GuardedEthTokenSwapper

{{
  "language": "Solidity",
  "sources": {
    "src/GuardedEthTokenSwapper.sol": {
      "content": "// SPDX-License-Identifier: MIT
pragma solidity ^0.8.30;

import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {ReentrancyGuard} from "@openzeppelin/contracts/utils/ReentrancyGuard.sol";

// --- Chainlink Aggregator ---
interface AggregatorV3Interface {
    function latestRoundData() external view returns (uint80, int256, uint256, uint256, uint80);
    function decimals() external view returns (uint8);
}

// --- ERC20 / WETH / Uniswap v3 ---
interface IERC20 {
    function decimals() external view returns (uint8);
    function transfer(address, uint256) external returns (bool);
}

interface IWETH9 {
    function deposit() external payable;
    function approve(address, uint256) external returns (bool);
}

interface ISwapRouter {
    struct ExactInputSingleParams {
        address tokenIn;
        address tokenOut;
        uint24 fee;
        address recipient;
        uint256 deadline;
        uint256 amountIn;
        uint256 amountOutMinimum;
        uint160 sqrtPriceLimitX96;
    }

    function exactInputSingle(ExactInputSingleParams calldata) external payable returns (uint256 amountOut);
}

library SafeTransfer {
    function transfer(address token, address to, uint256 amount) internal returns (bool) {
        (bool ok, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, amount));
        return ok && (data.length == 0 || abi.decode(data, (bool)));
    }
}

/**
 * @title GuardedEthTokenSwapper
 *     @author ryley-o
 *     @notice Simplified ETH-only token swapper that uses TOKEN/ETH Chainlink price feeds.
 *     This version is optimized for ETH pairs only, removing USD complexity and reducing gas costs.
 *
 *     ⚠️ USE AT YOUR OWN RISK. DO NOT USE THIS CONTRACT IF YOU DO NOT UNDERSTAND THE RISKS.
 *     ⚠️ THIS CONTRACT HAS NOT BEEN PROFESSIONALLY AUDITED.
 *     ⚠️ ONLY USE FUNDS YOU CAN AFFORD TO LOSE.
 *
 *     @dev It guards against severe sandwich attacks by checking TOKEN/ETH prices from Chainlink oracles.
 *     The contract validates swap outcomes against oracle prices with configurable tolerance per token.
 *     All supported tokens must be configured by the owner before swapping is enabled.
 */
contract GuardedEthTokenSwapper is Ownable, ReentrancyGuard {
    using SafeTransfer for address;

    // Mainnet constants
    address public constant UNISWAP_V3_ROUTER = 0xE592427A0AEce92De3Edee1F18E0157C05861564;
    address public constant WETH9_ADDR = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;

    // Oracle staleness threshold (24 hours)
    uint256 public constant MAX_ORACLE_STALENESS = 24 hours;

    ISwapRouter public immutable router = ISwapRouter(UNISWAP_V3_ROUTER);
    IWETH9 public immutable weth = IWETH9(WETH9_ADDR);

    /**
     * Simplified per-token registry entry (fits in 1 storage slot):
     * - aggregator      : 20 bytes (TOKEN/ETH Chainlink feed)
     * - decimalsCache   : 1 byte  (aggregator.decimals())
     * - feeTier         : 3 bytes (Uniswap v3 fee: 500, 3000, 10000)
     * - toleranceBps    : 2 bytes (oracle ±accuracy in basis points, e.g. 200 = 2%)
     * Total: 26 bytes (fits in 1 slot with 6 bytes padding)
     */
    struct FeedInfo {
        address aggregator; // 20 bytes - TOKEN/ETH price feed
        uint8 decimalsCache; // 1 byte  - cached decimals from aggregator
        uint24 feeTier; // 3 bytes - Uniswap V3 fee tier
        uint16 toleranceBps; // 2 bytes - price tolerance in basis points
        // 6 bytes padding
    }

    mapping(address => FeedInfo) public feeds; // token => config

    // Errors / events
    error NoEthSent();
    error FeedNotSet();
    error FeeNotSet();
    error OracleBad();
    error OracleStale();
    error InvalidSlippage();
    error ApproveFailed();
    error TransferFailed();

    event FeedSet(
        address indexed token, address indexed aggregator, uint8 decimals, uint24 feeTier, uint16 toleranceBps
    );
    event FeedRemoved(address indexed token);
    event Swapped(
        address indexed user,
        address indexed token,
        uint256 ethIn,
        uint256 tokensOut,
        uint24 fee,
        uint256 minOut,
        uint256 tokenEthPrice
    );

    /**
     * @notice Initializes the contract and sets the deployer as owner
     * @dev No ETH/USD feed needed - we only use TOKEN/ETH feeds
     */
    constructor() Ownable(msg.sender) {
        // Deployer becomes the owner via Ownable constructor
    }

    // --- Admin: set/update entries (token, aggregator, feeTier, toleranceBps) ---
    /**
     * @notice Configures price feeds and swap parameters for multiple tokens (owner only)
     * @dev All arrays must be the same length. Each token gets a dedicated Chainlink feed and Uniswap config.
     * @param tokens Array of ERC20 token addresses to configure
     * @param aggregators Array of Chainlink TOKEN/ETH price feed addresses
     * @param feeTiers Array of Uniswap V3 fee tiers (500=0.05%, 3000=0.30%, 10000=1.00%)
     * @param toleranceBpsArr Array of price tolerance values in basis points (e.g., 200=2%)
     * Requirements:
     * - All arrays must have matching length
     * - Token and aggregator addresses must be non-zero
     * - Fee tiers must be 500, 3000, or 10000
     * - Tolerance must be ≤ 2000 bps (20%)
     */
    function setFeeds(
        address[] calldata tokens,
        address[] calldata aggregators,
        uint24[] calldata feeTiers,
        uint16[] calldata toleranceBpsArr
    ) external onlyOwner {
        uint256 n = tokens.length;
        require(n == aggregators.length && n == feeTiers.length && n == toleranceBpsArr.length, "len mismatch");
        for (uint256 i; i < n; ++i) {
            _setFeed(tokens[i], aggregators[i], feeTiers[i], toleranceBpsArr[i]);
        }
    }

    function _setFeed(address token, address aggregator, uint24 feeTier, uint16 toleranceBps) internal {
        require(token != address(0) && aggregator != address(0), "zero addr");
        require(feeTier == 500 || feeTier == 3000 || feeTier == 10000, "bad fee");
        require(toleranceBps <= 2000, "tolerance too high"); // <=20%

        uint8 dec = AggregatorV3Interface(aggregator).decimals();
        feeds[token] =
            FeedInfo({aggregator: aggregator, decimalsCache: dec, feeTier: feeTier, toleranceBps: toleranceBps});
        emit FeedSet(token, aggregator, dec, feeTier, toleranceBps);
    }

    // --- Admin: remove feed ---
    /**
     * @notice Removes price feed configuration for a token (owner only)
     * @dev After removal, swaps for this token will revert with FeedNotSet error.
     * Use this to disable support for a token without redeploying the contract.
     * @param token The ERC20 token address to remove from supported tokens
     */
    function removeFeed(address token) external onlyOwner {
        require(feeds[token].aggregator != address(0), "feed not set");
        delete feeds[token];
        emit FeedRemoved(token);
    }

    // --- Simplified ETH-only swap ---
    /**
     * @param token          ERC20 to buy (must have TOKEN/ETH feed configured).
     * @param slippageBps    Runtime slippage buffer (e.g., 200 = 2%).
     * @param deadline       Unix timestamp after which the transaction will revert.
     * @return amountOut     Tokens transferred to msg.sender.
     */
    function swapEthForToken(address token, uint16 slippageBps, uint256 deadline)
        external
        payable
        nonReentrant
        returns (uint256 amountOut)
    {
        if (msg.value == 0) revert NoEthSent();
        if (slippageBps > 10000) revert InvalidSlippage(); // Max 100%
        if (deadline < block.timestamp) revert("deadline expired");

        FeedInfo memory f = feeds[token];
        if (f.aggregator == address(0)) revert FeedNotSet();
        if (f.feeTier == 0) revert FeeNotSet();

        // 1) Read TOKEN/ETH price with staleness check
        (, int256 tokEthAns,, uint256 tokUpdatedAt,) = AggregatorV3Interface(f.aggregator).latestRoundData();
        if (tokEthAns <= 0) revert OracleBad();
        if (block.timestamp - tokUpdatedAt > MAX_ORACLE_STALENESS) revert OracleStale();
        uint256 tokEthPrice = uint256(tokEthAns);

        // 2) Compute expected tokens - standard TOKEN/ETH calculation
        uint256 expectedTokens;
        {
            uint8 tokenDec = IERC20(token).decimals();
            // TOKEN/ETH price means: tokEthPrice * 10^decimalsCache = tokens per 1 ETH
            // For msg.value ETH: expectedTokens = msg.value * tokEthPrice * 10^tokenDec / (1e18 * 10^decimalsCache)

            // Use precision scaling to avoid early division
            uint256 scaledNumerator = msg.value * tokEthPrice * (10 ** tokenDec);
            expectedTokens = scaledNumerator / (1e18 * (10 ** f.decimalsCache));
        }

        // 3) Conservative minOut using both user slippage and feed tolerance
        uint256 totalBps = uint256(slippageBps) + uint256(f.toleranceBps);
        if (totalBps > 10_000) totalBps = 10_000; // clamp
        uint256 minOut = expectedTokens * (10_000 - totalBps) / 10_000;

        // 4) Wrap ETH, approve, swap
        weth.deposit{value: msg.value}();
        if (!weth.approve(UNISWAP_V3_ROUTER, msg.value)) revert ApproveFailed();

        ISwapRouter.ExactInputSingleParams memory p = ISwapRouter.ExactInputSingleParams({
            tokenIn: WETH9_ADDR,
            tokenOut: token,
            fee: f.feeTier,
            recipient: address(this),
            deadline: deadline,
            amountIn: msg.value,
            amountOutMinimum: minOut,
            sqrtPriceLimitX96: 0
        });
        amountOut = router.exactInputSingle(p);

        // 5) Send tokens to caller
        if (!SafeTransfer.transfer(token, msg.sender, amountOut)) revert TransferFailed();

        emit Swapped(msg.sender, token, msg.value, amountOut, f.feeTier, minOut, tokEthPrice);
    }

    // --- View functions ---
    /**
     * @notice Returns the configuration for a given token
     * @param token The ERC20 token address to query
     * @return aggregator The Chainlink price feed address (zero if not configured)
     * @return decimals The cached decimal count from the price feed
     * @return feeTier The Uniswap V3 fee tier to use for swaps
     * @return toleranceBps The price tolerance in basis points
     */
    function getFeed(address token)
        external
        view
        returns (address aggregator, uint8 decimals, uint24 feeTier, uint16 toleranceBps)
    {
        FeedInfo memory x = feeds[token];
        return (x.aggregator, x.decimalsCache, x.feeTier, x.toleranceBps);
    }

    receive() external payable {
        revert();
    }
}
"
    },
    "lib/openzeppelin-contracts/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);
    }
}
"
    },
    "lib/openzeppelin-contracts/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;
    }
}
"
    },
    "lib/openzeppelin-contracts/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;
    }
}
"
    }
  },
  "settings": {
    "remappings": [
      "@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/",
      "erc4626-tests/=lib/openzeppelin-contracts/lib/erc4626-tests/",
      "forge-std/=lib/forge-std/src/",
      "halmos-cheatcodes/=lib/openzeppelin-contracts/lib/halmos-cheatcodes/src/",
      "openzeppelin-contracts/=lib/openzeppelin-contracts/"
    ],
    "optimizer": {
      "enabled": true,
      "runs": 200
    },
    "metadata": {
      "useLiteralContent": false,
      "bytecodeHash": "ipfs",
      "appendCBOR": true
    },
    "outputSelection": {
      "*": {
        "*": [
          "evm.bytecode",
          "evm.deployedBytecode",
          "devdoc",
          "userdoc",
          "metadata",
          "abi"
        ]
      }
    },
    "evmVersion": "prague",
    "viaIR": true
  }
}}