Added timelock contract

contracts/SafeMath.sol

@@ -0,0 +1,186 @@
+pragma solidity ^0.5.16;
+
+// From https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/math/Math.sol
+// Subject to the MIT license.
+
+/**
+ * @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, 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 addition of two unsigned integers, reverting with custom message on overflow.
+     *
+     * Counterpart to Solidity's `+` operator.
+     *
+     * Requirements:
+     * - Addition cannot overflow.
+     */
+    function add(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
+        uint256 c = a + b;
+        require(c >= a, errorMessage);
+
+        return c;
+    }
+
+    /**
+     * @dev Returns the subtraction of two unsigned integers, reverting on underflow (when the result is negative).
+     *
+     * Counterpart to Solidity's `-` operator.
+     *
+     * Requirements:
+     * - Subtraction cannot underflow.
+     */
+    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
+        return sub(a, b, "SafeMath: subtraction underflow");
+    }
+
+    /**
+     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on underflow (when the result is negative).
+     *
+     * Counterpart to Solidity's `-` operator.
+     *
+     * Requirements:
+     * - Subtraction cannot underflow.
+     */
+    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
+        require(b <= a, errorMessage);
+        uint256 c = a - b;
+
+        return c;
+    }
+
+    /**
+     * @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) {
+        // 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 0;
+        }
+
+        uint256 c = a * b;
+        require(c / a == b, "SafeMath: multiplication overflow");
+
+        return c;
+    }
+
+    /**
+     * @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, string memory errorMessage) internal pure returns (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 0;
+        }
+
+        uint256 c = a * b;
+        require(c / a == b, errorMessage);
+
+        return c;
+    }
+
+    /**
+     * @dev Returns the integer division of two unsigned integers.
+     * Reverts 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) {
+        return div(a, b, "SafeMath: division by zero");
+    }
+
+    /**
+     * @dev Returns the integer division of two unsigned integers.
+     * Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
+        // Solidity only automatically asserts when dividing by 0
+        require(b > 0, errorMessage);
+        uint256 c = a / b;
+        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
+
+        return c;
+    }
+
+    /**
+     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
+     * Reverts 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) {
+        return mod(a, b, "SafeMath: modulo by zero");
+    }
+
+    /**
+     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
+     * Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
+        require(b != 0, errorMessage);
+        return a % b;
+    }
+}

contracts/Timelock.sol

@@ -0,0 +1,112 @@
+pragma solidity ^0.5.16;
+
+import "./SafeMath.sol";
+
+contract Timelock {
+    using SafeMath for uint;
+
+    event NewAdmin(address indexed newAdmin);
+    event NewPendingAdmin(address indexed newPendingAdmin);
+    event NewDelay(uint indexed newDelay);
+    event CancelTransaction(bytes32 indexed txHash, address indexed target, uint value, string signature,  bytes data, uint eta);
+    event ExecuteTransaction(bytes32 indexed txHash, address indexed target, uint value, string signature,  bytes data, uint eta);
+    event QueueTransaction(bytes32 indexed txHash, address indexed target, uint value, string signature, bytes data, uint eta);
+
+    uint public constant GRACE_PERIOD = 14 days;
+    uint public constant MINIMUM_DELAY = 2 days;
+    uint public constant MAXIMUM_DELAY = 30 days;
+
+    address public admin;
+    address public pendingAdmin;
+    uint public delay;
+
+    mapping (bytes32 => bool) public queuedTransactions;
+
+
+    constructor(address admin_, uint delay_) public {
+
+        require(delay_ >= MINIMUM_DELAY, "Timelock::constructor: Delay must exceed minimum delay.");
+        require(delay_ <= MAXIMUM_DELAY, "Timelock::setDelay: Delay must not exceed maximum delay.");
+
+        admin = admin_;
+        delay = delay_;
+    }
+
+    function() external payable { }
+
+    function setDelay(uint delay_) public {
+        require(msg.sender == address(this), "Timelock::setDelay: Call must come from Timelock.");
+        require(delay_ >= MINIMUM_DELAY, "Timelock::setDelay: Delay must exceed minimum delay.");
+        require(delay_ <= MAXIMUM_DELAY, "Timelock::setDelay: Delay must not exceed maximum delay.");
+        delay = delay_;
+
+        emit NewDelay(delay);
+    }
+
+    function acceptAdmin() public {
+        require(msg.sender == pendingAdmin, "Timelock::acceptAdmin: Call must come from pendingAdmin.");
+        admin = msg.sender;
+        pendingAdmin = address(0);
+
+        emit NewAdmin(admin);
+    }
+
+    function setPendingAdmin(address pendingAdmin_) public {
+        require(msg.sender == address(this), "Timelock::setPendingAdmin: Call must come from Timelock.");
+        pendingAdmin = pendingAdmin_;
+
+        emit NewPendingAdmin(pendingAdmin);
+    }
+
+    function queueTransaction(address target, uint value, string memory signature, bytes memory data, uint eta) public returns (bytes32) {
+        require(msg.sender == admin, "Timelock::queueTransaction: Call must come from admin.");
+        require(eta >= getBlockTimestamp().add(delay), "Timelock::queueTransaction: Estimated execution block must satisfy delay.");
+
+        bytes32 txHash = keccak256(abi.encode(target, value, signature, data, eta));
+        queuedTransactions[txHash] = true;
+
+        emit QueueTransaction(txHash, target, value, signature, data, eta);
+        return txHash;
+    }
+
+    function cancelTransaction(address target, uint value, string memory signature, bytes memory data, uint eta) public {
+        require(msg.sender == admin, "Timelock::cancelTransaction: Call must come from admin.");
+
+        bytes32 txHash = keccak256(abi.encode(target, value, signature, data, eta));
+        queuedTransactions[txHash] = false;
+
+        emit CancelTransaction(txHash, target, value, signature, data, eta);
+    }
+
+    function executeTransaction(address target, uint value, string memory signature, bytes memory data, uint eta) public payable returns (bytes memory) {
+        require(msg.sender == admin, "Timelock::executeTransaction: Call must come from admin.");
+
+        bytes32 txHash = keccak256(abi.encode(target, value, signature, data, eta));
+        require(queuedTransactions[txHash], "Timelock::executeTransaction: Transaction hasn't been queued.");
+        require(getBlockTimestamp() >= eta, "Timelock::executeTransaction: Transaction hasn't surpassed time lock.");
+        require(getBlockTimestamp() <= eta.add(GRACE_PERIOD), "Timelock::executeTransaction: Transaction is stale.");
+
+        queuedTransactions[txHash] = false;
+
+        bytes memory callData;
+
+        if (bytes(signature).length == 0) {
+            callData = data;
+        } else {
+            callData = abi.encodePacked(bytes4(keccak256(bytes(signature))), data);
+        }
+
+        // solium-disable-next-line security/no-call-value
+        (bool success, bytes memory returnData) = target.call.value(value)(callData);
+        require(success, "Timelock::executeTransaction: Transaction execution reverted.");
+
+        emit ExecuteTransaction(txHash, target, value, signature, data, eta);
+
+        return returnData;
+    }
+
+    function getBlockTimestamp() internal view returns (uint) {
+        // solium-disable-next-line security/no-block-members
+        return block.timestamp;
+    }
+}