net.tcp.dns.query doesn't support SRV records

[frater]

I wanted to monitor some SRV-records of a foreign SIP-provider and found out that the native function net.tcp.dns.query doesn't support them.
Creating a trigger that will give an alert also didn't work out because the answer is not always given in the same order when it resolves to more than 1 IP.

That's why I created this quick-and-dirty alternative where the output gets sorted and the first field where it repeats the DNS-name gets cut. I implemented that latest part because it enables me to create a trigger that does a comparison of 2 different domains.

UserParameter=net.dns.query[*],/usr/local/sbin/dnsquery "$1" "$2" "$3"
UserParameter=net.dns.query.cksum[*],/usr/local/sbin/dnsquery "$1" "$2" "$3" | md5sum | tr -cd 0-9 | cut -b1-10

SRV-record sip.dom1.com is not the same as sip.dom2.com
{Zabbix server:net.dns.query.cksum[, "_sip._udp.sip.dom1.com", "SRV"].last(0)}#{Zabbix server:net.dns.query.cksum[, "_sip._udp.sip.dom2.com", "SRV"].last(0)}

SRV-record sip.dom1.com has changed
{Zabbix server:net.dns.query[, "_sip._udp.sip.dom1.com", "SRV"].diff(0)}=1

#!/bin/bash
#####################################################
# dnsquery
#####################################################
#
# echo 'UserParameter=net.dns.query[*],/usr/local/sbin/dnsquery "$1" "$2" "$3"' >>/etc/zabbix/zabbix_agentd.conf
#
# echo 'UserParameter=net.dns.query.cksum[*],/usr/local/sbin/dnsquery "$1" "$2" "$3"' >>/etc/zabbix/zabbix_agentd.conf
#####################################################
export PATH=${PATH}:/usr/local/sbin:/sbin:/usr/sbin:/bin:/usr/bin

IP=$1
RAWZONE=$2
TYPE=$3
WAIT=4

[ -z "${RAWZONE}" ] && exit 1
ZONE="`echo "${RAWZONE}" | grep '\.' | grep '[A-Za-z0-9.-]*'`"
[ "${RAWZONE}" = "${ZONE}" ] || exit 1

if [ ! -z "${IP}" ] ; then
  if ! echo "${IP}" | grep -qE '^([0-9]{1,3}\.){3}[0-9]{1,3}$' ; then
    exit 1
  fi
fi

[ -z "$TYPE" ] && TYPE=A

ftmp1=`mktemp`
host -W${WAIT} -t${TYPE} ${ZONE} ${IP} 2>/dev/null >${ftmp1}
ERRNO=$?

[ $ERRNO -gt 1 ] && exit 1
if [ $ERRNO -eq 0 ] ; then
  sort ${ftmp1} | cut -d' ' -f2-
else
  cat ${ftmp1}
fi
rm -f ${ftmp1}