闪电贷套利

套利准备

本次使用流程

第一步我们要借款，根据dydx规则，我们需要先完成一个 initiateFlashLoan 函数（闪电贷开始函数）, 其amount即为需要借的数量

function initiateFlashLoan(uint256 _amount)
        external// 初始化闪电贷 必备
    {
        ISoloMargin solo = ISoloMargin(dydxAddress);//dydx地址0x1E0447b19BB6EcFdAe1e4AE1694b0C3659614e4e
        uint256 marketId = _getMarketIdFromTokenAddress(dydxAddress, WETHAddress);//获取市场ID、有多个借款token类型，需要去查询地址，参见0x1E0447b19BB6EcFdAe1e4AE1694b0C3659614e4e#readContract
        uint256 repayAmount = _getRepaymentAmountInternal(_amount);//计算返回资金，手续费+2wei
        IERC20(WETHAddress).approve(dydxAddress, repayAmount);//审批dydx对自己在weth资金的取回

        Actions.ActionArgs[] memory operations = new Actions.ActionArgs[](3);//初始化operations 三个槽，这里可以指定字节让dydx去发起闪电贷操作
        operations[0] = _getWithdrawAction(marketId, _amount);//槽0调_getWithdrawAction   放置市场ID和 借款量 合成回撤的Actions.ActionArgs动作数组--这里是回撤到本合约地址、也就是借款步骤
        operations[1] = _getCallAction(
            abi.encode(MyCustomData({token: WETHAddress, repayAmount: repayAmount}))//槽1调_getCallAction   放置MyCustomData结构体（token为weth地址、+2wei偿还量）  获取abi动作
        );
        operations[2] = _getDepositAction(marketId, repayAmount);//槽2调_getDepositAction   放置市场号和偿还量+2wei 偿还动作

        Account.Info[] memory accountInfos = new Account.Info[](1);//初始化accountinfo
        accountInfos[0] = _getAccountInfo();//accountinfo赋值 owner: address(this), number: 1

        solo.operate(accountInfos, operations);// 调solc.operate处理accountInfos、operations数组  accountInfos将指导该闪电贷提供者向谁交易 ，operations将指导有哪些动作需要执行(actionType需要在条件内)
    }

具体动作结构体为：

Actions.ActionArgs({
                actionType: Actions.ActionType.***,
                accountId: 0,
                amount: Types.AssetAmount({
                    sign: ***,(true/false)
                    denomination: Types.AssetDenomination.Wei,
                    ref: Types.AssetReference.Delta,
                    value: ***(amount/0)
                }),
                primaryMarketId: marketId,
                secondaryMarketId: 0,
                otherAddress: address(this),
                otherAccountId: 0,
                data: ***(abi字节)
            })

本合约就算借款了，在operate发出的交易中，dydx将回调我们合约的callFunction函数

dydx地址0x1E0447b19BB6EcFdAe1e4AE1694b0C3659614e4e，可见operate结构

function operate(
        Storage.State storage state,
        Account.Info[] memory accounts,//accountInfos
        Actions.ActionArgs[] memory actions//operations
    )
        public
    {
        Events.logOperation();

        _verifyInputs(accounts, actions);//验证传递数据

        (
            bool[] memory primaryAccounts,
            Cache.MarketCache memory cache
        ) = _runPreprocessing(
            state,
            accounts,
            actions
        );

        _runActions(
            state,
            accounts,
            actions,
            cache
        );//发送动作

        _verifyFinalState(
            state,
            accounts,
            primaryAccounts,
            cache
        );
    }

当_runActions发出指导动作，本次闪电贷即正式开始。

在运行到_getCallAction动作，构造的Action结构体指示 actionType: Actions.ActionType.Call ,此时_runActions将进入

	else  {
               assert(actionType == Actions.ActionType.Call);
               _call(state, Actions.parseCallArgs(accounts, action));
           }//具体参见0x1E0447b19BB6EcFdAe1e4AE1694b0C3659614e4e#code  _runActions函数
	...
       ...
       并回调ICallee(args.callee) 的 callFunction函数
function _call(
       Storage.State storage state,
       Actions.CallArgs memory args
   )
       private
   {
       state.requireIsOperator(args.account, msg.sender);

       ICallee(args.callee).callFunction(
           msg.sender,
           args.account,
           args.data
       );

       Events.logCall(args);
   }

callFunction操作-还款实现

操作第一步是将dydx给我们的WETH在池中回撤换回ETH，因为我们想要的是ETH

WETHAddress == 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2

WETH兑换成ETH–(weth合约)

WETH9(WETHAddress).withdraw(tokenBalanceBefore);//调weth取出ETH，数额为借来的weth量

function withdraw(uint wad) public {
        require(balanceOf[msg.sender] >= wad);
        balanceOf[msg.sender] -= wad;
        msg.sender.transfer(wad);
        Withdrawal(msg.sender, wad);
    }

套利操作

我们有了tokenBalanceBefore个ETH，接下来撰写套利逻辑

ETH换USDT–(Cofix交易所)

uint256 loopTimes = address(this).balance.div(cofixETHSapn);
    for(uint256 i = 0; i < loopTimes; i++) {
        CoFiXRouter(cofixRouter).swapExactETHForTokens{value:cofixETHSapn}(USDTAddress,cofixETHSapn.sub(nestPrice),1,address(this), address(this), uint256(block.timestamp).add(100));
    }

USDT 在Uniswap中兑换成ETH–(uniswap交易所)

uint256 usdtBalance = IERC20(USDTAddress).balanceOf(address(this));
   address[] memory uniData = new address[](2);
   uniData[0] = address(0xdAC17F958D2ee523a2206206994597C13D831ec7);
   uniData[1] = address(0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2);		UniswapV2Router(uniRouter).swapExactTokensForETH(usdtBalance,1,uniData,address(this),uint256(block.timestamp).add(100));

套利逻辑至此结束，由于当然此步不仅可以利用差价，还可能利用一些预言机漏洞认为创造差价等价格模型漏洞进行闪电贷套利操作。

还款操作

ETH兑换成WETH–(weth合约)

WETH9(WETHAddress).deposit{value:tokenBalanceBefore.add(2)};

一种未成功的实例。

同一时间在cofi一个ETH换来 71.187个UMA

于此同时

在第五步骤换回一个ETH需要 71.679 个UMA ,这时该交易就是不划算的，将无法进行套利

而如果在cofi 1个eth换出的uma大于在其他交易所 换回1个eth消耗的uma 我们就可以赚到他们之间的差价的uma。而此间当然存在滑点和手续费

部署

完整合约项目在：https://github.com/MLY0813/FlashSwapForCofixAndUni

pragma solidity 0.7.4;
pragma experimental ABIEncoderV2;

contract DydxFlashloanBase {// 基础dydx合约 需要继承
    using SafeMath for uint256;

    // -- Internal Helper functions -- //

    function _getMarketIdFromTokenAddress(address _solo, address token)
        internal
        view
        returns (uint256)
    {
        ISoloMargin solo = ISoloMargin(_solo);

        uint256 numMarkets = solo.getNumMarkets();

        address curToken;
        for (uint256 i = 0; i < numMarkets; i++) {
            curToken = solo.getMarketTokenAddress(i);

            if (curToken == token) {
                return i;
            }
        }

        revert("No marketId found for provided token");
    }

    function _getRepaymentAmountInternal(uint256 amount)
        internal
        pure
        returns (uint256)
    {
        // Needs to be overcollateralize
        // Needs to provide +2 wei to be safe
        return amount.add(2);
    }

    function _getAccountInfo() internal view returns (Account.Info memory) {
        return Account.Info({owner: address(this), number: 1});
    }

    function _getWithdrawAction(uint marketId, uint256 amount)
        internal
        view
        returns (Actions.ActionArgs memory)
    {
        return
            Actions.ActionArgs({
                actionType: Actions.ActionType.Withdraw,
                accountId: 0,
                amount: Types.AssetAmount({
                    sign: false,
                    denomination: Types.AssetDenomination.Wei,
                    ref: Types.AssetReference.Delta,
                    value: amount
                }),
                primaryMarketId: marketId,
                secondaryMarketId: 0,
                otherAddress: address(this),
                otherAccountId: 0,
                data: ""
            });
    }

    function _getCallAction(bytes memory data)
        internal
        view
        returns (Actions.ActionArgs memory)
    {
        return
            Actions.ActionArgs({
                actionType: Actions.ActionType.Call,
                accountId: 0,
                amount: Types.AssetAmount({
                    sign: false,
                    denomination: Types.AssetDenomination.Wei,
                    ref: Types.AssetReference.Delta,
                    value: 0
                }),
                primaryMarketId: 0,
                secondaryMarketId: 0,
                otherAddress: address(this),
                otherAccountId: 0,
                data: data
            });
    }

    function _getDepositAction(uint marketId, uint256 amount)
        internal
        view
        returns (Actions.ActionArgs memory)
    {
        return
            Actions.ActionArgs({
                actionType: Actions.ActionType.Deposit,
                accountId: 0,
                amount: Types.AssetAmount({
                    sign: true,
                    denomination: Types.AssetDenomination.Wei,
                    ref: Types.AssetReference.Delta,
                    value: amount
                }),
                primaryMarketId: marketId,
                secondaryMarketId: 0,
                otherAddress: address(this),
                otherAccountId: 0,
                data: ""
            });
    }
}

contract Love_Swap_V2 is DydxFlashloanBase {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;
    using address_make_payable for address;
    
    struct MyCustomData {
        address token;
        uint256 repayAmount;
    }
    
    address superMan;
    address cofixRouter = 0x26aaD4D82f6c9FA6E34D8c1067429C986A055872;
    address uniRouter = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D;
    address USDTAddress = 0xdAC17F958D2ee523a2206206994597C13D831ec7;
    address cofiAddress = 0x1a23a6BfBAdB59fa563008c0fB7cf96dfCF34Ea1;
    address WETHAddress = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
    address dydxAddress = 0x1E0447b19BB6EcFdAe1e4AE1694b0C3659614e4e;
    uint256 cofixETHSapn = 300 ether;
    uint256 nestPrice = 0.01 ether;
    
    
    constructor () public {
        superMan = address(tx.origin);
        IERC20(USDTAddress).safeApprove(cofixRouter, 10000000000000000);
        IERC20(USDTAddress).safeApprove(uniRouter, 10000000000000000);
    }
    
    function getCofixRouter() public view returns(address) {
        return cofixRouter;
    }
    
    function getUniRouter() public view returns(address) {
        return uniRouter;
    }
    
    function getNestPrice() public view returns(uint256) {
        return nestPrice;
    }
    
    function getSuperMan() public view returns(address) {
        return superMan;
    }
    
    function getCofixETHSapn() public view returns(uint256) {
        return cofixETHSapn;
    }
    
    function setCofixRouter(address _cofixRouter) public onlyOwner {
        cofixRouter = _cofixRouter;
    }
    
    function setUniRouter(address _uniRouter) public onlyOwner {
        uniRouter = _uniRouter;
    }
    
    function setNestPrice(uint256 _amount) public onlyOwner {
        nestPrice = _amount;
    }
    
    function setSuperMan(address _newMan) public onlyOwner {
        superMan = _newMan;
    }
    
    function setCofixETHSapn(uint256 _amount) public onlyOwner {
        cofixETHSapn = _amount;
    }
    
    //  实现操作
    function callFunction(
        address sender,
        Account.Info memory account,
        bytes memory data
    ) public {
        MyCustomData memory mcd = abi.decode(data, (MyCustomData));
        uint256 tokenBalanceBefore = IERC20(mcd.token).balanceOf(address(this));
        // money
        // WETH->ETH
        WETH9(WETHAddress).withdraw(tokenBalanceBefore);
        // ETH->USDT
        uint256 loopTimes = address(this).balance.div(cofixETHSapn);
        for(uint256 i = 0; i < loopTimes; i++) {
            CoFiXRouter(cofixRouter).swapExactETHForTokens{value:cofixETHSapn}(USDTAddress,cofixETHSapn.sub(nestPrice),1,address(this), address(this), uint256(block.timestamp).add(100));
        }
        // USDT->ETH
        uint256 usdtBalance = IERC20(USDTAddress).balanceOf(address(this));
        address[] memory uniData = new address[](2);
        uniData[0] = address(0xdAC17F958D2ee523a2206206994597C13D831ec7);
        uniData[1] = address(0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2);
        UniswapV2Router(uniRouter).swapExactTokensForETH(usdtBalance,1,uniData,address(this),uint256(block.timestamp).add(100));
        // ETH->WETH
        WETH9(WETHAddress).deposit{value:tokenBalanceBefore.add(2)};
        
        uint256 balOfLoanedToken = IERC20(mcd.token).balanceOf(address(this));
        require(
            balOfLoanedToken >= mcd.repayAmount,
            "Not enough funds to repay dydx loan!"
        );
        
    }
    
    function initiateFlashLoan(uint256 _amount)
        external
    {
        ISoloMargin solo = ISoloMargin(dydxAddress);
        uint256 marketId = _getMarketIdFromTokenAddress(dydxAddress, WETHAddress);
        uint256 repayAmount = _getRepaymentAmountInternal(_amount);
        IERC20(WETHAddress).approve(dydxAddress, repayAmount);

        Actions.ActionArgs[] memory operations = new Actions.ActionArgs[](3);
        operations[0] = _getWithdrawAction(marketId, _amount);
        operations[1] = _getCallAction(
            abi.encode(MyCustomData({token: WETHAddress, repayAmount: repayAmount}))
        );
        operations[2] = _getDepositAction(marketId, repayAmount);

        Account.Info[] memory accountInfos = new Account.Info[](1);
        accountInfos[0] = _getAccountInfo();

        solo.operate(accountInfos, operations);
    }
    

    function moreETH() public payable {
        
    }
    
    function turnOutToken(address token, uint256 amount) public onlyOwner{
        IERC20(token).safeTransfer(superMan, amount);
    }
    
    function turnOutETH(uint256 amount) public onlyOwner {
        address payable addr = superMan.make_payable();
        addr.transfer(amount);
    }
    
    function getTokenBalance(address token) public view returns(uint256) {
        return IERC20(token).balanceOf(address(this));
    }
    
    function getETHBalance() public view returns(uint256) {
        return address(this).balance;
    }
    
    modifier onlyOwner(){
        require(address(msg.sender) == superMan, "No authority");
        _;
    }
    
    receive() external payable {
        
    }
}

interface WETH9 {
    function deposit() external payable;
    function withdraw(uint wad) external;
}

interface CoFiXRouter {
    function swapExactETHForTokens(
        address token,
        uint amountIn,
        uint amountOutMin,
        address to,
        address rewardTo,
        uint deadline
    ) external payable returns (uint _amountIn, uint _amountOut);
    function swapExactTokensForTokens(
        address tokenIn,
        address tokenOut,
        uint amountIn,
        uint amountOutMin,
        address to,
        address rewardTo,
        uint deadline
    ) external payable returns (uint _amountIn, uint _amountOut);
    function swapExactTokensForETH(
        address token,
        uint amountIn,
        uint amountOutMin,
        address to,
        address rewardTo,
        uint deadline
    ) external payable returns (uint _amountIn, uint _amountOut);
}

interface UniswapV2Router {
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
     function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
}


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;
        }
        uint256 c = a * b;
        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;
    }
}

library Address {
    function isContract(address account) internal view returns (bool) {
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");
        (bool success, ) = recipient.call{value:amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
}

library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }
    function callOptionalReturn(IERC20 token, bytes memory data) private {
        require(address(token).isContract(), "SafeERC20: call to non-contract");
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

library address_make_payable {
   function make_payable(address x) internal pure returns (address payable) {
      return address(uint160(x));
   }
}

interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// dydx


library Account {
    enum Status {Normal, Liquid, Vapor}
    struct Info {
        address owner; // The address that owns the account
        uint256 number; // A nonce that allows a single address to control many accounts
    }
    struct Storage {
        mapping(uint256 => Types.Par) balances; // Mapping from marketId to principal
        Status status;
    }
}


library Actions {
    enum ActionType {
        Deposit, // supply tokens
        Withdraw, // borrow tokens
        Transfer, // transfer balance between accounts
        Buy, // buy an amount of some token (publicly)
        Sell, // sell an amount of some token (publicly)
        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 AccountLayout {OnePrimary, TwoPrimary, PrimaryAndSecondary}

    enum MarketLayout {ZeroMarkets, OneMarket, TwoMarkets}

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

    struct DepositArgs {
        Types.AssetAmount amount;
        Account.Info account;
        uint256 market;
        address from;
    }

    struct WithdrawArgs {
        Types.AssetAmount amount;
        Account.Info account;
        uint256 market;
        address to;
    }

    struct TransferArgs {
        Types.AssetAmount amount;
        Account.Info accountOne;
        Account.Info accountTwo;
        uint256 market;
    }

    struct BuyArgs {
        Types.AssetAmount amount;
        Account.Info account;
        uint256 makerMarket;
        uint256 takerMarket;
        address exchangeWrapper;
        bytes orderData;
    }

    struct SellArgs {
        Types.AssetAmount amount;
        Account.Info account;
        uint256 takerMarket;
        uint256 makerMarket;
        address exchangeWrapper;
        bytes orderData;
    }

    struct TradeArgs {
        Types.AssetAmount amount;
        Account.Info takerAccount;
        Account.Info makerAccount;
        uint256 inputMarket;
        uint256 outputMarket;
        address autoTrader;
        bytes tradeData;
    }

    struct LiquidateArgs {
        Types.AssetAmount amount;
        Account.Info solidAccount;
        Account.Info liquidAccount;
        uint256 owedMarket;
        uint256 heldMarket;
    }

    struct VaporizeArgs {
        Types.AssetAmount amount;
        Account.Info solidAccount;
        Account.Info vaporAccount;
        uint256 owedMarket;
        uint256 heldMarket;
    }

    struct CallArgs {
        Account.Info account;
        address callee;
        bytes data;
    }
}


library Decimal {
    struct D256 {
        uint256 value;
    }
}


library Interest {
    struct Rate {
        uint256 value;
    }

    struct Index {
        uint96 borrow;
        uint96 supply;
        uint32 lastUpdate;
    }
}


library Monetary {
    struct Price {
        uint256 value;
    }
    struct Value {
        uint256 value;
    }
}


library Storage {
    // All information necessary for tracking a market
    struct Market {
        // Contract address of the associated ERC20 token
        address token;
        // Total aggregated supply and borrow amount of the entire market
        Types.TotalPar totalPar;
        // Interest index of the market
        Interest.Index index;
        // Contract address of the price oracle for this market
        address priceOracle;
        // Contract address of the interest setter for this market
        address interestSetter;
        // Multiplier on the marginRatio for this market
        Decimal.D256 marginPremium;
        // Multiplier on the liquidationSpread for this market
        Decimal.D256 spreadPremium;
        // Whether additional borrows are allowed for this market
        bool isClosing;
    }

    // The global risk parameters that govern the health and security of the system
    struct RiskParams {
        // Required ratio of over-collateralization
        Decimal.D256 marginRatio;
        // Percentage penalty incurred by liquidated accounts
        Decimal.D256 liquidationSpread;
        // Percentage of the borrower's interest fee that gets passed to the suppliers
        Decimal.D256 earningsRate;
        // The minimum absolute borrow value of an account
        // There must be sufficient incentivize to liquidate undercollateralized accounts
        Monetary.Value minBorrowedValue;
    }

    // The maximum RiskParam values that can be set
    struct RiskLimits {
        uint64 marginRatioMax;
        uint64 liquidationSpreadMax;
        uint64 earningsRateMax;
        uint64 marginPremiumMax;
        uint64 spreadPremiumMax;
        uint128 minBorrowedValueMax;
    }

    // The entire storage state of Solo
    struct State {
        // number of markets
        uint256 numMarkets;
        // marketId => Market
        mapping(uint256 => Market) markets;
        // owner => account number => Account
        mapping(address => mapping(uint256 => Account.Storage)) accounts;
        // Addresses that can control other users accounts
        mapping(address => mapping(address => bool)) operators;
        // Addresses that can control all users accounts
        mapping(address => bool) globalOperators;
        // mutable risk parameters of the system
        RiskParams riskParams;
        // immutable risk limits of the system
        RiskLimits riskLimits;
    }
}


library Types {
    enum AssetDenomination {
        Wei, // the amount is denominated in wei
        Par // the amount is denominated in par
    }

    enum AssetReference {
        Delta, // the amount is given as a delta from the current value
        Target // the amount is given as an exact number to end up at
    }

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

    struct TotalPar {
        uint128 borrow;
        uint128 supply;
    }

    struct Par {
        bool sign; // true if positive
        uint128 value;
    }

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


abstract contract ISoloMargin{
    struct OperatorArg {
        address operator;
        bool trusted;
    }

    function ownerSetSpreadPremium(
        uint256 marketId,
        Decimal.D256 memory spreadPremium
    ) public virtual;

    function getIsGlobalOperator(address operator) public virtual returns (bool);

    function getMarketTokenAddress(uint256 marketId)
        public
        virtual
        view
        returns (address);

    function ownerSetInterestSetter(uint256 marketId, address interestSetter)
        public virtual;

    function getAccountValues(Account.Info memory account)
        public
        virtual
        returns (Monetary.Value memory, Monetary.Value memory);

    function getMarketPriceOracle(uint256 marketId)
        public
        virtual
        returns (address);

    function getMarketInterestSetter(uint256 marketId)
        public
        virtual
        returns (address);

    function getMarketSpreadPremium(uint256 marketId)
        public
        virtual
        returns (Decimal.D256 memory);

    function getNumMarkets() public view virtual returns (uint256);

    function ownerWithdrawUnsupportedTokens(address token, address recipient)
        public
        virtual
        returns (uint256);

    function ownerSetMinBorrowedValue(Monetary.Value memory minBorrowedValue)
        public
        virtual;

    function ownerSetLiquidationSpread(Decimal.D256 memory spread) public virtual;

    function ownerSetEarningsRate(Decimal.D256 memory earningsRate) public virtual;

    function getIsLocalOperator(address owner, address operator)
        public
        virtual
        returns (bool);

    function getAccountPar(Account.Info memory account, uint256 marketId)
        public
        virtual
        returns (Types.Par memory);

    function ownerSetMarginPremium(
        uint256 marketId,
        Decimal.D256 memory marginPremium
    ) public
    virtual;

    function getMarginRatio() public virtual returns (Decimal.D256 memory);

    function getMarketCurrentIndex(uint256 marketId)
        public
        virtual
        returns (Interest.Index memory);

    function getMarketIsClosing(uint256 marketId) public virtual returns (bool);

    function getRiskParams() public virtual returns (Storage.RiskParams memory);

    function getAccountBalances(Account.Info memory account)
        public
        virtual
        returns (address[] memory, Types.Par[] memory, Types.Wei[] memory);

    function renounceOwnership() public virtual;

    function getMinBorrowedValue() public virtual returns (Monetary.Value memory);

    function setOperators(OperatorArg[] memory args) public virtual;

    function getMarketPrice(uint256 marketId) public virtual returns (address);

    function owner() public virtual returns (address);

    function isOwner() public virtual returns (bool);

    function ownerWithdrawExcessTokens(uint256 marketId, address recipient)
        public
        virtual
        returns (uint256);

    function ownerAddMarket(
        address token,
        address priceOracle,
        address interestSetter,
        Decimal.D256 memory marginPremium,
        Decimal.D256 memory spreadPremium
    ) public
    virtual;

    function operate(
        Account.Info[] memory accounts,
        Actions.ActionArgs[] memory actions
    ) public
    virtual;

    function getMarketWithInfo(uint256 marketId)
        public
        virtual
        returns (
            Storage.Market memory,
            Interest.Index memory,
            Monetary.Price memory,
            Interest.Rate memory
        );

    function ownerSetMarginRatio(Decimal.D256 memory ratio) public virtual;

    function getLiquidationSpread() public virtual returns (Decimal.D256 memory);

    function getAccountWei(Account.Info memory account, uint256 marketId)
        public
        virtual
        returns (Types.Wei memory);

    function getMarketTotalPar(uint256 marketId)
        public
        virtual
        returns (Types.TotalPar memory);

    function getLiquidationSpreadForPair(
        uint256 heldMarketId,
        uint256 owedMarketId
    ) public virtual returns (Decimal.D256 memory);

    function getNumExcessTokens(uint256 marketId)
        public
        virtual
        returns (Types.Wei memory);

    function getMarketCachedIndex(uint256 marketId)
        public
        virtual
        returns (Interest.Index memory);

    function getAccountStatus(Account.Info memory account)
        public
        virtual
        returns (uint8);

    function getEarningsRate() public virtual returns (Decimal.D256 memory);

    function ownerSetPriceOracle(uint256 marketId, address priceOracle) public virtual;

    function getRiskLimits() public virtual returns (Storage.RiskLimits memory);

    function getMarket(uint256 marketId)
        public
        virtual
        returns (Storage.Market memory);

    function ownerSetIsClosing(uint256 marketId, bool isClosing) public virtual;

    function ownerSetGlobalOperator(address operator, bool approved) public virtual;

    function transferOwnership(address newOwner) public virtual;

    function getAdjustedAccountValues(Account.Info memory account)
        public
        virtual
        returns (Monetary.Value memory, Monetary.Value memory);

    function getMarketMarginPremium(uint256 marketId)
        public
        virtual
        returns (Decimal.D256 memory);

    function getMarketInterestRate(uint256 marketId)
        public
        virtual
        returns (Interest.Rate memory);
}

测试网这样的汇率便是可以的：

一个ETH换出1289个USDT

然后1289个USDT全部换出19.7个weth:

这样归还后就能净赚18.7个wETH + 0.66594938个USDT - 2weiETH(手续费)

remix部署，传递1000000000000000000, 也就是1ether, uint256默认和wei单位相同：

但是测试网未很好的部署dydx则无法进行完整贷款操作0xdbf0497b是initiateFlashLoan(uint)的abi编码，由于目标地址不是一个合约地址，因此未能成功调用

调用的是initiateFlashLoan(uint256)

其值为1*10^18 ,也就是1ether