Gateway 和 Uniswap
gateway通過用ethers(https://github.com/ethers-io/ethers.js)與ETH網絡交互
使用@uniswap/sdk(https://github.com/Uniswap/uniswap-v2-sdk)來實現(xiàn)與uninswap的交互
EthereumService 組件(ethereumService)
ethereum.ts 封裝了調用 ether 庫針對 eth 網絡的操作
getETHBalance從錢包中檢查 ETH 余額
getERC20Balance從合約中檢查 ERC20 的余額
getERC20Allowance檢查 spender 允許從錢包轉移的數(shù)目
approveERC20授權spender從錢包轉移ERC20代幣
deposit給 ERC20 地址轉幣员淫，暫時沒人用這個 api
getERC20TokenAddress獲取 ERC20 代幣地址
getERC20TokenByAddress通過地址獲取 ERC20 代幣
getWallet獲取錢包信息
getTransactionReceipt通過 txHash 獲得交易信息
Uniswap 組件(uni)
uniswap.js 封裝了針對 uniswap 的操作荡碾，比如下單命贴，獲取交易對等操作
fetch_route: 獲取交易路徑精盅，主要在獲取兌換價格priceSwapIn時候使用吞获，因為有的幣可能需要經過>1次兌換才能換到目標幣種渔嚷，這種情況下就需要獲取交易路徑。
extend_update_pairs: 在獲取兌換價格priceSwapIn的時候會使用媳握，用來更新交換幣對的擴展的屬性碱屁。
update_pairs: 定時執(zhí)行更新維護幣對列表，主要只維護幣對蛾找，擴展信息交由獲取價格時候調用 extend_update_pairs實現(xiàn)娩脾。
priceSwapIn:獲取換入幣種的價格，賣出幣種時候使用腋粥。
priceSwapOut:獲取換出幣種的價格晦雨，買入幣種的時候使用架曹。
兩個函數(shù)結構相似隘冲，區(qū)分的是 base 和 quote 幣種要互換位置。買入quote數(shù)目->預計付出base數(shù)目->成交->實際付出和預計數(shù)量不一定一樣绑雄，賣出quote數(shù)目->預計獲得base數(shù)目->成交->實際獲得和預計數(shù)量不一定一樣
swapExactIn:在這個函數(shù)里面會實際調用 eth 合約實現(xiàn)交易展辞，如果要賣出幣種調用的是這個函數(shù)
swapExactOut:在這個函數(shù)里面會實際調用 eth 合約實現(xiàn)交易，如果要買入幣種調用的是這個函數(shù)
其實兩個函數(shù)并沒有什么本質區(qū)別站在不同的角度上 swapIn 也是一種 swapOut万牺，代碼也是一樣的只是變量交換了位置罗珍。
授權
授權幣種
141@ethereum.ts
const wallet = ethereumService.getWallet(req.body.privateKey);
// Getting token info
const tokenContractInfo = ethereumService.getERC20TokenAddress(
req.body.token
);
const tokenAddress = tokenContractInfo.address;
const gasPrice = req.body.gasPrice || ethereumGasService.getGasPrice();
let amount = ethers.constants.MaxUint256;
if (req.body.amount) {
amount = ethers.utils.parseUnits(
req.body.amount,
tokenContractInfo.decimals
);
}
// call approve function
let approval;
try {
approval = await ethereumService.approveERC20(
wallet,
spender,
tokenAddress,
amount,
gasPrice
);
} catch (err) {
approval = err;
}
......
175@ethereums.ts
const contract = new Contract(tokenAddress, abi.ERC20Abi, wallet);
contract.approve(spender, amount, {
gasPrice: gasPrice * 1e9,
// fixate gas limit to prevent overwriting
gasLimit: this.config.approvalGasLimit,
});
獲取錢包授權的數(shù)量
//88@ethereums.ts
const wallet = ethereumService.getWallet(req.body.privateKey);
approvals[symbol] = await ethereumService.getERC20Allowance(
wallet,
spender,
address,
decimals
);
const contract = new Contract(tokenAddress, abi.ERC20Abi, this.provider);
const allowance = await contract.allowance(wallet.address, spender);
獲取 swap 價格
//166@uniswap.js
//還有一個priceSwapIn 類似
async priceSwapOut(tokenIn, tokenOut, tokenOutAmount) {
await this.extend_update_pairs([tokenIn, tokenOut]);
const tOut = this.tokenList[tokenOut];
const tIn = this.tokenList[tokenIn];
const tokenAmountOut = new uni.TokenAmount(
tOut,
ethers.utils.parseUnits(tokenOutAmount, tOut.decimals)
);
//先查詢本地緩存
if (this.pairs.length === 0) {
const route = await this.fetch_route(tIn, tOut);
const trade = uni.Trade.exactOut(route, tokenAmountOut);
if (trade !== undefined) {
const expectedAmount = trade.maximumAmountIn(this.allowedSlippage);
this.cachedRoutes[tIn.symbol + tOut.Symbol] = trade;
return { trade, expectedAmount };
}
return;
}
// 最大可以換出的數(shù)目
let trade = uni.Trade.bestTradeExactOut(
this.pairs,
this.tokenList[tokenIn],
tokenAmountOut,
{ maxHops: 5 }
)[0];
if (trade === undefined) {
trade = this.cachedRoutes[tIn.symbol + tOut.Symbol];
} else {
this.cachedRoutes[tIn.symbol + tOut.Symbol] = trade;
}
const expectedAmount = trade.maximumAmountIn(this.allowedSlippage);
return { trade, expectedAmount };
}
SWAP
// 254@uniswap.js
//還有一個swapExactIn 類似
async swapExactOut(wallet, trade, tokenAddress, gasPrice) {
const result = uni.Router.swapCallParameters(trade, {
ttl: TTL,
recipient: wallet.address,
allowedSlippage: this.allowedSlippage,
});
const contract = new ethers.Contract(
this.router,
proxyArtifact.abi,
wallet
);
//真正調用合約的地方
const tx = await contract[result.methodName](...result.args, {
gasPrice: gasPrice * 1e9,
gasLimit: GAS_LIMIT,
value: result.value,
});
debug(`Tx Hash: ${tx.hash}`);
return tx;
}
交易記錄
//202@ethereum.
//json-rpc-provider
async perform(method: string, params: any): Promise<any> {
const args = this.prepareRequest(method, params);
if (args == null) {
logger.throwError(method + " not implemented", Logger.errors.NOT_IMPLEMENTED, { operation: method });
}
try {
return await this.send(args[0], args[1])
} catch (error) {
return checkError(method, error, params);
}
}
...
send(method: string, params: Array<any>): Promise<any> {
this.emit("debug", {
action: "request",
request: deepCopy(request),
provider: this
});
}
emit(eventName: EventType, ...args: Array<any>): boolean {
let result = false;
let stopped: Array<Event> = [ ];
let eventTag = getEventTag(eventName);
this._events = this._events.filter((event) => {
if (event.tag !== eventTag) { return true; }
setTimeout(() => {
event.listener.apply(this, args);
}, 0);
result = true;
if (event.once) {
stopped.push(event);
return false;
}
return true;
});
stopped.forEach((event) => { this._stopEvent(event); });
return result;
}
eth 錢包余額
//34@ethereum.ts
const wallet: ethers.Wallet = ethereumService.getWallet(
req.body.privateKey || ''
);
for (const symbol of JSON.parse(req.body.tokenList)) {
const tokenContractInfo = ethereumService.getERC20TokenAddress(symbol);
if (!tokenContractInfo) {
continue;
}
tokenContractList[symbol] = tokenContractInfo;
}
// Getting user balancers
const balances: Record<string, string> = {};
balances.ETH = await ethereumService.getETHBalance(wallet);
await Promise.all(
Object.keys(tokenContractList).map(async (symbol) => {
if (tokenContractList[symbol] !== undefined) {
const address = tokenContractList[symbol].address;
const decimals = tokenContractList[symbol].decimals;
balances[symbol] = await ethereumService.getERC20Balance(
wallet,
address,
decimals
);
} else {
logger.error(`Token contract info for ${symbol} not found`);
}
})
);
