Thanks. How would you feel about the following potential configuration design?
* Add a new configuration option "send_mdns_unicast"
* When true, use the current behavior
* When false, send the query on all non-loopback non-p2p interfaces
* Have send_mdns_unicast default to false
I was thinking through how to pick interfaces, looked up what other mDNS libraries do, and pretty much all of them don't allow configuring interfaces, whereas Avahi exposes allow-interfaces and deny-interfaces. I'm leaning towards not making this configurable to reduce complexity. I think that anyone interested in that level of config is probably using Avahi anyway.
Additionally this design has two nice properties: the default behavior is RFC-compliant, and it means that for my use-case I don't need to change the config file, which was a big part of my motivation for doing this inside of musl in the first place :-)
David