Christmas Dinner

the key security fixes made to the original contract:

1. Reentrancy Protection Fix

   • Before: receive() and other functions were vulnerable to reentrancy

   • Fixed by:

     import { ReentrancyGuard } from "...ReentrancyGuard.sol";

     contract ChristmasDinner is ReentrancyGuard {

     // Added nonReentrant modifier to critical functions

     receive() external payable nonReentrant beforeDeadline {

2. Deadline Enforcement Fix

   • Before: Participation could be toggled after deadline

   • Fixed by:

     function changeParticipationStatus() external beforeDeadline {

     bool newStatus = !participants[msg.sender];

     participants[msg.sender] = newStatus;

     emit ChangedParticipation(msg.sender, newStatus);

     }

3. Deposit Limit Fix

   • Before: No limit on deposits, risk of overflow

   • Fixed by:

     uint256 private constant MAX_DEPOSIT = 1000 ether;

     ​

     if (msg.value > MAX_DEPOSIT) revert ExceedsMaxDeposit();

4. Host Management Security Fix

   • Before: Single-step host change was risky

   • Fixed by adding two-step process:

     function proposeNewHost(address _newHost) external onlyHost {

     // ... validation

     }

     ​

     function acceptHostRole() external {

     // ... time-bound acceptance

     }

5. Token Whitelist Security Fix

   • Before: Whitelist could potentially be modified

   • Fixed by:

     mapping(address => bool) public immutable whitelistedTokens;

6. ETH Transfer Security Fix

   • Before: Used .transfer() which could fail

   • Fixed by:

     (bool success, ) = _to.call{value: ethBalance}("");

     require(success, "ETH transfer failed");

7. State Management Fix

   • Before: State changes after external calls

   • Fixed by implementing CEI pattern:

     // Update state before transfer

     etherBalances[msg.sender] = 0;

     participants[msg.sender] = false;

     // Then perform transfers

These fixes significantly improve the contract's security by:

• Preventing reentrancy attacks

• Enforcing proper deadline checks

• Adding deposit limits

• Implementing secure host transfers

• Protecting the token whitelist

• Using safer ETH transfer methods

• Following best practices for state management