Source code for designate.mdns.notify

# Copyright (c) 2014 Rackspace Hosting
# All Rights Reserved.
#
#    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.

import socket
import time

import dns
import dns.exception
import dns.flags
import dns.message
import dns.opcode
import dns.rcode
import dns.rdataclass
import dns.rdatatype
import eventlet
from oslo_config import cfg
from oslo_log import log as logging

from designate import dnsutils
from designate.mdns import base
from designate.metrics import metrics

dns_query = eventlet.import_patched('dns.query')

LOG = logging.getLogger(__name__)
CONF = cfg.CONF


[docs]class NotifyEndpoint(base.BaseEndpoint): RPC_API_VERSION = '2.0' RPC_API_NAMESPACE = 'notify'
[docs] def notify_zone_changed(self, context, zone, host, port, timeout, retry_interval, max_retries, delay): """ :param context: The user context. :param zone: The designate zone object. This contains the zone name. :param host: A notify is sent to this host. :param port: A notify is sent to this port. :param timeout: The time (in seconds) to wait for a NOTIFY response from server. :param retry_interval: The time (in seconds) between retries. :param max_retries: The maximum number of retries mindns would do for sending a NOTIFY message. After this many retries, mindns gives up. :param delay: The time to wait before sending the first NOTIFY request. :return: a tuple of (response, current_retry) where response is the response on success or None on failure. current_retry is the current retry number. The return value is just used for testing and not by pool manager. """ start_time = time.time() try: time.sleep(delay) return self._make_and_send_dns_message( zone, host, port, timeout, retry_interval, max_retries, notify=True) finally: metrics.timing('mdns.notify_zone_changed', time.time() - start_time)
[docs] def poll_for_serial_number(self, context, zone, nameserver, timeout, retry_interval, max_retries, delay): return
[docs] def get_serial_number(self, context, zone, host, port, timeout, retry_interval, max_retries, delay): """ Get zone serial number from a resolver using retries. :param context: The user context. :param zone: The designate zone object. This contains the zone name. zone.serial = expected_serial :param host: A notify is sent to this host. :param port: A notify is sent to this port. :param timeout: The time (in seconds) to wait for a SOA response from nameserver. :param retry_interval: The time (in seconds) between retries. :param max_retries: The maximum number of retries mindns would do for an expected serial number. After this many retries, mindns returns an ERROR. :param delay: The time to wait before sending the first request. :return: a tuple of (status, actual_serial, retries) status is either "SUCCESS" or "ERROR". actual_serial is either the serial number returned in the SOA message from the nameserver or None. retries is the number of retries left. The return value is just used for testing and not by pool manager. The pool manager is informed of the status with update_status. """ actual_serial = None status = 'ERROR' retries_left = max_retries time.sleep(delay) while True: response, retry_cnt = self._make_and_send_dns_message( zone, host, port, timeout, retry_interval, retries_left) if response and (response.rcode() in (dns.rcode.NXDOMAIN, dns.rcode.REFUSED, dns.rcode.SERVFAIL) or not bool(response.answer)): status = 'NO_ZONE' if zone.serial == 0 and zone.action in ('DELETE', 'NONE'): actual_serial = 0 break # Zone not expected to exist elif response and len(response.answer) == 1 \ and str(response.answer[0].name) == str(zone.name) \ and response.answer[0].rdclass == dns.rdataclass.IN \ and response.answer[0].rdtype == dns.rdatatype.SOA: # parse the SOA response and get the serial number rrset = response.answer[0] actual_serial = list(rrset.to_rdataset().items)[0].serial # TODO(vinod): Account for serial number wrap around. Unix # timestamps are used where Designate is primary, but secondary # zones use different values. if actual_serial is not None and actual_serial >= zone.serial: # Everything looks good at this point. Return SUCCESS. status = 'SUCCESS' break retries_left -= retry_cnt msg = ("Got lower serial for '%(zone)s' to '%(host)s:" "%(port)s'. Expected:'%(es)d'. Got:'%(as)s'." "Retries left='%(retries)d'") % { 'zone': zone.name, 'host': host, 'port': port, 'es': zone.serial, 'as': actual_serial, 'retries': retries_left} if not retries_left: # return with error LOG.warning(msg) break LOG.debug(msg) # retry again time.sleep(retry_interval) # Return retries_left for testing purposes. return status, actual_serial, retries_left
def _make_and_send_dns_message(self, zone, host, port, timeout, retry_interval, max_retries, notify=False): """ Generate and send a DNS message over TCP or UDP using retries and return response. :param zone: The designate zone object. This contains the zone name. :param host: The destination host for the dns message. :param port: The destination port for the dns message. :param timeout: The time (in seconds) to wait for a response from destination. :param retry_interval: The time (in seconds) between retries. :param max_retries: The maximum number of retries mindns would do for a response. After this many retries, the function returns. :param notify: If true, a notify message is constructed else a SOA message is constructed. :return: a tuple of (response, current_retry) where response is the response on success or None on failure. current_retry is the current retry number """ dns_message = self._make_dns_message(zone.name, notify=notify) retry = 0 response = None while retry < max_retries: retry += 1 LOG.info("Sending '%(msg)s' for '%(zone)s' to '%(server)s:" "%(port)d'.", {'msg': 'NOTIFY' if notify else 'SOA', 'zone': zone.name, 'server': host, 'port': port}) try: response = dnsutils.send_dns_message( dns_message, host, port, timeout=timeout ) except socket.error as e: if e.errno != socket.errno.EAGAIN: raise # unknown error, let it traceback # Initial workaround for bug #1558096 LOG.info("Got EAGAIN while trying to send '%(msg)s' for " "'%(zone)s' to '%(server)s:%(port)d'. " "Timeout='%(timeout)d' seconds. Retry='%(retry)d'", {'msg': 'NOTIFY' if notify else 'SOA', 'zone': zone.name, 'server': host, 'port': port, 'timeout': timeout, 'retry': retry}) # retry sending the message time.sleep(retry_interval) continue except dns.exception.Timeout: LOG.warning( "Got Timeout while trying to send '%(msg)s' for " "'%(zone)s' to '%(server)s:%(port)d'. " "Timeout='%(timeout)d' seconds. Retry='%(retry)d'", {'msg': 'NOTIFY' if notify else 'SOA', 'zone': zone.name, 'server': host, 'port': port, 'timeout': timeout, 'retry': retry}) # retry sending the message if we get a Timeout. time.sleep(retry_interval) continue except dns_query.BadResponse: LOG.warning("Got BadResponse while trying to send '%(msg)s' " "for '%(zone)s' to '%(server)s:%(port)d'. " "Timeout='%(timeout)d' seconds. Retry='%(retry)d'", {'msg': 'NOTIFY' if notify else 'SOA', 'zone': zone.name, 'server': host, 'port': port, 'timeout': timeout, 'retry': retry}) break # no retries after BadResponse # either we have a good response or an error that we don't want to # recover by retrying break if not response: return None, retry # Check that we actually got a NOERROR in the rcode and and an # authoritative answer refused_statuses = ( dns.rcode.NXDOMAIN, dns.rcode.REFUSED, dns.rcode.SERVFAIL ) if (response.rcode() in refused_statuses or (response.rcode() == dns.rcode.NOERROR and not bool(response.answer))): if notify: LOG.info( '%(zone)s not found on %(server)s:%(port)d', { 'zone': zone.name, 'server': host, 'port': port } ) elif (not (response.flags & dns.flags.AA) or dns.rcode.from_flags(response.flags, response.ednsflags) != dns.rcode.NOERROR): LOG.warning("Failed to get expected response while trying to " "send '%(msg)s' for '%(zone)s' to '%(server)s:" "%(port)d'.\nResponse message:\n%(resp)s\n", {'msg': 'NOTIFY' if notify else 'SOA', 'zone': zone.name, 'server': host, 'port': port, 'resp': str(response)}) response = None return response, retry def _make_dns_message(self, zone_name, notify=False): """ This constructs a SOA query or a dns NOTIFY message. :param zone_name: The zone name for which a SOA/NOTIFY needs to be sent. :param notify: If true, a notify message is constructed else a SOA message is constructed. :return: The constructed message. """ dns_message = dns.message.make_query(zone_name, dns.rdatatype.SOA) dns_message.flags = 0 if notify: dns_message.set_opcode(dns.opcode.NOTIFY) dns_message.flags |= dns.flags.AA else: # Setting the flags to RD causes BIND9 to respond with a NXDOMAIN. dns_message.set_opcode(dns.opcode.QUERY) dns_message.flags |= dns.flags.RD return dns_message