vault-ethereum-error.go

package main

import (
	"encoding/json"
	"fmt"

	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/crypto"
)

func main() {
	// method id. this is byte array [33 26 23 197]
	id := getMethodID("someTransactionMethod()");
	fmt.Println("id: ", id)

	fmt.Println("--- Cast String ---")
	// cast string
	str := string(id)
	strAfter := throughJSON(str)
	check("str", str, strAfter)
	strDecoded := []byte(strAfter)
	fmt.Println("[Result]str decoded: ", strDecoded)

	fmt.Println("--- Hex ---")
	// hex
	hex := hexutil.Encode(id)
	hexAfter := throughJSON(hex)
	hexDecoded, _ := hexutil.Decode(hexAfter)
	check("hex", hex, hexAfter)
	fmt.Println("[Result]hex decoded: ", hexDecoded)
}

func getMethodID(sig string) []byte {
	// method string signature -> byte array -> keccak hash
	sigByte := []byte(sig)
	sigHash := crypto.Keccak256(sigByte)
	// hash -> id (getting head 4 bytes from hash)
	id := sigHash[:4]
	return id
}

func throughJSON(text string) string {
	// marshal to json byte
	j, _ := json.Marshal(map[string]interface{}{
		"text": text,
	})

	// unmarshal to json byte and return unmarshaled value
	m := map[string]interface{}{}
	json.Unmarshal(j, &m)
	return m["text"].(string)
}

func check(label, before, after string) {
	fmt.Printf("[Check] '%s' : same='%v', before='%v', after='%v'\n", label,  before == after, before, after)
}