#!/bin/bash
# updateip - very simple script for dyndns.org
# copyright (C) 2004 jc@jcomeau.com
# GPL licensed, see http://www.gnu.org/licenses/gpl.txt
# if script disables cronjob, simply delete /tmp/updateip.disabled
#  and it will be restarted
# but only AFTER fixing whatever the problem is!
# read www.dyndns.org/developers/ stuff to understand everything
# if more than one host, separate with commas: "www.bim.bo,www.dis.dat"
# make sure to make a root cronjob like this:
# * * * * * run-parts /etc/cron.constantly
USERNAME=$1
PASSWORD=$2
FQDN=$3
TESTING=$4
URL=http://members.dyndns.org/nic/update
CACHE=/tmp/updateip/last_known.txt
TMPCACHE=/tmp/updateip/current.txt
CRONJOB=/etc/cron.constantly/updateip
# add any more dyndns domains you need to the following list
DYNDNS_DOMAINS="dyndns.org kicks-ass.net dynalias.org isa-geek.com"
DISABLED=/tmp/updateip.disabled
MINUTE=60 # seconds
DAY=86400 # seconds
FORCE= # only force after 30 days (after 35, zone deleted by dyndns.org)
#TESTING="true" # comment this out, it can always be enabled from commandline
function loaduserinfo {
 [ "$USERNAME" ] && return
 USERNAME=`awk '$2 ~ "members.dyndns.org" {print $4}' $HOME/.netrc`
 PASSWORD=`awk '$2 ~ "members.dyndns.org" {print $6}' $HOME/.netrc`
}
function die {
 [ "$@" ] && echo "$@" >&2
 exit 1
}
[ -w / ] || die "Must be root"
mkdir -p $(dirname $CACHE) || die "Cannot create $(dirname $CACHE)"
mkdir -p $(dirname $CRONJOB) || die "Cannot create $(dirname $CRONJOB)"
loaduserinfo
[ "$TESTING" ] && echo USERNAME=$USERNAME
function loadfqdn {
 [ "$FQDN" ] && return
 for domain in $DYNDNS_DOMAINS; do
  fqdn=`awk "\\$2 ~ \"$domain$\" {print \\$2}" $HOME/.netrc`
  for host in $fqdn; do
   if [ "$host" != "members.dyndns.org" ]; then
    if [ "$FQDN" ]; then
     FQDN="$FQDN,$host"
    else
     FQDN=$host
    fi
   fi
  done
 done
}
loadfqdn
if [ "$TESTING" ]; then echo FQDN=$FQDN; fi
function log () {
 logger $@
}
function error () {
 echo $@ >&2
}
function logerror () {
 log -ist updateip $@
}
if [ -z "$USERNAME" -o -z "$PASSWORD" -o -z "$FQDN" ]; then
 error "Usage: $0 USERNAME PASSWORD FQDN [TESTMODE]"
 exit
fi
if [ -f $CRONJOB ]; then
 if [ -f $DISABLED ]; then
  logerror "Cron job has been disabled watch for bad return code!"
  if [ "$0" == "$CRONJOB" ]; then exit 1; fi
 fi
fi
if [ ! -f $CRONJOB -o $0 -nt $CRONJOB ]; then
 # can't use ln because this might be a softlink
 if cp -f $0 $CRONJOB; then
  logerror "NOTE: cron job has been created for this: $CRONJOB"
 else
  logerror "Failed creating cron job, exiting"
  exit 1
 fi
fi
lastrun=`python -c "import os; print os.stat(\"$TMPCACHE\")[8]"`
lastupdate=`python -c "import os; print os.stat(\"$CACHE\")[8]"`
thisrun=`date +%s`
if [ $((thisrun - lastupdate)) -gt $((29 * DAY)) ]; then FORCE=1; fi
[ "$TESTING" ] && echo "thisrun=$thisrun, lastrun=$lastrun"
delta=$((thisrun - lastrun))
if [ $delta -lt $((10 * MINUTE)) ]; then
 if [ "$0" == "$CRONJOB" ]; then
  # no need to log this 9 out of 10 runs is there?
  #logerror "Cannot run less than 10 minutes from previous run"
  exit
 else
  error "Should not run less than 10 minutes from previous run"
  error "Giving you 3 seconds to abort, hit control-C"
  sleep 3
 fi
fi
CURRENTIP=`lynx --dump http://checkip.dyndns.org:8245 \
 | awk '/Current IP Address: / {print $4}'`
if [ -z "$CURRENTIP" ]; then
 logerror Could not determine current IP
 exit 1
fi
echo $CURRENTIP > $TMPCACHE # cache it
[ "$TESTING" ] && error CURRENTIP=$CURRENTIP
LASTIP=`cat $CACHE`
if [ -z "$LASTIP" -o "$FORCE" ]; then
 logerror Last known IP "$LASTIP": skipping this run
 echo 0.0.0.0 > $CACHE
 if [ "$FORCE" ]; then echo 255.255.255.255 > $CACHE; fi
 exit
fi
[ "$TESTING" ] && error LASTIP=$LASTIP
# build the string that we'll need to compare with what DYNDNS returns
good="good $CURRENTIP"
count=`echo $FQDN | grep -c ','`
while [ "$count" != "0" ]; do
 good=`printf "%s\n%s" "$good" "good $CURRENTIP"`
 count=$((count - 1))
done
[ "$TESTING" ] && error "expecting: $good"
if [ "$CURRENTIP" != "$LASTIP" ]; then
 RETURNCODE=`lynx -auth $USERNAME:$PASSWORD -dump \
   "$URL?system=dyndns&hostname=$FQDN&myip=$CURRENTIP"`
 [ "$TESTING" ] && error "received: $RETURNCODE"
 if [ "$LASTIP" == "255.255.255.255" ]; then # means forced update
  logerror "Forced update of IP after 30 days; return code $RETURNCODE"
  echo $CURRENTIP > $CACHE
 elif [ "$RETURNCODE" != "$good" ]; then
  logerror "Bad return code from DYNDNS.ORG: $RETURNCODE; updates disabled"
  echo $RETURNCODE > $DISABLED
  logerror "Updating IP cache anyway: check before restarting!"
  echo $CURRENTIP > $CACHE
 else
  # good return, so cache the new IP
  echo $CURRENTIP > $CACHE
 fi
else
 if [ "$TESTING" ]; then
  error "IPs are the same, skipping update"
 fi
fi