#!/bin/sh
# Copyright (c) 2007-2011 Roy Marples
# All rights reserved

# libc subscriber for 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.

SYSCONFDIR=@SYSCONFDIR@
LIBEXECDIR=@LIBEXECDIR@
VARDIR=@VARDIR@
IFACEDIR="$VARDIR/interfaces"
NL="
"

# 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
}

# Support original resolvconf configuration layout
# as well as the openresolv config file
if [ -f "$SYSCONFDIR"/resolvconf.conf ]; then
	. "$SYSCONFDIR"/resolvconf.conf
elif [ -d "$SYSCONFDIR"/resolvconf ]; then
	SYSCONFDIR="$SYSCONFDIR/resolvconf/resolv.conf.d"
	base="$SYSCONFDIR/resolv.conf.d/base"
	if [ -f "$base" ]; then
		name_servers="$(key_get_value "nameserver " "$base")"
		search_domains="$(key_get_value "search " "$base")"
		if [ -z "$search_domains" ]; then
			search_domains="$(key_get_value "domain " "$base")"
		fi
		resolv_conf_options="$(key_get_value "options " "$base")"
	fi
	if [ -f "$SYSCONFDIR"/resolv.conf.d/head ]; then
		resolv_conf_head="$(cat "${SYSCONFDIR}"/resolv.conf.d/head)"
	fi
	if [ -f "$SYSCONFDIR"/resolv.conf.d/tail ]; then
		resolv_conf_tail="$(cat "$SYSCONFDIR"/resolv.conf.d/tail)"
	fi
fi
: ${resolv_conf:=/etc/resolv.conf}
: ${libc_service:=nscd}
: ${libc_restart:=@RESTARTCMD ${libc_service}@}
: ${list_resolv:=@PREFIX@/sbin/resolvconf -l}
if [ "${resolv_conf_head-x}" = x -a -f "$SYSCONFDIR"/resolv.conf.head ]; then
	resolv_conf_head="$(cat "${SYSCONFDIR}"/resolv.conf.head)"
fi
if [ "${resolv_conf_tail-x}" = x -a -f "$SYSCONFDIR"/resolv.conf.tail ]; then
	resolv_conf_tail="$(cat "$SYSCONFDIR"/resolv.conf.tail)"
fi

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

case "${resolv_conf_passthrough:-NO}" in
[Yy][Ee][Ss]|[Tt][Rr][Uu][Ee]|[Oo][Nn]|1)
	newest=
	for conf in "$IFACEDIR"/*; do
		if [ -z "$newest" -o "$conf" -nt "$newest" ]; then
			newest="$conf"
		fi
	done
	[ -z "$newest" ] && exit 0
	newconf="$(cat "$newest")$NL"
	;;
*)
	[ -z "$RESOLVCONF" ] && eval "$(@PREFIX@/sbin/resolvconf -v)"
	newsearch="$(uniqify $search_domains $SEARCH $search_domains_append)"
	NS="$LOCALNAMESERVERS $NAMESERVERS"
	newns="$(uniqify $name_servers $NS $name_servers_append)"

	# Hold our new resolv.conf in a variable to save on temporary files
	newconf="# Generated by resolvconf$NL"
	if [ -n "$resolv_conf_head" ]; then
		newconf="$newconf$resolv_conf_head$NL"
	fi
	[ -n "$newsearch" ] && newconf="${newconf}search $newsearch$NL"
	for n in $newns; do
		newconf="${newconf}nameserver $n$NL"
	done

	# Now get any configured options
	opts="$resolv_conf_options${resolv_conf_options:+ }"
	opts="$opts$($list_resolv | key_get_value "options ")"
	if [ -n "$opts" ]; then
		newconf="${newconf}options"
		for opt in $(uniqify $opts); do
			newconf="${newconf} $opt"
		done
		newconf="$newconf$NL"
	fi

	if [ -n "$resolv_conf_tail" ]; then
		newconf="$newconf$resolv_conf_tail$NL"
	fi
	;;
esac

# Check if the file has actually changed or not
if [ -e "$resolv_conf" ]; then
	[ "$(cat "$resolv_conf")" = "$(printf %s "$newconf")" ] && exit 0
fi

# Create our resolv.conf now
(umask 022; printf %s "$newconf" >"$resolv_conf")
eval $libc_restart

retval=0
# Notify users of the resolver
for script in "$LIBEXECDIR"/libc.d/*; do
	if [ -f "$script" ]; then
		if [ -x "$script" ]; then
			"$script" "$@"
		else
			(. "$script")
		fi
		retval=$(($retval + $?))
	fi
done
exit $retval