filter state: register DFP objects

Signed-off-by: Kuat Yessenov <[email protected]>

docs/root/configuration/advanced/well_known_filter_state.rst

@@ -13,9 +13,16 @@ The following list of filter state objects are consumed by Envoy extensions:
    * - **Filter state key**
      - **Purpose**
    * - ``envoy.tcp_proxy.cluster``
-     - :ref:`TCP proxy <config_network_filters_tcp_proxy>` dynamic cluster selection on a per-connection basis.
+     - | :ref:`TCP proxy <config_network_filters_tcp_proxy>` dynamic cluster name selection
+       | on a per-connection basis.
    * - ``envoy.network.transport_socket.original_dst_address``
      - | :ref:`Original destination cluster <arch_overview_load_balancing_types_original_destination>` dynamic address selection.
        | Fields:
        | - *ip*: IP address value;
        | - *port*: port value.
+   * - ``envoy.upstream.dynamic_host``
+     - | :ref:`Dynamic forward proxy <envoy_v3_api_msg_extensions.clusters.dynamic_forward_proxy.v3.ClusterConfig>``
+       | upstream host override on a per-connection basis.
+   * - ``envoy.upstream.dynamic_port``
+     - | :ref:`Dynamic forward proxy <envoy_v3_api_msg_extensions.clusters.dynamic_forward_proxy.v3.ClusterConfig>``
+       | upstream port override on a per-connection basis.

source/common/stream_info/uint32_accessor_impl.h

@@ -18,6 +18,9 @@ class UInt32AccessorImpl : public UInt32Accessor {
     message->set_value(value_);
     return message;
   }
+  absl::optional<std::string> serializeAsString() const override {
+    return absl::StrCat(value_);
+  }
 
   // From UInt32Accessor.
   void increment() override { value_++; }

source/extensions/clusters/dynamic_forward_proxy/BUILD

@@ -20,6 +20,8 @@ envoy_cc_extension(
         "//source/extensions/common/dynamic_forward_proxy:cluster_store",
         "//source/extensions/common/dynamic_forward_proxy:dns_cache_interface",
         "//source/extensions/common/dynamic_forward_proxy:dns_cache_manager_impl",
+        "//source/common/router:string_accessor_lib",
+        "//source/common/stream_info:uint32_accessor_lib",
         "//source/extensions/transport_sockets/tls/cert_validator:cert_validator_lib",
         "@envoy_api//envoy/config/cluster/v3:pkg_cc_proto",
         "@envoy_api//envoy/config/endpoint/v3:pkg_cc_proto",

source/extensions/clusters/dynamic_forward_proxy/cluster.cc

@@ -10,6 +10,8 @@
 
 #include "source/common/http/utility.h"
 #include "source/common/network/transport_socket_options_impl.h"
+#include "source/common/router/string_accessor_impl.h"
+#include "source/common/stream_info/uint32_accessor_impl.h"
 #include "source/extensions/common/dynamic_forward_proxy/dns_cache_manager_impl.h"
 #include "source/extensions/transport_sockets/tls/cert_validator/default_validator.h"
 #include "source/extensions/transport_sockets/tls/utility.h"
@@ -19,6 +21,36 @@ namespace Extensions {
 namespace Clusters {
 namespace DynamicForwardProxy {
 
+namespace {
+constexpr absl::string_view DynamicHostFilterStateKey = "envoy.upstream.dynamic_host";
+constexpr absl::string_view DynamicPortFilterStateKey = "envoy.upstream.dynamic_port";
+
+class DynamicHostObjectFactory : public StreamInfo::FilterState::ObjectFactory {
+public:
+  std::string name() const override { return std::string(DynamicHostFilterStateKey); }
+  std::unique_ptr<StreamInfo::FilterState::Object>
+  createFromBytes(absl::string_view data) const override {
+    return std::make_unique<Router::StringAccessorImpl>(data);
+  }
+};
+class DynamicPortObjectFactory : public StreamInfo::FilterState::ObjectFactory {
+public:
+  std::string name() const override { return std::string(DynamicPortFilterStateKey); }
+  std::unique_ptr<StreamInfo::FilterState::Object>
+  createFromBytes(absl::string_view data) const override {
+    uint32_t port = 0;
+    if (absl::SimpleAtoi(data, &port)) {
+      return std::make_unique<StreamInfo::UInt32AccessorImpl>(port);
+    }
+    return nullptr;
+  }
+};
+
+} // namespace
+
+REGISTER_FACTORY(DynamicHostObjectFactory, StreamInfo::FilterState::ObjectFactory);
+REGISTER_FACTORY(DynamicPortObjectFactory, StreamInfo::FilterState::ObjectFactory);
+
 Cluster::Cluster(
     const envoy::config::cluster::v3::Cluster& cluster,
     const envoy::extensions::clusters::dynamic_forward_proxy::v3::ClusterConfig& config,
@@ -316,7 +348,7 @@ Cluster::LoadBalancer::chooseHost(Upstream::LoadBalancerContext* context) {
         context->downstreamConnection()
             ->streamInfo()
             .filterState()
-            .getDataReadOnly<Router::StringAccessor>("envoy.upstream.dynamic_host");
+            .getDataReadOnly<Router::StringAccessor>(DynamicHostFilterStateKey);
   }
 
   absl::string_view raw_host;
@@ -343,7 +375,7 @@ Cluster::LoadBalancer::chooseHost(Upstream::LoadBalancerContext* context) {
         context->downstreamConnection()
             ->streamInfo()
             .filterState()
-            .getDataReadOnly<StreamInfo::UInt32Accessor>("envoy.upstream.dynamic_port");
+            .getDataReadOnly<StreamInfo::UInt32Accessor>(DynamicPortFilterStateKey);
     if (dynamic_port_filter_state != nullptr && dynamic_port_filter_state->value() > 0 &&
         dynamic_port_filter_state->value() <= 65535) {
       port = dynamic_port_filter_state->value();

test/extensions/clusters/dynamic_forward_proxy/cluster_test.cc

@@ -722,6 +722,31 @@ connect_timeout: 0.25s
   EXPECT_THROW(createCluster(yaml_config), EnvoyException);
 }
 
+TEST(ObjectFactory, DynamicHost) {
+  const std::string name = "envoy.upstream.dynamic_host";
+  auto* factory =
+      Registry::FactoryRegistry<StreamInfo::FilterState::ObjectFactory>::getFactory(name);
+  ASSERT_NE(nullptr, factory);
+  EXPECT_EQ(name, factory->name());
+  const std::string host = "site.com";
+  auto object = factory->createFromBytes(host);
+  ASSERT_NE(nullptr, object);
+  EXPECT_EQ(host, object->serializeAsString());
+}
+
+TEST(ObjectFactory, DynamicPort) {
+  const std::string name = "envoy.upstream.dynamic_port";
+  auto* factory =
+      Registry::FactoryRegistry<StreamInfo::FilterState::ObjectFactory>::getFactory(name);
+  ASSERT_NE(nullptr, factory);
+  EXPECT_EQ(name, factory->name());
+  const std::string port = "8080";
+  auto object = factory->createFromBytes(port);
+  ASSERT_NE(nullptr, object);
+  EXPECT_EQ(port, object->serializeAsString());
+  ASSERT_EQ(nullptr, factory->createFromBytes("blah"));
+}
+
 } // namespace DynamicForwardProxy
 } // namespace Clusters
 } // namespace Extensions