sven/netbox-plugin-dns-bridge
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Share zone-building logic between AXFR and zone-file export

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export_bind_zone_file diverged from the AXFR path in four ways, each a
bug:

- It iterated nb_zone.records.all(), including inactive records, whereas
  the AXFR handler filtered Record.objects.filter(zone=nb_zone,
  active=True). Exported zone files could contain stale/withdrawn
  records.
- It passed record.ttl straight to rdataset.add(), crashing with a
  TypeError when the NetBox DNS Record had no TTL set. The AXFR path
  used 'ttl = record.ttl or nb_zone.default_ttl'.
- It had no TXT quoting logic, so TXT values containing spaces or
  semicolons were mis-tokenized by dns.rdata.from_text (a ';' was
  treated as the start of a comment). The AXFR path quotes and chunks
  TXT values for exactly this reason.
- It appended a fresh rdataset to the node for every record instead of
  merging records that share a name and type, producing duplicate
  rdatasets and malformed zone files.

Extract build_dns_zone(nb_zone) in utils.py containing the corrected,
AXFR-proven record-building logic (active filter, TTL fallback, TXT
quoting/chunking, rdataset merging via rdatasets_dict). Rewrite
export_bind_zone_file to build the zone through build_dns_zone and then
write it. Rewrite request_handler._get_zone_from_nb to look up the
NetBox DNS Zone and delegate to build_dns_zone, keeping only the
DoesNotExist/OperationalError handling that is specific to the query
path.

Both code paths now produce identical zone data.
This commit is contained in:
Sven Luethi authored and Sven Luthi committed 2026-08-11 18:28:53 +02:00
1 parent c579e49e78
commit 627a3a5712
2 files changed
+88 -98
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netbox_dns_bridge/request_handler.py
+2 -77
View File
@@ -17,6 +17,7 @@ from django.conf import settings
from netbox_dns.models import Zone, Record, View
from netbox_dns_bridge import catalog_zone_manager as catzm
from .models import SeenTransferClients
from .utils import build_dns_zone
LOGGER = get_logger(__name__)
SETTINGS = settings.PLUGINS_CONFIG["netbox_dns_bridge"]
@@ -37,83 +38,7 @@ class DNSBaseRequestHandler(socketserver.BaseRequestHandler):
view__name=view_name,
active=True,
)
# Build DNS zone
zone = dns.zone.Zone(zone_name, dns.name.root)
zone.rdclass = dns.rdataclass.IN
nb_records = Record.objects.filter(zone=nb_zone, active=True)
rdatasets_dict = {}
for record in nb_records:
rdtype = dns.rdatatype.from_text(record.type)
if not record.name:
name = zone.origin
elif record.name.endswith("."):
name = dns.name.from_text(record.name)
else:
name = dns.name.from_text(record.name, origin=zone.origin)
# If the record has no TTL, use the zone default
ttl = record.ttl or nb_zone.default_ttl
# Apply quoting for TXT records to stop tokanizer
# from cutting it up:
value = record.value
if rdtype == dns.rdatatype.TXT:
if value.startswith('"') and value.endswith('"'):
value = value[1:-1].replace('" "', "").replace('"', '"')
if len(value) > 255:
# This is a bug fix for netbox. If netbox allowed for
# an unquoted value to be larger then 255 characters,
# it misunderstood everything behind a ; as a comment.
chunks = [
'"{}"'.format(value[i : i + 255])
for i in range(0, len(value), 255)
]
value = " ".join(chunks)
else:
value = f'"{value}"'
rdata = dns.rdata.from_text(
dns.rdataclass.IN,
rdtype,
value,
relativize=False,
origin=zone.origin,
)
# Initialize rdataset if it doesn't exist for this name and type
if name not in rdatasets_dict:
rdatasets_dict[name] = {}
if rdtype not in rdatasets_dict[name]:
rdatasets_dict[name][rdtype] = dns.rdataset.Rdataset(
dns.rdataclass.IN, rdtype
)
# Add the rdata to the appropriate rdataset
rdatasets_dict[name][rdtype].add(rdata, ttl)
# Now, add all rdatasets to the zone
for name, rdtypes in rdatasets_dict.items():
for rdtype, rdataset in rdtypes.items():
# Ensure rdataset has the same rdclass as the zone
if rdataset.rdclass != zone.rdclass:
raise ValueError(
f"rdataset rdclass {rdataset.rdclass} does not match "
f"zone rdclass {zone.rdclass}"
)
# Check if the rdataset has any rdata before creating an RRset
if not rdataset:
LOGGER.debug(f"Skipping empty rdataset for {name} {rdtype}")
continue # Skip empty rdataset
# Replace the rdataset for the given name and type
zone.replace_rdataset(name, rdataset)
return zone
return build_dns_zone(nb_zone)
except Zone.DoesNotExist:
return None
except OperationalError as e:
netbox_dns_bridge/utils.py
+86 -21
View File
@@ -1,34 +1,99 @@
import dns.name
import dns.zone
import dns.rdatatype
import dns.rdataclass
import dns.exception
import dns.rdataset
import netbox_dns.models
from .logger import get_logger
LOGGER = get_logger(__name__)
def build_dns_zone(nb_zone: netbox_dns.models.Zone) -> dns.zone.Zone:
# Build DNS zone
zone = dns.zone.Zone(nb_zone.name, dns.name.root)
zone.rdclass = dns.rdataclass.IN
nb_records = nb_zone.records.filter(active=True)
rdatasets_dict = {}
for record in nb_records:
rdtype = dns.rdatatype.from_text(record.type)
if not record.name:
name = zone.origin
elif record.name.endswith("."):
name = dns.name.from_text(record.name)
else:
name = dns.name.from_text(record.name, origin=zone.origin)
# If the record has no TTL, use the zone default
ttl = record.ttl or nb_zone.default_ttl
# Apply quoting for TXT records to stop tokanizer
# from cutting it up:
value = record.value
if rdtype == dns.rdatatype.TXT:
if value.startswith('"') and value.endswith('"'):
value = value[1:-1].replace('" "', "").replace('"', '"')
if len(value) > 255:
# This is a bug fix for netbox. If netbox allowed for
# an unquoted value to be larger then 255 characters,
# it misunderstood everything behind a ; as a comment.
chunks = [
'"{}"'.format(value[i : i + 255])
for i in range(0, len(value), 255)
]
value = " ".join(chunks)
else:
value = f'"{value}"'
rdata = dns.rdata.from_text(
dns.rdataclass.IN,
rdtype,
value,
relativize=False,
origin=zone.origin,
)
# Initialize rdataset if it doesn't exist for this name and type
if name not in rdatasets_dict:
rdatasets_dict[name] = {}
if rdtype not in rdatasets_dict[name]:
rdatasets_dict[name][rdtype] = dns.rdataset.Rdataset(
dns.rdataclass.IN, rdtype
)
# Add the rdata to the appropriate rdataset
rdatasets_dict[name][rdtype].add(rdata, ttl)
# Now, add all rdatasets to the zone
for name, rdtypes in rdatasets_dict.items():
for rdtype, rdataset in rdtypes.items():
# Ensure rdataset has the same rdclass as the zone
if rdataset.rdclass != zone.rdclass:
raise ValueError(
f"rdataset rdclass {rdataset.rdclass} does not match "
f"zone rdclass {zone.rdclass}"
)
# Check if the rdataset has any rdata before creating an RRset
if not rdataset:
LOGGER.debug(f"Skipping empty rdataset for {name} {rdtype}")
continue # Skip empty rdataset
# Replace the rdataset for the given name and type
zone.replace_rdataset(name, rdataset)
return zone
def export_bind_zone_file(nb_zone: netbox_dns.models.Zone, file_path: str):
# Create dnspython zone object
dp_zone = dns.zone.Zone(origin=dns.name.from_text(nb_zone.name))
for record in nb_zone.records.all():
rname = record.name or "@"
rdclass = dns.rdataclass.IN
rdatatype = dns.rdatatype.from_text(record.type)
# Create rdata object
rdata = dns.rdata.from_text(rdclass, rdatatype, record.value)
# Create rdataset
rdataset = dns.rdataset.Rdataset(rdclass, rdatatype)
rdataset.add(rdata, record.ttl)
# Add to zone
node = dp_zone.find_node(rname, create=True)
node.rdatasets.append(rdataset)
zone = build_dns_zone(nb_zone)
# Write zone to file in BIND format
try:
with open(file_path, "w") as f:
dp_zone.to_file(f, sorted=True)
zone.to_file(f, sorted=True)
except IOError as e:
raise IOError(f"Failed to write zone file to {file_path}: {e}")