#!/bin/sh

set -e

. /usr/share/debconf/confmodule

db_input low resolvconf/linkify-resolvconf || :
db_go

db_get resolvconf/linkify-resolvconf

# No need to ask about creating a 'tail' file if we've already asked
# or if /etc/resolv.conf is already a symlink; this is only for initial
# install.
if [ "$RET" = true ] && db_fget resolvconf/link-tail-to-original seen \
&& [ "$RET" = false ] && ! [ -L /etc/resolv.conf ]
then
if ! grep -q nameserver /etc/resolv.conf 2>/dev/null \
|| grep -q '# Generated by NetworkManager' /etc/resolv.conf 2>/dev/null \
|| grep -Eq '^[[:space:]]*(iface[[:space:]]+.*[[:space:]]+inet6?[[:space:]]+dhcp|dns[-_]nameservers[[:space:]]+[0-9A-Fa-f.:[:space:]]+[[:space:]]*(#.*)?$)' /etc/network/interfaces 2>/dev/null
then
# Either the /etc/resolv.conf is empty, or we've found
# at least one indicator that it's dynamically managed
# in at least some circumstances (via ifupdown dhcp,
# ifupdown 'dns-nameserver' static rules, or NM). No point
# in importing the existing nameservers.
db_set resolvconf/link-tail-to-original false
fi

db_input low resolvconf/link-tail-to-original || :
fi
db_input medium resolvconf/downup-interfaces || :
db_go