netbox-plugin-dns-bridge/netbox_dns_bridge/catalog_zone_manager.py

import dns.name
import dns.zone
import dns.rdatatype
import dns.rdataclass
from .logger import get_logger
from netbox_dns.models import Zone as NBZone
from netbox_dns_bridge.models import IntegerKeyValueSetting, CatalogZoneMemberIdentifier
from uuid import uuid4
from base64 import b32encode
from django.db import transaction, close_old_connections, OperationalError

LOGGER = get_logger(__name__)


def increment_soa_serial() -> int:
    with transaction.atomic():
        try:
            soa_serial_obj = (
                IntegerKeyValueSetting.objects.select_for_update().get_or_create(
                    key="catalog-zone-soa-serial",
                    defaults={"value": 1},
                )
            )

            new_soa_serial = soa_serial_obj.value + 1
            if new_soa_serial > 0xFFFFFFFF:
                LOGGER.warning(
                    f"Catalog serial {soa_serial_obj.value} reached max — wrapping back to 1"
                )
                new_soa_serial = 1
            soa_serial_obj.value = new_soa_serial
            soa_serial_obj.save()
            soa_serial_obj.refresh_from_db()
            LOGGER.debug(
                f"Catalog zone SOA serial number is now {soa_serial_obj.value}"
            )

            return soa_serial_obj.value
        except OperationalError as e:
            LOGGER.error(
                f"ERROR: Failed to increment the Catalog Zone's SOA serial: {e}"
            )
            close_old_connections()


def create_zone(name, view_name) -> dns.zone.Zone:
    # Zone origin
    origin = dns.name.from_text(name, dns.name.root)

    # Create a new empty zone
    zone = dns.zone.Zone(origin)
    zone.rdclass = dns.rdataclass.IN

    try:
        # get zones from netbox
        nb_zones = NBZone.objects.filter(
            view__name=view_name, active=True
        ).select_related("catz_identifier")

        ptr_base = dns.name.from_text("zones", origin)

        for nb_zone in nb_zones:
            ttl = 0
            qname = dns.name.from_text(nb_zone.name, dns.name.root)

            # Create PTR record
            try:
                catz_identifier = nb_zone.catz_identifier
            except NBZone.catz_identifier.RelatedObjectDoesNotExist:
                catz_identifier = CatalogZoneMemberIdentifier.objects.create(
                    zone=nb_zone, name=_generate_member_identifier()
                )

            p_name = catz_identifier.name

            ptr_name = dns.name.from_text(p_name, ptr_base)
            if not ptr_name.is_subdomain(origin):
                raise ValueError(
                    f"Catalog zone member identifier {ptr_name.to_text()} not a subdomain"
                )
            rdata = dns.rdata.from_text(
                dns.rdataclass.IN, dns.rdatatype.PTR, qname.to_text()
            )
            rdataset = zone.find_rdataset(ptr_name, dns.rdatatype.PTR, create=True)
            rdataset.add(rdata, ttl)

            # Configure DNSSec Policy for member Zone if DNSSec is enabled
            if nb_zone.dnssec_policy:
                rid = dns.name.from_text("group", ptr_name)
                policy_name = nb_zone.dnssec_policy.name.rstrip(" ")
                group_name = f"dnssec-policy-{policy_name}"
                rdata = dns.rdata.from_text(
                    dns.rdataclass.IN, dns.rdatatype.TXT, group_name
                )
                rdataset = zone.find_rdataset(rid, dns.rdatatype.TXT, create=True)
                rdataset.add(rdata, ttl)

        zone_root_node = zone.find_node(origin, create=True)

        # SOA record
        soa_rdataset = _create_soa_rdataset()
        zone_root_node.rdatasets.append(soa_rdataset)

        # NS record
        ns_rdataset = _create_ns_rdataset()
        zone_root_node.rdatasets.append(ns_rdataset)

        # version.catz. record
        version_rdataset = _create_version_rdataset()
        zone_version_node = zone.find_node(
            dns.name.from_text("version", origin), create=True
        )
        zone_version_node.rdatasets.append(version_rdataset)

        return zone

    except OperationalError as e:
        LOGGER.error(f"ERROR: Failed to create Catalog Zone: {e}")
        close_old_connections()
        return None


def _generate_member_identifier() -> str:
    return b32encode(uuid4().bytes)[0:26].lower().decode("UTF-8")


def update_member_identifier(zone: NBZone) -> None:
    try:
        CatalogZoneMemberIdentifier.objects.update_or_create(
            zone=zone,
            defaults={"name": _generate_member_identifier()},
        )
    except OperationalError as e:
        LOGGER.error(f"ERROR: Failed to update Catalog Zone member identifier: {e}")
        close_old_connections()


def _create_soa_rdataset() -> dns.rdataset:
    try:
        serial = IntegerKeyValueSetting.objects.get_or_create(
            key="catalog-zone-soa-serial", defaults={"value": 1}
        ).value

        # SOA Record components
        ttl = 0
        rclass = dns.rdataclass.IN
        rtype = dns.rdatatype.SOA

        # Create SOA rdata object
        rdata = dns.rdata.from_text(
            rclass,
            rtype,
            f"invalid. invalid. {serial} 60 10 1209600 0",
        )

        # Create Rdataset and add the RDATA to it
        rdataset = dns.rdataset.Rdataset(rclass, rtype)
        rdataset.add(rdata, ttl)
        return rdataset

    except OperationalError as e:
        LOGGER.error(f"ERROR: Failed to access catz SOA record in database: {e}")
        close_old_connections()


def _create_ns_rdataset() -> dns.rdataset:
    # NS record for catz.
    name = dns.name.from_text("invalid", dns.name.root)
    rdata = dns.rdata.from_text(dns.rdataclass.IN, dns.rdatatype.NS, str(name))
    rdataset = dns.rdataset.Rdataset(dns.rdataclass.IN, dns.rdatatype.NS)
    rdataset.add(rdata, 0)
    return rdataset


def _create_version_rdataset() -> dns.rdataset:
    rdata = dns.rdata.from_text(dns.rdataclass.IN, dns.rdatatype.TXT, '"2"')
    rdataset = dns.rdataset.Rdataset(dns.rdataclass.IN, dns.rdatatype.TXT)
    rdataset.add(rdata, 0)
    return rdataset