Use TetheringEventCallback when appropriate

mobile/src/main/java/be/mygod/vpnhotspot/TetheringService.kt

@@ -1,20 +1,16 @@
 package be.mygod.vpnhotspot
 
 import android.content.Intent
-import android.content.IntentFilter
 import be.mygod.vpnhotspot.App.Companion.app
 import be.mygod.vpnhotspot.net.Routing
 import be.mygod.vpnhotspot.net.TetherType
 import be.mygod.vpnhotspot.net.TetheringManager
-import be.mygod.vpnhotspot.net.TetheringManager.tetheredIfaces
 import be.mygod.vpnhotspot.net.monitor.IpNeighbourMonitor
 import be.mygod.vpnhotspot.util.Event0
-import be.mygod.vpnhotspot.util.broadcastReceiver
-import be.mygod.vpnhotspot.util.ensureReceiverUnregistered
 import kotlinx.coroutines.*
 import java.util.concurrent.ConcurrentHashMap
 
-class TetheringService : IpNeighbourMonitoringService(), CoroutineScope {
+class TetheringService : IpNeighbourMonitoringService(), TetheringManager.TetheringEventCallback, CoroutineScope {
     companion object {
         const val EXTRA_ADD_INTERFACES = "interface.add"
         const val EXTRA_ADD_INTERFACE_MONITOR = "interface.add.monitor"
@@ -47,11 +43,14 @@ class TetheringService : IpNeighbourMonitoringService(), CoroutineScope {
     override val coroutineContext = dispatcher + Job()
     private val binder = Binder()
     private val downstreams = ConcurrentHashMap<String, Downstream>()
-    private var receiverRegistered = false
-    private val receiver = broadcastReceiver { _, intent ->
+    private var callbackRegistered = false
+    override val activeIfaces get() = downstreams.values.filter { it.started }.map { it.downstream }
+    override val inactiveIfaces get() = downstreams.values.filter { !it.started }.map { it.downstream }
+
+    override fun onTetheredInterfacesChanged(interfaces: List<String?>) {
         launch {
             val toRemove = downstreams.toMutableMap()   // make a copy
-            for (iface in intent.tetheredIfaces ?: return@launch) {
+            for (iface in interfaces) {
                 val downstream = toRemove.remove(iface) ?: continue
                 if (downstream.monitor) downstream.start()
             }
@@ -62,8 +61,6 @@ class TetheringService : IpNeighbourMonitoringService(), CoroutineScope {
             onDownstreamsChangedLocked()
         }
     }
-    override val activeIfaces get() = downstreams.values.filter { it.started }.map { it.downstream }
-    override val inactiveIfaces get() = downstreams.values.filter { !it.started }.map { it.downstream }
 
     private fun onDownstreamsChangedLocked() {
         if (downstreams.isEmpty()) {
@@ -71,9 +68,9 @@ class TetheringService : IpNeighbourMonitoringService(), CoroutineScope {
             ServiceNotification.stopForeground(this)
             stopSelf()
         } else {
-            if (!receiverRegistered) {
-                receiverRegistered = true
-                registerReceiver(receiver, IntentFilter(TetheringManager.ACTION_TETHER_STATE_CHANGED))
+            if (!callbackRegistered) {
+                callbackRegistered = true
+                TetheringManager.registerTetheringEventCallbackCompat(this, this)
                 IpNeighbourMonitor.registerCallback(this)
             }
             updateNotification()
@@ -118,10 +115,10 @@ class TetheringService : IpNeighbourMonitoringService(), CoroutineScope {
     }
 
     private fun unregisterReceiver() {
-        if (receiverRegistered) {
-            ensureReceiverUnregistered(receiver)
+        if (callbackRegistered) {
+            TetheringManager.unregisterTetheringEventCallbackCompat(this, this)
             IpNeighbourMonitor.unregisterCallback(this)
-            receiverRegistered = false
+            callbackRegistered = false
         }
     }
 }

mobile/src/main/java/be/mygod/vpnhotspot/net/TetheringManager.kt

@@ -1,6 +1,9 @@
 package be.mygod.vpnhotspot.net
 
+import android.content.BroadcastReceiver
+import android.content.Context
 import android.content.Intent
+import android.content.IntentFilter
 import android.content.pm.PackageManager
 import android.net.ConnectivityManager
 import android.net.LinkAddress
@@ -12,6 +15,8 @@ import androidx.collection.SparseArrayCompat
 import androidx.core.os.BuildCompat
 import be.mygod.vpnhotspot.App.Companion.app
 import be.mygod.vpnhotspot.R
+import be.mygod.vpnhotspot.util.broadcastReceiver
+import be.mygod.vpnhotspot.util.ensureReceiverUnregistered
 import com.android.dx.stock.ProxyBuilder
 import timber.log.Timber
 import java.lang.ref.WeakReference
@@ -185,6 +190,8 @@ object TetheringManager {
     @get:RequiresApi(30)
     private val stopTethering by lazy { clazz.getDeclaredMethod("stopTethering", Int::class.java) }
 
+    private fun Handler?.makeExecutor() = Executor { if (this == null) it.run() else post(it) }
+
     /**
      * Runs tether provisioning for the given type if needed and then starts tethering if
      * the check succeeds. If no carrier provisioning is required for tethering, tethering is
@@ -228,7 +235,6 @@ object TetheringManager {
                 }
                 build.invoke(this)
             }
-            val executor = Executor { if (handler == null) it.run() else handler.post(it) }
             val proxy = Proxy.newProxyInstance(interfaceStartTetheringCallback.classLoader,
                     arrayOf(interfaceStartTetheringCallback)) { proxy, method, args ->
                 @Suppress("NAME_SHADOWING") val callback = reference.get()
@@ -249,7 +255,7 @@ object TetheringManager {
                     }
                 }
             }
-            startTethering.invoke(instance, request, executor, proxy)
+            startTethering.invoke(instance, request, handler.makeExecutor(), proxy)
             return
         } catch (e: InvocationTargetException) {
             Timber.w(e, "Unable to invoke TetheringManager.startTethering, falling back to ConnectivityManager")
@@ -492,6 +498,31 @@ object TetheringManager {
         unregisterTetheringEventCallback.invoke(instance, proxy)
     }
 
+    /**
+     * [registerTetheringEventCallback] in a backwards compatible way.
+     *
+     * Only [TetheringEventCallback.onTetheredInterfacesChanged] is supported on API 29-.
+     */
+    fun registerTetheringEventCallbackCompat(context: Context, callback: TetheringEventCallback) {
+        if (BuildCompat.isAtLeastR()) {
+            registerTetheringEventCallback(null.makeExecutor(), callback)
+        } else synchronized(callbackMap) {
+            callbackMap.computeIfAbsent(callback) {
+                broadcastReceiver { _, intent ->
+                    callback.onTetheredInterfacesChanged(intent.tetheredIfaces ?: return@broadcastReceiver)
+                }.also { context.registerReceiver(it, IntentFilter(ACTION_TETHER_STATE_CHANGED)) }
+            }
+        }
+    }
+    fun unregisterTetheringEventCallbackCompat(context: Context, callback: TetheringEventCallback) {
+        if (BuildCompat.isAtLeastR()) {
+            unregisterTetheringEventCallback(callback)
+        } else {
+            val receiver = synchronized(callbackMap) { callbackMap.remove(callback) } ?: return
+            context.ensureReceiverUnregistered(receiver as BroadcastReceiver)
+        }
+    }
+
     /**
      * Get a more detailed error code after a Tethering or Untethering
      * request asynchronously failed.