commit 603df207b47cde91e685b6eb93121151f599a6a2
author Erik Kline <ek@google.com> Mon Sep 10 18:16:26 2018 +0900
committer Erik Kline <ek@google.com> Tue Sep 11 23:05:05 2018 +0900
tree 3565deb6c43d0e0953caf35a8f1411051cf6f126
parent 1737e82559e33e206d61b5542b165f701047d5ee

Address outstanding comments from aosp/713992

Test: as follows
    - built, flashed, booted
    - system/netd/tests/runtest.sh passes
    - connected to a DNS64 network and observed prefix discovery
      via "adb shell dumpsys netd"
Bug: 78545619
Change-Id: I7ae6bf258bb3f22795274026187ee8493875aace

server/ResolverController.cpp

diff --git a/server/ResolverController.cpp b/server/ResolverController.cpp
index 65e3d69..506eb8a 100644
--- a/server/ResolverController.cpp
+++ b/server/ResolverController.cpp
@@ -554,6 +554,11 @@
         // Operators may choose to use a longer TTL in order to reduce repeated
         // resolution (see also https://tools.ietf.org/html/rfc7050#section-5).
         if (allIPv6Only(servers)) {
+            // TODO: Keep any existing discovered prefix around for use while
+            // re-discovery is in progress. Otherwise, whenever DNS servers are
+            // pushed to netd there can be gaps where it would appear there was
+            // no prefix64 when in fact we had previously discovered one (and
+            // are highly likely to rediscover the same one).
             mDns64Configuration.startPrefixDiscovery(netId);
         } else {
             mDns64Configuration.stopPrefixDiscovery(netId);

server/dns/Dns64Configuration.cpp

diff --git a/server/dns/Dns64Configuration.cpp b/server/dns/Dns64Configuration.cpp
index aa6cc56..fed7ad2 100644
--- a/server/dns/Dns64Configuration.cpp
+++ b/server/dns/Dns64Configuration.cpp
@@ -174,7 +174,7 @@
     return true;
 }
 
-bool Dns64Configuration::mapContainsConfig(const Dns64Config& cfg) const REQUIRES(mMutex) {
+bool Dns64Configuration::isDiscoveryInProgress(const Dns64Config& cfg) const REQUIRES(mMutex) {
     const auto& iter = mDns64Configs.find(cfg.netId);
     if (iter == mDns64Configs.end()) return false;
 
@@ -184,12 +184,12 @@
 
 bool Dns64Configuration::shouldContinueDiscovery(const Dns64Config& cfg) {
     std::lock_guard guard(mMutex);
-    return mapContainsConfig(cfg);
+    return isDiscoveryInProgress(cfg);
 }
 
 void Dns64Configuration::recordDns64Config(const Dns64Config& cfg) {
     std::lock_guard guard(mMutex);
-    if (!mapContainsConfig(cfg)) return;
+    if (!isDiscoveryInProgress(cfg)) return;
 
     mDns64Configs.erase(cfg.netId);
     mDns64Configs.emplace(std::make_pair(cfg.netId, cfg));

server/dns/Dns64Configuration.h

diff --git a/server/dns/Dns64Configuration.h b/server/dns/Dns64Configuration.h
index ac9da3a..17f2561 100644
--- a/server/dns/Dns64Configuration.h
+++ b/server/dns/Dns64Configuration.h
@@ -82,7 +82,7 @@
     static bool doRfc7050PrefixDiscovery(const android_net_context& netcontext, Dns64Config* cfg);
 
     unsigned getNextId() REQUIRES(mMutex) { return mNextId++; }
-    bool mapContainsConfig(const Dns64Config& cfg) const REQUIRES(mMutex);
+    bool isDiscoveryInProgress(const Dns64Config& cfg) const REQUIRES(mMutex);
 
     bool shouldContinueDiscovery(const Dns64Config& cfg);
     void recordDns64Config(const Dns64Config& cfg);