Implement eventing mechanism

[steven-bellock]

No description provided.

[steven-bellock]

@jyao1 should libspdm automatically insert the DMTF event type and the mandatory EventLost event into the SupportedEventGroupsList, or should it make the Integrator do that?

[steven-bellock]

Filed https://github.com/DMTF/SPDM-WG/issues/3739 to clarify how Requester should handle multiple SEND_EVENTs in the encapsulated flow.

[steven-bellock]

libspdm/include/library/spdm_requester_lib.h

Line 661 in 98ef964

libspdm_return_t libspdm_send_receive_encap_request(void *spdm_context, const uint32_t *session_id);

is the current public function to initiate encapsulated requests. However, there is no way to return an event list via such a function, so we'll need to figure that out.

I'm thinking of a function that returns after ENCAPSULATED_RESPONSE_ACK is received. If ENCAPSULATED_REQUEST.EncapsulatedRequest has data for the Integrator, such as SEND_EVENT.EventsList, then it will be placed into an Integrator-provided buffer. If the Responder has populated ENCAPSULATED_RESPONSE_ACK.EncapsulatedRequest then that field is stored in the scratch buffer and the Integrator is made aware that there is another request from the Responder. The Integrator can then decide whether it wants to continue the encapsulated flow or end the flow by sending an error message to the Responder, assuming https://github.com/DMTF/SPDM-WG/issues/3739 is clarified.

[steven-bellock]

From the 16-Dec-2024 meeting

• See how this would look with a callback function that the Requester-Integrator registers for event handling.
• See how an event storm from the Responder is handed.
  • In particular, Requester wants to ACK the SEND_EVENT but it does not want to (temporarily) service more SEND_EVENTs.
• Allow Integrator to specify an ERROR response to a SEND_EVENT.

[steven-bellock]

See how this would look with a callback function that the Requester-Integrator registers for event handling.

typedef libspdm_return_t(*libspdm_process_event_func)(void *spdm_context,
                                                      uint32_t session_id,
                                                      uint32_t event_count,
                                                      void *event_list,
                                                      size_t event_list_size);

void libspdm_register_event_handler(void *spdm_context, libspdm_process_event_func process_event);

It looks like the callback function should work fine, and can be used by both Requester and Responder.

I am not sure what the Event Receiver should do if it gets a bad SEND_EVENT message. I filed https://github.com/DMTF/SPDM-WG/issues/3932 to clarify the issue.

[steven-bellock]

I am not sure what the Event Receiver should do if it gets a bad SEND_EVENT message. I filed https://github.com/DMTF/SPDM-WG/issues/3932 to clarify the issue.

Consensus was that Receiving Endpoint will return an error to the Notifying Endpoint. Integrator should be aware of this so they can terminate the session.

[steven-bellock]

For the encapsulated flow the Requester sequence would be

1. libspdm_register_event_handler
2. Establish session, subscribe to events, etc.
3. libspdm_send_receive_encap_request
4. If Responder sends SEND_EVENT then libspdm performs as much validation as it can and then calls libspdm_process_event_func.
5. Integrator processes the events and returns error or success to libspdm.