content_changed implementation about libspdm HOT 4 OPEN

The Integrator needs to monitor request_attribute and the SignatureRequested bit, since content_change can only be asserted when a signature is requested. So it keeps track of measurements when SignatureRequested is not set, and does a comparison when SignatureRequested is set.

from libspdm.

Thanks and I think that works for normal scenario. But as "Any communication between Requester and Responder other than a GET_MEASUREMENTS request or response re-initializes L1/L2 computation to null .", the integrator seems not able to know if L1/L2 has been re-inited?

from libspdm.

Yes, that looks like it's an issue. The state of the l1/l2 transcript is stored in the spdm_context but it is currently not public. We would need to provide a public function to query the transcript state. @jyao1 does that sound good?

from libspdm.

I feel a callback function to notify L1/L2 was reset might be easier for integrators to track the measurement.
Maybe provide a callback function for transcript state change (similar to connection state callback)?

from libspdm.