LI.FI contest - TerrierLover's results

Use uint256 instead of uint8 at for loop at Swapper.sol and HopFacet.sol

Target codebase

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/Swapper.sol#L14

for (uint8 i; i < _swapData.length; i++) {
    require(
        ls.dexWhitelist[_swapData[i].approveTo] == true && ls.dexWhitelist[_swapData[i].callTo] == true,
        "Contract call not allowed!"
    );

    LibSwap.swap(_lifiData.transactionId, _swapData[i]);
}

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/HopFacet.sol#L48-L50

for (uint8 i; i < _tokens.length; i++) {
    s.hopBridges[_tokens[i]] = _bridgeConfigs[i];
}

Usage of uint8 increases the gas fee. If switching this to uint256 is possible for the product, it can reduce the gas fee.

Proposed implementations

Just use uint256 instead of uint8.

for (uint256 i; i < _swapData.length; i++) {
    require(
        ls.dexWhitelist[_swapData[i].approveTo] == true && ls.dexWhitelist[_swapData[i].callTo] == true,
        "Contract call not allowed!"
    );

    LibSwap.swap(_lifiData.transactionId, _swapData[i]);
}

for (uint256 i; i < _tokens.length; i++) {
    s.hopBridges[_tokens[i]] = _bridgeConfigs[i];
}

Gas improvements

Gas fees of methods and deployments are decreased by using uint256 instead of uint8.

Methods - average gas change

Deployments - average gas change

---

== true check is not needed at _executeSwaps function in Swapper.sol

Target codebase

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/Swapper.sol#L16

require(
    ls.dexWhitelist[_swapData[i].approveTo] == true && ls.dexWhitelist[_swapData[i].callTo] == true,
    "Contract call not allowed!"
);

When checking boolean value, it does not need to check == true.

Proposed implementations

Following code has same meaning.

require(
    ls.dexWhitelist[_swapData[i].approveTo] && ls.dexWhitelist[_swapData[i].callTo],
    "Contract call not allowed!"
);

Gas improvements

Confirmed that the gas fees of deployments and methods decreased.

---

Usage of != 0 instead of > 0 can reduce the gas fee slightly

Target codebase

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/HopFacet.sol#L109 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/AnyswapFacet.sol#L92 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/AnyswapFacet.sol#L105 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/CBridgeFacet.sol#L105 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/CBridgeFacet.sol#L116 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/NXTPFacet.sol#L98 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Libraries/LibAsset.sol#L67 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Libraries/LibDiamond.sol#L84 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Libraries/LibDiamond.sol#L102 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Libraries/LibDiamond.sol#L121 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Libraries/LibDiamond.sol#L189 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Libraries/LibDiamond.sol#L196 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Libraries/LibDiamond.sol#L212

Proposed implementations

Use != 0 instead of > 0. Example code is as follows:

require(contractSize != 0, _errorMessage);

Gas improvements

Confirmed that the gas fees of deployments and methods decreased.

---

Avoid using == true or == false at DexManagerFacet.sol

Target codebase

Where == true is used

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/DexManagerFacet.sol#L20

if (s.dexWhitelist[_dex] == true) {
    return;
}

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/DexManagerFacet.sol#L34

if (s.dexWhitelist[_dexs[i]] == true) {
    continue;
}

Where == false is used

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/DexManagerFacet.sol#L47

if (s.dexWhitelist[_dex] == false) {
    return;
}

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/DexManagerFacet.sol#L66

if (s.dexWhitelist[_dexs[i]] == false) {
    continue;
}

Proposed implementations

Where == true is used

if (s.dexWhitelist[_dex]) {
    return;
}

if (s.dexWhitelist[_dexs[i]]) {
    continue;
}

Where == false is used

if (!s.dexWhitelist[_dex]) {
    return;
}

if (!s.dexWhitelist[_dexs[i]]) {
    continue;
}

Gas improvements

Confirmed that the gas fees of deployments and methods slightly decreased.

---