#!/bin/bash

# Checks if a given cert on disk will expire soon

# Copyright 2009, 2012 Peter Palfrader
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

set -u
set -e

# warn if expires within 2 weeks, critical if within a day or already is expired
warn=1209600
crit=86400

while [ "$#" -ge 2 ]; do
	case "$1" in
		-c)
			shift
			crit="$1"
			;;
		-w)
			shift
			warn="$1"
			;;
		*)
			break
			;;
	esac
	shift
done

if [ "$#" != 1 ]; then
	echo "Usage: $0 [-w <seconds>] [-c <seconds>] <crlfile>" >&2
	exit 3
fi

crl="$1"

if ! [ -r "$crl" ] ; then
	echo "CRL file ($crl) does not exist or is not readable" >&2
	exit 3
fi

expires="$(openssl crl -nextupdate -noout < "$crl" | cut -d = -f 2)"
expsec="$(date -d "$expires" +%s)"
now="$(date +%s)"
delta="$(( $expsec - $now ))"

if [ "$delta" -gt "$warn" ] ; then
	echo "OK: next update expected $expires"
	exit 0
fi
if [ "$delta" -gt "$crit" ] ; then
	echo "WARN: next update expected $expires"
	exit 1
fi
echo "CRITICAL: next update expected $expires"
exit 2