package util import ( "math/big" "github.com/ethereum/go-ethereum/common" "golang.org/x/crypto/sha3" ) // EvmContractMethodId encodes a method signature to the method id used in eth calldata. func EvmContractMethodId(signature string) []byte { transferFnSignature := []byte(signature) hash := sha3.NewLegacyKeccak256() hash.Write(transferFnSignature) return hash.Sum(nil)[:4] } func BuildErc20TransferCallData(from common.Address, to common.Address, amount *big.Int) []byte { methodId := EvmContractMethodId("transfer(address,uint256)") paddedAddress := common.LeftPadBytes(to.Bytes(), 32) paddedAmount := common.LeftPadBytes(amount.Bytes(), 32) var data []byte data = append(data, methodId...) data = append(data, paddedAddress...) data = append(data, paddedAmount...) return data } func BuildErc20BalanceOfCallData(address common.Address) []byte { methodId := EvmContractMethodId("balanceOf(address)") paddedAddress := common.LeftPadBytes(address.Bytes(), 32) var data []byte data = append(data, methodId...) data = append(data, paddedAddress...) return data }