Connext contest - GalloDaSballo's results

Handle

GalloDaSballo

Vulnerability details

Impact

Instead of creating a new array,

        uint256[] memory updated = new uint256[](newLength);

and then looping

You can iterate in place, saving gas

Example code, and tests in repo link given below

Proof of Concept

Provide direct links to all referenced code in GitHub. Add screenshots, logs, or any other relevant proof that illustrates the concept.

I rewrote the function as such:

    function remove(address user, uint256 preparedBlock) public {
        uint256 index = 99999999999999999999;
        uint256[] storage list = activeTransactionBlocks[user];
        uint256 length = list.length;
        
        for(uint256 x; x < length; x++){
          if(list[x] == preparedBlock){
            index = x;
          }
        }
    
        if(index != 99999999999999999999) {
          list[index] = list[list.length - 1];
          list.pop();
        }
    }

Current Version: Min 16635 · Max 64060 · Avg 35224

New Version: Min 16652 · Max 50306 · Avg 28333

Tools Used

You can run the repo with demo code here: https://github.com/GalloDaSballo/connext-gas

Also see "SO example on deleting element from array" https://ethereum.stackexchange.com/a/98484