feat: ensure requests array empty post-Isthmus (#478)

* feat: ensure requests array empty post-Isthmus

* Add IsIsthmus to block config

* Remove unnecessary isthmus check

* Reword fix

---------

Co-authored-by: refcell <[email protected]>

Author: meyer9

beacon/engine/types.go

@@ -297,10 +297,16 @@ func ExecutableDataToBlockNoHash(data ExecutableData, versionedHashes []common.H
 		withdrawalsRoot = &h
 	}
 
+	isthmusEnabled := bType.IsIsthmus(data.Timestamp)
 	var requestsHash *common.Hash
 	if requests != nil {
+		if isthmusEnabled && len(requests) > 0 {
+			return nil, fmt.Errorf("requests should be empty for Isthmus blocks")
+		}
 		h := types.CalcRequestsHash(requests)
 		requestsHash = &h
+	} else if isthmusEnabled {
+		return nil, fmt.Errorf("requests must be an empty array for Isthmus blocks")
 	}
 
 	header := &types.Header{

core/types/block.go

@@ -251,6 +251,7 @@ type extblock struct {
 
 type BlockType interface {
 	HasOptimismWithdrawalsRoot(blkTime uint64) bool
+	IsIsthmus(blkTime uint64) bool
 }
 
 // NewBlock creates a new block. The input data is copied, changes to header and to the

core/types/block_config.go

@@ -1,14 +1,18 @@
 package types
 
 type BlockConfig struct {
-	CustomWithdrawalsRoot bool
+	IsIsthmusEnabled bool
 }
 
 func (bc *BlockConfig) HasOptimismWithdrawalsRoot(blockTime uint64) bool {
-	return bc.CustomWithdrawalsRoot
+	return bc.IsIsthmusEnabled
+}
+
+func (bc *BlockConfig) IsIsthmus(blockTime uint64) bool {
+	return bc.IsIsthmusEnabled
 }
 
 var (
-	DefaultBlockConfig = &BlockConfig{CustomWithdrawalsRoot: false}
-	IsthmusBlockConfig = &BlockConfig{CustomWithdrawalsRoot: true}
+	DefaultBlockConfig = &BlockConfig{IsIsthmusEnabled: false}
+	IsthmusBlockConfig = &BlockConfig{IsIsthmusEnabled: true}
 )