bmx6

h1. Mdns: mesh DNS system

This is an example of bmx6 SMS plugin utilization. It is a distributed DNS system where every node publish the domains it is managing.

The current implementation is done for working in OpenWRT with the Dnsmasq daemon.

h3. Usage

* /etc/init.d/mdns start -> starts the system (adds itself to the crontab)

* /etc/init.d/mdns stop -> stops the system (removes itself from crontab)

* /etc/init.d/mdns reload -> update the data

h3. Files

* /etc/mdns/public contains the list of domains we wanto to announce in the network

* /etc/mdns/hosts contains a list of "IP -> domain" which have been obtained from the network (dnsmasq looks on it)

h3. Executation

By default, even if there are not domains to publish in /etc/mdns/public file, the mdns script publish its own hostname.[ALL_ACCEPTED_TLDs]

The accepted TLDs can be configured in the variables DOMAINS4 and DOMAINS6, for IPv4 and IPv6 respectivelly. 

So if someone publish "google.com" but your mdns instance is not accepting the ".com" TLD it will be discarted.

<pre>

root@UPClab104-1677:~# /etc/init.d/mdns start

-> preparing bmx6

INFO  uci_create_section: bmx6.cfg125cb5=syncSms

INFO  uci_save_option: bmx6.cfg125cb5.syncSms=mdns

INFO  uci_save_option: bmx6.cfg125cb5.syncSms=mdns

INFO  : --syncSms                 mdns                          

-> adding addn-host entry to dnsmasq config file

-> restarting dnsmasq daemon

-> cleaning files

-> publishing own IPv4 domains: UPClab104-1677.qmp

-> publishing own IPv6 domains: UPClab104-1677.qm6

-> added remote domains google.qmp pau.qmp tita.qmp SApalafolls-ebb2.qmp = 10.228.206.65

-> added remote domains SApalafolls-ebb2.qm6 = 2012:0:0:ebb2::1

root@UPClab104-1677:~# ping google.qmp

PING google.qmp (10.228.206.65): 56 data bytes

64 bytes from 10.228.206.65: seq=0 ttl=63 time=25.248 ms

64 bytes from 10.228.206.65: seq=1 ttl=64 time=1.655 ms

64 bytes from 10.228.206.65: seq=2 ttl=64 time=1.661 ms

64 bytes from 10.228.206.65: seq=3 ttl=64 time=1.692 ms

64 bytes from 10.228.206.65: seq=4 ttl=64 time=1.593 ms

^C

--- google.qmp ping statistics ---

5 packets transmitted, 5 packets received, 0% packet loss

round-trip min/avg/max = 1.593/6.369/25.248 ms

root@UPClab104-1677:~# ping SApalafolls-ebb2.qm6

PING SApalafolls-ebb2.qm6 (2012:0:0:ebb2::1): 56 data bytes

64 bytes from 2012:0:0:ebb2::1: seq=0 ttl=64 time=1.886 ms

64 bytes from 2012:0:0:ebb2::1: seq=1 ttl=64 time=1.632 ms

64 bytes from 2012:0:0:ebb2::1: seq=2 ttl=64 time=1.679 ms

64 bytes from 2012:0:0:ebb2::1: seq=3 ttl=64 time=1.801 ms

^C

--- SApalafolls-ebb2.qm6 ping statistics ---

4 packets transmitted, 4 packets received, 0% packet loss

round-trip min/avg/max = 1.632/1.749/1.886 ms

</pre>

h3. Code

<pre>

#!/bin/sh

#    Copyright (C) 2013 Pau Escrich <p4u@dabax.net>

#

#    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 program is distributed in the hope that it will be useful,

#    but WITHOUT ANY WARRANTY; without even the implied warranty of

#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

#    GNU General Public License for more details.

#

#    You should have received a copy of the GNU General Public License along

#    with this program; if not, write to the Free Software Foundation, Inc.,

#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

#

#    The full GNU General Public License is included in this distribution in

#    the file called "COPYING".

# Configuration variables                                     

MDNS_DIR="/etc/mdns"                                                

HOSTF="$MDNS_DIR/hosts"                                            

MY_DOMAINS="$MDNS_DIR/public"                                     

DOMAINS4="qmp"

DOMAINS6="qm6"

SMSF="/var/run/bmx6/sms/sendSms/mdns"                                       

SMSR="/var/run/bmx6/sms/rcvdSms"                                            

DNSMASQ="/etc/dnsmasq.conf"                                     

DNSMASQ_PID="/var/run/dnsmasq.pid"

# Optional

IPV4=""

IPV6=""

start() {

	if ! cat /etc/crontabs/root | grep mdns > /dev/null; then

		echo "/10 * * * * /etc/init.d/mdns reload > /tmp/log/mdns.log" >> /etc/crontabs/root

		/etc/init.d/cron enable

		/etc/init.d/cron start

	fi

	/etc/init.d/mdns reload

	}

stop() {

	sed -i -e '/.*\/etc\/init\.d\/mdns reload > \/tmp\/log\/mdns\.log$/d' /etc/crontabs/root

	/etc/init.d/cron restart

	}

reload() {

	init

	publish_my_domains

	get_domains

	finish	

}

refresh() { 

	reload

}

# Code

error() {

	echo "ERROR: $@"

	exit 1

}

log() {

	echo -e "-> $@"

}

init() {

	log "preparing bmx6"

	bmx6 -c --syncSms mdns

	[ $? -ne 0 ] && error "cannot configure bmx6 daemon"

	cat $DNSMASQ | egrep "^addn-hosts=$HOSTF" -q || {

		log "adding addn-host entry to dnsmasq config file"

		echo "addn-hosts=$HOSTF" >> $DNSMASQ

		log "restarting dnsmasq daemon"

		/etc/init.d/dnsmasq restart

	}

	ps | grep dnsmasq -q || error "dnsmasq not running"

	log "cleaning files"

	[ -f $SMSF ] && rm -f $SMSF

	touch $SMSF

	[ -f $HOSTF ] && rm -f $HOSTF

	touch $HOSTF	

	[ ! -d $MDNS_DIR ] && mkdir -p $MDNS_DIR

	touch $MY_DOMAINS

}

check_domain() {

		local v="$1"

		local d="$2"

		local valid=1

		local domains=""

		[ $v == "4" ] && domains="$DOMAINS4"

		[ $v == "6" ] && domains="$DOMAINS6"

		[ $v == "all" ] && domains="$DOMAINS4 $DOMAINS6"

		for D in $domains; do

			echo "$d" | egrep "\.$D"$ -q && valid=0 && break

		done 

		return $valid

}

get_my_domains() {

	local v=${1:-4}

	local my_domains=""

	local domains=""

	local d

	for d in $(cat $MY_DOMAINS); do

		check_domain $v $d && my_domains="$d $my_domains"

	done

	[ "$v" == "4" ] && domains="$DOMAINS4"

	[ "$v" == "6" ] && domains="$DOMAINS6"

	for d in $domains; do

		my_domains="$(cat /proc/sys/kernel/hostname).$d $my_domains"

	done

	echo $my_domains

}

get_my_ip4() {

	[ -z $IPV4 ] && \

	bmx6 -cp | grep tun4Address | awk '{print $2}' | awk -F / '{print $1}' || \

	echo "$IPV4"

}

get_my_ip6() {

	[ -z $IPV4 ] && \

	bmx6 -cp | grep tun6Address | awk '{print $2}' | awk -F / '{print $1}' || \

	echo "$IPV6"

}

publish_my_domains() {

	local d domains

	local ip4="$(get_my_ip4)"

	local ip6="$(get_my_ip6)"

	[ -z "$ip4$ip6" ] && error "cannot get ip address"

	[ -n "$ip4" ] && {

		domains="$(get_my_domains 4)"

		log "publishing own IPv4 domains: $domains"

		echo "$ip4 $domains" >> $SMSF

		echo "$ip4 $domains" >> $HOSTF

	}

	[ -n "$ip6" ] && {

		domains="$(get_my_domains 6)"

		log "publishing own IPv6 domains: $domains"

		echo "$ip6 $domains" >> $SMSF

		echo "$ip6 $domains" >> $HOSTF

	}

}

get_domains() {

	local f d domline ip line n i

	ls $SMSR/*:mdns 2>/dev/null >/dev/null && {

	  # for each received file	

	  for f in $SMSR/*:mdns; do

		n=$(cat $f | wc -l)

		# for each line inside the file

		for i in $(seq $n); do

			line=$(cat $f | awk "NR==$i")

			ip="$(echo $line | awk '{print $1}')"

			[ -z $ip ] && continue

			domains=""

			# for each domain (first is IP)

			for d in $(echo "$line" | awk '{$1=""; print $0}'); do

				check_domain all $d && domains="$d $domains"

			done

			[ -n "$domains" ] && echo "$ip $domains" >> $HOSTF

			log "added remote domains $domains= $ip"

	  done

  done 

	  } || log "not published domains found in the network"

}

finish() {

	kill -SIGHUP $(cat $DNSMASQ_PID)

}

$@

</pre>