#!/bin/sh

IFNAME=$1
IPADDR=$4
OLDIPADDR=0.0.0.0
OLDIPFILE=/etc/ppp/dynamic_old_ip.tmp

HOSTNAME=`hostname`
DNSCONF=/etc/dnsmasq.conf
DNSZONE=`grep ^domain= ${DNSCONF} | cut -f 2 -d =`
DNSSERV=ns.${DNSZONE}

NSUPDATE=/usr/bin/nsupdate
KEYFILE=/etc/${DNSZONE}.private

if [ -r ${OLDIPFILE} ]; then
  OLDIPADDR=`cat ${OLDIPFILE}`
else
  OLDIPADDR=0.0.0.0
fi

if [ ${OLDIPADDR} == ${IPADDR} ]; then
  exit 1;
fi

${NSUPDATE} -k ${KEYFILE} << EOF
server ${DNSSERV}
zone ${DNSZONE}
update delete ${HOSTNAME}.${DNSZONE}.
update add ${HOSTNAME}.${DNSZONE}. 60 IN A ${IPADDR}
show
send
EOF

rm -f ${OLDIPFILE}
echo ${IPADDR} >${OLDIPFILE}