[FSUG-Bangalore] GNU ifconfig & IPv6

[Debarshi Ray]

I am looking for a portable way to read the IPv6 address of a network
interface when its name is given. This is mainly needed to add some
functionality to GNU ifconfig [1] and while looking around came across
the USAGI FAQ [2], which says that SIOCGIFADDR does not work with IPv6
although it does for IPv4. Therefore variants of programs like this
[3] do not work for IPv6. I also found that the variant of ifconfig
provided by net-tools [4] parses files within /proc/net to read the
information instead of using ioctl commands. Another option seems to
be to use SIOCGIFCONF, to read all the available interfaces in a
linked list [5].

Now both these options seem problematic to me. Firstly /proc/net/ does
not seem to exist on GNU/Hurd [6] and NetBSD [7], while I do not want
to read all the interfaces when all I want is the IPv6 address of a
specific interface.

What do you suggest?

Thanks,
Debarshi

[1] http://www.gnu.org/software/inetutils
[2] http://www.linux-ipv6.org/faq.html
[3] http://rishi.fedorapeople.org/gnu/getip.c
[4] http://www.tazenda.demon.co.uk/phil/net-tools/
[5] http://www.ibm.com/developerworks/aix/library/au-ioctl-socket.html
[6] flubber.bddebian.com
[7] freeshell.org