Marketplace

Names could be transferred to an NFT with an existing name but the tokenByName mapping still contains the overwritten name pointing to the NFT. As a result, two different names may point to the same NFT.

Consider the following scenario:

1. Alice owns an NFT with name “Alice”
2. Bob owns an NFT with name “Bob”
3. Name “Alice” is transferred to Bob’s NFT
4. tokenByName is updated to reflect that “Alice” points to Bob’s NFT.
5. tokenByName still has an entry for name “Bob” also pointing to Bob’s NFT.
6. It now appears that Bob is now the owner of both names “Bob” and “Alice”.
7. A user purchases name “Bob” but ends up receiving name “Alice” upon transfer.

If a name may be transferred to an NFT with an existing name, dereserve the old name using releaseTokenByName.

Initially, when no bids have been entered, the existing bid will have default values – address(0) as the collection and 0 for the tokenId. The zero address does not have function ownerOf, so the call to getOwner will revert. As a result, no bids can be entered.

Bypass the ownership check when there are no existing bids.

When a bid is accepted through acceptBidForName or an offered name is purchased through buyName, there is no check that the NFT the name shall be transferred to is already named. As a result, a user may unexpectedly lose their old name upon transfer.

Consider if owned names should be overwritten upon transfer. If necessary, clearly document such behavior.

It is simple for a malicious actor to grief a seller by placing a bid higher than the previous and then withdrawing the bid or transferring the tokenTo to another address. As a result, any bids made with true buying intention are lost and the seller is unable to sell his name.

Consider allowing for a few blocks to pass before the bid can be overwritten so that a malicious actor risks losing the funds sent to make the ineffectual bid.

string memory name = toLower(nftr.tokenName(collectionFrom, tokenFrom))

is performed after the transfer is already made. As a result, the event doesn’t emit the name that has been transferred but the empty string.

Grab the name from the toToken or cache the name prior to transfer.

There may be potential issues stemming from name parameters being lowered when getting the NFT with the provided name, but the encodedName being produced from a non-parsed input.

Consider the following scenario:

1. Bob owns an NFT with name “DIGITAL”
2. Alice calls enterBidForName and passes “digital” for the name parameter.
3. Bob calls acceptBidForName with name “DIGITAL”, but the encoded name does not match the encoded name generated by Alice’s “digital”.
4. Bob’s transaction reverts and is unable to accept Alice’s bid.

Lower the inputted name prior to encoding.

If the owner changes the feePerc, even if they lower it, all offers with a different fee will need to be reset due to a fee mismatch. A seller would prefer a lower fee so it is unexpected for their offer to be rendered invalid.

Compare the offer’s fee percentage against an upper bound rather than an exact check.

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There is potential for a user to be unable to withdraw their bid.

Consider the following scenario:

1. Bob bids for the name “Alice”.
2. He then receives the NFT named “Alice” through secondary markets or a direct transfer.
3. Bob is unable to withdraw his bid value because he now owns the NFT named “Alice”.

Consider whether it is necessary to check for ownership when withdrawing a bid for a name.

If necessary, properly document such behavior for users.

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_WETH is already an address so it is unnecessary to cast it to one.

Remove address(_WETH) cast.

delete on a mapping entry can be used to reset to defaults rather than setting a zeroed off Offer/Bid.

Consider using delete if only default values are necessary.

toLower has visibility public but it under the internal functions section.

Consider marking the function with visibility internal or move it to a different section.

The length of bStr can be cached. Furthermore, because a name’s length is restricted in NFTR, the index can be incremented in a unchecked block.

Consider the above gas optimizations.