router: add config to send date header with requests

api/envoy/extensions/filters/http/router/v3/router.proto

@@ -19,7 +19,7 @@ option (udpa.annotations.file_status).package_version_status = ACTIVE;
 // Router :ref:`configuration overview <config_http_filters_router>`.
 // [#extension: envoy.filters.http.router]
 
-// [#next-free-field: 7]
+// [#next-free-field: 8]
 message Router {
   option (udpa.annotations.versioning).previous_message_type =
       "envoy.config.filter.http.router.v2.Router";
@@ -35,9 +35,9 @@ message Router {
   bool start_child_span = 2;
 
   // Configuration for HTTP upstream logs emitted by the router. Upstream logs
-  // are configured in the same way as access logs, but each log entry represents
-  // an upstream request. Presuming retries are configured, multiple upstream
-  // requests may be made for each downstream (inbound) request.
+  // are configured in the same way as access logs, but each log entry
+  // represents an upstream request. Presuming retries are configured, multiple
+  // upstream requests may be made for each downstream (inbound) request.
   repeated config.accesslog.v3.AccessLog upstream_log = 3;
 
   // Do not add any additional *x-envoy-* headers to requests or responses. This
@@ -75,7 +75,11 @@ message Router {
   }];
 
   // If not set, ingress Envoy will ignore
-  // :ref:`config_http_filters_router_x-envoy-expected-rq-timeout-ms` header, populated by egress
-  // Envoy, when deriving timeout for upstream cluster.
+  // :ref:`config_http_filters_router_x-envoy-expected-rq-timeout-ms` header,
+  // populated by egress Envoy, when deriving timeout for upstream cluster.
   bool respect_expected_rq_timeout = 6;
+
+  // Enable the addition of the `Date` header to outbound requests.
+  // If `true`, the header will be assigned on each request (and retry).
+  bool add_request_date_header = 7;
 }

include/envoy/http/header_map.h

@@ -300,7 +300,6 @@ class HeaderEntry {
  * Default O(1) response headers.
  */
 #define INLINE_RESP_HEADERS(HEADER_FUNC)                                                           \
-  HEADER_FUNC(Date)                                                                                \
   HEADER_FUNC(EnvoyDegraded)                                                                       \
   HEADER_FUNC(EnvoyImmediateHealthCheckFail)                                                       \
   HEADER_FUNC(EnvoyRateLimited)                                                                    \
@@ -318,6 +317,7 @@ class HeaderEntry {
   HEADER_FUNC(Connection)                                                                          \
   HEADER_FUNC(ContentLength)                                                                       \
   HEADER_FUNC(ContentType)                                                                         \
+  HEADER_FUNC(Date)                                                                                \
   HEADER_FUNC(EnvoyAttemptCount)                                                                   \
   HEADER_FUNC(EnvoyDecoratorOperation)                                                             \
   HEADER_FUNC(KeepAlive)                                                                           \

source/common/http/async_client_impl.cc

@@ -43,7 +43,7 @@ AsyncClientImpl::AsyncClientImpl(Upstream::ClusterInfoConstSharedPtr cluster,
                                  Router::ShadowWriterPtr&& shadow_writer,
                                  Http::Context& http_context)
     : cluster_(cluster), config_("http.async-client.", local_info, stats_store, cm, runtime, random,
-                                 std::move(shadow_writer), true, false, false, false, {},
+                                 std::move(shadow_writer), true, false, false, false, false, {},
                                  dispatcher.timeSource(), http_context),
       dispatcher_(dispatcher) {}
 

source/common/http/date_provider.h

@@ -14,10 +14,10 @@ class DateProvider {
   virtual ~DateProvider() = default;
 
   /**
-   * Set the Date header potentially using a cached value.
-   * @param headers supplies the headers to fill.
+   * Set the `Date` header (potentially using a cached value).
+   * @param headers the headers to populate.
    */
-  virtual void setDateHeader(ResponseHeaderMap& headers) PURE;
+  virtual void setDateHeader(RequestOrResponseHeaderMap& headers) PURE;
 };
 
 } // namespace Http

source/common/http/date_provider_impl.cc

@@ -25,11 +25,11 @@ void TlsCachingDateProviderImpl::onRefreshDate() {
   refresh_timer_->enableTimer(std::chrono::milliseconds(500));
 }
 
-void TlsCachingDateProviderImpl::setDateHeader(ResponseHeaderMap& headers) {
+void TlsCachingDateProviderImpl::setDateHeader(RequestOrResponseHeaderMap& headers) {
   headers.setDate(tls_->getTyped<ThreadLocalCachedDate>().date_string_);
 }
 
-void SlowDateProviderImpl::setDateHeader(ResponseHeaderMap& headers) {
+void SlowDateProviderImpl::setDateHeader(RequestOrResponseHeaderMap& headers) {
   headers.setDate(date_formatter_.now(time_source_));
 }
 

source/common/http/date_provider_impl.h

@@ -35,7 +35,7 @@ class TlsCachingDateProviderImpl : public DateProviderImplBase, public Singleton
   TlsCachingDateProviderImpl(Event::Dispatcher& dispatcher, ThreadLocal::SlotAllocator& tls);
 
   // Http::DateProvider
-  void setDateHeader(ResponseHeaderMap& headers) override;
+  void setDateHeader(RequestOrResponseHeaderMap& headers) override;
 
 private:
   struct ThreadLocalCachedDate : public ThreadLocal::ThreadLocalObject {
@@ -58,7 +58,7 @@ class SlowDateProviderImpl : public DateProviderImplBase {
 
 public:
   // Http::DateProvider
-  void setDateHeader(ResponseHeaderMap& headers) override;
+  void setDateHeader(RequestOrResponseHeaderMap& headers) override;
 };
 
 } // namespace Http

source/common/router/BUILD

@@ -300,6 +300,7 @@ envoy_cc_library(
         "//source/common/common:utility_lib",
         "//source/common/grpc:common_lib",
         "//source/common/http:codes_lib",
+        "//source/common/http:date_provider_lib",
         "//source/common/http:header_map_lib",
         "//source/common/http:headers_lib",
         "//source/common/http:message_lib",

source/common/router/router.cc

@@ -331,6 +331,10 @@ Http::FilterHeadersStatus Filter::decodeHeaders(Http::RequestHeaderMap& headers,
   ASSERT(headers.Method());
   ASSERT(headers.Host());
 
+  if (config_.add_request_date_header_) {
+    config_.date_provider_.setDateHeader(headers);
+  }
+
   downstream_headers_ = &headers;
 
   // Extract debug configuration from filter state. This is used further along to determine whether
@@ -1525,6 +1529,10 @@ void Filter::doRetry() {
     downstream_headers_->setEnvoyAttemptCount(attempt_count_);
   }
 
+  if (config_.add_request_date_header_) {
+    config_.date_provider_.setDateHeader(*downstream_headers_);
+  }
+
   UpstreamRequest* upstream_request_tmp = upstream_request.get();
   upstream_request->moveIntoList(std::move(upstream_request), upstream_requests_);
   upstream_requests_.front()->encodeHeaders(!callbacks_->decodingBuffer() &&

source/common/router/router.h

@@ -26,6 +26,7 @@
 #include "common/common/linked_object.h"
 #include "common/common/logger.h"
 #include "common/config/well_known_names.h"
+#include "common/http/date_provider_impl.h"
 #include "common/http/utility.h"
 #include "common/router/config_impl.h"
 #include "common/router/upstream_request.h"
@@ -182,14 +183,16 @@ class FilterConfig {
                Stats::Scope& scope, Upstream::ClusterManager& cm, Runtime::Loader& runtime,
                Runtime::RandomGenerator& random, ShadowWriterPtr&& shadow_writer,
                bool emit_dynamic_stats, bool start_child_span, bool suppress_envoy_headers,
-               bool respect_expected_rq_timeout,
+               bool respect_expected_rq_timeout, bool add_request_date_header,
                const Protobuf::RepeatedPtrField<std::string>& strict_check_headers,
                TimeSource& time_source, Http::Context& http_context)
       : scope_(scope), local_info_(local_info), cm_(cm), runtime_(runtime),
         random_(random), stats_{ALL_ROUTER_STATS(POOL_COUNTER_PREFIX(scope, stat_prefix))},
         emit_dynamic_stats_(emit_dynamic_stats), start_child_span_(start_child_span),
         suppress_envoy_headers_(suppress_envoy_headers),
-        respect_expected_rq_timeout_(respect_expected_rq_timeout), http_context_(http_context),
+        respect_expected_rq_timeout_(respect_expected_rq_timeout),
+        add_request_date_header_(add_request_date_header), http_context_(http_context),
+        date_provider_(Http::SlowDateProviderImpl(time_source)),
         stat_name_pool_(scope_.symbolTable()), retry_(stat_name_pool_.add("retry")),
         zone_name_(stat_name_pool_.add(local_info_.zoneName())),
         empty_stat_name_(stat_name_pool_.add("")), shadow_writer_(std::move(shadow_writer)),
@@ -209,8 +212,9 @@ class FilterConfig {
                      context.runtime(), context.random(), std::move(shadow_writer),
                      PROTOBUF_GET_WRAPPED_OR_DEFAULT(config, dynamic_stats, true),
                      config.start_child_span(), config.suppress_envoy_headers(),
-                     config.respect_expected_rq_timeout(), config.strict_check_headers(),
-                     context.api().timeSource(), context.httpContext()) {
+                     config.respect_expected_rq_timeout(), config.add_request_date_header(),
+                     config.strict_check_headers(), context.api().timeSource(),
+                     context.httpContext()) {
     for (const auto& upstream_log : config.upstream_log()) {
       upstream_logs_.push_back(AccessLog::AccessLogFactory::fromProto(upstream_log, context));
     }
@@ -231,10 +235,12 @@ class FilterConfig {
   const bool start_child_span_;
   const bool suppress_envoy_headers_;
   const bool respect_expected_rq_timeout_;
+  const bool add_request_date_header_;
   // TODO(xyu-stripe): Make this a bitset to keep cluster memory footprint down.
   HeaderVectorPtr strict_check_headers_;
   std::list<AccessLog::InstanceSharedPtr> upstream_logs_;
   Http::Context& http_context_;
+  Http::SlowDateProviderImpl date_provider_;
   Stats::StatNamePool stat_name_pool_;
   Stats::StatName retry_;
   Stats::StatName zone_name_;

test/common/http/date_provider_impl_test.cc

@@ -11,11 +11,63 @@
 #include "gtest/gtest.h"
 
 using testing::NiceMock;
+using testing::Return;
 
 namespace Envoy {
 namespace Http {
 
-TEST(DateProviderImplTest, All) {
+class MockTimeSource : public TimeSource {
+public:
+  MOCK_METHOD(SystemTime, systemTime, ());
+  MOCK_METHOD(MonotonicTime, monotonicTime, ());
+};
+
+TEST(SlowDateProviderImplTest, RequestHeaders) {
+  MockTimeSource time_source;
+  SystemTime time_point{SystemTime::duration(2000000)};
+  EXPECT_CALL(time_source, systemTime()).WillOnce(Return(time_point));
+
+  SlowDateProviderImpl provider(time_source);
+  TestRequestHeaderMapImpl headers;
+  EXPECT_EQ(nullptr, headers.Date());
+
+  provider.setDateHeader(headers);
+  EXPECT_EQ(headers.get_("date"), "Thu, 01 Jan 1970 00:00:02 GMT");
+}
+
+TEST(SlowDateProviderImplTest, ResponseHeaders) {
+  MockTimeSource time_source;
+  SystemTime time_point{SystemTime::duration(2000000)};
+  EXPECT_CALL(time_source, systemTime()).WillOnce(Return(time_point));
+
+  SlowDateProviderImpl provider(time_source);
+  TestResponseHeaderMapImpl headers;
+  EXPECT_EQ(nullptr, headers.Date());
+
+  provider.setDateHeader(headers);
+  EXPECT_EQ(headers.Date()->value(), "Thu, 01 Jan 1970 00:00:02 GMT");
+}
+
+TEST(TlsCachingDateProviderImplTest, TlsRequestHeaders) {
+  Event::MockDispatcher dispatcher;
+  NiceMock<ThreadLocal::MockInstance> tls;
+  Event::MockTimer* timer = new Event::MockTimer(&dispatcher);
+  EXPECT_CALL(*timer, enableTimer(std::chrono::milliseconds(500), _));
+
+  TlsCachingDateProviderImpl provider(dispatcher, tls);
+  TestRequestHeaderMapImpl headers;
+  provider.setDateHeader(headers);
+  EXPECT_NE(nullptr, headers.Date());
+
+  EXPECT_CALL(*timer, enableTimer(std::chrono::milliseconds(500), _));
+  timer->invokeCallback();
+
+  headers.removeDate();
+  provider.setDateHeader(headers);
+  EXPECT_NE(nullptr, headers.Date());
+}
+
+TEST(TlsCachingDateProviderImplTest, TlsResponseHeaders) {
   Event::MockDispatcher dispatcher;
   NiceMock<ThreadLocal::MockInstance> tls;
   Event::MockTimer* timer = new Event::MockTimer(&dispatcher);