Engine API PR 498 (clarify payloadAttributes checks) (#8982)

Implements ethereum/execution-apis#498

Author: yperbasis

turbo/engineapi/engine_server.go

@@ -452,25 +452,20 @@ func (s *EngineServer) forkchoiceUpdated(ctx context.Context, forkchoiceState *e
 	}
 
 	if payloadAttributes != nil {
+		if version < clparams.DenebVersion && payloadAttributes.ParentBeaconBlockRoot != nil {
+			return nil, &engine_helpers.InvalidPayloadAttributesErr // Unexpected Beacon Root
+		}
+		if version >= clparams.DenebVersion && payloadAttributes.ParentBeaconBlockRoot == nil {
+			return nil, &engine_helpers.InvalidPayloadAttributesErr // Beacon Root missing
+		}
+
 		timestamp := uint64(payloadAttributes.Timestamp)
 		if !s.config.IsCancun(timestamp) && version >= clparams.DenebVersion { // V3 before cancun
-			if payloadAttributes.ParentBeaconBlockRoot == nil {
-				return nil, &rpc.InvalidParamsError{Message: "Beacon Root missing"}
-			}
 			return nil, &rpc.UnsupportedForkError{Message: "Unsupported fork"}
 		}
 		if s.config.IsCancun(timestamp) && version < clparams.DenebVersion { // Not V3 after cancun
-			if payloadAttributes.ParentBeaconBlockRoot != nil {
-				return nil, &rpc.InvalidParamsError{Message: "Unexpected Beacon Root"}
-			}
 			return nil, &rpc.UnsupportedForkError{Message: "Unsupported fork"}
 		}
-
-		if s.config.IsCancun(timestamp) && version >= clparams.DenebVersion {
-			if payloadAttributes.ParentBeaconBlockRoot == nil {
-				return nil, &rpc.InvalidParamsError{Message: "Beacon Root missing"}
-			}
-		}
 	}
 
 	// No need for payload building
@@ -484,19 +479,6 @@ func (s *EngineServer) forkchoiceUpdated(ctx context.Context, forkchoiceState *e
 
 	headHeader := s.chainRW.GetHeaderByHash(forkchoiceState.HeadHash)
 
-	if headHeader.Hash() != forkchoiceState.HeadHash {
-		// Per Item 2 of https://github.com/ethereum/execution-apis/blob/v1.0.0-alpha.9/src/engine/specification.md#specification-1:
-		// Client software MAY skip an update of the forkchoice state and
-		// MUST NOT begin a payload build process if forkchoiceState.headBlockHash doesn't reference a leaf of the block tree.
-		// That is, the block referenced by forkchoiceState.headBlockHash is neither the head of the canonical chain nor a block at the tip of any other chain.
-		// In the case of such an event, client software MUST return
-		// {payloadStatus: {status: VALID, latestValidHash: forkchoiceState.headBlockHash, validationError: null}, payloadId: null}.
-
-		s.logger.Warn("Skipping payload building because forkchoiceState.headBlockHash is not the head of the canonical chain",
-			"forkChoice.HeadBlockHash", forkchoiceState.HeadHash, "headHeader.Hash", headHeader.Hash())
-		return &engine_types.ForkChoiceUpdatedResponse{PayloadStatus: status}, nil
-	}
-
 	timestamp := uint64(payloadAttributes.Timestamp)
 	if headHeader.Time >= timestamp {
 		return nil, &engine_helpers.InvalidPayloadAttributesErr