Implement get_subnets_address_scopes method

This patch implement a method to retrieve the IPv4 and IPv6
address scopes of several subnets, providing a list of fixed
IP addresses that belong to a port.

The goal of this patch is to decouple the address scope retrieval
from the logic that determines if an OVN LSP is virtual or not.

Related-Bug: #2018529

Conflicts:
    neutron/common/ovn/utils.py

Change-Id: Id4ab755293627119455cbcd15602690c8ce7a3c1
(cherry picked from commit a22b1de)

Author: ralonsoh

neutron/common/ovn/utils.py

@@ -853,3 +853,45 @@ def get_ovn_chassis_other_config(chassis):
         return chassis.other_config
     except AttributeError:
         return chassis.external_ids
+
+
+def get_subnets_address_scopes(context, subnets, fixed_ips, ml2_plugin):
+    """Returns the IPv4 and IPv6 address scopes of several subnets.
+
+    The subnets hosted on the same network must be allocated from the same
+    subnet pool (from ``NetworkSubnetPoolAffinityError`` exception). That
+    applies per IP version (it means it is possible to have two subnet pools,
+    one for IPv4 and one for IPv6).
+
+    :param context: neutron api request context
+    :param subnets: (list of dict) subnet dictionaries
+    :param fixed_ips: (list of dict) fixed IPs of several subnets (usually
+                      belonging to a network but not mandatory)
+    :param ml2_plugin: (``Ml2Plugin``) ML2 plugin instance
+    :return: (tuple of 2 strings) IPv4 and IPv6 address scope IDs
+    """
+    address4_scope_id, address6_scope_id = '', ''
+    if not subnets:
+        return address4_scope_id, address6_scope_id
+
+    subnets_by_id = {subnet['id']: subnet for subnet in subnets}
+    for fixed_ip in fixed_ips:
+        subnet_id = fixed_ip.get('subnet_id')
+        subnet = subnets_by_id.get(subnet_id)
+        if not subnet or not subnet['subnetpool_id']:
+            continue
+
+        try:
+            subnet_pool = ml2_plugin.get_subnetpool(context,
+                                                    id=subnet['subnetpool_id'])
+            if subnet_pool['address_scope_id']:
+                if subnet_pool['ip_version'] == const.IP_VERSION_4:
+                    address4_scope_id = subnet_pool['address_scope_id']
+                else:
+                    address6_scope_id = subnet_pool['address_scope_id']
+        except n_exc.SubnetPoolNotFound:
+            # swallow the exception and just continue if the
+            # lookup failed
+            pass
+
+    return address4_scope_id, address6_scope_id

neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py

@@ -338,6 +338,9 @@ def _get_port_options(self, port):
             ]
             subnets = self._plugin.get_subnets(
                 context, filters={'id': subnet_ids})
+            address4_scope_id, address6_scope_id = (
+                utils.get_subnets_address_scopes(context, subnets, ip_subnets,
+                                                 self._plugin))
             if subnets:
                 for ip in ip_subnets:
                     ip_addr = ip['ip_address']
@@ -355,26 +358,6 @@ def _get_port_options(self, port):
                                   ip_addr)
                         continue
 
-                    if subnet["subnetpool_id"]:
-                        try:
-                            subnet_pool = self._plugin.get_subnetpool(
-                                context, id=subnet["subnetpool_id"]
-                            )
-                            if subnet_pool["address_scope_id"]:
-                                ip_version = subnet_pool["ip_version"]
-                                if ip_version == const.IP_VERSION_4:
-                                    address4_scope_id = subnet_pool[
-                                        "address_scope_id"
-                                    ]
-                                elif ip_version == const.IP_VERSION_6:
-                                    address6_scope_id = subnet_pool[
-                                        "address_scope_id"
-                                    ]
-                        except n_exc.SubnetPoolNotFound:
-                            # swallow the exception and just continue if the
-                            # lookup failed
-                            pass
-
                     cidrs += ' {}/{}'.format(ip['ip_address'],
                                              subnet['cidr'].split('/')[1])
 

neutron/tests/unit/common/ovn/test_utils.py

@@ -23,6 +23,7 @@
 from neutron_lib.api.definitions import extra_dhcp_opt as edo_ext
 from neutron_lib.api.definitions import portbindings
 from neutron_lib import constants as n_const
+from neutron_lib import exceptions as n_exc
 from oslo_concurrency import processutils
 from oslo_config import cfg
 import testtools
@@ -943,3 +944,62 @@ def test_run_empty_list(self):
     def test_run_bad_schema(self):
         with testtools.ExpectedException(KeyError):
             self.OvsdbClientTestCommand.run(['foo'])
+
+
+class GetSubnetsAddressScopeTestCase(base.BaseTestCase):
+
+    def setUp(self):
+        super().setUp()
+        self.ml2_plugin = mock.Mock()
+
+    def test_no_subnets(self):
+        subnets = []
+        fixed_ips = mock.ANY
+        address4, address6 = utils.get_subnets_address_scopes(
+            mock.ANY, subnets, fixed_ips, self.ml2_plugin)
+        self.assertEqual(('', ''), (address4, address6))
+
+    def test_no_subnetpool(self):
+        subnets = [
+            {'id': 'subnet1', 'subnetpool_id': None},
+            {'id': 'subnet2', 'subnetpool_id': None},
+        ]
+        fixed_ips = [
+            {'subnet_id': 'subnet1'},
+            {'subnet_id': 'subnet2'},
+        ]
+        address4, address6 = utils.get_subnets_address_scopes(
+            mock.ANY, subnets, fixed_ips, self.ml2_plugin)
+        self.assertEqual(('', ''), (address4, address6))
+
+    def test_no_address_scope(self):
+        subnets = [
+            {'id': 'subnet1', 'subnetpool_id': 'pool_ipv4'},
+            {'id': 'subnet2', 'subnetpool_id': 'pool_ipv6'},
+        ]
+        fixed_ips = [
+            {'subnet_id': 'subnet1'},
+            {'subnet_id': 'subnet2'},
+        ]
+        self.ml2_plugin.get_subnetpool.side_effect = n_exc.SubnetPoolNotFound(
+            subnetpool_id='snp')
+        address4, address6 = utils.get_subnets_address_scopes(
+            mock.ANY, subnets, fixed_ips, self.ml2_plugin)
+        self.assertEqual(('', ''), (address4, address6))
+
+    def test_address_scope(self):
+        subnets = [
+            {'id': 'subnet1', 'subnetpool_id': 'pool_ipv4'},
+            {'id': 'subnet2', 'subnetpool_id': 'pool_ipv6'},
+        ]
+        fixed_ips = [
+            {'subnet_id': 'subnet1'},
+            {'subnet_id': 'subnet2'},
+        ]
+        self.ml2_plugin.get_subnetpool.side_effect = [
+            {'address_scope_id': 'scope4', 'ip_version': n_const.IP_VERSION_4},
+            {'address_scope_id': 'scope6', 'ip_version': n_const.IP_VERSION_6},
+        ]
+        address4, address6 = utils.get_subnets_address_scopes(
+            mock.ANY, subnets, fixed_ips, self.ml2_plugin)
+        self.assertEqual(('scope4', 'scope6'), (address4, address6))