Re: [lwip-users] mDNS behaviour on IP address change

[Massimiliano Cialdi]

I apologize for thinking too suddenly about a bug.
Actually it was enough to set LWIP_NETIF_EXT_STATUS_CALLBACK to have
the expected behavior.
I apologize again.

best regards
Max


On Mon, Mar 14, 2022 at 3:49 PM massimiliano cialdi via lwip-users
<lwip-users@nongnu.org> wrote:
>
> continuing to read RFC 6762 at section 8.4
> (https://datatracker.ietf.org/doc/html/rfc6762#section-8.4) I find:
>
>
> At any time, if the rdata of any of a host's Multicast DNS records
> changes, the host MUST repeat the Announcing step described above to
> update neighboring caches.  For example, if any of a host's IP
> addresses change, it MUST re-announce those address records.
>
>
> This is exactly the case I was describing.
> I have tested both the 2.1.3 release of lwip and the current master. In
> both cases mDNS doesn't re-announce.
>
>
> I believe this can be considered a bug.
>
>
> best regards
>
> Max
>
>
>
> Massimiliano Cialdi
> FIRMWARE ENGINEERING PROFESSIONAL LEADER
>
> Powersoft S.p.A.
> Via E. Conti, 5 - Scandicci (Fi) 50018 - Italy
> OFFICE:    +39 055 7350230
>
>
>
>
>
>
> On 14/03/22 11:02, massimiliano cialdi wrote:
> >
> > hello,
> >
> > In RFC 6762 I find (section 8):
> >
> >
> > "Whenever a Multicast DNS responder starts up, wakes up from sleep,
> > receives an indication of a network interface "Link Change" event, or
> > has any other reason to believe that its network connectivity may
> > have changed in some relevant way, it MUST perform the two startup
> > steps below: Probing (Section 8.1) and Announcing (Section 8.3)."
> >
> >
> > Does the IP change fall under one of the reasons for reannouncement?
> > In my opinion it should but I'm not sure. I mean, if I set
> > LWIP_DHCP_AUTOIP_COOP and assigned a link-local address, and then a
> > dhcp server is turned on, my IP address changes. I believe that this
> > should require sending a new announcement to inform of the newly
> > acquired IP.
> >
> > Lwip doesn't seem to act like that, but I don't know if it should.
> > What do you guys think?
> >
> >
> > best regards
> >
> > Max
> >
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Oppugnatio solaris!
VIS!

Massimiliano Cialdi
cialdi@gmail.com