#! /bin/sh
#
# Log file pattern detector plugin for Nagios
# Written by Ethan Galstad (nagios@nagios.org)
# Last Modified: 07-31-1999
#
# Usage: ./check_log <log_file> <old_log_file> <pattern>
#
# Description:
#
# This plugin will scan a log file (specified by the <log_file> option)
# for a specific pattern (specified by the <pattern> option).  Successive
# calls to the plugin script will only report *new* pattern matches in the
# log file, since an copy of the log file from the previous run is saved
# to <old_log_file>.
#
# Output:
#
# On the first run of the plugin, it will return an OK state with a message
# of "Log check data initialized".  On successive runs, it will return an OK
# state if *no* pattern matches have been found in the *difference* between the
# log file and the older copy of the log file.  If the plugin detects any 
# pattern matches in the log diff, it will return a CRITICAL state and print
# out a message is the following format: "(x) last_match", where "x" is the
# total number of pattern matches found in the file and "last_match" is the
# last entry in the log file which matches the pattern.
#
# Notes:
#
# If you use this plugin make sure to keep the following in mind:
#
#    1.  The "max_attempts" value for the service should be 1, as this
#        will prevent Nagios from retrying the service check (the
#        next time the check is run it will not produce the same results).
#
#    2.  The "notify_recovery" value for the service should be 0, so that
#        Nagios does not notify you of "recoveries" for the check.  Since
#        pattern matches in the log file will only be reported once and not
#        the next time, there will always be "recoveries" for the service, even
#        though recoveries really don't apply to this type of check.
#
#    3.  You *must* supply a different <old_file_log> for each service that
#        you define to use this plugin script - even if the different services
#        check the same <log_file> for pattern matches.  This is necessary
#        because of the way the script operates.
#
# Examples:
#
# Check for login failures in the syslog...
#
#   check_log /var/log/messages ./check_log.badlogins.old "LOGIN FAILURE"
#
# Check for port scan alerts generated by Psionic's PortSentry software...
#
#   check_log /var/log/message ./check_log.portscan.old "attackalert"
#

# Paths to commands used in this script.  These
# may have to be modified to match your system setup.

PATH=""

ECHO="/bin/echo"
GREP="/bin/grep"
DIFF="/usr/bin/diff"
TAIL="/usr/bin/tail"
CAT="/bin/cat"
RM="/bin/rm"

PROGNAME=`/usr/bin/basename $0`
PROGPATH=`echo $0 | /bin/sed -e 's,[\\/][^\\/][^\\/]*$,,'`
REVISION=`echo '$Revision: 1.4 $' | /bin/sed -e 's/[^0-9.]//g'`

. $PROGPATH/utils.sh

print_usage() {
    echo "Usage: $PROGNAME -F logfile -O oldlog -q query"
    echo "Usage: $PROGNAME --help"
    echo "Usage: $PROGNAME --version"
}

print_help() {
    print_revision $PROGNAME $REVISION
    echo ""
    print_usage
    echo ""
    echo "Log file pattern detector plugin for Nagios"
    echo ""
    support
}

# Make sure the correct number of command line
# arguments have been supplied

if [ $# -lt 1 ]; then
    print_usage
    exit $STATE_UNKNOWN
fi

# Grab the command line arguments

#logfile=$1
#oldlog=$2
#query=$3
exitstatus=$STATE_WARNING #default
while test -n "$1"; do
    case "$1" in
        --help)
            print_help
            exit $STATE_OK
            ;;
        -h)
            print_help
            exit $STATE_OK
            ;;
        --version)
            print_revision $PROGNAME $VERSION
            exit $STATE_OK
            ;;
        -V)
            print_revision $PROGNAME $VERSION
            exit $STATE_OK
            ;;
        --filename)
            logfile=$2
            shift
            ;;
        -F)
            logfile=$2
            shift
            ;;
        --oldlog)
            oldlog=$2
            shift
            ;;
        -O)
            oldlog=$2
            shift
            ;;
        --query)
            query=$2
            shift
            ;;
        -q)
            query=$2
            shift
            ;;
        -x)
            exitstatus=$2
            shift
            ;;
        --exitstatus)
            exitstatus=$2
            shift
            ;;
        *)
            echo "Unknown argument: $1"
            print_usage
            exit $STATE_UNKNOWN
            ;;
    esac
    shift
done

# If the source log file doesn't exist, exit

if [ ! -e $logfile ]; then
    $ECHO "Log check error: Log file $logfile does not exist!\n"
    exit $STATE_UNKNOWN
elif [ ! -r $logfile ] ; then
    $ECHO "Log check error: Log file $logfile is not readable!\n"
    exit $STATE_UNKNOWN
fi

# If the old log file doesn't exist, this must be the first time
# we're running this test, so copy the original log file over to
# the old diff file and exit

if [ ! -e $oldlog ]; then
    $CAT $logfile > $oldlog
    $ECHO "Log check data initialized...\n"
    exit $STATE_OK
fi

# The old log file exists, so compare it to the original log now

# The temporary file that the script should use while
# processing the log file.
if [ -x /bin/mktemp ]; then
    tempdiff=`/bin/mktemp /tmp/check_log.XXXXXXXXXX`
else
    tempdiff=`/bin/date '+%H%M%S'`
    tempdiff="/tmp/check_log.${tempdiff}"
    /bin/touch $tempdiff
    chmod 600 $tempdiff
fi

$DIFF $logfile $oldlog > $tempdiff

# Count the number of matching log entries we have
count=`$GREP -c "$query" $tempdiff`

# Get the last matching entry in the diff file
lastentry=`$GREP "$query" $tempdiff | $TAIL --lines=1`

$RM -f $tempdiff
$CAT $logfile > $oldlog

if [ "$count" = "0" ]; then # no matches, exit with no error
    $ECHO "Log check ok - 0 pattern matches found\n"
    exitstatus=$STATE_OK
else # Print total matche count and the last entry we found
    $ECHO "($count) $lastentry"
    exitstatus=$STATE_CRITICAL
fi

exit $exitstatus
