CCDMClient Code Style Findings

CCM-01C: Generic Typographic Mistakes

Type	Severity	Location
Code Style		CCDMClient.sol:L29, L30, L31, L32, L33

Description:

The referenced lines contain typographical mistakes (i.e. private variable without an underscore prefix) or generic documentational errors (i.e. copy-paste) that should be corrected.

Example:

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29ExtAddr _ccdmHost;

Recommendation:

We advise them to be corrected enhancing the legibility of the codebase.

Alleviation (58e8cc66dfa900c03c47df78f5170d9960005629):

All referenced variables have been renamed accordingly, omitting their underscore prefix for the sake of legibility as they do not constitute actual private / internal variables.

CCM-02C: Ineffectual Usage of Safe Arithmetics

Type	Severity	Location
Language Specific		CCDMClient.sol:L140

Description:

The linked mathematical operation is guaranteed to be performed safely by surrounding conditionals evaluated in either require checks or if-else constructs.

Example:

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139if (spent < msg_.amount) {
140    _processRefund(msg_.receiver, msg_.token, msg_.amount - spent);
141}

Recommendation:

Given that safe arithmetics are toggled on by default in pragma versions of 0.8.X, we advise the linked statement to be wrapped in an unchecked code block thereby optimizing its execution cost.

Alleviation (58e8cc66dfa900c03c47df78f5170d9960005629):

The refund calculation has been properly wrapped in an unchecked code block safely, optimizing its gas cost.

CCM-03C: Inefficient Duplicate Query of Storage Location

Type	Severity	Location
Gas Optimization		CCDMClient.sol:L130, L153

Description:

The CCDMClient::_handle function will invoke the CCDMClient::_processSpent function and both functions will re-calculate the storage location of the VaultInfo structure redundantly.

Example:

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125function _handle(uint32, bytes32, bytes calldata rawMsg) internal {
126    MsgDeposit memory msg_ = Message.decodeDeposit(rawMsg);
127
128    StorageV1 storage $ = _getStorageV1();
129
130    VaultInfo storage info = $._vaults[$._vaultIdxByL1Asset[msg_.token]];
131
132    ISudoVault vault = info.vault;
133
134    if (address(vault) == address(0x0)) {
135        revert Error.InvalidDepositRequest("non-registered asset");
136    }
137
138    try vault.manualDeposit(msg_.amount, msg_.receiver.toAddress()) returns (uint256 spent) {
139        if (spent < msg_.amount) {
140            _processRefund(msg_.receiver, msg_.token, msg_.amount - spent);
141        }
142        _processSpent(msg_.receiver, msg_.token, spent);
143        emit DepositSuccess(msg_.receiver.toAddress(), info.l1Asset, info.l2Asset, spent);
144    } catch {
145        _processRefund(msg_.receiver, msg_.token, msg_.amount);
146        emit DepositFailure(msg_.receiver.toAddress(), info.l1Asset, info.l2Asset, msg_.amount);
147    }
148}
149
150function _processSpent(bytes32, bytes32 token, uint256 amount) internal {
151    StorageV1 storage $ = _getStorageV1();
152
153    $._vaults[$._vaultIdxByL1Asset[token]].unresolved += amount;
154}

Recommendation:

We advise the CCDMClient::_processSpent function to accept a VaultInfo storage argument that is consequently utilized to increment its unresolved data point, optimizing the function's gas cost.

Alleviation (58e8cc66dfa900c03c47df78f5170d9960005629):

The code instead updated all _process prefixed functions to accept the storage pointer as an argument, optimizing the gas cost of the function throughout.

CCM-04C: Inefficient Loop Limit Evaluation

Type	Severity	Location
Gas Optimization		CCDMClient.sol:L76

Description:

The linked for loop evaluates its limit inefficiently on each iteration.

Example:

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76for (uint256 i = 0; i < $._vaults.length; i++) {

Recommendation:

We advise the statements within the for loop limit to be relocated outside to a local variable declaration that is consequently utilized for the evaluation to significantly reduce the codebase's gas cost. We should note the same optimization is applicable for storage reads present in such limits as they are newly read on each iteration (i.e. length members of arrays in storage).

Alleviation (58e8cc66dfa900c03c47df78f5170d9960005629):

The Mitosis team evaluated this exhibit but opted to acknowledge it in the current iteration of the codebase

CCM-05C: Loop Iterator Optimization

Type	Severity	Location
Gas Optimization		CCDMClient.sol:L76

Description:

The linked for loop increments / decrements the iterator "safely" due to Solidity's built-in safe arithmetics (post-0.8.X).

Example:

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76for (uint256 i = 0; i < $._vaults.length; i++) {

Recommendation:

We advise the increment / decrement operation to be performed in an unchecked code block as the last statement within the for loop to optimize its execution cost.

Alleviation (0d29218ad3c34106523fd3eaab2f5336ab028c36):

The optimization has been regressed by removing the referenced unchecked code block and thus rendering this exhibit acknowledged.

CCM-06C: Suboptimal Struct Declaration Styles

Type	Severity	Location
Code Style		CCDMClient.sol:L85, L117

Description:

The linked declaration styles of the referenced structs are using index-based argument initialization.

Example:

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85Message.encodeBridge(MsgBridge(address(info.vault).toBytes32(), info.l1Asset, unresolved));

Recommendation:

We advise the key-value declaration format to be utilized instead in each instance, greatly increasing the legibility of the codebase.

Alleviation (0d29218ad3c34106523fd3eaab2f5336ab028c36):

The key-value declaration style is now properly in use within the referenced struct declarations, addressing this exhibit in full.