Handling Unrecoverable Errors

[siddharthteli12]

According to the Luna documentation. when a fatal / unrecoverable error occurs we must logout, close the session, finalise & then re-initialise the PKCS#11 library. Do we have standard pattern for retry after a fatal error or helper method something like is_fatal so we could reinitialise manually? My current idea is whenever a fatal error occurs, drop the current session and PKCS#11 context ? Is this pattern safe and idiomatic, or could it cause issues?

use cryptoki::{context::Pkcs11, session::Session};
use tokio::sync::RwLock;
use thiserror::Error;

#[derive(Error, Debug)]
pub enum LunaError {
    #[error("Not initialized")]
    UnInit,
}

struct Luna {
    session: RwLock<Option<Session>>,
    pk: RwLock<Option<Pkcs11>>,
}

impl Luna {
    pub async fn unrecoverable_error(&self) -> Result<(), LunaError> {
        // Assuming init() has already been called.
        // Dropping the session and PKCS would trigger logout, close, and finalize.
        self.session.write().await.take();
        self.pk.write().await.take();

        // Will reinitialize again after this.
        Ok(())
    }
}

[hug-dev]

Hello!

Do we have standard pattern for retry after a fatal error or helper method something like is_fatal so we could reinitialise manually?

Not at the moment! I guess the definition of a critical/fatal error is dependent on the implementation of the PKCS11 API. So maybe something that should be done on the user's side of this library?

My current idea is whenever a fatal error occurs, drop the current session and PKCS#11 context ? Is this pattern safe and idiomatic, or could it cause issues?

I think it seems reasonable. With #326 you will be able to explicitly call close/finalize on your session/Pkcs11 struct. The only thing I am not sure about is the async bit, since I am not too familiar with async programming. But there could be a function which is mapped on a cryptoki::error:Result and would check, in case of error, if it's critical and then do what you showed here.