#!/bin/bash
#Copyright 2002 William Stearns <wstearns@pobox.com>
#Released under the GPL.

#FIXME - require-util

Version='0.2'
ConfFile='/etc/dns-check.conf'
DataDir='/var/lib/dns-check/'
RetVal=0	#True, everthing's unchanged from last time
MaxTries=3	#Number of times we'll try to request a given record.

usage () {
	echo "dns-check version $Version" >>/dev/stderr
	echo "Usage:" >>/dev/stderr
	echo "  dns-check [-f ConfigFileName] [-d DataDirectory] [-h]" >>/dev/stderr
	echo "  default config file is /etc/dns-check.conf">>/dev/stderr
	echo "  default data directory is /var/lib/dns-check" >>/dev/stderr
	echo "  -h shows this help" >>/dev/stderr
	echo "Exiting." >>/dev/stderr
	exit 1
}


while [ -n "$1" ]; do
	case "$1" in
	-f)
		if [ -n "$2" ]; then
			ConfFile="$2"
			shift
		else
			echo Missing file name for '-f' option.  Exiting.
			exit 1
		fi
		;;
	-d)
		if [ -n "$2" ]; then
			DataDir="$2"
			shift
		else
			echo Missing Data Directory for '-d' option.  Exiting.
			exit 1
		fi
		;;
	-h)
		usage
		;;
	*)
		echo Unrecognized command line option "$1"
		usage
		;;
	esac
	shift
done

if [ ! -r "$ConfFile" ]; then
	echo Missing or unreadable configuration file "$ConfFile".  Exiting.
	exit 1
fi
if [ ! -d "$DataDir" ]; then
	echo Missing Data Directory "$DataDir".  Exiting.
	exit 1
fi

#Two less-thans is correct, really.
exec 5<&0 < <(cat "$ConfFile" | sed -e 's/#.*//' | grep -v '^$' )
while read Server DnsObject Type TsigKey ; do
	CurrentTries=0
	DigOut=''
	while [ "$DigOut" = '' ] && [ $CurrentTries -lt $MaxTries ]; do
		if [ -n "$TsigKey" ]; then
			#echo Server "$Server" DnsObject "$DnsObject" Type "$Type" TsigKey "$TsigKey" Attempt $CurrentTries >>/dev/stderr
			DigOut="`dig @$Server $DnsObject $Type -y $TsigKey | sed -e 's/;.*//' | grep -v '^$' | grep -v 'ANY.*TSIG' | awk '{print $1, $3, $4, $5, $6, $7, $8, $9}'`"
		else
			#echo Server "$Server" DnsObject "$DnsObject" Type "$Type" Attempt $CurrentTries >>/dev/stderr
			DigOut="`dig @$Server $DnsObject $Type | sed -e 's/;.*//' | grep -v '^$' | grep -v 'ANY.*TSIG'| awk '{print $1, $3, $4, $5, $6, $7, $8, $9}'`"
		fi
		#echo 'XX'"$DigOut"'XX' >>/dev/stderr
		CurrentTries=$[ $CurrentTries + 1 ]
	done
	if [ -f $DataDir/$Server-$DnsObject-$Type ]; then
		#Compare to exsting version
		if ! diff -q <(cat $DataDir/$Server-$DnsObject-$Type | sort) <(echo "$DigOut" | sort) >/dev/null 2>/dev/null ; then
		#if [ "`echo \"$DigOut\" | sort`" != "`cat $DataDir/$Server-$DnsObject-$Type | sort`" ]; then
			RetVal=1	#False, comething changed
			echo "$Server-$DnsObject-$Type mismatch!"
			diff -bd --unified=0 <(cat $DataDir/$Server-$DnsObject-$Type | sort) <(echo "$DigOut" | sort) | grep -v '^+++' | grep -v '^---' | grep -v '^@@'
		fi
	else
		RetVal=1	#False, new content added; someone should look into this.
		#Write it out for the first time for future comparison
		echo "Writing the following to $DataDir/$Server-$DnsObject-$Type for future compare."
		echo "$DigOut" | sed -e 's/^/     /'
		echo "$DigOut" >"$DataDir/$Server-$DnsObject-$Type"
	fi
done
exec 0<&5 5<&-

exit $RetVal