TransferHelper: TRANSFER_FROM_FAILED

Question

我想用一些eth (从一笔闪存贷款中得到的)交换一个令牌的x值。然后用令牌交换一些eth，偿还短期贷款，并保持利润。对于闪存贷款，我使用了dYdX，为了交换，我使用了Uniswap和Sushiswap。当我运行代码时，我会收到以下消息：Reason provided by the contract: "TransferHelper: TRANSFER_FROM_FAILED"。我想弄清楚错误是从哪里来的。下面是我要分离的代码，因为它是一个非常大的契约：

Flashloan

interface Structs {
    struct Val {
        uint256 value;
    }

    enum ActionType {
        Deposit, // supply tokens
        Withdraw, // borrow tokens
        Transfer, // transfer balance between accounts
        Buy, // buy an amount of some token (externally)
        Sell, // sell an amount of some token (externally)
        Trade, // trade tokens against another account
        Liquidate, // liquidate an undercollateralized or expiring account
        Vaporize, // use excess tokens to zero-out a completely negative account
        Call // send arbitrary data to an address
    }

    enum AssetDenomination {
        Wei // the amount is denominated in wei
    }

    enum AssetReference {
        Delta // the amount is given as a delta from the current value
    }

    struct AssetAmount {
        bool sign; // true if positive
        AssetDenomination denomination;
        AssetReference ref;
        uint256 value;
    }

    struct ActionArgs {
        ActionType actionType;
        uint256 accountId;
        AssetAmount amount;
        uint256 primaryMarketId;
        uint256 secondaryMarketId;
        address otherAddress;
        uint256 otherAccountId;
        bytes data;
    }

    struct Info {
        address owner; // The address that owns the account
        uint256 number; // A nonce that allows a single address to control many accounts
    }

    struct Wei {
        bool sign; // true if positive
        uint256 value;
    }
}

abstract contract DyDxPool is Structs {
    function getAccountWei(Info memory account, uint256 marketId)
        public
        view
        virtual
        returns (Wei memory);

    function operate(Info[] memory, ActionArgs[] memory) public virtual;
}

contract DyDxFlashLoan is Structs {
    DyDxPool pool = DyDxPool(0x1E0447b19BB6EcFdAe1e4AE1694b0C3659614e4e);

    address public WETH = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
    mapping(address => uint256) public currencies;

    constructor() {
        currencies[WETH] = 1;
    }

    modifier onlyPool() {
        require(
            msg.sender == address(pool),
            "FlashLoan: could be called by DyDx pool only"
        );
        _;
    }

    function tokenToMarketId(address token) public view returns (uint256) {
        uint256 marketId = currencies[token];
        require(marketId != 0, "FlashLoan: Unsupported token");
        return marketId - 1;
    }

    // the DyDx will call `callFunction(address sender, Info memory accountInfo, bytes memory data) public` after during `operate` call
    function flashloan(
        address token,
        uint256 amount,
        bytes memory data
    ) internal {
        IERC20(token).approve(address(pool), amount + 1);
        Info[] memory infos = new Info[](1);
        ActionArgs[] memory args = new ActionArgs[](3);

        infos[0] = Info(address(this), 0);

        AssetAmount memory wamt = AssetAmount(
            false,
            AssetDenomination.Wei,
            AssetReference.Delta,
            amount
        );
        ActionArgs memory withdraw;
        withdraw.actionType = ActionType.Withdraw;
        withdraw.accountId = 0;
        withdraw.amount = wamt;
        withdraw.primaryMarketId = tokenToMarketId(token);
        withdraw.otherAddress = address(this);

        args[0] = withdraw;

        ActionArgs memory call;
        call.actionType = ActionType.Call;
        call.accountId = 0;
        call.otherAddress = address(this);
        call.data = data;

        args[1] = call;

        ActionArgs memory deposit;
        AssetAmount memory damt = AssetAmount(
            true,
            AssetDenomination.Wei,
            AssetReference.Delta,
            amount + 1
        );
        deposit.actionType = ActionType.Deposit;
        deposit.accountId = 0;
        deposit.amount = damt;
        deposit.primaryMarketId = tokenToMarketId(token);
        deposit.otherAddress = address(this);

        args[2] = deposit;

        pool.operate(infos, args);
    }
}

执行代码：

contract Arbitrage is DyDxFlashLoan {
    IUniswapV2Router02 public immutable uRouter;
    IUniswapV2Router02 public immutable sRouter;

    address public owner;

    constructor(address _uRouter, address _sRouter) {
        uRouter = IUniswapV2Router02(_uRouter);
        sRouter = IUniswapV2Router02(_sRouter);
        owner = msg.sender;
    }

    function executeTrade(
        address _tokenA,
        address _tokenB,
        uint256 _flashAmount,
        bool _startOnUniswap
    ) external {
        uint balanceBefore = IERC20(_tokenA).balanceOf(address(this));
        bytes memory data = abi.encode(
            _startOnUniswap,
            _tokenA,
            _tokenB,
            _flashAmount,
            balanceBefore
        );
        flashloan(_tokenA, _flashAmount, data);
    }

    function callFunction(
        address,
        Info calldata,
        bytes calldata data
    ) external onlyPool {
        (
            bool _startOnUniswap,
            address _tokenA,
            address _tokenB,
            uint256 flashAmount,
            uint256 balanceBefore
        ) = abi.decode(data, (bool, address, address, uint256, uint256));

        uint balanceAfter = IERC20(_tokenA).balanceOf(address(this));

        require(
            balanceAfter - balanceBefore == flashAmount,
            "Didn't receive flash loan"
        );

        address[] memory tokens = new address[](2);

        tokens[0] = _tokenA;
        tokens[1] = _tokenB;

        if (_startOnUniswap) {
            swapOnUniswap(flashAmount, 0, tokens);

            tokens[0] = _tokenB;
            tokens[1] = _tokenA;

            swapOnSushiswap(
                IERC20(tokens[0]).balanceOf(address(this)),
                10,
                tokens
            );
        } else {
            swapOnSushiswap(flashAmount, 0, tokens);

            tokens[0] = _tokenB;
            tokens[1] = _tokenA;

            swapOnUniswap(
                IERC20(tokens[0]).balanceOf(address(this)),
                10,
                tokens
            );
        }
    }

    function swapOnUniswap(
        uint _amountIn,
        uint _amountOut,
        address[] memory _path
    ) internal {
        require(
            IERC20(_path[0]).approve(address(uRouter), _amountIn),
            "Uniswap failed the approval"
        );

        uint[] memory amounts = uRouter.swapExactTokensForTokens(
            _amountIn,
            _amountOut,
            _path,
            address(this),
            (block.timestamp + 1200)
        );
        require(
            amounts[1] == IERC20(_path[0]).balanceOf(address(this)),
            "Didn't receive tokens from swap"
        );
    }

    function swapOnSushiswap(
        uint _amountIn,
        uint _amountOut,
        address[] memory _path
    ) internal {
        require(
            IERC20(_path[0]).approve(address(sRouter), _amountIn),
            "Sushiswap failed the approval"
        );

        uint[] memory amounts = uRouter.swapExactTokensForTokens(
            _amountIn,
            _amountOut,
            _path,
            address(this),
            (block.timestamp + 1200)
        );

        require(
            amounts[1] == IERC20(_path[0]).balanceOf(address(this)),
            "Didn't receive tokens from swap"
        );
    } 
}

如果你有任何建议，请回答，这将是非常有帮助的。

Answer 1

所以这个错误是非常愚蠢的，我对任何花费时间试图找出问题所在的人表示歉意。问题是我使用uRouter在swapOnSushiswap函数中交换Sushiswap。

Answer 2

首先，您可以通过检查合同是否有足够的备抵来执行交换来验证令牌的备抵。您可以检查_path0令牌对于uRouter和sRouter的充分性，然后检查您正在使用的令牌契约是否有非标准实现，并且是正确的ERC20，然后检查当您调用uRouter()时，如果发出了相应的审批事件，还可以添加事件日志记录或双重检查令牌余额。