http: Introduce preserve_upstream_date option (#11077)

The preserve_upstream_date option allows the HTTP Connection Manager to be configured to pass through the original date header from the upstream response rather than overwriting it. The default behaviour for the date response header remains the same as before -- the header value will be overwritten by Envoy.

Signed-off-by: Craig Radcliffe <craig.radcliffe@broadcom.com>

api/envoy/extensions/filters/network/http_connection_manager/v3/http_connection_manager.proto

@@ -30,7 +30,7 @@ option (udpa.annotations.file_status).package_version_status = ACTIVE;
 // HTTP connection manager :ref:`configuration overview <config_http_conn_man>`.
 // [#extension: envoy.filters.network.http_connection_manager]
 
-// [#next-free-field: 38]
+// [#next-free-field: 39]
 message HttpConnectionManager {
   option (udpa.annotations.versioning).previous_message_type =
       "envoy.config.filter.network.http_connection_manager.v2.HttpConnectionManager";
@@ -506,6 +506,11 @@ message HttpConnectionManager {
   //
   // 3. Tracing decision (sampled, forced, etc) is set in 14th byte of the UUID.
   RequestIDExtension request_id_extension = 36;
+
+  // If `preserve_upstream_date` is true, the value of the `date` header sent by the upstream
+  // host will not be overwritten by the HTTP Connection Manager. The default behaviour is
+  // to overwrite the `date` header unconditionally.
+  bool preserve_upstream_date = 38;
 }
 
 message Rds {

api/envoy/extensions/filters/network/http_connection_manager/v4alpha/http_connection_manager.proto

@@ -30,7 +30,7 @@ option (udpa.annotations.file_status).package_version_status = NEXT_MAJOR_VERSIO
 // HTTP connection manager :ref:`configuration overview <config_http_conn_man>`.
 // [#extension: envoy.filters.network.http_connection_manager]
 
-// [#next-free-field: 38]
+// [#next-free-field: 39]
 message HttpConnectionManager {
   option (udpa.annotations.versioning).previous_message_type =
       "envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager";
@@ -506,6 +506,11 @@ message HttpConnectionManager {
   //
   // 3. Tracing decision (sampled, forced, etc) is set in 14th byte of the UUID.
   RequestIDExtension request_id_extension = 36;
+
+  // If `preserve_upstream_date` is true, the value of the `date` header sent by the upstream
+  // host will not be overwritten by the HTTP Connection Manager. The default behaviour is
+  // to overwrite the `date` header unconditionally.
+  bool preserve_upstream_date = 38;
 }
 
 message Rds {

source/common/http/conn_manager_config.h

@@ -430,6 +430,12 @@ class ConnectionManagerConfig {
    */
   virtual envoy::config::core::v3::HttpProtocolOptions::HeadersWithUnderscoresAction
   headersWithUnderscoresAction() const PURE;
+
+  /**
+   * @return if the HttpConnectionManager should preserve the `date` response header sent by the
+   * upstream host.
+   */
+  virtual bool shouldPreserveUpstreamDate() const PURE;
 };
 } // namespace Http
 } // namespace Envoy

source/common/http/conn_manager_impl.cc

@@ -1620,7 +1620,9 @@ void ConnectionManagerImpl::ActiveStream::encodeHeaders(ActiveStreamEncoderFilte
 void ConnectionManagerImpl::ActiveStream::encodeHeadersInternal(ResponseHeaderMap& headers,
                                                                 bool end_stream) {
   // Base headers.
-  connection_manager_.config_.dateProvider().setDateHeader(headers);
+  if (!connection_manager_.config_.shouldPreserveUpstreamDate() || !headers.Date()) {
+    connection_manager_.config_.dateProvider().setDateHeader(headers);
+  }
   // Following setReference() is safe because serverName() is constant for the life of the listener.
   const auto transformation = connection_manager_.config_.serverHeaderTransformation();
   if (transformation == ConnectionManagerConfig::HttpConnectionManagerProto::OVERWRITE ||

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

@@ -217,7 +217,8 @@ HttpConnectionManagerConfig::HttpConnectionManagerConfig(
 #endif
       merge_slashes_(config.merge_slashes()),
       headers_with_underscores_action_(
-          config.common_http_protocol_options().headers_with_underscores_action()) {
+          config.common_http_protocol_options().headers_with_underscores_action()),
+      preserve_upstream_date_(config.preserve_upstream_date()) {
   // If idle_timeout_ was not configured in common_http_protocol_options, use value in deprecated
   // idle_timeout field.
   // TODO(asraa): Remove when idle_timeout is removed.

source/extensions/filters/network/http_connection_manager/config.h

@@ -162,6 +162,7 @@ class HttpConnectionManagerConfig : Logger::Loggable<Logger::Id::config>,
     return headers_with_underscores_action_;
   }
   std::chrono::milliseconds delayedCloseTimeout() const override { return delayed_close_timeout_; }
+  bool shouldPreserveUpstreamDate() const override { return preserve_upstream_date_; }
 
 private:
   enum class CodecType { HTTP1, HTTP2, HTTP3, AUTO };
@@ -226,6 +227,7 @@ class HttpConnectionManagerConfig : Logger::Loggable<Logger::Id::config>,
   const bool merge_slashes_;
   const envoy::config::core::v3::HttpProtocolOptions::HeadersWithUnderscoresAction
       headers_with_underscores_action_;
+  const bool preserve_upstream_date_;
 
   // Default idle timeout is 5 minutes if nothing is specified in the HCM config.
   static const uint64_t StreamIdleTimeoutMs = 5 * 60 * 1000;

source/server/http/admin.h

@@ -168,6 +168,7 @@ class AdminImpl : public Admin,
   headersWithUnderscoresAction() const override {
     return envoy::config::core::v3::HttpProtocolOptions::ALLOW;
   }
+  bool shouldPreserveUpstreamDate() const override { return false; }
   Http::Code request(absl::string_view path_and_query, absl::string_view method,
                      Http::ResponseHeaderMap& response_headers, std::string& body) override;
   void closeSocket();

test/common/http/conn_manager_impl_fuzz_test.cc

@@ -160,6 +160,7 @@ class FuzzConfig : public ConnectionManagerConfig {
   headersWithUnderscoresAction() const override {
     return envoy::config::core::v3::HttpProtocolOptions::ALLOW;
   }
+  bool shouldPreserveUpstreamDate() const override { return false; }
 
   const envoy::extensions::filters::network::http_connection_manager::v3::HttpConnectionManager
       config_;

test/common/http/conn_manager_impl_test.cc

@@ -353,6 +353,7 @@ class HttpConnectionManagerImplTest : public testing::Test, public ConnectionMan
   headersWithUnderscoresAction() const override {
     return headers_with_underscores_action_;
   }
+  bool shouldPreserveUpstreamDate() const override { return preserve_upstream_date_; }
 
   Envoy::Event::SimulatedTimeSystem test_time_;
   NiceMock<Router::MockRouteConfigProvider> route_config_provider_;
@@ -414,6 +415,7 @@ class HttpConnectionManagerImplTest : public testing::Test, public ConnectionMan
   NiceMock<Network::MockClientConnection> upstream_conn_; // for websocket tests
   NiceMock<Tcp::ConnectionPool::MockInstance> conn_pool_; // for websocket tests
   RequestIDExtensionSharedPtr request_id_extension_;
+  bool preserve_upstream_date_ = false;
 
   // TODO(mattklein123): Not all tests have been converted over to better setup. Convert the rest.
   MockResponseEncoder response_encoder_;
@@ -897,6 +899,56 @@ TEST_F(HttpConnectionManagerImplTest, RouteShouldUseSantizedPath) {
   conn_manager_->onData(fake_input, false);
 }
 
+TEST_F(HttpConnectionManagerImplTest, PreserveUpstreamDateDisabledDateNotSet) {
+  setup(false, "");
+  setUpEncoderAndDecoder(false, false);
+  sendRequestHeadersAndData();
+  preserve_upstream_date_ = false;
+  const auto* modified_headers = sendResponseHeaders(
+      ResponseHeaderMapPtr{new TestResponseHeaderMapImpl{{":status", "200"}, {"server", "foo"}}});
+  ASSERT_TRUE(modified_headers);
+  EXPECT_TRUE(modified_headers->Date());
+}
+
+TEST_F(HttpConnectionManagerImplTest, PreserveUpstreamDateDisabledDateSet) {
+  setup(false, "");
+  setUpEncoderAndDecoder(false, false);
+  sendRequestHeadersAndData();
+  preserve_upstream_date_ = false;
+  const std::string expected_date{"Tue, 15 Nov 1994 08:12:31 GMT"};
+  const auto* modified_headers =
+      sendResponseHeaders(ResponseHeaderMapPtr{new TestResponseHeaderMapImpl{
+          {":status", "200"}, {"server", "foo"}, {"date", expected_date.c_str()}}});
+  ASSERT_TRUE(modified_headers);
+  ASSERT_TRUE(modified_headers->Date());
+  EXPECT_NE(expected_date, modified_headers->Date()->value().getStringView());
+}
+
+TEST_F(HttpConnectionManagerImplTest, PreserveUpstreamDateEnabledDateNotSet) {
+  setup(false, "");
+  setUpEncoderAndDecoder(false, false);
+  sendRequestHeadersAndData();
+  preserve_upstream_date_ = true;
+  const auto* modified_headers = sendResponseHeaders(
+      ResponseHeaderMapPtr{new TestResponseHeaderMapImpl{{":status", "200"}, {"server", "foo"}}});
+  ASSERT_TRUE(modified_headers);
+  EXPECT_TRUE(modified_headers->Date());
+}
+
+TEST_F(HttpConnectionManagerImplTest, PreserveUpstreamDateEnabledDateSet) {
+  setup(false, "");
+  setUpEncoderAndDecoder(false, false);
+  sendRequestHeadersAndData();
+  preserve_upstream_date_ = true;
+  const std::string expected_date{"Tue, 15 Nov 1994 08:12:31 GMT"};
+  const auto* modified_headers =
+      sendResponseHeaders(ResponseHeaderMapPtr{new TestResponseHeaderMapImpl{
+          {":status", "200"}, {"server", "foo"}, {"date", expected_date.c_str()}}});
+  ASSERT_TRUE(modified_headers);
+  ASSERT_TRUE(modified_headers->Date());
+  EXPECT_EQ(expected_date, modified_headers->Date()->value().getStringView());
+}
+
 TEST_F(HttpConnectionManagerImplTest, StartAndFinishSpanNormalFlow) {
   setup(false, "");
 

test/common/http/conn_manager_utility_test.cc

@@ -138,6 +138,7 @@ class MockConnectionManagerConfig : public ConnectionManagerConfig {
   MOCK_METHOD(bool, shouldMergeSlashes, (), (const));
   MOCK_METHOD(envoy::config::core::v3::HttpProtocolOptions::HeadersWithUnderscoresAction,
               headersWithUnderscoresAction, (), (const));
+  MOCK_METHOD(bool, shouldPreserveUpstreamDate, (), (const));
 
   std::unique_ptr<Http::InternalAddressConfig> internal_address_config_ =
       std::make_unique<DefaultInternalAddressConfig>();

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

@@ -1080,6 +1080,39 @@ TEST_F(HttpConnectionManagerConfigTest, UnconfiguredRequestTimeout) {
   EXPECT_EQ(0, config.requestTimeout().count());
 }
 
+TEST_F(HttpConnectionManagerConfigTest, DisabledPreserveResponseDate) {
+  const std::string yaml_string = R"EOF(
+  stat_prefix: ingress_http
+  request_timeout: 0s
+  route_config:
+    name: local_route
+  http_filters:
+  - name: envoy.filters.http.router
+  )EOF";
+
+  HttpConnectionManagerConfig config(parseHttpConnectionManagerFromV2Yaml(yaml_string), context_,
+                                     date_provider_, route_config_provider_manager_,
+                                     scoped_routes_config_provider_manager_, http_tracer_manager_);
+  EXPECT_FALSE(config.shouldPreserveUpstreamDate());
+}
+
+TEST_F(HttpConnectionManagerConfigTest, EnabledPreserveResponseDate) {
+  const std::string yaml_string = R"EOF(
+  stat_prefix: ingress_http
+  request_timeout: 0s
+  route_config:
+    name: local_route
+  http_filters:
+  - name: envoy.filters.http.router
+  preserve_upstream_date: true
+  )EOF";
+
+  HttpConnectionManagerConfig config(parseHttpConnectionManagerFromV2Yaml(yaml_string), context_,
+                                     date_provider_, route_config_provider_manager_,
+                                     scoped_routes_config_provider_manager_, http_tracer_manager_);
+  EXPECT_TRUE(config.shouldPreserveUpstreamDate());
+}
+
 TEST_F(HttpConnectionManagerConfigTest, SingleDateProvider) {
   const std::string yaml_string = R"EOF(
 codec_type: http1