Remove clear_multicast_endpoints() in unsubscribe.

[akhzarj]

Author: Aram Khzarjyan [email protected], MBition GmbH.

Remove clear_multicast_endpoints() in unsubscribe. #651

The clearing multicast endpoints stops any multicast messages
receiving without recovering if TTLs are not expiring.

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The program was tested solely for our own use cases, which might differ from yours.

The submission is provided under the main project license (LICENSE file in root of project).

Provider Information

[gunnar-mb]

PR looks good to me.

[duartenfonseca]

Hi @akhzarj could you give an example of how we can reproduce this issue?

[duartenfonseca]

if one wants to unsubscribe to a set of service/instance, why would you want to receive any more messages from that specific endpoint?

[akhzarj]

Yes in your case that true.
Meanwhile in our case just one unsubscribe stops other events to receive.
If I remember correctly it was impacting also other services that was using the same multicast group address.

[duartenfonseca]

@akhzarj i am trying to reproduce one your issue. i am using the attached config files.
vsomeip-udp-client.json
vsomeip-udp-service.json

1. my client subscribes initially to both 0x4465 and 0x4555.
2. then I unsubscribe to 0x4555.
3. my client still receives notifications from 0x4465.
   would this be reproducing it correctly?

thanks

[akhzarj]

Hi @duartenfonseca
One small but essential difference is the TTL value that is 3 in your configs.
That allows to recover the multicast endpoint.
If you will put max value like 0xFFFFFF (see https://www.autosar.org/fileadmin/standards/R22-11/FO/AUTOSAR_PRS_SOMEIPServiceDiscoveryProtocol.pdf#subsubsection.5.1.2.5 PRS_SOMEIPSD_00356])
Then it will not recover until next reboot.
And as I have mentioned in previews comment: #651 (comment)
It could stop receiving events for multiple clients/apps if they are using common service/multicast endpoint as well.

[duartenfonseca]

@akhzarj do you have any pcap logs of the behaviour? because even with the TTL 0xFFFFF it does not happen. When using the subscribe-sample/notify-sample, the new offer always restores the endpoint so it does not stay closed.
here is the pcap:
remove_multicast_endpoint.zip

[duartenfonseca]

on the logs we still see the messages being received on the client, for the other event which was not unsubscribed

[akhzarj]

Hi @duartenfonseca
Yes if the new offer message is sent, then definitely it will be recovered.
And new offer could be sent in some specific conditions (TTL expair, Repetition phase, etc) SomeIP SD
In case when no offer sent then no recovery happens. That issue we had faced.
If needed I can try to setup example that it will reproduced the issue.

[duartenfonseca]

@akhzarj an example would be helpful, thank you!