Config: Introduce check for isthmus hardfork

and update checks for l2 withdrawal root to be gated on Isthmus instead
of Holocene

beacon/engine/types.go

@@ -88,7 +88,7 @@ type ExecutableData struct {
 	BlobGasUsed   *uint64             `json:"blobGasUsed"`
 	ExcessBlobGas *uint64             `json:"excessBlobGas"`
 
-	// OP-Stack Holocene specific field:
+	// OP-Stack Isthmus specific field:
 	// instead of computing the root from a withdrawals list, set it directly.
 	// The "withdrawals" list attribute must be non-nil but empty.
 	WithdrawalsRoot *common.Hash `json:"withdrawalsRoot,omitempty"`

consensus/beacon/consensus.go

@@ -403,9 +403,9 @@ func (beacon *Beacon) FinalizeAndAssemble(chain consensus.ChainHeaderReader, hea
 	// Assign the final state root to header.
 	header.Root = state.IntermediateRoot(true)
 
-	if chain.Config().IsOptimismHolocene(header.Time) {
-		if body.Withdrawals == nil || len(body.Withdrawals) > 0 { // We verify nil/empty withdrawals in the CL pre-holocene
-			return nil, fmt.Errorf("expected non-nil empty withdrawals operation list in Holocene, but got: %v", body.Withdrawals)
+	if chain.Config().IsOptimismIsthmus(header.Time) {
+		if body.Withdrawals == nil || len(body.Withdrawals) > 0 { // We verify nil/empty withdrawals in the CL pre-isthmus
+			return nil, fmt.Errorf("expected non-nil empty withdrawals operation list in Isthmus, but got: %v", body.Withdrawals)
 		}
 		// State-root has just been computed, we can get an accurate storage-root now.
 		h := state.GetStorageRoot(params.OptimismL2ToL1MessagePasser)

core/block_validator.go

@@ -75,7 +75,7 @@ func (v *BlockValidator) ValidateBody(block *types.Block) error {
 		if block.Withdrawals() == nil {
 			return errors.New("missing withdrawals in block body")
 		}
-		if v.config.IsOptimismHolocene(header.Time) {
+		if v.config.IsOptimismIsthmus(header.Time) {
 			if len(block.Withdrawals()) > 0 {
 				return errors.New("no withdrawal block-operations allowed, withdrawalsRoot is set to storage root")
 			}
@@ -152,9 +152,9 @@ func (v *BlockValidator) ValidateState(block *types.Block, statedb *state.StateD
 	if root := statedb.IntermediateRoot(v.config.IsEIP158(header.Number)); header.Root != root {
 		return fmt.Errorf("invalid merkle root (remote: %x local: %x) dberr: %w", header.Root, root, statedb.Error())
 	}
-	if v.config.IsOptimismHolocene(block.Time()) {
+	if v.config.IsOptimismIsthmus(block.Time()) {
 		if header.WithdrawalsHash == nil {
-			return errors.New("expected withdrawals root in OP-Stack post-Holocene block header")
+			return errors.New("expected withdrawals root in OP-Stack post-Isthmus block header")
 		}
 		// Validate the withdrawals root against the L2 withdrawals storage, similar to how the StateRoot is verified.
 		if root := statedb.GetStorageRoot(params.OptimismL2ToL1MessagePasser); *header.WithdrawalsHash != root {

eth/downloader/queue.go

@@ -122,7 +122,7 @@ func (f *fetchResult) Done(kind uint) bool {
 }
 
 type OPStackChainConfig interface {
-	IsOptimismHolocene(time uint64) bool
+	IsOptimismIsthmus(time uint64) bool
 }
 
 // queue represents hashes that are either need fetching or are being fetched
@@ -814,8 +814,8 @@ func (q *queue) DeliverBodies(id string, txLists [][]*types.Transaction, txListH
 			if withdrawalLists[index] == nil {
 				return errInvalidBody
 			}
-			if q.opConfig != nil && q.opConfig.IsOptimismHolocene(header.Time) {
-				// If Holocene, we expect an empty list of withdrawal operations,
+			if q.opConfig != nil && q.opConfig.IsOptimismIsthmus(header.Time) {
+				// If Isthmus, we expect an empty list of withdrawal operations,
 				// but the WithdrawalsHash in the header is used for the withdrawals state storage-root.
 				if withdrawalListHashes[index] != types.EmptyWithdrawalsHash {
 					return errInvalidBody

params/config.go

@@ -378,6 +378,7 @@ type ChainConfig struct {
 	FjordTime    *uint64 `json:"fjordTime,omitempty"`    // Fjord switch time (nil = no fork, 0 = already on Optimism Fjord)
 	GraniteTime  *uint64 `json:"graniteTime,omitempty"`  // Granite switch time (nil = no fork, 0 = already on Optimism Granite)
 	HoloceneTime *uint64 `json:"holoceneTime,omitempty"` // Holocene switch time (nil = no fork, 0 = already on Optimism Holocene)
+	IsthmusTime  *uint64 `json:"isthmusTime,omitempty"`  // Isthmus switch time (nil = no fork, 0 = already on Optimism Isthmus)
 
 	InteropTime *uint64 `json:"interopTime,omitempty"` // Interop switch time (nil = no fork, 0 = already on optimism interop)
 
@@ -680,6 +681,10 @@ func (c *ChainConfig) IsHolocene(time uint64) bool {
 	return isTimestampForked(c.HoloceneTime, time)
 }
 
+func (c *ChainConfig) IsIsthmus(time uint64) bool {
+	return isTimestampForked(c.IsthmusTime, time)
+}
+
 func (c *ChainConfig) IsInterop(time uint64) bool {
 	return isTimestampForked(c.InteropTime, time)
 }
@@ -718,6 +723,10 @@ func (c *ChainConfig) IsOptimismHolocene(time uint64) bool {
 	return c.IsOptimism() && c.IsHolocene(time)
 }
 
+func (c *ChainConfig) IsOptimismIsthmus(time uint64) bool {
+	return c.IsOptimism() && c.IsIsthmus(time)
+}
+
 // IsOptimismPreBedrock returns true iff this is an optimism node & bedrock is not yet active
 func (c *ChainConfig) IsOptimismPreBedrock(num *big.Int) bool {
 	return c.IsOptimism() && !c.IsBedrock(num)