RabbitHole Quest Protocol contest - LethL's results

Findings Summary

[Gas-1] <x> += <y> costs more gas than <x> = <x> + <y> for state variables

Using x = x+y instead of x += y can help to save gas.

Instances(1):

File: Quest.sol

115:        redeemedTokens += redeemableTokenCount;

Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Quest.sol#L115

[Gas-2] Boolean Equality

Boolean constants can be used directly and do not need to be compared to true or false. Thus, this will cost more gas usage. Source: https://github.com/crytic/slither/wiki/Detector-Documentation#boolean-equality

Instances(3):

File: Quest.sol

136:        return claimedList[tokenId_] == true;

Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Quest.sol#L135

File: QuestFactory.sol

73:        if (rewardAllowlist[rewardTokenAddress_] == false) revert RewardNotAllowed();

221:        if (quests[questId_].addressMinted[msg.sender] == true) revert AddressAlreadyMinted();

Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L73 Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L221

[Gas-3] Use of Named Returns for Local Variables Saves Gas

Using named return values as temporary local variables can help you conserve gas. For example, the following code block can be refactored as follows:

File: RabbitHoleReceipt.sol

112:    ) public view returns (uint[] memory filteredTokens) {

125:        filteredTokens = new uint[](foundTokens);

Instances(1):

File: RabbitHoleReceipt.sol

112:    ) public view returns (uint[] memory) {

125:        uint[] memory filteredTokens = new uint[](foundTokens);

Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleReceipt.sol#L112 Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleReceipt.sol#L125

[Gas-4] Using a ternary operator instead of an "if-else" statement

Replacing an "if-else" statement with a ternary operator can help you save gas.

Instances(1):

File: QuestFactory.sol

143:        if (canCreateQuest_) {
144:            _grantRole(CREATE_QUEST_ROLE, account_);
145:        } else {
146:            _revokeRole(CREATE_QUEST_ROLE, account_);
147:        }

Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L143-L147

[Gas-5] Expressions for constant values such as a call to keccak256(), should use immutable rather than constant

The consequence of this is that the keccak256() operation is carried out each time the variable is utilized, leading to a rise in gas costs compared to just storing the calculated hash. By making it immutable, the hashing will only be done during contract deployment, which will reduce gas consumption.

Instances(1):

File: QuestFactory.sol

17:    bytes32 public constant CREATE_QUEST_ROLE = keccak256('CREATE_QUEST_ROLE');

Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L17

[Gas-6] Pre-calculate the hardcoded hash with keccak256() before and only use the result to save gas

Performing the hardcoded keccak256() hash calculation every time the contract is deployed or a function is called is less gas-efficient than pre-calculating the hash beforehand and using only its result.

Instances(3):

File: QuestFactory.sol

17:    bytes32 public constant CREATE_QUEST_ROLE = keccak256('CREATE_QUEST_ROLE');

72:        if (keccak256(abi.encodePacked(contractType_)) == keccak256(abi.encodePacked('erc20'))) {

105:        if (keccak256(abi.encodePacked(contractType_)) == keccak256(abi.encodePacked('erc1155'))) {

Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L17 Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L72 Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L105

[Gas-7] internal functions only called once can be inlined to save gas

Not inlining a function incurs an additional cost of 20 to 40 gas due to the requirement of two extra JUMP instructions and additional stack operations for function calls.

Instances(1):

File: QuestFactory.sol

152:    function grantDefaultAdminAndCreateQuestRole(address account_) internal {

Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L152

[Gas-8] Before some functions, we should check some variables for possible gas save

Before making a transfer, it is advisable to check if the amount is 0 to prevent the function from running and incurring gas costs unnecessarily when no transfer will occur.

Instances(5):

File: Erc20Quest.sol

60:        IERC20(rewardToken).safeTransfer(msg.sender, amount_); // check amount_

86:        IERC20(rewardToken).safeTransfer(to_, nonClaimableTokens); // check nonClaimableTokens

103:        IERC20(rewardToken).safeTransfer(protocolFeeRecipient, protocolFee()); // check protocolFee()

Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Erc20Quest.sol#L60 Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Erc20Quest.sol#L86 Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Erc20Quest.sol#L103

File: Erc1155Quest.sol

42:        IERC1155(rewardToken).safeTransferFrom(address(this), msg.sender, rewardAmountInWeiOrTokenId, amount_, '0x00'); // check amount_

60:        IERC1155(rewardToken).balanceOf(address(this), rewardAmountInWeiOrTokenId),

Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Erc1155Quest.sol#L42 Link to Code: https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Erc1155Quest.sol#L60