fix(mavftp): don't use cache for other sys/comp ids

[alexcekay]

Solved Problem

When having two different mavftp clients (not parallel, this would cause a lot of problems anyway), it is possible that the resend logic will not send a reply to client B as it confuses it with client A.

This can happen in the following case:

Client A -> req (seq: 0) -> FMU
FMU -> repl -> Client A

<some time pass>

Client B -> req (seq: 0) -> FMU
No reply from FMU as payload->seq_number + 1 == last_payload->seq_number,
so nothing is sent to this client.

Especially if the retry of Client B is not implemented smart and it starts a new mavftp_client in those cases it will always start with seq 0 again and will get the same error over and over.

Solution

• Do not use the cache when the request comes from a different sys/comp id

Alternatives

• Clients should implement robust retries in any case. This is an additional robustness measure.

Test coverage

• Tested on the bench with a v6n

[bkueng]

Good find