network: add ext proc config check for processing mode and grpc services (envoyproxy#39284)

Throw in this PR, but I think a better way is to change the interface of
`createFilterFactoryFromProtoTyped` to return `absl:status` to avoid
throw for network filters.

Commit Message:
Additional Description:
Risk Level: low
Testing:
Docs Changes:
Release Notes:
Platform Specific Features:

---------

Signed-off-by: Boteng Yao <[email protected]>

Author: botengyao

source/extensions/filters/network/ext_proc/config.cc

@@ -15,9 +15,34 @@ namespace Extensions {
 namespace NetworkFilters {
 namespace ExtProc {
 
+namespace {
+
+absl::Status verifyFilterConfig(
+    const envoy::extensions::filters::network::ext_proc::v3::NetworkExternalProcessor& config) {
+  if (!config.has_grpc_service()) {
+    return absl::InvalidArgumentError("A grpc_service must be configured");
+  }
+
+  if (config.processing_mode().process_read() ==
+          envoy::extensions::filters::network::ext_proc::v3::ProcessingMode::SKIP &&
+      config.processing_mode().process_write() ==
+          envoy::extensions::filters::network::ext_proc::v3::ProcessingMode::SKIP) {
+    return absl::InvalidArgumentError(
+        "both read and write paths are skipped, at least one must be enabled.");
+  }
+  return absl::OkStatus();
+}
+
+} // namespace
+
 Network::FilterFactoryCb NetworkExtProcConfigFactory::createFilterFactoryFromProtoTyped(
     const envoy::extensions::filters::network::ext_proc::v3::NetworkExternalProcessor& proto_config,
     Server::Configuration::FactoryContext& context) {
+  absl::Status result = verifyFilterConfig(proto_config);
+  if (!result.ok()) {
+    throw EnvoyException(std::string(result.message()));
+  }
+
   ConfigConstSharedPtr ext_proc_config = std::make_shared<const Config>(proto_config);
 
   return [ext_proc_config, &context](Network::FilterManager& filter_manager) -> void {

test/extensions/filters/network/ext_proc/config_test.cc

@@ -109,6 +109,47 @@ TEST(NetworkExtProcConfigTest, ConfigWithOptions) {
   cb(filter_manager);
 }
 
+// Test the config without a gRPC service.
+TEST(NetworkExtProcConfigFactoryTest, MissingGrpcService) {
+  envoy::extensions::filters::network::ext_proc::v3::NetworkExternalProcessor proto_config;
+
+  NiceMock<Server::Configuration::MockFactoryContext> context;
+  NetworkExtProcConfigFactory factory;
+
+  EXPECT_THROW_WITH_MESSAGE(auto cb = factory.createFilterFactoryFromProto(proto_config, context),
+                            EnvoyException, "A grpc_service must be configured");
+}
+
+// Test the config with both SKIP modes.
+TEST(NetworkExtProcConfigFactoryTest, BothModesSkipped) {
+  envoy::extensions::filters::network::ext_proc::v3::NetworkExternalProcessor proto_config;
+  proto_config.mutable_grpc_service()->mutable_envoy_grpc()->set_cluster_name("ext_proc_server");
+
+  auto* processing_mode = proto_config.mutable_processing_mode();
+  processing_mode->set_process_read(
+      envoy::extensions::filters::network::ext_proc::v3::ProcessingMode::SKIP);
+  processing_mode->set_process_write(
+      envoy::extensions::filters::network::ext_proc::v3::ProcessingMode::SKIP);
+
+  NiceMock<Server::Configuration::MockFactoryContext> context;
+  NetworkExtProcConfigFactory factory;
+
+  EXPECT_THROW_WITH_MESSAGE(auto cb = factory.createFilterFactoryFromProto(proto_config, context),
+                            EnvoyException,
+                            "both read and write paths are skipped, at least one must be enabled.");
+}
+
+// Test the configs with default processing modes.
+TEST(NetworkExtProcConfigFactoryTest, DefaultProcessingMode) {
+  envoy::extensions::filters::network::ext_proc::v3::NetworkExternalProcessor proto_config;
+  proto_config.mutable_grpc_service()->mutable_envoy_grpc()->set_cluster_name("ext_proc_server");
+
+  NiceMock<Server::Configuration::MockFactoryContext> context;
+  NetworkExtProcConfigFactory factory;
+
+  EXPECT_NO_THROW(auto cb = factory.createFilterFactoryFromProto(proto_config, context));
+}
+
 } // namespace
 } // namespace ExtProc
 } // namespace NetworkFilters

tools/code_format/config.yaml

@@ -192,6 +192,7 @@ paths:
     - source/extensions/filters/network/redis_proxy
     - source/extensions/filters/network/zookeeper_proxy
     - source/extensions/filters/network/ext_authz
+    - source/extensions/filters/network/ext_proc
     - source/extensions/filters/network/mongo_proxy
     - source/extensions/filters/network/thrift_proxy
     - source/extensions/filters/network/generic_proxy