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 time

import dns
import dns.rdataclass
import dns.rdatatype
import dns.exception
import dns.query
import dns.flags
import dns.rcode
import dns.message
import dns.opcode
from oslo import messaging
from oslo.config import cfg
from oslo_log import log as logging

from designate.pool_manager import rpcapi as pool_mngr_api
from designate.central import rpcapi as central_api
from designate.mdns import xfr
from designate.i18n import _LI
from designate.i18n import _LW

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


[docs]class NotifyEndpoint(xfr.XFRMixin): RPC_NOTIFY_API_VERSION = '1.1' target = messaging.Target( namespace='notify', version=RPC_NOTIFY_API_VERSION) def __init__(self, tg, *args, **kwargs): LOG.info(_LI("started mdns notify endpoint")) self.tg = tg @property
[docs] def central_api(self): return central_api.CentralAPI.get_instance()
@property
[docs] def pool_manager_api(self): return pool_mngr_api.PoolManagerAPI.get_instance()
[docs] def notify_zone_changed(self, context, domain, server, timeout, retry_interval, max_retries, delay): """ :param context: The user context. :param domain: The designate domain object. This contains the domain name. :param server: A notify is sent to server.host:server.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. """ time.sleep(delay) return self._make_and_send_dns_message( domain, server, timeout, retry_interval, max_retries, notify=True)
[docs] def poll_for_serial_number(self, context, domain, server, timeout, retry_interval, max_retries, delay): """ :param context: The user context. :param domain: The designate domain object. This contains the domain name. domain.serial = expected_serial :param server: server.host:server.port is checked for an updated serial number. :param timeout: The time (in seconds) to wait for a SOA response from server. :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: The pool manager is informed of the status with update_status. """ (status, actual_serial, retries) = self.get_serial_number( context, domain, server, timeout, retry_interval, max_retries, delay) self.pool_manager_api.update_status( context, domain, server, status, actual_serial)
[docs] def get_serial_number(self, context, domain, server, timeout, retry_interval, max_retries, delay): """ :param context: The user context. :param domain: The designate domain object. This contains the domain name. domain.serial = expected_serial :param server: server.host:server.port is checked for an updated serial number. :param timeout: The time (in seconds) to wait for a SOA response from server. :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 server 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 = max_retries time.sleep(delay) while (True): (response, retry) = self._make_and_send_dns_message( domain, server, timeout, retry_interval, retries) if response and response.rcode() in ( dns.rcode.NXDOMAIN, dns.rcode.REFUSED, dns.rcode.SERVFAIL): status = 'NO_DOMAIN' elif response and len(response.answer) == 1 \ and str(response.answer[0].name) == str(domain.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 = rrset.to_rdataset().items[0].serial if actual_serial is None: break # TODO(vinod): Account for serial number wrap around. elif actual_serial < domain.serial: retries = retries - retry LOG.warn(_LW("Got lower serial for '%(zone)s' to '%(host)s:" "%(port)s'. Expected:'%(es)d'. Got:'%(as)d'." "Retries left='%(retries)d'") % {'zone': domain.name, 'host': server.host, 'port': server.port, 'es': domain.serial, 'as': actual_serial, 'retries': retries}) if retries > 0: # retry again time.sleep(retry_interval) continue else: break else: # Everything looks good at this point. Return SUCCESS. status = 'SUCCESS' break # Return retries for testing purposes. return (status, actual_serial, retries)
def _make_and_send_dns_message(self, domain, server, timeout, retry_interval, max_retries, notify=False): """ :param domain: The designate domain object. This contains the domain name. :param server: The destination for the dns message is server.host:server.port. :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 """ dest_ip = server.host dest_port = server.port dns_message = self._make_dns_message(domain.name, notify=notify) retry = 0 response = None while retry < max_retries: retry = retry + 1 LOG.info(_LI("Sending '%(msg)s' for '%(zone)s' to '%(server)s:" "%(port)d'.") % {'msg': 'NOTIFY' if notify else 'SOA', 'zone': domain.name, 'server': dest_ip, 'port': dest_port}) response = self._send_dns_message( dns_message, dest_ip, dest_port, timeout) if isinstance(response, dns.exception.Timeout): LOG.warn(_LW("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': domain.name, 'server': dest_ip, 'port': dest_port, 'timeout': timeout, 'retry': retry}) response = None # retry sending the message if we get a Timeout. time.sleep(retry_interval) continue elif isinstance(response, dns.query.BadResponse): LOG.warn(_LW("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': domain.name, 'server': dest_ip, 'port': dest_port, 'timeout': timeout, 'retry': retry}) response = None break # Check that we actually got a NOERROR in the rcode and and an # authoritative answer elif response.rcode() in (dns.rcode.NXDOMAIN, dns.rcode.REFUSED, dns.rcode.SERVFAIL): LOG.info(_LI("%(zone)s not found on %(server)s:%(port)d") % {'zone': domain.name, 'server': dest_ip, 'port': dest_port}) break elif not (response.flags & dns.flags.AA) or dns.rcode.from_flags( response.flags, response.ednsflags) != dns.rcode.NOERROR: LOG.warn(_LW("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': domain.name, 'server': dest_ip, 'port': dest_port, 'resp': str(response)}) response = None break else: break 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) else: # Setting the flags to RD causes BIND9 to respond with a NXDOMAIN. dns_message.flags = dns.flags.RD dns_message.set_opcode(dns.opcode.QUERY) return dns_message def _send_dns_message(self, dns_message, dest_ip, dest_port, timeout): """ :param dns_message: The dns message that needs to be sent. :param dest_ip: The destination ip of dns_message. :param dest_port: The destination port of dns_message. :param timeout: The timeout in seconds to wait for a response. :return: response or dns.exception.Timeout or dns.query.BadResponse """ try: if not CONF['service:mdns'].all_tcp: response = dns.query.udp( dns_message, dest_ip, port=dest_port, timeout=timeout) else: response = dns.query.tcp( dns_message, dest_ip, port=dest_port, timeout=timeout) return response except dns.exception.Timeout as timeout: return timeout except dns.query.BadResponse as badResponse: return badResponse

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