Use helper function of registerReceiver() that doesn't export receiver

bramble-android/build.gradle

@@ -3,8 +3,8 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 android {
-	compileSdkVersion 33
+	compileSdkVersion 34
-	buildToolsVersion '33.0.0'
+	buildToolsVersion '34.0.0'
 
 	packagingOptions {
 		doNotStrip '**/*.so'

bramble-android/src/main/java/org/briarproject/bramble/battery/AndroidBatteryManager.java

@@ -30,6 +30,7 @@ import static android.os.PowerManager.ACTION_LOW_POWER_STANDBY_ENABLED_CHANGED;
 import static android.os.PowerManager.ACTION_POWER_SAVE_MODE_CHANGED;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.AndroidUtils.registerReceiver;
 
 class AndroidBatteryManager implements BatteryManager, Service {
 
@@ -52,7 +53,7 @@ class AndroidBatteryManager implements BatteryManager, Service {
 	public boolean isCharging() {
 		// Get the sticky intent for ACTION_BATTERY_CHANGED
 		IntentFilter filter = new IntentFilter(ACTION_BATTERY_CHANGED);
-		Intent i = appContext.registerReceiver(null, filter);
+		Intent i = registerReceiver(appContext, null, filter);
 		if (i == null) return false;
 		int status = i.getIntExtra(EXTRA_PLUGGED, 0);
 		return status != 0;
@@ -71,7 +72,7 @@ class AndroidBatteryManager implements BatteryManager, Service {
 			filter.addAction(ACTION_LOW_POWER_STANDBY_ENABLED_CHANGED);
 			filter.addAction(ACTION_DEVICE_LIGHT_IDLE_MODE_CHANGED);
 		}
-		appContext.registerReceiver(batteryReceiver, filter);
+		registerReceiver(appContext, batteryReceiver, filter);
 	}
 
 	@Override

bramble-android/src/main/java/org/briarproject/bramble/network/AndroidNetworkManager.java

@@ -55,6 +55,7 @@ import static java.util.concurrent.TimeUnit.SECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.AndroidUtils.registerReceiver;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.nullsafety.NullSafety.requireNonNull;
 
@@ -103,7 +104,7 @@ class AndroidNetworkManager implements NetworkManager, Service {
 		filter.addAction(WIFI_AP_STATE_CHANGED_ACTION);
 		filter.addAction(WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
 		if (SDK_INT >= 23) filter.addAction(ACTION_DEVICE_IDLE_MODE_CHANGED);
-		app.registerReceiver(networkStateReceiver, filter);
+		registerReceiver(app, networkStateReceiver, filter);
 	}
 
 	@Override

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPlugin.java

@@ -56,6 +56,7 @@ import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.AndroidUtils.hasBtConnectPermission;
+import static org.briarproject.bramble.util.AndroidUtils.registerReceiver;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 
 @MethodsNotNullByDefault
@@ -112,7 +113,7 @@ class AndroidBluetoothPlugin extends
 		filter.addAction(ACTION_STATE_CHANGED);
 		filter.addAction(ACTION_SCAN_MODE_CHANGED);
 		receiver = new BluetoothStateReceiver();
-		app.registerReceiver(receiver, filter);
+		registerReceiver(app, receiver, filter);
 	}
 
 	@Override
@@ -237,7 +238,7 @@ class AndroidBluetoothPlugin extends
 		filter.addAction(ACTION_DISCOVERY_STARTED);
 		filter.addAction(ACTION_DISCOVERY_FINISHED);
 		filter.addAction(ACTION_FOUND);
-		app.registerReceiver(receiver, filter);
+		AndroidUtils.registerReceiver(app, receiver, filter);
 		try {
 			if (adapter.startDiscovery()) {
 				long now = clock.currentTimeMillis();

bramble-android/src/main/java/org/briarproject/bramble/util/AndroidUtils.java

@@ -2,7 +2,10 @@ package org.briarproject.bramble.util;
 
 import android.annotation.SuppressLint;
 import android.bluetooth.BluetoothAdapter;
+import android.content.BroadcastReceiver;
 import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
 import android.os.Build;
 import android.os.Looper;
 import android.provider.Settings;
@@ -21,6 +24,7 @@ import javax.annotation.Nullable;
 import static android.Manifest.permission.BLUETOOTH_CONNECT;
 import static android.app.PendingIntent.FLAG_IMMUTABLE;
 import static android.content.Context.MODE_PRIVATE;
+import static android.content.Context.RECEIVER_NOT_EXPORTED;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.os.Process.myPid;
@@ -141,4 +145,20 @@ public class AndroidUtils {
 		}
 		return flags;
 	}
+
+	/**
+	 * Could be replaced to a similar call in ContextCompat once we
+	 * use and upgrade to version 1.9.0 or higher of the AndroidX Core library.
+	 */
+	@Nullable
+	@SuppressLint("UnspecifiedRegisterReceiverFlag") // we specify where needed
+	public static Intent registerReceiver(Context ctx,
+			@Nullable BroadcastReceiver receiver, IntentFilter filter) {
+		if (SDK_INT >= 33) {
+			return ctx.registerReceiver(receiver, filter,
+					RECEIVER_NOT_EXPORTED);
+		} else {
+			return ctx.registerReceiver(receiver, filter);
+		}
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/AbstractBluetoothPlugin.java

@@ -388,7 +388,6 @@ abstract class AbstractBluetoothPlugin<S, SS> implements BluetoothPlugin,
 		}
 		// Validate the UUID
 		try {
-			//noinspection ResultOfMethodCallIgnored
 			UUID.fromString(uuid);
 		} catch (IllegalArgumentException e) {
 			if (LOG.isLoggable(WARNING)) LOG.warning("Invalid UUID " + uuid);

briar-android/build.gradle

@@ -16,8 +16,8 @@ def getStdout = { command, defaultValue ->
 }
 
 android {
-	compileSdk 33
+	compileSdk 34
-	buildToolsVersion '33.0.0'
+	buildToolsVersion '34.0.0'
 
 	packagingOptions {
 		doNotStrip '**/*.so'

briar-android/src/main/java/org/briarproject/briar/android/BriarService.java

@@ -22,6 +22,7 @@ import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.util.AndroidUtils;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.logout.HideUiActivity;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
@@ -174,7 +175,8 @@ public class BriarService extends Service {
 			filter.addAction(ACTION_SHUTDOWN);
 			filter.addAction("android.intent.action.QUICKBOOT_POWEROFF");
 			filter.addAction("com.htc.intent.action.QUICKBOOT_POWEROFF");
-			registerReceiver(receiver, filter);
+			AndroidUtils.registerReceiver(getApplicationContext(), receiver,
+					filter);
 		}, "LifecycleStartup");
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/DozeWatchdogImpl.java

@@ -21,6 +21,7 @@ import static android.os.PowerManager.ACTION_DEVICE_LIGHT_IDLE_MODE_CHANGED;
 import static android.os.PowerManager.ACTION_LOW_POWER_STANDBY_ENABLED_CHANGED;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.AndroidUtils.registerReceiver;
 
 class DozeWatchdogImpl implements DozeWatchdog, Service {
 
@@ -48,7 +49,7 @@ class DozeWatchdogImpl implements DozeWatchdog, Service {
 			filter.addAction(ACTION_DEVICE_LIGHT_IDLE_MODE_CHANGED);
 			filter.addAction(ACTION_LOW_POWER_STANDBY_ENABLED_CHANGED);
 		}
-		appContext.registerReceiver(receiver, filter);
+		registerReceiver(appContext, receiver, filter);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/ScreenFilterMonitorImpl.java

@@ -49,6 +49,7 @@ import static android.content.pm.PackageManager.GET_PERMISSIONS;
 import static android.content.pm.PackageManager.GET_SIGNATURES;
 import static android.os.Build.VERSION.SDK_INT;
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.AndroidUtils.registerReceiver;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
@@ -207,7 +208,7 @@ class ScreenFilterMonitorImpl implements ScreenFilterMonitor, Service {
 			filter.addAction(ACTION_PACKAGE_REPLACED);
 			filter.addDataScheme("package");
 			receiver = new PackageBroadcastReceiver();
-			app.registerReceiver(receiver, filter);
+			registerReceiver(app, receiver, filter);
 			cachedApps = null;
 		});
 	}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactViewModel.java

@@ -88,6 +88,7 @@ import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
 import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
+import static org.briarproject.bramble.util.AndroidUtils.registerReceiver;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.ISO_8859_1;
 import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactPermissionManager.areEssentialPermissionsGranted;
@@ -208,7 +209,7 @@ class AddNearbyContactViewModel extends AndroidViewModel
 		qrCodeDecoder = new QrCodeDecoder(androidExecutor, ioExecutor, this);
 		eventBus.addListener(this);
 		IntentFilter filter = new IntentFilter(ACTION_SCAN_MODE_CHANGED);
-		getApplication().registerReceiver(bluetoothReceiver, filter);
+		registerReceiver(getApplication(), bluetoothReceiver, filter);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/PluginViewModel.java

@@ -48,6 +48,7 @@ import static java.util.logging.Level.INFO;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.plugin.Plugin.PREF_PLUGIN_ENABLE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
+import static org.briarproject.bramble.util.AndroidUtils.registerReceiver;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.now;
 
@@ -96,7 +97,7 @@ public class PluginViewModel extends DbViewModel implements EventListener {
 		this.eventBus = eventBus;
 		eventBus.addListener(this);
 		receiver = new BluetoothStateReceiver();
-		app.registerReceiver(receiver, new IntentFilter(ACTION_STATE_CHANGED));
+		registerReceiver(app, receiver, new IntentFilter(ACTION_STATE_CHANGED));
 		networkStatus.setValue(networkManager.getNetworkStatus());
 		torPluginState.setValue(getTransportState(TorConstants.ID));
 		wifiPluginState.setValue(getTransportState(LanTcpConstants.ID));

briar-android/src/main/java/org/briarproject/briar/android/util/UiUtils.java

@@ -1,12 +1,15 @@
 package org.briarproject.briar.android.util;
 
+import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.app.ActivityManager;
 import android.app.ActivityManager.MemoryInfo;
 import android.app.KeyguardManager;
 import android.content.ActivityNotFoundException;
+import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
+import android.content.IntentFilter;
 import android.content.res.Configuration;
 import android.content.res.Resources;
 import android.graphics.drawable.Drawable;
@@ -67,6 +70,7 @@ import androidx.lifecycle.Observer;
 import androidx.vectordrawable.graphics.drawable.VectorDrawableCompat;
 
 import static android.content.Context.KEYGUARD_SERVICE;
+import static android.content.Context.RECEIVER_NOT_EXPORTED;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
 import static android.os.Build.MANUFACTURER;
 import static android.os.Build.VERSION.SDK_INT;
@@ -399,7 +403,7 @@ public class UiUtils {
 	public static void startDevReportActivity(Context ctx,
 			Class<? extends FragmentActivity> activity, @Nullable Throwable t,
 			@Nullable Long appStartTime, @Nullable byte[] logKey, @Nullable
-			String initialComment) {
+	String initialComment) {
 		// Collect memory stats from the current process, not the crash
 		// reporter process
 		ActivityManager am =