matching: add support for generic inputs and add environment variable input

CODEOWNERS

@@ -166,6 +166,8 @@ extensions/filters/http/oauth2 @rgs1 @derekargueta @snowp
 /*/extensions/rate_limit_descriptors/expr @kyessenov @lizan
 # hash input matcher
 /*/extensions/matching/input_matchers/consistent_hashing @snowp @donyu
+# environment generic input
+/*/extensions/matching/common_inputs/environment @snowp @donyu
 # user space socket pair and event
 /*/extensions/io_socket/user_space @lambdai @antoniovicente
 # Default UUID4 request ID extension

api/BUILD

@@ -246,6 +246,7 @@ proto_library(
         "//envoy/extensions/internal_redirect/allow_listed_routes/v3:pkg",
         "//envoy/extensions/internal_redirect/previous_routes/v3:pkg",
         "//envoy/extensions/internal_redirect/safe_cross_scheme/v3:pkg",
+        "//envoy/extensions/matching/common_inputs/environment_variable/v3:pkg",
         "//envoy/extensions/matching/input_matchers/consistent_hashing/v3:pkg",
         "//envoy/extensions/network/socket_interface/v3:pkg",
         "//envoy/extensions/rate_limit_descriptors/expr/v3:pkg",

api/envoy/config/common/matcher/v3/matcher.proto

@@ -50,6 +50,7 @@ message Matcher {
       // Predicate for a single input field.
       message SinglePredicate {
         // Protocol-specific specification of input field to match on.
+        // [#extension-category: envoy.matching.common_inputs]
         core.v3.TypedExtensionConfig input = 1 [(validate.rules).message = {required: true}];
 
         oneof matcher {

api/envoy/extensions/matching/common_inputs/environment_variable/v3/BUILD

@@ -0,0 +1,9 @@
+# DO NOT EDIT. This file is generated by tools/proto_format/proto_sync.py.
+
+load("@envoy_api//bazel:api_build_system.bzl", "api_proto_package")
+
+licenses(["notice"])  # Apache 2
+
+api_proto_package(
+    deps = ["@com_github_cncf_udpa//udpa/annotations:pkg"],
+)

api/envoy/extensions/matching/common_inputs/environment_variable/v3/input.proto

@@ -0,0 +1,22 @@
+syntax = "proto3";
+
+package envoy.extensions.matching.common_inputs.environment_variable.v3;
+
+import "udpa/annotations/migrate.proto";
+import "udpa/annotations/status.proto";
+import "udpa/annotations/versioning.proto";
+import "validate/validate.proto";
+
+option java_package = "io.envoyproxy.envoy.extensions.matching.common_inputs.environment_variable.v3";
+option java_outer_classname = "InputProto";
+option java_multiple_files = true;
+option (udpa.annotations.file_status).package_version_status = ACTIVE;
+
+// [#protodoc-title: Environment Variable Input]
+// [#extension: envoy.matching.common_inputs.environment_variable]
+
+// Reads an environment variable to provide an input for matching.
+message Config {
+  // Name of the environment variable to read from.
+  string name = 1 [(validate.rules).string = {min_len: 1}];
+}

api/versioning/BUILD

@@ -129,6 +129,7 @@ proto_library(
         "//envoy/extensions/internal_redirect/allow_listed_routes/v3:pkg",
         "//envoy/extensions/internal_redirect/previous_routes/v3:pkg",
         "//envoy/extensions/internal_redirect/safe_cross_scheme/v3:pkg",
+        "//envoy/extensions/matching/common_inputs/environment_variable/v3:pkg",
         "//envoy/extensions/matching/input_matchers/consistent_hashing/v3:pkg",
         "//envoy/extensions/network/socket_interface/v3:pkg",
         "//envoy/extensions/rate_limit_descriptors/expr/v3:pkg",

bazel/envoy_library.bzl

@@ -83,6 +83,7 @@ EXTENSION_CATEGORIES = [
     "envoy.http.stateful_header_formatters",
     "envoy.internal_redirect_predicates",
     "envoy.io_socket",
+    "envoy.matching.common_inputs",
     "envoy.matching.input_matchers",
     "envoy.rate_limit_descriptors",
     "envoy.request_id",

docs/root/api-v3/common_messages/common_messages.rst

@@ -26,3 +26,4 @@ Common messages
   ../extensions/filters/common/dependency/v3/dependency.proto
   ../extensions/filters/common/matcher/action/v3/skip_action.proto
   ../extensions/matching/input_matchers/consistent_hashing/v3/consistent_hashing.proto
+  ../extensions/matching/common_inputs/environment_variable/v3/input.proto

generated_api_shadow/BUILD

@@ -246,6 +246,7 @@ proto_library(
         "//envoy/extensions/internal_redirect/allow_listed_routes/v3:pkg",
         "//envoy/extensions/internal_redirect/previous_routes/v3:pkg",
         "//envoy/extensions/internal_redirect/safe_cross_scheme/v3:pkg",
+        "//envoy/extensions/matching/common_inputs/environment_variable/v3:pkg",
         "//envoy/extensions/matching/input_matchers/consistent_hashing/v3:pkg",
         "//envoy/extensions/network/socket_interface/v3:pkg",
         "//envoy/extensions/rate_limit_descriptors/expr/v3:pkg",

include/envoy/matcher/matcher.h

@@ -201,7 +201,8 @@ struct DataInputGetResult {
 };
 
 /**
- * Interface for types providing a way to extract a string from the DataType to perform matching on.
+ * Interface for types providing a way to extract a string from the DataType to perform matching
+ * on.
  */
 template <class DataType> class DataInput {
 public:
@@ -236,5 +237,31 @@ template <class DataType> class DataInputFactory : public Config::TypedFactory {
   }
 };
 
+/**
+ * Interface for types providing a way to use a string for matching without depending on protocol
+ * data. As a result, these can be used for all protocols.
+ */
+class CommonProtocolInput {
+public:
+  virtual ~CommonProtocolInput() = default;
+  virtual absl::optional<absl::string_view> get() PURE;
+};
+using CommonProtocolInputPtr = std::unique_ptr<CommonProtocolInput>;
+
+/**
+ * Factory for CommonProtocolInput.
+ */
+class CommonProtocolInputFactory : public Config::TypedFactory {
+public:
+  /**
+   * Creates a CommonProtocolInput from the provided config.
+   */
+  virtual CommonProtocolInputPtr
+  createCommonProtocolInput(const Protobuf::Message& config,
+                            Server::Configuration::FactoryContext& factory_context) PURE;
+
+  std::string category() const override { return "envoy.matching.common_inputs"; }
+};
+
 } // namespace Matcher
 } // namespace Envoy

source/common/matcher/matcher.h

@@ -155,12 +155,38 @@ template <class DataType> class MatchTreeFactory {
     return absl::nullopt;
   }
 
+  // Wrapper around a CommonProtocolInput that allows it to be used as a DataInput<DataType>.
+  class CommonProtocolInputWrapper : public DataInput<DataType> {
+  public:
+    explicit CommonProtocolInputWrapper(CommonProtocolInputPtr&& common_protocol_input)
+        : common_protocol_input_(std::move(common_protocol_input)) {}
+
+    DataInputGetResult get(const DataType&) override {
+      return DataInputGetResult{DataInputGetResult::DataAvailability::AllDataAvailable,
+                                common_protocol_input_->get()};
+    }
+
+  private:
+    const CommonProtocolInputPtr common_protocol_input_;
+  };
+
   DataInputPtr<DataType>
   createDataInput(const envoy::config::core::v3::TypedExtensionConfig& config) {
-    auto& factory = Config::Utility::getAndCheckFactory<DataInputFactory<DataType>>(config);
+    auto* factory = Config::Utility::getFactory<DataInputFactory<DataType>>(config);
+    if (factory != nullptr) {
+      ProtobufTypes::MessagePtr message = Config::Utility::translateAnyToFactoryConfig(
+          config.typed_config(), factory_context_.messageValidationVisitor(), *factory);
+      return factory->createDataInput(*message, factory_context_);
+    }
+
+    // If the provided config doesn't match a typed input, assume that this is one of the common
+    // inputs.
+    auto& common_input_factory =
+        Config::Utility::getAndCheckFactory<CommonProtocolInputFactory>(config);
     ProtobufTypes::MessagePtr message = Config::Utility::translateAnyToFactoryConfig(
-        config.typed_config(), factory_context_.messageValidationVisitor(), factory);
-    return factory.createDataInput(*message, factory_context_);
+        config.typed_config(), factory_context_.messageValidationVisitor(), common_input_factory);
+    return std::make_unique<CommonProtocolInputWrapper>(
+        common_input_factory.createCommonProtocolInput(*message, factory_context_));
   }
 
   InputMatcherPtr createInputMatcher(

source/extensions/extensions_build_config.bzl

@@ -53,6 +53,12 @@ EXTENSIONS = {
 
     "envoy.matching.input_matchers.consistent_hashing":       "//source/extensions/matching/input_matchers/consistent_hashing:config",
 
+    #
+    # Generic Inputs
+    #
+
+    "envoy.matching.common_inputs.environment_variable":       "//source/extensions/matching/common_inputs/environment_variable:config",
+
     #
     # HTTP filters
     #

source/extensions/matching/common_inputs/environment_variable/BUILD

@@ -0,0 +1,34 @@
+load(
+    "//bazel:envoy_build_system.bzl",
+    "envoy_cc_extension",
+    "envoy_cc_library",
+    "envoy_extension_package",
+)
+
+licenses(["notice"])  # Apache 2
+
+envoy_extension_package()
+
+envoy_cc_library(
+    name = "input_lib",
+    hdrs = ["input.h"],
+    deps = [
+        "//include/envoy/matcher:matcher_interface",
+        "//source/common/common:hash_lib",
+    ],
+)
+
+envoy_cc_extension(
+    name = "config",
+    srcs = ["config.cc"],
+    hdrs = ["config.h"],
+    category = "envoy.matching.common_inputs",
+    security_posture = "robust_to_untrusted_downstream",
+    deps = [
+        ":input_lib",
+        "//include/envoy/matcher:matcher_interface",
+        "//include/envoy/registry",
+        "//include/envoy/server:factory_context_interface",
+        "@envoy_api//envoy/extensions/matching/common_inputs/environment_variable/v3:pkg_cc_proto",
+    ],
+)

source/extensions/matching/common_inputs/environment_variable/config.cc

@@ -0,0 +1,39 @@
+#include "extensions/matching/common_inputs/environment_variable/config.h"
+
+#include <memory>
+
+#include "envoy/matcher/matcher.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Matching {
+namespace CommonInputs {
+namespace EnvironmentVariable {
+
+Envoy::Matcher::CommonProtocolInputPtr
+Config::createCommonProtocolInput(const Protobuf::Message& config,
+                                  Server::Configuration::FactoryContext& factory_context) {
+  const auto& environment_config = MessageUtil::downcastAndValidate<
+      const envoy::extensions::matching::common_inputs::environment_variable::v3::Config&>(
+      config, factory_context.messageValidationVisitor());
+
+  // We read the env variable at construction time to avoid repeat lookups.
+  // This assumes that the environment remains stable during the process lifetime.
+  auto* value = getenv(environment_config.name().data());
+  if (value != nullptr) {
+    return std::make_unique<Input>(std::string(value));
+  }
+
+  return std::make_unique<Input>(absl::nullopt);
+}
+
+/**
+ * Static registration for the environment data input. @see RegisterFactory.
+ */
+REGISTER_FACTORY(Config, Envoy::Matcher::CommonProtocolInputFactory);
+
+} // namespace EnvironmentVariable
+} // namespace CommonInputs
+} // namespace Matching
+} // namespace Extensions
+} // namespace Envoy

source/extensions/matching/common_inputs/environment_variable/config.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include "envoy/extensions/matching/common_inputs/environment_variable/v3/input.pb.h"
+#include "envoy/extensions/matching/common_inputs/environment_variable/v3/input.pb.validate.h"
+#include "envoy/matcher/matcher.h"
+#include "envoy/server/factory_context.h"
+
+#include "common/protobuf/utility.h"
+
+#include "extensions/matching/common_inputs/environment_variable/input.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Matching {
+namespace CommonInputs {
+namespace EnvironmentVariable {
+
+class Config : public Envoy::Matcher::CommonProtocolInputFactory {
+public:
+  Envoy::Matcher::CommonProtocolInputPtr
+  createCommonProtocolInput(const Protobuf::Message& config,
+                            Server::Configuration::FactoryContext& factory_context) override;
+
+  std::string name() const override { return "envoy.matching.common_inputs.environment_variable"; }
+
+  ProtobufTypes::MessagePtr createEmptyConfigProto() override {
+    return std::make_unique<
+        envoy::extensions::matching::common_inputs::environment_variable::v3::Config>();
+  }
+};
+} // namespace EnvironmentVariable
+} // namespace CommonInputs
+} // namespace Matching
+} // namespace Extensions
+} // namespace Envoy

source/extensions/matching/common_inputs/environment_variable/input.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "envoy/matcher/matcher.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace Matching {
+namespace CommonInputs {
+namespace EnvironmentVariable {
+
+class Input : public Matcher::CommonProtocolInput {
+public:
+  explicit Input(absl::optional<std::string>&& value) : storage_(std::move(value)) {}
+
+  absl::optional<absl::string_view> get() override { return storage_; }
+
+private:
+  const absl::optional<std::string> storage_;
+};
+} // namespace EnvironmentVariable
+} // namespace CommonInputs
+} // namespace Matching
+} // namespace Extensions
+} // namespace Envoy