net: mdns: missing rfc6732 unicast features

[SynchronicIT]

In the current mDNS implementation, all responses are sent to the multicast address. Independent of its source, unicast-response bit or one of the other cases mentioned in RFC 6732.
Chapter 5.1, 5.4, 6.7 and introduction of chapter 6, derive different use-cases and when to use the unicast responses.

Unicast responses would allow lightweight clients or clients who do not have multicast access (read: docker images) to discover zephyr hosts and their services.

Changes to be made a in mdns_responder.c to send_response(..) which currently always creates a multicast destination address, but to follow the rules as specified by rfc6732.
The first low hanging fruit would be to support the legacy or one-shot requests, by responding over unicast if the source port is not 5353.

[jukkar]

@SynchronicIT thanks for the report. You seem to have investigated this already in sources, are you able / do you plan to send PR for this?

[SynchronicIT]

Hi I made a quick fix which checks the source port. I want to extend it and clean up and then provide a PR.

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@SynchronicIT <https://github.com/SynchronicIT> thanks for the report. You seem to have investigated this already in sources, are you able / do you plan to send PR for this? — Reply to this email directly, view it on GitHub <#81657 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BDJ3H2WKSG3SYBPVRSVPXST2BXKMNAVCNFSM6AAAAABSERXWZWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDIOJRGA4DEMRZGI> . You are receiving this because you were mentioned.Message ID: ***@***.***>