webrtc: resolve domains in webrtcAdditionalHosts on server-side

[aler9]

Describe the feature

Domains in webrtcAdditionalHosts and consequently in SDPs are causing troubles:

• they have limited support (not existent in Firefox / Safari).
• they cause strange behaviors in case of IPv6 (an IPv4 is needed anyway otherwise resolution fails, furthermore IPv6 is used only when IPv6 internet is working).
• they need of a custom version of pion/webrtc

The situation can be improved by solving domains on server-side, and sending resolved IPs to clients.

[Sunvas]

What if domain has only IPv6 (AAAA record) and not IPv4 (no A record)?

[aler9]

@Sunvas the server will convert an IPv6-only domain into an IPv6, send the IP to clients and the connection will work.

Currently Chrome fails resolving these domains with error -105.

[github-actions]

This issue is mentioned in release v1.14.0 🚀
Check out the entire changelog by clicking here