CFT: IPv6 DNS autoconfiguration (RFC6106 RDNSS and DNSSL)

[J.R. Oldroyd]

Folks,

I have implemented IPv6 DNS autoconfiguration using the method described
in RFC6106 which describes RDNSS and DNSSL options on ICMPv6 router advertisements.

This implementation involves:
	- updates to rtadvd to send RDDNS and DNSSL options
	- updates to rtsold to receive these options

Then, to allow existing dhclient and the new rtsold to update the
/etc/resolv.conf file together, I have also created a new command:

	- /sbin/resolvconf - a script to manage resolv.conf updates
and:
	- /sbin/dhclient-script patches to use /sbin/resolvconf

Use of resolvconf to update /etc/resolv.conf allows simultaneous use
of dhclient for IPv4 DHCP and rtsold for IPv6 SLAAC.

At the moment, the diffs and new scripts are on this web page:

    http://opal.com/jr/freebsd/rdnss/

You'll have to grab the diffs and new scripts and apply and install
by hand.

In this work, I referenced an initial implementation of this for
OpenBSD (and sent feedback to that developer) as well as other work
such as the dns/openresolv port and MC's radns client.  The web page
explains why I developed alternatives.  The OpenBSD implementation
of the RDNSS and DNSSL options in rtadvd has some differences in
rtadvd.conf parsing; I may add similar functionality to this version
soon.  See the web page for details.

Feel free to give it all a try and send feedback.

	-jr