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在Substrate链上跑Solidity ERC20智能合约

2015 年 8 月 20 日

在Substrate链上跑Solidity ERC20智能合约

jasonruan 2020.07.18

1 前言

本实践案例中，我们首先会搭建和启动一条 substrate 链，再通过 MetaMask 这款著名的以太坊钱包浏览器插件，通过自定义 RPC 的方式，接入我们搭建好的 substrate 链。

然后我们会在 remix 这款智能合约在线 IDE 上的完成 ERC20 智能合约的开发、编译、部署、调试。 remix 将通过 Injected Web3 的方式接入我们的 MetaMask 钱包，借助 MetaMask 实现和 substrate 链的交互。

2 前置准备

2.1 substrate链启动

由于 Substrate 的 runtime 没有集成 EVM ，需要使用 Parity 另外一个项目： Frontier 。 Frontier 是 Substrate 的以太坊兼容层。

在这个项目中，增加了 pallet-evm 、 pallet-ethereum 、 rpc-ethereum ，可以最大程度的模拟以太坊的环境，以便可以无缝对接当前以太坊生态里面 DApp 及第三方工具，如 remix 、 metamask 等。

2.1.1 安装

$ git clone git@github.com:paritytech/frontier.git

$ cd frontier

(master)$ git log
commit fcea97281661f0a0a4c28e46edbfb1238043471e
Author: Wei Tang 
Date:   Tue Jul 14 13:25:48 2020 +0200

(master)$ git submodule init
子模组 'vendor/ethereum' (https://github.com/rust-blockchain/ethereum) 已为路径 'vendor/ethereum' 注册
子模组 'vendor/evm' (https://github.com/rust-blockchain/evm) 已为路径 'vendor/evm' 注册
子模组 'vendor/substrate' (https://github.com/paritytech/substrate) 已为路径 'vendor/substrate' 注册

(master)$ git submodule update
正克隆到 'vendor/ethereum'...
处理 delta 中: 100% (930/930), done.
子模组路径 'vendor/ethereum'：检出 '4fdd3c8ac849f91f5352bc7dfc189144a09aac1e'
正克隆到 'vendor/evm'...
子模组路径 'vendor/evm'：检出 '84013f3ea23e436541f409c717134dd1536143de'
正克隆到 'vendor/substrate'...
fatal: 引用不是一个树：b36fc2c849ae0cba434bb3ce82e0a4dda5bcbe7a
无法在子模组路径 'vendor/substrate' 中检出 'b36fc2c849ae0cba434bb3ce82e0a4dda5bcbe7a'

# 获取子模块有报错，单独clone substrate工程来解决
$ cd vendor
$ /bin/rm -rf substrate
$ git clone git@github.com:paritytech/substrate.git

# 注意：这里不能切换到最新的tag（v2.0.0-rc4），编译会报错，采用当前最新的master分支，可以正常编译frontier
[Jason@RUAN:~/frontier/vendor/substrate] (master)$ git log
commit 9b5a9cb9056f8ab049837d30b500fca78a6c362c
Author: Shawn Tabrizi 
Date:   Thu Jul 16 02:21:15 2020 +0200

2.1.2 添加个人账号

在substrate frontier链的创世配置里面，内建我们在MetaMask上的自有账号，并初始化配置上足够的ETH数量，以便我们开发测试的需要。

  • 拷贝个人测试账号地址

    0x888a0bF014d1D6334002261BaC34a16f5Ce963ac

  • 修改 frontier/template/node/src/chain_spec.rs ，添加以下内容： 
+  29 use std::str::FromStr;

! 141         let built_in_evm_account =
! 142             H160::from_str("888a0bF014d1D6334002261BaC34a16f5Ce963ac").unwrap();
! 143         let mut evm_accounts = BTreeMap::new();
! 144         //let ten: u128 = 10;
! 145         evm_accounts.insert(
! 146             built_in_evm_account,
! 147             evm::GenesisAccount {
! 148                 nonce: 0.into(),
! 149                 balance: (2018030320150719 as u128 * 10_u128.pow(18)).into(),    // 设置账户初始ETH余额，注意ETH有18位小数
! 150                 storage: BTreeMap::new(),                                 
! 151                 code: WASM_BINARY.to_vec(),
! 152             },  
! 153         );

2.1.3 编译

$ cargo build --release

2.1.4 运行

(master)$ ./target/release/frontier-template-node purge-chain --dev
Are you sure to remove "/root/.local/share/frontier-template-node/chains/dev/db"? [y/N]: y
"/root/.local/share/frontier-template-node/chains/dev/db" did not exist.

(master)$ ./target/release/frontier-template-node  --dev --ws-external --rpc-external --rpc-cors=all
2020-07-18 22:59:28 Substrate Node
2020-07-18 22:59:28 :v:  version 2.0.0-dev-fcea972-x86_64-linux-gnu
2020-07-18 22:59:28 :heart:  by Parity Technologies , 2017-2020
2020-07-18 22:59:28 :clipboard: Chain specification: Development
2020-07-18 22:59:28     Node name: stimulating-hand-5352
2020-07-18 22:59:28 :bust_in_silhouette: Role: AUTHORITY
2020-07-18 22:59:28 :floppy_disk: Database: RocksDb at /root/.local/share/frontier-template-node/chains/dev/db
2020-07-18 22:59:28 ⛓  Native runtime: node-frontier-template-1 (node-frontier-template-1.tx1.au1)
2020-07-18 22:59:28 :hammer: Initializing Genesis block/state (state: 0x1e15…857d, header-hash: 0xa26e…22df)
2020-07-18 22:59:28 :older_man: Loading GRANDPA authority set from genesis on what appears to be first startup.
2020-07-18 22:59:29 ⏱  Loaded block-time = 6000 milliseconds from genesis on first-launch
2020-07-18 22:59:29 :package: Highest known block at #0
2020-07-18 22:59:29 Using default protocol ID "sup" because none is configured in the chain specs
2020-07-18 22:59:29     Local node identity is: 12D3KooWMgcWheT7cvvpaaKmqNLVPRpAkGLR9V1M7pfs43DxZU6c (legacy representation: QmRN3jaSxZV5dMk1P5tm1CB9oud8pU8SGZvrUFfuS9dNMQ)
2020-07-18 22:59:29 :part_alternation_mark: Prometheus server started at 127.0.0.1:9615
2020-07-18 22:59:30 :raised_hands: Starting consensus session on top of parent 0xa26e0b7f2abed8a4bcf87ca45d20d7628cf22225dd522385e7b49ee6c30522df
2020-07-18 22:59:30 :gift: Prepared block for proposing at 1 [hash: 0xd3558be2df939b94ba94d82ded332216b0b06a55596d0a61a858aeaf7acc16c4; parent_hash: 0xa26e…22df; extrinsics (1): [0xead1…ac1b]]
2020-07-18 22:59:30 :bookmark: Pre-sealed block for proposal at 1. Hash now 0x8aa38d1228213371249ff83404bd8576e3e0bce6e120f93a9fe08ec2dfdc2d86, previously 0xd3558be2df939b94ba94d82ded332216b0b06a55596d0a61a858aeaf7acc16c4.
2020-07-18 22:59:30 :sparkles: Imported #1 (0x8aa3…2d86)
2020-07-18 22:59:34 :zzz: Idle (0 peers), best: #1 (0x8aa3…2d86), finalized #0 (0xa26e…22df), ⬇ 0 ⬆ 0
2020-07-18 22:59:36 :raised_hands: Starting consensus session on top of parent 0x8aa38d1228213371249ff83404bd8576e3e0bce6e120f93a9fe08ec2dfdc2d86
2020-07-18 22:59:36 :gift: Prepared block for proposing at 2 [hash: 0x570be59726cf2018fab9e7bae77208a990921291fe8164bbc1df253f8142d3f6; parent_hash: 0x8aa3…2d86; extrinsics (1): [0xec7f…0d17]]
2020-07-18 22:59:36 :bookmark: Pre-sealed block for proposal at 2. Hash now 0xe9831c239f29745d79b0e72cc26c0db19ce4d0c7712a32dae4cc60f8ad538551, previously 0x570be59726cf2018fab9e7bae77208a990921291fe8164bbc1df253f8142d3f6.
2020-07-18 22:59:36 :sparkles: Imported #2 (0xe983…8551)

2.2 MetaMask接入frontier链

2.2.1 配置自定义RPC接入

这里 ChainID 填42，源于 runtime 中的定义： 

parameter_types! {
    pub const EVMModuleId: ModuleId = ModuleId(*b"py/evmpa");
    pub const ChainId: u64 = 42; 
}

impl evm::Trait for Runtime {
    type ModuleId = EVMModuleId;
    type FeeCalculator = FixedGasPrice;
    type ConvertAccountId = HashTruncateConvertAccountId;
    type Currency = Balances;
    type Event = Event;
    type Precompiles = (); 
    type ChainId = ChainId;
}

2.2.2 查看账户余额

2.2.3 开启Gas控制高级选项

开启该选项后，以便我们随意配置 gas limit 和 gas price ：

2.3 remix接入MetaMask

  • 使用 Injected Web3 建立与 MetaMask 账号的连接

我们看到我们创建的账号已经成功接入 remix ，接下来，我们便可以进行 ERC20 合约的开发和部署了。

3 合约开发&部署

3.1 智能合约编写

我们要编写两个合约，其中 SafeMath.sol 是一个算数运算防溢出的安全库， xyc.sol 是一个 ERC20 智能合约。

3.1.1 SafeMath.sol

pragma solidity ^0.6.0;

library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b  0, errorMessage);
        uint256 c = a / b;
        return c;
    }

    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

3.1.2 xyc.sol

pragma solidity ^0.6.0;

import "./SafeMath.sol";

abstract contract ERC20 {
   function totalSupply() public virtual view returns (uint256);
   function balanceOf(address owner) public virtual view returns (uint256);
   function transfer(address to, uint256 value) public virtual returns (bool);
   function transferFrom(address from, address to, uint256 value) public virtual returns (bool);
   function approve(address spender, uint256 value) public virtual returns (bool);
   function allowance(address owner, address spender) public virtual view returns (uint256);
   event Transfer(address indexed from, address indexed to, uint256 value);
   event Approval(address indexed owner, address indexed spender, uint256 value);
}

contract xyc is ERC20 {

    using SafeMath for uint256;

    string name = "XuanYuan Coin";
    string symbol = "xyc";
    uint8 decimals;
    uint256 private _totalSupply;
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;

    constructor(uint256 myTotalSupply, uint8 mydecimals) public {
        _totalSupply = myTotalSupply;
        decimals = mydecimals;
        _balances[msg.sender] = myTotalSupply;
    }

   function totalSupply() public override view returns (uint256) {
       return _totalSupply;
   }

   function balanceOf(address _owner) public override view returns (uint256) {
       return _balances[_owner];
   }

   function transfer(address to, uint256 value) public override returns (bool) {
       require(to != address(0), "ERC20 ERROR: transfer from zero address");
       require(value = _balances[to]);

       _balances[msg.sender] = _balances[msg.sender].sub(value);
       _balances[to] = _balances[to].add(value);

       emit Transfer(msg.sender, to, value);

       return true;
   }

   function transferFrom(address from, address to, uint256 value) public override returns (bool) {
       require(to != address(0));
       require(value <= _balances[from]);
       require(value = _balances[to]);

       _balances[from] = _balances[from].sub(value);
       _balances[to] = _balances[to].add(value);
       _allowances[from][msg.sender] = _allowances[from][msg.sender].sub(value);

       emit Transfer(from, to, value);

       return true;
   }

   function approve(address spender, uint256 value) public override returns (bool) {
       require(value <= _balances[msg.sender]);
       _allowances[msg.sender][spender] = value;
       emit Approval(msg.sender, spender, value);
       return true;
   }

   function allowance(address _owner, address spender) public override view returns (uint256) {
       return _allowances[_owner][spender];
   }

   event Transfer(address indexed from, address indexed to, uint256 value);
   event Approval(address indexed owner, address indexed spender, uint256 value);
}

3.2 智能合约编译

智能合约编译成功，接下来我们就将已经开发完成的 Solidity ERC20 智能合约部署到 Substrate 链上。

3.3 智能合约部署

  • 选择要部署的合约，填写构造方法中的发行总量和精度两个参数，点击 transact 按钮

注：当前版本需要在弹出的MetaMask对话框上，设置很大的gas limit值（ 4294967295 ）才能部署成功:(

4 合约功能测试

通过 remix 完成对 ERC20 合约的功能测试。

4.1 查看发行量&余额

可见所有发行代币都归属于合约部署方地址。

4.2 转账测试

  • 给账户2： 0x8A832874304Be72b299C0ED96f22B11311c9051C ，转账1000.00 XYC，查看账户1地址XYC代币数量为：9000.00，符合预期

  • 在MetaMask上添加自定义代币

合约地址： 0xfE2dF1EE3783eBD46481e32d849acB49ec5004Bf

  • 代币发行方地址所剩代币为：9000.00 XYC

  • 代币接收方地址代币数量为：1000.00 XYC

4.3 授权代理转账测试

  • 为账户2转账ETH，用于支付gas费

  • 用户1授权用户2可代理转账的代币数量为2000.00 XYC

  • 查看用户2所能授权转账用户1的XYC代币

| 账号 | 地址 | | ——— | ——————————————– | | Jasonruan | 0x888a0bF014d1D6334002261BaC34a16f5Ce963ac | | Account 2 | 0x8A832874304Be72b299C0ED96f22B11311c9051C | | Account 3 | 0x6Be02d1d3665660d22FF9624b7BE0551ee1Ac91b |

  • 用户2代理用户1给用户3转账2000.00 XYC

成功转账后，查看到用户2所能授权转账用户1的XYC代币数量为0

  • 查看到账户3上XYC代币余额

  • 再次查看账户1上的代币余额

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