#!/bin/sh
# Created by Brian Weber <brian@bdweber.net> Jan 5, 2012
# check_file_md5s
# Checks the md5sum of a particular file against one stored in a predetermined list.
# No arguments will return usage.
# Please read usage statement for further detail.

# Modeled after / inspired by / replacing check_file_md5s by Stephen Berg, et al. 

VERSION=0.1

MD5=`which md5sum`
MD5_LIST="/usr/local/nagios/md5s"


function check_file_md5() {
	if [ -f $ARG ]; then
		if [ `grep $ARG $MD5_LIST | wc -l` -eq 1 ]; then
			if [ `grep $ARG $MD5_LIST | cut -d\  -f1` = `$MD5 $ARG | cut -d\  -f1` ]; then 
				echo OK 
				exit 0
			else 
				echo "WARNING - md5sum does not match! Rebuilding so the next check will match."
				rebuild_md5_list
				exit 2
			fi
		else
			echo "WARNING - md5sum is not in list. Adding for you now."
			echo `$MD5 $ARG` >> $MD5_LIST
			exit 1
		fi
	else
		echo "CRITICAL - file does not exist!"
		exit 2
	fi
}

function show_usage() {
	echo ""
	echo "    $0 - plugin for checking arbitrary md5sum against a predetermined list."
	echo "    This list lives at $MD5_LIST"
	echo "    New files need to be added by doing the following command:"
	echo "             $MD5 /path/to/file >> $MD5_LIST"
	echo ""
	echo "    Usage:   $0 /path/to/file"
	echo "             $0 --help"
	echo ""
	echo "    Version: $VERSION"
	echo ""
}

function rebuild_md5_list() {
	MD5_DATE=${MD5_LIST}.`date +%Y%m%d`
	mv $MD5_LIST $MD5_DATE 
	
	for FILE in `cat $MD5_DATE | awk '{ print $2 }' | sort | uniq | xargs`; do
		md5sum ${FILE} >> $MD5_LIST 
	done
}

if [ -z "$1" ]; then
	show_usage
	exit 2
fi

case $1 in
	--help)
		show_usage
		exit 0
		;;
	*)
		ARG=$1
		check_file_md5
		;;
esac