FlashArbExecutor

{{
  "language": "Solidity",
  "sources": {
    "@openzeppelin/contracts/access/Ownable.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)

pragma solidity ^0.8.20;

import {Context} from "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * The initial owner is set to the address provided by the deployer. This can
 * later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    /**
     * @dev The caller account is not authorized to perform an operation.
     */
    error OwnableUnauthorizedAccount(address account);

    /**
     * @dev The owner is not a valid owner account. (eg. `address(0)`)
     */
    error OwnableInvalidOwner(address owner);

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
     */
    constructor(address initialOwner) {
        if (initialOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(initialOwner);
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        if (owner() != _msgSender()) {
            revert OwnableUnauthorizedAccount(_msgSender());
        }
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        if (newOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}
"
    },
    "@openzeppelin/contracts/token/ERC20/IERC20.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.4.0) (token/ERC20/IERC20.sol)

pragma solidity >=0.4.16;

/**
 * @dev Interface of the ERC-20 standard as defined in the ERC.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the value of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 value) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the
     * allowance mechanism. `value` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 value) external returns (bool);
}
"
    },
    "@openzeppelin/contracts/utils/Context.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.1) (utils/Context.sol)

pragma solidity ^0.8.20;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}
"
    },
    "@openzeppelin/contracts/utils/ReentrancyGuard.sol": {
      "content": "// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (utils/ReentrancyGuard.sol)

pragma solidity ^0.8.20;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If EIP-1153 (transient storage) is available on the chain you're deploying at,
 * consider using {ReentrancyGuardTransient} instead.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant NOT_ENTERED = 1;
    uint256 private constant ENTERED = 2;

    uint256 private _status;

    /**
     * @dev Unauthorized reentrant call.
     */
    error ReentrancyGuardReentrantCall();

    constructor() {
        _status = NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be NOT_ENTERED
        if (_status == ENTERED) {
            revert ReentrancyGuardReentrantCall();
        }

        // Any calls to nonReentrant after this point will fail
        _status = ENTERED;
    }

    function _nonReentrantAfter() private {
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = NOT_ENTERED;
    }

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == ENTERED;
    }
}
"
    },
    "contracts/FlashArbExecutor.sol": {
      "content": "// ==============================================================================
// File: FlashArbExecutor.sol
// Version: v0.3.10_NovaOps_Hardening
// Summary: Flash loan arbitrage executor with minimal hardening
// Change Log:
//   [2025-10-20] Initial header injection
//   [2025-10-22] v0.3.10 Hardening:
//                - Enforce final hop tokenOut == WETH
//                - Require adapters set before swap
//                - Safe approvals (reset to 0, then set amount)
//                - nonReentrant on executeOperation
// Explanation:
//   Hardened version of v0.3.9 to prevent adapter misuse, slippage errors,
//   and unsafe approvals. Fully compatible with existing deployment scripts.
// Rollback:
//   Restore FlashArbExecutor.sol v0.3.9_NovaOps if needed.
// Run command: N/A (deployed via scripts/deploy.ts)
// ==============================================================================

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.25;

/* -------------------------------------------------------------------------- */
/*                               Import Statements                            */
/* -------------------------------------------------------------------------- */
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {ReentrancyGuard} from "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/* -------------------------------------------------------------------------- */
/*                                  Interfaces                                */
/* -------------------------------------------------------------------------- */
interface IAavePool {
    function flashLoanSimple(
        address receiver,
        address asset,
        uint256 amount,
        bytes calldata params,
        uint16 referralCode
    ) external;
}

interface IFlashLoanSimpleReceiver {
    function executeOperation(
        address asset,
        uint256 amount,
        uint256 premium,
        address initiator,
        bytes calldata params
    ) external returns (bool);
}

interface IUniV3Adapter {
    function swapExactTokensForTokens(
        address tokenIn,
        address tokenOut,
        uint256 amountIn,
        uint256 minOut
    ) external returns (uint256);
}

interface IBalancerAdapter {
    function swapExactTokensForTokens(
        address tokenIn,
        address tokenOut,
        uint256 amountIn,
        uint256 minOut
    ) external returns (uint256);
}

/* -------------------------------------------------------------------------- */
/*                             Flash Arbitrage Executor                       */
/* -------------------------------------------------------------------------- */

contract FlashArbExecutor is Ownable, ReentrancyGuard, IFlashLoanSimpleReceiver {
    /* ---------------------------------------------------------------------- */
    /*                                State Vars                              */
    /* ---------------------------------------------------------------------- */
    IAavePool public immutable aavePool;
    address public immutable WETH;
    address public uniAdapter;
    address public balAdapter;
    address public treasury;

    /* ---------------------------------------------------------------------- */
    /*                                 Structs & Enums                        */
    /* ---------------------------------------------------------------------- */
    enum Venue {
        UniV3,
        Balancer
    }

    struct Step {
        Venue venue;
        address tokenIn;
        address tokenOut;
        uint256 minOut;
    }

    /* ---------------------------------------------------------------------- */
    /*                                  Events                                */
    /* ---------------------------------------------------------------------- */
    event RouteExecuted(uint256 amountIn, uint256 amountOut, int256 profit);
    event AdapterUpdated(address uni, address bal);
    event TreasuryUpdated(address treasury);
    event ExecutionLog(string message, uint256 value);

    /* ---------------------------------------------------------------------- */
    /*                               Constructor                              */
    /* ---------------------------------------------------------------------- */
    constructor(address _aavePool, address _weth, address _treasury)
        Ownable(msg.sender)
    {
        aavePool = IAavePool(_aavePool);
        WETH = _weth;
        treasury = _treasury;

        emit ExecutionLog("FlashArbExecutor deployed", block.timestamp);
        emit ExecutionLog("Owner set", uint256(uint160(msg.sender)));
    }

    /* ---------------------------------------------------------------------- */
    /*                             Admin Functions                            */
    /* ---------------------------------------------------------------------- */
    function setAdapters(address _uni, address _bal) external onlyOwner {
        uniAdapter = _uni;
        balAdapter = _bal;
        emit AdapterUpdated(_uni, _bal);
        emit ExecutionLog("Adapters updated", block.timestamp);
    }

    function setTreasury(address t) external onlyOwner {
        treasury = t;
        emit TreasuryUpdated(t);
        emit ExecutionLog("Treasury updated", block.timestamp);
    }

    /* ---------------------------------------------------------------------- */
    /*                         Capital-based Execution                        */
    /* ---------------------------------------------------------------------- */
    function executeWithCapital(
        uint256 amountIn,
        Step[] calldata steps,
        uint256 minFinalOut
    ) external nonReentrant onlyOwner {
        emit ExecutionLog("Executing with capital", amountIn);
        IERC20(WETH).transferFrom(msg.sender, address(this), amountIn);
        _executeSteps(amountIn, steps, minFinalOut);
    }

    /* ---------------------------------------------------------------------- */
    /*                            Flash Loan Execution                        */
    /* ---------------------------------------------------------------------- */
    function flashArb(
        uint256 amount,
        Step[] calldata steps,
        uint256 minFinalOut
    ) external onlyOwner {
        emit ExecutionLog("Initiating flash loan", amount);
        bytes memory params = abi.encode(steps, minFinalOut);
        aavePool.flashLoanSimple(address(this), WETH, amount, params, 0);
    }

    function executeOperation(
        address asset,
        uint256 amount,
        uint256 premium,
        address initiator,
        bytes calldata params
    ) external override nonReentrant returns (bool) {
        require(msg.sender == address(aavePool), "BadCaller");
        require(initiator == address(this), "BadInitiator");
        require(asset == WETH, "AssetNotWETH");

        emit ExecutionLog("Flash loan received", amount);

        (Step[] memory steps, uint256 minFinalOut) = abi.decode(params, (Step[], uint256));
        uint256 finalOut = _executeSteps(amount, steps, minFinalOut);

        uint256 repay = amount + premium;
        require(finalOut >= repay, "NoProfit");

        IERC20(WETH).approve(address(aavePool), repay);

        uint256 profit = finalOut - repay;
        emit ExecutionLog("Profit calculated", profit);

        if (profit > 0 && treasury != address(0)) {
            IERC20(WETH).transfer(treasury, profit);
            emit ExecutionLog("Profit sent to treasury", profit);
        }

        return true;
    }

    /* ---------------------------------------------------------------------- */
    /*                            Internal Execution                          */
    /* ---------------------------------------------------------------------- */
    function _executeSteps(
        uint256 amountIn,
        Step[] memory steps,
        uint256 minFinalOut
    ) internal returns (uint256 amount) {
        amount = amountIn;
        emit ExecutionLog("Executing swap route", steps.length);

        // Require adapters configured
        require(uniAdapter != address(0) && balAdapter != address(0), "AdaptersNotSet");

        // Enforce route ends in WETH
        if (steps.length > 0) {
            require(steps[steps.length - 1].tokenOut == WETH, "FinalNotWETH");
        }

        for (uint256 i = 0; i < steps.length; i++) {
            Step memory s = steps[i];
            address adapter = (s.venue == Venue.UniV3) ? uniAdapter : balAdapter;
            require(adapter != address(0), "AdapterNotSet");

            // Safe approval pattern: reset, then approve
            IERC20 tokenIn = IERC20(s.tokenIn);
            if (tokenIn.allowance(address(this), adapter) > 0) {
                tokenIn.approve(adapter, 0);
            }
            tokenIn.approve(adapter, amount);

            // Perform swap
            amount =
                s.venue == Venue.UniV3
                    ? IUniV3Adapter(adapter).swapExactTokensForTokens(s.tokenIn, s.tokenOut, amount, s.minOut)
                    : IBalancerAdapter(adapter).swapExactTokensForTokens(s.tokenIn, s.tokenOut, amount, s.minOut);

            emit ExecutionLog("Step executed", i);
        }

        require(amount >= minFinalOut, "Slippage");
        emit RouteExecuted(amountIn, amount, int256(amount) - int256(amountIn));
    }

    /* ---------------------------------------------------------------------- */
    /*                           Emergency Sweep                              */
    /* ---------------------------------------------------------------------- */
    function sweep(address token, address to, uint256 amt) external onlyOwner {
        IERC20(token).transfer(to, amt);
        emit ExecutionLog("Sweep executed", amt);
    }
}

/* -------------------------------------------------------------------------- */
/*                           Explanation of Key Changes                       */
/* -------------------------------------------------------------------------- */
// 1. Added adapter checks and final WETH enforcement.
// 2. Added safe approvals (reset then approve).
// 3. executeOperation now nonReentrant.
// 4. Fully backward compatible with v0.3.9.

/* -------------------------------------------------------------------------- */
/*                              Rollback Instructions                         */
/* -------------------------------------------------------------------------- */
// - To revert to v0.3.9, remove adapter checks and nonReentrant modifier.
// - Restore approvals to single-line style.
// --------------------------------------------------------------------------
"
    }
  },
  "settings": {
    "optimizer": {
      "enabled": true,
      "runs": 400
    },
    "evmVersion": "paris",
    "outputSelection": {
      "*": {
        "*": [
          "evm.bytecode",
          "evm.deployedBytecode",
          "devdoc",
          "userdoc",
          "metadata",
          "abi"
        ]
      }
    }
  }
}}