script to update records on a powerdns server when called by isc-dhcpd

dnsupdate.sh

#!/bin/bash

# arguments are type, address, hardware, name

LOGFILE=/tmp/dns.log
SUFFIX=".clients.example.com."

APIKEY="SUPERsecretAPIkey"
APIPORT=8081
APIADDRESS="10.0.0.1"
APIENDPOINT="/api/v1/servers/localhost/zones/example.com."
PTRENDPOINT="/api/v1/servers/localhost/zones/10.10.10.in-addr.arpa."

TYPE=$1
ADDRESS=$2
MAC=$3
HOSTNAME="$4"

if [ "$HOSTNAME" == "none" ]
then
        HOSTNAME="dhcp-${ADDRESS}"
fi

case $TYPE in
        "commit")
                ### commit a new lease to the API
                FQDN="${HOSTNAME}${SUFFIX}"
                echo "adding entry ${FQDN}"

                JSON=$( cat << END
{ "rrsets": [
        {
                "name": "${FQDN}",
                "type": "A",
                "ttl": 86400,
                "changetype": "REPLACE",
                "records": [
                {
                        "content": "$ADDRESS",
                        "disabled": false,
                        "set-ptr": true
                }]
        }
]}
END
)

                curl -H "X-API-Key: ${APIKEY}" -X PATCH --data "$JSON" http://${APIADDRESS}:${APIPORT}${APIENDPOINT}
                ;;

        "release"|"expire")
                echo "removing entry ${ADDRESS}"
                ### remove a dns entry
                
                # look up the entry name via its PTR record
                # piping through xargs strips the spaces :D
                PTRNAME=$(nslookup $ADDRESS $APIADDRESS | grep name | cut -d'=' -f2 | xargs)

                # verify that PTRNAME is vaguely valid
                if [ "$PTRNAME" == " " ] ; then
                        # no result found, we probably shouldn't try to process it further
                        echo "PTR not found"
                        exit 1
                fi              
                
                # sanity check on the length of PTRNAME to avoid deleting the entire
                if [ $(echo "$PTRNAME" | wc -c) -lt 2 ] ; then
                        # name is too short
                        echo "name $PTRNAME too short"
                        exit 1
                fi

                ### remove the A record
                echo "ptr name is $PTRNAME"
                JSON=$( cat << END
{ "rrsets": [
        {
                "name": "$PTRNAME",
                "type": "A",
                "changetype": "DELETE"
        }
]}
END
)
                echo $JSON | json
                curl -H "X-API-Key: ${APIKEY}" -X PATCH --data "$JSON" http://$APIADDRESS:$APIPORT$APIENDPOINT

                ### remove the PTR record
                PTRID="$(printf '%s.' $ADDRESS | tac -s.)in-addr.arpa."
                JSON=$( cat << END
{ "rrsets": [
        {
                "name": "$PTRID",
                "type": "PTR",
                "changetype": "DELETE"
        }
]}
END
)
                echo $JSON | json
                curl -H "X-API-Key: ${APIKEY}" -X PATCH --data "$JSON" http://$APIADDRESS:$APIPORT$PTRENDPOINT
                ;;
esac

echo "`date` ${TYPE} $ADDRESS $MAC $HOSTNAME" | tee -a $LOGFILE