T7950: VPP: Unexpected None interface in CGNAT when ethernet subinterface is removed from vif

Do not allow to delete subinterface if it is in use in VPP NAT features

Author: natali-rs1985

src/conf_mode/interfaces_ethernet.py

@@ -171,6 +171,13 @@ def get_config(config=None):
 
     ethernet['flowtable_interfaces'] = get_flowtable_interfaces(conf)
 
+    ethernet['vpp'] = conf.get_config_dict(
+        ['vpp'],
+        key_mangling=('-', '_'),
+        get_first_key=True,
+        no_tag_node_value_mangle=True,
+    )
+
     return ethernet
 
 def verify_speed_duplex(ethernet: dict, ethtool: Ethtool):
@@ -301,8 +308,26 @@ def verify_flowtable(ethernet: dict):
                     if vifcname in ethernet['flowtable_interfaces']:
                         raise ConfigError(f'Cannot delete interface "{vifcname}", still referenced on a flowtable')
 
+def verify_vpp_remove_vif(ethernet: dict):
+    """Ensure that VIF interfaces being removed are not used by VPP NAT features"""
+    ifname = ethernet['ifname']
+
+    for vif_type in ['vif_remove', 'vif_s_remove']:
+        for vif in ethernet.get(vif_type, []):
+            vif_name = f'{ifname}.{vif}'
+
+            for path in ['vpp.nat44', 'vpp.nat.cgnat']:
+                for direction in ['inside', 'outside']:
+                    interfaces = dict_search(f'{path}.interface.{direction}', ethernet)
+                    if interfaces and vif_name in interfaces:
+                        raise ConfigError(
+                            f'Cannot delete interface "{vif_name}", it is still in use by '
+                            f'"{path.replace(".", " ")}" as {direction} interface'
+                        )
+
 def verify(ethernet):
     verify_flowtable(ethernet)
+    verify_vpp_remove_vif(ethernet)
 
     if 'deleted' in ethernet:
         return None