validate signature size on SendTransactionWithSignature (#1401)

* chekc signature size to avoid panic from go-ethereum

* add comment and constant

* add test

transactions/transactor.go

@@ -3,6 +3,7 @@ package transactions
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"math/big"
 	"sync"
@@ -24,8 +25,13 @@ const (
 	sendTxTimeout = 300 * time.Second
 
 	defaultGas = 90000
+
+	validSignatureSize = 65
 )
 
+// ErrInvalidSignatureSize is returned if a signature is not 65 bytes to avoid panic from go-ethereum
+var ErrInvalidSignatureSize = errors.New("signature size must be 65")
+
 type ErrBadNonce struct {
 	nonce         uint64
 	expectedNonce uint64
@@ -88,6 +94,10 @@ func (t *Transactor) SendTransactionWithSignature(args SendTxArgs, sig []byte) (
 		return hash, ErrInvalidSendTxArgs
 	}
 
+	if len(sig) != validSignatureSize {
+		return hash, ErrInvalidSignatureSize
+	}
+
 	chainID := big.NewInt(int64(t.networkID))
 	signer := types.NewEIP155Signer(chainID)
 

transactions/transactor_test.go

@@ -374,6 +374,12 @@ func (s *TransactorSuite) TestSendTransactionWithSignature() {
 	}
 }
 
+func (s *TransactorSuite) TestSendTransactionWithSignature_InvalidSignature() {
+	args := SendTxArgs{}
+	_, err := s.manager.SendTransactionWithSignature(args, []byte{})
+	s.Equal(ErrInvalidSignatureSize, err)
+}
+
 func (s *TransactorSuite) TestHashTransaction() {
 	privKey, err := crypto.GenerateKey()
 	s.Require().NoError(err)