icvpn/scripts/mdnstohosts

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#!/bin/ash
#
#
#==========================================================================
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#==========================================================================
#
# this script collects all mdns names and converts them to a file in /etc/hosts style
# This file can then be fed to a regular dns server
#
# This file should be executed frequently via cron
FILENAME=/tmp/mdns_hosts
TMP="/tmp"
# resolve the name chunksize hosts at the same time.
chunksize=15
scriptname=$(basename $0)
# where should the lockfile be kept?
LOCKDIR="$TMP/$scriptname"
# use this executable to resolve a host that was announced via mdns
RESOLVER="/usr/bin/avahi-resolve-host-name"
# set to -6 if you want to resolve IPv6 address
# -4 otherwise
RESOLVER_ARGS="-4"
# Path to xargs
XARGS="/usr/bin/xargs"
cleanup()
{
local exitcode
local i
exitcode=$1
rm -f ${host_tmp}
if [ ! $exitcode -eq 0 ]
then
echo "aborted due to error" >&2
fi
trap - 1 2 3 6 9 13 14 15
rm -f "${LOCKDIR}/PID"
rm -rf "${LOCKDIR}"
exit ${exitcode:-1}
}
trap 'cleanup 1' 1 2 3 6 9 13 14 15
# obtain lock
while ! ( $(mkdir ${LOCKDIR} 2>/dev/null) )
do
echo there is already an instance of $(basename $0) running as PID: $(cat "${LOCKDIR}/PID" 2>/dev/null)
sleep 1
done
# lock obtained
echo $$ > "${LOCKDIR}/PID"
host_tmp=$(mktemp ${TMP}/$scriptname.XXXXXX)
hostnames=$(avahi-browse -t -p _workstation._tcp|cut -d\; -f4|cut -d\\ -f1|sort -u|awk '{print $1 ".local"}')
echo $hostnames | $XARGS -n $chunksize $RESOLVER $RESOLVER_ARGS 2>/dev/null |awk '{print $2 " " $1}' >"${host_tmp}"
mv "${host_tmp}" "${FILENAME}"
killall -SIGHUP dnsmasq
cleanup 0