing.T) {
 		t.Fatal(err)
 	}
 	engine.udpMux = bind.NewUniversalUDPMuxDefault(bind.UniversalUDPMuxParams{UDPConn: conn})
+	engine.ctx = ctx
 
 	type testCase struct {
 		name       string
@@ -408,6 +409,7 @@ func TestEngine_Sync(t *testing.T) {
 		WgPrivateKey: key,
 		WgPort:       33100,
 	}, MobileDependency{}, peer.NewRecorder("https://mgm"))
+	engine.ctx = ctx
 
 	engine.dnsServer = &dns.MockServer{
 		UpdateDNSServerFunc: func(serial uint64, update nbdns.Config) error { return nil },
@@ -566,6 +568,7 @@ func TestEngine_UpdateNetworkMapWithRoutes(t *testing.T) {
 				WgPrivateKey: key,
 				WgPort:       33100,
 			}, MobileDependency{}, peer.NewRecorder("https://mgm"))
+			engine.ctx = ctx
 			newNet, err := stdnet.NewNet()
 			if err != nil {
 				t.Fatal(err)
@@ -735,6 +738,8 @@ func TestEngine_UpdateNetworkMapWithDNSUpdate(t *testing.T) {
 				WgPrivateKey: key,
 				WgPort:       33100,
 			}, MobileDependency{}, peer.NewRecorder("https://mgm"))
+			engine.ctx = ctx
+
 			newNet, err := stdnet.NewNet()
 			if err != nil {
 				t.Fatal(err)
@@ -1003,7 +1008,9 @@ func createEngine(ctx context.Context, cancel context.CancelFunc, setupKey strin
 		WgPort:       wgPort,
 	}
 
-	return NewEngine(ctx, cancel, signalClient, mgmtClient, conf, MobileDependency{}, peer.NewRecorder("https://mgm")), nil
+	e, err := NewEngine(ctx, cancel, signalClient, mgmtClient, conf, MobileDependency{}, peer.NewRecorder("https://mgm")), nil
+	e.ctx = ctx
+	return e, err
 }
 
 func startSignal() (*grpc.Server, string, error) {