First Flight #2: Puppy Raffle

Summary

'enterRaffle' function might fail

Vulnerability Details

'enterRaffle' function might fail if the list of players is too big

Impact

The smart contract will not allow new players to enter the raffle and the gas costs will increase for every new player because we use two 'for' loops to check for duplicates.

Tools Used

Manual Review

Recommendations

Modify the 'enterRaffle' function like this
uint256 private round; // We increase it after we choose the winner
mapping(address -> mapping(uint256 => bool)) public isPlayerInRound;
mapping (uint256 => uint256) public totalPlayersInRound;

function enterRaffle(address[] memory newPlayers) public payable {
    require(msg.value == entranceFee * newPlayers.length, "PuppyRaffle: Must send enough to enter raffle");
    for (uint256 i = 0; i < newPlayers.length; {
        if(isPlayerInRound[newPlayers[i]][round] || newPlayers[i] == address(0)) revert("PuppyRaffle: Duplicate player");
        isPlayerInRound[newPlayers[i]][round] = true;

        unchecked {
            ++totalPlayersInRound[round];
            ++i;
        }
    }

    emit RaffleEnter(newPlayers);
}