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在Substrate链上跑Solidity ERC20智能合约
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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。
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 [email protected]:paritytech/frontier.git $ cd frontier (master)$ git log commit fcea97281661f0a0a4c28e46edbfb1238043471e Author: Wei Tang <[email protected]> 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 [email protected]: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 <[email protected]> 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 <[email protected]>, 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<BlakeTwo256>;
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 <= a, errorMessage);
uint256 c = a - b;
return c;
}
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
if (a == 0) {
return 0;
}
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}
function div(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[msg.sender]);
require(_balances[to] + 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 <= _allowances[from][msg.sender]);
require(_balances[to] + 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
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 [email protected]:paritytech/frontier.git $ cd frontier (master)$ git log commit fcea97281661f0a0a4c28e46edbfb1238043471e Author: Wei Tang <[email protected]> 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 [email protected]: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 <[email protected]> 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 <[email protected]>, 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<BlakeTwo256>;
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 <= a, errorMessage);
uint256 c = a - b;
return c;
}
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
if (a == 0) {
return 0;
}
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}
function div(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[msg.sender]);
require(_balances[to] + 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 <= _allowances[from][msg.sender]);
require(_balances[to] + 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
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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