Appending questions to MDNS responses breaks Avahi-Daemon (IDFGH-5736)

[d8ahazard]

This is to loop in this library on the discussion being had here:

Aircoookie/WLED#2009 (comment)

and here:

avahi/avahi#348

Basically, the esp-mdns implementation is echoing th question message in responses, which causes avahi-daemon to discard the response as invalid.

I can see this happening here at line 1085:

https://github.com/espressif/esp-idf/blob/master/components/mdns/mdns.c

Apparently, the proper approach as per the RFC for MDNS is to ignore these responses, so it would stand to reason that the behavior on this side is fine, but I just wanted to link it to the other issues for completeness.

[negativekelvin]

#7124

[david-cermak]

@negativekelvin Thanks for the reference

@d8ahazard This bug was fixed as

• f601cb0 on v4.4
• 3a588d7 on v4.3
• 93921e0 on v4.2

Please update the IDF version to include the above commits. It's also possible to work around this bug setting

• CONFIG_MDNS_STRICT_MODE to y

[david-cermak]

@d8ahazard Could you please close the issue?

[Alvin1Zhang]

Thanks for reporting, feel free to reopen.