Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
/**
* @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 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) {
return sub(a, b, "SafeMath: subtraction overflow");
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* 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);
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 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) {
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;
}
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
/**
* @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 0.6.12;
import "../libraries/math/SafeMath.sol";
import "../libraries/token/IERC20.sol";
import "./interfaces/INslpManager.sol";
import "./interfaces/IRewardTracker.sol";
import "./interfaces/IRewardTracker.sol";
interface ISettingsManager {
function cooldownDuration() external view returns (uint256);
}
// provide a way to transfer staked NSLP tokens by unstaking from the sender
// and staking for the receiver
contract StakedNslp {
using SafeMath for uint256;
string public constant name = "StakedNslp";
string public constant symbol = "sNSLP";
uint8 public constant decimals = 18;
address public nslp;
INslpManager public nslpManager;
ISettingsManager public nslpSettingsManager;
address public stakedNslpTracker;
address public feeNslpTracker;
mapping(address => mapping(address => uint256)) public allowances;
event Approval(address indexed owner, address indexed spender, uint256 value);
constructor(
address _nslp,
INslpManager _nslpManager,
ISettingsManager _nslpSettingsManager,
address _stakedNslpTracker,
address _feeNslpTracker
) public {
nslp = _nslp;
nslpManager = _nslpManager;
nslpSettingsManager = _nslpSettingsManager;
stakedNslpTracker = _stakedNslpTracker;
feeNslpTracker = _feeNslpTracker;
}
function allowance(address _owner, address _spender) external view returns (uint256) {
return allowances[_owner][_spender];
}
function approve(address _spender, uint256 _amount) external returns (bool) {
_approve(msg.sender, _spender, _amount);
return true;
}
function transfer(address _recipient, uint256 _amount) external returns (bool) {
_transfer(msg.sender, _recipient, _amount);
return true;
}
function transferFrom(address _sender, address _recipient, uint256 _amount) external returns (bool) {
uint256 nextAllowance = allowances[_sender][msg.sender].sub(_amount, "StakedNslp: transfer amount exceeds allowance");
_approve(_sender, msg.sender, nextAllowance);
_transfer(_sender, _recipient, _amount);
return true;
}
function balanceOf(address _account) external view returns (uint256) {
return IRewardTracker(feeNslpTracker).depositBalances(_account, nslp);
}
function totalSupply() external view returns (uint256) {
return IERC20(stakedNslpTracker).totalSupply();
}
function _approve(address _owner, address _spender, uint256 _amount) private {
require(_owner != address(0), "StakedNslp: approve from the zero address");
require(_spender != address(0), "StakedNslp: approve to the zero address");
allowances[_owner][_spender] = _amount;
emit Approval(_owner, _spender, _amount);
}
function _transfer(address _sender, address _recipient, uint256 _amount) private {
require(_sender != address(0), "StakedNslp: transfer from the zero address");
require(_recipient != address(0), "StakedNslp: transfer to the zero address");
require(
nslpManager.lastStakedAt(_sender).add(nslpSettingsManager.cooldownDuration()) <= block.timestamp,
"StakedNslp: cooldown duration not yet passed"
);
IRewardTracker(stakedNslpTracker).unstakeForAccount(_sender, feeNslpTracker, _amount, _sender);
IRewardTracker(feeNslpTracker).unstakeForAccount(_sender, nslp, _amount, _sender);
IRewardTracker(feeNslpTracker).stakeForAccount(_sender, _recipient, nslp, _amount);
IRewardTracker(stakedNslpTracker).stakeForAccount(_recipient, _recipient, feeNslpTracker, _amount);
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
interface INslpManager {
function unstake(address _account, address _tokenOut, uint256 _nslpAmount) external returns (uint256);
function stake(address _account, address _token, uint256 _amount) external returns (uint256);
function deposit(address _account, address _token, uint256 _amount) external;
function lastStakedAt(address _account) external view returns (uint256);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
interface IRewardTracker {
function depositBalances(address _account, address _depositToken) external view returns (uint256);
function stakedAmounts(address _account) external view returns (uint256);
function updateRewards() external;
function stake(address _depositToken, uint256 _amount) external;
function stakeForAccount(address _fundingAccount, address _account, address _depositToken, uint256 _amount) external;
function unstake(address _depositToken, uint256 _amount) external;
function unstakeForAccount(address _account, address _depositToken, uint256 _amount, address _receiver) external;
function tokensPerInterval() external view returns (uint256);
function claim(address _receiver) external returns (uint256);
function claimForAccount(address _account, address _receiver) external returns (uint256);
function claimable(address _account) external view returns (uint256);
function averageStakedAmounts(address _account) external view returns (uint256);
function cumulativeRewards(address _account) external view returns (uint256);
}