matcher: add support for new any matcher mechanism

api/bazel/repository_locations.bzl

@@ -44,9 +44,9 @@ REPOSITORY_LOCATIONS_SPEC = dict(
         project_desc = "xDS API Working Group (xDS-WG)",
         project_url = "https://github.com/cncf/xds",
         # During the UDPA -> xDS migration, we aren't working with releases.
-        version = "cb28da3451f158a947dfc45090fe92b07b243bc1",
-        sha256 = "5bc8365613fe2f8ce6cc33959b7667b13b7fe56cb9d16ba740c06e1a7c4242fc",
-        release_date = "2021-10-11",
+        version = "a8f946100490e3c4aef5c069e41b58d1a8705836",
+        sha256 = "9822cb9550064c7575ca07516b7a2290808ccef8c311c486a295a41a323369ea",
+        release_date = "2021-11-30",
         strip_prefix = "xds-{version}",
         urls = ["https://github.com/cncf/xds/archive/{version}.tar.gz"],
         use_category = ["api"],

docs/root/version_history/current.rst

@@ -86,6 +86,7 @@ New Features
 * listener: added API for extensions to access :ref:`typed_filter_metadata <envoy_v3_api_field_config.core.v3.Metadata.typed_filter_metadata>` configured in the listener's :ref:`metadata <envoy_v3_api_field_config.listener.v3.Listener.metadata>` field.
 * listener: added support for :ref:`MPTCP <envoy_v3_api_field_config.listener.v3.Listener.enable_mptcp>` (multipath TCP).
 * listener: added support for opting out listeners from the globally set downstream connection limit via :ref:`ignore_global_conn_limit <envoy_v3_api_field_config.listener.v3.Listener.ignore_global_conn_limit>`.
+* matching: the matching API can now express a match tree that will always match by omitting a matcher at the top level.
 * oauth filter: added :ref:`cookie_names <envoy_v3_api_field_extensions.filters.http.oauth2.v3.OAuth2Credentials.cookie_names>` to allow overriding (default) cookie names (``BearerToken``, ``OauthHMAC``, and ``OauthExpires``) set by the filter.
 * oauth filter: setting IdToken and RefreshToken cookies if they are provided by Identity provider along with AccessToken.
 * perf: added support for [Perfetto](https://perfetto.dev) performance tracing.

source/common/matcher/matcher.h

@@ -65,6 +65,17 @@ using MatchTreeFactoryCb = std::function<std::unique_ptr<MatchTree<DataType>>()>
 template <class DataType> using OnMatchFactoryCb = std::function<OnMatch<DataType>()>;
 template <class DataType> using DataInputFactoryCb = std::function<DataInputPtr<DataType>()>;
 
+template <class DataType> class AnyMatcher : public MatchTree<DataType> {
+public:
+  explicit AnyMatcher(absl::optional<OnMatch<DataType>> on_no_match)
+      : on_no_match_(std::move(on_no_match)) {}
+
+  typename MatchTree<DataType>::MatchResult match(const DataType&) override {
+    return {MatchState::MatchComplete, on_no_match_};
+  }
+  const absl::optional<OnMatch<DataType>> on_no_match_;
+};
+
 /**
  * Recursively constructs a MatchTree from a protobuf configuration.
  * @param DataType the type used as a source for DataInputs
@@ -86,12 +97,20 @@ template <class DataType, class ActionFactoryContext> class MatchTreeFactory {
     case MatcherType::kMatcherList:
       return createListMatcher(config);
     default:
-      NOT_REACHED_GCOVR_EXCL_LINE;
-      return nullptr;
+      return createAnyMatcher(config);
     }
   }
 
 private:
+  template <class MatcherType>
+  MatchTreeFactoryCb<DataType> createAnyMatcher(const MatcherType& config) {
+    auto on_no_match = createOnMatch(config.on_no_match());
+
+    return [on_no_match]() {
+      return std::make_unique<AnyMatcher<DataType>>(
+          on_no_match ? absl::make_optional((*on_no_match)()) : absl::nullopt);
+    };
+  }
   template <class MatcherType>
   MatchTreeFactoryCb<DataType> createListMatcher(const MatcherType& config) {
     std::vector<std::pair<FieldMatcherFactoryCb<DataType>, OnMatchFactoryCb<DataType>>>

test/common/matcher/matcher_test.cc

@@ -17,6 +17,7 @@
 #include "test/test_common/utility.h"
 
 #include "gtest/gtest.h"
+#include "xds/type/matcher/v3/matcher.pb.validate.h"
 
 namespace Envoy {
 namespace Matcher {
@@ -83,6 +84,29 @@ TEST_F(MatcherTest, TestMatcher) {
   EXPECT_NE(result.on_match_->action_cb_, nullptr);
 }
 
+TEST_F(MatcherTest, TestAnyMatcher) {
+  const std::string yaml = R"EOF(
+on_no_match:
+  action:
+    name: test_action
+    typed_config:
+      "@type": type.googleapis.com/google.protobuf.StringValue
+      value: match!!
+  )EOF";
+
+  xds::type::matcher::v3::Matcher matcher;
+  MessageUtil::loadFromYaml(yaml, matcher, ProtobufMessage::getStrictValidationVisitor());
+
+  TestUtility::validate(matcher);
+
+  auto match_tree = factory_.create(matcher);
+
+  const auto result = match_tree()->match(TestData());
+  EXPECT_EQ(result.match_state_, MatchState::MatchComplete);
+  EXPECT_TRUE(result.on_match_.has_value());
+  EXPECT_NE(result.on_match_->action_cb_, nullptr);
+}
+
 TEST_F(MatcherTest, CustomGenericInput) {
   const std::string yaml = R"EOF(
 matcher_list: