From 78f8585339f149ea17db3d61cc3358dc9affed74 Mon Sep 17 00:00:00 2001
From: Lorenzo Colitti <lorenzo@google.com>
Date: Tue, 5 Jun 2018 15:44:23 +0900
Subject: [PATCH] Wait a few seconds for IPv6 connectivity to appear.

Currently, DnsTest immediately executes a DNS lookup as soon as
it starts. If the device has just connected to a network - as it
might if the test framework has just enabled wifi - and IPv6
connectivity is not yet available, the test will fail with little
proof that the network doesn't have IPv6.

Fix this by waiting for IPv6 connectivity and by adding the
active LinkProperties to the failure message.

Bug: 109670546
Test: DnsTest passes on dual-stack network
Test: DnsTest fails on IPv4-only network
Change-Id: I88b8d001f08fe41af666bccf8094c67729dda9c2
---
 .../cts/net/src/android/net/cts/DnsTest.java  | 54 ++++++++++++++++---
 1 file changed, 46 insertions(+), 8 deletions(-)

diff --git a/tests/cts/net/src/android/net/cts/DnsTest.java b/tests/cts/net/src/android/net/cts/DnsTest.java
index 8575c338dd..84231c25a8 100644
--- a/tests/cts/net/src/android/net/cts/DnsTest.java
+++ b/tests/cts/net/src/android/net/cts/DnsTest.java
@@ -19,6 +19,9 @@ package android.net.cts;
 import android.content.Context;
 import android.content.pm.PackageManager;
 import android.net.ConnectivityManager;
+import android.net.ConnectivityManager.NetworkCallback;
+import android.net.LinkProperties;
+import android.net.Network;
 import android.net.NetworkInfo;
 import android.os.SystemClock;
 import android.test.AndroidTestCase;
@@ -29,6 +32,8 @@ import java.net.Inet6Address;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
 
 public class DnsTest extends AndroidTestCase {
 
@@ -40,6 +45,12 @@ public class DnsTest extends AndroidTestCase {
     private static final String TAG = "DnsTest";
     private static final String PROXY_NETWORK_TYPE = "PROXY";
 
+    private ConnectivityManager mCm;
+
+    public void setUp() {
+        mCm = getContext().getSystemService(ConnectivityManager.class);
+    }
+
     /**
      * @return true on success
      */
@@ -57,7 +68,9 @@ public class DnsTest extends AndroidTestCase {
      * Perf - measure size of first and second tier caches and their effect
      * Assert requires network permission
      */
-    public void testDnsWorks() {
+    public void testDnsWorks() throws Exception {
+        ensureIpv6Connectivity();
+
         InetAddress addrs[] = {};
         try {
             addrs = InetAddress.getAllByName("www.google.com");
@@ -88,11 +101,14 @@ public class DnsTest extends AndroidTestCase {
         try {
             addrs = InetAddress.getAllByName("ipv6.google.com");
         } catch (UnknownHostException e) {}
-        assertTrue("[RERUN] DNS could not resolve ipv6.google.com, check the network supports IPv6",
-                addrs.length != 0);
+        String msg =
+            "[RERUN] DNS could not resolve ipv6.google.com, check the network supports IPv6. lp=" +
+            mCm.getActiveLinkProperties();
+        assertTrue(msg, addrs.length != 0);
         for (InetAddress addr : addrs) {
-            assertFalse ("[RERUN] ipv6.google.com returned IPv4 address: " + addr.getHostAddress() +
-                    ", check your network's DNS server", addr instanceof Inet4Address);
+            msg = "[RERUN] ipv6.google.com returned IPv4 address: " + addr.getHostAddress() +
+                    ", check your network's DNS server. lp=" + mCm.getActiveLinkProperties();
+            assertFalse (msg, addr instanceof Inet4Address);
             foundV6 |= (addr instanceof Inet6Address);
             if (DBG) Log.e(TAG, "ipv6.google.com gave " + addr.toString());
         }
@@ -256,13 +272,35 @@ public class DnsTest extends AndroidTestCase {
     }
 
     private boolean activeNetworkInfoIsProxy() {
-        ConnectivityManager cm = (ConnectivityManager)
-                getContext().getSystemService(Context.CONNECTIVITY_SERVICE);
-        NetworkInfo info = cm.getActiveNetworkInfo();
+        NetworkInfo info = mCm.getActiveNetworkInfo();
         if (PROXY_NETWORK_TYPE.equals(info.getTypeName())) {
             return true;
         }
 
         return false;
     }
+
+    private void ensureIpv6Connectivity() throws InterruptedException {
+        CountDownLatch latch = new CountDownLatch(1);
+        final int TIMEOUT_MS = 5_000;
+
+        final NetworkCallback callback = new NetworkCallback() {
+            @Override
+            public void onLinkPropertiesChanged(Network network, LinkProperties lp) {
+                if (lp.hasGlobalIPv6Address()) {
+                    latch.countDown();
+                }
+            }
+        };
+        mCm.registerDefaultNetworkCallback(callback);
+
+        String msg = "Default network did not provide IPv6 connectivity after " + TIMEOUT_MS
+                + "ms. Please connect to an IPv6-capable network. lp="
+                + mCm.getActiveLinkProperties();
+        try {
+            assertTrue(msg, latch.await(TIMEOUT_MS, TimeUnit.MILLISECONDS));
+        } finally {
+            mCm.unregisterNetworkCallback(callback);
+        }
+    }
 }