20、智能合约安全与设计决策

智能合约安全与设计决策

智能合约安全

1. 利用提取模式修改合约

可以使用提取模式对 BecomeTheKing 合约进行修改，代码如下：

pragma solidity ^0.4.24;
contract BecomeTheKing {
    address currentKing;
    uint highestBid;
    mapping(address => uint) balances;
    // Function to withdraw previous bids
    function withdraw() public {
        uint balance = balances[msg.sender];
        require(balance > 0);
        balances[msg.sender] = 0;
        msg.sender.transfer(balance);
    }
    function() public payable {
        require(msg.value > highestBid);
        // Save the previous bid for withdrawal
        balances[msg.sender] = highestBid;
        currentKing = msg.sender;
        highestBid = msg.value;
    }
}

2.