fix: audit gas refund logic #24
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Important Review skippedAuto reviews are disabled on base/target branches other than the default branch. Please check the settings in the CodeRabbit UI or the You can disable this status message by setting the 📝 WalkthroughWalkthroughThe pull request introduces a refined error handling mechanism across multiple contracts, specifically in Changes
Sequence DiagramsequenceDiagram
participant Sender
participant Contract
participant Gateway
Sender->>Contract: Initiate Cross-Chain Transfer
Contract->>Gateway: Attempt Gas Token Transfer
alt Gas Transfer Fails
Contract->>Contract: Emit RefundFailed Event
Contract->>Sender: Log Failure Details
else Gas Transfer Succeeds
Gateway->>Contract: Process Transfer
end
The sequence diagram illustrates the new error handling flow, where instead of reverting on a failed gas token transfer, the contract now emits a Thank you for using CodeRabbit. We offer it for free to the OSS community and would appreciate your support in helping us grow. If you find it useful, would you consider giving us a shout-out on your favorite social media? 🪧 TipsChatThere are 3 ways to chat with CodeRabbit:
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Actionable comments posted: 0
🧹 Nitpick comments (2)
contracts/nft/contracts/shared/Events.sol (1)
31-31: Consider enhancing event parameter naming and indexingThe
RefundFailedevent parameters should be named and indexed for better readability and efficient event filtering.-event RefundFailed(address, uint256); +event RefundFailed(address indexed recipient, uint256 amount);contracts/nft/contracts/evm/UniversalNFT.sol (1)
142-142: Ensure NFT state consistency with non-blocking refundsWhile the change aligns with UniversalToken.sol, NFTs require special consideration:
- The NFT is minted and ownership transferred before the refund attempt
- Failed refunds could leave users with valid NFTs but lost gas funds
Consider:
- Documenting the new behavior in contract comments
- Adding a recovery mechanism specific to NFT transfers
if (gasAmount > 0) { if (sender == address(0)) revert InvalidAddress(); (bool success, ) = payable(sender).call{value: gasAmount}(""); - if (!success) emit RefundFailed(sender, gasAmount); + if (!success) { + // Document: NFT transfer successful but gas refund failed + emit RefundFailed(sender, gasAmount); + // Consider: Add to a recovery mapping for later claiming + } }
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📒 Files selected for processing (4)
contracts/nft/contracts/evm/UniversalNFT.sol(1 hunks)contracts/nft/contracts/shared/Events.sol(1 hunks)contracts/token/contracts/evm/UniversalToken.sol(1 hunks)contracts/token/contracts/shared/Events.sol(1 hunks)
✅ Files skipped from review due to trivial changes (1)
- contracts/token/contracts/shared/Events.sol
🔇 Additional comments (1)
contracts/token/contracts/evm/UniversalToken.sol (1)
115-115: Consider implications of non-blocking gas refunds
The change from reverting to event emission on refund failure introduces potential silent failures. While this prevents transaction reversion, it may lead to:
- Lost gas refunds without user notification
- Inconsistent state between successful token transfer but failed refund
Consider:
- Adding logging with detailed failure reason
- Implementing a recovery mechanism for failed refunds
| @@ -140,7 +139,7 @@ contract UniversalNFT is | |||
| if (gasAmount > 0) { | |||
| if (sender == address(0)) revert InvalidAddress(); | |||
| (bool success, ) = payable(sender).call{value: gasAmount}(""); | |||
| if (!success) revert GasTokenTransferFailed(); | |||
| if (!success) emit RefundFailed(sender, gasAmount); | |||
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i am not sure i understand this, so for example if we refund to smart contract, and it fails, lets say smart contract doesn't have receiver function by mistake - we let tx succeed even though funds are not transfered, do we then transfer funds manually?
it doesn't look like a security issue to me, would be nice to add exploit scenario to issue for better understanding
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Right now tokens just remain in the contract. I suppose we can implement a recover function so that the owner can recover these tokens.
function recover(address tokenAddress, uint256 tokenAmount) public onlyOwner {
if (tokenAddress == address(0)) {
payable(owner()).transfer(tokenAmount);
} else {
IERC20(tokenAddress).transfer(owner(), tokenAmount);
}
Summary by CodeRabbit
New Features
RefundFailedevent to log instances of failed gas token transfers in bothUniversalNFTandUniversalTokencontracts.Bug Fixes
GasTokenTransferFailederror, improving error handling for gas token transfers by shifting to event-based notifications.