twice.md

Description

The functions receivePacket() and _processMessageFromRoot() allow receiving the same packetId_ multiple times.

Steps to reproduce

Expected behavior

I would have expected that if a value exists, it can't be overwritten. If the current behaviour is considered a feature then if would be good to add a comment.

Actual behavior

The functions receivePacket() and _processMessageFromRoot() allow receiving the same packetId_ multiple times. If the same packetId_ is send twice then packetIdToRoot[packetId_] is overwritten. Normally the second value for root_ would be the same as the previous, but if problems would occur elsewhere this might not be the case.

Screenshots

Additional information

NativeSwitchboardBase.sol#L210-L216:

function receivePacket(...) ... {    
    packetIdToRoot[packetId_] = root_; // no check if a value is already present
    ...
}

PolygonL2Switchboard.sol#L112-L123:

function _processMessageFromRoot(...) ... {    
    (bytes32 packetId, bytes32 root) = abi.decode(
        data_,
        (bytes32, bytes32)
    );
    packetIdToRoot[packetId] = root; // no check if a value is already present
    ...
}