core/forkid: correctly compute forkid when timestamp fork is activated in genesis (#27895)

This changes the forkID calculation to ignore time-based forks that occurred before the
genesis block. It's supposed to be done this way because the spec says:

> If a chain is configured to start with a non-Frontier ruleset already in its genesis, that is NOT considered a fork.

core/forkid/forkid.go

@@ -73,9 +73,9 @@ type ID struct {
 type Filter func(id ID) error
 
 // NewID calculates the Ethereum fork ID from the chain config, genesis hash, head and time.
-func NewID(config *params.ChainConfig, genesis common.Hash, head, time uint64) ID {
+func NewID(config *params.ChainConfig, genesis *types.Block, head, time uint64) ID {
 	// Calculate the starting checksum from the genesis hash
-	hash := crc32.ChecksumIEEE(genesis[:])
+	hash := crc32.ChecksumIEEE(genesis.Hash().Bytes())
 
 	// Calculate the current fork checksum and the next fork block
 	forksByBlock, forksByTime := gatherForks(config)
@@ -88,6 +88,10 @@ func NewID(config *params.ChainConfig, genesis common.Hash, head, time uint64) I
 		return ID{Hash: checksumToBytes(hash), Next: fork}
 	}
 	for _, fork := range forksByTime {
+		if fork <= genesis.Time() {
+			// Fork active in genesis, skip in forkid calculation
+			continue
+		}
 		if fork <= time {
 			// Fork already passed, checksum the previous hash and fork timestamp
 			hash = checksumUpdate(hash, fork)
@@ -104,7 +108,7 @@ func NewIDWithChain(chain Blockchain) ID {
 
 	return NewID(
 		chain.Config(),
-		chain.Genesis().Hash(),
+		chain.Genesis(),
 		head.Number.Uint64(),
 		head.Time,
 	)

core/forkid/forkid_test.go

@@ -18,10 +18,14 @@ package forkid
 
 import (
 	"bytes"
+	"hash/crc32"
 	"math"
+	"math/big"
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
 )
@@ -36,13 +40,13 @@ func TestCreation(t *testing.T) {
 	}
 	tests := []struct {
 		config  *params.ChainConfig
-		genesis common.Hash
+		genesis *types.Block
 		cases   []testcase
 	}{
 		// Mainnet test cases
 		{
 			params.MainnetChainConfig,
-			params.MainnetGenesisHash,
+			core.DefaultGenesisBlock().ToBlock(),
 			[]testcase{
 				{0, 0, ID{Hash: checksumToBytes(0xfc64ec04), Next: 1150000}},                    // Unsynced
 				{1149999, 0, ID{Hash: checksumToBytes(0xfc64ec04), Next: 1150000}},              // Last Frontier block
@@ -77,7 +81,7 @@ func TestCreation(t *testing.T) {
 		// Goerli test cases
 		{
 			params.GoerliChainConfig,
-			params.GoerliGenesisHash,
+			core.DefaultGoerliGenesisBlock().ToBlock(),
 			[]testcase{
 				{0, 0, ID{Hash: checksumToBytes(0xa3f5ab08), Next: 1561651}},                   // Unsynced, last Frontier, Homestead, Tangerine, Spurious, Byzantium, Constantinople and first Petersburg block
 				{1561650, 0, ID{Hash: checksumToBytes(0xa3f5ab08), Next: 1561651}},             // Last Petersburg block
@@ -94,7 +98,7 @@ func TestCreation(t *testing.T) {
 		// Sepolia test cases
 		{
 			params.SepoliaChainConfig,
-			params.SepoliaGenesisHash,
+			core.DefaultSepoliaGenesisBlock().ToBlock(),
 			[]testcase{
 				{0, 0, ID{Hash: checksumToBytes(0xfe3366e7), Next: 1735371}},                   // Unsynced, last Frontier, Homestead, Tangerine, Spurious, Byzantium, Constantinople, Petersburg, Istanbul, Berlin and first London block
 				{1735370, 0, ID{Hash: checksumToBytes(0xfe3366e7), Next: 1735371}},             // Last London block
@@ -382,3 +386,55 @@ func TestEncoding(t *testing.T) {
 		}
 	}
 }
+
+// Tests that time-based forks which are active at genesis are not included in
+// forkid hash.
+func TestTimeBasedForkInGenesis(t *testing.T) {
+	var (
+		time       = uint64(1690475657)
+		genesis    = types.NewBlockWithHeader(&types.Header{Time: time})
+		forkidHash = checksumToBytes(crc32.ChecksumIEEE(genesis.Hash().Bytes()))
+		config     = func(shanghai, cancun uint64) *params.ChainConfig {
+			return &params.ChainConfig{
+				ChainID:                       big.NewInt(1337),
+				HomesteadBlock:                big.NewInt(0),
+				DAOForkBlock:                  nil,
+				DAOForkSupport:                true,
+				EIP150Block:                   big.NewInt(0),
+				EIP155Block:                   big.NewInt(0),
+				EIP158Block:                   big.NewInt(0),
+				ByzantiumBlock:                big.NewInt(0),
+				ConstantinopleBlock:           big.NewInt(0),
+				PetersburgBlock:               big.NewInt(0),
+				IstanbulBlock:                 big.NewInt(0),
+				MuirGlacierBlock:              big.NewInt(0),
+				BerlinBlock:                   big.NewInt(0),
+				LondonBlock:                   big.NewInt(0),
+				TerminalTotalDifficulty:       big.NewInt(0),
+				TerminalTotalDifficultyPassed: true,
+				MergeNetsplitBlock:            big.NewInt(0),
+				ShanghaiTime:                  &shanghai,
+				CancunTime:                    &cancun,
+				Ethash:                        new(params.EthashConfig),
+			}
+		}
+	)
+	tests := []struct {
+		config *params.ChainConfig
+		want   ID
+	}{
+		// Shanghai active before genesis, skip
+		{config(time-1, time+1), ID{Hash: forkidHash, Next: time + 1}},
+
+		// Shanghai active at genesis, skip
+		{config(time, time+1), ID{Hash: forkidHash, Next: time + 1}},
+
+		// Shanghai not active, skip
+		{config(time+1, time+2), ID{Hash: forkidHash, Next: time + 1}},
+	}
+	for _, tt := range tests {
+		if have := NewID(tt.config, genesis, 0, time); have != tt.want {
+			t.Fatalf("incorrect forkid hash: have %x, want %x", have, tt.want)
+		}
+	}
+}