Get ips from system dns resolver without scope

Currently, is_valid_ipv6 accepts ipv6 addresses with scope. However
netaddr library won't accept an address with scope. Now,
get_noscope_ipv6() can be used to avoid this situation. In a future we
will be able to use the same function which is also being defined on
oslo.utils. https://review.opendev.org/c/openstack/oslo.utils/+/925469

Closes-Bug: #2073894
Signed-off-by: Elvira García <egarciar@redhat.com>
Change-Id: I27f25f90c54d7aaa3c4a7b5317b4b8a4122e4068

neutron/common/ipv6_utils.py

@@ -16,6 +16,8 @@
 """
 IPv6-related utilities and helper functions.
 """
+import ipaddress
+
 import netaddr
 from neutron_lib import constants as const
 from oslo_log import log
@@ -56,3 +58,19 @@ def valid_ipv6_url(host, port):
     else:
         uri = '%s:%s' % (host, port)
     return uri
+
+
+# TODO(egarciar): Remove and use oslo.utils version of this function whenever
+# it is available for Neutron.
+# https://review.opendev.org/c/openstack/oslo.utils/+/925469
+def get_noscope_ipv6(address):
+    try:
+        _ipv6 = ipaddress.IPv6Address(address)
+        if _ipv6.scope_id:
+            address = address.removesuffix('%' + _ipv6.scope_id)
+        return address
+    except (ipaddress.AddressValueError, AttributeError):
+        if netutils.is_valid_ipv6(address):
+            parts = address.rsplit("%", 1)
+            return parts[0]
+        raise

neutron/common/ovn/utils.py

@@ -44,6 +44,7 @@ import tenacity
 
 from neutron._i18n import _
 from neutron.common import _constants as n_const
+from neutron.common import ipv6_utils
 from neutron.common.ovn import constants
 from neutron.common.ovn import exceptions as ovn_exc
 from neutron.common import utils as common_utils
@@ -675,6 +676,8 @@ def get_system_dns_resolvers(resolver_file=DNS_RESOLVER_FILE):
             valid_ip = (netutils.is_valid_ipv4(line, strict=True) or
                         netutils.is_valid_ipv6(line))
             if valid_ip:
+                if netutils.is_valid_ipv6(line):
+                    line = ipv6_utils.get_noscope_ipv6(line)
                 resolvers.append(line)
 
     return resolvers

neutron/tests/unit/common/test_ipv6_utils.py

@@ -98,3 +98,16 @@ class TestValidIpv6URL(base.BaseTestCase):
         port = 443
         self.assertEqual("controller:443",
                          ipv6_utils.valid_ipv6_url(host, port))
+
+
+class TestNoscopeIpv6(base.BaseTestCase):
+    def test_get_noscope_ipv6(self):
+        self.assertEqual('2001:db8::f0:42:8329',
+                         ipv6_utils.get_noscope_ipv6('2001:db8::f0:42:8329%1'))
+        self.assertEqual('ff02::5678',
+                         ipv6_utils.get_noscope_ipv6('ff02::5678%eth0'))
+        self.assertEqual('fe80::1',
+                         ipv6_utils.get_noscope_ipv6('fe80::1%eth0'))
+        self.assertEqual('::1', ipv6_utils.get_noscope_ipv6('::1%eth0'))
+        self.assertEqual('::1', ipv6_utils.get_noscope_ipv6('::1'))
+        self.assertRaises(ValueError, ipv6_utils.get_noscope_ipv6, '::132:::')