struct Order {
    address maker;
    bool isCall;
    bool isLong;
    address baseAsset;
    uint256 strike;
    uint256 premium;
    uint256 duration;
    uint256 expiration;
    uint256 nonce;
    address[] whitelist;
    address[] floorTokens;
    ERC20Asset[] erc20Assets;
    ERC721Asset[] erc721Assets;
}
function fillOrder(
    Order memory order,
    bytes calldata signature,
    uint256[] memory floorAssetTokenIds
) public payable returns (uint256 positionId) { // @audit-issue no re-entrancy guard
	..SNIP..
    // check msg.sender is allowed to fill the order
    require(order.whitelist.length == 0 || isWhitelisted(order.whitelist, msg.sender), "Not whitelisted");
	..SNIP..
}
function isWhitelisted(address[] memory whitelist, address target) public pure returns (bool) {
    for (uint256 i = 0; i < whitelist.length; i++) {
        if (target == whitelist[i]) return true;
    }

    return false;
}
