Contract

Contract Source Code (Solidity Standard Json-Input format)

IDE

• Blockscan IDE
• 🤖 Code ReaderBeta
• Remix IDE

More Options

• Similar
• Sol2Uml
• Submit Audit
• Compare

// SPDX-License-Identifier: MIT
pragma solidity ^0.7.6;

import "../openzeppelin-solidity-3.4.0/contracts/math/Math.sol";
import "../openzeppelin-solidity-3.4.0/contracts/math/SafeMath.sol";
import "../openzeppelin-solidity-3.4.0/contracts/token/ERC20/SafeERC20.sol";
import "../openzeppelin-solidity-3.4.0/contracts/utils/ReentrancyGuard.sol";

// Inheritance
import "./interfaces/IStakingRewards.sol";
import "./RewardsDistributionRecipient.sol";

contract StakingRewards is IStakingRewards, RewardsDistributionRecipient, ReentrancyGuard {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    /* ========== STATE VARIABLES ========== */

    /// The token staking rewards will be paid in.
    IERC20 public rewardsToken;
    /// The token which must be staked to earn rewards.
    IERC20 public stakingToken;
    /// The time at which reward distribution will be complete.
    uint256 public periodFinish = 0;
    /// The rate at which rewards will be distributed.
    uint256 public rewardRate = 0;
    /// How long rewards will be distributed after the staking period begins.
    uint256 public rewardsDuration = 135 days;
    /// The last time rewardPerTokenStored was updated.
    uint256 public lastUpdateTime;
    /// The lastest snapshot of the amount of reward allocated to each staked token.
    uint256 public rewardPerTokenStored;

    /// How much reward-per-token has been paid out to each user who has withdrawn their stake.
    mapping(address => uint256) public userRewardPerTokenPaid;
    /// How much reward each user has earned.
    mapping(address => uint256) public rewards;

    uint256 private _totalSupply;
    mapping(address => uint256) private _balances;

    /* ========== CONSTRUCTOR ========== */

    /// Deploy a new StakingRewards contract with the specified parameters. (This should only be done by the StakingRewardsFactory.)
    constructor(
        address _rewardsDistribution,
        address _rewardsToken,
        address _stakingToken
    ) {
        rewardsToken = IERC20(_rewardsToken);
        stakingToken = IERC20(_stakingToken);
        rewardsDistribution = _rewardsDistribution;
    }

    /* ========== VIEWS ========== */

    /// Returns the total number of LP tokens staked.
    function totalSupply() external view override returns (uint256) {
        return _totalSupply;
    }

    /// Returns the total number of LP tokens staked by a given address.
    function balanceOf(address account) external view override returns (uint256) {
        return _balances[account];
    }

    /// Returns the last time for which a rewards have already been earned.
    function lastTimeRewardApplicable() public view override returns (uint256) {
        return Math.min(block.timestamp, periodFinish);
    }

    /// Returns the current amount of reward allocated per staked LP token.
    function rewardPerToken() public view override returns (uint256) {
        if (_totalSupply == 0) {
            return rewardPerTokenStored;
        }
        return
            rewardPerTokenStored.add(
                lastTimeRewardApplicable().sub(lastUpdateTime).mul(rewardRate).mul(1e18).div(_totalSupply)
            );
    }

    /// Returns the total reward earnings associated with a given address.
    function earned(address account) public view override returns (uint256) {
        return _balances[account].mul(rewardPerToken().sub(userRewardPerTokenPaid[account])).div(1e18).add(rewards[account]);
    }

    /// Returns the total reward amount.
    function getRewardForDuration() external view override returns (uint256) {
        return rewardRate.mul(rewardsDuration);
    }

    /* ========== MUTATIVE FUNCTIONS ========== */

    /// Stake a number of LP tokens to earn rewards, using a signed permit instead of a balance approval.
    function stakeWithPermit(uint256 amount, uint deadline, uint8 v, bytes32 r, bytes32 s) external nonReentrant updateReward(msg.sender) {
        require(amount > 0, "Cannot stake 0");
        _totalSupply = _totalSupply.add(amount);
        _balances[msg.sender] = _balances[msg.sender].add(amount);

        // permit
        IUniswapV2ERC20(address(stakingToken)).permit(msg.sender, address(this), amount, deadline, v, r, s);

        stakingToken.safeTransferFrom(msg.sender, address(this), amount);
        emit Staked(msg.sender, amount);
    }

    /// Stake a number of LP tokens to earn rewards.
    function stake(uint256 amount) external override nonReentrant updateReward(msg.sender) {
        require(amount > 0, "Cannot stake 0");
        _totalSupply = _totalSupply.add(amount);
        _balances[msg.sender] = _balances[msg.sender].add(amount);
        stakingToken.safeTransferFrom(msg.sender, address(this), amount);
        emit Staked(msg.sender, amount);
    }

    /// Withdraw a number of LP tokens.
    function withdraw(uint256 amount) public override nonReentrant updateReward(msg.sender) {
        require(amount > 0, "Cannot withdraw 0");
        _totalSupply = _totalSupply.sub(amount);
        _balances[msg.sender] = _balances[msg.sender].sub(amount);
        stakingToken.safeTransfer(msg.sender, amount);
        emit Withdrawn(msg.sender, amount);
    }

    /// Transfer the caller's earned rewards.
    function getReward() public override nonReentrant updateReward(msg.sender) {
        uint256 reward = rewards[msg.sender];
        if (reward > 0) {
            rewards[msg.sender] = 0;
            rewardsToken.safeTransfer(msg.sender, reward);
            emit RewardPaid(msg.sender, reward);
        }
    }

    /// Withdraw all staked LP tokens and any pending rewards.
    function exit() external override {
        withdraw(_balances[msg.sender]);
        getReward();
    }

    /* ========== RESTRICTED FUNCTIONS ========== */

    /// Called by the StakingRewardsFactory to begin reward distribution.
    function notifyRewardAmount(uint256 reward) external override onlyRewardsDistribution updateReward(address(0)) {
        if (block.timestamp >= periodFinish) {
            rewardRate = reward.div(rewardsDuration);
        } else {
            uint256 remaining = periodFinish.sub(block.timestamp);
            uint256 leftover = remaining.mul(rewardRate);
            rewardRate = reward.add(leftover).div(rewardsDuration);
        }

        // Ensure the provided reward amount is not more than the balance in the contract.
        // This keeps the reward rate in the right range, preventing overflows due to
        // very high values of rewardRate in the earned and rewardsPerToken functions;
        // Reward + leftover must be less than 2^256 / 10^18 to avoid overflow.
        uint balance = rewardsToken.balanceOf(address(this));
        require(rewardRate <= balance.div(rewardsDuration), "Provided reward too high");

        lastUpdateTime = block.timestamp;
        periodFinish = block.timestamp.add(rewardsDuration);
        emit RewardAdded(reward);
    }

    /* ========== MODIFIERS ========== */

    modifier updateReward(address account) {
        rewardPerTokenStored = rewardPerToken();
        lastUpdateTime = lastTimeRewardApplicable();
        if (account != address(0)) {
            rewards[account] = earned(account);
            userRewardPerTokenPaid[account] = rewardPerTokenStored;
        }
        _;
    }

    /* ========== EVENTS ========== */

    /// Emitted when the StakingRewardsFactory has allocated a reward balance to a StakingRewards contract, starting the staking period.
    event RewardAdded(uint256 reward);
    /// Emitted when a user stakes their LP tokens.
    event Staked(address indexed user, uint256 amount);
    /// Emitted when a user withdraws their LP tokens.
    event Withdrawn(address indexed user, uint256 amount);
    /// Emitted when a user has been paid a reward.
    event RewardPaid(address indexed user, uint256 reward);
}

interface IUniswapV2ERC20 {
    /// Allows a user to permit a contract to access their tokens by signing a permit.
    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    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;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
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));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        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));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @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 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;

    constructor () internal {
        _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 make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

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

        _;

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

pragma solidity >=0.4.24;


interface IStakingRewards {
    // Views
    function lastTimeRewardApplicable() external view returns (uint256);

    function rewardPerToken() external view returns (uint256);

    function earned(address account) external view returns (uint256);

    function getRewardForDuration() external view returns (uint256);

    function totalSupply() external view returns (uint256);

    function balanceOf(address account) external view returns (uint256);

    // Mutative

    function stake(uint256 amount) external;

    function withdraw(uint256 amount) external;

    function getReward() external;

    function exit() external;
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.7.6;

abstract contract RewardsDistributionRecipient {
    address public rewardsDistribution;

    function notifyRewardAmount(uint256 reward) external virtual;

    modifier onlyRewardsDistribution() {
        require(msg.sender == rewardsDistribution, "Caller is not RewardsDistribution contract");
        _;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @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);
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

{
  "optimizer": {
    "enabled": true,
    "runs": 100000
  },
  "outputSelection": {
    "*": {
      "*": [
        "evm.bytecode",
        "evm.deployedBytecode",
        "devdoc",
        "userdoc",
        "metadata",
        "abi"
      ]
    }
  },
  "metadata": {
    "useLiteralContent": true
  },
  "libraries": {}
}

• No Contract Security Audit Submitted- Submit Audit Here

[{"inputs":[{"internalType":"address","name":"_rewardsDistribution","type":"address"},{"internalType":"address","name":"_rewardsToken","type":"address"},{"internalType":"address","name":"_stakingToken","type":"address"}],"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"uint256","name":"reward","type":"uint256"}],"name":"RewardAdded","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"user","type":"address"},{"indexed":false,"internalType":"uint256","name":"reward","type":"uint256"}],"name":"RewardPaid","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"user","type":"address"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"Staked","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"user","type":"address"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"Withdrawn","type":"event"},{"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"earned","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"exit","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"getReward","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"getRewardForDuration","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"lastTimeRewardApplicable","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"lastUpdateTime","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"reward","type":"uint256"}],"name":"notifyRewardAmount","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"periodFinish","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"rewardPerToken","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"rewardPerTokenStored","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"rewardRate","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"","type":"address"}],"name":"rewards","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"rewardsDistribution","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"rewardsDuration","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"rewardsToken","outputs":[{"internalType":"contract IERC20","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"stake","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amount","type":"uint256"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"stakeWithPermit","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"stakingToken","outputs":[{"internalType":"contract IERC20","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"totalSupply","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"","type":"address"}],"name":"userRewardPerTokenPaid","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"withdraw","outputs":[],"stateMutability":"nonpayable","type":"function"}]

0x608060405234801561001057600080fd5b50600436106101815760003560e01c80637b0a47ee116100d8578063cd3daf9d1161008c578063e9fad8ee11610066578063e9fad8ee14610346578063ebe2b12b1461034e578063ecd9ba821461035657610181565b8063cd3daf9d1461032e578063d1af0c7d14610336578063df136d651461033e57610181565b80638b876347116100bd5780638b876347146102d6578063a694fc3a14610309578063c8f33c911461032657610181565b80637b0a47ee146102c657806380faa57d146102ce57610181565b8063386a95251161013a5780633fc6df6e116101145780633fc6df6e1461025a57806370a082311461028b57806372f702f3146102be57610181565b8063386a95251461022d5780633c6b16ab146102355780633d18b9121461025257610181565b806318160ddd1161016b57806318160ddd146101fe5780631c1f78eb146102065780632e1a7d4d1461020e57610181565b80628cc262146101865780630700037d146101cb575b600080fd5b6101b96004803603602081101561019c57600080fd5b503573ffffffffffffffffffffffffffffffffffffffff1661038e565b60408051918252519081900360200190f35b6101b9600480360360208110156101e157600080fd5b503573ffffffffffffffffffffffffffffffffffffffff16610426565b6101b9610438565b6101b961043f565b61022b6004803603602081101561022457600080fd5b503561045d565b005b6101b9610659565b61022b6004803603602081101561024b57600080fd5b503561065f565b61022b610913565b610262610a8a565b6040805173ffffffffffffffffffffffffffffffffffffffff9092168252519081900360200190f35b6101b9600480360360208110156102a157600080fd5b503573ffffffffffffffffffffffffffffffffffffffff16610aa6565b610262610ace565b6101b9610aea565b6101b9610af0565b6101b9600480360360208110156102ec57600080fd5b503573ffffffffffffffffffffffffffffffffffffffff16610afe565b61022b6004803603602081101561031f57600080fd5b5035610b10565b6101b9610d0d565b6101b9610d13565b610262610d61565b6101b9610d7d565b61022b610d83565b6101b9610da6565b61022b600480360360a081101561036c57600080fd5b5080359060208101359060ff6040820135169060608101359060800135610dac565b73ffffffffffffffffffffffffffffffffffffffff81166000908152600a60209081526040808320546009909252822054610420919061041a90670de0b6b3a764000090610414906103e8906103e2610d13565b9061105e565b73ffffffffffffffffffffffffffffffffffffffff88166000908152600c6020526040902054906110d5565b9061114f565b906111d0565b92915050565b600a6020526000908152604090205481565b600b545b90565b60006104586006546005546110d590919063ffffffff16565b905090565b600260015414156104cf57604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152601f60248201527f5265656e7472616e637947756172643a207265656e7472616e742063616c6c00604482015290519081900360640190fd5b6002600155336104dd610d13565b6008556104e8610af0565b60075573ffffffffffffffffffffffffffffffffffffffff811615610549576105108161038e565b73ffffffffffffffffffffffffffffffffffffffff82166000908152600a60209081526040808320939093556008546009909152919020555b600082116105b857604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152601160248201527f43616e6e6f742077697468647261772030000000000000000000000000000000604482015290519081900360640190fd5b600b546105c5908361105e565b600b55336000908152600c60205260409020546105e2908361105e565b336000818152600c602052604090209190915560035461061b9173ffffffffffffffffffffffffffffffffffffffff9091169084611244565b60408051838152905133917f7084f5476618d8e60b11ef0d7d3f06914655adb8793e28ff7f018d4c76d505d5919081900360200190a2505060018055565b60065481565b60005473ffffffffffffffffffffffffffffffffffffffff1633146106cf576040517f08c379a000000000000000000000000000000000000000000000000000000000815260040180806020018281038252602a81526020018061173c602a913960400191505060405180910390fd5b60006106d9610d13565b6008556106e4610af0565b60075573ffffffffffffffffffffffffffffffffffffffff8116156107455761070c8161038e565b73ffffffffffffffffffffffffffffffffffffffff82166000908152600a60209081526040808320939093556008546009909152919020555b60045442106107645760065461075c90839061114f565b6005556107a7565b600454600090610774904261105e565b9050600061078d600554836110d590919063ffffffff16565b6006549091506107a19061041486846111d0565b60055550505b600254604080517f70a08231000000000000000000000000000000000000000000000000000000008152306004820152905160009273ffffffffffffffffffffffffffffffffffffffff16916370a08231916024808301926020929190829003018186803b15801561081857600080fd5b505afa15801561082c573d6000803e3d6000fd5b505050506040513d602081101561084257600080fd5b505160065490915061085590829061114f565b60055411156108c557604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152601860248201527f50726f76696465642072657761726420746f6f20686967680000000000000000604482015290519081900360640190fd5b4260078190556006546108d891906111d0565b6004556040805184815290517fde88a922e0d3b88b24e9623efeb464919c6bf9f66857a65e2bfcf2ce87a9433d9181900360200190a1505050565b6002600154141561098557604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152601f60248201527f5265656e7472616e637947756172643a207265656e7472616e742063616c6c00604482015290519081900360640190fd5b600260015533610993610d13565b60085561099e610af0565b60075573ffffffffffffffffffffffffffffffffffffffff8116156109ff576109c68161038e565b73ffffffffffffffffffffffffffffffffffffffff82166000908152600a60209081526040808320939093556008546009909152919020555b336000908152600a60205260409020548015610a8257336000818152600a6020526040812055600254610a4b9173ffffffffffffffffffffffffffffffffffffffff9091169083611244565b60408051828152905133917fe2403640ba68fed3a2f88b7557551d1993f84b99bb10ff833f0cf8db0c5e0486919081900360200190a25b505060018055565b60005473ffffffffffffffffffffffffffffffffffffffff1681565b73ffffffffffffffffffffffffffffffffffffffff166000908152600c602052604090205490565b60035473ffffffffffffffffffffffffffffffffffffffff1681565b60055481565b6000610458426004546112d6565b60096020526000908152604090205481565b60026001541415610b8257604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152601f60248201527f5265656e7472616e637947756172643a207265656e7472616e742063616c6c00604482015290519081900360640190fd5b600260015533610b90610d13565b600855610b9b610af0565b60075573ffffffffffffffffffffffffffffffffffffffff811615610bfc57610bc38161038e565b73ffffffffffffffffffffffffffffffffffffffff82166000908152600a60209081526040808320939093556008546009909152919020555b60008211610c6b57604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152600e60248201527f43616e6e6f74207374616b652030000000000000000000000000000000000000604482015290519081900360640190fd5b600b54610c7890836111d0565b600b55336000908152600c6020526040902054610c9590836111d0565b336000818152600c6020526040902091909155600354610ccf9173ffffffffffffffffffffffffffffffffffffffff9091169030856112ec565b60408051838152905133917f9e71bc8eea02a63969f509818f2dafb9254532904319f9dbda79b67bd34a5f3d919081900360200190a2505060018055565b60075481565b6000600b5460001415610d29575060085461043c565b610458610d58600b54610414670de0b6b3a7640000610d52600554610d526007546103e2610af0565b906110d5565b600854906111d0565b60025473ffffffffffffffffffffffffffffffffffffffff1681565b60085481565b336000908152600c6020526040902054610d9c9061045d565b610da4610913565b565b60045481565b60026001541415610e1e57604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152601f60248201527f5265656e7472616e637947756172643a207265656e7472616e742063616c6c00604482015290519081900360640190fd5b600260015533610e2c610d13565b600855610e37610af0565b60075573ffffffffffffffffffffffffffffffffffffffff811615610e9857610e5f8161038e565b73ffffffffffffffffffffffffffffffffffffffff82166000908152600a60209081526040808320939093556008546009909152919020555b60008611610f0757604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152600e60248201527f43616e6e6f74207374616b652030000000000000000000000000000000000000604482015290519081900360640190fd5b600b54610f1490876111d0565b600b55336000908152600c6020526040902054610f3190876111d0565b336000818152600c60205260408082209390935560035483517fd505accf0000000000000000000000000000000000000000000000000000000081526004810193909352306024840152604483018a90526064830189905260ff8816608484015260a4830187905260c48301869052925173ffffffffffffffffffffffffffffffffffffffff9093169263d505accf9260e480820193929182900301818387803b158015610fde57600080fd5b505af1158015610ff2573d6000803e3d6000fd5b505060035461101c925073ffffffffffffffffffffffffffffffffffffffff1690503330896112ec565b60408051878152905133917f9e71bc8eea02a63969f509818f2dafb9254532904319f9dbda79b67bd34a5f3d919081900360200190a250506001805550505050565b6000828211156110cf57604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152601e60248201527f536166654d6174683a207375627472616374696f6e206f766572666c6f770000604482015290519081900360640190fd5b50900390565b6000826110e457506000610420565b828202828482816110f157fe5b0414611148576040517f08c379a000000000000000000000000000000000000000000000000000000000815260040180806020018281038252602181526020018061171b6021913960400191505060405180910390fd5b9392505050565b60008082116111bf57604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152601a60248201527f536166654d6174683a206469766973696f6e206279207a65726f000000000000604482015290519081900360640190fd5b8183816111c857fe5b049392505050565b60008282018381101561114857604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152601b60248201527f536166654d6174683a206164646974696f6e206f766572666c6f770000000000604482015290519081900360640190fd5b6040805173ffffffffffffffffffffffffffffffffffffffff8416602482015260448082018490528251808303909101815260649091019091526020810180517bffffffffffffffffffffffffffffffffffffffffffffffffffffffff167fa9059cbb000000000000000000000000000000000000000000000000000000001790526112d1908490611387565b505050565b60008183106112e55781611148565b5090919050565b6040805173ffffffffffffffffffffffffffffffffffffffff80861660248301528416604482015260648082018490528251808303909101815260849091019091526020810180517bffffffffffffffffffffffffffffffffffffffffffffffffffffffff167f23b872dd00000000000000000000000000000000000000000000000000000000179052611381908590611387565b50505050565b60006113e9826040518060400160405280602081526020017f5361666545524332303a206c6f772d6c6576656c2063616c6c206661696c65648152508573ffffffffffffffffffffffffffffffffffffffff1661145f9092919063ffffffff16565b8051909150156112d15780806020019051602081101561140857600080fd5b50516112d1576040517f08c379a000000000000000000000000000000000000000000000000000000000815260040180806020018281038252602a815260200180611766602a913960400191505060405180910390fd5b606061146e8484600085611476565b949350505050565b6060824710156114d1576040517f08c379a00000000000000000000000000000000000000000000000000000000081526004018080602001828103825260268152602001806116f56026913960400191505060405180910390fd5b6114da85611630565b61154557604080517f08c379a000000000000000000000000000000000000000000000000000000000815260206004820152601d60248201527f416464726573733a2063616c6c20746f206e6f6e2d636f6e7472616374000000604482015290519081900360640190fd5b6000808673ffffffffffffffffffffffffffffffffffffffff1685876040518082805190602001908083835b602083106115ae57805182527fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe09092019160209182019101611571565b6001836020036101000a03801982511681845116808217855250505050505090500191505060006040518083038185875af1925050503d8060008114611610576040519150601f19603f3d011682016040523d82523d6000602084013e611615565b606091505b5091509150611625828286611636565b979650505050505050565b3b151590565b60608315611645575081611148565b8251156116555782518084602001fd5b816040517f08c379a00000000000000000000000000000000000000000000000000000000081526004018080602001828103825283818151815260200191508051906020019080838360005b838110156116b95781810151838201526020016116a1565b50505050905090810190601f1680156116e65780820380516001836020036101000a031916815260200191505b509250505060405180910390fdfe416464726573733a20696e73756666696369656e742062616c616e636520666f722063616c6c536166654d6174683a206d756c7469706c69636174696f6e206f766572666c6f7743616c6c6572206973206e6f742052657761726473446973747269627574696f6e20636f6e74726163745361666545524332303a204552433230206f7065726174696f6e20646964206e6f742073756363656564a264697066735822122006ae1e43629c2c3e5925ddfd344e62147c7731de75d96ead157773a31aaa0bd164736f6c63430007060033