為優化 Calldata 而設的精簡 ABI

1    /**
2     * @dev 讓呼叫者獲得 1000 個代幣使用
3     */
4    function faucet() external {
5        _mint(msg.sender, 1000);
6    }   // function faucet
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1//SPDX-License-Identifier: Unlicense
2pragma solidity ^0.8.0;
3
4
5import { OrisUselessToken } from "./Token.sol";
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1contract CalldataInterpreter {
2
3    OrisUselessToken public immutable token;
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1
2    /**
3     * @dev 指定代幣地址
4     * @param tokenAddr_ ERC-20 合約地址
5     */
6    constructor(
7        address tokenAddr_
8    )  {
9        token = OrisUselessToken(tokenAddr_);
10    }   // constructor
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1    function calldataVal(uint startByte, uint length)
2        private pure returns (uint) {
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1        uint _retVal;
2
3        require(length < 0x21,
4            "calldataVal 長度限制為 32 位元組");
5
6        require(length + startByte <= msg.data.length,
7            "calldataVal 嘗試讀取超過 calldatasize");
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1        assembly {
2            _retVal := calldataload(startByte)
3        }
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1
2        _retVal = _retVal >> (256-length*8);
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1
2        return _retVal;
3    }
4
5
6    fallback() external {
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1        uint _func;
2
3        _func = calldataVal(0, 1);
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1
2        // 使用來自 calldata 的資訊
3        // 呼叫代幣的狀態變更方法
4
5        // faucet
6        if (_func == 1) {
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1            token.faucet();
2            token.transfer(msg.sender,
3                token.balanceOf(address(this)));
4        }
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1        // transfer (假設我們有權限這麼做)
2        if (_func == 2) {
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1            token.transferFrom(
2                msg.sender,
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1                address(uint160(calldataVal(1, 20))),
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1                calldataVal(21, 2)
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1            );
2        }
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1    }   // fallback
2
3}       // contract CalldataInterpreter
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1const { expect } = require("chai");
2
3describe("CalldataInterpreter", function () {
4  it("Should let us use tokens", async function () {
5    const Token = await ethers.getContractFactory("OrisUselessToken")
6    const token = await Token.deploy()
7    await token.deployed()
8    console.log("Token addr:", token.address)
9
10    const Cdi = await ethers.getContractFactory("CalldataInterpreter")
11    const cdi = await Cdi.deploy(token.address)
12    await cdi.deployed()
13    console.log("CalldataInterpreter addr:", cdi.address)
14
15    const signer = await ethers.getSigner()
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1    // 取得代幣來使用
2    const faucetTx = {

1      to: cdi.address,
2      data: "0x01"

1
2    }
3    await (await signer.sendTransaction(faucetTx)).wait()

1// 檢查 faucet 是否正確提供代幣
2expect(await token.balanceOf(signer.address)).to.equal(1000)

1// 給予 CDI 額度 (核准無法被代理)
2const approveTX = await token.approve(cdi.address, 10000)
3await approveTX.wait()
4expect(await token.allowance(signer.address, cdi.address)).to.equal(10000)

1// 轉帳代幣
2const destAddr = "0xf5a6ead936fb47f342bb63e676479bddf26ebe1d"
3const transferTx = {
4  to: cdi.address,
5  data: "0x02" + destAddr.slice(2, 42) + "0100",
6}

1    await (await signer.sendTransaction(transferTx)).wait()
2
3    // 檢查我們是否少了 256 個代幣
4    expect (await token.balanceOf(signer.address)).to.equal(1000-256)
5
6    // 以及我們的目標是否收到了它們
7    expect (await token.balanceOf(destAddr)).to.equal(256)
8  })    // it
9})      // describe
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1    // 唯一允許指定 CalldataInterpreter 地址的地址
2    address owner;
3
4    // CalldataInterpreter 地址
5    address proxy = address(0);
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1    /**
2     * @dev 呼叫 ERC20 建構函式。
3     */
4    constructor(
5    ) ERC20("Oris useless token-2", "OUT-2") {
6        owner = msg.sender;
7    }
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1    /**
2     * @dev 設定代理 (CalldataInterpreter) 的地址。
3     * 只能由 owner 呼叫一次
4     */
5    function setProxy(address _proxy) external {
6        require(msg.sender == owner, "只能由 owner 呼叫");
7        require(proxy == address(0), "代理已設定");
8
9        proxy = _proxy;
10    }    // function setProxy
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1    /**
2     * @dev 有些函式可能只能由代理呼叫。
3     */
4    modifier onlyProxy {
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1      require(msg.sender == proxy);
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1      _;
2    }
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1   /* 允許代理實際為帳戶進行代理的函式 */
2
3    function transferProxy(address from, address to, uint256 amount)
4        public virtual onlyProxy() returns (bool)
5    {
6        _transfer(from, to, amount);
7        return true;
8    }
9
10    function approveProxy(address from, address spender, uint256 amount)
11        public virtual onlyProxy() returns (bool)
12    {
13        _approve(from, spender, amount);
14        return true;
15    }
16
17    function transferFromProxy(
18        address spender,
19        address from,
20        address to,
21        uint256 amount
22    ) public virtual onlyProxy() returns (bool)
23    {
24        _spendAllowance(from, spender, amount);
25        _transfer(from, to, amount);
26        return true;
27    }
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1        // transfer (不需額度)
2        if (_func == 2) {
3            token.transferProxy(
4                msg.sender,
5                address(uint160(calldataVal(1, 20))),
6                calldataVal(21, 2)
7            );
8        }
9
10        // approve
11        if (_func == 3) {
12            token.approveProxy(
13                msg.sender,
14                address(uint160(calldataVal(1, 20))),
15                calldataVal(21, 2)
16            );
17        }
18
19        // transferFrom
20        if (_func == 4) {
21            token.transferFromProxy(
22                msg.sender,
23                address(uint160(calldataVal( 1, 20))),
24                address(uint160(calldataVal(21, 20))),
25                calldataVal(41, 2)
26            );
27        }
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1const Cdi = await ethers.getContractFactory("CalldataInterpreter")
2const cdi = await Cdi.deploy(token.address)
3await cdi.deployed()
4await token.setProxy(cdi.address)
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1console.log("CalldataInterpreter addr:", cdi.address)
2
3// 需要兩個簽署者來驗證額度
4const signers = await ethers.getSigners()
5const signer = signers[0]
6const poorSigner = signers[1]
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1// 轉帳代幣
2const destAddr = "0xf5a6ead936fb47f342bb63e676479bddf26ebe1d"
3const transferTx = {
4  to: cdi.address,
5  data: "0x02" + destAddr.slice(2, 42) + "0100",
6}
7await (await signer.sendTransaction(transferTx)).wait()
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1// 核准與 transferFrom
2const approveTx = {
3  to: cdi.address,
4  data: "0x03" + poorSigner.address.slice(2, 42) + "00FF",
5}
6await (await signer.sendTransaction(approveTx)).wait()
7
8const destAddr2 = "0xE1165C689C0c3e9642cA7606F5287e708d846206"
9
10const transferFromTx = {
11  to: cdi.address,
12  data: "0x04" + signer.address.slice(2, 42) + destAddr2.slice(2, 42) + "00FF",
13}
14await (await poorSigner.sendTransaction(transferFromTx)).wait()
15
16// 檢查 approve / transferFrom 組合是否正確完成
17expect(await token.balanceOf(destAddr2)).to.equal(255)
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