Authorizer

Authorizer is the core module in Cobo Safe that is used to implement access controls.

All transactions sent by Delegates via execTransaction() must be approved by the Authorizer before execution.

An Authorizer has to implement the following interfaces:

interface IAuthorizer {
    function flag() external view returns (uint256 authFlags);

    function preExecCheck(TransactionData calldata transaction) external returns (AuthorizerReturnData memory authData);

    function postExecCheck(
        TransactionData calldata transaction,
        TransactionResult calldata callResult,
        AuthorizerReturnData calldata preAuthData
    ) external returns (AuthorizerReturnData memory authData);

    function preExecProcess(TransactionData calldata transaction) external;

    function postExecProcess(TransactionData calldata transaction, TransactionResult calldata callResult) external;
}

• preExecCheck: validate the transaction before it is executed (e.g., contract address, call method, parameters, ETH amount of the transaction)

• postExecCheck: validate the transaction and its outcomes after it has been executed (e.g., changes in wallet balance, leverage ratio in a DeFi protocol)

• preExecProcess: complete certain operations before the transaction is executed (e.g., recording the transaction amount)

• postExecProcess: complete certain operations after the transaction has been executed

• flag: the above four methods are not mandatory for an Authorizer; the Authorizer can indicate the specific functions that need to be executed by configuring flag

The following struct shows a transaction that is yet to be executed:

struct TransactionData {
    address from; // `msg.sender` who performs the transaction a.k.a wallet address.
    address delegate; // Delegate who calls executeTransactions().
    // Same as CallData
    uint256 flag; // 0x1 delegate call, 0x0 call.
    address to;
    uint256 value;
    bytes data; // calldata
    bytes hint;
    bytes extra;
}

• from: the msg.sender of the transaction (e.g. the from value for a Cobo Safe Account will be the contract address of Safe)

• delegate: the Delegate who sent the transaction; Authorizer will use this value to review whether the transaction is authorized

• All other fields have the same definition as that for CallData

postExecCheck has two additional parameters:

• TransactionResult: the status and output of a transaction after it has been executed

• AuthorizerReturnData:data returned by preExecCheck