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

The request_raffle_winner function fails to emit or log the RequestedRaffleWinner event. Could potentially lead to communication issues with DApps.

theirrationalone

Summary

The request_raffle_winner function doesn't emits/logs RequestRaffleWinner event. Since logs records are great resource of information and events in blockchain technology are essential for creating dynamic, responsive, and interoperable decentralized applications. They enable smart contracts to communicate, interact, and trigger off-chain processes, making blockchain technology more versatile and useful in a wide range of applications.

Vulnerability Details

Raffle expects to emit or log the request_raffle_winner event.

Checkout the Line 81 and Line 137

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# Events
event RequestedRaffleWinner:
----------------^
request_id: indexed(uint256)
event RaffleEntered:
player: indexed(address)
event WinnerPicked:
player: indexed(address)
​
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@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
)
------> # No Log emmission.
return ERC721._total_supply()
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Impact

This omission results in the absence of a log record for the raffle spin request for the winner, which could potentially lead to communication issues with DApps.

Tools Used

Manual Review

Recommendations

Log/Emit the RequestedRaffleWinner after a successful Raffle spin winner request. Update snek_raffle.vy like below...

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@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 RaffleEntered(request_id)
return ERC721._total_supply()
​
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Updates

Lead Judging Commences

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

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