#!/usr/libexec/platform-python
"""
The Nagios plugin  to check outgoing mail IP's.
Copyright Taras K.
version 0.4.3
"""


try:
    from random import choice
    import sys
    import re
    import dns.name
    import dns.message
    import dns.query
    import dns.resolver
    import dns.reversename
except ImportError:
    print("CRITICAL - Module dns import error.")
    sys.exit(2)

omi_file = '/etc/outgoingmailip'
dip_file = '/etc/domainips'

is_dedicated = False

omi_fd = open(omi_file, 'r')
dip_fd = open(dip_file, 'r')


omi = omi_fd.readline()
omi = omi.rstrip()


def only_ip(rrdata, lname_server):
    ippat = r'\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}'
    match = re.search(ippat, rrdata)
    if match:
        return match.group()
    else:
        print("WARNING - Got bad answer from NS: "+lname_server)
        sys.exit(1)


def get_ns(domain):
    nc_ns = ('216.87.155.33','216.87.152.33')
    rootns = ('198.41.0.4', '192.228.79.201',
              '192.33.4.12', '199.7.91.13', '192.203.230.10', '192.5.5.241',
              '192.112.36.4', '128.63.2.53', '192.58.128.30',
              '193.0.14.129', '202.12.27.33')
    check_domain = domain
    srootns = choice(rootns)
    cleaned_domain = domain.split('.')
    if not cleaned_domain[-1].endswith('.'):
        cleaned_domain.extend('.')
    cleaned_domain.reverse()
    if '' in cleaned_domain:
        cleaned_domain.remove('')
# Split into parts in reverse for easier
# querying ['.','com.', 'google.com.', www.google.com.']
    i = 1
    while i < len(cleaned_domain):
        if i == 1:
            cleaned_domain[i] = cleaned_domain[i]+cleaned_domain[i-1]
        else:
            cleaned_domain[i] = cleaned_domain[i]+'.'+cleaned_domain[i-1]
        i += 1
    additional_ns = []
    for domain in cleaned_domain[1:]:
        name_server = srootns
        ndomain = dns.name.from_text(check_domain)
        request = dns.message.make_query(ndomain, dns.rdatatype.NS)
        if additional_ns:
            name_server = choice(additional_ns)
        try:
            response = dns.query.udp(request, name_server, timeout=10)
        except dns.exception.Timeout:
            print("WARNING - Dns query timed out. NS is unreachable.")
            sys.exit(1)
        additional_ns = []
# Skip IPv6
        for item in response.additional:
            if 'IN AAAA' not in item.to_text():
                ip_ns = only_ip(item.to_text(), name_server)
                if ip_ns:
                    additional_ns.append(only_ip(ip_ns, name_server))
        if additional_ns:
            LNS = choice(additional_ns)
        else:
            LNS = choice(nc_ns)
    return LNS


def check_ptr(ip):
    result = False
    try:
        my_resolver = dns.resolver.Resolver(configure=False)
        my_resolver.nameservers = ['4.2.2.3', '8.8.8.8', '8.8.4.4']
        ip_reverse_name = dns.reversename.from_address(ip)
        resolved_name = str(my_resolver.query(ip_reverse_name, 'ptr')[0])
        resolved_name = resolved_name.rstrip('.')
#        my_ns = get_ns(resolved_name)
#        my_resolver.nameservers = [my_ns]
        a_record = my_resolver.query(resolved_name)[0]
        if str(a_record) == str(ip):
            result = True
        else:
            result = False
    except dns.resolver.NXDOMAIN as myNX:
        print("CRITICAL - There is no A record in DNS")
        sys.exit(2)
    except Exception as my_exp:
        print("WARNING - General exception")
        sys.exit(1)
    return result


if check_ptr(omi) is False:
    print("CRITICAL - Outgoing mail IP!!! PTR and A record doesn't match.")
    sys.exit(2)
for line in dip_fd:
    if '#' not in line:
        line_splitted = line.split(':')
        if line_splitted[0] == omi:
            is_dedicated = True

if not is_dedicated:
    print("OK - Outgoing mail IP is OK")
    sys.exit(0)
else:
    print("CRITICAL - Outgoing mail IP is owned by client.")
    sys.exit(2)