Restore the Private DNS settings to default mode upon network resets.

Bug: 134918038
Test: atest FrameworksNetTests NetworkStackTests
Test: manual test
      configure private dns settings (e.g. dns.google) -> connect Wi-Fi
      -> click "Reset Wi-Fi, mobile & Bluetooth" -> verify private dns
      settings is automatic -> connect Wi-Fi -> verify Internet
      connection.

Change-Id: I13562af622d7b584d6219f74534219b7868275f9

1 files changed, 7 insertions, 0 deletions

diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index 5027a124e075..de9d8f5caa8d 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -20,6 +20,7 @@ import static android.Manifest.permission.RECEIVE_DATA_ACTIVITY_CHANGE;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
 import static android.net.ConnectivityManager.NETID_UNSET;
+import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_OPPORTUNISTIC;
 import static android.net.ConnectivityManager.TYPE_ETHERNET;
 import static android.net.ConnectivityManager.TYPE_NONE;
 import static android.net.ConnectivityManager.TYPE_VPN;
@@ -6952,6 +6953,12 @@ public class ConnectivityService extends IConnectivityManager.Stub
             }
         }
 
+        // restore private DNS settings to default mode (opportunistic)
+        if (!mUserManager.hasUserRestriction(UserManager.DISALLOW_CONFIG_PRIVATE_DNS)) {
+            Settings.Global.putString(mContext.getContentResolver(),
+                    Settings.Global.PRIVATE_DNS_MODE, PRIVATE_DNS_MODE_OPPORTUNISTIC);
+        }
+
         Settings.Global.putString(mContext.getContentResolver(),
                 Settings.Global.NETWORK_AVOID_BAD_WIFI, null);
     }