Allow specified UDP cmsg to be saved to QuicReceivedPacket (#35382)

Commit Message: Allow specified UDP cmsg to be saved to
QuicReceivedPacket
Additional Description: This can be accessed via
QuicListenerFilter::onFirstPacketReceived.
Risk Level: Low
Testing: Integration test
Docs Changes: N/A
Release Notes: added

---------

Signed-off-by: Paul Sohn <paulsohn@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ bd5bec9abb537b3d462ed4e74bb5ea4bf1844655

envoy/config/core/v3/socket_cmsg_headers.proto

@@ -0,0 +1,28 @@
+syntax = "proto3";
+
+package envoy.config.core.v3;
+
+import "google/protobuf/wrappers.proto";
+
+import "udpa/annotations/status.proto";
+
+option java_package = "io.envoyproxy.envoy.config.core.v3";
+option java_outer_classname = "SocketCmsgHeadersProto";
+option java_multiple_files = true;
+option go_package = "github.com/envoyproxy/go-control-plane/envoy/config/core/v3;corev3";
+option (udpa.annotations.file_status).package_version_status = ACTIVE;
+
+// [#protodoc-title: Socket CMSG headers]
+
+// Configuration for socket cmsg headers.
+// See `:ref:CMSG <https://man7.org/linux/man-pages/man3/cmsg.3.html>`_ for further information.
+message SocketCmsgHeaders {
+  // cmsg level. Default is unset.
+  google.protobuf.UInt32Value level = 1;
+
+  // cmsg type. Default is unset.
+  google.protobuf.UInt32Value type = 2;
+
+  // Expected size of cmsg value. Default is zero.
+  uint32 expected_size = 3;
+}

envoy/config/listener/v3/quic_config.proto

@@ -5,6 +5,7 @@ package envoy.config.listener.v3;
 import "envoy/config/core/v3/base.proto";
 import "envoy/config/core/v3/extension.proto";
 import "envoy/config/core/v3/protocol.proto";
+import "envoy/config/core/v3/socket_cmsg_headers.proto";
 
 import "google/protobuf/duration.proto";
 import "google/protobuf/wrappers.proto";
@@ -24,7 +25,7 @@ option (udpa.annotations.file_status).package_version_status = ACTIVE;
 // [#protodoc-title: QUIC listener config]
 
 // Configuration specific to the UDP QUIC listener.
-// [#next-free-field: 12]
+// [#next-free-field: 13]
 message QuicProtocolOptions {
   option (udpa.annotations.versioning).previous_message_type =
       "envoy.api.v2.listener.QuicProtocolOptions";
@@ -86,4 +87,11 @@ message QuicProtocolOptions {
   // If not specified, no debug visitor will be attached to connections.
   // [#extension-category: envoy.quic.connection_debug_visitor]
   core.v3.TypedExtensionConfig connection_debug_visitor_config = 11;
+
+  // Configure a type of UDP cmsg to pass to listener filters via QuicReceivedPacket.
+  // Both level and type must be specified for cmsg to be saved.
+  // Cmsg may be truncated or omitted if expected size is not set.
+  // If not specified, no cmsg will be saved to QuicReceivedPacket.
+  repeated core.v3.SocketCmsgHeaders save_cmsg_config = 12
+      [(validate.rules).repeated = {max_items: 1}];
 }