Asymmetry contest - inmarelibero's results

============================================================================================================== # 1 ==============================================================================================================

Abstract

At line #194 the wrong index is included in the event.

File: contracts/SafEth/SafEth.sol
182:     function addDerivative(
183:         address _contractAddress,
184:         uint256 _weight
185:     ) external onlyOwner {
186:         derivatives[derivativeCount] = IDerivative(_contractAddress);
187:         weights[derivativeCount] = _weight;
188:         derivativeCount++;
189:
190:         uint256 localTotalWeight = 0;
191:         for (uint256 i = 0; i < derivativeCount; i++)
192:             localTotalWeight += weights[i];
193:         totalWeight = localTotalWeight;
194:         emit DerivativeAdded(_contractAddress, _weight, derivativeCount);
195:     }

For instance, when adding the first derivative, the third parameter index to be passed to the DerivativeAdded event should be 0.

event DerivativeAdded(
    address indexed contractAddress,
    uint weight,
    uint index
);

When 188: derivativeCount++; is called before 194: emit DerivativeAdded(_contractAddress, _weight, derivativeCount);, the count is incremented and then index will be 1 instead of 0.

Patch

Increment derivativeCount after emitting event.

emit DerivativeAdded(_contractAddress, _weight, derivativeCount);
derivativeCount++;

============================================================================================================== # 2 ==============================================================================================================

Abstract

Avoid duplicated fragment of code when updating totalWeight

Same logic is repeated here https://github.com/code-423n4/2023-03-asymmetry/blob/main/contracts/SafEth/SafEth.sol#L170 and here https://github.com/code-423n4/2023-03-asymmetry/blob/main/contracts/SafEth/SafEth.sol#L170

Avoid duplicating code for better bugfixing and less prone to errors.

Patch

Create a private method _adjustWeight() called both by adjustWeight() and addDerivative()

File: contracts/SafEth/SafEth.sol
157:     /**
158:         @notice - Adds new derivative to the index fund
159:         @dev - Weights are only in regards to each other, total weight changes with this function
160:         @dev - If you want exact weights either do the math off chain or reset all existing derivates to the weights you want
161:         @dev - Weights are approximate as it will slowly change as people stake
162:         @param _derivativeIndex - index of the derivative you want to update the weight
163:         @param _weight - new weight for this derivative.
164:     */
165:     function adjustWeight(
166:         uint256 _derivativeIndex,
167:         uint256 _weight
168:     ) external onlyOwner {
169:         _adjustWeight(_derivativeIndex, _weight);
170:         emit WeightChange(_derivativeIndex, _weight);
171:     }
172:
173:     /**
174:         @notice - Adds new derivative to the index fund
175:         @dev - Weights are only in regards to each other, total weight changes with this function
176:         @dev - If you want exact weights either do the math off chain or reset all existing derivates to the weights you want
177:         @dev - Weights are approximate as it will slowly change as people stake
178:         @param _derivativeIndex - index of the derivative you want to update the weight
179:         @param _weight - new weight for this derivative.
180:     */
181:     function _adjustWeight(
182:         uint256 _derivativeIndex,
183:         uint256 _weight
184:     ) private onlyOwner {
185:         weights[_derivativeIndex] = _weight;
186:         uint256 localTotalWeight = 0;
187:         for (uint256 i = 0; i < derivativeCount; i++)
188:             localTotalWeight += weights[i];
189:         totalWeight = localTotalWeight;
190:     }
191:
192:     /**
193:         @notice - Adds new derivative to the index fund
194:         @param _contractAddress - Address of the derivative contract launched by AF
195:         @param _weight - new weight for this derivative.
196:     */
197:     function addDerivative(
198:         address _contractAddress,
199:         uint256 _weight
200:     ) external onlyOwner {
201:         uint256 _derivativeIndex = derivativeCount;
202:
203:         derivatives[_derivativeIndex] = IDerivative(_contractAddress);
204:         derivativeCount++;
205:         _adjustWeight(_derivativeIndex, _weight);
206:
207:         emit DerivativeAdded(_contractAddress, _weight, _derivativeIndex);
208:     }

Abstract

Assuming that the number of derivatives will always be lower than 256 (confirmed on Discord by @Toshi), you can save some gas by using uint8 instead of uint256 for derivativeCount in SafEthStorage.sol

Patch

In file contracts/SafEth/SafEthStorage.sol, from: 18: uint256 public derivativeCount; // amount of derivatives added to contract

to: 18: uint8 public derivativeCount; // amount of derivatives added to contract

You can find a git patch here, against "main" branch: https://pastebin.com/AiqnbfNZ with password "GqaLNmrB82"

Gas saved is then proportional to the number of derivatives set.

Tests

Results by running the tests.

Before: stake (min: 437702, max 660515, avg 527253) unstake (min: 418044, max 571044, avg 516303)

After: stake (min: 436099, max 658912, avg 525650) unstake (min: 416518, max 569256, avg 514514)