First Flight #2: Puppy Raffle

Summary

User can enter raffle for free.

Vulnerability Details

The require statement in the enterRaffle function dictates that the msg.value has to be equal to the product of the entrance fee and the number of users being entered.
There is no check to ensure that the entranceFee is not Zero. In the case where it is zero, the user ends up paying no
wei for entering the raffle;effectively entering for free!

Impact

The Protocol can get cheated.

Tools Used

Manual

Recommendations

Revert if entranceFee <= 0