tree ca9753d5e0bbbb29c19b7ec8657f7e66003da206
parent ef48506891d28b2ffeab32be7776836b76726534
author Thu Nguyen <thu@os.amperecomputing.com> 1690169987 +0700
committer Andrew Jeffery <andrew@aj.id.au> 1690863459 +0930

transport: free un-wanted responses in pldm_transport_send_recv_msg()

mctp-demux broadcasts the PLDM response messages to all of mctp
socket instances. That means the GetSensorReading response from one
instance (pldmd) can be received by the other instance (pldmtool)
which is waiting for the response of GetPDR request message. When the
gap time between the two requests of pldmtool is long enough the
number of GetSensorReading response messages can be more than 32. That
means the instance ID of new GetPDR command in pldmtool can equal with
the used and free one in GetSensorReading. The
`pldm_transport_send_recv_msg()` will detect the reponse of
GetSensorReading as the response of the GetPDR request.

To prevent this unexpected behavior the `pldm_transport_send_recv_msg()`
should free the un-wanted responses before sending new PLDM request. The
serialised message to be sent must already encode an allocated instance
ID, which by the specification must not be reused before expiry.
Therefore after the socket is drained, any subsequent response
containing the request's instance ID must be the response matching the
request.

Signed-off-by: Thu Nguyen <thu@os.amperecomputing.com>
[AJ: Add a test, massage the commit message]
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I6c684bdaea2ba5d96b24ecd3c72e846c644fb16d