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# DHCPy6d DHCPv6 Daemon
#
# Copyright (C) 2009-2022 Henri Wahl <henri@dhcpy6d.de>
#
# This program 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 program 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 program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
import copy
from dns.resolver import (NoAnswer,
NoNameservers)
from .config import cfg
from .globals import (dns_query_queue,
resolver_query)
from .helpers import decompress_ip6
from .storage import volatile_store
def dns_update(transaction, action='update'):
"""
update DNS entries on specified nameserver
at the moment this only works with Bind
uses all addresses of client if they want to be dynamically updated
regarding RFC 4704 5. there are 3 kinds of client behaviour for N O S:
- client wants to update DNS itself -> sends 0 0 0
- client wants server to update DNS -> sends 0 0 1
- client wants no server DNS update -> sends 1 0 0
"""
if transaction.client:
# if allowed use client supplied hostname, otherwise that from config
if cfg.DNS_USE_CLIENT_HOSTNAME:
# hostname from transaction
hostname = transaction.hostname
else:
# hostname from client info built from configuration
hostname = transaction.client.hostname
# if address should be updated in DNS update it
for a in transaction.client.addresses:
if a.DNS_UPDATE and hostname != '' and a.VALID:
if cfg.DNS_IGNORE_CLIENT or transaction.dns_s == 1:
# put query into DNS query queue
dns_query_queue.put((action, hostname, a))
return True
else:
return False
def dns_delete(transaction, address='', action='release'):
"""
delete DNS entries on specified nameserver
at the moment this only works with ISC Bind
"""
hostname, duid, mac, iaid = volatile_store.get_host_lease(address)
# if address should be updated in DNS update it
# local flag to check if address should be deleted from DNS
delete = False
for a in list(cfg.ADDRESSES.values()):
# if there is any address type which prototype matches use its DNS ZONE
if a.matches_prototype(address):
# kind of RCF-compliant security measure - check if hostname and DUID from transaction fits them of store
if duid == transaction.duid and \
iaid == transaction.iaid:
delete = True
# also check MAC address if MAC counts in general - not RFCish
if 'mac' in cfg.IDENTIFICATION:
if not mac == transaction.mac:
delete = False
if hostname != '' and delete:
# use address from address types as template for the real
# address to be deleted from DNS
dns_address = copy.copy(a)
dns_address.ADDRESS = address
# put query into DNS query queue
dns_query_queue.put((action, hostname, dns_address))
# enough
break
def get_ip_from_dns(hostname):
"""
Get IPv6 address from DNS for address category 'dns'
"""
try:
answer = resolver_query.query(hostname, 'AAAA')
return decompress_ip6(answer.rrset.to_text().split(' ')[-1])
except NoAnswer:
return False
except NoNameservers:
return False
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