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

#FIXME - require-util

Version='0.2.7'
ConfFile='/etc/dns-check.conf'
DataDir='/var/lib/dns-check/'
RetVal=0	#True, everthing's unchanged from last time
MaxTries=10	#Number of times we'll try to request a given record.

usage () {
	echo "dns-check version $Version" >&2
	echo "Usage:" >&2
	echo "  dns-check [-f ConfigFileName] [-d DataDirectory] [-h]" >&2
	echo "  default config file is /etc/dns-check.conf">&2
	echo "  default data directory is /var/lib/dns-check" >&2
	echo "  -h shows this help" >&2
	echo "Exiting." >&2
	exit 1
}

if [ ! -d /dev/fd ]; then
	echo 'WARNING. /dev/fd is not a directory.  It may be that you are running' >&2
	echo 'devfs and are not running devfsd.  To fix this, add the following' >&2
	echo 'line to /etc/rc.d/rc.local or some other script that runs at boot time' >&2
	echo '(and run it once by hand)' >&2
	echo '' >&2
	echo 'if [ ! -d /dev/fd ]; then cd /dev ; rm -f /dev/fd ; ln -sf ../proc/self/fd fd ; cd - >/dev/null ; fi' >&2
	echo '' >&2
	sleep 10
fi


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

ChangedFileCount=0

#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 $CurrentTries >&2
			DigOut="`dig +noadditional +norecursive @$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 $CurrentTries >&2
			DigOut="`dig +noadditional +norecursive @$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' >&2
		CurrentTries=$[ $CurrentTries + 1 ]
	done
	if [ -f $DataDir/$Server-$DnsObject-$Type ]; then
		#Compare to exsting version
		if ! diff -q <(cat $DataDir/$Server-$DnsObject-$Type | tr 'A-Z' 'a-z' | sort | uniq) <(echo "$DigOut" | tr 'A-Z' 'a-z' | sort | uniq) >/dev/null 2>/dev/null ; then
		#if [ "`echo \"$DigOut\" | sort | uniq`" != "`cat $DataDir/$Server-$DnsObject-$Type | sort | uniq`" ]; then
			RetVal=1	#False, comething changed
			echo "$Server-$DnsObject-$Type mismatch!"
			diff -bd --unified=0 <(cat $DataDir/$Server-$DnsObject-$Type | tr 'A-Z' 'a-z' | sort | uniq) <(echo "$DigOut" | tr 'A-Z' 'a-z' | sort | uniq) | grep -v '^+++' | grep -v '^---' | grep -v '^@@'
			ChangedFileCount=$[ $ChangedFileCount + 1 ]
			if [ $ChangedFileCount -eq 1 ]; then
				ChangedFiles="$Server-$DnsObject-$Type"
			else
				ChangedFiles="$ChangedFiles,$Server-$DnsObject-$Type"
			fi
		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
if [ $ChangedFileCount -eq 0 ]; then
	:
elif [ $ChangedFileCount -eq 1 ]; then
	echo
	echo If you agree with all the above changes, the following command will remove 
	echo the old file so it can be replaced with correct one on the next pass:
	echo ssh `whoami`@`hostname` \'rm -f $DataDir$ChangedFiles\'
else
	echo
	echo If you agree with all the above changes, the following command will remove 
	echo the old files so they can be replaced with correct ones on the next pass:
	echo ssh `whoami`@`hostname` \'rm -f $DataDir{$ChangedFiles}\'
fi
exec 0<&5 5<&-

exit $RetVal