Contract Source Code:
File 1 of 1 : xKNC
// File: @openzeppelin/contracts/GSN/Context.sol
pragma solidity ^0.5.0;
/*
* @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.
*/
contract Context {
// Empty internal constructor, to prevent people from mistakenly deploying
// an instance of this contract, which should be used via inheritance.
constructor () internal { }
// solhint-disable-previous-line no-empty-blocks
function _msgSender() internal view returns (address payable) {
return msg.sender;
}
function _msgData() internal view returns (bytes memory) {
this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
return msg.data;
}
}
// File: @openzeppelin/contracts/token/ERC20/IERC20.sol
pragma solidity ^0.5.0;
/**
* @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.
*
* 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);
}
// File: @openzeppelin/contracts/math/SafeMath.sol
pragma solidity ^0.5.0;
/**
* @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.
*
* _Available since v2.4.0._
*/
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.
*
* _Available since v2.4.0._
*/
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.
*
* _Available since v2.4.0._
*/
function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
}
// File: @openzeppelin/contracts/token/ERC20/ERC20.sol
pragma solidity ^0.5.0;
/**
* @dev Implementation of the {IERC20} interface.
*
* This implementation is agnostic to the way tokens are created. This means
* that a supply mechanism has to be added in a derived contract using {_mint}.
* For a generic mechanism see {ERC20Mintable}.
*
* TIP: For a detailed writeup see our guide
* https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
*
* We have followed general OpenZeppelin guidelines: functions revert instead
* of returning `false` on failure. This behavior is nonetheless conventional
* and does not conflict with the expectations of ERC20 applications.
*
* Additionally, an {Approval} event is emitted on calls to {transferFrom}.
* This allows applications to reconstruct the allowance for all accounts just
* by listening to said events. Other implementations of the EIP may not emit
* these events, as it isn't required by the specification.
*
* Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
* functions have been added to mitigate the well-known issues around setting
* allowances. See {IERC20-approve}.
*/
contract ERC20 is Context, IERC20 {
using SafeMath for uint256;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowances;
uint256 private _totalSupply;
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
function balanceOf(address account) public view returns (uint256) {
return _balances[account];
}
/**
* @dev See {IERC20-transfer}.
*
* Requirements:
*
* - `recipient` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address recipient, uint256 amount) public returns (bool) {
_transfer(_msgSender(), recipient, amount);
return true;
}
/**
* @dev See {IERC20-allowance}.
*/
function allowance(address owner, address spender) public view returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See {IERC20-approve}.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public returns (bool) {
_approve(_msgSender(), spender, amount);
return true;
}
/**
* @dev See {IERC20-transferFrom}.
*
* Emits an {Approval} event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of {ERC20};
*
* Requirements:
* - `sender` and `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
* - the caller must have allowance for `sender`'s tokens of at least
* `amount`.
*/
function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
return true;
}
/**
* @dev Atomically increases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
return true;
}
/**
* @dev Atomically decreases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `spender` must have allowance for the caller of at least
* `subtractedValue`.
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
return true;
}
/**
* @dev Moves tokens `amount` from `sender` to `recipient`.
*
* This is internal function is equivalent to {transfer}, and can be used to
* e.g. implement automatic token fees, slashing mechanisms, etc.
*
* Emits a {Transfer} event.
*
* Requirements:
*
* - `sender` cannot be the zero address.
* - `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
*/
function _transfer(address sender, address recipient, uint256 amount) internal {
require(sender != address(0), "ERC20: transfer from the zero address");
require(recipient != address(0), "ERC20: transfer to the zero address");
_balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
_balances[recipient] = _balances[recipient].add(amount);
emit Transfer(sender, recipient, amount);
}
/** @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* Emits a {Transfer} event with `from` set to the zero address.
*
* Requirements
*
* - `to` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal {
require(account != address(0), "ERC20: mint to the zero address");
_totalSupply = _totalSupply.add(amount);
_balances[account] = _balances[account].add(amount);
emit Transfer(address(0), account, amount);
}
/**
* @dev Destroys `amount` tokens from `account`, reducing the
* total supply.
*
* Emits a {Transfer} event with `to` set to the zero address.
*
* Requirements
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
*/
function _burn(address account, uint256 amount) internal {
require(account != address(0), "ERC20: burn from the zero address");
_balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
_totalSupply = _totalSupply.sub(amount);
emit Transfer(account, address(0), amount);
}
/**
* @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
*
* This is internal function is equivalent to `approve`, and can be used to
* e.g. set automatic allowances for certain subsystems, etc.
*
* Emits an {Approval} event.
*
* Requirements:
*
* - `owner` cannot be the zero address.
* - `spender` cannot be the zero address.
*/
function _approve(address owner, address spender, uint256 amount) internal {
require(owner != address(0), "ERC20: approve from the zero address");
require(spender != address(0), "ERC20: approve to the zero address");
_allowances[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
/**
* @dev Destroys `amount` tokens from `account`.`amount` is then deducted
* from the caller's allowance.
*
* See {_burn} and {_approve}.
*/
function _burnFrom(address account, uint256 amount) internal {
_burn(account, amount);
_approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance"));
}
}
// File: @openzeppelin/contracts/utils/Address.sol
pragma solidity ^0.5.5;
/**
* @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) {
// According to EIP-1052, 0x0 is the value returned for not-yet created accounts
// and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
// for accounts without code, i.e. `keccak256('')`
bytes32 codehash;
bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
// solhint-disable-next-line no-inline-assembly
assembly { codehash := extcodehash(account) }
return (codehash != accountHash && codehash != 0x0);
}
/**
* @dev Converts an `address` into `address payable`. Note that this is
* simply a type cast: the actual underlying value is not changed.
*
* _Available since v2.4.0._
*/
function toPayable(address account) internal pure returns (address payable) {
return address(uint160(account));
}
/**
* @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].
*
* _Available since v2.4.0._
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
// solhint-disable-next-line avoid-call-value
(bool success, ) = recipient.call.value(amount)("");
require(success, "Address: unable to send value, recipient may have reverted");
}
}
// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol
pragma solidity ^0.5.0;
/**
* @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, "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.
// 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");
}
}
}
// File: @openzeppelin/contracts/token/ERC20/ERC20Detailed.sol
pragma solidity ^0.5.0;
/**
* @dev Optional functions from the ERC20 standard.
*/
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) public {
_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: 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;
}
}
// File: @openzeppelin/contracts/access/Roles.sol
pragma solidity ^0.5.0;
/**
* @title Roles
* @dev Library for managing addresses assigned to a Role.
*/
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];
}
}
// File: @openzeppelin/contracts/access/roles/PauserRole.sol
pragma solidity ^0.5.0;
contract PauserRole is Context {
using Roles for Roles.Role;
event PauserAdded(address indexed account);
event PauserRemoved(address indexed account);
Roles.Role private _pausers;
constructor () internal {
_addPauser(_msgSender());
}
modifier onlyPauser() {
require(isPauser(_msgSender()), "PauserRole: caller does not have the Pauser role");
_;
}
function isPauser(address account) public view returns (bool) {
return _pausers.has(account);
}
function addPauser(address account) public onlyPauser {
_addPauser(account);
}
function renouncePauser() public {
_removePauser(_msgSender());
}
function _addPauser(address account) internal {
_pausers.add(account);
emit PauserAdded(account);
}
function _removePauser(address account) internal {
_pausers.remove(account);
emit PauserRemoved(account);
}
}
// File: @openzeppelin/contracts/lifecycle/Pausable.sol
pragma solidity ^0.5.0;
/**
* @dev Contract module which allows children to implement an emergency stop
* mechanism that can be triggered by an authorized account.
*
* This module is used through inheritance. It will make available the
* modifiers `whenNotPaused` and `whenPaused`, which can be applied to
* the functions of your contract. Note that they will not be pausable by
* simply including this module, only once the modifiers are put in place.
*/
contract Pausable is Context, PauserRole {
/**
* @dev Emitted when the pause is triggered by a pauser (`account`).
*/
event Paused(address account);
/**
* @dev Emitted when the pause is lifted by a pauser (`account`).
*/
event Unpaused(address account);
bool private _paused;
/**
* @dev Initializes the contract in unpaused state. Assigns the Pauser role
* to the deployer.
*/
constructor () internal {
_paused = false;
}
/**
* @dev Returns true if the contract is paused, and false otherwise.
*/
function paused() public view returns (bool) {
return _paused;
}
/**
* @dev Modifier to make a function callable only when the contract is not paused.
*/
modifier whenNotPaused() {
require(!_paused, "Pausable: paused");
_;
}
/**
* @dev Modifier to make a function callable only when the contract is paused.
*/
modifier whenPaused() {
require(_paused, "Pausable: not paused");
_;
}
/**
* @dev Called by a pauser to pause, triggers stopped state.
*/
function pause() public onlyPauser whenNotPaused {
_paused = true;
emit Paused(_msgSender());
}
/**
* @dev Called by a pauser to unpause, returns to normal state.
*/
function unpause() public onlyPauser whenPaused {
_paused = false;
emit Unpaused(_msgSender());
}
}
// File: @openzeppelin/contracts/utils/ReentrancyGuard.sol
pragma solidity ^0.5.0;
/**
* @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].
*
* _Since v2.5.0:_ this module is now much more gas efficient, given net gas
* metering changes introduced in the Istanbul hardfork.
*/
contract ReentrancyGuard {
bool private _notEntered;
constructor () internal {
// Storing an initial 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 percetange 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.
_notEntered = true;
}
/**
* @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(_notEntered, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_notEntered = false;
_;
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_notEntered = true;
}
}
// File: @openzeppelin/contracts/ownership/Ownable.sol
pragma solidity ^0.5.0;
/**
* @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.
*
* 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(isOwner(), "Ownable: caller is not the owner");
_;
}
/**
* @dev Returns true if the caller is the current owner.
*/
function isOwner() public view returns (bool) {
return _msgSender() == _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 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 onlyOwner {
_transferOwnership(newOwner);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
*/
function _transferOwnership(address newOwner) internal {
require(newOwner != address(0), "Ownable: new owner is the zero address");
emit OwnershipTransferred(_owner, newOwner);
_owner = newOwner;
}
}
// File: contracts/util/Whitelist.sol
pragma solidity 0.5.15;
contract Whitelist is Ownable {
mapping(address => bool) whitelist;
event AddedToWhitelist(address indexed account);
event RemovedFromWhitelist(address indexed account);
function addToWhitelist(address _address) public onlyOwner {
whitelist[_address] = true;
emit AddedToWhitelist(_address);
}
function removefromWhitelist(address _address) public onlyOwner {
whitelist[_address] = false;
emit RemovedFromWhitelist(_address);
}
function isWhitelisted(address _address) public view returns (bool) {
return whitelist[_address];
}
}
// File: contracts/interface/IKyberNetworkProxy.sol
pragma solidity 0.5.15;
contract IKyberNetworkProxy {
function getExpectedRate(ERC20 src, ERC20 dest, uint srcQty) external view returns (uint expectedRate, uint slippageRate);
function swapEtherToToken(ERC20 token, uint minConversionRate) external payable returns(uint);
function swapTokenToEther(ERC20 token, uint tokenQty, uint minRate) external payable returns(uint);
function swapTokenToToken(ERC20 src, uint srcAmount, ERC20 dest, uint minRate) external returns(uint);
}
// File: contracts/interface/IKyberStaking.sol
pragma solidity 0.5.15;
contract IKyberStaking {
function deposit(uint256 amount) external;
function withdraw(uint256 amount) external;
function getLatestStakeBalance(address staker) external view returns(uint);
}
// File: contracts/interface/IKyberDAO.sol
pragma solidity 0.5.15;
contract IKyberDAO {
function vote(uint256 campaignID, uint256 option) external;
}
// File: contracts/interface/IKyberFeeHandler.sol
pragma solidity 0.5.15;
contract IKyberFeeHandler {
function claimStakerReward(
address staker,
uint256 epoch
) external returns(uint256 amountWei);
}
// File: contracts/xKNC.sol
pragma solidity 0.5.15;
/*
* xKNC KyberDAO Pool Token
* Communal Staking Pool with Stated Governance Position
*/
contract xKNC is ERC20, ERC20Detailed, Whitelist, Pausable, ReentrancyGuard {
using SafeMath for uint256;
using SafeERC20 for ERC20;
address private constant ETH_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
ERC20 public knc;
IKyberDAO public kyberDao;
IKyberStaking public kyberStaking;
IKyberNetworkProxy public kyberProxy;
IKyberFeeHandler[] public kyberFeeHandlers;
address[] private kyberFeeTokens;
uint256 constant PERCENT = 100;
uint256 constant MAX_UINT = 2**256 - 1;
uint256 constant INITIAL_SUPPLY_MULTIPLIER = 10;
uint256[] public feeDivisors;
uint256 private withdrawableEthFees;
uint256 private withdrawableKncFees;
string public mandate;
mapping(address => bool) fallbackAllowedAddress;
struct FeeStructure {
uint mintFee;
uint burnFee;
uint claimFee;
}
FeeStructure public feeStructure;
event MintWithEth(
address indexed user,
uint256 ethPayable,
uint256 mintAmount,
uint256 timestamp
);
event MintWithKnc(
address indexed user,
uint256 kncPayable,
uint256 mintAmount,
uint256 timestamp
);
event Burn(
address indexed user,
bool redeemedForKnc,
uint256 burnAmount,
uint256 timestamp
);
event FeeWithdraw(uint256 ethAmount, uint256 kncAmount, uint256 timestamp);
event FeeDivisorsSet(uint256 mintFee, uint256 burnFee, uint256 claimFee);
event EthRewardClaimed(uint256 amount, uint256 timestamp);
event TokenRewardClaimed(uint256 amount, uint256 timestamp);
enum FeeTypes {MINT, BURN, CLAIM}
constructor(
string memory _mandate,
address _kyberStakingAddress,
address _kyberProxyAddress,
address _kyberTokenAddress,
address _kyberDaoAddress
) public ERC20Detailed("xKNC", "xKNCa", 18) {
mandate = _mandate;
kyberStaking = IKyberStaking(_kyberStakingAddress);
kyberProxy = IKyberNetworkProxy(_kyberProxyAddress);
knc = ERC20(_kyberTokenAddress);
kyberDao = IKyberDAO(_kyberDaoAddress);
_addFallbackAllowedAddress(_kyberProxyAddress);
}
/*
* @notice Called by users buying with ETH
* @dev Swaps ETH for KNC, deposits to Staking contract
* @dev: Mints pro rata xKNC tokens
* @param: kyberProxy.getExpectedRate(eth => knc)
*/
function mint(uint256 minRate) external payable whenNotPaused {
require(msg.value > 0, "Must send eth with tx");
// ethBalBefore checked in case of eth still waiting for exch to KNC
uint256 ethBalBefore = getFundEthBalanceWei().sub(msg.value);
uint256 fee = _administerEthFee(FeeTypes.MINT, ethBalBefore);
uint256 ethValueForKnc = msg.value.sub(fee);
uint256 kncBalanceBefore = getFundKncBalanceTwei();
_swapEtherToKnc(ethValueForKnc, minRate);
_deposit(getAvailableKncBalanceTwei());
uint256 mintAmount = _calculateMintAmount(kncBalanceBefore);
emit MintWithEth(msg.sender, msg.value, mintAmount, block.timestamp);
return super._mint(msg.sender, mintAmount);
}
/*
* @notice Called by users buying with KNC
* @notice Users must submit ERC20 approval before calling
* @dev Deposits to Staking contract
* @dev: Mints pro rata xKNC tokens
* @param: Number of KNC to contribue
*/
function mintWithKnc(uint256 kncAmountTwei) external whenNotPaused {
require(kncAmountTwei > 0, "Must contribute KNC");
knc.safeTransferFrom(msg.sender, address(this), kncAmountTwei);
uint256 kncBalanceBefore = getFundKncBalanceTwei();
_administerKncFee(kncAmountTwei, FeeTypes.MINT);
_deposit(getAvailableKncBalanceTwei());
uint256 mintAmount = _calculateMintAmount(kncBalanceBefore);
emit MintWithKnc(msg.sender, kncAmountTwei, mintAmount, block.timestamp);
return super._mint(msg.sender, mintAmount);
}
/*
* @notice Called by users burning their xKNC
* @dev Calculates pro rata KNC and redeems from Staking contract
* @dev: Exchanges for ETH if necessary and pays out to caller
* @param tokensToRedeem
* @param redeemForKnc bool: if true, redeem for KNC; otherwise ETH
* @param kyberProxy.getExpectedRate(knc => eth)
*/
function burn(
uint256 tokensToRedeemTwei,
bool redeemForKnc,
uint256 minRate
) external nonReentrant {
require(
balanceOf(msg.sender) >= tokensToRedeemTwei,
"Insufficient balance"
);
uint256 proRataKnc = getFundKncBalanceTwei().mul(tokensToRedeemTwei).div(
totalSupply()
);
_withdraw(proRataKnc);
super._burn(msg.sender, tokensToRedeemTwei);
if (redeemForKnc) {
uint256 fee = _administerKncFee(proRataKnc, FeeTypes.BURN);
knc.safeTransfer(msg.sender, proRataKnc.sub(fee));
} else {
// safeguard to not overcompensate _burn sender in case eth still awaiting for exch to KNC
uint256 ethBalBefore = getFundEthBalanceWei();
kyberProxy.swapTokenToEther(
knc,
getAvailableKncBalanceTwei(),
minRate
);
_administerEthFee(FeeTypes.BURN, ethBalBefore);
uint256 valToSend = getFundEthBalanceWei().sub(ethBalBefore);
(bool success, ) = msg.sender.call.value(valToSend)("");
require(success, "Burn transfer failed");
}
emit Burn(msg.sender, redeemForKnc, tokensToRedeemTwei, block.timestamp);
}
/*
* @notice Calculates proportional issuance according to KNC contribution
* @notice Fund starts at ratio of INITIAL_SUPPLY_MULTIPLIER/1 == xKNC supply/KNC balance
* and approaches 1/1 as rewards accrue in KNC
* @param kncBalanceBefore used to determine ratio of incremental to current KNC
*/
function _calculateMintAmount(uint256 kncBalanceBefore)
private
view
returns (uint256 mintAmount)
{
uint256 kncBalanceAfter = getFundKncBalanceTwei();
if (totalSupply() == 0)
return kncBalanceAfter.mul(INITIAL_SUPPLY_MULTIPLIER);
mintAmount = (kncBalanceAfter.sub(kncBalanceBefore))
.mul(totalSupply())
.div(kncBalanceBefore);
}
/*
* @notice KyberDAO deposit
*/
function _deposit(uint256 amount) private {
kyberStaking.deposit(amount);
}
/*
* @notice KyberDAO withdraw
*/
function _withdraw(uint256 amount) private {
kyberStaking.withdraw(amount);
}
/*
* @notice Vote on KyberDAO campaigns
* @dev Admin calls with relevant params for each campaign in an epoch
* @param DAO campaign ID
* @param Choice of voting option
*/
function vote(uint256 campaignID, uint256 option) external onlyOwner {
kyberDao.vote(campaignID, option);
}
/*
* @notice Claim reward from previous epoch
* @notice All fee handlers should be called at once
* @dev Admin calls with relevant params
* @dev ETH/other asset rewards swapped into KNC
* @param epoch - KyberDAO epoch
* @param feeHandlerIndices - indices of feeHandler contract to claim from
* @param maxAmountsToSell - sellAmount above which slippage would be too high
* and rewards would redirected into KNC in multiple trades
* @param minRates - kyberProxy.getExpectedRate(eth/token => knc)
*/
function claimReward(
uint256 epoch,
uint256[] calldata feeHandlerIndices,
uint256[] calldata maxAmountsToSell,
uint256[] calldata minRates
) external onlyOwner {
require(
feeHandlerIndices.length == maxAmountsToSell.length,
"Arrays must be equal length"
);
require(
maxAmountsToSell.length == minRates.length,
"Arrays must be equal length"
);
uint256 ethBalBefore = getFundEthBalanceWei();
for (uint256 i = 0; i < feeHandlerIndices.length; i++) {
kyberFeeHandlers[i].claimStakerReward(address(this), epoch);
if (kyberFeeTokens[i] == ETH_ADDRESS) {
emit EthRewardClaimed(
getFundEthBalanceWei().sub(ethBalBefore),
block.timestamp
);
_administerEthFee(FeeTypes.CLAIM, ethBalBefore);
} else {
uint256 tokenBal = IERC20(kyberFeeTokens[i]).balanceOf(
address(this)
);
emit TokenRewardClaimed(tokenBal, block.timestamp);
}
_unwindRewards(
feeHandlerIndices[i],
maxAmountsToSell[i],
minRates[i]
);
}
_deposit(getAvailableKncBalanceTwei());
}
/*
* @notice Called when rewards size is too big for the one trade executed by `claimReward`
* @param feeHandlerIndices - index of feeHandler previously claimed from
* @param maxAmountsToSell - sellAmount above which slippage would be too high
* and rewards would redirected into KNC in multiple trades
* @param minRates - kyberProxy.getExpectedRate(eth/token => knc)
*/
function unwindRewards(
uint256[] calldata feeHandlerIndices,
uint256[] calldata maxAmountsToSell,
uint256[] calldata minRates
) external onlyOwner {
for (uint256 i = 0; i < feeHandlerIndices.length; i++) {
_unwindRewards(
feeHandlerIndices[i],
maxAmountsToSell[i],
minRates[i]
);
}
_deposit(getAvailableKncBalanceTwei());
}
/*
* @notice Exchanges reward tokens (ETH, etc) for KNC
*/
function _unwindRewards(
uint256 feeHandlerIndex,
uint256 maxAmountToSell,
uint256 minRate
) private {
address rewardTokenAddress = kyberFeeTokens[feeHandlerIndex];
uint256 amountToSell;
if (rewardTokenAddress == ETH_ADDRESS) {
uint256 ethBal = getFundEthBalanceWei();
if (maxAmountToSell < ethBal) {
amountToSell = maxAmountToSell;
} else {
amountToSell = ethBal;
}
_swapEtherToKnc(amountToSell, minRate);
} else {
uint256 tokenBal = IERC20(rewardTokenAddress).balanceOf(
address(this)
);
if (maxAmountToSell < tokenBal) {
amountToSell = maxAmountToSell;
} else {
amountToSell = tokenBal;
}
uint256 kncBalanceBefore = getAvailableKncBalanceTwei();
_swapTokenToKnc(
rewardTokenAddress,
amountToSell,
minRate
);
uint256 kncBalanceAfter = getAvailableKncBalanceTwei();
_administerKncFee(
kncBalanceAfter.sub(kncBalanceBefore),
FeeTypes.CLAIM
);
}
}
function _swapEtherToKnc(
uint256 amount,
uint256 minRate
) private {
kyberProxy.swapEtherToToken.value(amount)(knc, minRate);
}
function _swapTokenToKnc(
address fromAddress,
uint256 amount,
uint256 minRate
) private {
kyberProxy.swapTokenToToken(
ERC20(fromAddress),
amount,
knc,
minRate
);
}
/*
* @notice Returns ETH balance belonging to the fund
*/
function getFundEthBalanceWei() public view returns (uint256) {
return address(this).balance.sub(withdrawableEthFees);
}
/*
* @notice Returns KNC balance staked to DAO
*/
function getFundKncBalanceTwei() public view returns (uint256) {
return kyberStaking.getLatestStakeBalance(address(this));
}
/*
* @notice Returns KNC balance available to stake
*/
function getAvailableKncBalanceTwei() public view returns (uint256) {
return knc.balanceOf(address(this)).sub(withdrawableKncFees);
}
function _administerEthFee(FeeTypes _type, uint256 ethBalBefore)
private
returns (uint256 fee)
{
if (!isWhitelisted(msg.sender)) {
uint256 feeRate = getFeeRate(_type);
if (feeRate == 0) return 0;
fee = (getFundEthBalanceWei().sub(ethBalBefore)).div(feeRate);
withdrawableEthFees = withdrawableEthFees.add(fee);
}
}
function _administerKncFee(uint256 _kncAmount, FeeTypes _type)
private
returns (uint256 fee)
{
if (!isWhitelisted(msg.sender)) {
uint256 feeRate = getFeeRate(_type);
if (feeRate == 0) return 0;
fee = _kncAmount.div(feeRate);
withdrawableKncFees = withdrawableKncFees.add(fee);
}
}
function getFeeRate(FeeTypes _type) public view returns (uint256) {
if (_type == FeeTypes.MINT) return feeStructure.mintFee;
if (_type == FeeTypes.BURN) return feeStructure.burnFee;
if (_type == FeeTypes.CLAIM) return feeStructure.claimFee;
}
/*
* @notice Called on initial deployment and on the addition of new fee handlers
* @param Address of KyberFeeHandler contract
* @param Address of underlying rewards token
*/
function addKyberFeeHandler(
address _kyberfeeHandlerAddress,
address _tokenAddress
) external onlyOwner {
kyberFeeHandlers.push(IKyberFeeHandler(_kyberfeeHandlerAddress));
kyberFeeTokens.push(_tokenAddress);
if (_tokenAddress != ETH_ADDRESS) {
_approveKyberProxyContract(_tokenAddress, false);
} else {
_addFallbackAllowedAddress(_kyberfeeHandlerAddress);
}
}
/* UTILS */
/*
* @notice Called by admin on deployment
* @dev Approves Kyber Staking contract to deposit KNC
* @param Pass _reset as true if resetting allowance to zero
*/
function approveStakingContract(bool _reset) external onlyOwner {
uint256 amount = _reset ? 0 : MAX_UINT;
knc.approve(address(kyberStaking), amount);
}
/*
* @notice Called by admin on deployment for KNC
* @dev Approves Kyber Proxy contract to trade KNC
* @param Token to approve on proxy contract
* @param Pass _reset as true if resetting allowance to zero
*/
function approveKyberProxyContract(address _token, bool _reset)
external
onlyOwner
{
_approveKyberProxyContract(_token, _reset);
}
function _approveKyberProxyContract(address _token, bool _reset) private {
uint256 amount = _reset ? 0 : MAX_UINT;
IERC20(_token).approve(address(kyberProxy), amount);
}
/*
* @notice Called by admin on deployment
* @dev (1 / feeDivisor) = % fee on mint, burn, ETH claims
* @dev ex: A feeDivisor of 334 suggests a fee of 0.3%
* @param feeDivisors[mint, burn, claim]:
*/
function setFeeDivisors(uint256 _mintFee, uint256 _burnFee, uint256 _claimFee)
external
onlyOwner
{
require(
_mintFee >= 100 || _mintFee == 0,
"Mint fee must be zero or equal to or less than 1%"
);
require(
_burnFee >= 100,
"Burn fee must be equal to or less than 1%"
);
require(_claimFee >= 10, "Claim fee must be less than 10%");
feeStructure.mintFee = _mintFee;
feeStructure.burnFee = _burnFee;
feeStructure.claimFee = _claimFee;
emit FeeDivisorsSet(_mintFee, _burnFee, _claimFee);
}
function withdrawFees() external onlyOwner {
uint256 ethFees = withdrawableEthFees;
uint256 kncFees = withdrawableKncFees;
withdrawableEthFees = 0;
withdrawableKncFees = 0;
(bool success, ) = msg.sender.call.value(ethFees)("");
require(success, "Burn transfer failed");
knc.safeTransfer(owner(), kncFees);
emit FeeWithdraw(ethFees, kncFees, block.timestamp);
}
function addFallbackAllowedAddress(address _address) external onlyOwner {
_addFallbackAllowedAddress(_address);
}
function _addFallbackAllowedAddress(address _address) private {
fallbackAllowedAddress[_address] = true;
}
/*
* @notice Fallback to accommodate claimRewards function
*/
function() external payable {
require(
fallbackAllowedAddress[msg.sender],
"Only approved address can use fallback"
);
}
}