Add RFC 2317 classless reverse zone names for sub-/24 subnets

tests/test_models.py

@@ -0,0 +1,37 @@
+import pytest
+
+from mdb.models import Ip4Subnet, Ip6Subnet
+
+
+@pytest.mark.parametrize(
+    "network,netmask,expected",
+    [
+        # /24 and shorter -> standard octet-boundary name
+        ("203.0.113.0", "255.255.255.0", "113.0.203.in-addr.arpa"),
+        ("10.0.3.0", "255.255.255.0", "3.0.10.in-addr.arpa"),
+        ("10.0.0.0", "255.255.0.0", "0.0.10.in-addr.arpa"),
+        # longer than /24 -> RFC 2317 classless name
+        ("192.0.2.192", "255.255.255.192", "192-26.2.0.192.in-addr.arpa"),
+        ("10.0.0.0", "255.255.255.252", "0-30.0.0.10.in-addr.arpa"),
+        ("10.1.2.0", "255.255.255.128", "0-25.2.1.10.in-addr.arpa"),
+        # host bits set -> normalized down to the network address
+        ("192.0.2.200", "255.255.255.192", "192-26.2.0.192.in-addr.arpa"),
+    ],
+)
+def test_ip4_reverse_zone_name(network, netmask, expected):
+    subnet = Ip4Subnet(network=network, netmask=netmask)
+    assert subnet.reverse_zone_name == expected
+
+
+@pytest.mark.parametrize(
+    "network,netmask,expected",
+    [
+        ("2001:db8", 64, "0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa"),
+        ("2001:db8", 48, "0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa"),
+        ("2001:db8:abcd", 56, "0.0.d.c.b.a.8.b.d.0.1.0.0.2.ip6.arpa"),
+        ("2001:db8", 32, "8.b.d.0.1.0.0.2.ip6.arpa"),
+    ],
+)
+def test_ip6_reverse_zone_name(network, netmask, expected):
+    subnet = Ip6Subnet(network=network, netmask=netmask)
+    assert subnet.reverse_zone_name == expected

tests/test_signals.py

@@ -0,0 +1,67 @@
+import pytest
+
+from mdb.models import DhcpConfig, Ip4Subnet, Ip6Subnet
+
+# ---------------------------------------------------------------------------
+# pre_save signals: populate domain_name once, then leave it frozen
+# ---------------------------------------------------------------------------
+
+
+def make_ip4subnet(**overrides):
+    dhcp_config = DhcpConfig.objects.create(serial=1, active_serial=1)
+    fields = {
+        "name": "test-subnet",
+        "netmask": "255.255.255.192",
+        "network": "192.0.2.192",
+        "domain_soa": "ns1.example.org",
+        "domain_admin": "admin@example.org",
+        "domain_filename": "db.test-subnet",
+        "dhcp_config": dhcp_config,
+    }
+    fields.update(overrides)
+    return Ip4Subnet.objects.create(**fields)
+
+
+@pytest.mark.django_db
+def test_ip4_signal_sets_classless_domain_name():
+    subnet = make_ip4subnet()
+    assert subnet.domain_name == "192-26.2.0.192.in-addr.arpa"
+
+
+@pytest.mark.django_db
+def test_ip4_signal_sets_plain_domain_name_for_slash24():
+    subnet = make_ip4subnet(network="203.0.113.0", netmask="255.255.255.0")
+    assert subnet.domain_name == "113.0.203.in-addr.arpa"
+
+
+@pytest.mark.django_db
+def test_ip4_signal_does_not_overwrite_existing_domain_name():
+    subnet = make_ip4subnet(domain_name="manual.in-addr.arpa")
+    assert subnet.domain_name == "manual.in-addr.arpa"
+
+
+@pytest.mark.django_db
+def test_ip4_domain_name_is_frozen_when_network_changes():
+    subnet = make_ip4subnet()
+    assert subnet.domain_name == "192-26.2.0.192.in-addr.arpa"
+
+    subnet.network = "10.0.0.0"
+    subnet.netmask = "255.255.255.0"
+    subnet.save()
+    subnet.refresh_from_db()
+
+    # The name is derived once and then left alone.
+    assert subnet.domain_name == "192-26.2.0.192.in-addr.arpa"
+
+
+@pytest.mark.django_db
+def test_ip6_signal_sets_domain_name():
+    subnet = Ip6Subnet.objects.create(
+        name="ipv6-doc",
+        network="2001:db8",
+        netmask=64,
+        domain_soa="ns1.example.org",
+        domain_admin="admin@example.org",
+        domain_filename="db.reverse-v6",
+    )
+    assert subnet.domain_name == "0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa"