From 72a42151edcf6d60da129d8baa264281fbeda137 Mon Sep 17 00:00:00 2001
From: "Mark D. Roth" <roth@google.com>
Date: Fri, 1 May 2020 07:23:01 -0700
Subject: [PATCH] xds: Check RDS ConfigSource in LDS response.

---
 .../ext/filters/client_channel/xds/xds_api.cc | 14 +++++-
 test/cpp/end2end/xds_end2end_test.cc          | 46 ++++++++++++++++++-
 2 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/src/core/ext/filters/client_channel/xds/xds_api.cc b/src/core/ext/filters/client_channel/xds/xds_api.cc
index 60ca930e060..f124052ce84 100644
--- a/src/core/ext/filters/client_channel/xds/xds_api.cc
+++ b/src/core/ext/filters/client_channel/xds/xds_api.cc
@@ -1174,10 +1174,22 @@ grpc_error* LdsResponseParse(XdsClient* client, TraceFlag* tracer,
       return GRPC_ERROR_CREATE_FROM_STATIC_STRING(
           "HttpConnectionManager neither has inlined route_config nor RDS.");
     }
-    // Get the route_config_name.
     const envoy_config_filter_network_http_connection_manager_v2_Rds* rds =
         envoy_config_filter_network_http_connection_manager_v2_HttpConnectionManager_rds(
             http_connection_manager);
+    // Check that the ConfigSource specifies ADS.
+    const envoy_api_v2_core_ConfigSource* config_source =
+        envoy_config_filter_network_http_connection_manager_v2_Rds_config_source(
+            rds);
+    if (config_source == nullptr) {
+      return GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "HttpConnectionManager missing config_source for RDS.");
+    }
+    if (!envoy_api_v2_core_ConfigSource_has_ads(config_source)) {
+      return GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "HttpConnectionManager ConfigSource for RDS does not specify ADS.");
+    }
+    // Get the route_config_name.
     const upb_strview route_config_name =
         envoy_config_filter_network_http_connection_manager_v2_Rds_route_config_name(
             rds);
diff --git a/test/cpp/end2end/xds_end2end_test.cc b/test/cpp/end2end/xds_end2end_test.cc
index 5fb6a62b19d..7d70feadbad 100644
--- a/test/cpp/end2end/xds_end2end_test.cc
+++ b/test/cpp/end2end/xds_end2end_test.cc
@@ -713,8 +713,9 @@ class AdsServiceImpl : public AggregatedDiscoveryService::Service,
   void SetLdsToUseDynamicRds() {
     auto listener = default_listener_;
     HttpConnectionManager http_connection_manager;
-    http_connection_manager.mutable_rds()->set_route_config_name(
-        kDefaultResourceName);
+    auto* rds = http_connection_manager.mutable_rds();
+    rds->set_route_config_name(kDefaultResourceName);
+    rds->mutable_config_source()->mutable_ads();
     listener.mutable_api_listener()->mutable_api_listener()->PackFrom(
         http_connection_manager);
     SetLdsResource(listener, kDefaultResourceName);
@@ -2191,6 +2192,47 @@ TEST_P(LdsTest, WrongRouteSpecifier) {
             "HttpConnectionManager neither has inlined route_config nor RDS.");
 }
 
+// Tests that LDS client should send a NACK if the rds message in the
+// http_connection_manager is missing the config_source field.
+TEST_P(LdsTest, RdsMissingConfigSource) {
+  auto listener = balancers_[0]->ads_service()->default_listener();
+  HttpConnectionManager http_connection_manager;
+  http_connection_manager.mutable_rds()->set_route_config_name(
+      kDefaultResourceName);
+  listener.mutable_api_listener()->mutable_api_listener()->PackFrom(
+      http_connection_manager);
+  balancers_[0]->ads_service()->SetLdsResource(listener, kDefaultResourceName);
+  SetNextResolution({});
+  SetNextResolutionForLbChannelAllBalancers();
+  CheckRpcSendFailure();
+  const auto& response_state =
+      balancers_[0]->ads_service()->lds_response_state();
+  EXPECT_EQ(response_state.state, AdsServiceImpl::ResponseState::NACKED);
+  EXPECT_EQ(response_state.error_message,
+            "HttpConnectionManager missing config_source for RDS.");
+}
+
+// Tests that LDS client should send a NACK if the rds message in the
+// http_connection_manager has a config_source field that does not specify ADS.
+TEST_P(LdsTest, RdsConfigSourceDoesNotSpecifyAds) {
+  auto listener = balancers_[0]->ads_service()->default_listener();
+  HttpConnectionManager http_connection_manager;
+  auto* rds = http_connection_manager.mutable_rds();
+  rds->set_route_config_name(kDefaultResourceName);
+  rds->mutable_config_source()->mutable_self();
+  listener.mutable_api_listener()->mutable_api_listener()->PackFrom(
+      http_connection_manager);
+  balancers_[0]->ads_service()->SetLdsResource(listener, kDefaultResourceName);
+  SetNextResolution({});
+  SetNextResolutionForLbChannelAllBalancers();
+  CheckRpcSendFailure();
+  const auto& response_state =
+      balancers_[0]->ads_service()->lds_response_state();
+  EXPECT_EQ(response_state.state, AdsServiceImpl::ResponseState::NACKED);
+  EXPECT_EQ(response_state.error_message,
+            "HttpConnectionManager ConfigSource for RDS does not specify ADS.");
+}
+
 using LdsRdsTest = BasicTest;
 
 // Tests that LDS client should send an ACK upon correct LDS response (with