#! /bin/bash

###
# Checks process using SNMP.
#
# @AUTHOR: Patrik Dufresne
# Copyright 2012 Patrik Dufresne
# Last modified 2012-12-22
# Please send all comments, suggestions, bugs and patches to (info AT patrikdufresne DOT com)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
###

# You should provide a meaningful VERSION
VERSION=0.2
# Who can be contacted about this?
AUTHOR="Patrik Dufresne"
# Name what is being checked to be printed out next to OK/WARNING/CRITICAL/UNKNOWN
SERVICE="PROCS"

BASE_HR_SWRUNNAME_OID=".1.3.6.1.2.1.25.4.2.1.2"

# replacement for the exit function, will cleanup any tempfiles or such before exiting
function cleanup {
	exit $1
}

declare -rx PROGNAME=${0##*/}
declare -rx PROGPATH=${0%/*}/

if [ -r "${PROGPATH}utils.sh" ] ; then
	source "${PROGPATH}utils.sh"
else
	echo "Can't find utils.sh. This plugin needs to be run from the same directory as utils.sh which is most likely something like /usr/lib/nagios/plugins or /usr/lib64/nagios/plugins"
	printf "Currently being run from %s\n" "$PROGPATH"
	# since we couldn't define STATE_UNKNOWN since reading utils.sh failed, we use 3 here but everywhere else after this use cleanup $STATE
	cleanup 3
fi

# Set STATE to UNKNOWN as soon as we can (right after reading in util.sh where the STATES are defined)
STATE=$STATE_UNKNOWN

# make sure that any external commands are installed, in the PATH and executable. The following example is stupid because of course date is installed but it's the only command this trivial check really uses
SNMPWALK=`which snmpwalk`
if [ ! -x "$SNMPWALK" ] ; then
	echo "Snmpwalk is not installed, in your path and executable. Exiting."
	cleanup $STATE_UNKNOWN
fi

# provide a quick one liner of how to use the program
function usage {
	printf "%s %s for Nagios - Usage %s -H <hostname> -n <process-name> [-w <range>] [-c <range>] [-C <community>] [-p <port>] [-t <timeout>] [-v [-v [-v]]]\n" "$PROGNAME" "$VERSION" "$PROGNAME"
	cleanup $STATE_UNKNOWN
}

# provide detailed explanations of the command line syntax
function longhelp {
	# put your long help here
	printf "%s plugin version %s for Nagios by %s
  -h, --help                Display this message.
  -w, --warning=range       Set the warning threshold (default: 0:).
  -c, --critical=range      Set the critical threshold (default: 0:).
  -H, --host=hostname       Set the hostname or IP address.
  -C, --community=community Set the community string (default: public).
  -p, --port= port          Set the snmp port to use (default: 161) .
  -n, --name=process        Set the process name.
  -t, --timeout=sec         Set script timeout in seconds (default: 15).
  -v, --verbose             Up the verbosity level by one.
  --verbosity=val           Set the verbosity level to val.
  -V, --version             Print version information.
" "$PROGNAME" "$VERSION" "$AUTHOR"
	cleanup $STATE_UNKNOWN
}

# explanatory function you probably want to keep
function range_help {
	printf "
The format for ranges in Nagios can be confusing and it isn't always followed.

[@]start[:[end]]

Here are some example ranges:

Range   |  Generate an alert if value is    |  In English
--------+-----------------------------------+---------------------------------
10      |  outside the range of {0 .. 10}   |  Greater than 10
@10     |  inside the range of {0 .. 10}    |  Less than or equal to 10
10:     |  outside {10 .. ∞}                |  Greater than 10
~:10    |  outside the range of {-∞ .. 10}  |  Less than 10 including negative
10:20   |  outside the range of {10 .. 20}  |  Between 10 and 20
@10:20  |  inside the range of {10 .. 20}   |  Anything from 10 to 20
10      |  outside the range of {0 .. 10}   |  Greater than 10 or less than 0

Formal Rules:
1. start ≤ end
2. start and ":" is not required if start=0
3. if range is of format \"start:\" and end is not specified, end is infinity
4. to specify negative infinity, use "~"
5. alert is raised if metric is outside start and end range (inclusive)
6. if range starts with "@", then alert if inside this range (inclusive)
    10      < 0 or > 10, (outside the range of {0 .. 10})
    10:     < 10, (outside {10 .. ∞})
    ~:10    > 10, (outside the range of {-∞ .. 10})
    10:20   < 10 or > 20, (outside the range of {10 .. 20})
    @10:20  ≥ 10 and ≤ 20, (inside the range of {10 .. 20})
    10      < 0 or > 10, (outside the range of {0 .. 10})

More help at http://nagiosplug.sourceforge.net/developer-guidelines.html
"
	cleanup $STATE_UNKNOWN
}

if [ $# -eq 0 ] ; then
	usage
fi

# use getopt, trust me on this one. It's the easiest way
getopt -T
if [ $? -ne 4 ] ; then
	printf "%s: getopt is in compatibility mode.\n" "$SCRIPT"
	cleanup $STATE_UNKNOWN
fi

# tell it which switches and longswitches you'll take and place a trailing colon (:) on the ones take arguments
# Nagios guidelines require you to use all the ones specified below with the exception of --verbosity which I've added to circumvent the awkward -v -v -v syntax
# getopt takes care of positional parameters and errors for missing expected arguments so we can shift later without checking
RESULT=`getopt --name "$SCRIPT" --options "-h,-V,-v,-c:,-w:,-H:-C:,-p:,-n:,-t:" --longoptions "help,version,verbose,verbosity:,warning:,critical:,host:,community:,port:,name,timeout:" -- "$@"`

# make the result of getopt your new argument list ($@)
eval set -- "$RESULT"

WARNING="0:"
CRITICAL="0:"
declare -i TIMELIMIT=15
declare -i VERBOSITY=0
COMMUNITYSTRING=public
declare -i PORT=161
declare PROCESS
declare HOST

while [ $# -gt 0 ] ; do
	case "$1" in
		-h | --help)
			longhelp;;
		-V | --version)
			print_revision "$PROGNAME" "$VERSION"
			cleanup $STATE;;
		-v | --verbose)
			VERBOSITY=$(($VERBOSITY + 1));;
		--verbosity) # THIS IS NOT IN THE DEVELOPER GUIDELINES BUT FEELS MORE NATURAL THAN -v -v -v
			shift
			VERBOSITY=$1;;
		-w | --warning)
			shift
			WARNING=$1;;
		-c | --critical)
			shift
			CRITICAL=$1;;
		-H | --host)
			shift
			HOST=$1;;
		-C | --community)
			shift
			COMMUNITYSTRING=$1;;
		-p | --port)
			shift
			PORT=$1;;
		-n | --name)
			shift
			PROCESS=$1;;
		-t | --timeout)
			shift
			TIMELIMIT=$1;;
		--)
			shift
			break;;
		*)
			echo "Option $1 not supported. Ignored." >&2;;
	esac
	shift
done

#Verbosity level	Type of output
#0			Single line, minimal output. Summary
#1			Single line, additional information (eg list processes that fail)
#2			Multi line, configuration debug output (eg ps command used)
#3			Lots of detail for plugin problem diagnosis
if [ $VERBOSITY -gt 2 ] ; then
	shopt -o -s xtrace
fi

# Check argument values
if [ -z "$WARNING" -o -z "$CRITICAL" ] ; then
	echo "Please provide warning and critical threshold."
	usage
else
	# positive values only
	WARNFORMAT=`echo "$WARNING" | grep -c '^@\?\([0-9]\+:[0-9]*\|[0-9]\+\)$'`
	CRITFORMAT=`echo "$CRITICAL" | grep -c '^@\?\([0-9]\+:[0-9]*\|[0-9]\+\)$'`
	OK=$(( $WARNFORMAT + $CRITFORMAT ))
	if [ $OK -lt 2 ] ; then
		echo "Please check the format of your warning and critical thresholds."
		range_help
	fi
fi
if [ -z "$HOST" ]; then
	echo "Please provide hostname."
	usage
fi
if [ -z "$PROCESS" ]; then
	echo "Please provide process name."
	usage
fi

# what needs to happen in the event of a timeout
function timeout {
	echo "$SERVICE UNKNOWN - script timed out after $TIMELIMIT seconds."
	cleanup $STATE_UNKNOWN
}

# since we've processed the options which potentially set the timeout limit, we can setup a timeout trap now
trap timeout USR1
	( sleep $TIMELIMIT; if [ `pgrep -U $USER -f "$SCRIPT" | grep -c ^$$$` -gt 0 ] ; then kill -USR1 $$ ; fi; ) </dev/null &>/dev/null &

	DATA=`snmpwalk -v 2c -c "$COMMUNITYSTRING" "$HOST:$PORT" "$BASE_HR_SWRUNNAME_OID" 2>&1`
	RETURN=$?
	if [ $RETURN -gt 0 ]; then
		printf "%s UNKNOWN - %s\n" "$SERVICE" "$DATA"
		cleanup $STATE_UNKNOWN
	fi
	VALUE=`echo "$DATA" | grep -c "STRING: \"${PROCESS}\""`

	# once we're done doing work that could take any real time, we can end the trap because from here on out it's just comparisons and string concatenation
trap - USR1

function check_value {
	# if the range starts with an @, alert if value is inside the range, otherwise alert if value is outside of range
	INSIDE=`echo "$1" | grep -c '^@'`
	RANGE=`echo "$1" | sed 's/^@//'`

	# start is anything left of the colon or 0
	# end is anything right of the colon or the whole string if there's no colon or infinity if there is a colon and nothing to the right of it

	# is there a colon?
	PARTS=`echo "$RANGE" | awk -F : '{ print NF }'`
	if [ $PARTS -gt 1 ] ; then
		START=${RANGE%%:*}
		END=${RANGE##*:}
	else
		START=0
		END=$RANGE
	fi

	# 4. to specify negative infinity, use "~"
	if [ "$START" == "~" ] ; then
		START=-999999999
	fi

	if [ -z "$END" ] ; then
		END=999999999
	fi

	if [ $START -gt $END ] ; then
		echo "In threshold START:END, START must be less than or equal to END"
		range_help
	fi

	# if the range starts with an @, alert if value is inside the range, otherwise alert if value is outside of range
	# all ranges are inclusive of endpoints so we use less than or equal on the inside and just less than on the outside
	if [ "$INSIDE" -gt 0 ] ; then
		if [ "$START" -le "$2" -a "$2" -le "$END" ] ; then
			return 1
		fi
	else
		if [ "$2" -lt "$START" -o "$END" -lt "$2" ] ; then
			return 1
		fi
	fi

	return 0
}

# check conditions - yes this is ugly, blame BASH. If you want to blame me, please provide a cleaner way that is as fast or faster
check_value "$CRITICAL" "$VALUE"
if [ $? -gt 0 ] ; then
	STATE=$STATE_CRITICAL
else
	check_value "$WARNING" "$VALUE"
	if [ $? -gt 0 ] ; then
		STATE=$STATE_WARNING
	else
		STATE=$STATE_OK
	fi
fi

# STATE - Message | 'label'=value[unit of measure];[warn];[crit];[min];[max]
OUT="$VALUE processes with command name '$PROCESS' | procs=${VALUE};$WARNING;$CRITICAL"

case $STATE in
	$STATE_OK)
		printf "%s OK - %s\n" "$SERVICE" "$OUT";;
	$STATE_WARNING)
		printf "%s WARNING - %s\n" "$SERVICE" "$OUT";;
	$STATE_CRITICAL)
		printf "%s CRITICAL - %s\n" "$SERVICE" "$OUT";;
	$STATE_UNKNOWN)
		printf "%s UNKNOWN - %s\n" "$SERVICE" "$OUT";;
esac

cleanup $STATE