#!/bin/sh

# Copyright 2017 alarig <alarig@grifon.fr>
#
# BSD-3-Clause licence
#
# 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.

# For debuggin purpose, uncomment the next line and `tail -F` the file.
#exec 2> /tmp/check_bgp.log

usage() {
	printf "Usage:\n"
	printf "check_bgp [-4|-6] -p session\n"
	printf "Must be run with user account able to use birdc/birdc6 or use"
	printf "-s to use birdc with sudo.\n"
}

args=$(getopt 46hsp: $*)

if [ $? -ne 0 ]; then
	usage
	exit 3
fi
set -- $args

while :; do
	case "$1" in
		-h)
			usage
			exit 0
			shift
			;;
		-4)
			VERSION="IPv4"
			shift
			;;
		-6)
			VERSION="IPv6"
			shift
			;;
		-s)
			SUDO='sudo'
			shift
			;;
		-p)
			SESSION="$2"
			shift; shift
			;;
		--)
			shift; break
			;;
	esac
done

# path expansion for birdc and sudo of FreeBSD
PATH="$PATH:/usr/local/sbin/:/usr/local/bin/"

if [ "${VERSION}" = "IPv4" ]; then
	birdc="${SUDO} birdc -r"
elif [ "${VERSION}" = "IPv6" ]; then
	birdc="${SUDO} birdc6 -r"
else
	printf "CRITICAL: Invalid IP version, use -4 for IPv4 and -6 for IPv6\n"
	exit 2
fi

if [ -z ${SESSION} ]; then
	printf "CRITICAL: No session name supplied, use -p \$session.\n"
	exit 2
fi

STATE="$($birdc show protocol ${SESSION} | \
	awk -v session=${SESSION} '$0 ~ session { print $6 }')"

ROUTE_LIMIT_IN="$($birdc show protocol all ${SESSION} | \
	awk '/Receive limit/ { print $3 }')"

# Test if we are on a bird2
if [ -z ${ROUTE_LIMIT_IN} ]; then
	ROUTE_LIMIT_IN="$($birdc show protocol all ${SESSION} | \
		awk '/Import limit/ { print $3 }')"
fi

# There is no import limit, so no ratio either
if [ -z ${ROUTE_LIMIT_IN} ]; then
	RATIO_IN=0
fi

ROUTES_IMPORTED="$($birdc show protocol all ${SESSION} | grep 'Routes:' | \
	sed -Ee '/imported/{ s/^.* ([0-9]+) imported.*$/\1/; p;}' -e d)"
ROUTE_HIT_IN="$($birdc show protocol all ${SESSION} | \
	grep -E 'Receive limit:.*HIT')"

if [ ! -z ${ROUTE_LIMIT_IN} ]; then
	RATIO_IN=$(echo "(${ROUTES_IMPORTED}*100)/${ROUTE_LIMIT_IN}" | bc)
fi

ROUTE_HIT_OUT="$($birdc show protocol all ${SESSION} | \
	grep -E 'Export limit:.*HIT')"

# Session states: https://gitlab.labs.nic.cz/labs/bird/blob/master/proto/bgp/bgp.c#L1465
# Plugin return codes: https://nagios-plugins.org/doc/guidelines.html#AEN78

case ${STATE} in
	Established)
		if [ "${ROUTE_HIT_IN}" != "" ]; then
			printf "CRITICAL: ${SESSION} has hit import route "
			printf "limit\n"
			exit 2
		elif [ "${ROUTE_HIT_OUT}" != "" ]; then
			printf "CRITICAL: ${SESSION} has hit export route "
			printf "limit\n"
			exit 2
		elif [ ${RATIO_IN} -gt 92 ]; then
			printf "WARNING: ${SESSION} import route limit is "
			printf "over threshold\n"
			exit 1
		else
			printf "OK: ${SESSION} is ${STATE}\n"
			exit 0
		fi
		;;
	OpenSent | OpenConfirm)
		printf "WARNING: ${SESSION} is in ${STATE} state\n"
		exit 1
		;;
	Idle | Connect | Active)
		printf "CRITICAL: ${SESSION} is in ${STATE} state\n"
		exit 2
		;;
	*)
		printf "Unknown state: ${STATE}\n"
		exit 3
		;;
esac