[net_server] DHCP client doesn't add domain name to resolv.conf

[diver]

DHCP client built in net_server should support putting domain name to resolv.conf.
man resolv.conf

 search          Search list for host-name lookup.  The search list is nor-
                 mally determined from the local domain name; by default, it
                 contains only the local domain name.  This may be changed by
                 listing the desired domain search path following the search
                 keyword with spaces or tabs separating the names.  Most
                 resolver queries will be attempted using each component of
                 the search path in turn until a match is found.  Note that
                 this process may be slow and will generate a lot of network
                 traffic if the servers for the listed domains are not local,
                 and that queries will time out if no server is available for
                 one of the domains.

                 The search list is currently limited to six domains with a
                 total of 256 characters.

[diver]

This one is implemented in hrev35938.

[vegardw]

hrev35938 doesn't implement this completely though.

It implements DHCP option 15, which corresponds to the "domain" keyword in resolv.conf.

In addition to this the DCHP server can send a additional list of search domains using DHCP option 119 (RFC3397), which corresponds to the "search" keyword in resolv.conf. This is not implemented yet.

[stippi]

vegardw, do you want to have a go at it? I've fixed some possible regressions in follow up commits, and left a more verbose TODO comment in the code. Maybe you are interested? :-)

[vegardw]

Replying to stippi:

vegardw, do you want to have a go at it? I've fixed some possible regressions in follow up commits, and left a more verbose TODO comment in the code. Maybe you are interested? :-)

Sure, I could have a stab at it. I have one week Easter holidays starting this weekend, and need something to do that week :)

[korli]

see ​http://svnweb.freebsd.org/base?view=revision&revision=230597