First Flight #11: Snek-Raffle
First Flight #11
Beginner FriendlyFoundryNFT
100 EXP
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Submission Details
Severity: low
Invalid

The `request_raffle_winner` function should emit an event `RequestedRaffleWinner` and return `request_id`

bube

Summary

The request_raffle_winner returns the total supply of NFTs instead the request_id and doesn't emit an event RequestedRaffleWinner.

Vulnerability Details

The request_raffle_winner function should get a random winner.

​
@external
def request_raffle_winner() -> uint256:
"""Request a random winner from the VRF Coordinator after a raffle has completed."""
is_open: bool = RaffleState.OPEN == self.raffle_state
time_passed: bool = (block.timestamp - self.last_timestamp) > RAFFLE_DURATION
has_players: bool = len(self.players) > 0
has_balance: bool = self.balance > 0
assert is_open and time_passed and has_players and has_balance, ERROR_NOT_ENDED
​
self.raffle_state = RaffleState.CALCULATING
request_id: uint256 = VRF_COORDINATOR.requestRandomWords(
GAS_LANE,
SUBSCRIPTION_ID,
REQUEST_CONFIRMATIONS,
CALLBACK_GAS_LIMIT,
NUM_WORDS
)
@> return ERC721._total_supply()
​

But actually the function returns the total supply of the NFTs. That can lead to confusion that the total supply of the NFTs is the request_id.
Also, there is an event RequestedRaffleWinner in events section:

​
event RequestedRaffleWinner:
request_id: indexed(uint256)
​

But this event is never emitted.

Impact

The function request_raffle_winner returns the total supply of NFTs instead of the request_id. That leads to misunderstanding what is the correct value of the request_id.
The function also doesn't emit an event RequestedRaffleWinner. In that way there is no way to understand if the function successfully has retrieved the request_id.

Tools Used

Manual Review

Recommendations

Change the return value of the request_raffle_winner function and emit an event RequestedRaffleWinner:

​
@external
def request_raffle_winner() -> uint256:
"""Request a random winner from the VRF Coordinator after a raffle has completed."""
is_open: bool = RaffleState.OPEN == self.raffle_state
time_passed: bool = (block.timestamp - self.last_timestamp) > RAFFLE_DURATION
has_players: bool = len(self.players) > 0
has_balance: bool = self.balance > 0
assert is_open and time_passed and has_players and has_balance, ERROR_NOT_ENDED
​
self.raffle_state = RaffleState.CALCULATING
request_id: uint256 = VRF_COORDINATOR.requestRandomWords(
GAS_LANE,
SUBSCRIPTION_ID,
REQUEST_CONFIRMATIONS,
CALLBACK_GAS_LIMIT,
NUM_WORDS
)
+ log RequestedRaffleWinner(request_id)
+ return request_id
- return ERC721._total_supply()
​
Updates

Lead Judging Commences

inallhonesty Lead Judge over 1 year ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity
Assigned finding tags:

Returning Total Supply Instead of Request ID in request_raffle_winner

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