[Unstoppable] is convertToShares the right function?

[bshyuunn]

Hello everyone !

There's something I don't understand about the flashLoan function in the Unstoppable problem!

Here, convertToShares(totalSupply) returns Shares and balanceBefore seems to represent assets. These two values obviously represent different values. Shouldn't convertToAssets be used instead of convertToShares?

Thanks for helping me!!

    function flashLoan(
        IERC3156FlashBorrower receiver,
        address _token,
        uint256 amount,
        bytes calldata data
    ) external returns (bool) {
        if (amount == 0) revert InvalidAmount(0); // fail early
        if (address(asset) != _token) revert UnsupportedCurrency(); // enforce ERC3156 requirement
        uint256 balanceBefore = totalAssets();
        if (convertToShares(totalSupply) != balanceBefore) revert InvalidBalance(); // enforce ERC4626 requirement
        uint256 fee = flashFee(_token, amount);
        // transfer tokens out + execute callback on receiver
        ERC20(_token).safeTransfer(address(receiver), amount);
        // callback must return magic value, otherwise assume it failed
        if (receiver.onFlashLoan(msg.sender, address(asset), amount, fee, data) != keccak256("IERC3156FlashBorrower.onFlashLoan"))
            revert CallbackFailed();
        // pull amount + fee from receiver, then pay the fee to the recipient
        ERC20(_token).safeTransferFrom(address(receiver), address(this), amount + fee);
        ERC20(_token).safeTransfer(feeRecipient, fee);
        return true;
    }

I've seen this discussion but can't understand it...

[tinchoabbate]

Hi @bshyuunn, it's common to find yourself in these situations when you start playing Damn Vulnerable DeFi.

The code is full of this kind of cases, where you don't know if what you're seeing is a problem. That's the challenge! Figuring out whether it is a problem or not. And if it is, whether it may open a path to solving the challenge.

I know I'm not answering your question directly. I don't want to spoil any answers here. Keep digging!

[bshyuunn]

thanks for answering!!