host_labels_interfaces: fix subnet identification

.. by using collapse_addresses() instead of comparing `.network` attributes

CMK-31375

Change-Id: Ib390795450fc23ee036e48f023e7efb506908efc

Author: Frans Fürst

packages/cmk-plugins/cmk/plugins/lib/host_labels_interfaces.py

@@ -5,7 +5,9 @@
 
 from collections.abc import Iterable, Mapping
 from ipaddress import (
+    collapse_addresses,
     IPv4Interface,
+    IPv4Network,
     IPv6Interface,
     IPv6Network,
 )
@@ -36,31 +38,41 @@ def host_labels_if(
     """Return host labels describing the host's network 'single-/multihomed' property based on
     the IP addresses of its interfaces.
     Filters away temporary interfaces and local IP addresses (based on interface name and IP's
-    ULA prefix, link-local/unspecified/local-host properties) and checks if the remaining IPs
-    belong to one or more subnets.
+    ULA prefix, link-local/unspecified/local-host properties) and counts non-overlapping
+    networks of the remaining addresses.
     """
     # Original author: thl-cmk[at]outlook[dot]com
 
     for version in (4, 6):
-        if valid_networks := set(
-            # note: contains subnet mask, e.g. 1.2.3.4/24 != 1.2.3.4/32
-            #       for now we define this to be different in terms of single-/multihomed
-            #       for sake of simplicity, but we might want to change this in the future
-            str(interface_ip.network)
+        valid_networks = [
+            interface_ip.network
             for name, interface_ips in interfaces.items()
             if not any(name.startswith(prefix) for prefix in TEMP_DEVICES)
             for interface_ip in interface_ips
-            if interface_ip.version == version
-            and not any(
+            if not any(
                 (
                     interface_ip.is_loopback,
                     interface_ip.is_link_local,
                     interface_ip.is_unspecified,
                     interface_ip in IPV6_ULA_NETWORK,
                 )
             )
+        ]
+
+        if (
+            network_count := len(
+                list(
+                    collapse_addresses([ip for ip in valid_networks if isinstance(ip, IPv4Network)])
+                )
+            )
+            if version == 4
+            else len(
+                list(
+                    collapse_addresses([ip for ip in valid_networks if isinstance(ip, IPv6Network)])
+                )
+            )
         ):
             yield HostLabel(
                 name=f"cmk/l3v{version}_topology",
-                value="singlehomed" if len(valid_networks) == 1 else "multihomed",
+                value="singlehomed" if network_count == 1 else "multihomed",
             )

packages/cmk-plugins/tests/cmk/plugins/lib/test_host_labels_interfaces.py

@@ -28,12 +28,12 @@
         pytest.param(
             {
                 "eth0": [
-                    IPv4Interface("10.86.60.1/27"),
+                    IPv4Interface("10.86.60.1/24"),
                     IPv6Interface("fe80::200:5efe:515c:6232/64"),
                 ],
                 "eth1": [
                     IPv6Interface("fe80::200:5efe:515c:6232/64"),
-                    IPv4Interface("12.12.12.1/3"),
+                    IPv4Interface("12.12.12.1/24"),
                 ],
             },
             [
@@ -65,12 +65,12 @@
                 ],
                 "enp0s31f6": [
                     IPv4Interface("95.216.118.249"),
-                    IPv6Interface("2a01:4f9:2b:1c86::2/128"),  # note: different subnet than..
+                    IPv6Interface("2a01:4f9:2b:1c86::2/128"),
                     IPv6Interface("fe80::921b:eff:fefe:8a16/64"),
                 ],
                 "vmbr0": [
                     IPv4Interface("95.217.149.46/32"),
-                    IPv6Interface("2a01:4f9:2b:1c86::2/64"),  #  .. this one -> multihomed for now
+                    IPv6Interface("2a01:4f9:2b:1c86::2/64"),
                     IPv6Interface("fe80::6871:a0ff:fefe:cd60/64"),
                 ],
                 "vmbr1": [
@@ -81,7 +81,7 @@
             },
             [
                 HostLabel("cmk/l3v4_topology", "multihomed"),
-                HostLabel("cmk/l3v6_topology", "multihomed"),
+                HostLabel("cmk/l3v6_topology", "singlehomed"),
             ],
             id="host_labels_03",
         ),

tests/unit/cmk/plugins/network/agent_based/test_ip_addresses.py

@@ -198,9 +198,9 @@ def test_parse_ip_addresses(
         (None, []),
         (
             (
-                {"16": IPv4Interface("10.86.60.1/27")},
+                {"16": IPv4Interface("10.86.60.1/24")},
                 {"20": IPv6Interface("fe80::200:5efe:515c:6232/64")},
-                {"if_index1": IPv4Interface("12.12.12.1/3")},
+                {"if_index1": IPv4Interface("12.12.12.1/24")},
             ),
             [
                 HostLabel("cmk/l3v4_topology", "multihomed"),