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May 29, 2021 16:16
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| pragma solidity ^0.5.16; | |
| interface IERC20 { | |
| function balanceOf(address _owner) external view returns (uint256 balance); | |
| function transfer(address _to, uint256 _value) external returns (bool success); | |
| } | |
| interface IFlashloanReceiver { | |
| function executeOperation( | |
| address sender, | |
| address underlying, | |
| uint amount, | |
| uint fee, | |
| bytes calldata params | |
| ) external payable; | |
| } | |
| interface ICTokenFlashloan { | |
| function flashLoan( | |
| address receiver, | |
| uint amount, | |
| bytes calldata params | |
| ) external; | |
| } | |
| interface IRouter{ | |
| function swapExactTokensForTokens( | |
| uint amountIn, | |
| uint amountOutMin, | |
| address[] calldata path, | |
| address to, | |
| uint deadline | |
| ) external returns (uint[] memory amounts); | |
| function getAmountsOut( | |
| uint amountIn, | |
| address[] calldata path | |
| ) external view returns (uint[] memory amounts); | |
| } | |
| contract FlashArbitrage is IFlashloanReceiver { | |
| address public owner; | |
| address public feePoolAddr; | |
| constructor() public { | |
| owner = msg.sender; | |
| feePoolAddr = msg.sender; | |
| } | |
| function setFeePoolAddress(address _feePoolAddr) public { | |
| require(msg.sender == owner, "unauthorized"); | |
| feePoolAddr = _feePoolAddr; | |
| } | |
| function arbitrage(IERC20 Capital, bytes memory params) internal { | |
| // parse params | |
| ( | |
| address buyFromThisRouterAddr, | |
| address sellToThisRouterAddr, | |
| address token1Addr, | |
| address token2Addr, | |
| uint deadline | |
| ) = abi.decode(params, ( | |
| address, | |
| address, | |
| address, | |
| address, | |
| uint | |
| )); | |
| // prepare routers | |
| IRouter buyFromThisRouter = IRouter(buyFromThisRouterAddr); | |
| IRouter sellToThisRouter = IRouter(sellToThisRouterAddr); | |
| // make buy order | |
| address[] memory pair1 = new address[](2); | |
| pair1[0] = token1Addr; | |
| pair1[1] = token2Addr; | |
| uint256 amount2 = buyFromThisRouter.getAmountsOut(Capital.balanceOf(address(this)), pair1)[1]; | |
| buyFromThisRouter.swapExactTokensForTokens(Capital.balanceOf(address(this)), amount2, pair1, address(this), deadline); // buy | |
| // make sell order | |
| address[] memory pair2 = new address[](2); | |
| pair2[0] = token2Addr; | |
| pair2[1] = token1Addr; | |
| sellToThisRouter.swapExactTokensForTokens(amount2, sellToThisRouter.getAmountsOut(amount2, pair2)[1], pair2, address(this), deadline); // sell | |
| } | |
| function doFlashArbitrage(address lenderAddr, uint256 borrowAmount, bytes calldata params) external payable { | |
| ICTokenFlashloan(lenderAddr).flashLoan(address(msg.sender), borrowAmount, params); | |
| } | |
| function executeOperation(address signerAddr, address tokenAddr, uint amount, uint fee, bytes calldata params) external payable { | |
| IERC20 Capital = IERC20(tokenAddr); | |
| require(Capital.balanceOf(address(this)) >= amount, "Invalid balance, was the flashLoan successful?"); | |
| arbitrage(Capital, params); | |
| require(Capital.transfer(msg.sender, amount + fee), "Transfer fund back failed"); | |
| Capital.transfer(feePoolAddr, Capital.balanceOf(address(this))/10); // deduct 10% to fee pool | |
| Capital.transfer(signerAddr, Capital.balanceOf(address(this))); // transfer remaining to signer | |
| } | |
| } |
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