API definition for scrubbing request headers sending from ext_proc filter to ext_proc server (#27333)

API definition for scrubbing request headers sending from ext_proc filter to ext_proc server

Signed-off-by: Yanjun Xiang <yanjunxiang@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 7d1b1d0040054093575dcda742099be9641e3a64

envoy/extensions/filters/http/ext_proc/v3/BUILD

@@ -8,6 +8,7 @@ api_proto_package(
     deps = [
         "//envoy/config/common/mutation_rules/v3:pkg",
         "//envoy/config/core/v3:pkg",
+        "//envoy/type/matcher/v3:pkg",
         "@com_github_cncf_udpa//udpa/annotations:pkg",
         "@com_github_cncf_udpa//xds/annotations/v3:pkg",
     ],

envoy/extensions/filters/http/ext_proc/v3/ext_proc.proto

@@ -5,6 +5,7 @@ package envoy.extensions.filters.http.ext_proc.v3;
 import "envoy/config/common/mutation_rules/v3/mutation_rules.proto";
 import "envoy/config/core/v3/grpc_service.proto";
 import "envoy/extensions/filters/http/ext_proc/v3/processing_mode.proto";
+import "envoy/type/matcher/v3/string.proto";
 
 import "google/protobuf/duration.proto";
 
@@ -95,7 +96,7 @@ option (xds.annotations.v3.file_status).work_in_progress = true;
 // messages, and the server must reply with
 // :ref:`ProcessingResponse <envoy_v3_api_msg_service.ext_proc.v3.ProcessingResponse>`.
 
-// [#next-free-field: 12]
+// [#next-free-field: 13]
 message ExternalProcessor {
   // Configuration for the gRPC service that the filter will communicate with.
   // The filter supports both the "Envoy" and "Google" gRPC clients.
@@ -180,6 +181,17 @@ message ExternalProcessor {
   // :ref:`clear_route_cache <envoy_v3_api_field_service.ext_proc.v3.CommonResponse.clear_route_cache>`
   // field is set in an external processor response.
   bool disable_clear_route_cache = 11;
+
+  // [#not-implemented-hide:]
+  // Allow headers matching the ``forward_rules`` to be forwarded to the external processing server.
+  // If not set, all headers are forwarded to the external processing server.
+  HeaderForwardingRules forward_rules = 12;
+}
+
+// The HeaderForwardingRules structure specifies what headers are
+// allowed to be forwarded to the external processing server.
+message HeaderForwardingRules {
+  type.matcher.v3.ListStringMatcher allowed_headers = 1;
 }
 
 // Extra settings that may be added to per-route configuration for a