Add DnsResolverServiceManager

Add DnsResolverServiceManager to obtain android.net.IDnsResolver
IBinder for incoming connectivity service mainline.

Bug: 170598012
Test: atest FrameworksNetTests
Change-Id: Ibd7a678ceaaa550ff3d8eff1d0c4d3a5073b5527

2 files changed, 67 insertions, 0 deletions

diff --git a/core/api/system-current.txt b/core/api/system-current.txt
index de8e18046a39..6333b5f024f8 100644
--- a/core/api/system-current.txt
+++ b/core/api/system-current.txt
@@ -6006,6 +6006,10 @@ package android.net {
     method @Deprecated public void onUpstreamChanged(@Nullable android.net.Network);
   }
 
+  public class DnsResolverServiceManager {
+    method @NonNull @RequiresPermission(android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK) public static android.os.IBinder getService(@NonNull android.content.Context);
+  }
+
   public class EthernetManager {
     method @NonNull @RequiresPermission(anyOf={android.Manifest.permission.NETWORK_STACK, android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK}) public android.net.EthernetManager.TetheredInterfaceRequest requestTetheredInterface(@NonNull java.util.concurrent.Executor, @NonNull android.net.EthernetManager.TetheredInterfaceCallback);
   }
diff --git a/core/java/android/net/DnsResolverServiceManager.java b/core/java/android/net/DnsResolverServiceManager.java
new file mode 100644
index 000000000000..15973224f10b
--- /dev/null
+++ b/core/java/android/net/DnsResolverServiceManager.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package android.net;
+
+import android.annotation.NonNull;
+import android.annotation.RequiresPermission;
+import android.annotation.SystemApi;
+import android.content.Context;
+import android.os.IBinder;
+import android.os.ServiceManager;
+
+import java.util.Objects;
+
+/**
+ * Provides a way to obtain the DnsResolver binder objects.
+ *
+ * @hide
+ */
+@SystemApi
+public class DnsResolverServiceManager {
+    /**
+     * Name to retrieve a {@link android.net.IDnsResolver} IBinder.
+     */
+    private static final String DNS_RESOLVER_SERVICE = "dnsresolver";
+
+    private DnsResolverServiceManager() {}
+
+    /**
+     * Get an {@link IBinder} representing the DnsResolver stable AIDL interface
+     *
+     * @param context the context for permission check.
+     * @return {@link android.net.IDnsResolver} IBinder.
+     */
+    @NonNull
+    @RequiresPermission(NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK)
+    public static IBinder getService(@NonNull final Context context) {
+        Objects.requireNonNull(context);
+        context.enforceCallingOrSelfPermission(NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK,
+                "DnsResolverServiceManager");
+        try {
+            return ServiceManager.getServiceOrThrow(DNS_RESOLVER_SERVICE);
+        } catch (ServiceManager.ServiceNotFoundException e) {
+            // Catch ServiceManager#ServiceNotFoundException and rethrow IllegalStateException
+            // because ServiceManager#ServiceNotFoundException is @hide so that it can't be listed
+            // on the system api. Thus, rethrow IllegalStateException if dns resolver service cannot
+            // be found.
+            throw new IllegalStateException("Cannot find dns resolver service.");
+        }
+    }
+}