使用Ink!开发Substrate ERC20智能合约

本文参考官方教程 ,带你上手使用Ink!开发Substrate ERC20智能合约

# 使用Ink!开发Substrate ERC20智能合约 *jasonruan 2020.07.14* ## 1 环境搭建 ### 1.1 安装Substrate节点 ```bash $ git clone git@github.com:paritytech/substrate.git $ cd substrate (master)$ git checkout -b v2.0.0-rc4 v2.0.0-rc4 切换到一个新分支 'v2.0.0-rc4' (v2.0.0-rc4)$ cargo build --release ``` ### 1.2 安装cargo contract插件 - 安装命令 ```bash $ cargo install cargo-contract --vers 0.6.1 --force ``` - 帮助手册 ```bash $ cargo contract --help cargo-contract 0.6.1 Utilities to develop Wasm smart contracts USAGE: cargo contract <SUBCOMMAND> OPTIONS: -h, --help Prints help information -V, --version Prints version information SUBCOMMANDS: new Setup and create a new smart contract project build Compiles the smart contract generate-metadata Generate contract metadata artifacts test Test the smart contract off-chain help Prints this message or the help of the given subcommand(s) ``` ## 2 ERC20合约介绍 ### 2.1 什么是ERC20标准 ERC20 通证标准(ERC20 Token Standard)是通过以太坊创建通证时的一种规范。按照 ERC20 的规范可以编写一个智能合约,创建“可互换通证”。它并非强制要求,但遵循这个标准,所创建的通证可以与众多交易所、钱包等进行交互,它现在已被行业普遍接受。 ERC20定义了一些标准的接口函数:`balanceOf` 、 `totalSupply` 、`transfer` 、`transferFrom` 、`approve`和`allowance` 。 以及一些可选的字段,例如通证名称、符号以及小数保留位数等。 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/BWJNaa235f0d0de6b250f.png) 详见:https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md ### 2.2 ERC20接口 ```js contract ERC20 { function totalSupply() constant returns (uint theTotalSupply); function balanceOf(address _owner) constant returns (uint balance); function transfer(address _to, uint _value) returns (bool success); function transferFrom(address _from, address _to, uint _value) returns (bool success); function approve(address _spender, uint _value) returns (bool success); function allowance(address _owner, address _spender) constant returns (uint remaining); event Transfer(address indexed _from, address indexed _to, uint _value); event Approval(address indexed _owner, address indexed _spender, uint _value); } ``` - 功能介绍: | 函数名 | 功能 | | -------------- | ------------------------------------------------------------ | | totalSupply | 返回存在于流通中的通证(Token)总量 | | balanceOf | 返回指定账户地址的通证余额 | | transfer | 让调用方将指定数量的通证发送到另一个地址,即转账 | | transferFrom | 允许智能合约自动执行转账流程并代表所有者发送给定数量的通证 | | approve | 调用方授权给定的地址可以从其地址中提款 | | allowance | 返回被允许转移的余额数量 | | event Transfer | 事件通知,当token被转移时,**必须**调用触发,类似回调,当事件发生时,会得到通知 | | event Approval | 事件通知,当任何成功调用`approve`后,**必须**调用触发 | ## 3 ERC20合约开发 ### 3.1 创建合约工程 执行命令后,会生成2个文件,其中`lib.rs`会包括一些基础框架,我们可以在此基础上开发我们的合约。 ```bash $ cargo contract new erc20 Created contract erc20 $ tree erc20/ erc20/ ├── Cargo.toml └── lib.rs ``` ### 3.2 合约存储创建 ```rust #[ink(storage)] struct Erc20 { /// 代币发行总量 total_supply: storage::Value<Balance>, /// 用户及余额映射 balances: storage::HashMap<AccountId, Balance>, } ``` ### 3.3 合约构造方法创建 ```rust #[ink(constructor)] fn new(&mut self, initial_supply: Balance) { // 获取合约创建者 let caller = self.env().caller(); // 设置发行总量 self.total_supply.set(initial_supply); // 合约创建者拥有所有发行代币 self.balances.insert(caller, initial_supply); } ``` ### 3.4 合约接口方法创建 #### (1)查询代币发行总量接口 ```rust #[ink(message)] fn total_supply(&self) -> Balance { *self.total_supply } ``` #### (2)查询用户代币余额接口 ```rust #[ink(message)] fn balance_of(&self, owner: AccountId) -> Balance { self.balance_of_or_zero(&owner) } // 工具方法:若用户未被初始化,代币余额置为0 fn balance_of_or_zero(&self, owner: &AccountId) -> Balance { *self.balances.get(owner).unwrap_or(&0) ``` #### (3)转账接口 ```rust #[ink(message)] fn transfer(&mut self, to: AccountId, value: Balance) -> bool { // 获取合约接口调用者地址 let from = self.env().caller(); // 给接收地址转出指定金额代币 self.transfer_from_to(from, to, value) } fn transfer_from_to(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool { // 获取合约调用者账户余额 let from_balance = self.balance_of_or_zero(&from); if from_balance < value { return false } // 获取合约接受者账户余额(代币接收者账户可能未被初始化,通过此方法将其余额初始化为0) let to_balance = self.balance_of_or_zero(&to); // 发送者余额减少指定数量 self.balances.insert(from, from_balance - value); // 接收者余额增加指定数量 self.balances.insert(to, to_balance + value); true } ``` 我们注意到,在进行余额的增减时,并未像以太坊的`solidity`智能合约,使用额外的`SafeMath`接口,这是因为`ink! `提供了内置防溢出保护,通过在`Cargo.toml` 配置文件中,添加如下配置来提供该安全机制: > ```toml > [profile.release] > panic = "abort" <-- Panics shall be treated as aborts: reduces binary size > lto = true <-- enable link-time-optimization: more efficient codegen > opt-level = "z" <-- Optimize for small binary output > overflow-checks = true <-- Arithmetic overflow protection > ``` #### (4)授权转账——授权接口 通过授权转账,调用方可以授权指定账户,从其地址中安全的消费指定数量的代币。 > 需完善合约存储: > > ```rust > #[ink(storage)] > struct Erc20 { > ...... > // (代币所有者, 代币授权使用者) -> 代币授权使用者可支配余额 > allowances: storage::HashMap<(AccountId, AccountId), Balance>, > } > ``` ```rust #[ink(message)] fn approve(&mut self, spender: AccountId, value: Balance) -> bool { let owner = self.env().caller(); // 代币所有者(owner)授权代币使用者(spender)可支配余额(value) self.allowances.insert((owner, spender), value); true } ``` #### (5)授权转账——余额查询 获取代币授权使用者剩余被允许转移的代币数量。 ```rust #[ink(message)] fn allowance(&self, owner: AccountId, spender: AccountId) -> Balance { self.allowance_of_or_zero(&owner, &spender) } ``` #### (6)授权转账——转账接口 允许智能合约自动执行转账流程并代表所有者发送给定数量的代币 ```rust #[ink(message)] fn transfer_from(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool { let caller = self.env().caller(); let allowance = self.allowance_of_or_zero(&from, &caller); if allowance < value { return false } self.allowances.insert((from, caller), allowance - value); self.transfer_from_to(from, to, value) } fn allowance_of_or_zero(&self, owner: &AccountId, spender: &AccountId) -> Balance { *self.allowances.get(&(*owner, *spender)).unwrap_or(&0) } ``` ### 3.5 合约事件创建 - 事件定义 ```rust #[ink(event)] struct Transfer { #[ink(topic)] from: Option<AccountId>, #[ink(topic)] to: Option<AccountId>, #[ink(topic)] value: Balance, } #[ink(event)] struct Approval { #[ink(topic)] owner: AccountId, #[ink(topic)] spender: AccountId, #[ink(topic)] value: Balance, } ``` - 合约构造事件 ```rust self.env().emit_event(Transfer { from: None, to: Some(caller), value: initial_supply, }); ``` - 转账事件 ```rust self.env().emit_event(Transfer { from: Some(from), to: Some(to), value, }); ``` - 授权事件 ```rust self.env().emit_event(Approval { owner, spender, value, }); ``` ### 3.6 单元测试用例编写 ```rust #[test] fn new_works() { let contract = Erc20::new(777); assert_eq!(contract.total_supply(), 777); } #[test] fn balance_works() { let contract = Erc20::new(100); assert_eq!(contract.total_supply(), 100); assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100); assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 0); } #[test] fn transfer_works() { let mut contract = Erc20::new(100); assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100); assert!(contract.transfer(AccountId::from([0x0; 32]), 10)); assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 10); assert!(!contract.transfer(AccountId::from([0x0; 32]), 100)); } #[test] fn transfer_from_works() { let mut contract = Erc20::new(100); assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100); contract.approve(AccountId::from([0x1; 32]), 20); contract.transfer_from(AccountId::from([0x1; 32]), AccountId::from([0x0; 32]), 10); assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 10); } ``` > 跑测试用例: > > ```bash > $ cargo +nightly test > ``` > > ![image.png](https://img.learnblockchain.cn/attachments/2020/07/98pf7dPY5f0d0eb89c560.png) ### 3.7 完整代码 ```rust #![cfg_attr(not(feature = "std"), no_std)] use ink_lang as ink; #[ink::contract(version = "0.1.0")] mod erc20 { use ink_core::storage; #[ink(storage)] struct Erc20 { /// The total supply. total_supply: storage::Value<Balance>, /// The balance of each user. balances: storage::HashMap<AccountId, Balance>, /// Approval spender on behalf of the message's sender. allowances: storage::HashMap<(AccountId, AccountId), Balance>, } #[ink(event)] struct Transfer { #[ink(topic)] from: Option<AccountId>, #[ink(topic)] to: Option<AccountId>, #[ink(topic)] value: Balance, } #[ink(event)] struct Approval { #[ink(topic)] owner: AccountId, #[ink(topic)] spender: AccountId, #[ink(topic)] value: Balance, } impl Erc20 { #[ink(constructor)] fn new(&mut self, initial_supply: Balance) { let caller = self.env().caller(); self.total_supply.set(initial_supply); self.balances.insert(caller, initial_supply); self.env().emit_event(Transfer { from: None, to: Some(caller), value: initial_supply, }); } #[ink(message)] fn total_supply(&self) -> Balance { *self.total_supply } #[ink(message)] fn balance_of(&self, owner: AccountId) -> Balance { self.balance_of_or_zero(&owner) } #[ink(message)] fn approve(&mut self, spender: AccountId, value: Balance) -> bool { let owner = self.env().caller(); self.allowances.insert((owner, spender), value); self.env().emit_event(Approval { owner, spender, value, }); true } #[ink(message)] fn allowance(&self, owner: AccountId, spender: AccountId) -> Balance { self.allowance_of_or_zero(&owner, &spender) } #[ink(message)] fn transfer_from(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool { let caller = self.env().caller(); let allowance = self.allowance_of_or_zero(&from, &caller); if allowance < value { return false } self.allowances.insert((from, caller), allowance - value); self.transfer_from_to(from, to, value) } #[ink(message)] fn transfer(&mut self, to: AccountId, value: Balance) -> bool { let from = self.env().caller(); self.transfer_from_to(from, to, value) } fn transfer_from_to(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool { let from_balance = self.balance_of_or_zero(&from); if from_balance < value { return false } let to_balance = self.balance_of_or_zero(&to); self.balances.insert(from, from_balance - value); self.balances.insert(to, to_balance + value); self.env().emit_event(Transfer { from: Some(from), to: Some(to), value, }); true } fn balance_of_or_zero(&self, owner: &AccountId) -> Balance { *self.balances.get(owner).unwrap_or(&0) } fn allowance_of_or_zero(&self, owner: &AccountId, spender: &AccountId) -> Balance { *self.allowances.get(&(*owner, *spender)).unwrap_or(&0) } } #[cfg(test)] mod tests { use super::*; #[test] fn new_works() { let contract = Erc20::new(777); assert_eq!(contract.total_supply(), 777); } #[test] fn balance_works() { let contract = Erc20::new(100); assert_eq!(contract.total_supply(), 100); assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100); assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 0); } #[test] fn transfer_works() { let mut contract = Erc20::new(100); assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100); assert!(contract.transfer(AccountId::from([0x0; 32]), 10)); assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 10); assert!(!contract.transfer(AccountId::from([0x0; 32]), 100)); } #[test] fn transfer_from_works() { let mut contract = Erc20::new(100); assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100); contract.approve(AccountId::from([0x1; 32]), 20); contract.transfer_from(AccountId::from([0x1; 32]), AccountId::from([0x0; 32]), 10); assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 10); } } } ``` ## 4 ERC20合约部署 ### 4.1 启动substrate链 ```bash [Jason@RUAN:~/Blockchain/substrate] (v2.0.0-rc4)$ ./target/release/substrate purge-chain --dev Are you sure to remove "/root/.local/share/substrate/chains/dev/db"? [y/N]: y "/root/.local/share/substrate/chains/dev/db" did not exist. [Jason@RUAN:~/Blockchain/substrate] (v2.0.0-rc4)$ ./target/release/substrate --dev --ws-external --rpc-external --rpc-cors=all 2020-07-13 23:07:17 Substrate Node 2020-07-13 23:07:17 ️ version 2.0.0-rc4-00768a1-x86_64-linux-gnu 2020-07-13 23:07:17 ️ by Parity Technologies <admin@parity.io>, 2017-2020 2020-07-13 23:07:17 Chain specification: Development 2020-07-13 23:07:17 Node name: ill-hen-8567 2020-07-13 23:07:17 Role: AUTHORITY 2020-07-13 23:07:17 Database: RocksDb at /root/.local/share/substrate/chains/dev/db 2020-07-13 23:07:17 Native runtime: node-254 (substrate-node-0.tx1.au10) 2020-07-13 23:07:17 new validator set of size 1 has been elected via ElectionCompute::OnChain for era 0 2020-07-13 23:07:17 Initializing Genesis block/state (state: 0xc720…bb8a, header-hash: 0x6ea2…1245) 2020-07-13 23:07:17 Loading GRANDPA authority set from genesis on what appears to be first startup. 2020-07-13 23:07:17 ⏱ Loaded block-time = 3000 milliseconds from genesis on first-launch 2020-07-13 23:07:17 Creating empty BABE epoch changes on what appears to be first startup. 2020-07-13 23:07:17 Highest known block at #0 2020-07-13 23:07:17 Using default protocol ID "sup" because none is configured in the chain specs 2020-07-13 23:07:17 Local node identity is: 12D3KooWQUQtujJ5SGCdCcheuExioC81R5W4E3RFGhmhx3MT8iqy (legacy representation: QmX71wUqWKy7FQX8PEHKoQLaiBLLTfK8TL25mFXxKhMWGw) 2020-07-13 23:07:17 〽 Prometheus server started at 127.0.0.1:9615 2020-07-13 23:07:17 Starting BABE Authorship worker 2020-07-13 23:07:18 Starting consensus session on top of parent 0x6ea2a97a8da973976a82f053a8b909aff5e0659ca6d51b6c9d6947b4dc3d1245 2020-07-13 23:07:18 Prepared block for proposing at 1 [hash: 0x3b99b664d0a21fbc72bfed709700b5bba05564c8d62e9ddd677412896f25de31; parent_hash: 0x6ea2…1245; extrinsics (1): [0xdcda…fb8d]] 2020-07-13 23:07:18 Pre-sealed block for proposal at 1. Hash now 0x3081484a5cbe82a9b4a4aea4d360fd69219a43d18182c6fd297e2ffac71feff2, previously 0x3b99b664d0a21fbc72bfed709700b5bba05564c8d62e9ddd677412896f25de31. 2020-07-13 23:07:18 New epoch 0 launching at block 0x3081…eff2 (block slot 531550946 >= start slot 531550946). 2020-07-13 23:07:18 Next epoch starts at slot 531551146 2020-07-13 23:07:18 Imported #1 (0x3081…eff2) 2020-07-13 23:07:21 Starting consensus session on top of parent 0x3081484a5cbe82a9b4a4aea4d360fd69219a43d18182c6fd297e2ffac71feff2 2020-07-13 23:07:21 Prepared block for proposing at 2 [hash: 0x346204e0b46b86dc4ec85b18cf2fdf0f0e818b24208e56217e6f44c135e3aef3; parent_hash: 0x3081…eff2; extrinsics (1): [0xfdbb…bdd0]] 2020-07-13 23:07:21 Pre-sealed block for proposal at 2. Hash now 0x906f64c7a6139ad0819f6c31d776404573e72f3f155bab486a9aeca7c89df810, previously 0x346204e0b46b86dc4ec85b18cf2fdf0f0e818b24208e56217e6f44c135e3aef3. 2020-07-13 23:07:21 Imported #2 (0x906f…f810) ``` ### 4.2 合约编译 ```bash $ cargo contract build [1/4] Collecting crate metadata [2/4] Building cargo project Finished release [optimized] target(s) in 0.05s [3/4] Post processing wasm file [4/4] Optimizing wasm file wasm-opt is not installed. Install this tool on your system in order to reduce the size of your contract's Wasm binary. See https://github.com/WebAssembly/binaryen#tools Your contract is ready. You can find it here: ./erc20/target/erc20.wasm ``` ### 4.3 metadata生成 > 以便通过`polkadot.js.org`与合约进行交互 ```bash $ cargo contract generate-metadata Generating metadata Updating git repository `https://github.com/paritytech/ink` Updating crates.io index Updating git repository `https://github.com/type-metadata/type-metadata.git` Finished release [optimized] target(s) in 3.38s Running `target/release/abi-gen` Your metadata file is ready. You can find it here: ./erc20/target/metadata.json ``` ### 4.4 上传WASM ![image.png](https://img.learnblockchain.cn/attachments/2020/07/MNwQwaBw5f0d10bb453c7.png) ![image.png](https://img.learnblockchain.cn/attachments/2020/07/lQjwCUVl5f0d10c83ca79.png) ![image.png](https://img.learnblockchain.cn/attachments/2020/07/dNONxJ755f0d10df22e36.png) ### 4.5 部署合约 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/NfUVeMeb5f0d10e997416.png) ![image.png](https://img.learnblockchain.cn/attachments/2020/07/TF6oAcmM5f0d10fed7a96.png) ![image.png](https://img.learnblockchain.cn/attachments/2020/07/i3jkvq0r5f0d110c3c5dc.png) ## 5 ERC20合约执行 ### 5.1 执行合约 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/Ks2Vt2Hy5f0d113cb290a.png) ![image.png](https://img.learnblockchain.cn/attachments/2020/07/TuMyBzGd5f0d1130bafc1.png) > 注:右下角开关 > > 打开开关:作为RPC调用发送,只能查看链上状态 > > 关闭开关:作为交易发送,对链上状态有更改 ### 5.2 查询发行总量 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/Z63JoSHn5f0d1149842ba.png) ### 5.3 查询Alice账户余额 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/dQpYpmVh5f0d1164cea63.png) ### 5.4 Alice给Bob转账1000 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/2LROoOrG5f0d11722c42d.png) ### 5.5 分别查询Alice和Bob余额 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/duPZJCBf5f0d11978b00b.png) ### 5.6 Alice授权Eve可以消费自己的2000代币 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/ipddMgA85f0d11ab43e31.png) ### 5.7 Eve给Ferdie转账Alice的500代币 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/kPFLLmlo5f0d11b6e014d.png) ### 5.8 查看到Ferdie的代币数 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/BrbGqu9f5f0d11cfe3e44.png) ### 5.9 查看Eve剩余Alice的授权额度 ![image.png](https://img.learnblockchain.cn/attachments/2020/07/wbd9snLb5f0d11e536902.png) # 6 参考资料 https://substrate.dev/substrate-contracts-workshop/#/

使用Ink!开发Substrate ERC20智能合约

jasonruan 2020.07.14

1 环境搭建

1.1 安装Substrate节点

$ git clone git@github.com:paritytech/substrate.git
$ cd substrate
(master)$ git checkout -b v2.0.0-rc4 v2.0.0-rc4
切换到一个新分支 'v2.0.0-rc4'
(v2.0.0-rc4)$ cargo build --release

1.2 安装cargo contract插件

  • 安装命令
$ cargo install cargo-contract --vers 0.6.1 --force
  • 帮助手册
$ cargo contract --help
cargo-contract 0.6.1
Utilities to develop Wasm smart contracts

USAGE:
    cargo contract &lt;SUBCOMMAND>

OPTIONS:
    -h, --help       Prints help information
    -V, --version    Prints version information

SUBCOMMANDS:
    new                  Setup and create a new smart contract project
    build                Compiles the smart contract
    generate-metadata    Generate contract metadata artifacts
    test                 Test the smart contract off-chain
    help                 Prints this message or the help of the given subcommand(s)

2 ERC20合约介绍

2.1 什么是ERC20标准

ERC20 通证标准(ERC20 Token Standard)是通过以太坊创建通证时的一种规范。按照 ERC20 的规范可以编写一个智能合约,创建“可互换通证”。它并非强制要求,但遵循这个标准,所创建的通证可以与众多交易所、钱包等进行交互,它现在已被行业普遍接受。

ERC20定义了一些标准的接口函数:balanceOftotalSupplytransfertransferFromapproveallowance 。 以及一些可选的字段,例如通证名称、符号以及小数保留位数等。

详见:https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md

2.2 ERC20接口

contract ERC20 {
   function totalSupply() constant returns (uint theTotalSupply);
   function balanceOf(address _owner) constant returns (uint balance);
   function transfer(address _to, uint _value) returns (bool success);
   function transferFrom(address _from, address _to, uint _value) returns (bool success);
   function approve(address _spender, uint _value) returns (bool success);
   function allowance(address _owner, address _spender) constant returns (uint remaining);
   event Transfer(address indexed _from, address indexed _to, uint _value);
   event Approval(address indexed _owner, address indexed _spender, uint _value);
}
  • 功能介绍:
函数名 功能
totalSupply 返回存在于流通中的通证(Token)总量
balanceOf 返回指定账户地址的通证余额
transfer 让调用方将指定数量的通证发送到另一个地址,即转账
transferFrom 允许智能合约自动执行转账流程并代表所有者发送给定数量的通证
approve 调用方授权给定的地址可以从其地址中提款
allowance 返回被允许转移的余额数量
event Transfer 事件通知,当token被转移时,必须调用触发,类似回调,当事件发生时,会得到通知
event Approval 事件通知,当任何成功调用approve后,必须调用触发

3 ERC20合约开发

3.1 创建合约工程

执行命令后,会生成2个文件,其中lib.rs会包括一些基础框架,我们可以在此基础上开发我们的合约。

$ cargo contract new erc20
    Created contract erc20

$ tree erc20/
erc20/
├── Cargo.toml
└── lib.rs

3.2 合约存储创建

    #[ink(storage)]
    struct Erc20 {
        /// 代币发行总量
        total_supply: storage::Value&lt;Balance>,
        /// 用户及余额映射
        balances: storage::HashMap&lt;AccountId, Balance>,
    }

3.3 合约构造方法创建

        #[ink(constructor)]
        fn new(&mut self, initial_supply: Balance) {
            // 获取合约创建者
            let caller = self.env().caller();
            // 设置发行总量
            self.total_supply.set(initial_supply);
            // 合约创建者拥有所有发行代币
            self.balances.insert(caller, initial_supply);
        }

3.4 合约接口方法创建

(1)查询代币发行总量接口

        #[ink(message)]
        fn total_supply(&self) -> Balance {
            *self.total_supply
        }

(2)查询用户代币余额接口

        #[ink(message)]
        fn balance_of(&self, owner: AccountId) -> Balance {
            self.balance_of_or_zero(&owner)
        }

        // 工具方法:若用户未被初始化,代币余额置为0
        fn balance_of_or_zero(&self, owner: &AccountId) -> Balance {
            *self.balances.get(owner).unwrap_or(&0)

(3)转账接口

        #[ink(message)]
        fn transfer(&mut self, to: AccountId, value: Balance) -> bool {
            // 获取合约接口调用者地址
            let from = self.env().caller();
            // 给接收地址转出指定金额代币
            self.transfer_from_to(from, to, value)
        }

        fn transfer_from_to(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool {
            // 获取合约调用者账户余额
            let from_balance = self.balance_of_or_zero(&from);
            if from_balance &lt; value {
                return false
            }
            // 获取合约接受者账户余额(代币接收者账户可能未被初始化,通过此方法将其余额初始化为0)
            let to_balance = self.balance_of_or_zero(&to);
            // 发送者余额减少指定数量
            self.balances.insert(from, from_balance - value);
            // 接收者余额增加指定数量
            self.balances.insert(to, to_balance + value);
            true
        }

我们注意到,在进行余额的增减时,并未像以太坊的solidity智能合约,使用额外的SafeMath接口,这是因为ink!提供了内置防溢出保护,通过在Cargo.toml 配置文件中,添加如下配置来提供该安全机制:

[profile.release]
panic = "abort"           &lt;-- Panics shall be treated as aborts: reduces binary size
lto = true                &lt;-- enable link-time-optimization: more efficient codegen
opt-level = "z"           &lt;-- Optimize for small binary output
overflow-checks = true    &lt;-- Arithmetic overflow protection

(4)授权转账——授权接口

通过授权转账,调用方可以授权指定账户,从其地址中安全的消费指定数量的代币。

需完善合约存储:

    #[ink(storage)]
    struct Erc20 {
        ......
        // (代币所有者, 代币授权使用者) -> 代币授权使用者可支配余额
        allowances: storage::HashMap&lt;(AccountId, AccountId), Balance>,
    }
        #[ink(message)]
        fn approve(&mut self, spender: AccountId, value: Balance) -> bool {
            let owner = self.env().caller();
            // 代币所有者(owner)授权代币使用者(spender)可支配余额(value)
            self.allowances.insert((owner, spender), value);
            true
        }

(5)授权转账——余额查询

获取代币授权使用者剩余被允许转移的代币数量。

        #[ink(message)]
        fn allowance(&self, owner: AccountId, spender: AccountId) -> Balance {
            self.allowance_of_or_zero(&owner, &spender)
        }

(6)授权转账——转账接口

允许智能合约自动执行转账流程并代表所有者发送给定数量的代币

        #[ink(message)]
        fn transfer_from(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool {
            let caller = self.env().caller();
            let allowance = self.allowance_of_or_zero(&from, &caller);
            if allowance &lt; value {
                return false
            }
            self.allowances.insert((from, caller), allowance - value);
            self.transfer_from_to(from, to, value)
        }

        fn allowance_of_or_zero(&self, owner: &AccountId, spender: &AccountId) -> Balance {
            *self.allowances.get(&(*owner, *spender)).unwrap_or(&0)
        }

3.5 合约事件创建

  • 事件定义
    #[ink(event)]
    struct Transfer {
        #[ink(topic)]
        from: Option&lt;AccountId>,
        #[ink(topic)]
        to: Option&lt;AccountId>,
        #[ink(topic)]
        value: Balance,
    }

    #[ink(event)]
    struct Approval {
        #[ink(topic)]
        owner: AccountId,
        #[ink(topic)]
        spender: AccountId,
        #[ink(topic)]
        value: Balance,
    }
  • 合约构造事件
            self.env().emit_event(Transfer {
                from: None,
                to: Some(caller),
                value: initial_supply,
            });
  • 转账事件
            self.env().emit_event(Transfer {
                from: Some(from),
                to: Some(to),
                value,
            });
  • 授权事件
            self.env().emit_event(Approval {
                owner,
                spender,
                value,
            });

3.6 单元测试用例编写

        #[test]
        fn new_works() {
            let contract = Erc20::new(777);
            assert_eq!(contract.total_supply(), 777);
        }

        #[test]
        fn balance_works() {
            let contract = Erc20::new(100);
            assert_eq!(contract.total_supply(), 100);
            assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
            assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 0);
        }

        #[test]
        fn transfer_works() {
            let mut contract = Erc20::new(100);
            assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
            assert!(contract.transfer(AccountId::from([0x0; 32]), 10));
            assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 10);
            assert!(!contract.transfer(AccountId::from([0x0; 32]), 100));
        }

        #[test]
        fn transfer_from_works() {
            let mut contract = Erc20::new(100);
            assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
            contract.approve(AccountId::from([0x1; 32]), 20);
            contract.transfer_from(AccountId::from([0x1; 32]), AccountId::from([0x0; 32]), 10);
            assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 10);
        }

跑测试用例:

$ cargo +nightly test

3.7 完整代码

#![cfg_attr(not(feature = "std"), no_std)]

use ink_lang as ink;

#[ink::contract(version = "0.1.0")]
mod erc20 {
    use ink_core::storage;

    #[ink(storage)]
    struct Erc20 {
        /// The total supply.
        total_supply: storage::Value&lt;Balance>,
        /// The balance of each user.
        balances: storage::HashMap&lt;AccountId, Balance>,
        /// Approval spender on behalf of the message's sender.
        allowances: storage::HashMap&lt;(AccountId, AccountId), Balance>,
    }

    #[ink(event)]
    struct Transfer {
        #[ink(topic)]
        from: Option&lt;AccountId>,
        #[ink(topic)]
        to: Option&lt;AccountId>,
        #[ink(topic)]
        value: Balance,
    }

    #[ink(event)]
    struct Approval {
        #[ink(topic)]
        owner: AccountId,
        #[ink(topic)]
        spender: AccountId,
        #[ink(topic)]
        value: Balance,
    }

    impl Erc20 {
        #[ink(constructor)]
        fn new(&mut self, initial_supply: Balance) {
            let caller = self.env().caller();
            self.total_supply.set(initial_supply);
            self.balances.insert(caller, initial_supply);
            self.env().emit_event(Transfer {
                from: None,
                to: Some(caller),
                value: initial_supply,
            });
        }

        #[ink(message)]
        fn total_supply(&self) -> Balance {
            *self.total_supply
        }

        #[ink(message)]
        fn balance_of(&self, owner: AccountId) -> Balance {
            self.balance_of_or_zero(&owner)
        }

        #[ink(message)]
        fn approve(&mut self, spender: AccountId, value: Balance) -> bool {
            let owner = self.env().caller();
            self.allowances.insert((owner, spender), value);
            self.env().emit_event(Approval {
                owner,
                spender,
                value,
            });
            true
        }

        #[ink(message)]
        fn allowance(&self, owner: AccountId, spender: AccountId) -> Balance {
            self.allowance_of_or_zero(&owner, &spender)
        }

        #[ink(message)]
        fn transfer_from(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool {
            let caller = self.env().caller();
            let allowance = self.allowance_of_or_zero(&from, &caller);
            if allowance &lt; value {
                return false
            }
            self.allowances.insert((from, caller), allowance - value);
            self.transfer_from_to(from, to, value)
        }

        #[ink(message)]
        fn transfer(&mut self, to: AccountId, value: Balance) -> bool {
            let from = self.env().caller();
            self.transfer_from_to(from, to, value)
        }

        fn transfer_from_to(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool {
            let from_balance = self.balance_of_or_zero(&from);
            if from_balance &lt; value {
                return false
            }
            let to_balance = self.balance_of_or_zero(&to);
            self.balances.insert(from, from_balance - value);
            self.balances.insert(to, to_balance + value);
            self.env().emit_event(Transfer {
                from: Some(from),
                to: Some(to),
                value,
            });
            true
        }

        fn balance_of_or_zero(&self, owner: &AccountId) -> Balance {
            *self.balances.get(owner).unwrap_or(&0)
        }

        fn allowance_of_or_zero(&self, owner: &AccountId, spender: &AccountId) -> Balance {
            *self.allowances.get(&(*owner, *spender)).unwrap_or(&0)
        }
    }

    #[cfg(test)]
    mod tests {
        use super::*;

        #[test]
        fn new_works() {
            let contract = Erc20::new(777);
            assert_eq!(contract.total_supply(), 777);
        }

        #[test]
        fn balance_works() {
            let contract = Erc20::new(100);
            assert_eq!(contract.total_supply(), 100);
            assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
            assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 0);
        }

        #[test]
        fn transfer_works() {
            let mut contract = Erc20::new(100);
            assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
            assert!(contract.transfer(AccountId::from([0x0; 32]), 10));
            assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 10);
            assert!(!contract.transfer(AccountId::from([0x0; 32]), 100));
        }

        #[test]
        fn transfer_from_works() {
            let mut contract = Erc20::new(100);
            assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
            contract.approve(AccountId::from([0x1; 32]), 20);
            contract.transfer_from(AccountId::from([0x1; 32]), AccountId::from([0x0; 32]), 10);
            assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 10);
        }
    }
}

4 ERC20合约部署

4.1 启动substrate链

[Jason@RUAN:~/Blockchain/substrate] (v2.0.0-rc4)$ ./target/release/substrate purge-chain --dev
Are you sure to remove "/root/.local/share/substrate/chains/dev/db"? [y/N]: y
"/root/.local/share/substrate/chains/dev/db" did not exist.

[Jason@RUAN:~/Blockchain/substrate] (v2.0.0-rc4)$ ./target/release/substrate  --dev --ws-external --rpc-external --rpc-cors=all
2020-07-13 23:07:17 Substrate Node
2020-07-13 23:07:17 ️  version 2.0.0-rc4-00768a1-x86_64-linux-gnu
2020-07-13 23:07:17 ️  by Parity Technologies &lt;admin@parity.io>, 2017-2020
2020-07-13 23:07:17  Chain specification: Development
2020-07-13 23:07:17   Node name: ill-hen-8567
2020-07-13 23:07:17  Role: AUTHORITY
2020-07-13 23:07:17  Database: RocksDb at /root/.local/share/substrate/chains/dev/db
2020-07-13 23:07:17   Native runtime: node-254 (substrate-node-0.tx1.au10)
2020-07-13 23:07:17  new validator set of size 1 has been elected via ElectionCompute::OnChain for era 0
2020-07-13 23:07:17  Initializing Genesis block/state (state: 0xc720…bb8a, header-hash: 0x6ea2…1245)
2020-07-13 23:07:17  Loading GRANDPA authority set from genesis on what appears to be first startup.
2020-07-13 23:07:17 ⏱  Loaded block-time = 3000 milliseconds from genesis on first-launch
2020-07-13 23:07:17  Creating empty BABE epoch changes on what appears to be first startup.
2020-07-13 23:07:17  Highest known block at #0
2020-07-13 23:07:17 Using default protocol ID "sup" because none is configured in the chain specs
2020-07-13 23:07:17   Local node identity is: 12D3KooWQUQtujJ5SGCdCcheuExioC81R5W4E3RFGhmhx3MT8iqy (legacy representation: QmX71wUqWKy7FQX8PEHKoQLaiBLLTfK8TL25mFXxKhMWGw)
2020-07-13 23:07:17 〽 Prometheus server started at 127.0.0.1:9615
2020-07-13 23:07:17  Starting BABE Authorship worker
2020-07-13 23:07:18  Starting consensus session on top of parent 0x6ea2a97a8da973976a82f053a8b909aff5e0659ca6d51b6c9d6947b4dc3d1245
2020-07-13 23:07:18  Prepared block for proposing at 1 [hash: 0x3b99b664d0a21fbc72bfed709700b5bba05564c8d62e9ddd677412896f25de31; parent_hash: 0x6ea2…1245; extrinsics (1): [0xdcda…fb8d]]
2020-07-13 23:07:18  Pre-sealed block for proposal at 1. Hash now 0x3081484a5cbe82a9b4a4aea4d360fd69219a43d18182c6fd297e2ffac71feff2, previously 0x3b99b664d0a21fbc72bfed709700b5bba05564c8d62e9ddd677412896f25de31.
2020-07-13 23:07:18  New epoch 0 launching at block 0x3081…eff2 (block slot 531550946 >= start slot 531550946).
2020-07-13 23:07:18  Next epoch starts at slot 531551146
2020-07-13 23:07:18  Imported #1 (0x3081…eff2)
2020-07-13 23:07:21  Starting consensus session on top of parent 0x3081484a5cbe82a9b4a4aea4d360fd69219a43d18182c6fd297e2ffac71feff2
2020-07-13 23:07:21  Prepared block for proposing at 2 [hash: 0x346204e0b46b86dc4ec85b18cf2fdf0f0e818b24208e56217e6f44c135e3aef3; parent_hash: 0x3081…eff2; extrinsics (1): [0xfdbb…bdd0]]
2020-07-13 23:07:21  Pre-sealed block for proposal at 2. Hash now 0x906f64c7a6139ad0819f6c31d776404573e72f3f155bab486a9aeca7c89df810, previously 0x346204e0b46b86dc4ec85b18cf2fdf0f0e818b24208e56217e6f44c135e3aef3.
2020-07-13 23:07:21  Imported #2 (0x906f…f810)

4.2 合约编译

$ cargo contract build
 [1/4] Collecting crate metadata
 [2/4] Building cargo project
    Finished release [optimized] target(s) in 0.05s
 [3/4] Post processing wasm file
 [4/4] Optimizing wasm file
wasm-opt is not installed. Install this tool on your system in order to 
reduce the size of your contract's Wasm binary. 
See https://github.com/WebAssembly/binaryen#tools

Your contract is ready. You can find it here:
./erc20/target/erc20.wasm

4.3 metadata生成

以便通过polkadot.js.org与合约进行交互

$ cargo contract generate-metadata
  Generating metadata
    Updating git repository `https://github.com/paritytech/ink`
    Updating crates.io index
    Updating git repository `https://github.com/type-metadata/type-metadata.git`
    Finished release [optimized] target(s) in 3.38s
     Running `target/release/abi-gen`
    Your metadata file is ready.
You can find it here:
./erc20/target/metadata.json

4.4 上传WASM

4.5 部署合约

5 ERC20合约执行

5.1 执行合约

注:右下角开关

打开开关:作为RPC调用发送,只能查看链上状态

关闭开关:作为交易发送,对链上状态有更改

5.2 查询发行总量

5.3 查询Alice账户余额

5.4 Alice给Bob转账1000

5.5 分别查询Alice和Bob余额

5.6 Alice授权Eve可以消费自己的2000代币

5.7 Eve给Ferdie转账Alice的500代币

5.8 查看到Ferdie的代币数

5.9 查看Eve剩余Alice的授权额度

6 参考资料

https://substrate.dev/substrate-contracts-workshop/#/

区块链技术网。

  • 发表于 2020-07-14 10:02
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