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

#One possible call:
#if /usr/src/dns-check/dns-check ; then \
#echo Nothing has changed since the files were last written, good. \
#; else echo Content has either changed or been added. ; fi

#If everything's OK, the script will produce no output at all.

ConfFile='/etc/dns-check.conf'
DataDir='/var/lib/dns-check/'
RetVal=0	#True, everthing's unchanged from last time

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
		;;
	*)
		echo Unrecognized command line option "$1"
		;;
	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 ; do
	#echo Server "$Server" DnsObject "$DnsObject" Type "$Type"
	DigOut="`dig @$Server $DnsObject $Type | sed -e 's/;.*//' | grep -v '^$' | awk '{print $1, $3, $4, $5, $6, $7, $8, $9}' | sort`"
	if [ -f $DataDir/$Server-$DnsObject-$Type ]; then
		#Compare to exsting version
		if [ "$DigOut" != "`cat $DataDir/$Server-$DnsObject-$Type`" ]; then
			RetVal=1	#False, comething changed
			echo "$Server-$DnsObject-$Type mismatch!"
			echo Old version:
			cat "$DataDir/$Server-$DnsObject-$Type" | sed -e 's/^/     /'
			echo New Version:
			echo "$DigOut" | sed -e 's/^/     /'
		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" | sort >"$DataDir/$Server-$DnsObject-$Type"
	fi
done
exec 0<&5 5<&-

exit $RetVal