Add zeroconf/mdns discovery

[balloob]

Discovery is currently stubbed out. Home Assistant is discoverable on _home-assistant._tcp.local.

[RussNelson]

If it's stubbed out, then why does it say that it's attempting to scan? This is confusing as heck.

[marciogranzotto]

I made a preliminary implementation of mdns search. But I still need to structure it a little better before opening a PR

[marciogranzotto]

Question about mdns.
When I find a mDNS record on my network, this is what android returns me:

BonjourService{flags=2, domain='local.', regType='_home-assistant._tcp.', serviceName='Home', dnsRecords={base_url=https://RETRACTED.duckdns.org, version=0.102.3, requires_api_password=true}, ifIndex=9, hostname='Home._home-assistant._tcp.local.', port=8123}
192.168.1.133

The thing is, using my duckdns external URL, I'm remapping the port to 1220, so if I would use that URL with the port that mDNS returns, it wouldn't work.
If I use the discovered IP address, and the port, it will work. But I have no way to know if ssl is required or not...

Should I just assume that http://IPADDRESS:PORT works?

[balloob]

You should update your config to make sure that your base url includes the port that you use.

We should initially try to connect to the base url.

If that won't work, we can do the http://IPADDRESS:PORT but it means we need to disable SSL verification in case the user uses Let's Encrypt (hence why we should use the base url)

[marciogranzotto]

If the base URL fails, I can also check if starts with https and use that with the IP address

[balloob]

@marciogranzotto have you made progress on your implementation ?