Better error handling for group calls.

app/src/main/java/org/thoughtcrime/securesms/WebRtcCallActivity.java

@@ -141,9 +141,9 @@ public class WebRtcCallActivity extends BaseActivity implements SafetyNumberChan
       EventBus.getDefault().unregister(this);
     }
 
-    if (!viewModel.isCallingStarted()) {
+    if (!viewModel.isCallStarting()) {
       CallParticipantsState state = viewModel.getCallParticipantsState().getValue();
-      if (state != null && state.getCallState() == WebRtcViewModel.State.CALL_PRE_JOIN) {
+      if (state != null && state.getCallState().isPreJoinOrNetworkUnavailable()) {
         finish();
       }
     }
@@ -156,9 +156,9 @@ public class WebRtcCallActivity extends BaseActivity implements SafetyNumberChan
 
     EventBus.getDefault().unregister(this);
 
-    if (!viewModel.isCallingStarted()) {
+    if (!viewModel.isCallStarting()) {
       CallParticipantsState state = viewModel.getCallParticipantsState().getValue();
-      if (state != null && state.getCallState() == WebRtcViewModel.State.CALL_PRE_JOIN) {
+      if (state != null && state.getCallState().isPreJoinOrNetworkUnavailable()) {
         Intent intent = new Intent(this, WebRtcCallService.class);
         intent.setAction(WebRtcCallService.ACTION_CANCEL_PRE_JOIN_CALL);
         startService(intent);
@@ -471,7 +471,6 @@ public class WebRtcCallActivity extends BaseActivity implements SafetyNumberChan
   private void handleServerFailure() {
     EventBus.getDefault().removeStickyEvent(WebRtcViewModel.class);
     callScreen.setStatus(getString(R.string.RedPhone_network_failed));
-    delayedFinish();
   }
 
   private void handleNoSuchUser(final @NonNull WebRtcViewModel event) {
@@ -529,7 +528,7 @@ public class WebRtcCallActivity extends BaseActivity implements SafetyNumberChan
             .putExtra(WebRtcCallService.EXTRA_RECIPIENT_IDS, RecipientId.toSerializedList(changedRecipients));
       startService(intent);
     } else {
-      startCall(state.getLocalParticipant().isVideoEnabled());
+      viewModel.startCall(state.getLocalParticipant().isVideoEnabled());
     }
   }
 
@@ -540,7 +539,7 @@ public class WebRtcCallActivity extends BaseActivity implements SafetyNumberChan
   public void onCanceled() {
     CallParticipantsState state = viewModel.getCallParticipantsState().getValue();
     if (state != null && state.getGroupCallState().isNotIdle()) {
-      if (state.getCallState() == WebRtcViewModel.State.CALL_PRE_JOIN) {
+      if (state.getCallState().isPreJoinOrNetworkUnavailable()) {
         Intent intent = new Intent(this, WebRtcCallService.class);
         intent.setAction(WebRtcCallService.ACTION_CANCEL_PRE_JOIN_CALL);
         startService(intent);

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/WebRtcCallView.java

@@ -96,6 +96,7 @@ public class WebRtcCallView extends FrameLayout {
   private TextView                      participantCount;
   private Stub<FrameLayout>             groupCallSpeakerHint;
   private Stub<View>                    groupCallFullStub;
+  private View                          errorButton;
   private int                           pagerBottomMarginDp;
   private boolean                       controlsVisible = true;
 
@@ -151,6 +152,7 @@ public class WebRtcCallView extends FrameLayout {
     callParticipantsRecycler      = findViewById(R.id.call_screen_participants_recycler);
     toolbar                       = findViewById(R.id.call_screen_toolbar);
     startCall                     = findViewById(R.id.call_screen_start_call_start_call);
+    errorButton                   = findViewById(R.id.call_screen_error_cancel);
     groupCallSpeakerHint          = new Stub<>(findViewById(R.id.call_screen_group_call_speaker_hint));
     groupCallFullStub             = new Stub<>(findViewById(R.id.group_call_call_full_view));
 
@@ -227,6 +229,12 @@ public class WebRtcCallView extends FrameLayout {
 
     int statusBarHeight = ViewUtil.getStatusBarHeight(this);
     statusBarGuideline.setGuidelineBegin(statusBarHeight);
+
+    errorButton.setOnClickListener(v -> {
+      if (controlsListener != null) {
+        controlsListener.onCancelStartCall();
+      }
+    });
   }
 
   @Override
@@ -426,6 +434,11 @@ public class WebRtcCallView extends FrameLayout {
       startCall.setEnabled(webRtcControls.isStartCallEnabled());
     }
 
+    if (webRtcControls.displayErrorControls()) {
+      visibleViewSet.add(footerGradient);
+      visibleViewSet.add(errorButton);
+    }
+
     if (webRtcControls.displayGroupCallFull()) {
       groupCallFullStub.get().setVisibility(View.VISIBLE);
       ((TextView) groupCallFullStub.get().findViewById(R.id.group_call_call_full_message)).setText(webRtcControls.getGroupCallFullMessage(getContext()));

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/WebRtcCallViewModel.java

@@ -56,8 +56,8 @@ public class WebRtcCallViewModel extends ViewModel {
   private boolean               answerWithVideoAvailable  = false;
   private Runnable              elapsedTimeRunnable       = this::handleTick;
   private boolean               canEnterPipMode           = false;
-  private List<CallParticipant> previousParticipantsList  = Collections.emptyList();
+  private List<CallParticipant> previousParticipantsList = Collections.emptyList();
-  private boolean               callingStarted            = false;
+  private boolean               callStarting             = false;
 
   private final WebRtcCallRepository repository = new WebRtcCallRepository(ApplicationDependencies.getApplication());
 
@@ -113,8 +113,8 @@ public class WebRtcCallViewModel extends ViewModel {
     return answerWithVideoAvailable;
   }
 
-  public boolean isCallingStarted() {
+  public boolean isCallStarting() {
-    return callingStarted;
+    return callStarting;
   }
 
   @MainThread
@@ -141,7 +141,10 @@ public class WebRtcCallViewModel extends ViewModel {
 
   @MainThread
   public void updateFromWebRtcViewModel(@NonNull WebRtcViewModel webRtcViewModel, boolean enableVideo) {
-    canEnterPipMode = webRtcViewModel.getState() != WebRtcViewModel.State.CALL_PRE_JOIN;
+    canEnterPipMode = !webRtcViewModel.getState().isPreJoinOrNetworkUnavailable();
+    if (callStarting && webRtcViewModel.getState().isPassedPreJoin()) {
+      callStarting = false;
+    }
 
     CallParticipant localParticipant = webRtcViewModel.getLocalParticipant();
 
@@ -232,6 +235,9 @@ public class WebRtcCallViewModel extends ViewModel {
       case CALL_DISCONNECTED:
         callState = WebRtcControls.CallState.ENDING;
         break;
+      case NETWORK_FAILURE:
+        callState = WebRtcControls.CallState.ERROR;
+        break;
       default:
         callState = WebRtcControls.CallState.ONGOING;
     }
@@ -309,7 +315,7 @@ public class WebRtcCallViewModel extends ViewModel {
   }
 
   public void startCall(boolean isVideoCall) {
-    callingStarted = true;
+    callStarting = true;
     Recipient recipient = getRecipient().get();
     if (recipient.isGroup()) {
       repository.getIdentityRecords(recipient, identityRecords -> {

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/WebRtcControls.java

@@ -51,6 +51,10 @@ public final class WebRtcControls {
     this.participantLimit             = participantLimit;
   }
 
+  boolean displayErrorControls() {
+    return isError();
+  }
+
   boolean displayStartCallControls() {
     return isPreJoin();
   }
@@ -145,6 +149,10 @@ public final class WebRtcControls {
     return audioOutput;
   }
 
+  private boolean isError() {
+    return callState == CallState.ERROR;
+  }
+
   private boolean isPreJoin() {
     return callState == CallState.PRE_JOIN;
   }
@@ -167,6 +175,7 @@ public final class WebRtcControls {
 
   public enum CallState {
     NONE,
+    ERROR,
     PRE_JOIN,
     INCOMING,
     OUTGOING,

app/src/main/java/org/thoughtcrime/securesms/events/WebRtcViewModel.java

@@ -46,6 +46,14 @@ public class WebRtcViewModel {
              this == NO_SUCH_USER          ||
              this == UNTRUSTED_IDENTITY;
     }
+
+    public boolean isPreJoinOrNetworkUnavailable() {
+      return this == CALL_PRE_JOIN || this == NETWORK_FAILURE;
+    }
+
+    public boolean isPassedPreJoin() {
+      return this.ordinal() > CALL_PRE_JOIN.ordinal();
+    }
   }
 
   public enum GroupCallState {

app/src/main/java/org/thoughtcrime/securesms/service/WebRtcCallService.java

@@ -6,6 +6,8 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.media.AudioManager;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
 import android.os.Build;
 import android.os.IBinder;
 import android.os.ResultReceiver;
@@ -41,6 +43,7 @@ import org.thoughtcrime.securesms.events.GroupCallPeekEvent;
 import org.thoughtcrime.securesms.events.WebRtcViewModel;
 import org.thoughtcrime.securesms.groups.GroupId;
 import org.thoughtcrime.securesms.groups.GroupManager;
+import org.thoughtcrime.securesms.jobmanager.impl.NetworkConstraint;
 import org.thoughtcrime.securesms.jobs.GroupCallUpdateSendJob;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientId;
@@ -148,6 +151,7 @@ public class WebRtcCallService extends Service implements CallManager.Observer,
   public static final String ACTION_SET_MUTE_AUDIO                      = "SET_MUTE_AUDIO";
   public static final String ACTION_FLIP_CAMERA                         = "FLIP_CAMERA";
   public static final String ACTION_BLUETOOTH_CHANGE                    = "BLUETOOTH_CHANGE";
+  public static final String ACTION_NETWORK_CHANGE                      = "NETWORK_CHANGE";
   public static final String ACTION_WIRED_HEADSET_CHANGE                = "WIRED_HEADSET_CHANGE";
   public static final String ACTION_SCREEN_OFF                          = "SCREEN_OFF";
   public static final String ACTION_IS_IN_CALL_QUERY                    = "IS_IN_CALL";
@@ -212,6 +216,7 @@ public class WebRtcCallService extends Service implements CallManager.Observer,
   private SignalServiceAccountManager     accountManager;
   private BluetoothStateManager           bluetoothStateManager;
   private WiredHeadsetStateReceiver       wiredHeadsetStateReceiver;
+  private NetworkReceiver                 networkReceiver;
   private PowerButtonReceiver             powerButtonReceiver;
   private LockManager                     lockManager;
   private UncaughtExceptionHandlerManager uncaughtExceptionHandlerManager;
@@ -241,6 +246,7 @@ public class WebRtcCallService extends Service implements CallManager.Observer,
 
     registerUncaughtExceptionHandler();
     registerWiredHeadsetStateReceiver();
+    registerNetworkReceiver();
 
     TelephonyUtil.getManager(this)
                  .listen(hangUpRtcOnDeviceCallAnswered, PhoneStateListener.LISTEN_CALL_STATE);
@@ -328,6 +334,8 @@ public class WebRtcCallService extends Service implements CallManager.Observer,
       powerButtonReceiver = null;
     }
 
+    unregisterNetworkReceiver();
+
     TelephonyUtil.getManager(this)
                  .listen(hangUpRtcOnDeviceCallAnswered, PhoneStateListener.LISTEN_NONE);
   }
@@ -371,6 +379,22 @@ public class WebRtcCallService extends Service implements CallManager.Observer,
     registerReceiver(wiredHeadsetStateReceiver, new IntentFilter(action));
   }
 
+  private void registerNetworkReceiver() {
+    if (networkReceiver == null) {
+      networkReceiver = new NetworkReceiver();
+
+      registerReceiver(networkReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
+    }
+  }
+
+  private void unregisterNetworkReceiver() {
+    if (networkReceiver != null) {
+      unregisterReceiver(networkReceiver);
+
+      networkReceiver = null;
+    }
+  }
+
   public void registerPowerButtonReceiver() {
     if (powerButtonReceiver == null) {
       powerButtonReceiver = new PowerButtonReceiver();
@@ -502,6 +526,19 @@ public class WebRtcCallService extends Service implements CallManager.Observer,
     }
   }
 
+  private static class NetworkReceiver extends BroadcastReceiver {
+    @Override
+    public void onReceive(Context context, Intent intent) {
+      ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
+      NetworkInfo         activeNetworkInfo   = connectivityManager.getActiveNetworkInfo();
+      Intent              serviceIntent       = new Intent(context, WebRtcCallService.class);
+
+      serviceIntent.setAction(ACTION_NETWORK_CHANGE);
+      serviceIntent.putExtra(EXTRA_AVAILABLE, activeNetworkInfo != null && activeNetworkInfo.isConnected());
+      context.startService(serviceIntent);
+    }
+  }
+
   private static class PowerButtonReceiver extends BroadcastReceiver {
     @Override
     public void onReceive(@NonNull Context context, @NonNull Intent intent) {
@@ -1057,8 +1094,11 @@ public class WebRtcCallService extends Service implements CallManager.Observer,
               .putExtra(EXTRA_GROUP_CALL_HASH, groupCall.hashCode());
 
         startService(intent);
-      } catch (IOException | VerificationFailedException e) {
+      } catch (IOException e) {
-        Log.w(TAG, "Unable to fetch group membership proof", e);
+        Log.w(TAG, "Unable to get group membership proof from service", e);
+        onEnded(groupCall, GroupCall.GroupCallEndReason.SFU_CLIENT_FAILED_TO_JOIN);
+      } catch (VerificationFailedException e) {
+        Log.w(TAG, "Unable to verify group membership proof", e);
         onEnded(groupCall, GroupCall.GroupCallEndReason.DEVICE_EXPLICITLY_DISCONNECTED);
       }
     });

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/GroupActionProcessor.java

@@ -18,6 +18,7 @@ import org.thoughtcrime.securesms.groups.GroupManager;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.thoughtcrime.securesms.ringrtc.RemotePeer;
+import org.thoughtcrime.securesms.service.webrtc.state.VideoState;
 import org.thoughtcrime.securesms.service.webrtc.state.WebRtcServiceState;
 import org.thoughtcrime.securesms.service.webrtc.state.WebRtcServiceStateBuilder;
 import org.thoughtcrime.securesms.webrtc.locks.LockManager;
@@ -271,6 +272,28 @@ public class GroupActionProcessor extends DeviceAwareActionProcessor {
       return groupCallFailure(currentState, "Unable to disconnect from group call", e);
     }
 
+    if (groupCallEndReason != GroupCall.GroupCallEndReason.DEVICE_EXPLICITLY_DISCONNECTED) {
+      Log.i(tag, "Group call ended unexpectedly, reinitializing and dropping back to lobby");
+      Recipient  currentRecipient = currentState.getCallInfoState().getCallRecipient();
+      VideoState videoState       = currentState.getVideoState();
+
+      currentState = terminateGroupCall(currentState, false).builder()
+                                                            .actionProcessor(new GroupNetworkUnavailableActionProcessor(webRtcInteractor))
+                                                            .changeVideoState()
+                                                            .eglBase(videoState.getEglBase())
+                                                            .camera(videoState.getCamera())
+                                                            .localSink(videoState.getLocalSink())
+                                                            .commit()
+                                                            .changeCallInfoState()
+                                                            .callState(WebRtcViewModel.State.CALL_PRE_JOIN)
+                                                            .callRecipient(currentRecipient)
+                                                            .build();
+
+      currentState = WebRtcVideoUtil.initializeVanityCamera(WebRtcVideoUtil.reinitializeCamera(context, webRtcInteractor.getCameraEventListener(), currentState));
+
+      return currentState.getActionProcessor().handlePreJoinCall(currentState, new RemotePeer(currentRecipient.getId()));
+    }
+
     currentState = currentState.builder()
                                .changeCallInfoState()
                                .callState(WebRtcViewModel.State.CALL_DISCONNECTED)
@@ -313,6 +336,10 @@ public class GroupActionProcessor extends DeviceAwareActionProcessor {
   }
 
   public synchronized @NonNull WebRtcServiceState terminateGroupCall(@NonNull WebRtcServiceState currentState) {
+    return terminateGroupCall(currentState, true);
+  }
+
+  public synchronized @NonNull WebRtcServiceState terminateGroupCall(@NonNull WebRtcServiceState currentState, boolean terminateVideo) {
     webRtcInteractor.updatePhoneState(LockManager.PhoneState.PROCESSING);
     webRtcInteractor.stopForegroundService();
     boolean playDisconnectSound = currentState.getCallInfoState().getCallState() == WebRtcViewModel.State.CALL_DISCONNECTED;
@@ -321,7 +348,9 @@ public class GroupActionProcessor extends DeviceAwareActionProcessor {
 
     webRtcInteractor.updatePhoneState(LockManager.PhoneState.IDLE);
 
-    WebRtcVideoUtil.deinitializeVideo(currentState);
+    if (terminateVideo) {
+      WebRtcVideoUtil.deinitializeVideo(currentState);
+    }
 
     GroupCallSafetyNumberChangeNotificationUtil.cancelNotification(context, currentState.getCallInfoState().getCallRecipient());
 

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/GroupNetworkUnavailableActionProcessor.java

@@ -0,0 +1,80 @@
+package org.thoughtcrime.securesms.service.webrtc;
+
+import android.content.Context;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
+
+import androidx.annotation.NonNull;
+
+import org.signal.core.util.logging.Log;
+import org.signal.ringrtc.GroupCall;
+import org.thoughtcrime.securesms.BuildConfig;
+import org.thoughtcrime.securesms.events.WebRtcViewModel;
+import org.thoughtcrime.securesms.keyvalue.SignalStore;
+import org.thoughtcrime.securesms.ringrtc.RemotePeer;
+import org.thoughtcrime.securesms.service.webrtc.state.WebRtcServiceState;
+
+/**
+ * Processor which is utilized when the network becomes unavailable during a group call. In general,
+ * this is triggered whenever there is a call ended, and the ending was not the result of direct user
+ * action.
+ *
+ * This class will check the network status when handlePreJoinCall is invoked, and transition to
+ * GroupPreJoinActionProcessor as network becomes available again.
+ */
+class GroupNetworkUnavailableActionProcessor extends WebRtcActionProcessor {
+
+  private static final String TAG = Log.tag(GroupNetworkUnavailableActionProcessor.class);
+
+  public GroupNetworkUnavailableActionProcessor(@NonNull WebRtcInteractor webRtcInteractor) {
+    super(webRtcInteractor, TAG);
+  }
+
+  @Override
+  protected @NonNull WebRtcServiceState handlePreJoinCall(@NonNull WebRtcServiceState currentState, @NonNull RemotePeer remotePeer) {
+    Log.i(TAG, "handlePreJoinCall():");
+
+    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
+    NetworkInfo         activeNetworkInfo   = connectivityManager.getActiveNetworkInfo();
+
+    if (activeNetworkInfo != null && activeNetworkInfo.isConnected()) {
+      GroupPreJoinActionProcessor processor = new GroupPreJoinActionProcessor(webRtcInteractor);
+      return processor.handlePreJoinCall(currentState.builder().actionProcessor(processor).build(), remotePeer);
+    }
+
+    byte[]    groupId   = currentState.getCallInfoState().getCallRecipient().requireGroupId().getDecodedId();
+    GroupCall groupCall = webRtcInteractor.getCallManager().createGroupCall(groupId,
+                                                                            BuildConfig.SIGNAL_SFU_URL,
+                                                                            currentState.getVideoState().requireEglBase(),
+                                                                            webRtcInteractor.getGroupCallObserver());
+
+    return currentState.builder()
+                       .changeCallInfoState()
+                       .callState(WebRtcViewModel.State.NETWORK_FAILURE)
+                       .groupCall(groupCall)
+                       .groupCallState(WebRtcViewModel.GroupCallState.DISCONNECTED)
+                       .build();
+  }
+
+  @Override
+  protected @NonNull WebRtcServiceState handleCancelPreJoinCall(@NonNull WebRtcServiceState currentState) {
+    Log.i(TAG, "handleCancelPreJoinCall():");
+
+    WebRtcVideoUtil.deinitializeVideo(currentState);
+
+    return new WebRtcServiceState(new IdleActionProcessor(webRtcInteractor));
+  }
+
+  @Override
+  public @NonNull WebRtcServiceState handleNetworkChanged(@NonNull WebRtcServiceState currentState, boolean available) {
+    if (available) {
+      return currentState.builder()
+                         .actionProcessor(new GroupPreJoinActionProcessor(webRtcInteractor))
+                         .changeCallInfoState()
+                         .callState(WebRtcViewModel.State.CALL_PRE_JOIN)
+                         .build();
+    } else {
+      return currentState;
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/GroupPreJoinActionProcessor.java

@@ -187,4 +187,17 @@ public class GroupPreJoinActionProcessor extends GroupActionProcessor {
                        .isMicrophoneEnabled(!muted)
                        .build();
   }
+
+  @Override
+  public @NonNull WebRtcServiceState handleNetworkChanged(@NonNull WebRtcServiceState currentState, boolean available) {
+    if (!available) {
+      return currentState.builder()
+                         .actionProcessor(new GroupNetworkUnavailableActionProcessor(webRtcInteractor))
+                         .changeCallInfoState()
+                         .callState(WebRtcViewModel.State.NETWORK_FAILURE)
+                         .build();
+    } else {
+      return currentState;
+    }
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/IdleActionProcessor.java

@@ -54,7 +54,7 @@ public class IdleActionProcessor extends WebRtcActionProcessor {
     WebRtcActionProcessor processor   = isGroupCall ? new GroupPreJoinActionProcessor(webRtcInteractor)
                                                     : new PreJoinActionProcessor(webRtcInteractor);
 
-    currentState = initializeVanityCamera(WebRtcVideoUtil.initializeVideo(context, webRtcInteractor.getCameraEventListener(), currentState));
+    currentState = WebRtcVideoUtil.initializeVanityCamera(WebRtcVideoUtil.initializeVideo(context, webRtcInteractor.getCameraEventListener(), currentState));
 
     currentState = currentState.builder()
                                .actionProcessor(processor)
@@ -66,30 +66,4 @@ public class IdleActionProcessor extends WebRtcActionProcessor {
     return isGroupCall ? currentState.getActionProcessor().handlePreJoinCall(currentState, remotePeer)
                        : currentState;
   }
-
-  private @NonNull WebRtcServiceState initializeVanityCamera(@NonNull WebRtcServiceState currentState) {
-    Camera             camera = currentState.getVideoState().requireCamera();
-    BroadcastVideoSink sink   = currentState.getVideoState().requireLocalSink();
-
-    if (camera.hasCapturer()) {
-      camera.initCapturer(new CapturerObserver() {
-        @Override
-        public void onFrameCaptured(VideoFrame videoFrame) {
-          sink.onFrame(videoFrame);
-        }
-
-        @Override
-        public void onCapturerStarted(boolean success) {}
-
-        @Override
-        public void onCapturerStopped() {}
-      });
-      camera.setEnabled(true);
-    }
-
-    return currentState.builder()
-                       .changeLocalDeviceState()
-                       .cameraState(camera.getCameraState())
-                       .build();
-  }
 }

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/WebRtcActionProcessor.java

@@ -77,6 +77,7 @@ import static org.thoughtcrime.securesms.service.WebRtcCallService.ACTION_LOCAL_
 import static org.thoughtcrime.securesms.service.WebRtcCallService.ACTION_LOCAL_RINGING;
 import static org.thoughtcrime.securesms.service.WebRtcCallService.ACTION_MESSAGE_SENT_ERROR;
 import static org.thoughtcrime.securesms.service.WebRtcCallService.ACTION_MESSAGE_SENT_SUCCESS;
+import static org.thoughtcrime.securesms.service.WebRtcCallService.ACTION_NETWORK_CHANGE;
 import static org.thoughtcrime.securesms.service.WebRtcCallService.ACTION_OUTGOING_CALL;
 import static org.thoughtcrime.securesms.service.WebRtcCallService.ACTION_PRE_JOIN_CALL;
 import static org.thoughtcrime.securesms.service.WebRtcCallService.ACTION_RECEIVED_OFFER_EXPIRED;
@@ -213,6 +214,7 @@ public abstract class WebRtcActionProcessor {
       case ACTION_SET_AUDIO_BLUETOOTH:                 return handleSetBluetoothAudio(currentState, intent.getBooleanExtra(EXTRA_BLUETOOTH, false));
       case ACTION_BLUETOOTH_CHANGE:                    return handleBluetoothChange(currentState, getAvailable(intent));
       case ACTION_CAMERA_SWITCH_COMPLETED:             return handleCameraSwitchCompleted(currentState, getCameraState(intent));
+      case ACTION_NETWORK_CHANGE:                      return handleNetworkChanged(currentState, getAvailable(intent));
 
       // End Call Actions
       case ACTION_ENDED_REMOTE_HANGUP:
@@ -598,6 +600,11 @@ public abstract class WebRtcActionProcessor {
     return currentState;
   }
 
+  public @NonNull WebRtcServiceState handleNetworkChanged(@NonNull WebRtcServiceState currentState, boolean available) {
+    Log.i(tag, "handleNetworkChanged not processed");
+    return currentState;
+  }
+
   //endregion Local device
 
   //region End call

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/WebRtcVideoUtil.java

@@ -11,7 +11,9 @@ import org.thoughtcrime.securesms.ringrtc.CameraState;
 import org.thoughtcrime.securesms.service.webrtc.state.WebRtcServiceState;
 import org.thoughtcrime.securesms.service.webrtc.state.WebRtcServiceStateBuilder;
 import org.thoughtcrime.securesms.util.Util;
+import org.webrtc.CapturerObserver;
 import org.webrtc.EglBase;
+import org.webrtc.VideoFrame;
 
 /**
  * Helper for initializing, reinitializing, and deinitializing the camera and it's related
@@ -93,4 +95,30 @@ public final class WebRtcVideoUtil {
                        .cameraState(CameraState.UNKNOWN)
                        .build();
   }
+
+  public static @NonNull WebRtcServiceState initializeVanityCamera(@NonNull WebRtcServiceState currentState) {
+    Camera             camera = currentState.getVideoState().requireCamera();
+    BroadcastVideoSink sink   = currentState.getVideoState().requireLocalSink();
+
+    if (camera.hasCapturer()) {
+      camera.initCapturer(new CapturerObserver() {
+        @Override
+        public void onFrameCaptured(VideoFrame videoFrame) {
+          sink.onFrame(videoFrame);
+        }
+
+        @Override
+        public void onCapturerStarted(boolean success) {}
+
+        @Override
+        public void onCapturerStopped() {}
+      });
+      camera.setEnabled(true);
+    }
+
+    return currentState.builder()
+                       .changeLocalDeviceState()
+                       .cameraState(camera.getCameraState())
+                       .build();
+  }
 }

app/src/main/res/layout/webrtc_call_view.xml

@@ -322,6 +322,25 @@
 
         </LinearLayout>
 
+        <com.google.android.material.button.MaterialButton
+            android:id="@+id/call_screen_error_cancel"
+            style="@style/Widget.Signal.Button.Flat"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="16dp"
+            android:layout_marginEnd="16dp"
+            android:layout_marginBottom="32dp"
+            android:layout_weight="1"
+            android:text="@android:string/cancel"
+            android:textAllCaps="false"
+            android:textColor="@color/core_white"
+            android:visibility="gone"
+            app:backgroundTint="@color/transparent_white_40"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            tools:visibility="visible" />
+
         <ViewStub
             android:id="@+id/call_screen_group_call_speaker_hint"
             android:layout="@layout/group_call_speaker_hint"