合约调用ERC20 transfer/transferFrom触发revert错误求助

问题现象 #

每次调用合约的bet函数尝试转账ERC20代币时，都会触发如下revert错误：
Note: The called function should be payable if you send value and the value you send should be less than your current balance.

合约代码 #

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

interface IERC20 {
    function totalSupply() external view returns (uint);

    function balanceOf(address account) external view returns (uint);

    function transfer(address recipient, uint amount) external returns (bool);

    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint amount) external returns (bool);

    function transferFrom(
        address sender,
        address recipient,
        uint amount
    ) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint value);
    event Approval(address indexed owner, address indexed spender, uint value);
}

contract Hilo {
    uint public fee;
    uint256 public maxBet;
    uint256 public minBet;
    address public owner;
    IERC20 public immutable token;


    constructor(address _tradeToken, uint initialFee, uint256 initalMaxBet, uint256 initalMinBet) {
        fee = initialFee;
        maxBet = initalMaxBet;
        minBet = initalMinBet;
        owner = msg.sender;
        token = IERC20(_tradeToken);
    }

    modifier onlyOwner() {
        require(msg.sender == owner, "Not owner");
        _;
    }

    function changeFee(uint newFee) public onlyOwner  {
        fee = newFee;
    }

    function changeMaxBet(uint newMaxBet) public onlyOwner  {
        maxBet = newMaxBet;
    }

    function changeMinBet(uint newMinBet) public onlyOwner {
        maxBet = newMinBet;
    }

    function bet(uint card, string memory choice, uint256 amount, uint256 multiplier) external returns (uint nextCard) {
        require(amount <= maxBet, "amount is greater than the maxBet");
        require(amount >= minBet, "amount is smaller than minBet");
        uint256 newAmount = amount * (fee / 1000);
        require(token.balanceOf(msg.sender) >= newAmount, "Token transfer failed.");
        token.transferFrom(msg.sender, address(this), newAmount);
        uint next = uint(keccak256(abi.encodePacked(block.timestamp, block.difficulty,  
        msg.sender))) % 13 + 1; 
        if (keccak256(abi.encodePacked(choice)) == keccak256(abi.encodePacked('L'))) {
            if (card > next) {
                token.transfer(msg.sender, amount * (multiplier / 100));
                return next;
            } 
        } else if (keccak256(abi.encodePacked(choice)) == keccak256(abi.encodePacked('H'))) {
            if (card < next) {
                token.transfer(msg.sender, amount * (multiplier / 100));
                return next;
            }
        }

        return next;
    }
}

环境说明 #

使用Remix虚拟机环境，ERC20代币已成功部署。移除合约中的transfer或transferFrom调用后代码可正常运行；直接调用ERC20合约的transferFrom方法（完成授权后）能正常工作，排除单纯的授权错误（授权错误有专属提示）。

问题根源 #

1. 整数除法精度丢失：
   代码中uint256 newAmount = amount * (fee / 1000);的计算顺序错误，fee通常是小于1000的数值（比如5代表0.5%手续费），fee / 1000会因Solidity整数除法向下取整得到0，最终newAmount为0。部分ERC20合约会拒绝0金额转账，触发异常。
2. 缺失授权额度检查：
   transferFrom执行的前提是用户已授权合约足够额度，当前代码仅检查用户余额，未验证allowance(msg.sender, address(this)) >= newAmount，若授权不足会导致转账失败。
3. changeMinBet函数笔误：
   该函数内错误地修改了maxBet变量而非minBet，导致最小投注额配置失效，可能引发后续逻辑异常。

修复方案 #

1. 修正手续费计算逻辑：
   调整计算顺序为先乘后除，避免精度丢失：

   uint256 newAmount = amount * fee / 1000;
   

2. 添加授权检查：
   在transferFrom调用前增加授权验证：

   require(token.allowance(msg.sender, address(this)) >= newAmount, "Insufficient allowance");
   

3. 修复changeMinBet函数：
   将函数内的maxBet = newMinBet;改为：

   minBet = newMinBet;
   

4. 显式检查转账返回值：
   部分ERC20合约转账失败时返回false而非revert，建议显式检查返回值：

   require(token.transferFrom(msg.sender, address(this), newAmount), "TransferFrom failed");
   require(token.transfer(msg.sender, amount * multiplier / 100), "Transfer failed");
   

内容的提问来源于stack exchange，提问作者fwara07