Private DNS: Set mode in an async task

The Private DNS mode must not be set on the UI thread, as it could
trigger a network host lookup (in case a hostname is specified).

Perform it in a background task instead.

Additionally, stop using reflection utils since TestDPC now builds
against Q SDK.

Bug: 120416121
Test: Manual, set mode from TestDPC
Change-Id: I4e81541da8e15df7e966d8a25903d757d24caf8b

Author: eranmes

app/src/main/java/com/afwsamples/testdpc/policy/networking/PrivateDnsModeFragment.java

@@ -33,7 +33,6 @@
 
 import com.afwsamples.testdpc.DeviceAdminReceiver;
 import com.afwsamples.testdpc.R;
-import com.afwsamples.testdpc.common.ReflectionUtil;
 
 @TargetApi(29)
 public class PrivateDnsModeFragment extends Fragment implements View.OnClickListener,
@@ -122,10 +121,9 @@ private void updateSelectedMode(int checkedId) {
 
     private int getPrivateDnsMode() {
         try {
-            return (Integer) ReflectionUtil.invoke(
-                    mDpm, "getGlobalPrivateDnsMode",
+            return mDpm.getGlobalPrivateDnsMode(
                     DeviceAdminReceiver.getComponentName(getActivity()));
-        } catch (ReflectionUtil.ReflectionIsTemporaryException e) {
+        } catch (SecurityException e) {
             Log.w(TAG, "Failure getting current mode", e);
         }
 
@@ -134,10 +132,9 @@ private int getPrivateDnsMode() {
 
     private String getPrivateDnsHost() {
         try {
-            return (String) ReflectionUtil.invoke(
-                    mDpm, "getGlobalPrivateDnsHost",
+            return mDpm.getGlobalPrivateDnsHost(
                     DeviceAdminReceiver.getComponentName(getActivity()));
-        } catch (ReflectionUtil.ReflectionIsTemporaryException e) {
+        } catch (SecurityException e) {
             Log.w(TAG, "Failure getting host", e);
         }
 
@@ -146,23 +143,12 @@ private String getPrivateDnsHost() {
 
     private void setPrivateDnsMode(int mode, String resolver) {
         Log.w(TAG, String.format("Setting mode %d host %s", mSelectedMode, resolver));
-        try {
-            ReflectionUtil.invoke(
-                    mDpm, "setGlobalPrivateDns",
-                    new Class[]{ComponentName.class, int.class, String.class},
-                    DeviceAdminReceiver.getComponentName(getActivity()),
-                    mode,
-                    resolver);
-            Toast.makeText(getActivity(), R.string.setting_private_dns_succeess,
-                    Toast.LENGTH_LONG).show();
-        } catch (ReflectionUtil.ReflectionIsTemporaryException e) {
-            Log.w(TAG, "Failed to invoke, cause", e);
-
-            // This is the real exception.
-            Throwable causeOfCause = e.getCause().getCause();
-
-            Toast.makeText(getActivity(),
-                    "Failure: " + causeOfCause.getMessage(), Toast.LENGTH_LONG).show();
-        }
+
+        final ComponentName component = DeviceAdminReceiver.getComponentName(getActivity());
+        new SetPrivateDnsTask(
+                mDpm, component, mode, resolver, (int msgId, Object... args) -> {
+                    Toast.makeText(getActivity(), getString(msgId, args),
+                            Toast.LENGTH_LONG).show();
+                }).execute(new Void[0]);
     }
 }

app/src/main/java/com/afwsamples/testdpc/policy/networking/SetPrivateDnsTask.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2018 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 com.afwsamples.testdpc.policy.networking;
+
+import android.annotation.TargetApi;
+import android.app.admin.DevicePolicyManager;
+import android.content.ComponentName;
+import android.os.AsyncTask;
+import android.util.Log;
+
+import com.afwsamples.testdpc.policy.keymanagement.ShowToastCallback;
+import com.afwsamples.testdpc.R;
+
+@TargetApi(29)
+final class SetPrivateDnsTask extends AsyncTask<Void, Void, String> {
+    public static final String TAG = "Networking";
+    private final ShowToastCallback mCallback;
+    private final DevicePolicyManager mDpm;
+    private final ComponentName mComponent;
+    private final int mMode;
+    private final String mResolver;
+
+    public SetPrivateDnsTask(
+            DevicePolicyManager dpm, ComponentName component, int mode, String resolver,
+            ShowToastCallback callback) {
+        mDpm = dpm;
+        mComponent = component;
+        mCallback = callback;
+        mMode = mode;
+        mResolver = resolver;
+    }
+
+    @Override
+    protected String doInBackground(Void... params) {
+        try {
+            mDpm.setGlobalPrivateDns(mComponent, mMode, mResolver);
+            return null;
+        } catch (SecurityException | IllegalArgumentException e) {
+            Log.w(TAG, "Failed to invoke, cause", e);
+            return e.getMessage();
+        }
+    }
+
+    @Override
+    protected void onPostExecute(String error) {
+        if (error == null) {
+            mCallback.showToast(R.string.setting_private_dns_succeess);
+        } else {
+            mCallback.showToast(R.string.setting_private_dns_failure, error);
+        }
+    }
+}

app/src/main/res/values/strings.xml

@@ -774,6 +774,7 @@
     <string name="private_dns_mode_unknown">Unknown</string>
     <string name="private_dns_mode_apply">Set</string>
     <string name="setting_private_dns_succeess">Success setting Private DNS</string>
+    <string name="setting_private_dns_failure">FAILED: %s</string>
 
     <!--  Strings for data usage -->
     <string name="data_usage">Data usage</string>