文件 1 的 1:AllowanceProxy.sol
pragma solidity ^0.6.0;
pragma experimental ABIEncoderV2;
interface ERC20 {
function totalSupply() external view returns (uint256 supply);
function balanceOf(address _owner) external view returns (uint256 balance);
function transfer(address _to, uint256 _value) external returns (bool success);
function transferFrom(address _from, address _to, uint256 _value)
external
returns (bool success);
function approve(address _spender, uint256 _value) external returns (bool success);
function allowance(address _owner, address _spender) external view returns (uint256 remaining);
function decimals() external view returns (uint256 digits);
event Approval(address indexed _owner, address indexed _spender, uint256 _value);
} library Address {
function isContract(address account) internal view returns (bool) {
bytes32 codehash;
bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
assembly { codehash := extcodehash(account) }
return (codehash != accountHash && codehash != 0x0);
}
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
(bool success, ) = recipient.call{ value: amount }("");
require(success, "Address: unable to send value, recipient may have reverted");
}
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
return _functionCallWithValue(target, data, 0, errorMessage);
}
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");
}
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");
(bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
if (success) {
return returndata;
} else {
if (returndata.length > 0) {
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
} library SafeMath {
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, "SafeMath: addition overflow");
return c;
}
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return sub(a, b, "SafeMath: subtraction overflow");
}
function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b <= a, errorMessage);
uint256 c = a - b;
return c;
}
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}
function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b > 0, errorMessage);
uint256 c = a / b;
return c;
}
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return mod(a, b, "SafeMath: modulo by zero");
}
function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
} library SafeERC20 {
using SafeMath for uint256;
using Address for address;
function safeTransfer(ERC20 token, address to, uint256 value) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
}
function safeTransferFrom(ERC20 token, address from, address to, uint256 value) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
}
function safeApprove(ERC20 token, address spender, uint256 value) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, 0));
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
}
function safeIncreaseAllowance(ERC20 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(ERC20 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));
}
function _callOptionalReturn(ERC20 token, bytes memory data) private {
bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
if (returndata.length > 0) {
require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
}
}
} contract AdminAuth {
using SafeERC20 for ERC20;
address public owner;
address public admin;
modifier onlyOwner() {
require(owner == msg.sender);
_;
}
modifier onlyAdmin() {
require(admin == msg.sender);
_;
}
constructor() public {
owner = 0xBc841B0dE0b93205e912CFBBd1D0c160A1ec6F00;
admin = 0x25eFA336886C74eA8E282ac466BdCd0199f85BB9;
}
function setAdminByOwner(address _admin) public {
require(msg.sender == owner);
require(admin == address(0));
admin = _admin;
}
function setAdminByAdmin(address _admin) public {
require(msg.sender == admin);
admin = _admin;
}
function setOwnerByAdmin(address _owner) public {
require(msg.sender == admin);
owner = _owner;
}
function kill() public onlyOwner {
selfdestruct(payable(owner));
}
function withdrawStuckFunds(address _token, uint _amount) public onlyOwner {
if (_token == 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE) {
payable(owner).transfer(_amount);
} else {
ERC20(_token).safeTransfer(owner, _amount);
}
}
} abstract contract GasTokenInterface is ERC20 {
function free(uint256 value) public virtual returns (bool success);
function freeUpTo(uint256 value) public virtual returns (uint256 freed);
function freeFrom(address from, uint256 value) public virtual returns (bool success);
function freeFromUpTo(address from, uint256 value) public virtual returns (uint256 freed);
} contract DSMath {
function add(uint256 x, uint256 y) internal pure returns (uint256 z) {
require((z = x + y) >= x);
}
function sub(uint256 x, uint256 y) internal pure returns (uint256 z) {
require((z = x - y) <= x);
}
function mul(uint256 x, uint256 y) internal pure returns (uint256 z) {
require(y == 0 || (z = x * y) / y == x);
}
function div(uint256 x, uint256 y) internal pure returns (uint256 z) {
return x / y;
}
function min(uint256 x, uint256 y) internal pure returns (uint256 z) {
return x <= y ? x : y;
}
function max(uint256 x, uint256 y) internal pure returns (uint256 z) {
return x >= y ? x : y;
}
function imin(int256 x, int256 y) internal pure returns (int256 z) {
return x <= y ? x : y;
}
function imax(int256 x, int256 y) internal pure returns (int256 z) {
return x >= y ? x : y;
}
uint256 constant WAD = 10**18;
uint256 constant RAY = 10**27;
function wmul(uint256 x, uint256 y) internal pure returns (uint256 z) {
z = add(mul(x, y), WAD / 2) / WAD;
}
function rmul(uint256 x, uint256 y) internal pure returns (uint256 z) {
z = add(mul(x, y), RAY / 2) / RAY;
}
function wdiv(uint256 x, uint256 y) internal pure returns (uint256 z) {
z = add(mul(x, WAD), y / 2) / y;
}
function rdiv(uint256 x, uint256 y) internal pure returns (uint256 z) {
z = add(mul(x, RAY), y / 2) / y;
}
function rpow(uint256 x, uint256 n) internal pure returns (uint256 z) {
z = n % 2 != 0 ? x : RAY;
for (n /= 2; n != 0; n /= 2) {
x = rmul(x, x);
if (n % 2 != 0) {
z = rmul(z, x);
}
}
}
} abstract contract TokenInterface {
address public constant WETH_ADDRESS = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
function allowance(address, address) public virtual returns (uint256);
function balanceOf(address) public virtual returns (uint256);
function approve(address, uint256) public virtual;
function transfer(address, uint256) public virtual returns (bool);
function transferFrom(address, address, uint256) public virtual returns (bool);
function deposit() public virtual payable;
function withdraw(uint256) public virtual;
} interface ExchangeInterfaceV3 {
function sell(address _srcAddr, address _destAddr, uint _srcAmount, bytes memory _additionalData) external payable returns (uint);
function buy(address _srcAddr, address _destAddr, uint _destAmount, bytes memory _additionalData) external payable returns(uint);
function getSellRate(address _srcAddr, address _destAddr, uint _srcAmount, bytes memory _additionalData) external view returns (uint);
function getBuyRate(address _srcAddr, address _destAddr, uint _srcAmount, bytes memory _additionalData) external view returns (uint);
} contract ZrxAllowlist is AdminAuth {
mapping (address => bool) public zrxAllowlist;
mapping(address => bool) private nonPayableAddrs;
constructor() public {
zrxAllowlist[0x6958F5e95332D93D21af0D7B9Ca85B8212fEE0A5] = true;
zrxAllowlist[0x61935CbDd02287B511119DDb11Aeb42F1593b7Ef] = true;
zrxAllowlist[0xDef1C0ded9bec7F1a1670819833240f027b25EfF] = true;
zrxAllowlist[0x080bf510FCbF18b91105470639e9561022937712] = true;
nonPayableAddrs[0x080bf510FCbF18b91105470639e9561022937712] = true;
}
function setAllowlistAddr(address _zrxAddr, bool _state) public onlyOwner {
zrxAllowlist[_zrxAddr] = _state;
}
function isZrxAddr(address _zrxAddr) public view returns (bool) {
return zrxAllowlist[_zrxAddr];
}
function addNonPayableAddr(address _nonPayableAddr) public onlyOwner {
nonPayableAddrs[_nonPayableAddr] = true;
}
function removeNonPayableAddr(address _nonPayableAddr) public onlyOwner {
nonPayableAddrs[_nonPayableAddr] = false;
}
function isNonPayableAddr(address _addr) public view returns(bool) {
return nonPayableAddrs[_addr];
}
}
contract DFSExchangeData {
enum ExchangeType { _, OASIS, KYBER, UNISWAP, ZEROX }
enum ActionType { SELL, BUY }
struct OffchainData {
address wrapper;
address exchangeAddr;
address allowanceTarget;
uint256 price;
uint256 protocolFee;
bytes callData;
}
struct ExchangeData {
address srcAddr;
address destAddr;
uint256 srcAmount;
uint256 destAmount;
uint256 minPrice;
uint256 dfsFeeDivider;
address user;
address wrapper;
bytes wrapperData;
OffchainData offchainData;
}
function packExchangeData(ExchangeData memory _exData) public pure returns(bytes memory) {
return abi.encode(_exData);
}
function unpackExchangeData(bytes memory _data) public pure returns(ExchangeData memory _exData) {
_exData = abi.decode(_data, (ExchangeData));
}
} contract Discount {
address public owner;
mapping(address => CustomServiceFee) public serviceFees;
uint256 constant MAX_SERVICE_FEE = 400;
struct CustomServiceFee {
bool active;
uint256 amount;
}
constructor() public {
owner = msg.sender;
}
function isCustomFeeSet(address _user) public view returns (bool) {
return serviceFees[_user].active;
}
function getCustomServiceFee(address _user) public view returns (uint256) {
return serviceFees[_user].amount;
}
function setServiceFee(address _user, uint256 _fee) public {
require(msg.sender == owner, "Only owner");
require(_fee >= MAX_SERVICE_FEE || _fee == 0);
serviceFees[_user] = CustomServiceFee({active: true, amount: _fee});
}
function disableServiceFee(address _user) public {
require(msg.sender == owner, "Only owner");
serviceFees[_user] = CustomServiceFee({active: false, amount: 0});
}
}
abstract contract IFeeRecipient {
function getFeeAddr() public view virtual returns (address);
function changeWalletAddr(address _newWallet) public virtual;
} contract DFSExchangeHelper {
string public constant ERR_OFFCHAIN_DATA_INVALID = "Offchain data invalid";
using SafeERC20 for ERC20;
address public constant KYBER_ETH_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
address public constant EXCHANGE_WETH_ADDRESS = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
IFeeRecipient public constant _feeRecipient = IFeeRecipient(0x39C4a92Dc506300c3Ea4c67ca4CA611102ee6F2A);
address public constant DISCOUNT_ADDRESS = 0x1b14E8D511c9A4395425314f849bD737BAF8208F;
address public constant SAVER_EXCHANGE_REGISTRY = 0x25dd3F51e0C3c3Ff164DDC02A8E4D65Bb9cBB12D;
address public constant ZRX_ALLOWLIST_ADDR = 0x4BA1f38427b33B8ab7Bb0490200dAE1F1C36823F;
function getDecimals(address _token) internal view returns (uint256) {
if (_token == KYBER_ETH_ADDRESS) return 18;
return ERC20(_token).decimals();
}
function getBalance(address _tokenAddr) internal view returns (uint balance) {
if (_tokenAddr == KYBER_ETH_ADDRESS) {
balance = address(this).balance;
} else {
balance = ERC20(_tokenAddr).balanceOf(address(this));
}
}
function sendLeftover(address _srcAddr, address _destAddr, address payable _to) internal {
if (address(this).balance > 0) {
_to.transfer(address(this).balance);
}
if (getBalance(_srcAddr) > 0) {
ERC20(_srcAddr).safeTransfer(_to, getBalance(_srcAddr));
}
if (getBalance(_destAddr) > 0) {
ERC20(_destAddr).safeTransfer(_to, getBalance(_destAddr));
}
}
function getFee(uint256 _amount, address _user, address _token, uint256 _dfsFeeDivider) internal returns (uint256 feeAmount) {
if (_dfsFeeDivider != 0 && Discount(DISCOUNT_ADDRESS).isCustomFeeSet(_user)) {
_dfsFeeDivider = Discount(DISCOUNT_ADDRESS).getCustomServiceFee(_user);
}
if (_dfsFeeDivider == 0) {
feeAmount = 0;
} else {
feeAmount = _amount / _dfsFeeDivider;
if (feeAmount > (_amount / 10)) {
feeAmount = _amount / 10;
}
address walletAddr = _feeRecipient.getFeeAddr();
if (_token == KYBER_ETH_ADDRESS) {
payable(walletAddr).transfer(feeAmount);
} else {
ERC20(_token).safeTransfer(walletAddr, feeAmount);
}
}
}
function sliceUint(bytes memory bs, uint256 start) internal pure returns (uint256) {
require(bs.length >= start + 32, "slicing out of range");
uint256 x;
assembly {
x := mload(add(bs, add(0x20, start)))
}
return x;
}
function writeUint256(bytes memory _b, uint256 _index, uint _input) internal pure {
if (_b.length < _index + 32) {
revert(ERR_OFFCHAIN_DATA_INVALID);
}
bytes32 input = bytes32(_input);
_index += 32;
assembly {
mstore(add(_b, _index), input)
}
}
function ethToWethAddr(address _src) internal pure returns (address) {
return _src == KYBER_ETH_ADDRESS ? EXCHANGE_WETH_ADDRESS : _src;
}
} contract SaverExchangeRegistry is AdminAuth {
mapping(address => bool) private wrappers;
constructor() public {
wrappers[0x880A845A85F843a5c67DB2061623c6Fc3bB4c511] = true;
wrappers[0x4c9B55f2083629A1F7aDa257ae984E03096eCD25] = true;
wrappers[0x42A9237b872368E1bec4Ca8D26A928D7d39d338C] = true;
}
function addWrapper(address _wrapper) public onlyOwner {
wrappers[_wrapper] = true;
}
function removeWrapper(address _wrapper) public onlyOwner {
wrappers[_wrapper] = false;
}
function isWrapper(address _wrapper) public view returns(bool) {
return wrappers[_wrapper];
}
}
abstract contract OffchainWrapperInterface is DFSExchangeData {
function takeOrder(
ExchangeData memory _exData,
ActionType _type
) virtual public payable returns (bool success, uint256);
}
contract DFSExchangeCore is DFSExchangeHelper, DSMath, DFSExchangeData {
string public constant ERR_SLIPPAGE_HIT = "Slippage hit";
string public constant ERR_DEST_AMOUNT_MISSING = "Dest amount missing";
string public constant ERR_WRAPPER_INVALID = "Wrapper invalid";
string public constant ERR_NOT_ZEROX_EXCHANGE = "Zerox exchange invalid";
function _sell(ExchangeData memory exData) internal returns (address, uint) {
address wrapper;
uint swapedTokens;
bool success;
if (exData.srcAddr == KYBER_ETH_ADDRESS) {
exData.srcAddr = ethToWethAddr(exData.srcAddr);
TokenInterface(EXCHANGE_WETH_ADDRESS).deposit{value: exData.srcAmount}();
}
exData.srcAmount -= getFee(exData.srcAmount, exData.user, exData.srcAddr, exData.dfsFeeDivider);
if (exData.offchainData.price > 0) {
(success, swapedTokens) = takeOrder(exData, ActionType.SELL);
if (success) {
wrapper = exData.offchainData.exchangeAddr;
}
}
if (!success) {
swapedTokens = saverSwap(exData, ActionType.SELL);
wrapper = exData.wrapper;
}
if (getBalance(EXCHANGE_WETH_ADDRESS) > 0) {
TokenInterface(EXCHANGE_WETH_ADDRESS).withdraw(
TokenInterface(EXCHANGE_WETH_ADDRESS).balanceOf(address(this))
);
}
if (exData.destAddr == EXCHANGE_WETH_ADDRESS) {
require(getBalance(KYBER_ETH_ADDRESS) >= wmul(exData.minPrice, exData.srcAmount), ERR_SLIPPAGE_HIT);
} else {
require(getBalance(exData.destAddr) >= wmul(exData.minPrice, exData.srcAmount), ERR_SLIPPAGE_HIT);
}
return (wrapper, swapedTokens);
}
function _buy(ExchangeData memory exData) internal returns (address, uint) {
address wrapper;
uint swapedTokens;
bool success;
require(exData.destAmount != 0, ERR_DEST_AMOUNT_MISSING);
exData.srcAmount -= getFee(exData.srcAmount, exData.user, exData.srcAddr, exData.dfsFeeDivider);
if (exData.srcAddr == KYBER_ETH_ADDRESS) {
exData.srcAddr = ethToWethAddr(exData.srcAddr);
TokenInterface(EXCHANGE_WETH_ADDRESS).deposit{value: exData.srcAmount}();
}
if (exData.offchainData.price > 0) {
(success, swapedTokens) = takeOrder(exData, ActionType.BUY);
if (success) {
wrapper = exData.offchainData.exchangeAddr;
}
}
if (!success) {
swapedTokens = saverSwap(exData, ActionType.BUY);
wrapper = exData.wrapper;
}
if (getBalance(EXCHANGE_WETH_ADDRESS) > 0) {
TokenInterface(EXCHANGE_WETH_ADDRESS).withdraw(
TokenInterface(EXCHANGE_WETH_ADDRESS).balanceOf(address(this))
);
}
if (exData.destAddr == EXCHANGE_WETH_ADDRESS) {
require(getBalance(KYBER_ETH_ADDRESS) >= exData.destAmount, ERR_SLIPPAGE_HIT);
} else {
require(getBalance(exData.destAddr) >= exData.destAmount, ERR_SLIPPAGE_HIT);
}
return (wrapper, getBalance(exData.destAddr));
}
function takeOrder(
ExchangeData memory _exData,
ActionType _type
) private returns (bool success, uint256) {
if (!ZrxAllowlist(ZRX_ALLOWLIST_ADDR).isZrxAddr(_exData.offchainData.exchangeAddr)) {
return (false, 0);
}
if (!SaverExchangeRegistry(SAVER_EXCHANGE_REGISTRY).isWrapper(_exData.offchainData.wrapper)) {
return (false, 0);
}
ERC20(_exData.srcAddr).safeTransfer(_exData.offchainData.wrapper, _exData.srcAmount);
return OffchainWrapperInterface(_exData.offchainData.wrapper).takeOrder{value: _exData.offchainData.protocolFee}(_exData, _type);
}
function saverSwap(ExchangeData memory _exData, ActionType _type) internal returns (uint swapedTokens) {
require(SaverExchangeRegistry(SAVER_EXCHANGE_REGISTRY).isWrapper(_exData.wrapper), ERR_WRAPPER_INVALID);
ERC20(_exData.srcAddr).safeTransfer(_exData.wrapper, _exData.srcAmount);
if (_type == ActionType.SELL) {
swapedTokens = ExchangeInterfaceV3(_exData.wrapper).
sell(_exData.srcAddr, _exData.destAddr, _exData.srcAmount, _exData.wrapperData);
} else {
swapedTokens = ExchangeInterfaceV3(_exData.wrapper).
buy(_exData.srcAddr, _exData.destAddr, _exData.destAmount, _exData.wrapperData);
}
}
receive() external virtual payable {}
} contract DefisaverLogger {
event LogEvent(
address indexed contractAddress,
address indexed caller,
string indexed logName,
bytes data
);
function Log(address _contract, address _caller, string memory _logName, bytes memory _data)
public
{
emit LogEvent(_contract, _caller, _logName, _data);
}
} contract GasBurner {
GasTokenInterface public constant gasToken = GasTokenInterface(0x0000000000b3F879cb30FE243b4Dfee438691c04);
modifier burnGas(uint _amount) {
if (gasToken.balanceOf(address(this)) >= _amount) {
gasToken.free(_amount);
}
_;
}
}
contract DFSExchange is DFSExchangeCore, AdminAuth, GasBurner {
using SafeERC20 for ERC20;
uint256 public constant SERVICE_FEE = 800;
DefisaverLogger public constant logger = DefisaverLogger(0x5c55B921f590a89C1Ebe84dF170E655a82b62126);
uint public burnAmount = 10;
function sell(ExchangeData memory exData, address payable _user) public payable burnGas(burnAmount) {
exData.dfsFeeDivider = SERVICE_FEE;
exData.user = _user;
(address wrapper, uint destAmount) = _sell(exData);
sendLeftover(exData.srcAddr, exData.destAddr, _user);
logger.Log(address(this), msg.sender, "ExchangeSell", abi.encode(wrapper, exData.srcAddr, exData.destAddr, exData.srcAmount, destAmount));
}
function buy(ExchangeData memory exData, address payable _user) public payable burnGas(burnAmount){
exData.dfsFeeDivider = SERVICE_FEE;
exData.user = _user;
(address wrapper, uint srcAmount) = _buy(exData);
sendLeftover(exData.srcAddr, exData.destAddr, _user);
logger.Log(address(this), msg.sender, "ExchangeBuy", abi.encode(wrapper, exData.srcAddr, exData.destAddr, srcAmount, exData.destAmount));
}
function changeBurnAmount(uint _newBurnAmount) public {
require(owner == msg.sender);
burnAmount = _newBurnAmount;
}
}
contract AllowanceProxy is AdminAuth {
using SafeERC20 for ERC20;
address public constant KYBER_ETH_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
DFSExchange dfsExchange = DFSExchange(0xc2Ce04e2FB4DD20964b4410FcE718b95963a1587);
function callSell(DFSExchangeCore.ExchangeData memory exData) public payable {
pullAndSendTokens(exData.srcAddr, exData.srcAmount);
dfsExchange.sell{value: msg.value}(exData, msg.sender);
}
function callBuy(DFSExchangeCore.ExchangeData memory exData) public payable {
pullAndSendTokens(exData.srcAddr, exData.srcAmount);
dfsExchange.buy{value: msg.value}(exData, msg.sender);
}
function pullAndSendTokens(address _tokenAddr, uint _amount) internal {
if (_tokenAddr == KYBER_ETH_ADDRESS) {
require(msg.value >= _amount, "msg.value smaller than amount");
} else {
ERC20(_tokenAddr).safeTransferFrom(msg.sender, address(dfsExchange), _amount);
}
}
function ownerChangeExchange(address payable _newExchange) public onlyOwner {
dfsExchange = DFSExchange(_newExchange);
}
}