From 2790990866b2171b3762ba499657824d8a314012 Mon Sep 17 00:00:00 2001
From: Sudheer Shanka <sudheersai@google.com>
Date: Mon, 11 Jul 2022 18:07:47 +0000
Subject: [PATCH] Clear DNS cache after every network access.

If the app tries to make a network connection in the
foreground immediately after trying to do the same when
it's network access was blocked, it could receive a
UnknownHostException due to the cached DNS entry.
So, clear the dns cache after every network access for
now until we have a fix on the platform side.

Bug: 237549250
Bug: 238064333
Bug: 237556596
Bug: 238962235
Bug: 238833668
Bug: 239262832
Test: atest ./tests/cts/hostside/src/com/android/cts/net/HostsideRestrictBackgroundNetworkTests.java
Ignore-AOSP-First: Will be cherrypicked to aosp later
Change-Id: Ic603b1bd9da24ee3724054c4a91794ee569e97f6
---
 tests/cts/hostside/app2/Android.bp                          | 2 +-
 .../android/cts/net/hostside/app2/MyBroadcastReceiver.java  | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/tests/cts/hostside/app2/Android.bp b/tests/cts/hostside/app2/Android.bp
index edfaf9fdd3..db92f5c15a 100644
--- a/tests/cts/hostside/app2/Android.bp
+++ b/tests/cts/hostside/app2/Android.bp
@@ -21,7 +21,7 @@ package {
 android_test_helper_app {
     name: "CtsHostsideNetworkTestsApp2",
     defaults: ["cts_support_defaults"],
-    sdk_version: "test_current",
+    platform_apis: true,
     static_libs: [
         "androidx.annotation_annotation",
         "CtsHostsideNetworkTestsAidl",
diff --git a/tests/cts/hostside/app2/src/com/android/cts/net/hostside/app2/MyBroadcastReceiver.java b/tests/cts/hostside/app2/src/com/android/cts/net/hostside/app2/MyBroadcastReceiver.java
index 771b404705..825f2c9019 100644
--- a/tests/cts/hostside/app2/src/com/android/cts/net/hostside/app2/MyBroadcastReceiver.java
+++ b/tests/cts/hostside/app2/src/com/android/cts/net/hostside/app2/MyBroadcastReceiver.java
@@ -48,6 +48,7 @@ import android.util.Log;
 import android.widget.Toast;
 
 import java.net.HttpURLConnection;
+import java.net.InetAddress;
 import java.net.URL;
 
 /**
@@ -182,6 +183,11 @@ public class MyBroadcastReceiver extends BroadcastReceiver {
             checkStatus = false;
             checkDetails = "Exception getting " + address + ": " + e;
         }
+        // If the app tries to make a network connection in the foreground immediately after
+        // trying to do the same when it's network access was blocked, it could receive a
+        // UnknownHostException due to the cached DNS entry. So, clear the dns cache after
+        // every network access for now until we have a fix on the platform side.
+        InetAddress.clearDnsCache();
         Log.d(TAG, checkDetails);
         final String state, detailedState;
         if (networkInfo != null) {