From 64a333a0707547589efa8356f7b69cd6c13dbdc9 Mon Sep 17 00:00:00 2001
From: Zsolt Felfoldi <zsfelfoldi@gmail.com>
Date: Thu, 11 Apr 2024 16:27:51 +0200
Subject: [PATCH] beacon/light/api: include canonical and finalized flags in
 header response

---
 beacon/light/api/api_server.go |  4 +++-
 beacon/light/api/light_api.go  | 17 ++++++++++-------
 beacon/light/sync/types.go     |  6 +++++-
 3 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/beacon/light/api/api_server.go b/beacon/light/api/api_server.go
index da044f4b2d..76e2b71c98 100755
--- a/beacon/light/api/api_server.go
+++ b/beacon/light/api/api_server.go
@@ -73,8 +73,10 @@ func (s *ApiServer) SendRequest(id request.ID, req request.Request) {
 			r.Updates, r.Committees, err = s.api.GetBestUpdatesAndCommittees(data.FirstPeriod, data.Count)
 			resp = r
 		case sync.ReqHeader:
+			var r sync.RespHeader
 			log.Debug("Beacon API: requesting header", "reqid", id, "hash", common.Hash(data))
-			resp, err = s.api.GetHeader(common.Hash(data))
+			r.Header, r.Canonical, r.Finalized, err = s.api.GetHeader(common.Hash(data))
+			resp = r
 		case sync.ReqCheckpointData:
 			log.Debug("Beacon API: requesting checkpoint data", "reqid", id, "hash", common.Hash(data))
 			resp, err = s.api.GetCheckpointData(common.Hash(data))
diff --git a/beacon/light/api/light_api.go b/beacon/light/api/light_api.go
index ceb4261c3c..6892407caf 100755
--- a/beacon/light/api/light_api.go
+++ b/beacon/light/api/light_api.go
@@ -291,7 +291,9 @@ func decodeFinalityUpdate(enc []byte) (types.FinalityUpdate, error) {
 
 // GetHeader fetches and validates the beacon header with the given blockRoot.
 // If blockRoot is null hash then the latest head header is fetched.
-func (api *BeaconLightApi) GetHeader(blockRoot common.Hash) (types.Header, error) {
+// The values of the canonical and finalized flags are also returned. Note that
+// these flags are not validated.
+func (api *BeaconLightApi) GetHeader(blockRoot common.Hash) (types.Header, bool, bool, error) {
 	var blockId string
 	if blockRoot == (common.Hash{}) {
 		blockId = "head"
@@ -300,11 +302,12 @@ func (api *BeaconLightApi) GetHeader(blockRoot common.Hash) (types.Header, error
 	}
 	resp, err := api.httpGetf("/eth/v1/beacon/headers/%s", blockId)
 	if err != nil {
-		return types.Header{}, err
+		return types.Header{}, false, false, err
 	}
 
 	var data struct {
-		Data struct {
+		Finalized bool `json:"finalized"`
+		Data      struct {
 			Root      common.Hash `json:"root"`
 			Canonical bool        `json:"canonical"`
 			Header    struct {
@@ -314,16 +317,16 @@ func (api *BeaconLightApi) GetHeader(blockRoot common.Hash) (types.Header, error
 		} `json:"data"`
 	}
 	if err := json.Unmarshal(resp, &data); err != nil {
-		return types.Header{}, err
+		return types.Header{}, false, false, err
 	}
 	header := data.Data.Header.Message
 	if blockRoot == (common.Hash{}) {
 		blockRoot = data.Data.Root
 	}
 	if header.Hash() != blockRoot {
-		return types.Header{}, errors.New("retrieved beacon header root does not match")
+		return types.Header{}, false, false, errors.New("retrieved beacon header root does not match")
 	}
-	return header, nil
+	return header, data.Data.Canonical, data.Finalized, nil
 }
 
 // GetCheckpointData fetches and validates bootstrap data belonging to the given checkpoint.
@@ -446,7 +449,7 @@ func (api *BeaconLightApi) StartHeadListener(listener HeadEventListener) func()
 		defer wg.Done()
 
 		// Request initial data.
-		if head, err := api.GetHeader(common.Hash{}); err == nil {
+		if head, _, _, err := api.GetHeader(common.Hash{}); err == nil {
 			listener.OnNewHead(head.Slot, head.Hash())
 		}
 		if signedHead, err := api.GetOptimisticHeadUpdate(); err == nil {
diff --git a/beacon/light/sync/types.go b/beacon/light/sync/types.go
index 6449ae842d..8aa4c95f46 100644
--- a/beacon/light/sync/types.go
+++ b/beacon/light/sync/types.go
@@ -36,7 +36,11 @@ type (
 		Updates    []*types.LightClientUpdate
 		Committees []*types.SerializedSyncCommittee
 	}
-	ReqHeader         common.Hash
+	ReqHeader  common.Hash
+	RespHeader struct {
+		Header               types.Header
+		Canonical, Finalized bool
+	}
 	ReqCheckpointData common.Hash
 	ReqBeaconBlock    common.Hash
 )