From 3b7dd6e87c9600d184e9bfe59cf53500d5639a12 Mon Sep 17 00:00:00 2001
From: brad112358 <brad112358@gmail.com>
Date: Tue, 24 Nov 2020 14:13:23 -0600
Subject: [PATCH] Take MulticastLock on Android to ensure broadcast packets can
 be received (#9199)

* Take MulticastLock on Android to ensure broadcast packets can be received.  This may belong in Qt for Android.  See QTBUG-73138

* Use a more descriptive name for the WiFiManager Multicast Lock
---
 android/AndroidManifest.xml                          |  3 +++
 .../src/org/mavlink/qgroundcontrol/QGCActivity.java  | 20 +++++++++++++++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/android/AndroidManifest.xml b/android/AndroidManifest.xml
index 93bb77f..82a692f 100644
--- a/android/AndroidManifest.xml
+++ b/android/AndroidManifest.xml
@@ -54,6 +54,9 @@
     <!-- Needed to keep working while 'asleep' -->
     <uses-permission android:name="android.permission.WAKE_LOCK"/>
 
+    <!-- Need MulticastLock to receive broadcast UDP packets  -->
+    <uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE"/>
+
     <!-- The following comment will be replaced upon deployment with default permissions based on the dependencies of the application.
          Remove the comment if you do not require these default permissions. -->
     <!-- %%INSERT_PERMISSIONS -->
diff --git a/android/src/org/mavlink/qgroundcontrol/QGCActivity.java b/android/src/org/mavlink/qgroundcontrol/QGCActivity.java
index cf47c78..14fb760 100644
--- a/android/src/org/mavlink/qgroundcontrol/QGCActivity.java
+++ b/android/src/org/mavlink/qgroundcontrol/QGCActivity.java
@@ -52,6 +52,7 @@ import android.hardware.usb.UsbManager;
 import android.widget.Toast;
 import android.util.Log;
 import android.os.PowerManager;
+import android.net.wifi.WifiManager;
 import android.os.Bundle;
 import android.app.PendingIntent;
 import android.view.WindowManager;
@@ -76,7 +77,8 @@ public class QGCActivity extends QtActivity
     private static PendingIntent                        _usbPermissionIntent = null;
     private TaiSync                                     taiSync = null;
     private Timer                                       probeAccessoriesTimer = null;
-
+    private static WifiManager.MulticastLock            _wifiMulticastLock;
+    
     public static Context m_context;
 
     private final static ExecutorService m_Executor = Executors.newSingleThreadExecutor();
@@ -222,6 +224,18 @@ public class QGCActivity extends QtActivity
         // Create intent for usb permission request
         _usbPermissionIntent = PendingIntent.getBroadcast(_instance, 0, new Intent(ACTION_USB_PERMISSION), 0);
 
+	// Workaround for QTBUG-73138
+	if (_wifiMulticastLock == null)
+            {
+                WifiManager wifi = (WifiManager) _instance.getSystemService(Context.WIFI_SERVICE);
+                _wifiMulticastLock = wifi.createMulticastLock("QGroundControl");
+                _wifiMulticastLock.setReferenceCounted(true);
+            }
+
+	_wifiMulticastLock.acquire();
+	Log.d(TAG, "Multicast lock: " + _wifiMulticastLock.toString());
+
+
         try {
             taiSync = new TaiSync();
 
@@ -259,6 +273,10 @@ public class QGCActivity extends QtActivity
         }
         unregisterReceiver(mOpenAccessoryReceiver);
         try {
+            if (_wifiMulticastLock != null) {
+                _wifiMulticastLock.release();
+                Log.d(TAG, "Multicast lock released.");
+            }
             if(_wakeLock != null) {
                 _wakeLock.release();
             }