Add InetAddressCompat

Although the InetAddress symbols used by Connectivity are stable core
platform API, and should be usable, the core_current stubs are not yet
part of the module_current API.
Until that is fixed, add an InetAddressCompat utility that calls the
three static methods by reflection.

Test: atest FrameworksNetTests CtsNetTestCases
Bug: 183097033
Change-Id: I797009aeff1d39ae2dc06ef69d2e235689b43c89

framework/src/android/net/ConnectivityManager.java

@@ -4639,7 +4639,7 @@ public class ConnectivityManager {
                 Log.e(TAG, "Can't set proxy properties", e);
             }
             // Must flush DNS cache as new network may have different DNS resolutions.
-            InetAddress.clearDnsCache();
+            InetAddressCompat.clearDnsCache();
             // Must flush socket pool as idle sockets will be bound to previous network and may
             // cause subsequent fetches to be performed on old network.
             NetworkEventDispatcher.getInstance().onNetworkConfigurationChanged();

framework/src/android/net/InetAddressCompat.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2021 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.util.Log;
+
+import java.lang.reflect.InvocationTargetException;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+/**
+ * Compatibility utility for InetAddress core platform APIs.
+ *
+ * Connectivity has access to such APIs, but they are not part of the module_current stubs yet
+ * (only core_current). Most stable core platform APIs are included manually in the connectivity
+ * build rules, but because InetAddress is also part of the base java SDK that is earlier on the
+ * classpath, the extra core platform APIs are not seen.
+ *
+ * TODO (b/183097033): remove this utility as soon as core_current is part of module_current
+ * @hide
+ */
+public class InetAddressCompat {
+
+    /**
+     * @see InetAddress#clearDnsCache()
+     */
+    public static void clearDnsCache() {
+        try {
+            InetAddress.class.getMethod("clearDnsCache").invoke(null);
+        } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
+            Log.wtf(InetAddressCompat.class.getSimpleName(), "Error clearing DNS cache", e);
+        }
+    }
+
+    /**
+     * @see InetAddress#getAllByNameOnNet(String, int)
+     */
+    public static InetAddress[] getAllByNameOnNet(String host, int netId) throws
+            UnknownHostException {
+        try {
+            return (InetAddress[]) InetAddress.class.getMethod("getAllByNameOnNet",
+                    String.class, int.class).invoke(null, host, netId);
+        } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
+            Log.wtf(InetAddressCompat.class.getSimpleName(), "Error calling getAllByNameOnNet", e);
+            throw new IllegalStateException("Error querying via getAllNameOnNet", e);
+        }
+    }
+
+    /**
+     * @see InetAddress#getByNameOnNet(String, int)
+     */
+    public static InetAddress getByNameOnNet(String host, int netId) throws
+            UnknownHostException {
+        try {
+            return (InetAddress) InetAddress.class.getMethod("getByNameOnNet",
+                    String.class, int.class).invoke(null, host, netId);
+        } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
+            Log.wtf(InetAddressCompat.class.getSimpleName(), "Error calling getAllByNameOnNet", e);
+            throw new IllegalStateException("Error querying via getByNameOnNet", e);
+        }
+    }
+}

framework/src/android/net/Network.java

@@ -142,7 +142,7 @@ public class Network implements Parcelable {
      * @throws UnknownHostException if the address lookup fails.
      */
     public InetAddress[] getAllByName(String host) throws UnknownHostException {
-        return InetAddress.getAllByNameOnNet(host, getNetIdForResolv());
+        return InetAddressCompat.getAllByNameOnNet(host, getNetIdForResolv());
     }
 
     /**
@@ -155,7 +155,7 @@ public class Network implements Parcelable {
      *             if the address lookup fails.
      */
     public InetAddress getByName(String host) throws UnknownHostException {
-        return InetAddress.getByNameOnNet(host, getNetIdForResolv());
+        return InetAddressCompat.getByNameOnNet(host, getNetIdForResolv());
     }
 
     /**