Merge ~blake-rouse/maas:fix-1830103 into maas:master

[Blake Rouse]

Fixes LP: #1830103 - Update StaticIPAddress subnet links for when a subnet is created or updated where that IP address now falls with in that subnet CIDR.

[Newell Jensen (newell-jensen)]

Looks good.

review: Approve

[MAAS Lander (maas-lander)]

LANDING
-b fix-1830103 lp:~blake-rouse/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci-jenkins.internal:8080/job/maas/job/branch-tester/5746/consoleText

diff --git a/src/maasserver/models/signals/__init__.py b/src/maasserver/models/signals/__init__.py
index 4f020cd..2f6c1b9 100644
--- a/src/maasserver/models/signals/__init__.py
+++ b/src/maasserver/models/signals/__init__.py
@@ -22,6 +22,7 @@ __all__ = [
     "scriptresult",
     "services",
     "staticipaddress",
+    "subnet",
 ]
 
 from maasserver.models.signals import (
@@ -43,4 +44,5 @@ from maasserver.models.signals import (
     scriptresult,
     services,
     staticipaddress,
+    subnet,
 )
diff --git a/src/maasserver/models/signals/subnet.py b/src/maasserver/models/signals/subnet.py
new file mode 100644
index 0000000..e32dfde
--- /dev/null
+++ b/src/maasserver/models/signals/subnet.py
@@ -0,0 +1,55 @@
+# Copyright 2019 Canonical Ltd.  This software is licensed under the
+# GNU Affero General Public License version 3 (see the file LICENSE).
+
+"""Respond to Subnet CIDR changes."""
+
+__all__ = [
+    "signals",
+]
+
+from django.db.models.signals import post_save
+from maasserver.enum import IPADDRESS_TYPE
+from maasserver.models import (
+    StaticIPAddress,
+    Subnet,
+)
+from maasserver.utils.signals import SignalsManager
+
+
+signals = SignalsManager()
+
+
+def update_referenced_ip_addresses(subnet):
+    """Updates the `StaticIPAddress`'s to ensure that they are linked to the
+    correct subnet."""
+
+    # Remove the IP addresses that no longer fall with in the CIDR.
+    remove_ips = StaticIPAddress.objects.filter(
+        alloc_type=IPADDRESS_TYPE.USER_RESERVED, subnet_id=subnet.id)
+    remove_ips = remove_ips.extra(
+        where=['NOT(ip << %s)'], params=[subnet.cidr])
+    remove_ips.update(subnet=None)
+
+    # Add the IP addresses that now fall into CIDR.
+    add_ips = StaticIPAddress.objects.filter(subnet__isnull=True)
+    add_ips = add_ips.extra(
+        where=['ip << %s'], params=[subnet.cidr])
+    add_ips.update(subnet_id=subnet.id)
+
+
+def post_created(sender, instance, created, **kwargs):
+    if created:
+        update_referenced_ip_addresses(instance)
+
+
+def updated_cidr(instance, old_values, **kwargs):
+    update_referenced_ip_addresses(instance)
+
+
+signals.watch(
+    post_save, post_created, sender=Subnet)
+signals.watch_fields(
+    updated_cidr, Subnet, ['cidr'], delete=False)
+
+# Enable all signals by default.
+signals.enable()
diff --git a/src/maasserver/models/signals/tests/test_subnet.py b/src/maasserver/models/signals/tests/test_subnet.py
new file mode 100644
index 0000000..200acf7
--- /dev/null
+++ b/src/maasserver/models/signals/tests/test_subnet.py
@@ -0,0 +1,66 @@
+# Copyright 2019 Canonical Ltd.  This software is licensed under the
+# GNU Affero General Public License version 3 (see the file LICENSE).
+
+"""Test the behaviour of subnet signals."""
+
+__all__ = []
+
+from maasserver.enum import IPADDRESS_TYPE
+from maasserver.testing.factory import factory
+from maasserver.testing.testcase import MAASServerTestCase
+
+
+class TestSubnetSignals(MAASServerTestCase):
+
+    scenarios = (
+        ('ipv4', {
+            'network_maker': factory.make_ipv4_network,
+        }),
+        ('ipv6', {
+            'network_maker': factory.make_ipv6_network,
+        }),
+    )
+
+    def test_creating_subnet_links_to_existing_ip_address(self):
+        network = self.network_maker()
+        ip = factory.pick_ip_in_network(network)
+        ip_address = factory.make_StaticIPAddress(
+            ip=ip, alloc_type=IPADDRESS_TYPE.USER_RESERVED)
+
+        # Ensure that for this test to really be testing the logic the
+        # `StaticIPAddress` needs to not have a subnet assigned.
+        self.assertIsNone(ip_address.subnet)
+
+        # Creating the subnet, must link the created `StaticIPAddress` to
+        # that subnet.
+        subnet = factory.make_Subnet(cidr=network.cidr)
+        ip_address.refresh_from_db()
+        self.assertEqual(subnet, ip_address.subnet)
+
+    def test_updating_subnet_removes_existing_ip_address_adds_another(self):
+        network1 = self.network_maker()
+        network2 = self.network_maker(but_not=network1)
+        ip1 = factory.pick_ip_in_network(network1)
+        ip2 = factory.pick_ip_in_network(network2)
+
+        # Create the second IP address not linked to network2.
+        ip_address2 = factory.make_StaticIPAddress(
+            ip=ip2, alloc_type=IPADDRESS_TYPE.USER_RESERVED)
+        self.assertIsNone(ip_address2.subnet)
+
+        # Create the first IP address assigned to the network.
+        subnet = factory.make_Subnet(cidr=network1.cidr)
+        ip_address1 = factory.make_StaticIPAddress(
+            ip=ip1, alloc_type=IPADDRESS_TYPE.USER_RESERVED, subnet=subnet)
+        self.assertEqual(subnet, ip_address1.subnet)
+
+        # Update the subnet to have the CIDR of network2.
+        subnet.cidr = network2.cidr
+        subnet.gateway_ip = None
+        subnet.save()
+
+        # IP1 should not have a subnet, and IP2 should not have the subnet.
+        ip_address1.refresh_from_db()
+        ip_address2.refresh_from_db()
+        self.assertIsNone(ip_address1.subnet)
+        self.assertEqual(subnet, ip_address2.subnet)