#!/bin/sh
#
# Name:         dyndnsup
# Description:  Auto-update dynamic dns service
# Version:      1.0
# Author:       Jose V Beneyto, <joberui@eui.upv.es>
# Depends on:   netcat

# checkid:
checkid() {
        user_id=`id -u`
        if [ "$user_id" != "0" ]
        then
                echo "you need to be root for running this script!" >&2
                exit 1
        fi
}
# checkdepends: check dependecies
checkdepends() {
        for dep in netcat
        do
                which $dep >& /dev/null
                if [ $? == 1 ]
                then
                        echo "$dep not found, please install it!" >&2
                        exit 1
                fi
        done
}
# readconfig:
readconfig() {
        if [ -f $CONFIG_FILE ]
        then
                . $CONFIG_FILE
                [ "$DYNDNS_SERVER" == "" ] && {echo "DYNDNS_SERVER variable not set!" >&2; exit 1}
                [ "$DYNDNS_PROTOCOL" == "" ] && {echo "DYNDNS_PROTOCOL variable not set!" >&2; exit 1}
                [ "$DYNDNS_HOSTNAME" == "" ] && {echo "DYNDNS_HOSTNAME variable not set!" >&2; exit 1}
                [ "$DYNDNS_IF" == "" ] && {echo "DYNDNS_IF variable not set!" >&2; exit 1}
        fi
}
# chech time:
checktime(){
        if [ ! -f $CACHE_FILE ]
        then
                TIME_EXPIRED="yes" # force update
        else
                last_mod_date=`date +'%y%m%d' -r $CACHE_FILE`
                #last_mod_time=`date +'%H%M%S' -r $CACHE_FILE`
                current_date=`date +'%y%m%d'`
                #current_time=`date +'%H%M%S'`

                # check if timer has expired
                days_since_last_mod=`expr $current_date - $last_mod_date`
                if [ "$days_since_last_mod" -lt "$MAX_TIME" ]
                then
                        TIME_EXPIRED="no"
                else
                        TIME_EXPIRED="yes"
                fi
        fi
}
# checkip:
checkip() {
        current_ip=`ifconfig $DYNDNS_IF | grep 'inet addr' | awk '{print $2}' | sed -e 's/.*://'`
        if [ ! -f $CACHE_FILE ]
        then
                echo "ip=$current_ip" > $CACHE_FILE
                last_ip="" # force update
        else
                last_ip=`cat $CACHE_FILE | grep 'ip' | sed 's/ip=//g'`
        fi
        if [ "$last_ip" == "$current_ip" ]
        then
                echo "can't update, ip not changed!" >&2
                exit 1
        else
                DYNDNS_IP=$current_ip
        fi
}
# update:
update() {
        DYNDNS_IP=$1
        echo -ne "GET /nic/update?system=$DYNDNS_PROTOCOL&hostname=$DYNDNS_HOSTNAME&myip=$DYNDNS_IP" | netcat -vv $SERVER_DYNDNS 80
}

# cache file
CACHE_FILE="/var/cache/dyndnsup.cache"
# config file
# (you can edit this file to overwrite script variables)
CONFIG_FILE="/etc/dyndnsup.conf"
# script variables
# (CONFIG_FILE overwrite them)
MAX_TIME="20" # (days)
DYNDNS_SERVER="members.dyndns.org"
DYNDNS_PROTOCOL="dyndns2"
DYNDNS_HOSTNAME="mikeux.dyndns.org"
DYNDNS_IP=""
DYNDNS_IF="eth0"

checkid
checkdepends
readconfig
checktime
checkip
[ "$TIME_EXPIRED" == "yes" ] && echo "update!"
#update
echo "DYNDNS_SERVER=$DYNDNS_SERVER"
echo "DYNDNS_PROTOCOL=$DYNDNS_PROTOCOL"
echo "DYNDNS_HOSTNAME=$DYNDNS_HOSTNAME"
echo "DYNDNS_IP=$DYNDNS_IP"
echo "DYNDNS_IF=$DYNDNS_IF"
echo ""


exit 0

# End of File