Clarification about proxy forward

[dev-andreavendrame]

Good afternoon. We were studying the implementation of the repository and reading the code we have found a point that we don't uderstand.

In the implementation of the AlastriaIdentityManager.sol there is this a line of code that calls the PublicKeyRegistry function addKey. We have understood the overall process, but we don't understand how it is possible for the forward to call the specific "addKey" function.

The function signature is the following function addKey(string memory publicKey) so we need to pass a string as a parameter. The forward is called into the following function of AlastriaIdentityManager

function createAlastriaIdentity(bytes memory addPublicKeyCallData) public validAddress(msg.sender) isPendingAndOnTime(msg.sender) { AlastriaProxy identity = new AlastriaProxy(); identityKeys[msg.sender] = address(identity); pendingIDs[msg.sender] = 0; identity.forward(address(alastriaPublicKeyRegistry), 0, addPublicKeyCallData);//must be alastria registry call }

So our question is: what are we effectively passing with the parameter bytes memory addPublicKeyCallData and what does the 0 mean in the call identity.forward(address(alastriaPublicKeyRegistry), 0, addPublicKeyCallData)? Is the 0 a selector for the first function in the smart contract declaration?

Can you provide us a concrete example of what we are passing as the function parameter value?

Thanks in advance,

Andrea Vendrame.

[irzinfante]

The identity.forward(address(alastriaPublicKeyRegistry), 0, addPublicKeyCallData) instruction refers to this part of the AlastriaProxy.sol contract:

function forward(
    address destination,
    uint256 value,
    bytes memory data
) public onlyOwner returns(bytes memory) {
    (bool ret, bytes memory result) = destination.call.value(value)(data);
    require(ret);
    emit Forwarded(destination, value, data, result);
    return result;
}

Paying attention to the official documentation of Solidity v0.5.17 when doing a call to an address the .value(x) tells the amount of ETHs you are sending (in this case 0 ETH) an then the data, that is, addPublicKeyCallData in this case, the encoding of the method signature and the inputs for the method.

[dev-andreavendrame]

Thanks for your help! Have a good day,

Andrea.