inheritance Art Rental Platform

Smart Contract Audit Report

Audit Summary

inheritance Art is releasing a new rental platform to allow users to list and rent NFTs.

For this audit, we reviewed the iAIRental contract.

We also reviewed the project team's token contract here and NFT Auction House contract here.

Audit Findings

No findings were identified, though some centralized aspects are present.
Date: July 19th, 2022.
Updated: July 27th, 2022 with the ability to add additional admins and a fee per NFT collection.

Contract Overview

This contract allows users to list their ERC721 or ERC1155 NFTs to be rented by other users.

Any address may list an NFT from a supported NFT collection.

Supported ERC721 collections must implement the ERC165 supportsInterface functionality.

The lister specifies the minimum and maximum length of time the NFT may be rented; the rental times must be between the platform's "rental floor" and the "rental ceiling".

A listing owner may update the minimum and maximum rental times for any of their listings to any value between the rental floor and rental ceiling at any time.

The NFT will cost the "daily rate" to rent per day.

A listing owner may update the daily rate for any of their listings to any amount at any time. This will not affect any current rentals.

There is no limit on a listing's daily rate.

Any address may rent an NFT with an active listing.

A listing owner may toggle the active status of any of their listings at any time. This will not affect any current rentals.

Users specify the amount of time they would like to rent the NFT, in number of days, between the listing's minimum and maximum rental times.

A platform fee is taken and transferred to the Platform Fee Recipient; the platform fee is dependent on the NFT collection the user is renting from and may vary between collections.

The rental cost after fees is sent to the listing owner.

Any extra ETH will be returned to the renting user.

A listing owner may withdraw any NFT they have listed that is not currently rented.

The owner or an approved admin address may toggle the supported status of any NFT collection at any time.

The owner or an approved admin address may update the rental floor and rental ceiling to any value at any time.

The owner or an approved admin address may set the fee for any supported NFT collection to any value, up to 50%, at any time.

The owner or an approved admin address may update the Platform Fee Recipient to any address at any time.

The owner may add and remove an address as an approved admin at any time.

As the contract is implemented with Solidity v0.8.10, it is safe from any possible overflows/underflows.

Audit Results

Inheritance Chart

Function Graph

Functions Overview

 ($) = payable function
 # = non-constant function
 
 Int = Internal
 Ext = External
 Pub = Public

 +  Context 
    - [Int] _msgSender
    - [Int] _msgData

 +  Ownable (Context)
    - [Pub] Constructor #
    - [Pub] owner
    - [Int] _checkOwner
    - [Pub] renounceOwnership #
       - modifiers: onlyOwner
    - [Pub] transferOwnership #
       - modifiers: onlyOwner
    - [Int] _transferOwnership #

 + [Int] IERC165 
    - [Ext] supportsInterface

 + [Int] IERC721 (IERC165)
    - [Ext] balanceOf
    - [Ext] ownerOf
    - [Ext] safeTransferFrom #
    - [Ext] safeTransferFrom #
    - [Ext] transferFrom #
    - [Ext] approve #
    - [Ext] setApprovalForAll #
    - [Ext] getApproved
    - [Ext] isApprovedForAll

 + [Int] IERC1155 (IERC165)
    - [Ext] balanceOf
    - [Ext] balanceOfBatch
    - [Ext] setApprovalForAll #
    - [Ext] isApprovedForAll
    - [Ext] safeTransferFrom #
    - [Ext] safeBatchTransferFrom #

 + [Int] IERC165Upgradeable 
    - [Ext] supportsInterface

 + [Int] IERC721Upgradeable (IERC165Upgradeable)
    - [Ext] balanceOf
    - [Ext] ownerOf
    - [Ext] safeTransferFrom #
    - [Ext] safeTransferFrom #
    - [Ext] transferFrom #
    - [Ext] approve #
    - [Ext] setApprovalForAll #
    - [Ext] getApproved
    - [Ext] isApprovedForAll

 + [Int] IERC1155Upgradeable (IERC165Upgradeable)
    - [Ext] balanceOf
    - [Ext] balanceOfBatch
    - [Ext] setApprovalForAll #
    - [Ext] isApprovedForAll
    - [Ext] safeTransferFrom #
    - [Ext] safeBatchTransferFrom #

 + [Lib] ERC165Checker 
    - [Int] supportsERC165
    - [Int] supportsInterface
    - [Int] getSupportedInterfaces
    - [Int] supportsAllInterfaces
    - [Prv] _supportsERC165Interface

 +  iAIRental (Ownable)
    - [Pub] Constructor #
    - [Ext] checkRentsFromCollection
    - [Pub] isListingRented
    - [Ext] listNFT #
    - [Ext] rent ($)
    - [Ext] updateRate #
    - [Ext] updateListingLimits #
    - [Ext] setActive #
    - [Ext] withdrawNFT #
    - [Ext] setCollectionSupported #
       - modifiers: onlyOwner
    - [Int] isERC721
    - [Pub] onERC721Received #
    - [Pub] onERC1155Received #
    - [Pub] getListingInfo
    - [Ext] adjustValidRentalWindowDays #
       - modifiers: onlyOwner
    - [Ext] setPlatformFeePercentage #
       - modifiers: onlyOwner
    - [Ext] setPlatformFeeRecipient #
       - modifiers: onlyOwner 

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Typically, a smart contract audit is a comprehensive review process designed to discover logical errors, security vulnerabilities, and optimization opportunities within code. A SourceHat Audit takes this a step further by verifying economic logic to ensure the stability of smart contracts and highlighting privileged functionality to create a report that is easy to understand for developers and community members alike.

How Do I Interpret the Findings?

Each of our Findings will be labeled with a Severity level. We always recommend the team resolve High, Medium, and Low severity findings prior to deploying the code to the mainnet. Here is a breakdown on what each Severity level means for the project:

• High severity indicates that the issue puts a large number of users' funds at risk and has a high probability of exploitation, or the smart contract contains serious logical issues which can prevent the code from operating as intended.
• Medium severity issues are those which place at least some users' funds at risk and has a medium to high probability of exploitation.
• Low severity issues have a relatively minor risk association; these issues have a low probability of occurring or may have a minimal impact.
• Informational issues pose no immediate risk, but inform the project team of opportunities for gas optimizations and following smart contract security best practices.

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