Make DNS cache lifecycle management explicit

1. ConnectivityService calls netd binder to create/destroy network directly.
2. Call dnsresolver binder to create/destroy cache after create/destroy network.
3. Remove unused network create/destroy methods in NetworkManagementService.

Bug: 129453995
Test: atest FrameworksNetTests

Merged-In: I388e208143c38b89bcbb0589de393250024d59aa
(cherry picked from commit 204ca13e63f063f044ac4ad3b96f08b473fe59df)

Change-Id: I4d3dfd9305b60a724aa2dc38448948d8e710c932

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

@@ -3071,11 +3071,7 @@ public class ConnectivityService extends IConnectivityManager.Stub
             // fallback network the default or requested a new network from the
             // NetworkFactories, so network traffic isn't interrupted for an unnecessarily
             // long time.
-            try {
-                mNetd.networkDestroy(nai.network.netId);
-            } catch (RemoteException | ServiceSpecificException e) {
-                loge("Exception destroying network: " + e);
-            }
+            destroyNativeNetwork(nai);
             mDnsManager.removeNetwork(nai.network);
         }
         synchronized (mNetworkForNetId) {
@@ -3083,6 +3079,35 @@ public class ConnectivityService extends IConnectivityManager.Stub
         }
     }
 
+    private boolean createNativeNetwork(@NonNull NetworkAgentInfo networkAgent) {
+        try {
+            // This should never fail.  Specifying an already in use NetID will cause failure.
+            if (networkAgent.isVPN()) {
+                mNetd.networkCreateVpn(networkAgent.network.netId,
+                        (networkAgent.networkMisc == null
+                                || !networkAgent.networkMisc.allowBypass));
+            } else {
+                mNetd.networkCreatePhysical(networkAgent.network.netId,
+                        getNetworkPermission(networkAgent.networkCapabilities));
+            }
+            mDnsResolver.createNetworkCache(networkAgent.network.netId);
+            return true;
+        } catch (RemoteException | ServiceSpecificException e) {
+            loge("Error creating network " + networkAgent.network.netId + ": "
+                    + e.getMessage());
+            return false;
+        }
+    }
+
+    private void destroyNativeNetwork(@NonNull NetworkAgentInfo networkAgent) {
+        try {
+            mNetd.networkDestroy(networkAgent.network.netId);
+            mDnsResolver.destroyNetworkCache(networkAgent.network.netId);
+        } catch (RemoteException | ServiceSpecificException e) {
+            loge("Exception destroying network: " + e);
+        }
+    }
+
     // If this method proves to be too slow then we can maintain a separate
     // pendingIntent => NetworkRequestInfo map.
     // This method assumes that every non-null PendingIntent maps to exactly 1 NetworkRequestInfo.
@@ -6476,21 +6501,7 @@ public class ConnectivityService extends IConnectivityManager.Stub
             // A network that has just connected has zero requests and is thus a foreground network.
             networkAgent.networkCapabilities.addCapability(NET_CAPABILITY_FOREGROUND);
 
-            try {
-                // This should never fail.  Specifying an already in use NetID will cause failure.
-                if (networkAgent.isVPN()) {
-                    mNMS.createVirtualNetwork(networkAgent.network.netId,
-                            (networkAgent.networkMisc == null ||
-                                !networkAgent.networkMisc.allowBypass));
-                } else {
-                    mNMS.createPhysicalNetwork(networkAgent.network.netId,
-                            getNetworkPermission(networkAgent.networkCapabilities));
-                }
-            } catch (Exception e) {
-                loge("Error creating network " + networkAgent.network.netId + ": "
-                        + e.getMessage());
-                return;
-            }
+            if (!createNativeNetwork(networkAgent)) return;
             networkAgent.created = true;
         }
 

services/core/java/com/android/server/connectivity/DnsManager.java

@@ -263,12 +263,6 @@ public class DnsManager {
     }
 
     public void removeNetwork(Network network) {
-        try {
-            mDnsResolver.clearResolverConfiguration(network.netId);
-        } catch (RemoteException | ServiceSpecificException e) {
-            Slog.e(TAG, "Error clearing DNS configuration: " + e);
-            return;
-        }
         mPrivateDnsMap.remove(network.netId);
         mPrivateDnsValidationMap.remove(network.netId);
     }

tests/net/java/com/android/server/ConnectivityServiceTest.java

@@ -4894,7 +4894,10 @@ public class ConnectivityServiceTest {
         mCellNetworkAgent.sendLinkProperties(cellLp);
         mCellNetworkAgent.connect(false);
         waitForIdle();
-        // CS tells netd about the empty DNS config for this network.
+
+        verify(mMockDnsResolver, times(1)).createNetworkCache(
+                eq(mCellNetworkAgent.getNetwork().netId));
+        // CS tells dnsresolver about the empty DNS config for this network.
         verify(mMockDnsResolver, atLeastOnce()).setResolverConfiguration(any());
         reset(mMockDnsResolver);
 
@@ -4978,6 +4981,8 @@ public class ConnectivityServiceTest {
         mCellNetworkAgent.sendLinkProperties(cellLp);
         mCellNetworkAgent.connect(false);
         waitForIdle();
+        verify(mMockDnsResolver, times(1)).createNetworkCache(
+                eq(mCellNetworkAgent.getNetwork().netId));
         verify(mMockDnsResolver, atLeastOnce()).setResolverConfiguration(
                 mResolverParamsParcelCaptor.capture());
         ResolverParamsParcel resolvrParams = mResolverParamsParcelCaptor.getValue();
@@ -5851,12 +5856,17 @@ public class ConnectivityServiceTest {
         cellLp.addRoute(new RouteInfo(myIpv6, null, MOBILE_IFNAME));
         reset(mNetworkManagementService);
         reset(mMockDnsResolver);
+        reset(mMockNetd);
         when(mNetworkManagementService.getInterfaceConfig(CLAT_PREFIX + MOBILE_IFNAME))
                 .thenReturn(getClatInterfaceConfig(myIpv4));
 
         // Connect with ipv6 link properties. Expect prefix discovery to be started.
         mCellNetworkAgent.sendLinkProperties(cellLp);
         mCellNetworkAgent.connect(true);
+
+        verify(mMockNetd, times(1)).networkCreatePhysical(eq(cellNetId), anyInt());
+        verify(mMockDnsResolver, times(1)).createNetworkCache(eq(cellNetId));
+
         networkCallback.expectAvailableThenValidatedCallbacks(mCellNetworkAgent);
         verify(mMockDnsResolver, times(1)).startPrefix64Discovery(cellNetId);
 
@@ -6048,7 +6058,7 @@ public class ConnectivityServiceTest {
         verify(mNetworkManagementService, times(0)).removeIdleTimer(eq(MOBILE_IFNAME));
         verify(mMockNetd, times(1)).networkDestroy(eq(mCellNetworkAgent.getNetwork().netId));
         verify(mMockDnsResolver, times(1))
-                .clearResolverConfiguration(eq(mCellNetworkAgent.getNetwork().netId));
+                .destroyNetworkCache(eq(mCellNetworkAgent.getNetwork().netId));
 
         // Disconnect wifi
         ConditionVariable cv = waitForConnectivityBroadcasts(1);