signer: implement blob txs sendtxargs, enable blobtx-signing (#28976)

This change makes it possible to sign blob transactions

Author: holiman

accounts/external/backend.go

@@ -205,7 +205,7 @@ func (api *ExternalSigner) SignTx(account accounts.Account, tx *types.Transactio
 		to = &t
 	}
 	args := &apitypes.SendTxArgs{
-		Data:  &data,
+		Input: &data,
 		Nonce: hexutil.Uint64(tx.Nonce()),
 		Value: hexutil.Big(*tx.Value()),
 		Gas:   hexutil.Uint64(tx.Gas()),
@@ -215,7 +215,7 @@ func (api *ExternalSigner) SignTx(account accounts.Account, tx *types.Transactio
 	switch tx.Type() {
 	case types.LegacyTxType, types.AccessListTxType:
 		args.GasPrice = (*hexutil.Big)(tx.GasPrice())
-	case types.DynamicFeeTxType:
+	case types.DynamicFeeTxType, types.BlobTxType:
 		args.MaxFeePerGas = (*hexutil.Big)(tx.GasFeeCap())
 		args.MaxPriorityFeePerGas = (*hexutil.Big)(tx.GasTipCap())
 	default:
@@ -235,6 +235,17 @@ func (api *ExternalSigner) SignTx(account accounts.Account, tx *types.Transactio
 		accessList := tx.AccessList()
 		args.AccessList = &accessList
 	}
+	if tx.Type() == types.BlobTxType {
+		args.BlobHashes = tx.BlobHashes()
+		sidecar := tx.BlobTxSidecar()
+		if sidecar == nil {
+			return nil, fmt.Errorf("blobs must be present for signing")
+		}
+		args.Blobs = sidecar.Blobs
+		args.Commitments = sidecar.Commitments
+		args.Proofs = sidecar.Proofs
+	}
+
 	var res signTransactionResult
 	if err := api.client.Call(&res, "account_signTransaction", args); err != nil {
 		return nil, err

core/types/transaction.go

@@ -446,6 +446,26 @@ func (tx *Transaction) WithoutBlobTxSidecar() *Transaction {
 	return cpy
 }
 
+// WithBlobTxSidecar returns a copy of tx with the blob sidecar added.
+func (tx *Transaction) WithBlobTxSidecar(sideCar *BlobTxSidecar) *Transaction {
+	blobtx, ok := tx.inner.(*BlobTx)
+	if !ok {
+		return tx
+	}
+	cpy := &Transaction{
+		inner: blobtx.withSidecar(sideCar),
+		time:  tx.time,
+	}
+	// Note: tx.size cache not carried over because the sidecar is included in size!
+	if h := tx.hash.Load(); h != nil {
+		cpy.hash.Store(h)
+	}
+	if f := tx.from.Load(); f != nil {
+		cpy.from.Store(f)
+	}
+	return cpy
+}
+
 // SetTime sets the decoding time of a transaction. This is used by tests to set
 // arbitrary times and by persistent transaction pools when loading old txs from
 // disk.

core/types/tx_blob.go

@@ -191,6 +191,12 @@ func (tx *BlobTx) withoutSidecar() *BlobTx {
 	return &cpy
 }
 
+func (tx *BlobTx) withSidecar(sideCar *BlobTxSidecar) *BlobTx {
+	cpy := *tx
+	cpy.Sidecar = sideCar
+	return &cpy
+}
+
 func (tx *BlobTx) encode(b *bytes.Buffer) error {
 	if tx.Sidecar == nil {
 		return rlp.Encode(b, tx)

internal/ethapi/api.go

@@ -1865,15 +1865,14 @@ type SignTransactionResult struct {
 // The node needs to have the private key of the account corresponding with
 // the given from address and it needs to be unlocked.
 func (s *TransactionAPI) SignTransaction(ctx context.Context, args TransactionArgs) (*SignTransactionResult, error) {
+	args.blobSidecarAllowed = true
+
 	if args.Gas == nil {
 		return nil, errors.New("gas not specified")
 	}
 	if args.GasPrice == nil && (args.MaxPriorityFeePerGas == nil || args.MaxFeePerGas == nil) {
 		return nil, errors.New("missing gasPrice or maxFeePerGas/maxPriorityFeePerGas")
 	}
-	if args.IsEIP4844() {
-		return nil, errBlobTxNotSupported
-	}
 	if args.Nonce == nil {
 		return nil, errors.New("nonce not specified")
 	}
@@ -1889,6 +1888,16 @@ func (s *TransactionAPI) SignTransaction(ctx context.Context, args TransactionAr
 	if err != nil {
 		return nil, err
 	}
+	// If the transaction-to-sign was a blob transaction, then the signed one
+	// no longer retains the blobs, only the blob hashes. In this step, we need
+	// to put back the blob(s).
+	if args.IsEIP4844() {
+		signed = signed.WithBlobTxSidecar(&types.BlobTxSidecar{
+			Blobs:       args.Blobs,
+			Commitments: args.Commitments,
+			Proofs:      args.Proofs,
+		})
+	}
 	data, err := signed.MarshalBinary()
 	if err != nil {
 		return nil, err

internal/ethapi/api_test.go

@@ -1037,11 +1037,8 @@ func TestSignBlobTransaction(t *testing.T) {
 	}
 
 	_, err = api.SignTransaction(context.Background(), argsFromTransaction(res.Tx, b.acc.Address))
-	if err == nil {
-		t.Fatalf("should fail on blob transaction")
-	}
-	if !errors.Is(err, errBlobTxNotSupported) {
-		t.Errorf("error mismatch. Have: %v, want: %v", err, errBlobTxNotSupported)
+	if err != nil {
+		t.Fatalf("should not fail on blob transaction")
 	}
 }
 

internal/ethapi/transaction_args.go

@@ -97,7 +97,7 @@ func (args *TransactionArgs) data() []byte {
 
 // setDefaults fills in default values for unspecified tx fields.
 func (args *TransactionArgs) setDefaults(ctx context.Context, b Backend, skipGasEstimation bool) error {
-	if err := args.setBlobTxSidecar(ctx, b); err != nil {
+	if err := args.setBlobTxSidecar(ctx); err != nil {
 		return err
 	}
 	if err := args.setFeeDefaults(ctx, b); err != nil {
@@ -290,7 +290,7 @@ func (args *TransactionArgs) setLondonFeeDefaults(ctx context.Context, head *typ
 }
 
 // setBlobTxSidecar adds the blob tx
-func (args *TransactionArgs) setBlobTxSidecar(ctx context.Context, b Backend) error {
+func (args *TransactionArgs) setBlobTxSidecar(ctx context.Context) error {
 	// No blobs, we're done.
 	if args.Blobs == nil {
 		return nil

signer/core/api.go

@@ -590,7 +590,10 @@ func (api *SignerAPI) SignTransaction(ctx context.Context, args apitypes.SendTxA
 		return nil, err
 	}
 	// Convert fields into a real transaction
-	var unsignedTx = result.Transaction.ToTransaction()
+	unsignedTx, err := result.Transaction.ToTransaction()
+	if err != nil {
+		return nil, err
+	}
 	// Get the password for the transaction
 	pw, err := api.lookupOrQueryPassword(acc.Address, "Account password",
 		fmt.Sprintf("Please enter the password for account %s", acc.Address.String()))

signer/core/apitypes/types.go

@@ -18,6 +18,7 @@ package apitypes
 
 import (
 	"bytes"
+	"crypto/sha256"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -34,6 +35,8 @@ import (
 	"github.com/ethereum/go-ethereum/common/math"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/crypto/kzg4844"
+	"github.com/holiman/uint256"
 )
 
 var typedDataReferenceTypeRegexp = regexp.MustCompile(`^[A-Za-z](\w*)(\[\])?$`)
@@ -92,12 +95,21 @@ type SendTxArgs struct {
 	// We accept "data" and "input" for backwards-compatibility reasons.
 	// "input" is the newer name and should be preferred by clients.
 	// Issue detail: https://github.com/ethereum/go-ethereum/issues/15628
-	Data  *hexutil.Bytes `json:"data"`
+	Data  *hexutil.Bytes `json:"data,omitempty"`
 	Input *hexutil.Bytes `json:"input,omitempty"`
 
 	// For non-legacy transactions
 	AccessList *types.AccessList `json:"accessList,omitempty"`
 	ChainID    *hexutil.Big      `json:"chainId,omitempty"`
+
+	// For BlobTxType
+	BlobFeeCap *hexutil.Big  `json:"maxFeePerBlobGas,omitempty"`
+	BlobHashes []common.Hash `json:"blobVersionedHashes,omitempty"`
+
+	// For BlobTxType transactions with blob sidecar
+	Blobs       []kzg4844.Blob       `json:"blobs,omitempty"`
+	Commitments []kzg4844.Commitment `json:"commitments,omitempty"`
+	Proofs      []kzg4844.Proof      `json:"proofs,omitempty"`
 }
 
 func (args SendTxArgs) String() string {
@@ -108,24 +120,56 @@ func (args SendTxArgs) String() string {
 	return err.Error()
 }
 
+// data retrieves the transaction calldata. Input field is preferred.
+func (args *SendTxArgs) data() []byte {
+	if args.Input != nil {
+		return *args.Input
+	}
+	if args.Data != nil {
+		return *args.Data
+	}
+	return nil
+}
+
 // ToTransaction converts the arguments to a transaction.
-func (args *SendTxArgs) ToTransaction() *types.Transaction {
+func (args *SendTxArgs) ToTransaction() (*types.Transaction, error) {
 	// Add the To-field, if specified
 	var to *common.Address
 	if args.To != nil {
 		dstAddr := args.To.Address()
 		to = &dstAddr
 	}
-
-	var input []byte
-	if args.Input != nil {
-		input = *args.Input
-	} else if args.Data != nil {
-		input = *args.Data
+	if err := args.validateTxSidecar(); err != nil {
+		return nil, err
 	}
-
 	var data types.TxData
 	switch {
+	case args.BlobHashes != nil:
+		al := types.AccessList{}
+		if args.AccessList != nil {
+			al = *args.AccessList
+		}
+		data = &types.BlobTx{
+			To:         *to,
+			ChainID:    uint256.MustFromBig((*big.Int)(args.ChainID)),
+			Nonce:      uint64(args.Nonce),
+			Gas:        uint64(args.Gas),
+			GasFeeCap:  uint256.MustFromBig((*big.Int)(args.MaxFeePerGas)),
+			GasTipCap:  uint256.MustFromBig((*big.Int)(args.MaxPriorityFeePerGas)),
+			Value:      uint256.MustFromBig((*big.Int)(&args.Value)),
+			Data:       args.data(),
+			AccessList: al,
+			BlobHashes: args.BlobHashes,
+			BlobFeeCap: uint256.MustFromBig((*big.Int)(args.BlobFeeCap)),
+		}
+		if args.Blobs != nil {
+			data.(*types.BlobTx).Sidecar = &types.BlobTxSidecar{
+				Blobs:       args.Blobs,
+				Commitments: args.Commitments,
+				Proofs:      args.Proofs,
+			}
+		}
+
 	case args.MaxFeePerGas != nil:
 		al := types.AccessList{}
 		if args.AccessList != nil {
@@ -139,7 +183,7 @@ func (args *SendTxArgs) ToTransaction() *types.Transaction {
 			GasFeeCap:  (*big.Int)(args.MaxFeePerGas),
 			GasTipCap:  (*big.Int)(args.MaxPriorityFeePerGas),
 			Value:      (*big.Int)(&args.Value),
-			Data:       input,
+			Data:       args.data(),
 			AccessList: al,
 		}
 	case args.AccessList != nil:
@@ -150,7 +194,7 @@ func (args *SendTxArgs) ToTransaction() *types.Transaction {
 			Gas:        uint64(args.Gas),
 			GasPrice:   (*big.Int)(args.GasPrice),
 			Value:      (*big.Int)(&args.Value),
-			Data:       input,
+			Data:       args.data(),
 			AccessList: *args.AccessList,
 		}
 	default:
@@ -160,10 +204,81 @@ func (args *SendTxArgs) ToTransaction() *types.Transaction {
 			Gas:      uint64(args.Gas),
 			GasPrice: (*big.Int)(args.GasPrice),
 			Value:    (*big.Int)(&args.Value),
-			Data:     input,
+			Data:     args.data(),
 		}
 	}
-	return types.NewTx(data)
+
+	return types.NewTx(data), nil
+}
+
+// validateTxSidecar validates blob data, if present
+func (args *SendTxArgs) validateTxSidecar() error {
+	// No blobs, we're done.
+	if args.Blobs == nil {
+		return nil
+	}
+
+	n := len(args.Blobs)
+	// Assume user provides either only blobs (w/o hashes), or
+	// blobs together with commitments and proofs.
+	if args.Commitments == nil && args.Proofs != nil {
+		return errors.New(`blob proofs provided while commitments were not`)
+	} else if args.Commitments != nil && args.Proofs == nil {
+		return errors.New(`blob commitments provided while proofs were not`)
+	}
+
+	// len(blobs) == len(commitments) == len(proofs) == len(hashes)
+	if args.Commitments != nil && len(args.Commitments) != n {
+		return fmt.Errorf("number of blobs and commitments mismatch (have=%d, want=%d)", len(args.Commitments), n)
+	}
+	if args.Proofs != nil && len(args.Proofs) != n {
+		return fmt.Errorf("number of blobs and proofs mismatch (have=%d, want=%d)", len(args.Proofs), n)
+	}
+	if args.BlobHashes != nil && len(args.BlobHashes) != n {
+		return fmt.Errorf("number of blobs and hashes mismatch (have=%d, want=%d)", len(args.BlobHashes), n)
+	}
+
+	if args.Commitments == nil {
+		// Generate commitment and proof.
+		commitments := make([]kzg4844.Commitment, n)
+		proofs := make([]kzg4844.Proof, n)
+		for i, b := range args.Blobs {
+			c, err := kzg4844.BlobToCommitment(b)
+			if err != nil {
+				return fmt.Errorf("blobs[%d]: error computing commitment: %v", i, err)
+			}
+			commitments[i] = c
+			p, err := kzg4844.ComputeBlobProof(b, c)
+			if err != nil {
+				return fmt.Errorf("blobs[%d]: error computing proof: %v", i, err)
+			}
+			proofs[i] = p
+		}
+		args.Commitments = commitments
+		args.Proofs = proofs
+	} else {
+		for i, b := range args.Blobs {
+			if err := kzg4844.VerifyBlobProof(b, args.Commitments[i], args.Proofs[i]); err != nil {
+				return fmt.Errorf("failed to verify blob proof: %v", err)
+			}
+		}
+	}
+
+	hashes := make([]common.Hash, n)
+	hasher := sha256.New()
+	for i, c := range args.Commitments {
+		hashes[i] = kzg4844.CalcBlobHashV1(hasher, &c)
+	}
+	if args.BlobHashes != nil {
+		for i, h := range hashes {
+			if h != args.BlobHashes[i] {
+				return fmt.Errorf("blob hash verification failed (have=%s, want=%s)", args.BlobHashes[i], h)
+			}
+		}
+	} else {
+		args.BlobHashes = hashes
+	}
+	return nil
 }
 
 type SigFormat struct {