Fix IPv6 netmask format for sysconfig (#1215)

This change converts the IPv6 netmask from the network_data.json[1]
format to the CIDR style, <IPv6_addr>/<prefix>.

Using an IPv6 address like ffff:ffff:ffff:ffff:: does not work with
NetworkManager, nor networkscripts.

NetworkManager will ignore the route, logging:
  ifcfg-rh: ignoring invalid route at \
    "::/:: via fd00:fd00:fd00:2::fffe dev $DEV" \
    (/etc/sysconfig/network-scripts/route6-$DEV:3): \
    Argument for "::/::" is not ADDR/PREFIX format

Similarly if using networkscripts, ip route fail with error:
  Error: inet6 prefix is expected rather than \
    "fd00:fd00:fd00::/ffff:ffff:ffff:ffff::".

Also a bit of refactoring ...

cloudinit.net.sysconfig.Route.to_string:
* Move a couple of lines around to reduce repeated code.
* if "ADDRESS" not in key -> continute, so that the
  code block following it can be de-indented.
cloudinit.net.network_state:
* Refactors the ipv4_mask_to_net_prefix, ipv6_mask_to_net_prefix
  removes mask_to_net_prefix methods. Utilize ipaddress library to
  do some of the heavy lifting.

LP: #1959148

1 files changed, 57 insertions, 1 deletions

diff --git a/tests/unittests/net/test_network_state.py b/tests/unittests/net/test_network_state.py
index 88da9f94..471d969a 100644
--- a/tests/unittests/net/test_network_state.py
+++ b/tests/unittests/net/test_network_state.py
@@ -1,5 +1,5 @@
 # This file is part of cloud-init. See LICENSE file for license information.
-
+import ipaddress
 from unittest import mock
 
 import pytest
@@ -163,4 +163,60 @@ class TestNetworkStateParseNameservers:
         ] == sorted(config.dns_searchdomains)
 
 
+class TestNetworkStateHelperFunctions(CiTestCase):
+    def test_mask_to_net_prefix_ipv4(self):
+        netmask_value = "255.255.255.0"
+        expected = 24
+        prefix_value = network_state.ipv4_mask_to_net_prefix(netmask_value)
+        assert prefix_value == expected
+
+    def test_mask_to_net_prefix_all_bits_ipv4(self):
+        netmask_value = "255.255.255.255"
+        expected = 32
+        prefix_value = network_state.ipv4_mask_to_net_prefix(netmask_value)
+        assert prefix_value == expected
+
+    def test_mask_to_net_prefix_to_many_bits_ipv4(self):
+        netmask_value = "33"
+        self.assertRaises(
+            ValueError, network_state.ipv4_mask_to_net_prefix, netmask_value
+        )
+
+    def test_mask_to_net_prefix_all_bits_ipv6(self):
+        netmask_value = "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff"
+        expected = 128
+        prefix_value = network_state.ipv6_mask_to_net_prefix(netmask_value)
+        assert prefix_value == expected
+
+    def test_mask_to_net_prefix_ipv6(self):
+        netmask_value = "ffff:ffff:ffff:ffff::"
+        expected = 64
+        prefix_value = network_state.ipv6_mask_to_net_prefix(netmask_value)
+        assert prefix_value == expected
+
+    def test_mask_to_net_prefix_raises_value_error(self):
+        netmask_value = "ff:ff:ff:ff::"
+        self.assertRaises(
+            ValueError, network_state.ipv6_mask_to_net_prefix, netmask_value
+        )
+
+    def test_mask_to_net_prefix_to_many_bits_ipv6(self):
+        netmask_value = "129"
+        self.assertRaises(
+            ValueError, network_state.ipv6_mask_to_net_prefix, netmask_value
+        )
+
+    def test_mask_to_net_prefix_ipv4_object(self):
+        netmask_value = ipaddress.IPv4Address("255.255.255.255")
+        expected = 32
+        prefix_value = network_state.ipv4_mask_to_net_prefix(netmask_value)
+        assert prefix_value == expected
+
+    def test_mask_to_net_prefix_ipv6_object(self):
+        netmask_value = ipaddress.IPv6Address("ffff:ffff:ffff::")
+        expected = 48
+        prefix_value = network_state.ipv6_mask_to_net_prefix(netmask_value)
+        assert prefix_value == expected
+
+
 # vi: ts=4 expandtab