libcoap-rs 0.2.2

// SPDX-License-Identifier: BSD-2-Clause
/*
 * event.rs - Event handling traits and logic for the libcoap Rust Wrapper.
 * This file is part of the libcoap-rs crate, see the README and LICENSE files for
 * more information and terms of use.
 * Copyright © 2021-2023 The NAMIB Project Developers, all rights reserved.
 * See the README as well as the LICENSE file for more information.
 */

//! Event handling-related code

use std::fmt::Debug;

use libcoap_sys::{coap_event_t, coap_session_get_context, coap_session_t};

use crate::context::CoapContext;
use crate::session::CoapSession;

use crate::session::CoapServerSession;

/// Trait for CoAP event handlers.
///
/// Implementations of this trait can be provided to a [CoapContext] to handle various events relating
/// to sessions.
///
/// This is the equivalent to the [libcoap `coap_event_handler_t` type](https://libcoap.net/doc/reference/develop/group__events.html#ga5d57fba7df54eae6f8cb3a47a4cb3569).
pub trait CoapEventHandler: Debug {
    /// Handle a DTLS connected event.
    ///
    /// This event is triggered when a DTLS session switches to the connected state.
    #[allow(unused_variables)]
    fn handle_dtls_connected(&mut self, session: &mut CoapSession) {}

    /// Handle a DTLS closed event.
    ///
    /// This event is triggered when a DTLS session is closed.
    #[allow(unused_variables)]
    fn handle_dtls_closed(&mut self, session: &mut CoapSession) {}

    /// Handle a DTLS renegotiation event.
    ///
    /// This event is triggered when a DTLS renegotiation occurs.
    #[allow(unused_variables)]
    fn handle_dtls_renegotiate(&mut self, session: &mut CoapSession) {}

    /// Handle a DTLS error event.
    ///
    /// This event is triggered when a DTLS error occurs.
    #[allow(unused_variables)]
    fn handle_dtls_error(&mut self, session: &mut CoapSession) {}

    /// Handle a TCP connected event.
    ///
    /// This event is triggered when a new TCP connection is established.
    #[allow(unused_variables)]
    fn handle_tcp_connected(&mut self, session: &mut CoapSession) {}

    /// Handle a TCP closed event.
    ///
    /// This event is triggered when a new TCP connection is closed.
    #[allow(unused_variables)]
    fn handle_tcp_closed(&mut self, session: &mut CoapSession) {}

    /// Handle a TCP failed event.
    #[allow(unused_variables)]
    fn handle_tcp_failed(&mut self, session: &mut CoapSession) {}

    /// Handle a session connected event.
    ///
    /// This event is triggered by CSM exchanges only when reliable protocols are used.
    #[allow(unused_variables)]
    fn handle_session_connected(&mut self, session: &mut CoapSession) {}

    /// Handle a session closed event.
    ///
    /// This event is triggered by CSM exchanges only when reliable protocols are used.
    #[allow(unused_variables)]
    fn handle_session_closed(&mut self, session: &mut CoapSession) {}

    /// Handle a session failed event.
    ///
    /// This event is triggered by CSM exchanges only when reliable protocols are used.
    #[allow(unused_variables)]
    fn handle_session_failed(&mut self, session: &mut CoapSession) {}

    /// Handle a (Q-)Block receive error.
    #[allow(unused_variables)]
    fn handle_partial_block(&mut self, session: &mut CoapSession) {}

    /// Handle the creation of a new server-side session.
    ///
    /// This event is called inside of the IO loop when a new server-side session is created.
    #[allow(unused_variables)]
    fn handle_server_session_new(&mut self, session: &mut CoapServerSession) {}

    /// Handle the deletion of a server-side session.
    ///
    /// This event is called inside of the IO loop when a server-side session is deleted.
    /// This can happen for a number of reasons:
    /// - The session has been idle for too long (see [CoapContext::session_timeout()] and
    ///   [CoapContext::set_session_timeout()])
    /// - The maximum number of handshaking sessions is exceeded (see
    ///   [CoapContext::max_handshake_sessions()] and [CoapContext::set_max_handshake_sessions()])
    /// - The maximum number of idle sessions is exceeded (see
    ///   [CoapContext::max_idle_sessions()] and [CoapContext::set_max_idle_sessions()])
    #[allow(unused_variables)]
    fn handle_server_session_del(&mut self, session: &mut CoapServerSession) {}
}

// This should be fine as we don't provide this type to a FFI function, we only read from it.
#[allow(improper_ctypes_definitions)]
pub(crate) unsafe extern "C" fn event_handler_callback(raw_session: *mut coap_session_t, event: coap_event_t) -> i32 {
    let session: CoapSession = if event == coap_event_t::COAP_EVENT_SERVER_SESSION_NEW {
        CoapServerSession::initialize_raw(raw_session).into()
    } else {
        CoapSession::from_raw(raw_session)
    };
    // SAFETY: Pointer is always valid as long as there is no bug in libcoap.
    let context = CoapContext::from_raw(coap_session_get_context(raw_session));
    context.handle_event(session, event);
    0
}