Router Code Style Findings

RRE-01C: Inefficient Token Transfers

Type	Severity	Location
Gas Optimization		Router.sol:L73-L79, L88-L92

Description:

The Router::withdrawFromEscrowAndCreateAuction function will withdraw the full available balance from the old escrow address towards the msg.sender and perform another transfer from the msg.sender towards the new escrow address to satisfy the notional value of the auction.

This transfer path is inefficient in case the withdrawal from the old escrow is less-than-or-equal to the notional value of the new auction.

Impact:

The Router::withdrawFromEscrowAndCreateAuction function is presently inefficient if the old escrow possesses the same notional value as the new escrow address, a common use case for this particular function.

Example:

Copy
62function withdrawFromEscrowAndCreateAuction(
63    address oldEscrow,
64    address escrowOwner,
65    DataTypes.AuctionInitialization calldata auctionInitialization
66) external {
67    if (!isEscrow[oldEscrow]) {
68        revert Errors.NotAnEscrow();
69    }
70    if (msg.sender != IEscrow(oldEscrow).owner()) {
71        revert Errors.InvalidSender();
72    }
73    IEscrow(oldEscrow).handleWithdraw(
74        msg.sender,
75        auctionInitialization.underlyingToken,
76        IERC20Metadata(auctionInitialization.underlyingToken).balanceOf(
77            oldEscrow
78        )
79    );
80    (address newEscrow, uint256 oTokenIndex) = _createEscrow();
81    IEscrow(newEscrow).initializeAuction(
82        address(this),
83        escrowOwner,
84        getExerciseFee(),
85        auctionInitialization,
86        oTokenIndex
87    );
88    IERC20Metadata(auctionInitialization.underlyingToken).safeTransferFrom(
89        msg.sender,
90        newEscrow,
91        auctionInitialization.notional
92    );
93    emit WithdrawFromEscrowAndCreateAuction(
94        escrowOwner,
95        oldEscrow,
96        newEscrow,
97        auctionInitialization
98    );
99}

Recommendation:

We advise a direct transfer from the old escrow contract to the new escrow contract to be performed if the notional value of the new auction is greater than the old escrow contract's balance, fulfilling any difference from the msg.sender directly if needed.

Alleviation (d9eb549dcca601db1fa91336ebe4d08fa8f2908b):

The code's transfer flows were optimized as advised, ensuring that the code will withdraw to the new escrow address directly if we are effectively replacing an old escrow with a new one, optimizing the code's gas cost in its most common use-case scenario.

RRE-02C: Repetitive Value Literal

Type	Severity	Location
Code Style		Router.sol:L25, L740

Description:

The linked value literal is repeated across the codebase multiple times.

Example:

Copy
25bytes4(keccak256("isValidSignature(bytes32,bytes)"));

Recommendation:

We advise it to be set to a constant variable instead, optimizing the legibility of the codebase.

In case the constant has already been declared, we advise it to be properly re-used across the code.

Alleviation (d9eb549dcca601db1fa91336ebe4d08fa8f2908b):

The EIP1271_IS_VALID_SELECTOR constant was renamed to EIP1271_SIG_AND_MAGIC_VALUE and was properly set to replace the 0x1626ba7e literal within the Router::_checkEIP1271Signature function, increasing the legibility of the codebase as advised.