fix: non-eip-155 tx panic when get signer (cosmos#282)

Author: yihuang

api/cosmos/evm/vm/v1/msg.go

@@ -21,7 +21,13 @@ var supportedTxs = map[string]func() TxDataV2{
 
 // getSender extracts the sender address from the signature values using the latest signer for the given chainID.
 func getSender(txData TxDataV2) (common.Address, error) {
-	signer := ethtypes.LatestSignerForChainID(txData.GetChainID())
+	chainID := txData.GetChainID()
+	// legacy tx returns `0` as chainID when EIP-155 is not used
+	// see: DeriveChainID
+	if chainID != nil && chainID.Sign() == 0 {
+		chainID = nil
+	}
+	signer := ethtypes.LatestSignerForChainID(chainID)
 	from, err := signer.Sender(ethtypes.NewTx(txData.AsEthereumData()))
 	if err != nil {
 		return common.Address{}, err

utils/eth/eth.go

@@ -9,6 +9,8 @@ import "math/big"
 //   - {0,1} + CHAIN_ID * 2 + 35, if EIP155 is used
 //   - {0,1} + 27, otherwise
 //
+// when EIP155 is not used, chain id `0` is returned.
+//
 // Ref: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-155.md
 func DeriveChainID(v *big.Int) *big.Int {
 	if v == nil || v.Sign() < 1 {