Contract Name:
StakingRewards
Contract Source Code:
File 1 of 1 : StakingRewards
// File: contracts/SafeMath.sol
pragma solidity ^0.8.11;
/**
* @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) {
require(b <= a, "SafeMath: subtraction overflow");
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-solidity/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) {
// 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;
}
/**
* @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) {
require(b != 0, "SafeMath: modulo by zero");
return a % b;
}
}
// File: contracts/StakingRewards.sol
//pragma solidity ^0.8.11;
//import "./ERC20Detailed.sol";
//import "./SafeERC20.sol";
//import "./ReentrancyGuard.sol";
// Inheritance
//import "./IStakingRewards.sol";
//import "./RewardsDistributionRecipient.sol";
//import "./Pausable.sol";
// https://docs.synthetix.io/contracts/source/interfaces/istakingrewards
interface IStakingRewards {
// Views
function balanceOf(address account) external view returns (uint256);
function earned(address account) external view returns (uint256);
function getRewardForDuration() external view returns (uint256);
function lastTimeRewardApplicable() external view returns (uint256);
function rewardPerToken() external view returns (uint256);
//function rewardsDistribution() external view returns (address);
//function rewardsToken() external view returns (address);
function totalSupply() external view returns (uint256);
// Mutative
function exit() external;
function getReward() external;
function stake(uint256 amount) external;
function withdraw(uint256 amount) external;
}
/**
* @dev Collection of functions related to the address type,
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* This test is non-exhaustive, and there may be false-negatives: during the
* execution of a contract's constructor, its address will be reported as
* not containing a contract.
*
* > It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*/
function isContract(address account) internal view returns (bool) {
// This method relies in 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 Interface of the ERC20 standard as defined in the EIP. Does not include
* the optional functions; to access them see `ERC20Detailed`.
*/
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.
*
* > 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);
}
/**
* @dev Optional functions from the ERC20 standard.
*/
abstract contract ERC20Detailed is IERC20 {
string private _name;
string private _symbol;
uint8 private _decimals;
/**
* @dev Sets the values for `name`, `symbol`, and `decimals`. All three of
* these values are immutable: they can only be set once during
* construction.
*/
constructor (string memory name_, string memory symbol_, uint8 decimals_) {
_name = name_;
_symbol = symbol_;
_decimals = decimals_;
}
/**
* @dev Returns the name of the token.
*/
function name() public view returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() public view returns (string memory) {
return _symbol;
}
/**
* @dev Returns the number of decimals used to get its user representation.
* For example, if `decimals` equals `2`, a balance of `505` tokens should
* be displayed to a user as `5,05` (`505 / 10 ** 2`).
*
* Tokens usually opt for a value of 18, imitating the relationship between
* Ether and Wei.
*
* > Note that this information is only used for _display_ purposes: it in
* no way affects any of the arithmetic of the contract, including
* `IERC20.balanceOf` and `IERC20.transfer`.
*/
function decimals() public view returns (uint8) {
return _decimals;
}
}
/**
* @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 ERC20;` 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));
}
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);
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.
// A Solidity high level call has three parts:
// 1. The target address is checked to verify it contains contract code
// 2. The call itself is made, and success asserted
// 3. The return value is decoded, which in turn checks the size of the returned data.
// solhint-disable-next-line max-line-length
require(address(token).isContract(), "SafeERC20: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = address(token).call(data);
require(success, "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");
}
}
}
// https://docs.synthetix.io/contracts/source/contracts/owned
contract Owned {
address public owner;
address public nominatedOwner;
constructor(address _owner) public {
require(_owner != address(0), "Owner address cannot be 0");
owner = _owner;
emit OwnerChanged(address(0), _owner);
}
function nominateNewOwner(address _owner) external onlyOwner {
nominatedOwner = _owner;
emit OwnerNominated(_owner);
}
function acceptOwnership() external {
require(msg.sender == nominatedOwner, "You must be nominated before you can accept ownership");
emit OwnerChanged(owner, nominatedOwner);
owner = nominatedOwner;
nominatedOwner = address(0);
}
modifier onlyOwner {
_onlyOwner();
_;
}
function _onlyOwner() private view {
require(msg.sender == owner, "Only the contract owner may perform this action");
}
event OwnerNominated(address newOwner);
event OwnerChanged(address oldOwner, address newOwner);
}
// https://docs.synthetix.io/contracts/source/contracts/pausable
abstract contract Pausable is Owned {
uint public lastPauseTime;
bool public paused;
constructor() internal {
// This contract is abstract, and thus cannot be instantiated directly
require(owner != address(0), "Owner must be set");
// Paused will be false, and lastPauseTime will be 0 upon initialisation
}
/**
* @notice Change the paused state of the contract
* @dev Only the contract owner may call this.
*/
function setPaused(bool _paused) external onlyOwner {
// Ensure we're actually changing the state before we do anything
if (_paused == paused) {
return;
}
// Set our paused state.
paused = _paused;
// If applicable, set the last pause time.
if (paused) {
lastPauseTime = block.timestamp;
}
// Let everyone know that our pause state has changed.
emit PauseChanged(paused);
}
event PauseChanged(bool isPaused);
modifier notPaused {
require(!paused, "This action cannot be performed while the contract is paused");
_;
}
}
// https://docs.synthetix.io/contracts/source/contracts/rewardsdistributionrecipient
abstract contract RewardsDistributionRecipient is Owned {
address public rewardsDistribution;
function notifyRewardAmount(uint256 reward) virtual external;
modifier onlyRewardsDistribution() {
require(msg.sender == rewardsDistribution, "Caller is not RewardsDistribution contract");
_;
}
function setRewardsDistribution(address _rewardsDistribution) external onlyOwner {
rewardsDistribution = _rewardsDistribution;
}
}
/**
* @dev Contract module that helps prevent reentrant calls to a function.
*
* Inheriting from `ReentrancyGuard` will make the `nonReentrant` modifier
* available, which can be aplied 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.
*/
abstract contract ReentrancyGuard {
/// @dev counter to allow mutex lock with only one SSTORE operation
uint256 private _guardCounter;
constructor () internal {
// The counter starts at one to prevent changing it from zero to a non-zero
// value, which is a more expensive operation.
_guardCounter = 1;
}
/**
* @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() {
_guardCounter += 1;
uint256 localCounter = _guardCounter;
_;
require(localCounter == _guardCounter, "ReentrancyGuard: reentrant call");
}
}
// https://docs.synthetix.io/contracts/source/contracts/stakingrewards
contract StakingRewards is IStakingRewards, RewardsDistributionRecipient, Pausable {
using SafeMath for uint256;
using SafeERC20 for IERC20;
/* ========== STATE VARIABLES ========== */
IERC20 public rewardsToken;
IERC20 public stakingToken;
uint256 public periodFinish = 0;
uint256 public rewardRate = 0;
uint256 public rewardsDuration = 7 days;
uint256 public lastUpdateTime;
uint256 public rewardPerTokenStored;
mapping(address => uint256) public userRewardPerTokenPaid;
mapping(address => uint256) public rewards;
uint256 private _totalSupply;
mapping(address => uint256) private _balances;
uint256 private _guardCounter;
/* ========== CONSTRUCTOR ========== */
constructor(
address _owner,
address _rewardsDistribution,
address _rewardsToken,
address _stakingToken
) public Owned(_owner) {
rewardsToken = IERC20(_rewardsToken);
stakingToken = IERC20(_stakingToken);
rewardsDistribution = _rewardsDistribution;
_guardCounter = 1;
}
/* ========== VIEWS ========== */
function totalSupply() external view returns (uint256) {
return _totalSupply;
}
function balanceOf(address account) external view returns (uint256) {
return _balances[account];
}
function lastTimeRewardApplicable() public view returns (uint256) {
return block.timestamp < periodFinish ? block.timestamp : periodFinish;
}
function rewardPerToken() public view returns (uint256) {
if (_totalSupply == 0) {
return rewardPerTokenStored;
}
return
rewardPerTokenStored.add(
lastTimeRewardApplicable().sub(lastUpdateTime).mul(rewardRate).mul(1e18).div(_totalSupply)
);
}
function earned(address account) public view returns (uint256) {
return _balances[account].mul(rewardPerToken().sub(userRewardPerTokenPaid[account])).div(1e18).add(rewards[account]);
}
function getRewardForDuration() external view returns (uint256) {
return rewardRate.mul(rewardsDuration);
}
/* ========== MUTATIVE FUNCTIONS ========== */
function stake(uint256 amount) external nonReentrant notPaused 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);
}
function withdraw(uint256 amount) public 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);
}
function getReward() public 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);
}
}
function exit() external {
withdraw(_balances[msg.sender]);
getReward();
}
/* ========== RESTRICTED FUNCTIONS ========== */
function notifyRewardAmount(uint256 reward) override external 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);
}
// Added to support recovering LP Rewards from other systems such as BAL to be distributed to holders
function recoverERC20(address tokenAddress, uint256 tokenAmount) external onlyOwner {
require(tokenAddress != address(stakingToken), "Cannot withdraw the staking token");
IERC20(tokenAddress).safeTransfer(owner, tokenAmount);
emit Recovered(tokenAddress, tokenAmount);
}
function setRewardsDuration(uint256 _rewardsDuration) external onlyOwner {
require(
block.timestamp > periodFinish,
"Previous rewards period must be complete before changing the duration for the new period"
);
rewardsDuration = _rewardsDuration;
emit RewardsDurationUpdated(rewardsDuration);
}
/* ========== MODIFIERS ========== */
modifier updateReward(address account) {
rewardPerTokenStored = rewardPerToken();
lastUpdateTime = lastTimeRewardApplicable();
if (account != address(0)) {
rewards[account] = earned(account);
userRewardPerTokenPaid[account] = rewardPerTokenStored;
}
_;
}
modifier nonReentrant() {
_guardCounter += 1;
uint256 localCounter = _guardCounter;
_;
require(localCounter == _guardCounter, "ReentrancyGuard: reentrant call");
}
/* ========== EVENTS ========== */
event RewardAdded(uint256 reward);
event Staked(address indexed user, uint256 amount);
event Withdrawn(address indexed user, uint256 amount);
event RewardPaid(address indexed user, uint256 reward);
event RewardsDurationUpdated(uint256 newDuration);
event Recovered(address token, uint256 amount);
}