1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
|
# Copyright 2016 Rackspace Inc.
#
# Author: Tim Simmons <tim.simmons@rackspace>
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.mport threading
import dns
import dns.exception
import dns.query
from oslo_config import cfg
from oslo_log import log as logging
LOG = logging.getLogger(__name__)
CONF = cfg.CONF
def prepare_msg(zone_name, rdatatype=dns.rdatatype.SOA, notify=False):
"""
Do the needful to set up a dns packet with dnspython
"""
dns_message = dns.message.make_query(zone_name, rdatatype)
if notify:
dns_message.set_opcode(dns.opcode.NOTIFY)
else:
dns_message.set_opcode(dns.opcode.QUERY)
return dns_message
def dig(zone_name, host, rdatatype, port=53):
"""
Set up and send a regular dns query, datatype configurable
"""
query = prepare_msg(zone_name, rdatatype=rdatatype)
return send_dns_msg(query, host, port=port)
def notify(zone_name, host, port=53):
"""
Set up a notify packet and send it
"""
msg = prepare_msg(zone_name, notify=True)
return send_dns_msg(msg, host, port=port)
def send_dns_msg(dns_message, host, port=53):
"""
Send the dns message and return the response
:return: dns.Message of the response to the dns query
"""
# This can raise some exceptions, but we'll catch them elsewhere
if not CONF['service:mdns'].all_tcp:
return dns.query.udp(
dns_message, host, port=port, timeout=10)
else:
return dns.query.tcp(
dns_message, host, port=port, timeout=10)
def get_serial(zone_name, host, port=53):
"""
Possibly raises dns.exception.Timeout or dns.query.BadResponse.
Possibly returns 0 if, e.g., the answer section is empty.
"""
resp = dig(zone_name, host, dns.rdatatype.SOA, port=port)
if not resp.answer:
return 0
rdataset = resp.answer[0].to_rdataset()
if not rdataset:
return 0
return rdataset[0].serial
|
