#!/usr/bin/env python3
# -*- encoding: utf-8 -*-

#####################################################################
# (c) 2006-2011 by Sven Velt and team(ix) GmbH, Nuernberg, Germany  #
#                  sv@teamix.net                                    #
# (c) 2016- by Sven Velt, Germany                                   #
#              sven-mymonplugins@velt.biz                           #
#                                                                   #
# This file is part of "velt.biz - My Monitoring Plugins"           #
# a fork of "team(ix) Monitoring Plugins" in 2015                   #
# URL: https://gogs.velt.biz/velt.biz/MyMonPlugins/                 #
#                                                                   #
# This file 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, either version 2 of the License, #
# or (at your option) any later version.                            #
#                                                                   #
# This file 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 file. If not, see <http://www.gnu.org/licenses/>. #
#####################################################################

import fcntl
import socket
import struct
import sys

try:
	from MyMonPlugin import MonitoringPlugin
except ImportError:
	print('==========================')
	print('AIKS! Python import error!')
	print('==========================\n')
	print('Could not find class "MonitoringPlugin"!\n')
	print('Did you download "%s"' % os.path.basename(sys.argv[0]))
	print('without "MyMonPlugin/"?\n')
	print('Please go back to')
	print('https://gogs.velt.biz/velt.biz/MyMonPlugins and:')
	print('- get a full archive at http://gogs.velt.biz/velt.biz/MyMonPlugins/releases')
	print('- or a master snapshot at http://gogs.velt.biz/velt.biz/MyMonPlugins/archive/master.tar.gz\n')
	sys.exit(127)


def get_ipv4_address(iface):
	sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
	return socket.inet_ntoa(fcntl.ioctl(sock.fileno(), 0x8915, struct.pack('256s', bytes(iface[:15], 'utf-8')))[20:24])


plugin = MonitoringPlugin(pluginname='check_iface-dns', tagforstatusline='IFACE-DNS', description='Check interface address vs. DNS', version='0.1')

plugin.add_cmdlineoption('-i', '', 'iface', 'Interface to get IP from', default='lo')
plugin.add_cmdlineoption('-d', '', 'dns', 'DNS object(s) to check, comma separated list', default='localhost')
#plugin.add_cmdlineoption('-4', '', 'v4', 'Use IPv4', action='store_true')
#plugin.add_cmdlineoption('-6', '', 'v6', 'Use IPv6', action='store_true')

plugin.parse_cmdlineoptions()

#if not plugin.options.v4 and not plugin.options.v6:
#	plugin.options.v4 = True
#
#if plugin.options.v4:
#	plugin.verbose(1, 'Using IPv4')
#
#if plugin.options.v6:
#	plugin.verbose(1, 'Using IPv6')


# Get IP from interface
try:
	ip_iface = get_ipv4_address(plugin.options.iface)
except IOError as xxx_todo_changeme:
	(errno, strerror) = xxx_todo_changeme.args
	if errno == 19:
		plugin.back2nagios(2, 'Interface "%s" does not exist!' % plugin.options.iface)
	elif errno == 99:
		plugin.back2nagios(2, 'Interface "%s" has no IP!' % plugin.options.iface)

	plugin.back2nagios(2, 'I/O error(%s): %s, interface "%s"' % (errno, strerror, plugin.options.iface))

plugin.verbose(1, 'Found IP "%s" on interface "%s"' % (ip_iface, plugin.options.iface))

# Get IP(s) from DNS
if not ',' in plugin.options.dns:
	# Only one DNS object
	try:
		ip_dns = socket.gethostbyname(plugin.options.dns)
	except socket.gaierror:
		ip_dns = None
		plugin.back2nagios(1, 'Could not find "%s" in DNS!' % plugin.options.dns)

	if ip_iface == ip_dns:
		plugin.back2nagios(0, 'Found %s for "%s" in DNS and on interface "%s"' % (ip_dns, plugin.options.dns, plugin.options.iface))
	else:
		plugin.back2nagios(2, 'Found %s for "%s" in DNS, but %s for interface "%s"' % (ip_dns, plugin.options.dns, ip_iface, plugin.options.iface))

else:
	# Multiple DNS objects
	plugin.add_returncode(0)
	failed_dns = []

	for dns in plugin.options.dns.split(','):
		try:
			ip_dns = socket.gethostbyname(dns)
		except socket.gaierror:
			ip_dns = None

		if ip_dns:
			plugin.verbose(1, 'Found IP "%s" as DNS object "%s"' % (ip_dns, dns))
		else:
			plugin.verbose(1, 'Did not find IP for "%s"' % dns)

		if ip_iface != ip_dns:
			plugin.add_multilineoutput('CRITICAL - "%s" has unexpected IP "%s"' % (dns, ip_dns))
			failed_dns.append(dns)
		else:
			plugin.add_multilineoutput('OK - "%s" resolves to "%s"' % (dns, ip_dns))


	if len(failed_dns) == 0:
		plugin.add_returncode(0)
		plugin.add_output('All DNS objects have a correct IP')
	else:
		plugin.add_returncode(2)
		plugin.add_output('Following DNS objects did not resolve as expected: "%s"' % '", "'.join(failed_dns))

	plugin.exit()