#!/bin/bash
#set -x
#
# License: The BSD 3-Clause License
#
# Copyright (c) 2014, Johan Ryberg
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without 
# modification, are permitted provided that the following conditions are met:
# 
# 1. Redistributions of source code must retain the above copyright notice, 
#  this list of conditions and the following disclaimer.
# 
# 2. Redistributions in binary form must reproduce the above copyright notice,
#  this list of conditions and the following disclaimer in the documentation
#  and/or other materials provided with the distribution.
# 
# 3. Neither the name of the copyright holder nor the names of its contributors
#  may be used to endorse or promote products derived from this software without
#  specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
#  POSSIBILITY OF SUCH DAMAGE.
#
# check_reboot-required
# Plugin for NRPE (Nagios Remote Plugin Executor) for Debian/Ubuntu to check
# if a reboot are required and also list packages that requires reboot
# Web: https://github.com/jryberg/nagios-plugins/

APPNAME=`basename $0`
VERSION="1.0"

# Defining standard messages and exit error levels
# https://nagios-plugins.org/doc/guidelines.html
OK_EXIT_CODE=0
WARNING_EXIT_CODE=1
CRITICAL_EXIT_CODE=2
UNKNOWN_EXIT_CODE=3
OK_MSG="OK"
WARNING_MSG="Warning"
CRITICAL_MSG="Critical"
UNKNOWN_MSG="Unknown"

# Using Unknown as default
EXIT_CODE=$UNKNOWN_EXIT_CODE
EXIT_MSG=$UNKNOWN_MSG

# Stupid warning and critical levels, this cannot be determined by numbers
# some may want to have this anyway. Default will be a warning if a reboot
# are required and never critical
# -1 = disable service status
WARNING_LEVEL=1
CRITICAL_LEVEL=-1

# Path to reboot-required
REBOOT_REQUIRED_PATH="/var/run/reboot-required"
REBOOT_REQUIRED_PKGS_PATH="/var/run/reboot-required.pkgs"

# Function to explain how to use the program
function_usage () {
cat - <<EOF
Usage: ${appname} [--help]
Usage: ${appname} -d status [-w warn] [-c crit]

This check command checks if a reboot are required after an upgrade. It will
also list packages that requires a reboot to ease the decision for the
sysadmin if/when a reboot needs to be carried out.

WARNING: It's impossible by numbers to decide if a reboot are required by
raising a "warning" or "critical" event. A patch for 0-day vulnerability
will probably required immediate attention and less important updates can
wait until next scheduled maintenance window. Please read documentation
for each update.

Default without any options will be Warning for 1 or more packages
that requires reboot. Critical event will not be raised.

 --help
    Show this help
 -V, --version
    Show version
 -s
    Default service status when reboot are needed but package information
    are missing. w=Warning, c=Critical
 -w
    Warning: Number of packages needing reboot as integer. Default: 1
 -c
    Critical: Number of packages needing reboot as integer. Disabled as default

Example:
${APPNAME} -s w

EOF
}

# Process arguments
while [ $# -gt 0 ]
    do
        OPT="$1"
            case "${OPT}" in
                --help)
                    function_usage
                    exit $OK_EXIT_CODE
                ;;
                -s)
                    shift
                    if [[ ${1} =~ ^[w|c]$ ]]; then
                        STATUS="${1}"
                    else
                        echo "${APPNAME}: Service status must be w (Warning) or c (Critical)"
                        exit $UNKNOWN_EXIT_CODE
                    fi
                    shift
                ;;
                -w)
                    shift
                    if [[ ${1} =~ ^[0-9]+$ ]]; then
                        WARNING_LEVEL="${1}"
                    else
                        echo "${APPNAME}: Warning level must be positive integer"
                        exit $UNKNOWN_EXIT_CODE
                    fi
                    shift
                ;;
                -c)
                    shift
                    if [[ ${1} =~ ^[0-9]+$ ]]; then
                        CRITICAL_LEVEL="${1}"
                    else
                        echo "${APPNAME}: Critical level must be positive integer"
                        exit $UNKNOWN_EXIT_CODE
                    fi
                    shift 
                ;;
                --version|-V)
                    echo "${APPNAME} ${VERSION}"
                    exit $OK_EXIT_CODE
                ;;
                *)
                    echo "${APPNAME}: invalid option '${1}'"
                    echo "Try '${APPNAME} --help' for more information."
                    exit $UNKNOWN_EXIT_CODE
                ;;
    esac
done

if [ -z ${STATUS} ]; then
    echo "${APPNAME}: -s Status argument are missing"
    exit $UNKNOWN_EXIT_CODE
fi

if [ ! -f ${REBOOT_REQUIRED_PATH} ]; then
    # Reboot not required
    EXIT_MSG=$OK_MSG
    EXIT_MSG_BODY="No reboot required|Packages=0;${WARNING_LEVEL//-1/};${CRITICAL_LEVEL//-1/};0"
    EXIT_MSG_NR_PACKAGES=0
    EXIT_CODE=$OK_EXIT_CODE
else
    # Reboot required
    NR_OF_PACKAGES=0
    if [ -f ${REBOOT_REQUIRED_PKGS_PATH} ]; then
        NR_OF_PACKAGES=`wc -l ${REBOOT_REQUIRED_PKGS_PATH} | awk '{ print $1 }'`
    fi

    if [ ${NR_OF_PACKAGES} -gt 0 ]; then
        if [ ${NR_OF_PACKAGES} -ge ${CRITICAL_LEVEL} ] && [ ${CRITICAL_LEVEL} -ne "-1" ];then
            EXIT_MSG=$CRITICAL_MSG
            EXIT_CODE=$CRITICAL_EXIT_CODE
        elif [ ${NR_OF_PACKAGES} -ge ${WARNING_LEVEL} ] && [ ${WARNING_LEVEL} -ne "-1" ];then
            EXIT_MSG=$WARNING_MSG
            EXIT_CODE=$WARNING_EXIT_CODE
        else
            EXIT_MSG=$OK_MSG
            EXIT_CODE=$OK_EXIT_CODE
        fi
        EXIT_MSG_BODY="`cat ${REBOOT_REQUIRED_PATH}`<br/>Packages:<br/>`cat ${REBOOT_REQUIRED_PKGS_PATH} | sed ':a;N;$!ba;s/\n/<br\/>/g'`|Packages=${NR_OF_PACKAGES};${WARNING_LEVEL//-1/};${CRITICAL_LEVEL//-1/};0"
    else
        if [[ ${STATUS} = "w" ]]; then
            EXIT_MSG=$WARNING_MSG
            EXIT_CODE=$WARNING_EXIT_CODE
        else
            EXIT_MSG=$CRITICAL_MSG
            EXIT_CODE=$CRITICAL_EXIT_CODE
        fi
        EXIT_MSG_BODY="`cat ${REBOOT_REQUIRED_PATH}`|Packages=U;${WARNING_LEVEL//-1/};${CRITICAL_LEVEL//-1/};0"
    fi
fi

# Echo message and exit
echo "${EXIT_MSG}: ${EXIT_MSG_BODY}"
exit $EXIT_CODE