net/udpbroadcastrelay: IPv6 support

[chris-beedie]

Important notices
Before you add a new report, we ask you kindly to acknowledge the following:

[X] I have read the contributing guide lines at https://github.com/opnsense/plugins/blob/master/CONTRIBUTING.md

[X] I have searched the existing issues and I'm convinced that mine is new.

[X] When the request is meant for an existing plugin, I've added its name to the title.

OPNsense 21.7.5-amd64
os-udpbroadcastrelay 1.0_2

Is your feature request related to a problem? Please describe.
Netflix on android is not able to discover newer chromecast generations (at least gen3 and gen4. gen1 is ok, gen2 untested) as they use IPv6 mDNS. Other apps (e.g. youtube) are ok on all chromecasts.

Describe the solution you'd like
udp broadcast relay to support ipv6 mDNS.

Describe alternatives you've considered
I've tried blocking and rejecting ipv6 udp traffic to force netflix/chromecast to fallback to ipv4, but it didn't work.

Additional context
Add any other context or screenshots about the feature request here.

[marjohn56]

I'll not be adding v6 support as I don't have time, but the source is available for forking if anyone wants to do so.

[fichtner]

@marjohn56 is this about the port instead of plugin?

[mimugmail]

If it's only plugin I can take it.

[marjohn56]

It's likely to be both. Certainly the port needs to be checked too.

[chris-beedie]

I've done some digging. It looks like the port would need updated too. There is an issue on udp-redux/udp-broadcast-relay-redux#18 which looks to be a fork from the same original code. It mentions the need for AF_INET6 sockets which don't appear in the opnsense port either.

I'm happy to help if I can, but I'm not familiar with FreeBSD development and my C and networking knowledge is rough at best.

[OPNsense-bot]

This issue has been automatically timed-out (after 180 days of inactivity).

For more information about the policies for this repository,
please read https://github.com/opnsense/plugins/blob/master/CONTRIBUTING.md for further details.

If someone wants to step up and work on this issue,
just let us know, so we can reopen the issue and assign an owner to it.