[lwip-devel] Q. should mdns be announcing an ip4 address of 0.0.0.0?

[Douglas]

Hi,

Working on the mdns responder, and noticed that it sends out ipv4
packets before the interface has an ipv4 address, so sends them out with
a source address of 0.0.0.0 and announces an A record with address 0.0.0.0.

This is when using dhcp to obtain the ipv4 address, so the interface can
be up and ipv6 can be operational and announced even before ipv4.

Every time the connection drops and reconnects it goes thought this
announcement. Given that UDP is not reliable, might this be mdns less
reliable.

Would anyone know if this is the correct behaviour.

A. Should the mdns responder announce to an ipv4 broadcast address
before the interface has an ipv4 address? If not then it could still
announce to the ipv6 broadcast address before it has an ipv4 address.

B. Should the mdns responder announce an A record of 0.0.0.0 before it
has an ipv4 address? Might this flush out the address in case it
changes, or would it be better to just skip announcing this A record
until the address is obtained?

Douglas