#!/bin/sh
# Copyright 2007-2009 Roy Marples
# All rights reserved

# libc subscriber for resolvconf
# You could symlink /etc/resolv.conf to resolvconf/run/resolv.conf
# for a read only etc, if resolvconf/run is linked to /var/run/resolvconf.

# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#     * Redistributions of source code must retain the above copyright
#       notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above
#       copyright notice, this list of conditions and the following
#       disclaimer in the documentation and/or other materials provided
#       with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# Load our variables from resolvconf
eval "$(resolvconf -v)"

RESOLVCONF=/etc/resolv.conf
PREFIX=@PREFIX@
SYSCONFDIR=@SYSCONFDIR@
LIBEXECDIR=@LIBEXECDIR@
BASE="${SYSCONFDIR}/resolv.conf.base"

uniqify()
{
    local result=
    while [ -n "$1" ]; do
		case " ${result} " in
		*" $1 "*);;
		*) result="${result} $1";;
		esac
		shift
	done
    echo "${result# *}"
}

# sed may not be available, and this is faster on small files
key_get_value()
{
	local key="$1" value= x= line=

	shift
	if [ $# -eq 0 ]; then
		while read line; do
			case "${line}" in
			"${key}"*) echo "${line##${key}}";;
			esac
		done
	else
		for x; do
			while read line; do
				case "${line}" in
				"${key}"*) echo "${line##${key}}";;
				esac
			done < "${x}"
		done
	fi
}

NEWNS=
NEWSEARCH=
if [ -e "${BASE}" ]; then
	NEWNS="$(key_get_value "nameserver " "${BASE}")"
	NEWSEARCH="$(key_get_value "search " "${BASE}")"
	if [ -z "${NEWSEARCH}" ]; then
		NEWSEARCH="$(key_get_value "domain " "${BASE}")"
	fi
fi
NEWSEARCH="$(uniqify ${NEWSEARCH} ${SEARCH})"
NEWNS="$(uniqify ${NEWNS} ${NAMESERVERS})"

# Hold our new resolv.conf in a variable to save on temporary files
NEWCONF=""
[ -e "${SYSCONFDIR}"/resolv.conf.head ] \
	&& NEWCONF="${NEWCONF}$(cat "${SYSCONFDIR}"/resolv.conf.head)\n"
[ -n "${NEWSEARCH}" ] && NEWCONF="${NEWCONF}search ${NEWSEARCH}\n"
for N in ${NEWNS}; do
	NEWCONF="${NEWCONF}nameserver ${N}\n"
done

# Now get any configured options
OPTS=
if [ -e "${BASE}" ]; then
	OPTS="$(key_get_value "options " "${BASE}")"
fi
OPTS="${OPTS}${OPTS:+ }$(resolvconf -l | key_get_value "options ")"
if [ -n "${OPTS}" ]; then
	NEWCONF="${NEWCONF}options"
	for OPT in $(uniqify ${OPTS}); do
		NEWCONF="${NEWCONF} ${OPT}"
	done
	NEWCONF="${NEWCONF}\n"
fi

[ -e "${SYSCONFDIR}"/resolv.conf.tail ] \
	&& NEWCONF="${NEWCONF}$(cat "${SYSCONFDIR}"/resolv.conf.tail)\n"

# Check if the file has actually changed or not
if [ -e "${RESOLVCONF}" ]; then
	[ "$(cat "${RESOLVCONF}")" = "$(printf "${NEWCONF}")" ] && exit 0
fi

# Create our resolv.conf now
(umask 022; printf "${NEWCONF}" > "${RESOLVCONF}")

resolvconf -s nscd restart
retval=$?

# Notify users of the resolver
for x in "${LIBEXECDIR}"/libc.d/*; do
	if [ -e "${x}" ]; then
		"${x}" "$@"
		retval=$((${retval} + $?))
	fi
done
exit ${retval}