Feature request: ipv6 support

[huyz-git]

Is your feature request related to a problem? Please describe. Currently linux-wifi-hotspot only support create ipv4 only AP through NAT. It would be nice if it could also support create dual stack AP.

Describe the solution you'd like Create an ipv6 AP has two different method, depends on what ipv6 address that the host machine have:

• If host machine only has a single ipv6 ( e.g. /128 by DHCPv6 or single /64 with suffix by SLAAC ), then the AP has no choice but using NAT6. It can use private ipv6 address like fc00::/7 for NAT6, or use 2001:db8::/32 if client wants to prefer ipv6 over ipv4.
• If host machine has an public ipv6 prefix ( e.g. whole /64 block ), then the AP can use prefix delegation to assign public ipv6 directly to client.

Describe alternatives you've considered For the first method, I haven't find any existing AP tools that supports NAT6. For the second method, NetworkManager's AP and a forked create_ap (https://github.com/dlenski/create_ap) supports prefix delegation.

Additional context

[86dd]

If the host has a /64 on-link via SLAAC you could use NDP proxying. For example Android uses this. 2001:db8::/32 is a documentation prefix and shouldn't be used. Also, please only use fd00::/8. fc00::/8 is for future global allocations. It would also be good if IPv6 is implemented to rename IPv4 stuff from IP to IPv4, so it is clear that the legacy version is meant.