getifaddrs ipv6 support

[izissise]

Hello,

I'm trying to write a program with cosmo to connect to ip6 link-local hosts (fe80::...).

Using link-local ip6 usually involve known the interface scope-id so I wanted to use getifaddrs
to get them, but getifaddrs only returns ipv4 interface information.

So I tried to implement it but sadly ioctl(SIOCGIFCONF) only returns AF_INET information on linux.
Linux man page says this

AF_INET6 IPv6 addresses can be read from /proc/net/if_inet6 or via rtnetlink(7)

Surely it is not compatible with others OSes.

Openbsd seems to returns ipv6 information with ioctl(SIOCGIFCONF), see https://man.openbsd.org/netintro.4#ADDRESSING
Apple has an implementation for windows https://github.com/apple-oss-distributions/mDNSResponder/blob/71e6611203d57c78b26fd505d98cb57a33d00880/mDNSWindows/mDNSWin32.c#L3534
I could also found that parses /proc/net/if_inet6 on linux https://android.googlesource.com/platform/external/mdnsresponder/+/20faaf7/mDNSPosix/mDNSUNP.c#83

What do you think would be the best approach for this problem?

Thanks,
Hugues