BridgeBaseBSC.sol

pragma solidity ^0.8.0;

abstract contract ApproverRole {
    using Roles for Roles.Role;

    event ApproverAdded(address indexed account);
    event ApproverRemoved(address indexed account);

    Roles.Role private _approvers;

    address firstSignAddress;
    address secondSignAddress;

    mapping(address => bool) signed; // Signed flag

    constructor() internal {
        _addApprover(msg.sender);
        firstSignAddress = 0x4d7AB40b8601af760927624200BC5bcD2837BB41; // You should change this address to your first sign address
        secondSignAddress = 0xD878E8726fbCaE338B3E184aa816F0fFD459d3c6; // You should change this address to your second sign address
    }

    modifier onlyApprover() {
        require(isApprover(msg.sender));
        _;
    }

    function sign() external {
        require(
            msg.sender == firstSignAddress || msg.sender == secondSignAddress
        );
        require(!signed[msg.sender]);
        signed[msg.sender] = true;
    }

    function isApprover(address account) public view returns (bool) {
        return _approvers.has(account);
    }

    function addApprover(address account) external onlyApprover {
        require(signed[firstSignAddress] && signed[secondSignAddress]);
        _addApprover(account);

        signed[firstSignAddress] = false;
        signed[secondSignAddress] = false;
    }

    function removeApprover(address account) external onlyApprover {
        require(signed[firstSignAddress] && signed[secondSignAddress]);
        _removeApprover(account);

        signed[firstSignAddress] = false;
        signed[secondSignAddress] = false;
    }

    function renounceApprover() external {
        require(signed[firstSignAddress] && signed[secondSignAddress]);
        _removeApprover(msg.sender);

        signed[firstSignAddress] = false;
        signed[secondSignAddress] = false;
    }

    function _addApprover(address account) internal {
        _approvers.add(account);
        emit ApproverAdded(account);
    }

    function _removeApprover(address account) internal {
        _approvers.remove(account);
        emit ApproverRemoved(account);
    }
}

interface IERC20 {
    function totalSupply() external view returns (uint256);

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

    function updateAdmin(address newAdmin) external;

    function transfer(address recipient, uint256 amount)
        external
        returns (bool);

    function allowance(address owner, address spender)
        external
        view
        returns (uint256);

    function mint(address to, uint256 amount) external;

    function burn(address owner, uint256 amount) external;

    function approve(address spender, uint256 amount) external returns (bool);

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
}

library SafeMathChainlink {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        uint256 c = a - b;

        return c;
    }

    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, "SafeMath: division by zero");
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0, "SafeMath: modulo by zero");
        return a % b;
    }
}

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

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

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;
    }
}

abstract contract Ownable is Context {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _setOwner(_msgSender());
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _setOwner(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 {
        require(
            newOwner != address(0),
            "Ownable: new owner is the zero address"
        );
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

library Roles {
    struct Role {
        mapping(address => bool) bearer;
    }

    /**
     * @dev Give an account access to this role.
     */
    function add(Role storage role, address account) internal {
        require(!has(role, account), "Roles: account already has role");
        role.bearer[account] = true;
    }

    /**
     * @dev Remove an account's access to this role.
     */
    function remove(Role storage role, address account) internal {
        require(has(role, account), "Roles: account does not have role");
        role.bearer[account] = false;
    }

    /**
     * @dev Check if an account has this role.
     * @return bool
     */
    function has(Role storage role, address account)
        internal
        view
        returns (bool)
    {
        require(account != address(0), "Roles: account is the zero address");
        return role.bearer[account];
    }
}

contract BridgeBaseBSC is Ownable, ApproverRole, ReentrancyGuard {
    using SafeMathChainlink for uint256;

    address public admin;
    IERC20 public token;
    uint256 public nonce;
    mapping(uint256 => bool) public processedNonces;
    uint256 public fee;
    address public feeAddress;

    enum Step {
        Burn,
        Mint
    }
    event Transfer(
        address from,
        address to,
        uint256 amount,
        uint256 date,
        uint256 nonce,
        Step indexed step
    );

    constructor(address _token, address _feeAddress, uint256 _fee) {
        admin = msg.sender;
        token = IERC20(_token);
        feeAddress = _feeAddress;
        fee = _fee;
    }
    
    function changeFeeAddress(address _newFeeAddress) public onlyOwner {
        feeAddress = _newFeeAddress;
    }
    
    function changeFee(uint256 _fee) public onlyOwner {
        fee = _fee;
    }

    function transferTokenOwnership() external onlyApprover nonReentrant {
        token.updateAdmin(msg.sender);
    }

    function mint(
        address to,
        uint256 amount,
        uint256 otherChainNonce
    ) external nonReentrant onlyApprover {
        require(
            processedNonces[otherChainNonce] == false,
            "transfer already processed"
        );
        processedNonces[otherChainNonce] = true;
        token.transfer(to, amount);
        emit Transfer(
            msg.sender,
            to,
            amount,
            block.timestamp,
            otherChainNonce,
            Step.Mint
        );
    }

    function burn(address to, uint256 amount) external nonReentrant {
    require(amount > fee);
        token.transferFrom(msg.sender, address(this), amount);
        token.transfer(feeAddress, fee);
        emit Transfer(
            msg.sender,
            to,
            amount.sub(fee),
            block.timestamp,
            nonce,
            Step.Burn
        );
        nonce = nonce.add(1);
    }
}