Add callback registration in ConnectivityService.

ConnectivityDiagnosticsManager will send callbacks to
ConnectivityService for registering and unregistering them with the
system. ConnectivityService needs to do the processing for persisting
(and deleting) these callbacks on the ConnectivityService Thread, so
messages are sent to the Connectivity Diagnostics  Handler, which runs
on the ConnectivityService Thread.

Bug: 146444622
Bug: 143187964
Bug: 147848028
Test: compiles
Test: atest FrameworksNetTests
Change-Id: Ia5c8f90a60c050504e8676de9564a7607a9b03bc

core/java/android/net/ConnectivityDiagnosticsManager.java

@@ -25,13 +25,16 @@ import android.os.Binder;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.os.PersistableBundle;
+import android.os.RemoteException;
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.Preconditions;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.util.Map;
 import java.util.Objects;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Executor;
 
 /**
@@ -57,6 +60,11 @@ import java.util.concurrent.Executor;
  * </ul>
  */
 public class ConnectivityDiagnosticsManager {
+    /** @hide */
+    @VisibleForTesting
+    public static final Map<ConnectivityDiagnosticsCallback, ConnectivityDiagnosticsBinder>
+            sCallbacks = new ConcurrentHashMap<>();
+
     private final Context mContext;
     private final IConnectivityManager mService;
 
@@ -646,9 +654,9 @@ public class ConnectivityDiagnosticsManager {
      * <p>If a registering app loses its relevant permissions, any callbacks it registered will
      * silently stop receiving callbacks.
      *
-     * <p>Each register() call <b>MUST</b> use a unique ConnectivityDiagnosticsCallback instance. If
-     * a single instance is registered with multiple NetworkRequests, an IllegalArgumentException
-     * will be thrown.
+     * <p>Each register() call <b>MUST</b> use a ConnectivityDiagnosticsCallback instance that is
+     * not currently registered. If a ConnectivityDiagnosticsCallback instance is registered with
+     * multiple NetworkRequests, an IllegalArgumentException will be thrown.
      *
      * @param request The NetworkRequest that will be used to match with Networks for which
      *     callbacks will be fired
@@ -657,15 +665,21 @@ public class ConnectivityDiagnosticsManager {
      *     System
      * @throws IllegalArgumentException if the same callback instance is registered with multiple
      *     NetworkRequests
-     * @throws SecurityException if the caller does not have appropriate permissions to register a
-     *     callback
      */
     public void registerConnectivityDiagnosticsCallback(
             @NonNull NetworkRequest request,
             @NonNull Executor e,
             @NonNull ConnectivityDiagnosticsCallback callback) {
-        // TODO(b/143187964): implement ConnectivityDiagnostics functionality
-        throw new UnsupportedOperationException("registerCallback() not supported yet");
+        final ConnectivityDiagnosticsBinder binder = new ConnectivityDiagnosticsBinder(callback, e);
+        if (sCallbacks.putIfAbsent(callback, binder) != null) {
+            throw new IllegalArgumentException("Callback is currently registered");
+        }
+
+        try {
+            mService.registerConnectivityDiagnosticsCallback(binder, request);
+        } catch (RemoteException exception) {
+            exception.rethrowFromSystemServer();
+        }
     }
 
     /**
@@ -678,7 +692,15 @@ public class ConnectivityDiagnosticsManager {
      */
     public void unregisterConnectivityDiagnosticsCallback(
             @NonNull ConnectivityDiagnosticsCallback callback) {
-        // TODO(b/143187964): implement ConnectivityDiagnostics functionality
-        throw new UnsupportedOperationException("registerCallback() not supported yet");
+        // unconditionally removing from sCallbacks prevents race conditions here, since remove() is
+        // atomic.
+        final ConnectivityDiagnosticsBinder binder = sCallbacks.remove(callback);
+        if (binder == null) return;
+
+        try {
+            mService.unregisterConnectivityDiagnosticsCallback(binder);
+        } catch (RemoteException exception) {
+            exception.rethrowFromSystemServer();
+        }
     }
 }