Files
netbox-plugin-dns-bridge/netbox_dns_bridge/notify_handler.py
T
sven 41d409658c Fix NOTIFY missing SOA serial by placing SOA in answer section
RFC 1996 section 3.10 requires the SOA RR carrying the new zone serial
to be placed in the answer section of a NOTIFY message. BIND9's notify
processing looks for the SOA there and, when it is absent, logs that the
NOTIFY does not contain a SOA serial.

Both SendClientDNSNotify and SendNSNotify were appending the SOA RRset
to the authority section instead of the answer section, which is why
BIND9 reported the missing serial. Move the append to msg.answer in both
handlers so receivers can correctly extract the new serial.
2026-08-11 12:34:12 +02:00

264 lines
9.3 KiB
Python

import dns.message
import dns.name
import dns.opcode
import dns.query
import dns.rdatatype
import dns.rdataclass
import dns.rrset
import dns.tsig
from django.conf import settings
from django.utils import timezone
from django.db import close_old_connections, OperationalError
from netbox.jobs import JobRunner
from netbox_dns.models import View, Zone, Record
from .logger import get_logger
from .models import SeenTransferClients, IntegerKeyValueSetting
LOGGER = get_logger(__name__)
SETTINGS = settings.PLUGINS_CONFIG["netbox_dns_bridge"]
def _load_tsig_key(view_name: str) -> dns.tsig.Key:
tsig_keys = SETTINGS.get("tsig_keys", {})
if view_name not in tsig_keys:
raise RuntimeError(f"No TSIG key configured for view '{view_name}'")
key_data = tsig_keys[view_name]
raw_key_name = key_data.get("keyname")
secret = key_data.get("secret")
algorithm = key_data.get("algorithm")
if not algorithm:
raise RuntimeError(
f"Missing 'algorithm' in TSIG key configuration for view '{view_name}'"
)
if not raw_key_name or not secret:
raise RuntimeError(f"Incomplete TSIG key configuration for view '{view_name}'")
key_name = dns.name.from_text(raw_key_name, origin=None).canonicalize()
if not key_name.is_absolute():
key_name = key_name.concatenate(dns.name.root)
return dns.tsig.Key(name=key_name, secret=secret, algorithm=algorithm)
class SendClientDNSNotify(JobRunner):
class Meta:
name = "Send DNS NOTIFY"
def run(self, *args, **kwargs):
notify_over_tcp = SETTINGS.get("notify_over_tcp", False)
port = SETTINGS.get("notify_client_port", 53)
view_name = kwargs["view_name"]
try:
catz_serial = IntegerKeyValueSetting.objects.get(
key="catalog-zone-soa-serial"
).value
zones = [
(kwargs["zone_name"], kwargs["soa_serial"]),
("catz", catz_serial),
(f"{view_name}.catz", catz_serial),
]
view = View.objects.get(name=view_name)
tsig_key = _load_tsig_key(view_name)
cutoff_hours = SETTINGS.get("notify_client_alive_threshold_hours", 24)
seen_cutoff = timezone.now() - timezone.timedelta(hours=cutoff_hours)
clients = SeenTransferClients.objects.filter(
view=view, last_seen__gte=seen_cutoff
)
for zone_name, soa_serial in zones:
zone_name = dns.name.from_text(zone_name, dns.name.root).to_text()
msg = dns.message.make_query(zone_name, dns.rdatatype.SOA)
msg.flags |= dns.flags.AA # = 0
msg.set_opcode(dns.opcode.NOTIFY)
soa_rdata = dns.rdata.from_text(
dns.rdataclass.IN,
dns.rdatatype.SOA,
f"invalid. invalid. {soa_serial} 60 10 1209600 0",
)
soa_rrset = dns.rrset.from_rdata(zone_name, 0, soa_rdata)
msg.answer.append(soa_rrset)
msg.use_tsig(keyring={tsig_key.name: tsig_key}, keyname=tsig_key.name)
for client in clients:
try:
if notify_over_tcp:
LOGGER.debug("Sending NOTIFY over TCP")
dns.query.tcp(msg, client.source_ip, port=port, timeout=2)
else:
LOGGER.debug("Sending NOTIFY over UDP")
dns.query.udp(msg, client.source_ip, port=port, timeout=2)
LOGGER.info(
f"NOTIFY sent: {client.source_ip} {view_name}/{zone_name} {soa_serial}"
)
except Exception as e:
LOGGER.error(
f"NOTIFY failed: {client.source_ip}:{port}"
f" {view_name}/{zone_name} {soa_serial}: {e}"
)
except IntegerKeyValueSetting.DoesNotExist as e:
LOGGER.error(f"Failed to get catalog zone serial: {e}")
except OperationalError as e:
LOGGER.error(f"NOTIFY failed due to unexpected error: {e}")
close_old_connections()
class SendNSNotify(JobRunner):
"""Send a NOTIFY straight to a zone's own nameservers.
Unlike ``SendClientDNSNotify`` (which notifies clients that previously queried the
transfer endpoint), this job resolves the addresses of the zone's configured
nameservers from NetBox DNS itself and notifies each of them so they pick up
the changed zone quickly.
"""
class Meta:
name = "Send DNS NOTIFY to zone nameservers"
def run(self, *args, **kwargs):
notify_over_tcp = SETTINGS.get("notify_over_tcp", False)
port = SETTINGS.get("notify_ns_port", 53)
view_name = kwargs["view_name"]
zone_name = kwargs["zone_name"]
soa_serial = kwargs["soa_serial"]
try:
zone = Zone.objects.get(pk=kwargs["zone_id"])
except Zone.DoesNotExist:
LOGGER.error(f"NS NOTIFY: zone id {kwargs['zone_id']} no longer exists")
return
except OperationalError as e:
LOGGER.error(f"NS NOTIFY failed due to unexpected error: {e}")
close_old_connections()
return
ns_targets = _resolve_zone_nameserver_ips(zone)
if not ns_targets:
LOGGER.warning(
f"NS NOTIFY: no nameserver addresses found in NetBox DNS for "
f"{view_name}/{zone_name} — skipping"
)
return
try:
tsig_key = _load_tsig_key(view_name)
except RuntimeError as e:
LOGGER.error(f"NS NOTIFY aborted for {view_name}/{zone_name}: {e}")
return
fqdn = dns.name.from_text(zone_name, dns.name.root).to_text()
msg = dns.message.make_query(fqdn, dns.rdatatype.SOA)
msg.flags |= dns.flags.AA
msg.set_opcode(dns.opcode.NOTIFY)
soa_rdata = dns.rdata.from_text(
dns.rdataclass.IN,
dns.rdatatype.SOA,
f"invalid. invalid. {soa_serial} 60 10 1209600 0",
)
msg.answer.append(dns.rrset.from_rdata(fqdn, 0, soa_rdata))
msg.use_tsig(keyring={tsig_key.name: tsig_key}, keyname=tsig_key.name)
for ip in ns_targets:
try:
if notify_over_tcp:
LOGGER.debug("Sending NS NOTIFY over TCP")
dns.query.tcp(msg, ip, port=port, timeout=2)
else:
LOGGER.debug("Sending NS NOTIFY over UDP")
dns.query.udp(msg, ip, port=port, timeout=2)
LOGGER.info(f"NS NOTIFY sent: {ip} {view_name}/{fqdn} {soa_serial}")
except Exception as e:
LOGGER.error(
f"NS NOTIFY failed: {ip} {view_name}/{fqdn} {soa_serial}: {e}"
)
def _get_soa_serial(zone: Zone):
"""Return the current SOA serial of a zone parsed from its SOA record."""
try:
soa_record = Record.objects.filter(zone=zone, type="SOA", active=True).first()
if soa_record is None:
LOGGER.error(f"Zone {zone.name} has no active SOA record — skipping NOTIFY")
return None
return int(soa_record.value.split()[2])
except OperationalError as e:
LOGGER.error(f"DB ERROR while fetching SOA for zone {zone.name}: {e}")
close_old_connections()
return None
except (ValueError, IndexError) as e:
LOGGER.error(f"Failed to parse SOA serial for zone {zone.name}: {e}")
return None
def _resolve_zone_nameserver_ips(zone: Zone) -> list:
"""Resolve the zone's nameserver hostnames to IPs using NetBox DNS records.
For each nameserver assigned to the zone, matching active A/AAAA records
within the same view are looked up in NetBox DNS. Returns a de-duplicated,
order-preserving list of IP addresses.
"""
ips = []
try:
nameservers = list(zone.nameservers.all())
view = zone.view
for nameserver in nameservers:
fqdn = dns.name.from_text(nameserver.name, dns.name.root).to_text()
# Match both with and without a trailing dot to be resilient against
# how the fqdn is stored on the Record model.
candidates = {fqdn, fqdn.rstrip(".")}
records = Record.objects.filter(
fqdn__in=list(candidates),
type__in=["A", "AAAA"],
active=True,
zone__view=view,
)
for record in records:
if record.value not in ips:
ips.append(record.value)
except OperationalError as e:
LOGGER.error(f"DB ERROR while resolving nameservers for {zone.name}: {e}")
close_old_connections()
return ips
def schedule_client_notify(zone: Zone):
soa_serial = _get_soa_serial(zone)
if soa_serial is None:
return
SendClientDNSNotify.enqueue(
zone_name=zone.name,
view_name=zone.view.name,
soa_serial=soa_serial,
)
def schedule_ns_notify(zone: Zone):
soa_serial = _get_soa_serial(zone)
if soa_serial is None:
return
SendNSNotify.enqueue(
zone_id=zone.pk,
zone_name=zone.name,
view_name=zone.view.name,
soa_serial=soa_serial,
)