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mev-briber/contracts/MEVBriber.sol
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//SPDX-License-Identifier: MIT | |
pragma solidity ^0.7.3; | |
pragma experimental ABIEncoderV2; | |
import "./FlashbotsCheckAndSend.sol"; | |
import "./interface/IWETH.sol"; | |
import "@openzeppelin/contracts/utils/Counters.sol"; | |
import "@openzeppelin/contracts/cryptography/ECDSA.sol"; | |
import "@openzeppelin/contracts/drafts/EIP712.sol"; | |
/* | |
Copyright 2021 Kendrick Tan (kendricktrh@gmail.com). | |
This contract is an extension of flashbot's FlashbotsCheckAndSend.sol | |
This contract takes in WETH instead of ETH so that transactions can be signed via a browser. | |
But needs to be approved beforehand. | |
*/ | |
contract MEVBriber is FlashbotsCheckAndSend, EIP712 { | |
using Counters for Counters.Counter; | |
constructor() EIP712("MEVBriber", "1") {} | |
IWETH public constant WETH = | |
IWETH(0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2); | |
event Bribed(address indexed briber, address indexed miner, uint256 amount); | |
bytes32 public constant PERMIT_TYPEHASH = | |
keccak256( | |
"Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)" | |
); | |
mapping(address => Counters.Counter) private _nonces; | |
receive() external payable {} | |
function check32BytesAndSendWETH( | |
address _owner, | |
address _spender, | |
uint256 _value, | |
uint256 _deadline, | |
uint8 _v, | |
bytes32 _r, | |
bytes32 _s, | |
address _target, | |
bytes memory _payload, | |
bytes32 _resultMatch | |
) external { | |
briberPermitted(_owner, _spender, _value, _deadline, _v, _r, _s); | |
_check32Bytes(_target, _payload, _resultMatch); | |
WETH.transferFrom(_owner, address(this), _value); | |
WETH.withdraw(_value); | |
block.coinbase.transfer(_value); | |
emit Bribed(_owner, block.coinbase, _value); | |
} | |
function check32BytesAndSendMultiWETH( | |
address _owner, | |
address _spender, | |
uint256 _value, | |
uint256 _deadline, | |
uint8 _v, | |
bytes32 _r, | |
bytes32 _s, | |
address[] memory _targets, | |
bytes[] memory _payloads, | |
bytes32[] memory _resultMatches | |
) external { | |
require(_targets.length == _payloads.length); | |
require(_targets.length == _resultMatches.length); | |
briberPermitted(_owner, _spender, _value, _deadline, _v, _r, _s); | |
for (uint256 i = 0; i < _targets.length; i++) { | |
_check32Bytes(_targets[i], _payloads[i], _resultMatches[i]); | |
} | |
WETH.transferFrom(_owner, address(this), _value); | |
WETH.withdraw(_value); | |
block.coinbase.transfer(_value); | |
emit Bribed(_owner, block.coinbase, _value); | |
} | |
function checkBytesAndSendWETH( | |
address _owner, | |
address _spender, | |
uint256 _value, | |
uint256 _deadline, | |
uint8 _v, | |
bytes32 _r, | |
bytes32 _s, | |
address _target, | |
bytes memory _payload, | |
bytes memory _resultMatch | |
) external { | |
briberPermitted(_owner, _spender, _value, _deadline, _v, _r, _s); | |
_checkBytes(_target, _payload, _resultMatch); | |
WETH.transferFrom(_owner, address(this), _value); | |
WETH.withdraw(_value); | |
block.coinbase.transfer(_value); | |
emit Bribed(_owner, block.coinbase, _value); | |
} | |
function checkBytesAndSendMultiWETH( | |
address _owner, | |
address _spender, | |
uint256 _value, | |
uint256 _deadline, | |
uint8 _v, | |
bytes32 _r, | |
bytes32 _s, | |
address[] memory _targets, | |
bytes[] memory _payloads, | |
bytes[] memory _resultMatches | |
) external { | |
require(_targets.length == _payloads.length); | |
require(_targets.length == _resultMatches.length); | |
briberPermitted(_owner, _spender, _value, _deadline, _v, _r, _s); | |
for (uint256 i = 0; i < _targets.length; i++) { | |
_checkBytes(_targets[i], _payloads[i], _resultMatches[i]); | |
} | |
WETH.transferFrom(_owner, address(this), _value); | |
WETH.withdraw(_value); | |
block.coinbase.transfer(_value); | |
emit Bribed(_owner, block.coinbase, _value); | |
} | |
// Briber permit functionality | |
function briberPermitted( | |
address owner, | |
address spender, | |
uint256 value, | |
uint256 deadline, | |
uint8 v, | |
bytes32 r, | |
bytes32 s | |
) public { | |
// solhint-disable-next-line not-rely-on-time | |
require(block.timestamp <= deadline, "ERC20Permit: expired deadline"); | |
bytes32 structHash = | |
keccak256( | |
abi.encode( | |
PERMIT_TYPEHASH, | |
owner, | |
spender, | |
value, | |
_nonces[owner].current(), | |
deadline | |
) | |
); | |
bytes32 hash = _hashTypedDataV4(structHash); | |
address signer = ECDSA.recover(hash, v, r, s); | |
require(signer == owner, "ERC20Permit: invalid signature"); | |
require(spender == address(this), "ERC20Permit: invalid signature"); | |
_nonces[owner].increment(); | |
} | |
// **** Helpers **** | |
function nonces(address owner) public view virtual returns (uint256) { | |
return _nonces[owner].current(); | |
} | |
} |