core/types, internal/ethapi: add back blobs after signing

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

@@ -499,6 +499,9 @@ func (s *PersonalAccountAPI) SignTransaction(ctx context.Context, args Transacti
 	if args.GasPrice == nil && (args.MaxFeePerGas == nil || args.MaxPriorityFeePerGas == 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")
 	}
@@ -1892,6 +1895,16 @@ 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{
+			args.Blobs,
+			args.Commitments,
+			args.Proofs,
+		})
+	}
 	data, err := signed.MarshalBinary()
 	if err != nil {
 		return nil, err