dnstest

#!/bin/sh

PATH=/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin
export PATH

#
# Program: DNS Validation Test <dnstest>
#
# Author: Matty < matty91 at gmail dot com >
#
# Current Version: 1.0
#
# Revision History:
#
# Version 1.0
#     Original release
#
# Last Updated: 09-12-2016
#
# Purpose:
#   Pings one or more DNS servers to check DNS resolution and query latency.
#
# License:
#   This program is free software; you can redistribute it and/or modify it
#   under the terms of the GNU General Public License as published by the
#   Free Software Foundation; either version 2, or (at your option) any
#   later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#
# Example:
# $ dnstest -r prefetch.net -i 209.197.94.145 -r a -c 1 192.168.1.1 192.168.1.2
# Checking the health of DNS server 192.168.1.1:
#  *** Got the correct result for prefetch.net
#  *** prefetch.net resolved to 209.197.94.145
#  *** DNS latency resolving prefetch.net on 192.168.86.1 is 1 msec
# 
# Checking the health of DNS server 192.168.1.2:
#  *** Got the correct result for prefetch.net
#  *** prefetch.net resolved to 209.197.94.145
#  *** DNS latency resolving prefetch.net on 192.168.86.2 is 1 msec
# 

# DNS servers to contact (passed on command line)
DNSSERVERS="127.0.0.1"

# Run the lookup and latency tests this number of times to look for errors (-c iterations)
ITERATIONS=1

# Resource record to query (-r record_name)
RRECORD_NAME="prefetch.net"

# IP resource record should resolve to (-i record_ip)
RRECORD_IP="209.197.94.145"

# Resource record type to query (-r record_type)
RRECORD_TYPE="a"

# Amount of time to sleep between tests (-t X)
SLEEP_INTERVAL=0

latency() {
    dig @${1} ${2} ${RRECORD_TYPE} | awk '{ if ($0 ~/Query time/) print $4,$5}'
}

lookup() {
    dig +short @${1} $2 ${RRECORD_TYPE}
}

dnstest() {
    count=0
    while [ ${count} -lt ${ITERATIONS} ]; do
        # DNS server to check
        server=${1}

        echo "Checking the health of DNS server ${server}:"
        ip=$(lookup ${server} ${RRECORD_NAME})
        if [ "${ip}" = "${RRECORD_IP}" ]; then
            echo " *** Got the correct result for ${RRECORD_NAME}"
            echo " *** ${RRECORD_NAME} resolved to ${ip}"
        else
            echo -e "\033[33;7m*** Got a negative result for ${RRECORD_NAME}\033[0m"
            echo -e " *** ${RRECORD_NAME} resolved to ${ip}"
            echo -e " *** ${RRECORD_NAME} should resolve to ${RRECORD_IP}"
        fi
        dnslatency=$(latency ${server} ${RRECORD_NAME})
        echo " *** DNS latency resolving ${RRECORD_NAME} on ${server} is ${dnslatency}"
        echo ""
        count=$((count+1))
        sleep ${SLEEP_INTERVAL}
    done
}

parse() {
    while getopts c:d:i:r:s:t: option
    do
        case "${option}"
        in
            d) RRECORD_NAME=${OPTARG};;
            i) RRECORD_IP=${OPTARG};;
            c) ITERATIONS=${OPTARG};;
            r) DNSRECORD=${OPTARG};;
            t) SLEEP_INTERVAL=${OPTARG};;
            \?) usage
                exit 1;;
            esac
    done
}

usage() {

    echo "Usage: $0 [-d DNS record to query] [-i IP DNS record should resolve to] "
    echo "          [-c number of times to query each server] [ -r DNS resource record type ]"
    echo "          [-t number of seconds to sleep between queries] server1 server2 ..."
}

# Parse the command line arguments and shift arguments to get the list of servers to query.
parse "$@"
shift "$((OPTIND-1))"

if [ $# -eq 0 ];then
    usage
    exit 1
fi

for dnsserver in ${@}; do
    dnstest ${dnsserver}
done