// SPDX-License-Identifier: MITpragmasolidity >=0.6.0 <0.8.0;/*
* @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.
*/abstractcontractContext{
function_msgSender() internalviewvirtualreturns (addresspayable) {
returnmsg.sender;
}
function_msgData() internalviewvirtualreturns (bytesmemory) {
this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691returnmsg.data;
}
}
Contract Source Code
File 2 of 6: FeeReceiverMultichain.sol
pragmasolidity =0.6.6;import"@openzeppelin/contracts/token/ERC20/IERC20.sol";
import"@openzeppelin/contracts/access/Ownable.sol";
import"./libraries/TransferHelper.sol";
import"./interfaces/IWETH.sol";
contractFeeReceiverMultichainisOwnable{
addresspublic WETH;
constructor(address _WETH) public{
WETH = _WETH;
}
/// @dev converts WETH to ETHfunctionunwrapWETH() public{
uint256 balance = IWETH(WETH).balanceOf(address(this));
require(balance >0, "FeeReceiver: Nothing to unwrap");
IWETH(WETH).withdraw(balance);
}
/// @dev lets the owner withdraw ETH from the contractfunctionwithdrawETH(addresspayable to, uint256 amount) externalonlyOwner{
to.transfer(amount);
}
/// @dev lets the owner withdraw any ERC20 Token from the contractfunctionwithdrawERC20Token(address token,
address to,
uint256 amount
) externalonlyOwner{
IERC20(token).transfer(to, amount);
}
/// @dev allows to receive ETH on this contractreceive() externalpayable{}
}
Contract Source Code
File 3 of 6: IERC20.sol
// SPDX-License-Identifier: MITpragmasolidity >=0.6.0 <0.8.0;/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/interfaceIERC20{
/**
* @dev Returns the amount of tokens in existence.
*/functiontotalSupply() externalviewreturns (uint256);
/**
* @dev Returns the amount of tokens owned by `account`.
*/functionbalanceOf(address account) externalviewreturns (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.
*/functiontransfer(address recipient, uint256 amount) externalreturns (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.
*/functionallowance(address owner, address spender) externalviewreturns (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.
*/functionapprove(address spender, uint256 amount) externalreturns (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.
*/functiontransferFrom(address sender, address recipient, uint256 amount) externalreturns (bool);
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/eventTransfer(addressindexedfrom, addressindexed 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.
*/eventApproval(addressindexed owner, addressindexed spender, uint256 value);
}
// SPDX-License-Identifier: MITpragmasolidity >=0.6.0 <0.8.0;import"../utils/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.
*/abstractcontractOwnableisContext{
addressprivate _owner;
eventOwnershipTransferred(addressindexed previousOwner, addressindexed 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.
*/functionowner() publicviewvirtualreturns (address) {
return _owner;
}
/**
* @dev Throws if called by any account other than the owner.
*/modifieronlyOwner() {
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.
*/functionrenounceOwnership() publicvirtualonlyOwner{
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.
*/functiontransferOwnership(address newOwner) publicvirtualonlyOwner{
require(newOwner !=address(0), "Ownable: new owner is the zero address");
emit OwnershipTransferred(_owner, newOwner);
_owner = newOwner;
}
}
Contract Source Code
File 6 of 6: TransferHelper.sol
pragmasolidity =0.6.6;// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/falselibraryTransferHelper{
functionsafeApprove(address token,
address to,
uint256 value
) internal{
// bytes4(keccak256(bytes('approve(address,uint256)')));
(bool success, bytesmemory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
require(success && (data.length==0||abi.decode(data, (bool))), "TransferHelper: APPROVE_FAILED");
}
functionsafeTransfer(address token,
address to,
uint256 value
) internal{
// bytes4(keccak256(bytes('transfer(address,uint256)')));
(bool success, bytesmemory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
require(success && (data.length==0||abi.decode(data, (bool))), "TransferHelper: TRANSFER_FAILED");
}
functionsafeTransferFrom(address token,
addressfrom,
address to,
uint256 value
) internal{
// bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
(bool success, bytesmemory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
require(success && (data.length==0||abi.decode(data, (bool))), "TransferHelper: TRANSFER_FROM_FAILED");
}
functionsafeTransferETH(address to, uint256 value) internal{
(bool success, ) = to.call{value: value}(newbytes(0));
require(success, "TransferHelper: ETH_TRANSFER_FAILED");
}
}