XdsNameResolver and XdsServerWrapper don't check listener type

[ejona86]

Our resource parsing supports two listener types (I'm not confident enough validation is happening here):

grpc-java/xds/src/main/java/io/grpc/xds/XdsListenerResource.java

Lines 110 to 114 in 210f9c0

	if (listener.hasApiListener()) {
	return processClientSideListener(listener, args);
	} else {
	return processServerSideListener(listener, args);
	}

But XdsNameResolver and XdsServerWrapper don't check that they got the right type. No changes were made to XdsNameResolver when non-API listener type was allowed, so I doubt the logic exists but I'm just not seeing it.

I also don't see XdsServerWrapper call address(), so it appears it is not follow gRFC A36.

The XdsServer must be "not serving" if the address does not match.

[ejona86]

Looks like the client receiving a socket listener will throw a NullPointerException, because httpConnectionManager() is null and instead listener() is set:

grpc-java/xds/src/main/java/io/grpc/xds/XdsNameResolver.java

Lines 661 to 663 in e8ff6da

	HttpConnectionManager httpConnectionManager = update.httpConnectionManager();
	List<VirtualHost> virtualHosts = httpConnectionManager.virtualHosts();
	String rdsName = httpConnectionManager.rdsName();