net_util: ensure static configs have netmask in translate_network result

If a DataSource provides a network configuration in version 2 and runs
on a distro which does not have a network renderer class in use, then
the conversion of V2 to eni results in static ip configurations with
subnet prefix-length (192.168.23.1/24) rather than explicit netmask
value.

When sending such a config to net_util.translate_network the resulting
dictionary is missing the 'netmask' key for static configured addresses
breaking network configurations on multiple distributions.

This patch detects static ip configurations using prefix-length and
converts the format into the previous 'address' and 'netmask' parts
to keep compatibility for these distribtuions until they move to
the v2 network configuration.

LP: #1792454

2 files changed, 58 insertions, 0 deletions

diff --git a/cloudinit/distros/net_util.py b/cloudinit/distros/net_util.py
index 1ce1aa71..edfcd99d 100644
--- a/cloudinit/distros/net_util.py
+++ b/cloudinit/distros/net_util.py
@@ -67,6 +67,10 @@
 #     }
 # }
 
+from cloudinit.net.network_state import (
+    net_prefix_to_ipv4_mask, mask_and_ipv4_to_bcast_addr)
+
+
 def translate_network(settings):
     # Get the standard cmd, args from the ubuntu format
     entries = []
@@ -134,6 +138,21 @@ def translate_network(settings):
                     val = info[k].strip().lower()
                     if val:
                         iface_info[k] = val
+            # handle static ip configurations using
+            # ipaddress/prefix-length format
+            if 'address' in iface_info:
+                if 'netmask' not in iface_info:
+                    # check if the address has a network prefix
+                    addr, _, prefix = iface_info['address'].partition('/')
+                    if prefix:
+                        iface_info['netmask'] = (
+                            net_prefix_to_ipv4_mask(prefix))
+                        iface_info['address'] = addr
+                        # if we set the netmask, we also can set the broadcast
+                        iface_info['broadcast'] = (
+                            mask_and_ipv4_to_bcast_addr(
+                                iface_info['netmask'], addr))
+
             # Name server info provided??
             if 'dns-nameservers' in info:
                 iface_info['dns-nameservers'] = info['dns-nameservers'].split()
diff --git a/tests/unittests/test_distros/test_netconfig.py b/tests/unittests/test_distros/test_netconfig.py
index 740fb76c..9bbff451 100644
--- a/tests/unittests/test_distros/test_netconfig.py
+++ b/tests/unittests/test_distros/test_netconfig.py
@@ -34,6 +34,19 @@ auto eth1
 iface eth1 inet dhcp
 '''
 
+BASE_NET_CFG_FROM_V2 = '''
+auto lo
+iface lo inet loopback
+
+auto eth0
+iface eth0 inet static
+    address 192.168.1.5/24
+    gateway 192.168.1.254
+
+auto eth1
+iface eth1 inet dhcp
+'''
+
 BASE_NET_CFG_IPV6 = '''
 auto lo
 iface lo inet loopback
@@ -262,6 +275,32 @@ hn0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
                 '''), results[rc_conf])
         self.assertEqual(0o644, get_mode(rc_conf, tmpd))
 
+    def test_simple_write_freebsd_from_v2eni(self):
+        fbsd_distro = self._get_distro('freebsd')
+
+        rc_conf = '/etc/rc.conf'
+        read_bufs = {
+            rc_conf: 'initial-rc-conf-not-validated',
+            '/etc/resolv.conf': 'initial-resolv-conf-not-validated',
+        }
+
+        tmpd = self.tmp_dir()
+        populate_dir(tmpd, read_bufs)
+        with self.reRooted(tmpd):
+            with mock.patch("cloudinit.distros.freebsd.util.subp",
+                            return_value=('vtnet0', '')):
+                fbsd_distro.apply_network(BASE_NET_CFG_FROM_V2, False)
+                results = dir2dict(tmpd)
+
+        self.assertIn(rc_conf, results)
+        self.assertCfgEquals(
+            dedent('''\
+                ifconfig_vtnet0="192.168.1.5 netmask 255.255.255.0"
+                ifconfig_vtnet1="DHCP"
+                defaultrouter="192.168.1.254"
+                '''), results[rc_conf])
+        self.assertEqual(0o644, get_mode(rc_conf, tmpd))
+
     def test_apply_network_config_fallback_freebsd(self):
         fbsd_distro = self._get_distro('freebsd')