internal/ethapi: fix merge transition in eth_simulate (#32616)

This PR fixes the fork detection of `eth_simulateV1`, particularly
for networks that are post-merge since genesis, like Hoodi.

consensus/beacon/consensus.go

@@ -71,16 +71,6 @@ func New(ethone consensus.Engine) *Beacon {
 	return &Beacon{ethone: ethone}
 }
 
-// isPostMerge reports whether the given block number is assumed to be post-merge.
-// Here we check the MergeNetsplitBlock to allow configuring networks with a PoW or
-// PoA chain for unit testing purposes.
-func isPostMerge(config *params.ChainConfig, blockNum uint64, timestamp uint64) bool {
-	mergedAtGenesis := config.TerminalTotalDifficulty != nil && config.TerminalTotalDifficulty.Sign() == 0
-	return mergedAtGenesis ||
-		config.MergeNetsplitBlock != nil && blockNum >= config.MergeNetsplitBlock.Uint64() ||
-		config.ShanghaiTime != nil && timestamp >= *config.ShanghaiTime
-}
-
 // Author implements consensus.Engine, returning the verified author of the block.
 func (beacon *Beacon) Author(header *types.Header) (common.Address, error) {
 	if !beacon.IsPoSHeader(header) {
@@ -328,7 +318,7 @@ func (beacon *Beacon) verifyHeaders(chain consensus.ChainHeaderReader, headers [
 // Prepare implements consensus.Engine, initializing the difficulty field of a
 // header to conform to the beacon protocol. The changes are done inline.
 func (beacon *Beacon) Prepare(chain consensus.ChainHeaderReader, header *types.Header) error {
-	if !isPostMerge(chain.Config(), header.Number.Uint64(), header.Time) {
+	if !chain.Config().IsPostMerge(header.Number.Uint64(), header.Time) {
 		return beacon.ethone.Prepare(chain, header)
 	}
 	header.Difficulty = beaconDifficulty
@@ -442,7 +432,7 @@ func (beacon *Beacon) SealHash(header *types.Header) common.Hash {
 // the difficulty that a new block should have when created at time
 // given the parent block's time and difficulty.
 func (beacon *Beacon) CalcDifficulty(chain consensus.ChainHeaderReader, time uint64, parent *types.Header) *big.Int {
-	if !isPostMerge(chain.Config(), parent.Number.Uint64()+1, time) {
+	if !chain.Config().IsPostMerge(parent.Number.Uint64()+1, time) {
 		return beacon.ethone.CalcDifficulty(chain, time, parent)
 	}
 	return beaconDifficulty

internal/ethapi/simulate.go

@@ -474,22 +474,30 @@ func (sim *simulator) makeHeaders(blocks []simBlock) ([]*types.Header, error) {
 		overrides := block.BlockOverrides
 
 		var withdrawalsHash *common.Hash
-		if sim.chainConfig.IsShanghai(overrides.Number.ToInt(), (uint64)(*overrides.Time)) {
+		number := overrides.Number.ToInt()
+		timestamp := (uint64)(*overrides.Time)
+		if sim.chainConfig.IsShanghai(number, timestamp) {
 			withdrawalsHash = &types.EmptyWithdrawalsHash
 		}
 		var parentBeaconRoot *common.Hash
-		if sim.chainConfig.IsCancun(overrides.Number.ToInt(), (uint64)(*overrides.Time)) {
+		if sim.chainConfig.IsCancun(number, timestamp) {
 			parentBeaconRoot = &common.Hash{}
 			if overrides.BeaconRoot != nil {
 				parentBeaconRoot = overrides.BeaconRoot
 			}
 		}
+		// Set difficulty to zero if the given block is post-merge. Without this, all post-merge hardforks would remain inactive.
+		// For example, calling eth_simulateV1(..., blockParameter: 0x0) on hoodi network will cause all blocks to have a difficulty of 1 and be treated as pre-merge.
+		difficulty := header.Difficulty
+		if sim.chainConfig.IsPostMerge(number.Uint64(), timestamp) {
+			difficulty = big.NewInt(0)
+		}
 		header = overrides.MakeHeader(&types.Header{
 			UncleHash:        types.EmptyUncleHash,
 			ReceiptHash:      types.EmptyReceiptsHash,
 			TxHash:           types.EmptyTxsHash,
 			Coinbase:         header.Coinbase,
-			Difficulty:       header.Difficulty,
+			Difficulty:       difficulty,
 			GasLimit:         header.GasLimit,
 			WithdrawalsHash:  withdrawalsHash,
 			ParentBeaconRoot: parentBeaconRoot,

params/config.go

@@ -678,6 +678,16 @@ func (c *ChainConfig) IsTerminalPoWBlock(parentTotalDiff *big.Int, totalDiff *bi
 	return parentTotalDiff.Cmp(c.TerminalTotalDifficulty) < 0 && totalDiff.Cmp(c.TerminalTotalDifficulty) >= 0
 }
 
+// IsPostMerge reports whether the given block number is assumed to be post-merge.
+// Here we check the MergeNetsplitBlock to allow configuring networks with a PoW or
+// PoA chain for unit testing purposes.
+func (c *ChainConfig) IsPostMerge(blockNum uint64, timestamp uint64) bool {
+	mergedAtGenesis := c.TerminalTotalDifficulty != nil && c.TerminalTotalDifficulty.Sign() == 0
+	return mergedAtGenesis ||
+		c.MergeNetsplitBlock != nil && blockNum >= c.MergeNetsplitBlock.Uint64() ||
+		c.ShanghaiTime != nil && timestamp >= *c.ShanghaiTime
+}
+
 // IsShanghai returns whether time is either equal to the Shanghai fork time or greater.
 func (c *ChainConfig) IsShanghai(num *big.Int, time uint64) bool {
 	return c.IsLondon(num) && isTimestampForked(c.ShanghaiTime, time)