Trigger NetworkCallback events when private DNS usage has changed.

Relies on events sent from netd in aosp/578162.

Test: Added tests to ConnectivityServiceTest. Added a new test
class DnsManagerTest. Built a simple app that appears to
receive onLinkProperties events correctly upon manual changes
to the private DNS settings on a Pixel.
Bug: 71828272

Merged-In: I1e6c54ba016f6a165a302bd135a29d9332aaa235
Merged-In: I7705412803fb9aa707a18ae5a1c50292e084d851
Change-Id: I3223c1285a73d5d531c5051ce70007857caa57e3
(cherry picked from commit 7301aa4140baefb549a737f033fc512e87c55692)
diff --git a/tests/net/java/com/android/server/connectivity/DnsManagerTest.java b/tests/net/java/com/android/server/connectivity/DnsManagerTest.java
new file mode 100644
index 0000000..bcd8bf3
--- /dev/null
+++ b/tests/net/java/com/android/server/connectivity/DnsManagerTest.java
@@ -0,0 +1,201 @@
+/*
+ * 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.android.server.connectivity;
+
+import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_OFF;
+import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_OPPORTUNISTIC;
+import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_PROVIDER_HOSTNAME;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.when;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.os.INetworkManagementService;
+import android.provider.Settings;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+import android.test.mock.MockContentResolver;
+
+import com.android.internal.util.test.FakeSettingsProvider;
+import com.android.server.connectivity.MockableSystemProperties;
+
+import java.net.InetAddress;
+
+import org.junit.runner.RunWith;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+/**
+ * Tests for {@link DnsManager}.
+ *
+ * Build, install and run with:
+ *  runtest frameworks-net -c com.android.server.connectivity.DnsManagerTest
+ */
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class DnsManagerTest {
+    static final int TEST_NETID = 100;
+    static final int TEST_NETID_ALTERNATE = 101;
+    static final int TEST_NETID_UNTRACKED = 102;
+    final boolean IS_DEFAULT = true;
+    final boolean NOT_DEFAULT = false;
+
+    DnsManager mDnsManager;
+    MockContentResolver mContentResolver;
+
+    @Mock Context mCtx;
+    @Mock INetworkManagementService mNMService;
+    @Mock MockableSystemProperties mSystemProperties;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+        mContentResolver = new MockContentResolver();
+        mContentResolver.addProvider(Settings.AUTHORITY,
+                new FakeSettingsProvider());
+        when(mCtx.getContentResolver()).thenReturn(mContentResolver);
+        mDnsManager = new DnsManager(mCtx, mNMService, mSystemProperties);
+
+        // Clear the private DNS settings
+        Settings.Global.putString(mContentResolver,
+                Settings.Global.PRIVATE_DNS_MODE, "");
+        Settings.Global.putString(mContentResolver,
+                Settings.Global.PRIVATE_DNS_SPECIFIER, "");
+    }
+
+    @Test
+    public void testTrackedValidationUpdates() throws Exception {
+        mDnsManager.updatePrivateDns(new Network(TEST_NETID),
+                mDnsManager.getPrivateDnsConfig());
+        mDnsManager.updatePrivateDns(new Network(TEST_NETID_ALTERNATE),
+                mDnsManager.getPrivateDnsConfig());
+        LinkProperties lp = new LinkProperties();
+        lp.addDnsServer(InetAddress.getByName("3.3.3.3"));
+        lp.addDnsServer(InetAddress.getByName("4.4.4.4"));
+
+        // Send a validation event that is tracked on the alternate netId
+        mDnsManager.setDnsConfigurationForNetwork(TEST_NETID, lp, IS_DEFAULT);
+        mDnsManager.setDnsConfigurationForNetwork(TEST_NETID_ALTERNATE, lp, NOT_DEFAULT);
+        mDnsManager.updatePrivateDnsValidation(
+                new DnsManager.PrivateDnsValidationUpdate(TEST_NETID_ALTERNATE,
+                InetAddress.parseNumericAddress("4.4.4.4"), "", true));
+        LinkProperties fixedLp = new LinkProperties(lp);
+        mDnsManager.updatePrivateDnsStatus(TEST_NETID, fixedLp);
+        assertFalse(fixedLp.isPrivateDnsActive());
+        assertNull(fixedLp.getPrivateDnsServerName());
+        fixedLp = new LinkProperties(lp);
+        mDnsManager.updatePrivateDnsStatus(TEST_NETID_ALTERNATE, fixedLp);
+        assertTrue(fixedLp.isPrivateDnsActive());
+        assertNull(fixedLp.getPrivateDnsServerName());
+
+        // Switch to strict mode
+        Settings.Global.putString(mContentResolver,
+                Settings.Global.PRIVATE_DNS_MODE,
+                PRIVATE_DNS_MODE_PROVIDER_HOSTNAME);
+        Settings.Global.putString(mContentResolver,
+                Settings.Global.PRIVATE_DNS_SPECIFIER, "strictmode.com");
+        mDnsManager.updatePrivateDns(new Network(TEST_NETID),
+                mDnsManager.getPrivateDnsConfig());
+        mDnsManager.setDnsConfigurationForNetwork(TEST_NETID, lp, IS_DEFAULT);
+        fixedLp = new LinkProperties(lp);
+        mDnsManager.updatePrivateDnsStatus(TEST_NETID, fixedLp);
+        assertTrue(fixedLp.isPrivateDnsActive());
+        assertEquals("strictmode.com", fixedLp.getPrivateDnsServerName());
+        fixedLp = new LinkProperties(lp);
+    }
+
+    @Test
+    public void testIgnoreUntrackedValidationUpdates() throws Exception {
+        // The PrivateDnsConfig map is empty, so no validation events will
+        // be tracked.
+        LinkProperties lp = new LinkProperties();
+        lp.addDnsServer(InetAddress.getByName("3.3.3.3"));
+        mDnsManager.setDnsConfigurationForNetwork(TEST_NETID, lp, IS_DEFAULT);
+        mDnsManager.updatePrivateDnsValidation(
+                new DnsManager.PrivateDnsValidationUpdate(TEST_NETID,
+                InetAddress.parseNumericAddress("3.3.3.3"), "", true));
+        mDnsManager.updatePrivateDnsStatus(TEST_NETID, lp);
+        assertFalse(lp.isPrivateDnsActive());
+        assertNull(lp.getPrivateDnsServerName());
+
+        // Validation event has untracked netId
+        mDnsManager.updatePrivateDns(new Network(TEST_NETID),
+                mDnsManager.getPrivateDnsConfig());
+        mDnsManager.setDnsConfigurationForNetwork(TEST_NETID, lp, IS_DEFAULT);
+        mDnsManager.updatePrivateDnsValidation(
+                new DnsManager.PrivateDnsValidationUpdate(TEST_NETID_UNTRACKED,
+                InetAddress.parseNumericAddress("3.3.3.3"), "", true));
+        mDnsManager.updatePrivateDnsStatus(TEST_NETID, lp);
+        assertFalse(lp.isPrivateDnsActive());
+        assertNull(lp.getPrivateDnsServerName());
+
+        // Validation event has untracked ipAddress
+        mDnsManager.updatePrivateDnsValidation(
+                new DnsManager.PrivateDnsValidationUpdate(TEST_NETID,
+                InetAddress.parseNumericAddress("4.4.4.4"), "", true));
+        mDnsManager.updatePrivateDnsStatus(TEST_NETID, lp);
+        assertFalse(lp.isPrivateDnsActive());
+        assertNull(lp.getPrivateDnsServerName());
+
+        // Validation event has untracked hostname
+        mDnsManager.updatePrivateDnsValidation(
+                new DnsManager.PrivateDnsValidationUpdate(TEST_NETID,
+                InetAddress.parseNumericAddress("3.3.3.3"), "hostname",
+                true));
+        mDnsManager.updatePrivateDnsStatus(TEST_NETID, lp);
+        assertFalse(lp.isPrivateDnsActive());
+        assertNull(lp.getPrivateDnsServerName());
+
+        // Validation event failed
+        mDnsManager.updatePrivateDnsValidation(
+                new DnsManager.PrivateDnsValidationUpdate(TEST_NETID,
+                InetAddress.parseNumericAddress("3.3.3.3"), "", false));
+        mDnsManager.updatePrivateDnsStatus(TEST_NETID, lp);
+        assertFalse(lp.isPrivateDnsActive());
+        assertNull(lp.getPrivateDnsServerName());
+
+        // Network removed
+        mDnsManager.removeNetwork(new Network(TEST_NETID));
+        mDnsManager.updatePrivateDnsValidation(
+                new DnsManager.PrivateDnsValidationUpdate(TEST_NETID,
+                InetAddress.parseNumericAddress("3.3.3.3"), "", true));
+        mDnsManager.updatePrivateDnsStatus(TEST_NETID, lp);
+        assertFalse(lp.isPrivateDnsActive());
+        assertNull(lp.getPrivateDnsServerName());
+
+        // Turn private DNS mode off
+        Settings.Global.putString(mContentResolver,
+                Settings.Global.PRIVATE_DNS_MODE, PRIVATE_DNS_MODE_OFF);
+        mDnsManager.updatePrivateDns(new Network(TEST_NETID),
+                mDnsManager.getPrivateDnsConfig());
+        mDnsManager.setDnsConfigurationForNetwork(TEST_NETID, lp, IS_DEFAULT);
+        mDnsManager.updatePrivateDnsValidation(
+                new DnsManager.PrivateDnsValidationUpdate(TEST_NETID,
+                InetAddress.parseNumericAddress("3.3.3.3"), "", true));
+        mDnsManager.updatePrivateDnsStatus(TEST_NETID, lp);
+        assertFalse(lp.isPrivateDnsActive());
+        assertNull(lp.getPrivateDnsServerName());
+    }
+}