#!/bin/bash
#Todo: IPv6
#Todo: Other service types than gnudip (generic update URL)
#Todo: GET WAN IP from Router via UPnP if supported

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

#static values
EMPTYSTRING="none"
NOIP="0.0.0.0"
#how often do we poll for IP changes if we are behind a NAT?
UPDATEMINUTES=5
#if we do not have a IP check URL, how often should we do a "blind" update
UPDATEMINUTESUNKNOWN=3600
TOOLNAME=ez-ipupdate
UPDATE_TOOL=$(which ${TOOLNAME})

#Dirs and filenames
CFGDIR="/etc/${TOOLNAME}/"
CFG="${CFGDIR}${TOOLNAME}.conf"
CFG_disabled="${CFGDIR}${TOOLNAME}.inactive"
IPFILE="${CFGDIR}${TOOLNAME}.currentIP"
STATUSFILE="${CFGDIR}${TOOLNAME}.status"
LASTUPDATE="${CFGDIR}/last-update"
HELPERCFG="${CFGDIR}${TOOLNAME}-plinth.cfg"
CRONJOB="/etc/cron.d/${TOOLNAME}"

doReadCFG()
{ 
	host=""
	server=""
	user=""
	pass=""
	IPURL=""
	FILE=""
	[ -f $CFG_disabled ] && FILE=$CFG_disabled
	[ -f $CFG ] && FILE=$CFG

	if [ ! -z $FILE ];then
    	host=`cat $FILE 2> /dev/null |grep host |cut -d = -f 2`
	    server=`cat $FILE 2> /dev/null |grep server |cut -d = -f 2`
	    user=`cat $FILE 2> /dev/null |grep user |cut -d = -f 2 |cut -d : -f 1`
	    pass=`cat $FILE 2> /dev/null |grep user |cut -d = -f 2 |cut -d : -f 2`
	fi

	if [ ! -z $HELPERCFG ];then
		IPURL=`cat $HELPERCFG 2> /dev/null |grep URL |awk '{print $2}'`
	fi  
}

doGetOpt()
{
    while getopts ":s:d:u:p:I:" opt; do
        case $opt in
            s)
                server=$OPTARG
            ;;
            d)
                host=$OPTARG
            ;;
            u)
                user=$OPTARG
            ;;
            p)
                pass=$OPTARG
            ;;
            I)
            	if [ "$OPTARG" != "$EMPTYSTRING" ];then
                	IPURL=$OPTARG
            	else
    				IPURL=""	
    			fi
            ;;
            \?)
                echo "Invalid option: -$OPTARG" >&2
                exit 1
            ;;
            :)
                echo "Option -$OPTARG requires an argument." >&2
                exit 1
            ;;
        esac
    done
}

doWriteCFG()
{
	#always write to the inactive config - needs to be enabled vi "start" command later
	FILE=$CFG_disabled
	
	#reset the last update time
	echo 0 > $LASTUPDATE
	
	#reset the last updated IP
	echo "0.0.0.0" > $IPFILE
	
	#reset last update
	rm $STATUSFILE
	
	#find the interface (always the default gateway interface)
    DEFAULT=`ip route |grep default |awk '{print $5}'`
    
    #store the given options in ez-ipupdate compatible config file
    echo "host=$host" > $FILE
    echo "server=$server" >> $FILE
    echo "user=${user}:${pass}" >> $FILE
	echo "service-type=gnudip" >> $FILE
	echo "retrys=5" >> $FILE
	echo "execute=$0 success" >> $FILE
	echo "wildcard" >> $FILE
	
	#check if we are behind a NAT Router
    echo "IPURL $IPURL" > $HELPERCFG
    if [ -z $IPURL ];then
    	echo "NAT unknown" >> $HELPERCFG
	else 
		doGetWANIP
		ISGLOBAL=`ip addr ls $DEFAULT | grep $WANIP`
		if [ -z $ISGLOBAL ];then
			#we are behind NAT
			echo "NAT yes" >> $HELPERCFG
		else
			#we are directly connected
			echo "NAT no" >> $HELPERCFG
			#if this file is added ez-ipupdate will take ip form this interface
			echo "interface=$DEFAULT" >> $FILE
			#if this line is added to config file, ez-ipupdate will be launched on startup via init.d
			echo "daemon" >> $FILE
		fi
	fi
}

doGetWANIP()
{
	if [ $IPURL ];then
		OUTFILE=`mktemp`
		wget -4 -o /dev/null -O $OUTFILE $IPURL
		WANIP=`cat $OUTFILE`
		rm $OUTFILE
	else
		#no WAN IP found because of missing check URL
		WANIP=${NOIP}
	fi
	echo $WANIP > $IPFILE
}

cmd=$1
shift
case $cmd in
    configure)
        doGetOpt $@
        doWriteCFG
    ;;
    start)
        if [ "$(cat $HELPERCFG |grep ^NAT | awk '{print $2}')" = "no" ];then
        	mv $CFG_disabled $CFG
        	/etc/init.d/${TOOLNAME} start
    	else
    		echo "*/${UPDATEMINUTES} * * * * root $0 update" > $CRONJOB
    		$0 update
    	fi
    ;;
    get-nat)
    	NAT=`cat $HELPERCFG 2> /dev/null |grep ^NAT | awk '{print $2}'`
    	[ -z $NAT ] && NAT="unknown"
    	echo $NAT
    ;;
	update)
		doReadCFG
		OLDIP=`cat $IPFILE`
		doGetWANIP
		[ -f $CFG_disabled ] && FILE=$CFG_disabled
		[ -f $CFG ] && FILE=$CFG
		RESULT=0
		#if we know our WAN IP, only update if IP changes
		if [ "$OLDIP" != "$WANIP" -a "${WANIP}" != ${NOIP} ];then
			${UPDATE_TOOL} -c $FILE
			RESULT=$?
			cat /proc/uptime |awk '{print $1}' > $LASTUPDATE
		fi
		#if we don't know our WAN IP do a blind update once a hour
		if [ "${WANIP}" = ${NOIP} ];then
			UPTIME=`cat /proc/uptime`
			LAST=`cat $LASTUPDATE`
			DIFF=`expr $UPTIME - $LAST`  
			if [ $DIFF -gt $UPDATEMINUTESUNKNOWN ];then
				${UPDATE_TOOL} -c $FILE
				RESULT=$?
				cat /proc/uptime |awk '{print $1}' > $LASTUPDATE		
			fi
		fi 
		if [ $RESULT -eq 0 ];then
			$0 success
		else
			$0 failed
		fi
	;;
    stop)
        rm $CRONJOB 2> /dev/null
        /etc/init.d/${TOOLNAME} stop
        mv $CFG $CFG_disabled
    ;;
    success)
    	DATE=`date`
    	echo "last update done ($DATE)" > $STATUSFILE
    ;;
    failed)
    	DATE=`date`
    	echo "last update failed ($DATE)" > $STATUSFILE
    ;;    
    get-last-success)
    	if [ -f $STATUSFILE ];then
    		cat $STATUSFILE
    	else
    		echo "no update recorded since last config change"
    	fi
    ;;
    get-installed)
        if [ ! -z ${UPDATE_TOOL} ];then
            echo "installed"
        fi
    ;;
    status)
        doReadCFG
        PROC=`pgrep ${TOOLNAME}`
        if [ -f $CRONJOB ];then
             echo enabled 
        elif [ ! -z $PROC ];then 
        	echo enabled
    	else
            echo disabled
        fi
        echo $server
        echo $host
        echo $user
        echo $pass
        echo $IPURL
    ;;
    get-timer)
    	echo $UPDATEMINUTES
    ;;
    clean)
    	rm ${CFGDIR}/*
    ;;
    *)
        echo "usage: get-installed|status|configure <options>|start|stop|update|get-nat|clean|success|failed"
        echo ""
        echo "options are:"
        echo "-s <server>             Gnudip Server address"
        echo "-d <domain>             Domain to be updated"
        echo "-u <user>               Account username"
        echo "-p <password>           Account Password"
        echo "-I <IP check URL>       A URL which returns the IP of the client who is requesting"
        echo ""
		echo "update				  do a one time update"		
		echo "clean					  delete configuration"
		echo "success				  store update success"	
		echo "failed				  store update failure"		
    ;;
esac
exit 0