xds: update isolatedResourceUpdates test to directly send unsolicited ADS response

Add sendDiscoveryResponse to XdsTestControlPlaneService and update
isolatedResourceUpdates test in XdsClientFederationTest to directly
send an unsolicited cross-authority ADS response on the wire, properly
exercising the control plane isolation check in XdsClientImpl.

TAG=agy
CONV=e27e4459-da3e-4c14-b2a1-2055f0b9b5d1

Author: kannanjgithub

xds/src/test/java/io/grpc/xds/XdsClientFederationTest.java

@@ -26,7 +26,9 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.protobuf.Any;
 import io.envoyproxy.envoy.config.listener.v3.Listener;
+import io.envoyproxy.envoy.service.discovery.v3.DiscoveryResponse;
 import io.grpc.MetricRecorder;
 import io.grpc.Status;
 import io.grpc.StatusOr;
@@ -149,22 +151,34 @@ public void isolatedResourceDeletions() {
    */
   @Test
   public void isolatedResourceUpdates() {
-    Listener serverListener = ControlPlaneRule.buildServerListener();
-    Listener clientListener1 = ControlPlaneRule.buildClientListener("test-server");
-    Listener clientListener2 = ControlPlaneRule.buildClientListener(
-        "xdstp://server-one/envoy.config.listener.v3.Listener/test-server");
-    // trafficdirector (top-level server) erroneously sends a listener owned by server-one.
-    trafficdirector.getService().setXdsConfig(XdsTestControlPlaneService.ADS_TYPE_URL_LDS,
-        ImmutableMap.of(
-            serverListener.getName(), serverListener,
-            clientListener1.getName(), clientListener1,
-            clientListener2.getName(), clientListener2));
+    trafficdirector.setLdsConfig(ControlPlaneRule.buildServerListener(),
+        ControlPlaneRule.buildClientListener("test-server"));
 
     xdsClient.watchXdsResource(XdsListenerResource.getInstance(), "test-server", mockWatcher);
     xdsClient.watchXdsResource(XdsListenerResource.getInstance(),
         "xdstp://server-one/envoy.config.listener.v3.Listener/test-server", mockDirectPathWatcher);
 
     verify(mockWatcher, timeout(10000)).onResourceChanged(any());
+
+    // trafficdirector (top-level server) erroneously sends a response containing both an update
+    // for test-server and a listener owned by server-one.
+    Listener alienListener = ControlPlaneRule.buildClientListener(
+        "xdstp://server-one/envoy.config.listener.v3.Listener/test-server");
+    Listener updatedClientListener = ControlPlaneRule.buildClientListener("test-server",
+        "new-route-config.googleapis.com");
+    DiscoveryResponse rogueResponse = DiscoveryResponse.newBuilder()
+        .setTypeUrl(XdsTestControlPlaneService.ADS_TYPE_URL_LDS)
+        .setVersionInfo("rogue-version-1")
+        .setNonce("rogue-nonce-1")
+        .addResources(Any.pack(updatedClientListener))
+        .addResources(Any.pack(alienListener))
+        .build();
+    trafficdirector.getService().sendDiscoveryResponse(rogueResponse);
+
+    // Confirm that trafficdirector's second response was processed by waiting for mockWatcher
+    // to receive the updated test-server config.
+    verify(mockWatcher, timeout(10000).times(2)).onResourceChanged(any());
+
     // mockDirectPathWatcher should not receive the update sent by trafficdirector.
     verify(mockDirectPathWatcher, never()).onResourceChanged(any());
 

xds/src/test/java/io/grpc/xds/XdsTestControlPlaneService.java

@@ -119,6 +119,21 @@ public void run() {
     });
   }
 
+  /**
+   * Directly sends the given DiscoveryResponse to all active subscribers of the response's type.
+   */
+  public void sendDiscoveryResponse(DiscoveryResponse response) {
+    syncContext.execute(new Runnable() {
+      @Override
+      public void run() {
+        for (StreamObserver<DiscoveryResponse> observer :
+            subscribers.get(response.getTypeUrl()).keySet()) {
+          observer.onNext(response);
+        }
+      }
+    });
+  }
+
   ImmutableMap<String, Message> getCurrentConfig(String type) {
     HashMap<String, Message> hashMap = xdsResources.get(type);
     return (hashMap != null) ? ImmutableMap.copyOf(hashMap) : ImmutableMap.of();