Contract Source Code:
pragma solidity ^0.6.0;
import '@openzeppelin/contracts/math/Math.sol';
import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import '@openzeppelin/contracts/token/ERC20/SafeERC20.sol';
import '@openzeppelin/contracts/utils/ReentrancyGuard.sol';
import {ICurve} from './curve/Curve.sol';
import {IOracle} from './interfaces/IOracle.sol';
import {IBoardroom} from './interfaces/IBoardroom.sol';
import {IBasisAsset} from './interfaces/IBasisAsset.sol';
import {ISimpleERCFund} from './interfaces/ISimpleERCFund.sol';
import {Babylonian} from './lib/Babylonian.sol';
import {FixedPoint} from './lib/FixedPoint.sol';
import {Safe112} from './lib/Safe112.sol';
import {Operator} from './owner/Operator.sol';
import {Epoch} from './utils/Epoch.sol';
import {ContractGuard} from './utils/ContractGuard.sol';
/**
* @title Basis Cash Treasury contract
* @notice Monetary policy logic to adjust supplies of basis cash assets
* @author Summer Smith & Rick Sanchez
*/
contract Treasury is ContractGuard, Epoch {
using FixedPoint for *;
using SafeERC20 for IERC20;
using Address for address;
using SafeMath for uint256;
using Safe112 for uint112;
/* ========== STATE VARIABLES ========== */
// ========== FLAGS
bool public migrated = false;
bool public initialized = false;
// ========== CORE
address public fund;
address public cash;
address public bond;
address public share;
address public curve;
address public boardroom;
address public boardroomLp; // boardroom support lp staking
address public bondOracle;
address public seigniorageOracle;
// ========== PARAMS
uint256 public cashPriceOne;
uint256 public lastBondOracleEpoch = 0;
uint256 public bondCap = 0;
uint256 public accumulatedSeigniorage = 0;
uint256 public fundAllocationRate = 18; // ‰
uint256 public boardroomAllocationRate = 30; // boardroom: 30%, boardroomLp: 70%
/* ========== CONSTRUCTOR ========== */
constructor(
address _cash,
address _bond,
address _share,
address _bondOracle,
address _seigniorageOracle,
address _boardroom,
address _boardroomLp, //boardroom for lp
address _fund,
address _curve,
uint256 _startTime
)
public Epoch(8 hours, _startTime, 0)
{
cash = _cash;
bond = _bond;
share = _share;
curve = _curve;
bondOracle = _bondOracle;
seigniorageOracle = _seigniorageOracle;
boardroom = _boardroom;
boardroomLp = _boardroomLp;
fund = _fund;
cashPriceOne = 10**18;
}
/* =================== Modifier =================== */
modifier checkMigration {
require(!migrated, 'Treasury: migrated');
_;
}
modifier checkOperator {
require(
IBasisAsset(cash).operator() == address(this) &&
IBasisAsset(bond).operator() == address(this) &&
IBasisAsset(share).operator() == address(this) &&
Operator(boardroom).operator() == address(this) &&
Operator(boardroomLp).operator() == address(this),
'Treasury: need more permission'
);
_;
}
modifier updatePrice {
_;
_updateCashPrice();
}
/* ========== VIEW FUNCTIONS ========== */
// budget
function getReserve() public view returns (uint256) {
return accumulatedSeigniorage;
}
function circulatingSupply() public view returns (uint256) {
return IERC20(cash).totalSupply().sub(accumulatedSeigniorage);
}
function getCeilingPrice() public view returns (uint256) {
return ICurve(curve).calcCeiling(circulatingSupply());
}
// oracle
function getBondOraclePrice() public view returns (uint256) {
return _getCashPrice(bondOracle);
}
function getSeigniorageOraclePrice() public view returns (uint256) {
return _getCashPrice(seigniorageOracle);
}
function _getCashPrice(address oracle) internal view returns (uint256) {
try IOracle(oracle).consult(cash, 1e18) returns (uint256 price) {
return price;
} catch {
revert('Treasury: failed to consult cash price from the oracle');
}
}
/* ========== GOVERNANCE ========== */
// MIGRATION
function initialize() public checkOperator {
require(!initialized, 'Treasury: initialized');
// set accumulatedSeigniorage to it's balance
accumulatedSeigniorage = IERC20(cash).balanceOf(address(this));
initialized = true;
emit Initialized(msg.sender, block.number);
}
function migrate(address target) public onlyOperator checkOperator {
require(!migrated, 'Treasury: migrated');
// cash
Operator(cash).transferOperator(target);
Operator(cash).transferOwnership(target);
IERC20(cash).transfer(target, IERC20(cash).balanceOf(address(this)));
// bond
Operator(bond).transferOperator(target);
Operator(bond).transferOwnership(target);
IERC20(bond).transfer(target, IERC20(bond).balanceOf(address(this)));
// share
Operator(share).transferOperator(target);
Operator(share).transferOwnership(target);
IERC20(share).transfer(target, IERC20(share).balanceOf(address(this)));
migrated = true;
emit Migration(target);
}
// FUND
function setFund(address newFund) public onlyOperator {
address oldFund = fund;
fund = newFund;
emit ContributionPoolChanged(msg.sender, oldFund, newFund);
}
function setFundAllocationRate(uint256 newRate) public onlyOperator {
uint256 oldRate = fundAllocationRate;
fundAllocationRate = newRate;
emit ContributionPoolRateChanged(msg.sender, oldRate, newRate);
}
// ORACLE
function setBondOracle(address newOracle) public onlyOperator {
address oldOracle = bondOracle;
bondOracle = newOracle;
emit BondOracleChanged(msg.sender, oldOracle, newOracle);
}
function setSeigniorageOracle(address newOracle) public onlyOperator {
address oldOracle = seigniorageOracle;
seigniorageOracle = newOracle;
emit SeigniorageOracleChanged(msg.sender, oldOracle, newOracle);
}
// TWEAK
function setCeilingCurve(address newCurve) public onlyOperator {
address oldCurve = newCurve;
curve = newCurve;
emit CeilingCurveChanged(msg.sender, oldCurve, newCurve);
}
function setBoardroomAllocationRate(uint256 newRate) public onlyOperator {
require(newRate <= 100, 'invalid boardroom rate');
uint256 oldRate = boardroomAllocationRate;
boardroomAllocationRate = newRate;
emit BoardroomRateChanged(msg.sender, oldRate, newRate);
}
/* ========== MUTABLE FUNCTIONS ========== */
function _updateConversionLimit(uint256 cashPrice) internal {
uint256 currentEpoch = Epoch(bondOracle).getLastEpoch(); // lastest update time
if (lastBondOracleEpoch != currentEpoch) {
uint256 percentage = cashPriceOne.sub(cashPrice);
uint256 bondSupply = IERC20(bond).totalSupply();
bondCap = circulatingSupply().mul(percentage).div(1e18);
bondCap = bondCap.sub(Math.min(bondCap, bondSupply));
lastBondOracleEpoch = currentEpoch;
}
}
function _updateCashPrice() internal {
if (Epoch(bondOracle).callable()) {
try IOracle(bondOracle).update() {} catch {}
}
if (Epoch(seigniorageOracle).callable()) {
try IOracle(seigniorageOracle).update() {} catch {}
}
}
function buyBonds(uint256 amount, uint256 targetPrice)
external
onlyOneBlock
checkMigration
checkStartTime
checkOperator
updatePrice
{
require(amount > 0, 'Treasury: cannot purchase bonds with zero amount');
uint256 cashPrice = _getCashPrice(bondOracle);
require(cashPrice <= targetPrice, 'Treasury: cash price moved');
require(
cashPrice < cashPriceOne, // price < $1
'Treasury: cashPrice not eligible for bond purchase'
);
_updateConversionLimit(cashPrice);
amount = Math.min(amount, bondCap.mul(cashPrice).div(1e18));
require(amount > 0, 'Treasury: amount exceeds bond cap');
bondCap = bondCap.sub(amount.mul(1e18).div(cashPrice));
IBasisAsset(cash).burnFrom(msg.sender, amount);
IBasisAsset(bond).mint(msg.sender, amount.mul(1e18).div(cashPrice));
emit BoughtBonds(msg.sender, amount);
}
function redeemBonds(uint256 amount)
external
onlyOneBlock
checkMigration
checkStartTime
checkOperator
updatePrice
{
require(amount > 0, 'Treasury: cannot redeem bonds with zero amount');
uint256 cashPrice = _getCashPrice(bondOracle);
require(
cashPrice > getCeilingPrice(), // price > $1.05
'Treasury: cashPrice not eligible for bond purchase'
);
require(
IERC20(cash).balanceOf(address(this)) >= amount,
'Treasury: treasury has no more budget'
);
accumulatedSeigniorage = accumulatedSeigniorage.sub(
Math.min(accumulatedSeigniorage, amount)
);
IBasisAsset(bond).burnFrom(msg.sender, amount);
IERC20(cash).safeTransfer(msg.sender, amount);
emit RedeemedBonds(msg.sender, amount);
}
function allocateSeigniorage()
external
onlyOneBlock
checkMigration
checkStartTime
checkEpoch
checkOperator
{
_updateCashPrice();
uint256 cashPrice = _getCashPrice(seigniorageOracle);
if (cashPrice <= getCeilingPrice()) {
return; // just advance epoch instead revert
}
// circulating supply
uint256 percentage = cashPrice.sub(cashPriceOne);
uint256 seigniorage = circulatingSupply().mul(percentage).div(1e18);
IBasisAsset(cash).mint(address(this), seigniorage);
// ======================== BIP-3
uint256 fundReserve = seigniorage.mul(fundAllocationRate).div(1000);
if (fundReserve > 0) {
IERC20(cash).safeApprove(fund, fundReserve);
ISimpleERCFund(fund).deposit(
cash,
fundReserve,
'Treasury: Seigniorage Allocation'
);
emit ContributionPoolFunded(now, fundReserve);
}
seigniorage = seigniorage.sub(fundReserve);
// ======================== BIP-4
uint256 treasuryReserve =
Math.min(
seigniorage,
IERC20(bond).totalSupply() > accumulatedSeigniorage
? IERC20(bond).totalSupply().sub(accumulatedSeigniorage)
: 0
);
if (treasuryReserve > 0) {
accumulatedSeigniorage = accumulatedSeigniorage.add(
treasuryReserve
);
emit TreasuryFunded(now, treasuryReserve);
}
// boardroom
uint256 boardroomReserve = seigniorage.sub(treasuryReserve);
if (boardroomReserve > 0) {
// boardroom : boardroomLp = 3:7
uint256 boardroomReserve3 =
boardroomReserve.mul(boardroomAllocationRate).div(100);
IERC20(cash).safeApprove(boardroom, boardroomReserve3);
IBoardroom(boardroom).allocateSeigniorage(boardroomReserve3);
emit BoardroomFunded(now, boardroomReserve);
emit BoardroomFunded(boardroom, now, boardroomReserve3);
uint256 boardroomLpReserve7 =
boardroomReserve.sub(boardroomReserve3);
IERC20(cash).safeApprove(boardroomLp, boardroomLpReserve7);
IBoardroom(boardroomLp).allocateSeigniorage(boardroomLpReserve7);
emit BoardroomFunded(boardroomLp, now, boardroomLpReserve7);
}
}
function sendCash(uint amount) public {
require(msg.sender == boardroom || msg.sender == boardroomLp, 'Invalid sender');
accumulatedSeigniorage = accumulatedSeigniorage.add(amount);
IERC20(cash).safeTransferFrom(msg.sender, address(this), amount);
}
/* ========== EVENTS ========== */
// GOV
event Initialized(address indexed executor, uint256 at);
event Migration(address indexed target);
event ContributionPoolChanged(
address indexed operator,
address oldFund,
address newFund
);
event ContributionPoolRateChanged(
address indexed operator,
uint256 oldRate,
uint256 newRate
);
event BondOracleChanged(
address indexed operator,
address oldOracle,
address newOracle
);
event SeigniorageOracleChanged(
address indexed operator,
address oldOracle,
address newOracle
);
event CeilingCurveChanged(
address indexed operator,
address oldCurve,
address newCurve
);
event BoardroomRateChanged(
address indexed operator,
uint256 oldRate,
uint256 newRate
);
// CORE
event RedeemedBonds(address indexed from, uint256 amount);
event BoughtBonds(address indexed from, uint256 amount);
event TreasuryFunded(uint256 timestamp, uint256 seigniorage);
event BoardroomFunded(uint256 timestamp, uint256 seigniorage);
event BoardroomFunded(
address boardroom,
uint256 timestamp,
uint256 seigniorage
);
event ContributionPoolFunded(uint256 timestamp, uint256 seigniorage);
}
pragma solidity ^0.6.0;
interface ICurve {
function minSupply() external view returns (uint256);
function maxSupply() external view returns (uint256);
function minCeiling() external view returns (uint256);
function maxCeiling() external view returns (uint256);
function calcCeiling(uint256 _supply) external view returns (uint256);
}
abstract contract Curve is ICurve {
/* ========== EVENTS ========== */
event MinSupplyChanged(
address indexed operator,
uint256 _old,
uint256 _new
);
event MaxSupplyChanged(
address indexed operator,
uint256 _old,
uint256 _new
);
event MinCeilingChanged(
address indexed operator,
uint256 _old,
uint256 _new
);
event MaxCeilingChanged(
address indexed operator,
uint256 _old,
uint256 _new
);
/* ========== STATE VARIABLES ========== */
uint256 public override minSupply;
uint256 public override maxSupply;
uint256 public override minCeiling;
uint256 public override maxCeiling;
/* ========== GOVERNANCE ========== */
function setMinSupply(uint256 _newMinSupply) public virtual {
uint256 oldMinSupply = minSupply;
minSupply = _newMinSupply;
emit MinSupplyChanged(msg.sender, oldMinSupply, _newMinSupply);
}
function setMaxSupply(uint256 _newMaxSupply) public virtual {
uint256 oldMaxSupply = maxSupply;
maxSupply = _newMaxSupply;
emit MaxSupplyChanged(msg.sender, oldMaxSupply, _newMaxSupply);
}
function setMinCeiling(uint256 _newMinCeiling) public virtual {
uint256 oldMinCeiling = _newMinCeiling;
minCeiling = _newMinCeiling;
emit MinCeilingChanged(msg.sender, oldMinCeiling, _newMinCeiling);
}
function setMaxCeiling(uint256 _newMaxCeiling) public virtual {
uint256 oldMaxCeiling = _newMaxCeiling;
maxCeiling = _newMaxCeiling;
emit MaxCeilingChanged(msg.sender, oldMaxCeiling, _newMaxCeiling);
}
function calcCeiling(uint256 _supply)
external
view
virtual
override
returns (uint256);
}
pragma solidity ^0.6.0;
interface IBasisAsset {
function mint(address recipient, uint256 amount) external returns (bool);
function burn(uint256 amount) external;
function burnFrom(address from, uint256 amount) external;
function isOperator() external returns (bool);
function operator() external view returns (address);
}
pragma solidity ^0.6.0;
interface IBoardroom {
function allocateSeigniorage(uint256 amount) external;
}
pragma solidity ^0.6.0;
interface IOracle {
function update() external;
function consult(address token, uint256 amountIn)
external
view
returns (uint256 amountOut);
// function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestamp);
}
pragma solidity ^0.6.0;
interface ISimpleERCFund {
function deposit(
address token,
uint256 amount,
string memory reason
) external;
function withdraw(
address token,
uint256 amount,
address to,
string memory reason
) external;
}
pragma solidity ^0.6.0;
library Babylonian {
function sqrt(uint256 y) internal pure returns (uint256 z) {
if (y > 3) {
z = y;
uint256 x = y / 2 + 1;
while (x < z) {
z = x;
x = (y / x + x) / 2;
}
} else if (y != 0) {
z = 1;
}
// else z = 0
}
}
pragma solidity ^0.6.0;
import './Babylonian.sol';
// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))
library FixedPoint {
// range: [0, 2**112 - 1]
// resolution: 1 / 2**112
struct uq112x112 {
uint224 _x;
}
// range: [0, 2**144 - 1]
// resolution: 1 / 2**112
struct uq144x112 {
uint256 _x;
}
uint8 private constant RESOLUTION = 112;
uint256 private constant Q112 = uint256(1) << RESOLUTION;
uint256 private constant Q224 = Q112 << RESOLUTION;
// encode a uint112 as a UQ112x112
function encode(uint112 x) internal pure returns (uq112x112 memory) {
return uq112x112(uint224(x) << RESOLUTION);
}
// encodes a uint144 as a UQ144x112
function encode144(uint144 x) internal pure returns (uq144x112 memory) {
return uq144x112(uint256(x) << RESOLUTION);
}
// divide a UQ112x112 by a uint112, returning a UQ112x112
function div(uq112x112 memory self, uint112 x)
internal
pure
returns (uq112x112 memory)
{
require(x != 0, 'FixedPoint: DIV_BY_ZERO');
return uq112x112(self._x / uint224(x));
}
// multiply a UQ112x112 by a uint, returning a UQ144x112
// reverts on overflow
function mul(uq112x112 memory self, uint256 y)
internal
pure
returns (uq144x112 memory)
{
uint256 z;
require(
y == 0 || (z = uint256(self._x) * y) / y == uint256(self._x),
'FixedPoint: MULTIPLICATION_OVERFLOW'
);
return uq144x112(z);
}
// returns a UQ112x112 which represents the ratio of the numerator to the denominator
// equivalent to encode(numerator).div(denominator)
function fraction(uint112 numerator, uint112 denominator)
internal
pure
returns (uq112x112 memory)
{
require(denominator > 0, 'FixedPoint: DIV_BY_ZERO');
return uq112x112((uint224(numerator) << RESOLUTION) / denominator);
}
// decode a UQ112x112 into a uint112 by truncating after the radix point
function decode(uq112x112 memory self) internal pure returns (uint112) {
return uint112(self._x >> RESOLUTION);
}
// decode a UQ144x112 into a uint144 by truncating after the radix point
function decode144(uq144x112 memory self) internal pure returns (uint144) {
return uint144(self._x >> RESOLUTION);
}
// take the reciprocal of a UQ112x112
function reciprocal(uq112x112 memory self)
internal
pure
returns (uq112x112 memory)
{
require(self._x != 0, 'FixedPoint: ZERO_RECIPROCAL');
return uq112x112(uint224(Q224 / self._x));
}
// square root of a UQ112x112
function sqrt(uq112x112 memory self)
internal
pure
returns (uq112x112 memory)
{
return uq112x112(uint224(Babylonian.sqrt(uint256(self._x)) << 56));
}
}
pragma solidity ^0.6.0;
library Safe112 {
function add(uint112 a, uint112 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, 'Safe112: addition overflow');
return c;
}
function sub(uint112 a, uint112 b) internal pure returns (uint256) {
return sub(a, b, 'Safe112: subtraction overflow');
}
function sub(
uint112 a,
uint112 b,
string memory errorMessage
) internal pure returns (uint112) {
require(b <= a, errorMessage);
uint112 c = a - b;
return c;
}
function mul(uint112 a, uint112 b) internal pure returns (uint256) {
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b, 'Safe112: multiplication overflow');
return c;
}
function div(uint112 a, uint112 b) internal pure returns (uint256) {
return div(a, b, 'Safe112: division by zero');
}
function div(
uint112 a,
uint112 b,
string memory errorMessage
) internal pure returns (uint112) {
// Solidity only automatically asserts when dividing by 0
require(b > 0, errorMessage);
uint112 c = a / b;
return c;
}
function mod(uint112 a, uint112 b) internal pure returns (uint256) {
return mod(a, b, 'Safe112: modulo by zero');
}
function mod(
uint112 a,
uint112 b,
string memory errorMessage
) internal pure returns (uint112) {
require(b != 0, errorMessage);
return a % b;
}
}
pragma solidity ^0.6.0;
import '@openzeppelin/contracts/GSN/Context.sol';
import '@openzeppelin/contracts/access/Ownable.sol';
contract Operator is Context, Ownable {
address private _operator;
event OperatorTransferred(
address indexed previousOperator,
address indexed newOperator
);
constructor() internal {
_operator = _msgSender();
emit OperatorTransferred(address(0), _operator);
}
function operator() public view returns (address) {
return _operator;
}
modifier onlyOperator() {
require(
_operator == msg.sender,
'operator: caller is not the operator'
);
_;
}
function isOperator() public view returns (bool) {
return _msgSender() == _operator;
}
function transferOperator(address newOperator_) public onlyOwner {
_transferOperator(newOperator_);
}
function _transferOperator(address newOperator_) internal {
require(
newOperator_ != address(0),
'operator: zero address given for new operator'
);
emit OperatorTransferred(address(0), newOperator_);
_operator = newOperator_;
}
}
pragma solidity ^0.6.12;
contract ContractGuard {
mapping(uint256 => mapping(address => bool)) private _status;
function checkSameOriginReentranted() internal view returns (bool) {
return _status[block.number][tx.origin];
}
function checkSameSenderReentranted() internal view returns (bool) {
return _status[block.number][msg.sender];
}
modifier onlyOneBlock() {
require(
!checkSameOriginReentranted(),
'ContractGuard: one block, one function'
);
require(
!checkSameSenderReentranted(),
'ContractGuard: one block, one function'
);
_;
_status[block.number][tx.origin] = true;
_status[block.number][msg.sender] = true;
}
}
pragma solidity ^0.6.0;
import '@openzeppelin/contracts/math/Math.sol';
import '@openzeppelin/contracts/math/SafeMath.sol';
import '../owner/Operator.sol';
contract Epoch is Operator {
using SafeMath for uint256;
uint256 private period;
uint256 private startTime;
uint256 private lastExecutedAt;
/* ========== CONSTRUCTOR ========== */
constructor(
uint256 _period,
uint256 _startTime,
uint256 _startEpoch
) public {
require(_startTime > block.timestamp, 'Epoch: invalid start time');
period = _period;
startTime = _startTime;
lastExecutedAt = startTime.add(_startEpoch.mul(period));
}
/* ========== Modifier ========== */
modifier checkStartTime {
require(now >= startTime, 'Epoch: not started yet');
_;
}
modifier checkEpoch {
require(now > startTime, 'Epoch: not started yet');
require(callable(), 'Epoch: not allowed');
_;
lastExecutedAt = block.timestamp;
}
/* ========== VIEW FUNCTIONS ========== */
function callable() public view returns (bool) {
return getCurrentEpoch() >= getNextEpoch();
}
// epoch
function getLastEpoch() public view returns (uint256) {
return lastExecutedAt.sub(startTime).div(period);
}
function getCurrentEpoch() public view returns (uint256) {
return Math.max(startTime, block.timestamp).sub(startTime).div(period);
}
function getNextEpoch() public view returns (uint256) {
if (startTime == lastExecutedAt) {
return getLastEpoch();
}
return getLastEpoch().add(1);
}
function nextEpochPoint() public view returns (uint256) {
return startTime.add(getNextEpoch().mul(period));
}
// params
function getPeriod() public view returns (uint256) {
return period;
}
function getStartTime() public view returns (uint256) {
return startTime;
}
/* ========== GOVERNANCE ========== */
function setPeriod(uint256 _period) external onlyOperator {
period = _period;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/*
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with GSN meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address payable) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes memory) {
this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
return msg.data;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import "../GSN/Context.sol";
/**
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
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 () internal {
address msgSender = _msgSender();
_owner = msgSender;
emit OwnershipTransferred(address(0), msgSender);
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view 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 {
emit OwnershipTransferred(_owner, address(0));
_owner = 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");
emit OwnershipTransferred(_owner, newOwner);
_owner = newOwner;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @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;
/**
* @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 ^0.6.0;
/**
* @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 ^0.6.0;
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 ^0.6.2;
/**
* @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 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 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");
return _functionCallWithValue(target, data, value, errorMessage);
}
function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
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);
}
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @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].
*/
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;
}
}