Bind only the socket we use for UDP broadcast, not the process

src/org/kde/kdeconnect/Backends/BaseLinkProvider.java

@@ -6,7 +6,10 @@
 
 package org.kde.kdeconnect.Backends;
 
+import android.net.Network;
+
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 import java.util.concurrent.CopyOnWriteArrayList;
 
@@ -49,7 +52,7 @@ public abstract class BaseLinkProvider {
 
     public abstract void onStart();
     public abstract void onStop();
-    public abstract void onNetworkChange();
+    public abstract void onNetworkChange(@Nullable Network network);
     public abstract String getName();
 
 }

src/org/kde/kdeconnect/Backends/BluetoothBackend/BluetoothLinkProvider.java

@@ -14,10 +14,13 @@ import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
+import android.net.Network;
 import android.os.Parcelable;
 import android.util.Base64;
 import android.util.Log;
 
+import androidx.annotation.Nullable;
+
 import org.apache.commons.io.IOUtils;
 import org.kde.kdeconnect.Backends.BaseLinkProvider;
 import org.kde.kdeconnect.Device;
@@ -107,7 +110,7 @@ public class BluetoothLinkProvider extends BaseLinkProvider {
     }
 
     @Override
-    public void onNetworkChange() {
+    public void onNetworkChange(@Nullable Network network) {
         onStop();
         onStart();
     }

src/org/kde/kdeconnect/Backends/LanBackend/LanLinkProvider.java

@@ -8,9 +8,12 @@ package org.kde.kdeconnect.Backends.LanBackend;
 
 import android.content.Context;
 import android.content.SharedPreferences;
+import android.net.Network;
+import android.os.Build;
 import android.preference.PreferenceManager;
 import android.util.Log;
 
+import androidx.annotation.Nullable;
 import androidx.annotation.WorkerThread;
 
 import org.json.JSONException;
@@ -301,7 +304,7 @@ public class LanLinkProvider extends BaseLinkProvider {
                     });
                 } catch (IOException e) {
                     Log.e("LanLinkProvider", "UdpReceive exception", e);
-                    onNetworkChange(); // Trigger a UDP broadcast to try to get them to connect to us instead
+                    onNetworkChange(null); // Trigger a UDP broadcast to try to get them to connect to us instead
                 }
             }
             Log.w("UdpListener", "Stopping UDP listener");
@@ -355,7 +358,7 @@ public class LanLinkProvider extends BaseLinkProvider {
         throw new RuntimeException("This should not be reachable");
     }
 
-    private void broadcastUdpIdentityPacket() {
+    private void broadcastUdpIdentityPacket(@Nullable Network network) {
         SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
         if (!preferences.getBoolean(SettingsFragment.KEY_UDP_BROADCAST_ENABLED, true)) {
             Log.i("LanLinkProvider", "UDP broadcast is disabled in settings. Skipping.");
@@ -385,12 +388,12 @@ public class LanLinkProvider extends BaseLinkProvider {
                 return;
             }
 
-            sendUdpIdentityPacket(ipList);
+            sendUdpIdentityPacket(ipList, network);
         });
     }
 
     @WorkerThread
-    public void sendUdpIdentityPacket(List<InetAddress> ipList) {
+    public void sendUdpIdentityPacket(List<InetAddress> ipList, @Nullable Network network) {
         if (tcpServer == null || !tcpServer.isBound()) {
             Log.i("LanLinkProvider", "Won't broadcast UDP packet if TCP socket is not ready yet");
             return;
@@ -411,6 +414,14 @@ public class LanLinkProvider extends BaseLinkProvider {
         DatagramSocket socket;
         try {
             socket = new DatagramSocket();
+            if (network != null && Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) {
+                try {
+                    network.bindSocket(socket);
+                } catch (IOException e) {
+                    Log.w("LanLinkProvider", "Couldn't bind socket to the network");
+                    e.printStackTrace();
+                }
+            }
             socket.setReuseAddress(true);
             socket.setBroadcast(true);
         } catch (SocketException e) {
@@ -443,19 +454,19 @@ public class LanLinkProvider extends BaseLinkProvider {
             mdnsDiscovery.startDiscovering();
             mdnsDiscovery.startAnnouncing();
 
-            broadcastUdpIdentityPacket();
+            broadcastUdpIdentityPacket(null);
         }
     }
 
     @Override
-    public void onNetworkChange() {
+    public void onNetworkChange(@Nullable Network network) {
         if (System.currentTimeMillis() < lastBroadcast + delayBetweenBroadcasts) {
             Log.i("LanLinkProvider", "onNetworkChange: relax cowboy");
             return;
         }
         lastBroadcast = System.currentTimeMillis();
 
-        broadcastUdpIdentityPacket();
+        broadcastUdpIdentityPacket(network);
         mdnsDiscovery.stopDiscovering();
         mdnsDiscovery.startDiscovering();
     }

src/org/kde/kdeconnect/Backends/LanBackend/MdnsDiscovery.java

@@ -216,7 +216,7 @@ public class MdnsDiscovery {
 
                 // Let the LanLinkProvider handle the connection
                 InetAddress remoteAddress = serviceInfo.getHost();
-                lanLinkProvider.sendUdpIdentityPacket(Collections.singletonList(remoteAddress));
+                lanLinkProvider.sendUdpIdentityPacket(Collections.singletonList(remoteAddress), null);
             }
         };
     }

src/org/kde/kdeconnect/Backends/LoopbackBackend/LoopbackLinkProvider.java

@@ -7,6 +7,9 @@
 package org.kde.kdeconnect.Backends.LoopbackBackend;
 
 import android.content.Context;
+import android.net.Network;
+
+import androidx.annotation.Nullable;
 
 import org.kde.kdeconnect.Backends.BaseLinkProvider;
 
@@ -20,7 +23,7 @@ public class LoopbackLinkProvider extends BaseLinkProvider {
 
     @Override
     public void onStart() {
-        onNetworkChange();
+        onNetworkChange(null);
     }
 
     @Override
@@ -28,7 +31,7 @@ public class LoopbackLinkProvider extends BaseLinkProvider {
     }
 
     @Override
-    public void onNetworkChange() {
+    public void onNetworkChange(@Nullable Network network) {
         LoopbackLink link = new LoopbackLink(context, this);
         onConnectionReceived(link);
     }

src/org/kde/kdeconnect/BackgroundService.java

@@ -25,6 +25,7 @@ import android.os.IBinder;
 import android.text.TextUtils;
 import android.util.Log;
 
+import androidx.annotation.Nullable;
 import androidx.core.app.NotificationCompat;
 import androidx.core.content.ContextCompat;
 import androidx.lifecycle.LiveData;
@@ -84,14 +85,14 @@ public class BackgroundService extends Service {
 //        linkProviders.add(new BluetoothLinkProvider(this));
     }
 
-    public void onNetworkChange() {
+    public void onNetworkChange(@Nullable Network network) {
         if (!initialized) {
             Log.d("KDE/BackgroundService", "ignoring onNetworkChange called before the service is initialized");
             return;
         }
         Log.d("KDE/BackgroundService", "onNetworkChange");
         for (BaseLinkProvider a : linkProviders) {
-            a.onNetworkChange();
+            a.onNetworkChange(network);
         }
     }
 
@@ -130,18 +131,8 @@ public class BackgroundService extends Service {
         cm.registerNetworkCallback(networkRequestBuilder.build(), new ConnectivityManager.NetworkCallback() {
             @Override
             public void onAvailable(Network network) {
-                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
-                    cm.bindProcessToNetwork(network);
-                } else {
-                    try {
-                        ConnectivityManager.setProcessDefaultNetwork(network);
-                    } catch (IllegalStateException e) {
-                        Log.d("KDE/BackgroundService", "Failed to bind process to network", e);
-                        return;
-                    }
-                }
                 connectedToNonCellularNetwork.postValue(true);
-                onNetworkChange();
+                onNetworkChange(network);
             }
             @Override
             public void onLost(Network network) {
@@ -285,7 +276,7 @@ public class BackgroundService extends Service {
             }
         }
         if (intent != null && intent.getBooleanExtra("refresh", false)) {
-            onNetworkChange();
+            onNetworkChange(null);
         }
         return Service.START_STICKY;
     }