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

# dnsmasq 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.

[ -f "/etc"/resolvconf.conf ] || exit 0
. "/etc/resolvconf.conf" || exit 1
[ -z "${dnsmasq_conf}" -o -z "${dnsmasq_resolv}" ] && exit 0
eval "$(${RESOLVCONF:-resolvconf} -v)"

PREFIX=
DNSMASQ="${DNSMASQ:-/usr/sbin/dnsmasq}"
DBUS_SEND="${DBUS_SEND:-/usr/bin/dbus-send}"
dnsmasqpid="${dnsmasq_pid:-/var/run/dnsmasq.pid}"

newconf="# Generated by resolvconf\n"
newresolv="${newconf}"

# Using dbus means that we never have to restart the daemon
# This is important as it means we should not drop DNS queries
# whilst changing DNS options around. However, dbus support is optional
# so we need to validate a few things first.
# Check for DBus support in the binary

dbus=false
dbuspid="${dbus_pid:-/var/run/messagebus.pid}"
if [ -x "$DNSMASQ" -a -x "$DBUS_SEND" -a -s "${dbuspid}" -a -s "${dnsmasqpid}" ]; then
	if "$DNSMASQ" --version 2>/dev/null | \
		grep -q "^Compile time options.*[[:space:]]DBus[[:space:]]"
	then
		# Sanity - check that dnsmasq and dbus are running
		if kill -0 "$(cat "${dbuspid}")" 2>/dev/null && \
			kill -0 "$(cat ${dnsmasqpid})" 2>/dev/null
		then
			dbus=true
			newconf="${newconf}\n# Domain specific servers will"
			newconf="${newconf} be sent over dbus\nenable-dbus\n"
		fi
	fi
fi

for n in ${NAMESERVERS}; do
	case "\n${newresolv}\n" in
	*"\nnameserver ${n}\n");;
	*) newresolv="${newresolv}nameserver ${n}\n";;
	esac
done

dbusdest=
for d in ${DOMAINS}; do
	dn="${d%%:*}"
	ns="${d#*:}"
	while [ -n "${ns}" ]; do
		if "${dbus}"; then
			SIFS="${IFS-y}" OIFS="$IFS"
			IFS=.
			set -- ${ns%%,*}
			num="0x$(printf "%02x" $1 $2 $3 $4)"
			if [ "${SIFS}" = "y" ]; then
				unset IFS
			else
				IFS="$OIFS"
			fi
			dbusdest="${dbusdest} uint32:$(printf "%u" ${num})"
			dbusdest="${dbusdest} string:${dn}"
		else
			newconf="${newconf}server=/${db}/${ns%%,*}\n"
		fi
		[ "${ns}" = "${ns#*,}" ] && break
		ns="${ns#*,}"
	done
done

changed=false
if [ ! -f "${dnsmasq_conf}" ] || \
	[ "$(cat "${dnsmasq_conf}")" != "$(printf "${newconf}")" ]
then
	changed=true
	printf "${newconf}" > "${dnsmasq_conf}"
fi
if [ -f "${dnsmasq_resolv}" ]; then
	if [ "$(cat "${dnsmasq_resolv}")" != "$(printf "${newresolv}")" ]; then
		changed=true
		printf "${newresolv}" > "${dnsmasq_resolv}"
	fi
else
	# dnsmasq polls this file so no need to set changed=true
	printf "${newresolv}" > "${dnsmasq_resolv}"
fi

"${changed}" && resolvconf -s dnsmasq reload
if "${dbus}"; then
	# Send even if empty so old servers are cleared
	"$DBUS_SEND" --system --dest=uk.org.thekelleys.dnsmasq \
 		/uk/org/thekelleys/dnsmasq uk.org.thekelleys.SetServers \
  		${dbusdest}
fi
