From 3c766ebc4d59c47a0de02afc6596e4eefdb86f5d Mon Sep 17 00:00:00 2001
From: Lorenzo Colitti <lorenzo@google.com>
Date: Thu, 31 Jan 2019 13:08:24 +0900
Subject: [PATCH] Allow use of bindProcessToNetwork only to change private DNS
 bypass.

Currently it is not possible to change private DNS bypass by
doing:

  setProcessDefaultNetwork(network.getPrivateDnsBypassingCopy());
  setProcessDefaultNetwork(network);

because the code will ignore the change. Fix this by ensuring
that we always call bindProcessToNetwork (which does not have
side effects) and then only performing the expensive operations
(flushing DNS cache, upating socket pools) if the netId changed.

Bug: 112869080
Test: None
Change-Id: I5e8999cb11d8b8c1e9eb583fa8b3932f212accff
---
 core/java/android/net/ConnectivityManager.java | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/core/java/android/net/ConnectivityManager.java b/core/java/android/net/ConnectivityManager.java
index 41a32a1df9..160157771b 100644
--- a/core/java/android/net/ConnectivityManager.java
+++ b/core/java/android/net/ConnectivityManager.java
@@ -3970,13 +3970,17 @@ public class ConnectivityManager {
     @Deprecated
     public static boolean setProcessDefaultNetwork(@Nullable Network network) {
         int netId = (network == null) ? NETID_UNSET : network.netId;
-        if (netId == NetworkUtils.getBoundNetworkForProcess()) {
-            return true;
-        }
+        boolean isSameNetId = (netId == NetworkUtils.getBoundNetworkForProcess());
+
         if (netId != NETID_UNSET) {
             netId = network.getNetIdForResolv();
         }
-        if (NetworkUtils.bindProcessToNetwork(netId)) {
+
+        if (!NetworkUtils.bindProcessToNetwork(netId)) {
+            return false;
+        }
+
+        if (!isSameNetId) {
             // Set HTTP proxy system properties to match network.
             // TODO: Deprecate this static method and replace it with a non-static version.
             try {
@@ -3990,10 +3994,9 @@ public class ConnectivityManager {
             // Must flush socket pool as idle sockets will be bound to previous network and may
             // cause subsequent fetches to be performed on old network.
             NetworkEventDispatcher.getInstance().onNetworkConfigurationChanged();
-            return true;
-        } else {
-            return false;
         }
+
+        return true;
     }
 
     /**