我编写了以下合约，以便在平衡器和 uniswapv3 之间执行交叉闪贷。合约尚未完成，但是我遇到了 REENTRANCY 错误，这可能是由我在 receiveFlashLoan 钩子上覆盖套利逻辑的部分引起的。我放置合约，测试文件和测试结果如下：
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@balancer-labs/v2-interfaces/contracts/vault/IVault.sol";
import "@balancer-labs/v2-interfaces/contracts/vault/IFlashLoanRecipient.sol";
import "@uniswap/v3-periphery/contracts/interfaces/ISwapRouter.sol";
contract CrossFlashLoan is IFlashLoanRecipient {
/*///////////////////////////////////////////////////////////////
FLASHLOAN CONSTANTS
//////////////////////////////////////////////////////////////*/
IVault private constant vault = IVault(0xBA12222222228d8Ba445958a75a0704d566BF2C8);//Balancer Vault address on Ethereum Mainnet
/*///////////////////////////////////////////////////////////////
STATE VARIABLES
//////////////////////////////////////////////////////////////*/
/**
* @dev flashloanTokens will be always borrowed tokens and only one token can be borrowed each time
* Only 0th elementh of amount array will be used to determine the amount of loan that will be received
* flashloanTokens array consists of only wrapped ether by default
* while strategyTokens consist of only bal by default
*/
ISwapRouter private UNISWAP_ROUTER = ISwapRouter(0xE592427A0AEce92De3Edee1F18E0157C05861564); // Uniswap Router address on Ethereum Mainnet
address BALANCER_POOL_ADDRESS = 0x9dDE0b1d39d0d2C6589Cde1BFeD3542d2a3C5b11; // Balancer Pool Address
IERC20[] flashLoanTokens=[IERC20(0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2)];
IERC20[] strategyTokens=[IERC20(IERC20(0xba100000625a3754423978a60c9317c58a424e3D))];
uint256[] amount;
/*///////////////////////////////////////////////////////////////
CUSTOM ERRORS
//////////////////////////////////////////////////////////////*/
error zeroAddressDetected();
error onlyOneBorrowingTokenSupported();
error callerIsNotContract();
/*///////////////////////////////////////////////////////////////
EXTERNAL FUNCTIONS
//////////////////////////////////////////////////////////////*/
/**
*
* @param _amount The amount which will be borrowed by caller
*/
function executeFlashLoan(
uint256 _amount
) external{
//check if executor is 0 address
if(msg.sender==address(0)){
revert zeroAddressDetected();
}
uint256[] memory amounts = new uint256[](1);
amounts[0] = _amount ;
vault.flashLoan(this,flashLoanTokens,amounts,abi.encode(msg.sender));
}
// Function to be called by Balancer flash loan
function receiveFlashLoan(
IERC20[] memory tokens,
uint256[] memory amounts,
uint256[] memory feeAmounts,
bytes memory userData
) external override{
// Checks
if(tokens.length!=1){
revert onlyOneBorrowingTokenSupported();
}
if(address(tokens[0])==address(0)){
revert zeroAddressDetected();
}
// Arbitrage Logic
// Ensure proper ERC-20 token handling
address receipient;
(receipient) = abi.decode(userData, (address));
if(receipient == address(0)){
revert zeroAddressDetected();
}
// Effects
// 1. Swap borrowed WETH to BAL on Uniswap V3
tokens[0].approve(address(UNISWAP_ROUTER), amounts[0]);
ISwapRouter.ExactInputSingleParams memory params = ISwapRouter.ExactInputSingleParams({
tokenIn: address(tokens[0]),
tokenOut: address(strategyTokens[0]),
fee: 3000, // 0.3% fee
recipient: address(this),
deadline: block.timestamp,
amountIn: amounts[0],
amountOutMinimum: 0,
sqrtPriceLimitX96: 0
});
UNISWAP_ROUTER.exactInputSingle(params);
// Update state after external call
amounts[0] = strategyTokens[0].balanceOf(address(this));
// 2. Send BAL to Balancer Pool
strategyTokens[0].approve(address(vault), amounts[0]);
// 3. Swap BAL to WETH back on BalancerV2 then Repay the Loan
vault.swap(
IVault.SingleSwap(
bytes32(abi.encodePacked(BALANCER_POOL_ADDRESS)),
IVault.SwapKind.GIVEN_OUT,
IAsset(address(strategyTokens[0])),
IAsset(address(tokens[0])),
amounts[0],
""
),
IVault.FundManagement(
address(this),
true,
payable(BALANCER_POOL_ADDRESS),
true
),
amounts[0] + feeAmounts[0],
15 minutes
);
// Interactions
// Send funds to EOA (externally owned account)
amounts[0] = flashLoanTokens[0].balanceOf(address(this));
flashLoanTokens[0].approve(receipient,amounts[0]);
tokens[0].transferFrom(address(this),receipient, amounts[0]);
}
/*///////////////////////////////////////////////////////////////
VIEW FUNCTIONS
//////////////////////////////////////////////////////////////*/
function FlashloanToken() external view returns(address){
return address(flashLoanTokens[0]);
}
function StrategyToken() external view returns(address){
return address(strategyTokens[0]);
}
}
import { expect } from "chai";
import { ethers } from "hardhat"
describe("FlashLoan Test",()=>{
let FlashLoan:any,flashloan:any;
before("Deploy Contract",async()=>{
const [deployer] = await ethers.getSigners();
FlashLoan = await ethers.getContractFactory("CrossFlashLoan",deployer);
flashloan = await FlashLoan.deploy();
})
it("Default flashloan token is wrapped ether",async()=>{
let [owner]= await ethers.getSigners()
expect(await flashloan.connect(owner).FlashloanToken()).is.eq('0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2');
})
it("Default strategy Token is balancer",async()=>{
let [owner]= await ethers.getSigners()
expect(await flashloan.connect(owner).StrategyToken()).is.eq('0xba100000625a3754423978a60c9317c58a424e3D');
})
it("Execute flashloan",async()=>{
let [owner]= await ethers.getSigners()
expect(await flashloan.connect(owner).executeFlashLoan(ethers.parseEther('1')));
})
})
` ✔ Default flashloan token is wrapped ether
✔ Default strategy Token is balancer
1) Execute flashloan
2 passing (5s)
1 failing
1) FlashLoan Test
Execute flashloan:
Error: VM Exception while processing transaction: reverted with reason string 'BAL#400'
at <UnrecognizedContract>.<unknown> (0xba12222222228d8ba445958a75a0704d566bf2c8)
at CrossFlashLoan.receiveFlashLoan (contracts/Flashloan.sol:99)
at <UnrecognizedContract>.<unknown> (0xba12222222228d8ba445958a75a0704d566bf2c8)
at CrossFlashLoan.executeFlashLoan (contracts/Flashloan.sol:53)
at async HardhatNode._mineBlockWithPendingTxs (node_modules\hardhat\src\internal\hardhat-network\provider\node.ts:1866:23)
at async HardhatNode.mineBlock (node_modules\hardhat\src\internal\hardhat-network\provider\node.ts:524:16)
at async EthModule._sendTransactionAndReturnHash (node_modules\hardhat\src\internal\hardhat-network\provider\modules\eth.ts:1482:18)
at async HardhatNetworkProvider.request (node_modules\hardhat\src\internal\hardhat-network\provider\provider.ts:124:18)
at async HardhatEthersSigner.sendTransaction (node_modules\@nomicfoundation\hardhat-ethers\src\signers.ts:125:18)
at async send (node_modules\ethers\src.ts\contract\contract.ts:313:20)
at async Proxy.executeFlashLoan (node_modules\ethers\src.ts\contract\contract.ts:352:16)
我检查了 receiveFlashLoan 和 Execute flashloan 函数中的所有检查。并多次阅读平衡器文档。另外，我检查了以下具有 flashLoan 函数定义的网址：https://github.com/balancer/balancer-v2-monorepo/blob/master/pkg/vault/contracts/FlashLoans.sol但是我无法修复该错误在我的代码中。 Mycode多次调用flashloan函数，但我不知道是什么原因造成的。我想确定这个错误的原因并找到解决方法。
我尝试使用uniswap和pancakeswap，将approve更改为safeApprove等。在非shell中，我尝试了所有相关和不相关的方法来改进我的代码并解决错误，但我保存的是，该错误与缺乏任何这些改进无关。当我发现以下github问题https://github.com/balancer/balancer-v2-monorepo/issues/2346时我了解到它并回答了我的问题。由于调用vault.swap函数而发生重入错误。但是我不能简单地使用uniswap，pancakeswap等来代替它，或者也不能使用平衡器的另一个交换功能。因此有两种方法可以解决问题。第一种方法是从平衡器v2获取闪贷并使用平衡器v1执行交换，第二种方法是正在使用另一种协议进行闪贷。在我的研究结束时，我了解到最好的选择是使用另一种协议来获取闪贷并执行掉期。