core/types: cleanup tx signer logic (ethereum#31434)

This removes the signer type-train in favor of defining a single object
that can handle all tx types. Supported types are enabled via a map.
Notably, the new signer also supports disabling legacy transactions.

Author: fjl

cmd/evm/internal/t8ntool/tx_iterator.go

@@ -102,7 +102,7 @@ func signUnsignedTransactions(txs []*txWithKey, signer types.Signer) (types.Tran
 		if tx.protected {
 			signed, err = types.SignTx(tx.tx, signer, tx.key)
 		} else {
-			signed, err = types.SignTx(tx.tx, types.FrontierSigner{}, tx.key)
+			signed, err = types.SignTx(tx.tx, types.HomesteadSigner{}, tx.key)
 		}
 		if err != nil {
 			return nil, NewError(ErrorJson, fmt.Errorf("tx %d: failed to sign tx: %v", i, err))

core/types/transaction_signing.go

@@ -20,11 +20,13 @@ import (
 	"crypto/ecdsa"
 	"errors"
 	"fmt"
+	"maps"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/params/forks"
 )
 
 var ErrInvalidChainId = errors.New("invalid chain id for signer")
@@ -178,245 +180,141 @@ type Signer interface {
 	Equal(Signer) bool
 }
 
-type pragueSigner struct{ cancunSigner }
-
-// NewPragueSigner returns a signer that accepts
-// - EIP-7702 set code transactions
-// - EIP-4844 blob transactions
-// - EIP-1559 dynamic fee transactions
-// - EIP-2930 access list transactions,
-// - EIP-155 replay protected transactions, and
-// - legacy Homestead transactions.
-func NewPragueSigner(chainId *big.Int) Signer {
-	signer, _ := NewCancunSigner(chainId).(cancunSigner)
-	return pragueSigner{signer}
+// modernSigner is the signer implementation that handles non-legacy transaction types.
+// For legacy transactions, it defers to one of the legacy signers (frontier, homestead, eip155).
+type modernSigner struct {
+	txtypes map[byte]struct{}
+	chainID *big.Int
+	legacy  Signer
 }
 
-func (s pragueSigner) Sender(tx *Transaction) (common.Address, error) {
-	if tx.Type() != SetCodeTxType {
-		return s.cancunSigner.Sender(tx)
+func newModernSigner(chainID *big.Int, fork forks.Fork) Signer {
+	if chainID == nil || chainID.Sign() <= 0 {
+		panic(fmt.Sprintf("invalid chainID %v", chainID))
 	}
-	V, R, S := tx.RawSignatureValues()
-
-	// Set code txs are defined to use 0 and 1 as their recovery
-	// id, add 27 to become equivalent to unprotected Homestead signatures.
-	V = new(big.Int).Add(V, big.NewInt(27))
-	if tx.ChainId().Cmp(s.chainId) != 0 {
-		return common.Address{}, fmt.Errorf("%w: have %d want %d", ErrInvalidChainId, tx.ChainId(), s.chainId)
+	s := &modernSigner{
+		chainID: chainID,
+		txtypes: make(map[byte]struct{}, 4),
 	}
-	return recoverPlain(s.Hash(tx), R, S, V, true)
+	// configure legacy signer
+	switch {
+	case fork >= forks.SpuriousDragon:
+		s.legacy = NewEIP155Signer(chainID)
+	case fork >= forks.Homestead:
+		s.legacy = HomesteadSigner{}
+	default:
+		s.legacy = FrontierSigner{}
+	}
+	s.txtypes[LegacyTxType] = struct{}{}
+	// configure tx types
+	if fork >= forks.Berlin {
+		s.txtypes[AccessListTxType] = struct{}{}
+	}
+	if fork >= forks.London {
+		s.txtypes[DynamicFeeTxType] = struct{}{}
+	}
+	if fork >= forks.Cancun {
+		s.txtypes[BlobTxType] = struct{}{}
+	}
+	if fork >= forks.Prague {
+		s.txtypes[SetCodeTxType] = struct{}{}
+	}
+	return s
 }
 
-func (s pragueSigner) Equal(s2 Signer) bool {
-	x, ok := s2.(pragueSigner)
-	return ok && x.chainId.Cmp(s.chainId) == 0
+func (s *modernSigner) ChainID() *big.Int {
+	return s.chainID
 }
 
-func (s pragueSigner) SignatureValues(tx *Transaction, sig []byte) (R, S, V *big.Int, err error) {
-	txdata, ok := tx.inner.(*SetCodeTx)
-	if !ok {
-		return s.cancunSigner.SignatureValues(tx, sig)
-	}
-	// Check that chain ID of tx matches the signer. We also accept ID zero here,
-	// because it indicates that the chain ID was not specified in the tx.
-	if txdata.ChainID.Sign() != 0 && txdata.ChainID.CmpBig(s.chainId) != 0 {
-		return nil, nil, nil, fmt.Errorf("%w: have %d want %d", ErrInvalidChainId, txdata.ChainID, s.chainId)
-	}
-	R, S, _ = decodeSignature(sig)
-	V = big.NewInt(int64(sig[64]))
-	return R, S, V, nil
+func (s *modernSigner) Equal(s2 Signer) bool {
+	other, ok := s2.(*modernSigner)
+	return ok && s.chainID.Cmp(other.chainID) == 0 && maps.Equal(s.txtypes, other.txtypes) && s.legacy.Equal(other.legacy)
 }
 
-// Hash returns the hash to be signed by the sender.
-// It does not uniquely identify the transaction.
-func (s pragueSigner) Hash(tx *Transaction) common.Hash {
-	if tx.Type() != SetCodeTxType {
-		return s.cancunSigner.Hash(tx)
-	}
-	return tx.inner.sigHash(s.chainId)
+func (s *modernSigner) Hash(tx *Transaction) common.Hash {
+	return tx.inner.sigHash(s.chainID)
 }
 
-type cancunSigner struct{ londonSigner }
-
-// NewCancunSigner returns a signer that accepts
-// - EIP-4844 blob transactions
-// - EIP-1559 dynamic fee transactions
-// - EIP-2930 access list transactions,
-// - EIP-155 replay protected transactions, and
-// - legacy Homestead transactions.
-func NewCancunSigner(chainId *big.Int) Signer {
-	return cancunSigner{londonSigner{eip2930Signer{NewEIP155Signer(chainId)}}}
+func (s *modernSigner) supportsType(txtype byte) bool {
+	_, ok := s.txtypes[txtype]
+	return ok
 }
 
-func (s cancunSigner) Sender(tx *Transaction) (common.Address, error) {
-	if tx.Type() != BlobTxType {
-		return s.londonSigner.Sender(tx)
+func (s *modernSigner) Sender(tx *Transaction) (common.Address, error) {
+	tt := tx.Type()
+	if !s.supportsType(tt) {
+		return common.Address{}, ErrTxTypeNotSupported
 	}
-	V, R, S := tx.RawSignatureValues()
-	// Blob txs are defined to use 0 and 1 as their recovery
+	if tt == LegacyTxType {
+		return s.legacy.Sender(tx)
+	}
+	if tx.ChainId().Cmp(s.chainID) != 0 {
+		return common.Address{}, fmt.Errorf("%w: have %d want %d", ErrInvalidChainId, tx.ChainId(), s.chainID)
+	}
+	// 'modern' txs are defined to use 0 and 1 as their recovery
 	// id, add 27 to become equivalent to unprotected Homestead signatures.
+	V, R, S := tx.RawSignatureValues()
 	V = new(big.Int).Add(V, big.NewInt(27))
-	if tx.ChainId().Cmp(s.chainId) != 0 {
-		return common.Address{}, fmt.Errorf("%w: have %d want %d", ErrInvalidChainId, tx.ChainId(), s.chainId)
-	}
 	return recoverPlain(s.Hash(tx), R, S, V, true)
 }
 
-func (s cancunSigner) Equal(s2 Signer) bool {
-	x, ok := s2.(cancunSigner)
-	return ok && x.chainId.Cmp(s.chainId) == 0
-}
-
-func (s cancunSigner) SignatureValues(tx *Transaction, sig []byte) (R, S, V *big.Int, err error) {
-	txdata, ok := tx.inner.(*BlobTx)
-	if !ok {
-		return s.londonSigner.SignatureValues(tx, sig)
+func (s *modernSigner) SignatureValues(tx *Transaction, sig []byte) (R, S, V *big.Int, err error) {
+	tt := tx.Type()
+	if !s.supportsType(tt) {
+		return nil, nil, nil, ErrTxTypeNotSupported
+	}
+	if tt == LegacyTxType {
+		return s.legacy.SignatureValues(tx, sig)
 	}
 	// Check that chain ID of tx matches the signer. We also accept ID zero here,
 	// because it indicates that the chain ID was not specified in the tx.
-	if txdata.ChainID.Sign() != 0 && txdata.ChainID.CmpBig(s.chainId) != 0 {
-		return nil, nil, nil, fmt.Errorf("%w: have %d want %d", ErrInvalidChainId, txdata.ChainID, s.chainId)
+	if tx.inner.chainID().Sign() != 0 && tx.inner.chainID().Cmp(s.chainID) != 0 {
+		return nil, nil, nil, fmt.Errorf("%w: have %d want %d", ErrInvalidChainId, tx.inner.chainID(), s.chainID)
 	}
 	R, S, _ = decodeSignature(sig)
 	V = big.NewInt(int64(sig[64]))
 	return R, S, V, nil
 }
 
-// Hash returns the hash to be signed by the sender.
-// It does not uniquely identify the transaction.
-func (s cancunSigner) Hash(tx *Transaction) common.Hash {
-	if tx.Type() != BlobTxType {
-		return s.londonSigner.Hash(tx)
-	}
-	return tx.inner.sigHash(s.chainId)
+// NewPragueSigner returns a signer that accepts
+// - EIP-7702 set code transactions
+// - EIP-4844 blob transactions
+// - EIP-1559 dynamic fee transactions
+// - EIP-2930 access list transactions,
+// - EIP-155 replay protected transactions, and
+// - legacy Homestead transactions.
+func NewPragueSigner(chainId *big.Int) Signer {
+	return newModernSigner(chainId, forks.Prague)
 }
 
-type londonSigner struct{ eip2930Signer }
+// NewCancunSigner returns a signer that accepts
+// - EIP-4844 blob transactions
+// - EIP-1559 dynamic fee transactions
+// - EIP-2930 access list transactions,
+// - EIP-155 replay protected transactions, and
+// - legacy Homestead transactions.
+func NewCancunSigner(chainId *big.Int) Signer {
+	return newModernSigner(chainId, forks.Cancun)
+}
 
 // NewLondonSigner returns a signer that accepts
 // - EIP-1559 dynamic fee transactions
 // - EIP-2930 access list transactions,
 // - EIP-155 replay protected transactions, and
 // - legacy Homestead transactions.
 func NewLondonSigner(chainId *big.Int) Signer {
-	return londonSigner{eip2930Signer{NewEIP155Signer(chainId)}}
+	return newModernSigner(chainId, forks.London)
 }
 
-func (s londonSigner) Sender(tx *Transaction) (common.Address, error) {
-	if tx.Type() != DynamicFeeTxType {
-		return s.eip2930Signer.Sender(tx)
-	}
-	V, R, S := tx.RawSignatureValues()
-	// DynamicFee txs are defined to use 0 and 1 as their recovery
-	// id, add 27 to become equivalent to unprotected Homestead signatures.
-	V = new(big.Int).Add(V, big.NewInt(27))
-	if tx.ChainId().Cmp(s.chainId) != 0 {
-		return common.Address{}, fmt.Errorf("%w: have %d want %d", ErrInvalidChainId, tx.ChainId(), s.chainId)
-	}
-	return recoverPlain(s.Hash(tx), R, S, V, true)
-}
-
-func (s londonSigner) Equal(s2 Signer) bool {
-	x, ok := s2.(londonSigner)
-	return ok && x.chainId.Cmp(s.chainId) == 0
-}
-
-func (s londonSigner) SignatureValues(tx *Transaction, sig []byte) (R, S, V *big.Int, err error) {
-	txdata, ok := tx.inner.(*DynamicFeeTx)
-	if !ok {
-		return s.eip2930Signer.SignatureValues(tx, sig)
-	}
-	// Check that chain ID of tx matches the signer. We also accept ID zero here,
-	// because it indicates that the chain ID was not specified in the tx.
-	if txdata.ChainID.Sign() != 0 && txdata.ChainID.Cmp(s.chainId) != 0 {
-		return nil, nil, nil, fmt.Errorf("%w: have %d want %d", ErrInvalidChainId, txdata.ChainID, s.chainId)
-	}
-	R, S, _ = decodeSignature(sig)
-	V = big.NewInt(int64(sig[64]))
-	return R, S, V, nil
-}
-
-// Hash returns the hash to be signed by the sender.
-// It does not uniquely identify the transaction.
-func (s londonSigner) Hash(tx *Transaction) common.Hash {
-	if tx.Type() != DynamicFeeTxType {
-		return s.eip2930Signer.Hash(tx)
-	}
-	return tx.inner.sigHash(s.chainId)
-}
-
-type eip2930Signer struct{ EIP155Signer }
-
 // NewEIP2930Signer returns a signer that accepts EIP-2930 access list transactions,
 // EIP-155 replay protected transactions, and legacy Homestead transactions.
 func NewEIP2930Signer(chainId *big.Int) Signer {
-	return eip2930Signer{NewEIP155Signer(chainId)}
-}
-
-func (s eip2930Signer) ChainID() *big.Int {
-	return s.chainId
-}
-
-func (s eip2930Signer) Equal(s2 Signer) bool {
-	x, ok := s2.(eip2930Signer)
-	return ok && x.chainId.Cmp(s.chainId) == 0
-}
-
-func (s eip2930Signer) Sender(tx *Transaction) (common.Address, error) {
-	V, R, S := tx.RawSignatureValues()
-	switch tx.Type() {
-	case LegacyTxType:
-		return s.EIP155Signer.Sender(tx)
-	case AccessListTxType:
-		// AL txs are defined to use 0 and 1 as their recovery
-		// id, add 27 to become equivalent to unprotected Homestead signatures.
-		V = new(big.Int).Add(V, big.NewInt(27))
-	default:
-		return common.Address{}, ErrTxTypeNotSupported
-	}
-	if tx.ChainId().Cmp(s.chainId) != 0 {
-		return common.Address{}, fmt.Errorf("%w: have %d want %d", ErrInvalidChainId, tx.ChainId(), s.chainId)
-	}
-	return recoverPlain(s.Hash(tx), R, S, V, true)
-}
-
-func (s eip2930Signer) SignatureValues(tx *Transaction, sig []byte) (R, S, V *big.Int, err error) {
-	switch txdata := tx.inner.(type) {
-	case *LegacyTx:
-		return s.EIP155Signer.SignatureValues(tx, sig)
-	case *AccessListTx:
-		// Check that chain ID of tx matches the signer. We also accept ID zero here,
-		// because it indicates that the chain ID was not specified in the tx.
-		if txdata.ChainID.Sign() != 0 && txdata.ChainID.Cmp(s.chainId) != 0 {
-			return nil, nil, nil, fmt.Errorf("%w: have %d want %d", ErrInvalidChainId, txdata.ChainID, s.chainId)
-		}
-		R, S, _ = decodeSignature(sig)
-		V = big.NewInt(int64(sig[64]))
-	default:
-		return nil, nil, nil, ErrTxTypeNotSupported
-	}
-	return R, S, V, nil
-}
-
-// Hash returns the hash to be signed by the sender.
-// It does not uniquely identify the transaction.
-func (s eip2930Signer) Hash(tx *Transaction) common.Hash {
-	switch tx.Type() {
-	case LegacyTxType:
-		return s.EIP155Signer.Hash(tx)
-	case AccessListTxType:
-		return tx.inner.sigHash(s.chainId)
-	default:
-		// This _should_ not happen, but in case someone sends in a bad
-		// json struct via RPC, it's probably more prudent to return an
-		// empty hash instead of killing the node with a panic
-		//panic("Unsupported transaction type: %d", tx.typ)
-		return common.Hash{}
-	}
+	return newModernSigner(chainId, forks.Berlin)
 }
 
 // EIP155Signer implements Signer using the EIP-155 rules. This accepts transactions which
 // are replay-protected as well as unprotected homestead transactions.
+// Deprecated: always use the Signer interface type
 type EIP155Signer struct {
 	chainId, chainIdMul *big.Int
 }
@@ -478,8 +376,9 @@ func (s EIP155Signer) Hash(tx *Transaction) common.Hash {
 	return tx.inner.sigHash(s.chainId)
 }
 
-// HomesteadSigner implements Signer interface using the
-// homestead rules.
+// HomesteadSigner implements Signer using the homestead rules. The only valid reason to
+// use this type is creating legacy transactions which are intentionally not
+// replay-protected.
 type HomesteadSigner struct{ FrontierSigner }
 
 func (hs HomesteadSigner) ChainID() *big.Int {
@@ -505,8 +404,8 @@ func (hs HomesteadSigner) Sender(tx *Transaction) (common.Address, error) {
 	return recoverPlain(hs.Hash(tx), r, s, v, true)
 }
 
-// FrontierSigner implements Signer interface using the
-// frontier rules.
+// FrontierSigner implements Signer using the frontier rules.
+// Deprecated: always use the Signer interface type
 type FrontierSigner struct{}
 
 func (fs FrontierSigner) ChainID() *big.Int {

params/forks/forks.go

@@ -24,8 +24,8 @@ const (
 	FrontierThawing
 	Homestead
 	DAO
-	TangerineWhistle
-	SpuriousDragon
+	TangerineWhistle // a.k.a. the EIP150 fork
+	SpuriousDragon   // a.k.a. the EIP155 fork
 	Byzantium
 	Constantinople
 	Petersburg