frontend/android: refactor network related code

Beerosagos · Beerosagos · commit dfb581308d4d · 2025-11-12T09:48:35.000+01:00
Our MainActivity code is quite complicated and mixes a lot of different
things. This change moves the code related to network management (e.g. to
    display alerts when the network is not available) to a dedicated
helper class and declutters the main activity a bit.

It also fixes a bug that caused the app to misdetect mobile connection
or missing connectivity when switching between WIFI and cellular
connection.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## Unreleased
 - Add feedback link to guide and about settings
+- Android: fix connectivity misdetection when switching between WIFI and cellular network.
 
 ## v4.49.0
 - Bundle BitBox02 Nova firmware version v9.24.0
diff --git a/frontends/android/BitBoxApp/app/src/main/java/ch/shiftcrypto/bitboxapp/GoViewModel.java b/frontends/android/BitBoxApp/app/src/main/java/ch/shiftcrypto/bitboxapp/GoViewModel.java
@@ -8,8 +8,6 @@
 import android.hardware.usb.UsbEndpoint;
 import android.hardware.usb.UsbInterface;
 import android.hardware.usb.UsbManager;
-import android.net.ConnectivityManager;
-import android.net.NetworkCapabilities;
 import android.os.Handler;
 
 import androidx.lifecycle.AndroidViewModel;
@@ -170,14 +168,7 @@ public void bluetoothConnect(String identifier) {
 
         @Override
         public boolean usingMobileData() {
-            // Adapted from https://stackoverflow.com/a/53243938
-            ConnectivityManager cm = (ConnectivityManager) getApplication().getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
-            if (cm == null) {
-                return false;
-            }
-            NetworkCapabilities capabilities = cm.getNetworkCapabilities(cm.getActiveNetwork());
-            return capabilities != null && capabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR);
-
+            return networkHelper.usingMobileData();
         }
 
         @Override
@@ -207,6 +198,15 @@ public boolean detectDarkTheme() {
     private final MutableLiveData<Boolean> authSetting = new MutableLiveData<>(false);
     private final GoEnvironment goEnvironment;
     private final GoAPI goAPI;
+    private NetworkHelper networkHelper;
+
+    public NetworkHelper getNetworkHelper() {
+        return networkHelper;
+    }
+
+    public void setNetworkHelper(NetworkHelper networkHelper) {
+        this.networkHelper = networkHelper;
+    }
 
     public GoViewModel(Application app) {
         super(app);
diff --git a/frontends/android/BitBoxApp/app/src/main/java/ch/shiftcrypto/bitboxapp/MainActivity.java b/frontends/android/BitBoxApp/app/src/main/java/ch/shiftcrypto/bitboxapp/MainActivity.java
@@ -15,9 +15,6 @@
 import android.hardware.usb.UsbDevice;
 import android.hardware.usb.UsbManager;
 import android.net.ConnectivityManager;
-import android.net.Network;
-import android.net.NetworkCapabilities;
-import android.net.NetworkRequest;
 import android.net.Uri;
 import android.os.Bundle;
 import android.os.Handler;
@@ -62,47 +59,6 @@ public class MainActivity extends AppCompatActivity {
 
     private BitBoxWebChromeClient webChrome;
 
-    private ConnectivityManager connectivityManager;
-    private ConnectivityManager.NetworkCallback networkCallback;
-
-    private boolean hasInternetConnectivity(NetworkCapabilities capabilities) {
-        // To avoid false positives, if we can't obtain connectivity info,
-        // we return true.
-        // Note: this should never happen per Android documentation, as:
-        // - these can not be null it come from the onCapabilitiesChanged callback.
-        // - when obtained with getNetworkCapabilities(network), they can only be null if the
-        //   network is null or unknown, but we guard against both in the caller.
-        if (capabilities == null) {
-            Util.log("Got null capabilities when we shouldn't have. Assuming we are online.");
-            return true;
-        }
-
-
-        boolean hasInternet = capabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET);
-
-        // We need to check for both internet and validated, since validated reports that the system
-        // found connectivity the last time it checked. But if this callback triggers when going offline
-        // (e.g. airplane mode), this bit would still be true when we execute this method.
-        boolean isValidated = capabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED);
-        return hasInternet && isValidated;
-
-        // Fallback for older devices
-    }
-
-    private void checkConnectivity() {
-        Network activeNetwork = connectivityManager.getActiveNetwork();
-
-        // If there is no active network (e.g. airplane mode), there is no check to perform.
-        if (activeNetwork == null) {
-            Mobileserver.setOnline(false);
-            return;
-        }
-
-        NetworkCapabilities capabilities = connectivityManager.getNetworkCapabilities(activeNetwork);
-
-        Mobileserver.setOnline(hasInternetConnectivity(capabilities));
-    }
-
     // Connection to bind with GoService
     private final ServiceConnection connection = new ServiceConnection() {
 
@@ -129,14 +85,6 @@ public void onReceive(Context context, Intent intent) {
         }
     };
 
-    private final BroadcastReceiver networkStateReceiver = new BroadcastReceiver() {
-        @Override
-        public void onReceive(Context context, Intent intent) {
-            Mobileserver.usingMobileDataChanged();
-        }
-    };
-
-
     @Override
     public void onConfigurationChanged(Configuration newConfig) {
         int currentNightMode = newConfig.uiMode & Configuration.UI_MODE_NIGHT_MASK;
@@ -248,20 +196,7 @@ protected void onCreate(Bundle savedInstanceState) {
         // In that case, handleIntent() is not called with ACTION_USB_DEVICE_ATTACHED.
         this.updateDevice();
 
-        connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
-        networkCallback = new ConnectivityManager.NetworkCallback() {
-            @Override
-            public void onCapabilitiesChanged(@NonNull android.net.Network network, @NonNull android.net.NetworkCapabilities capabilities) {
-                super.onCapabilitiesChanged(network, capabilities);
-                Mobileserver.setOnline(hasInternetConnectivity(capabilities));
-            }
-            // When we lose the network, onCapabilitiesChanged does not trigger, so we need to override onLost.
-            @Override
-            public void onLost(@NonNull Network network) {
-                super.onLost(network);
-                Mobileserver.setOnline(false);
-            }
-        };
+        goViewModel.setNetworkHelper(new NetworkHelper((ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE)));
 
         getOnBackPressedDispatcher().addCallback(this, new OnBackPressedCallback(true) {
             @Override
@@ -337,7 +272,7 @@ private void startServer() {
         goService.startServer(getApplicationContext().getFilesDir().getAbsolutePath(), gVM.getGoEnvironment(), gVM.getGoAPI());
 
         // Trigger connectivity check (as the network may already be unavailable when the app starts).
-        checkConnectivity();
+        gVM.getNetworkHelper().checkConnectivity();
     }
 
     @Override
@@ -355,15 +290,7 @@ protected void onStart() {
         Util.log("lifecycle: onStart");
         final GoViewModel goViewModel = ViewModelProviders.of(this).get(GoViewModel.class);
         goViewModel.getIsDarkTheme().observe(this, this::setDarkTheme);
-
-
-        NetworkRequest request = new NetworkRequest.Builder()
-            .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
-            .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
-            .addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
-            .build();
-        // Register the network callback to listen for changes in network capabilities.
-        connectivityManager.registerNetworkCallback(request, networkCallback);
+        goViewModel.getNetworkHelper().registerNetworkCallback();
     }
 
     @Override
@@ -389,11 +316,9 @@ protected void onResume() {
                 ContextCompat.RECEIVER_NOT_EXPORTED
         );
 
-        // Listen on changes in the network connection. We are interested in if the user is connected to a mobile data connection.
-        registerReceiver(this.networkStateReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
-
         // Trigger connectivity check (as the network may already be unavailable when the app starts).
-        checkConnectivity();
+        final GoViewModel goViewModel = ViewModelProviders.of(this).get(GoViewModel.class);
+        goViewModel.getNetworkHelper().checkConnectivity();
 
         Intent intent = getIntent();
         handleIntent(intent);
@@ -404,7 +329,6 @@ protected void onPause() {
         super.onPause();
         Util.log("lifecycle: onPause");
         unregisterReceiver(this.usbStateReceiver);
-        unregisterReceiver(this.networkStateReceiver);
     }
 
     private void handleIntent(Intent intent) {
@@ -472,9 +396,8 @@ private void updateDevice() {
     @Override
     protected void onStop() {
         super.onStop();
-        if (connectivityManager != null && networkCallback != null) {
-            connectivityManager.unregisterNetworkCallback(networkCallback);
-        }
+        final GoViewModel goViewModel = ViewModelProviders.of(this).get(GoViewModel.class);
+        goViewModel.getNetworkHelper().unregisterNetworkCallback();
         Util.log("lifecycle: onStop");
     }
 
diff --git a/frontends/android/BitBoxApp/app/src/main/java/ch/shiftcrypto/bitboxapp/NetworkHelper.java b/frontends/android/BitBoxApp/app/src/main/java/ch/shiftcrypto/bitboxapp/NetworkHelper.java
@@ -0,0 +1,95 @@
+package ch.shiftcrypto.bitboxapp;
+
+import android.net.ConnectivityManager;
+import android.net.Network;
+import android.net.NetworkCapabilities;
+
+import androidx.annotation.NonNull;
+
+import mobileserver.Mobileserver;
+
+public class NetworkHelper {
+    private final ConnectivityManager connectivityManager;
+    private final ConnectivityManager.NetworkCallback networkCallback;
+
+    public NetworkHelper(ConnectivityManager connectivityManager) {
+        this.connectivityManager = connectivityManager;
+        networkCallback = new ConnectivityManager.NetworkCallback() {
+            @Override
+            public void onCapabilitiesChanged(@NonNull android.net.Network network, @NonNull android.net.NetworkCapabilities capabilities) {
+                super.onCapabilitiesChanged(network, capabilities);
+                checkConnectivity();
+                Mobileserver.usingMobileDataChanged();
+            }
+
+            @Override
+            public void onLost(@NonNull Network network) {
+                super.onLost(network);
+                checkConnectivity();
+                Mobileserver.usingMobileDataChanged();
+            }
+
+            @Override
+            public void onAvailable(@NonNull Network network) {
+                super.onAvailable(network);
+                checkConnectivity();
+                Mobileserver.usingMobileDataChanged();
+            }
+        };
+    }
+
+    public void registerNetworkCallback() {
+        if (connectivityManager == null) {
+            return;
+        }
+
+        // Register the network callback to listen for changes in network capabilities.
+        // It needs to be unregistered when the app is in background to avoid resources consumpion.
+        // See https://developer.android.com/reference/android/net/ConnectivityManager#registerNetworkCallback(android.net.NetworkRequest,%20android.net.ConnectivityManager.NetworkCallback)
+        connectivityManager.registerDefaultNetworkCallback(networkCallback);
+    }
+
+    public void unregisterNetworkCallback() {
+        if (connectivityManager != null && networkCallback != null) {
+            connectivityManager.unregisterNetworkCallback(networkCallback);
+        }
+    }
+
+    // Fetches the active network and verifies if that provides internet access.
+    public void checkConnectivity() {
+        Network activeNetwork = connectivityManager.getActiveNetwork();
+        // If there is no active network (e.g. airplane mode), there is no check to perform.
+        if (activeNetwork == null) {
+            Util.log("checkConnectivity: active network null");
+            Mobileserver.setOnline(false);
+            return;
+        }
+        NetworkCapabilities capabilities = connectivityManager.getNetworkCapabilities(activeNetwork);
+        Mobileserver.setOnline(hasInternetConnectivity(capabilities));
+    }
+
+    private boolean hasInternetConnectivity(NetworkCapabilities capabilities) {
+        Util.log("hasInternetConnectivity");
+        if (capabilities == null) {
+            Util.log("hasInternetConnectivity: null capabilities");
+            return false;
+        }
+
+        boolean validated = capabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED);
+        Util.log("Has internet connectivity: " + validated);
+        return validated;
+    }
+
+    // if usingMobileData returns true, a banner will be desplayed in the app to warn about
+    // possible network data consumption.
+    public boolean usingMobileData() {
+        if (connectivityManager == null) {
+            return false;
+        }
+
+        NetworkCapabilities capabilities = connectivityManager.getNetworkCapabilities(connectivityManager.getActiveNetwork());
+        boolean mobileData = capabilities != null && capabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR);
+        Util.log("Using mobile data: " + mobileData);
+        return mobileData;
+    }
+}
