Adds RouteEntry::requestHeaderTransforms. (envoyproxy#19621)

* Adds RouteEntry::requestHeaderTransforms. This new API works exactly the same as `ResponseEntry::responseHeaderTransforms` (see source/docs/response_header_transforms.md) except it gets transforms for request headers. Signed-off-by: Ming Zhou <[email protected]>
AppMonet · Jan 26, 2022 · fd3e837 · fd3e837
1 parent fcf2c55
commit fd3e837
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Showing 9 changed files with 361 additions and 146 deletions.
diff --git a/envoy/router/router.h b/envoy/router/router.h
@@ -763,6 +763,18 @@ class RouteEntry : public ResponseEntry {
                                       const StreamInfo::StreamInfo& stream_info,
                                       bool insert_envoy_original_path) const PURE;
 
+  /**
+   * Returns the request header transforms that would be applied if finalizeRequestHeaders were
+   * called now. This is useful if you want to obtain request header transforms which was or will be
+   * applied through finalizeRequestHeaders call. Note: do not use unless you are sure that there
+   * will be no route modifications later in the filter chain.
+   * @param stream_info holds additional information about the request.
+   * @param do_formatting whether or not to evaluate configured transformations; if false, returns
+   * original values instead.
+   */
+  virtual Http::HeaderTransforms requestHeaderTransforms(const StreamInfo::StreamInfo& stream_info,
+                                                         bool do_formatting = true) const PURE;
+
   /**
    * @return const HashPolicy* the optional hash policy for the route.
    */

diff --git a/source/common/http/async_client_impl.h b/source/common/http/async_client_impl.h
@@ -201,6 +201,10 @@ class AsyncStreamImpl : public AsyncClient::Stream,
     }
     void finalizeRequestHeaders(Http::RequestHeaderMap&, const StreamInfo::StreamInfo&,
                                 bool) const override {}
+    Http::HeaderTransforms requestHeaderTransforms(const StreamInfo::StreamInfo&,
+                                                   bool) const override {
+      return {};
+    }
     void finalizeResponseHeaders(Http::ResponseHeaderMap&,
                                  const StreamInfo::StreamInfo&) const override {}
     Http::HeaderTransforms responseHeaderTransforms(const StreamInfo::StreamInfo&,

diff --git a/source/common/router/config_impl.cc b/source/common/router/config_impl.cc
@@ -137,6 +137,24 @@ const envoy::config::route::v3::WeightedCluster::ClusterWeight& validateWeighted
   return cluster;
 }
 
+// Returns a vector of header parsers, sorted by specificity. The `specificity_ascend` parameter
+// specifies whether the returned parsers will be sorted from least specific to most specific
+// (global connection manager level header parser, virtual host level header parser and finally
+// route-level parser.) or the reverse.
+absl::InlinedVector<const HeaderParser*, 3>
+getHeaderParsers(const HeaderParser* global_route_config_header_parser,
+                 const HeaderParser* vhost_header_parser, const HeaderParser* route_header_parser,
+                 bool specificity_ascend) {
+  if (specificity_ascend) {
+    // Sorted from least to most specific: global connection manager level headers, virtual host
+    // level headers and finally route-level headers.
+    return {global_route_config_header_parser, vhost_header_parser, route_header_parser};
+  } else {
+    // Sorted from most to least specific.
+    return {route_header_parser, vhost_header_parser, global_route_config_header_parser};
+  }
+}
+
 } // namespace
 
 const std::string& OriginalConnectPort::key() {
@@ -645,17 +663,10 @@ const std::string& RouteEntryImplBase::clusterName() const { return cluster_name
 void RouteEntryImplBase::finalizeRequestHeaders(Http::RequestHeaderMap& headers,
                                                 const StreamInfo::StreamInfo& stream_info,
                                                 bool insert_envoy_original_path) const {
-  if (!vhost_.globalRouteConfig().mostSpecificHeaderMutationsWins()) {
-    // Append user-specified request headers from most to least specific: route-level headers,
-    // virtual host level headers and finally global connection manager level headers.
-    request_headers_parser_->evaluateHeaders(headers, stream_info);
-    vhost_.requestHeaderParser().evaluateHeaders(headers, stream_info);
-    vhost_.globalRouteConfig().requestHeaderParser().evaluateHeaders(headers, stream_info);
-  } else {
-    // Most specific mutations take precedence.
-    vhost_.globalRouteConfig().requestHeaderParser().evaluateHeaders(headers, stream_info);
-    vhost_.requestHeaderParser().evaluateHeaders(headers, stream_info);
-    request_headers_parser_->evaluateHeaders(headers, stream_info);
+  for (const HeaderParser* header_parser : getRequestHeaderParsers(
+           /*specificity_ascend=*/vhost_.globalRouteConfig().mostSpecificHeaderMutationsWins())) {
+    // Later evaluated header parser wins.
+    header_parser->evaluateHeaders(headers, stream_info);
   }
 
   // Restore the port if this was a CONNECT request.
@@ -698,48 +709,51 @@ void RouteEntryImplBase::finalizeRequestHeaders(Http::RequestHeaderMap& headers,
 
 void RouteEntryImplBase::finalizeResponseHeaders(Http::ResponseHeaderMap& headers,
                                                  const StreamInfo::StreamInfo& stream_info) const {
-  if (!vhost_.globalRouteConfig().mostSpecificHeaderMutationsWins()) {
-    // Append user-specified request headers from most to least specific: route-level headers,
-    // virtual host level headers and finally global connection manager level headers.
-    response_headers_parser_->evaluateHeaders(headers, stream_info);
-    vhost_.responseHeaderParser().evaluateHeaders(headers, stream_info);
-    vhost_.globalRouteConfig().responseHeaderParser().evaluateHeaders(headers, stream_info);
-  } else {
-    // Most specific mutations take precedence.
-    vhost_.globalRouteConfig().responseHeaderParser().evaluateHeaders(headers, stream_info);
-    vhost_.responseHeaderParser().evaluateHeaders(headers, stream_info);
-    response_headers_parser_->evaluateHeaders(headers, stream_info);
+  for (const HeaderParser* header_parser : getResponseHeaderParsers(
+           /*specificity_ascend=*/vhost_.globalRouteConfig().mostSpecificHeaderMutationsWins())) {
+    // Later evaluated header parser wins.
+    header_parser->evaluateHeaders(headers, stream_info);
   }
 }
 
 Http::HeaderTransforms
 RouteEntryImplBase::responseHeaderTransforms(const StreamInfo::StreamInfo& stream_info,
                                              bool do_formatting) const {
   Http::HeaderTransforms transforms;
-  if (!vhost_.globalRouteConfig().mostSpecificHeaderMutationsWins()) {
-    // Append user-specified request headers from most to least specific: route-level headers,
-    // virtual host level headers and finally global connection manager level headers.
-    mergeTransforms(transforms,
-                    response_headers_parser_->getHeaderTransforms(stream_info, do_formatting));
-    mergeTransforms(transforms,
-                    vhost_.responseHeaderParser().getHeaderTransforms(stream_info, do_formatting));
-    mergeTransforms(transforms,
-                    vhost_.globalRouteConfig().responseHeaderParser().getHeaderTransforms(
-                        stream_info, do_formatting));
-  } else {
-    // Most specific mutations (route-level) take precedence by being applied
-    // last: if a header is specified at all levels, the last one applied wins.
-    mergeTransforms(transforms,
-                    vhost_.globalRouteConfig().responseHeaderParser().getHeaderTransforms(
-                        stream_info, do_formatting));
-    mergeTransforms(transforms,
-                    vhost_.responseHeaderParser().getHeaderTransforms(stream_info, do_formatting));
-    mergeTransforms(transforms,
-                    response_headers_parser_->getHeaderTransforms(stream_info, do_formatting));
+  for (const HeaderParser* header_parser : getResponseHeaderParsers(
+           /*specificity_ascend=*/vhost_.globalRouteConfig().mostSpecificHeaderMutationsWins())) {
+    // Later evaluated header parser wins.
+    mergeTransforms(transforms, header_parser->getHeaderTransforms(stream_info, do_formatting));
+  }
+  return transforms;
+}
+
+Http::HeaderTransforms
+RouteEntryImplBase::requestHeaderTransforms(const StreamInfo::StreamInfo& stream_info,
+                                            bool do_formatting) const {
+  Http::HeaderTransforms transforms;
+  for (const HeaderParser* header_parser : getRequestHeaderParsers(
+           /*specificity_ascend=*/vhost_.globalRouteConfig().mostSpecificHeaderMutationsWins())) {
+    // Later evaluated header parser wins.
+    mergeTransforms(transforms, header_parser->getHeaderTransforms(stream_info, do_formatting));
   }
   return transforms;
 }
 
+absl::InlinedVector<const HeaderParser*, 3>
+RouteEntryImplBase::getRequestHeaderParsers(bool specificity_ascend) const {
+  return getHeaderParsers(&vhost_.globalRouteConfig().requestHeaderParser(),
+                          &vhost_.requestHeaderParser(), request_headers_parser_.get(),
+                          specificity_ascend);
+}
+
+absl::InlinedVector<const HeaderParser*, 3>
+RouteEntryImplBase::getResponseHeaderParsers(bool specificity_ascend) const {
+  return getHeaderParsers(&vhost_.globalRouteConfig().responseHeaderParser(),
+                          &vhost_.responseHeaderParser(), response_headers_parser_.get(),
+                          specificity_ascend);
+}
+
 absl::optional<RouteEntryImplBase::RuntimeData>
 RouteEntryImplBase::loadRuntimeData(const envoy::config::route::v3::RouteMatch& route_match) {
   absl::optional<RuntimeData> runtime;
@@ -1196,6 +1210,14 @@ RouteEntryImplBase::WeightedClusterEntry::WeightedClusterEntry(
   }
 }
 
+Http::HeaderTransforms RouteEntryImplBase::WeightedClusterEntry::requestHeaderTransforms(
+    const StreamInfo::StreamInfo& stream_info, bool do_formatting) const {
+  auto transforms = request_headers_parser_->getHeaderTransforms(stream_info, do_formatting);
+  mergeTransforms(transforms,
+                  DynamicRouteEntry::requestHeaderTransforms(stream_info, do_formatting));
+  return transforms;
+}
+
 Http::HeaderTransforms RouteEntryImplBase::WeightedClusterEntry::responseHeaderTransforms(
     const StreamInfo::StreamInfo& stream_info, bool do_formatting) const {
   auto transforms = response_headers_parser_->getHeaderTransforms(stream_info, do_formatting);

diff --git a/source/common/router/config_impl.h b/source/common/router/config_impl.h
@@ -531,6 +531,8 @@ class RouteEntryImplBase : public RouteEntry,
   void finalizeRequestHeaders(Http::RequestHeaderMap& headers,
                               const StreamInfo::StreamInfo& stream_info,
                               bool insert_envoy_original_path) const override;
+  Http::HeaderTransforms requestHeaderTransforms(const StreamInfo::StreamInfo& stream_info,
+                                                 bool do_formatting = true) const override;
   void finalizeResponseHeaders(Http::ResponseHeaderMap& headers,
                                const StreamInfo::StreamInfo& stream_info) const override;
   Http::HeaderTransforms responseHeaderTransforms(const StreamInfo::StreamInfo& stream_info,
@@ -672,6 +674,10 @@ class RouteEntryImplBase : public RouteEntry,
                                 bool insert_envoy_original_path) const override {
       return parent_->finalizeRequestHeaders(headers, stream_info, insert_envoy_original_path);
     }
+    Http::HeaderTransforms requestHeaderTransforms(const StreamInfo::StreamInfo& stream_info,
+                                                   bool do_formatting = true) const override {
+      return parent_->requestHeaderTransforms(stream_info, do_formatting);
+    }
     void finalizeResponseHeaders(Http::ResponseHeaderMap& headers,
                                  const StreamInfo::StreamInfo& stream_info) const override {
       return parent_->finalizeResponseHeaders(headers, stream_info);
@@ -810,6 +816,8 @@ class RouteEntryImplBase : public RouteEntry,
       }
       DynamicRouteEntry::finalizeRequestHeaders(headers, stream_info, insert_envoy_original_path);
     }
+    Http::HeaderTransforms requestHeaderTransforms(const StreamInfo::StreamInfo& stream_info,
+                                                   bool do_formatting = true) const override;
     void finalizeResponseHeaders(Http::ResponseHeaderMap& headers,
                                  const StreamInfo::StreamInfo& stream_info) const override {
       response_headers_parser_->evaluateHeaders(headers, stream_info);
@@ -844,6 +852,28 @@ class RouteEntryImplBase : public RouteEntry,
 
   using WeightedClusterEntrySharedPtr = std::shared_ptr<WeightedClusterEntry>;
 
+  /**
+   * Returns a vector of request header parsers which applied or will apply header transformations
+   * to the request in this route.
+   * @param specificity_ascend specifies whether the returned parsers will be sorted from least
+   *        specific to most specific (global connection manager level header parser, virtual host
+   *        level header parser and finally route-level parser.) or the reverse.
+   * @return a vector of request header parsers.
+   */
+  absl::InlinedVector<const HeaderParser*, 3>
+  getRequestHeaderParsers(bool specificity_ascend) const;
+
+  /**
+   * Returns a vector of response header parsers which applied or will apply header transformations
+   * to the response in this route.
+   * @param specificity_ascend specifies whether the returned parsers will be sorted from least
+   *        specific to most specific (global connection manager level header parser, virtual host
+   *        level header parser and finally route-level parser.) or the reverse.
+   * @return a vector of request header parsers.
+   */
+  absl::InlinedVector<const HeaderParser*, 3>
+  getResponseHeaderParsers(bool specificity_ascend) const;
+
   absl::optional<RuntimeData> loadRuntimeData(const envoy::config::route::v3::RouteMatch& route);
 
   static std::multimap<std::string, std::string>

diff --git a/source/common/router/delegating_route_impl.cc b/source/common/router/delegating_route_impl.cc
@@ -50,6 +50,12 @@ void DelegatingRouteEntry::finalizeRequestHeaders(Http::RequestHeaderMap& header
                                                            insert_envoy_original_path);
 }
 
+Http::HeaderTransforms
+DelegatingRouteEntry::requestHeaderTransforms(const StreamInfo::StreamInfo& stream_info,
+                                              bool do_formatting) const {
+  return base_route_->routeEntry()->requestHeaderTransforms(stream_info, do_formatting);
+}
+
 const Http::HashPolicy* DelegatingRouteEntry::hashPolicy() const {
   return base_route_->routeEntry()->hashPolicy();
 }

diff --git a/source/common/router/delegating_route_impl.h b/source/common/router/delegating_route_impl.h
@@ -76,6 +76,9 @@ class DelegatingRouteEntry : public Router::RouteEntry {
   void finalizeRequestHeaders(Http::RequestHeaderMap& headers,
                               const StreamInfo::StreamInfo& stream_info,
                               bool insert_envoy_original_path) const override;
+  Http::HeaderTransforms requestHeaderTransforms(const StreamInfo::StreamInfo& stream_info,
+                                                 bool do_formatting = true) const override;
+
   const Http::HashPolicy* hashPolicy() const override;
   const HedgePolicy& hedgePolicy() const override;
   Upstream::ResourcePriority priority() const override;

diff --git a/source/docs/response_header_transforms.md → source/docs/header_transforms.md b/source/docs/response_header_transforms.md → source/docs/header_transforms.md
@@ -1,15 +1,17 @@
-## `ResponseEntry::responseHeaderTransforms` API
+## `RouteEntry::requestHeaderTransforms` and `ResponseEntry::responseHeaderTransforms` APIs
 
 ### Overview
 
-`ResponseEntry::responseHeaderTransforms` allows filters to obtain response
-header transformations that would be applied by
-`ResponseEntry::finalizeResponseHeaders`.
+`RouteEntry::requestHeaderTransforms`
+and `ResponseEntry::responseHeaderTransforms` allows filters to obtain request
+and response header transformations that would be applied by
+`RouteEntry::finalizeRequestHeaders`
+and `ResponseEntry::finalizeResponseHeaders` respectively.
 
 If you do not have full knowledge that there will be no further route
-modifications later in the filter chain, you should not use this API.
+modifications later in the filter chain, you should not use these APIs.
 
-### Usage
+### Example usage
 
 To obtain the response header transformations at request time: