commit 20068c2d12dbccb7a57fcfca9ec63460268f65d2
author Lorenzo Colitti <lorenzo@google.com> Fri Nov 28 20:07:46 2014 +0900
committer Lorenzo Colitti <lorenzo@google.com> Tue Dec 02 03:40:16 2014 +0900
tree 65a6fb37140249904f9997770b84860f003b71ff
parent 1d27e7d678b3d9ae03bf15ceb4979b133a92d693

Only use mDefaultDns if the network claims to offer Internet

Currently, if a network does not specify DNS servers, we default
it to using 8.8.8.8. This was done because the emulator did not
specify DNS servers. However, it causes queries to fail slowly,
instead of failing fast, on networks that do not have
connectivity to 8.8.8.8.

Bug: 18327075
Change-Id: I0df13ff4a17ee65e640be96695a3af31b020963a

services/core/java/com/android/server/ConnectivityService.java

diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index 8b3739d..9f86d9a 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -3593,8 +3593,14 @@
 //            updateMtu(lp, null);
 //        }
         updateTcpBufferSizes(networkAgent);
+
+        // TODO: deprecate and remove mDefaultDns when we can do so safely.
+        // For now, use it only when the network has Internet access. http://b/18327075
+        final boolean useDefaultDns = networkAgent.networkCapabilities.hasCapability(
+                NetworkCapabilities.NET_CAPABILITY_INTERNET);
         final boolean flushDns = updateRoutes(newLp, oldLp, netId);
-        updateDnses(newLp, oldLp, netId, flushDns);
+        updateDnses(newLp, oldLp, netId, flushDns, useDefaultDns);
+
         updateClat(newLp, oldLp, networkAgent);
         if (isDefaultNetwork(networkAgent)) handleApplyDefaultProxy(newLp.getHttpProxy());
         // TODO - move this check to cover the whole function
@@ -3688,10 +3694,11 @@
         }
         return !routeDiff.added.isEmpty() || !routeDiff.removed.isEmpty();
     }
-    private void updateDnses(LinkProperties newLp, LinkProperties oldLp, int netId, boolean flush) {
+    private void updateDnses(LinkProperties newLp, LinkProperties oldLp, int netId,
+                             boolean flush, boolean useDefaultDns) {
         if (oldLp == null || (newLp.isIdenticalDnses(oldLp) == false)) {
             Collection<InetAddress> dnses = newLp.getDnsServers();
-            if (dnses.size() == 0 && mDefaultDns != null) {
+            if (dnses.size() == 0 && mDefaultDns != null && useDefaultDns) {
                 dnses = new ArrayList();
                 dnses.add(mDefaultDns);
                 if (DBG) {