以太坊智能合約地址生成之CREATE指令

以太坊智能合約地址生成是有規則的，是可以提前預測的。底層在虛擬機段是用CREATE命令生成智能合約地址的，當然後來虛擬機升級有新增了CREATE2指令來生成智能合約地址，後面會再寫一篇測試CREATE2.

爲了驗證效果，寫了如下代碼，如果好奇心強烈，可以自行新增測試用例測試一下：

import (
	"encoding/binary"
	"encoding/hex"
	"github.com/ethereum/go-ethereum/rlp"
	"golang.org/x/crypto/sha3"
)

//根據RLP編碼規則把int變量值轉變成字節切片
func RlpInt2Bytes(i int)[]byte {
	var data [4]byte
	if i <= 255 {
		if i == 0 { //我靠，這個坑爹的玩意兒，害我好苦
			return nil
		}
		return []byte{byte(i)}
	} else  {
		binary.LittleEndian.PutUint32(data[:], uint32(i))
		if i<= 0xffff {
			return data[:2]
		} else if i <= 0xffffff {
			binary.LittleEndian.PutUint32(data[:], uint32(i))
			return data[:3]
		}
	}
	return data[:]
}

func Keccak256Hash(data []byte) []byte {
	keccak256Hash2 := sha3.NewLegacyKeccak256()
	keccak256Hash2.Write(data)
	return keccak256Hash2.Sum(nil)
}

//經測試，這種算法適合外部賬號創建智能合約用
//同樣是適用於簡單的智能合約創建另一個智能合約
//但是不適用於用CREATE2 操作碼創建新智能合約
func CreateContractAddr(senderAddr string, nonce int) (string, error) {
	var (
		data [][]byte
		buf []byte
		err error
	)
	if buf, err = hex.DecodeString(senderAddr); err != nil {
		return "",err
	}
	data = append(data, buf)
	buf = RlpInt2Bytes(nonce)
	data = append(data, buf)

	if buf, err = rlp.EncodeToBytes(data);err != nil {
		return "",nil
	}

	buf = Keccak256Hash(buf)
	return hex.EncodeToString(buf[12:]),nil
}

測試代碼:

func TestCreateContractAddr(t *testing.T) {
	var testcases = []struct {
		sender string
		nonce int
		want string
	} {
		{
			"D4a16aa11Bd0D3315698792F5E1F66770F9Cd78F",
			2,
			"a79fa249cad974b1f40124fd11452f8dc325440c",
		},
		{
			"d4a16aa11bd0d3315698792f5e1f66770f9cd78f",
			0,
			"7e4ca94147bea90fe22575e92f89b186af3ea523",
		},
		{
			"6ac7ea33f8831ea9dcc53393aaa88b25a785dbf0",
			0,
			"cd234a471b72ba2f1ccf0a70fcaba648a5eecd8d",
		},
		{
			"6ac7ea33f8831ea9dcc53393aaa88b25a785dbf0",
			1,
			"343c43a37d37dff08ae8c4a11544c718abb4fcf8",
		},
		{
			"6ac7ea33f8831ea9dcc53393aaa88b25a785dbf0",
			2,
			"f778b86fa74e846c4f0a1fbd1335fe81c00a0c91",
		},
		{
			"6ac7ea33f8831ea9dcc53393aaa88b25a785dbf0",
			3,
			"fffd933a0bc612844eaf0c6fe3e5b8e9b6c1d19c",
		},
		{
			"B20e2D38128E976b6B4852293C4e32f3A8D75C22",
			1,
			"53c4554e4e3dc3bf299a46f51dd3dbccaa5ea47a",
		},
		{
			"B20e2D38128E976b6B4852293C4e32f3A8D75C22",
			2,
			"1a125fd865e0f21ade5a37a54f22b08a8e154273",
		},
		//{//這個例子不是用CREATE操作碼實現的，而是用CREATE2操作碼實現的
		//	"40c84310ef15b0c0e5c69d25138e0e16e8000fe9",
		//	6816,
		//	"8b55c928602896a1e078e23a3fee33393821eec7",
		//},
	}
	for _, oneCase := range testcases {
		var got string
		var err error
		if got, err = CreateContractAddr(oneCase.sender, oneCase.nonce); err != nil {
			t.Error(err)
			return
		}

		if got != oneCase.want {
			t.Error("generate contract address error")
			t.Error("want:", oneCase.want)
			t.Error("got: ", got)
			return
		}
	}
}

(全文完)

參考資料：

https://learnblockchain.cn/2019/06/10/address-compute/