Not sure about nameserver.sh name and scope yet so try to
hide it under a link. We can always change the name later
although having .sh suffix helps us lint the script more easily.
Routes only get added in system_resolvconf_generate() now where
the DNS override is properly checked. The nameservers are added
through the new script for convenience and removed from there as
well. As a bonus we still scrub the routes from the nameserver
file removal to avoid creating "state" about what was done elsewhere.
This is still subject to a lot of funky races for overlapping host
routes either by ISP, manual DNS, gateway monitors or static routes.
This was refactored previously and all the logic should live outside
dhclient-script but it seems it's only loosely handled over there.
For now put a check back in the old way and rework this later correctly
from the system.inc point of view: we do want to register nameserver
and searchdomain in the cache files, but should not add a route if
those are not required. It would be helpful to show them in the overview
regardless (as for DNS servers) but with a hint that they are not being
used.
PR: https://forum.opnsense.org/index.php?topic=26765.0
Moral of the story: don't try to call backend scripts to grab env
variables that you could easily read using the acual nameserver
script sort of like dhclient-script is doing it.
ALLOWOVERRIDE is silly as we guard against that in get_nameservers().
o Only operate the /var/db IP files via rc.newwanip(v6)
o Consistenly flush a cache IP on a triggered reload
o Remove IPv6 address removal workaround from https://redmine.pfsense.org/issues/2627
o Assume that IP is properly checked making $cacheip != $ip a valid assumption when $cacheip is empty
o Remove creation from dhclient script
".ext" came to be because dhclient-script from BSD is also under sbin/,
but since we always explicity use this one just move it to a neutral
location and point to it.
