Fixes #2514: Prevent new connections to already connected interfaces

CHANGELOG.md

@@ -2,6 +2,7 @@ v2.4.7 (FUTURE)
 
 ## Bug Fixes
 
+* [#2514](https://github.com/digitalocean/netbox/issues/2514) - Prevent new connections to already connected interfaces
 * [#2515](https://github.com/digitalocean/netbox/issues/2515) - Only use django-rq admin tmeplate if webhooks are enabled
 
 ---

netbox/dcim/api/serializers.py

@@ -472,10 +472,14 @@ class ConsoleServerPortSerializer(TaggitSerializer, ValidatedModelSerializer):
 class NestedConsoleServerPortSerializer(WritableNestedSerializer):
     url = serializers.HyperlinkedIdentityField(view_name='dcim-api:consoleserverport-detail')
     device = NestedDeviceSerializer(read_only=True)
+    is_connected = serializers.SerializerMethodField(read_only=True)
 
     class Meta:
         model = ConsoleServerPort
-        fields = ['id', 'url', 'device', 'name']
+        fields = ['id', 'url', 'device', 'name', 'is_connected']
+
+    def get_is_connected(self, obj):
+        return hasattr(obj, 'connected_console') and obj.connected_console is not None
 
 
 #
@@ -495,10 +499,14 @@ class ConsolePortSerializer(TaggitSerializer, ValidatedModelSerializer):
 class NestedConsolePortSerializer(TaggitSerializer, ValidatedModelSerializer):
     url = serializers.HyperlinkedIdentityField(view_name='dcim-api:consoleport-detail')
     device = NestedDeviceSerializer(read_only=True)
+    is_connected = serializers.SerializerMethodField(read_only=True)
 
     class Meta:
         model = ConsolePort
-        fields = ['id', 'url', 'device', 'name']
+        fields = ['id', 'url', 'device', 'name', 'is_connected']
+
+    def get_is_connected(self, obj):
+        return obj.cs_port is not None
 
 
 #
@@ -518,10 +526,14 @@ class PowerOutletSerializer(TaggitSerializer, ValidatedModelSerializer):
 class NestedPowerOutletSerializer(WritableNestedSerializer):
     url = serializers.HyperlinkedIdentityField(view_name='dcim-api:poweroutlet-detail')
     device = NestedDeviceSerializer(read_only=True)
+    is_connected = serializers.SerializerMethodField(read_only=True)
 
     class Meta:
         model = PowerOutlet
-        fields = ['id', 'url', 'device', 'name']
+        fields = ['id', 'url', 'device', 'name', 'is_connected']
+
+    def get_is_connected(self, obj):
+        return hasattr(obj, 'connected_port') and obj.connected_port is not None
 
 
 #
@@ -541,23 +553,43 @@ class PowerPortSerializer(TaggitSerializer, ValidatedModelSerializer):
 class NestedPowerPortSerializer(TaggitSerializer, ValidatedModelSerializer):
     url = serializers.HyperlinkedIdentityField(view_name='dcim-api:powerport-detail')
     device = NestedDeviceSerializer(read_only=True)
+    is_connected = serializers.SerializerMethodField(read_only=True)
 
     class Meta:
         model = PowerPort
-        fields = ['id', 'url', 'device', 'name']
+        fields = ['id', 'url', 'device', 'name', 'is_connected']
+
+    def get_is_connected(self, obj):
+        return obj.power_outlet is not None
 
 
 #
 # Interfaces
 #
 
-class NestedInterfaceSerializer(WritableNestedSerializer):
+class IsConnectedMixin(object):
+    """
+    Provide a method for setting is_connected on Interface serializers.
+    """
+    def get_is_connected(self, obj):
+        """
+        Return True if the interface has a connected interface or circuit.
+        """
+        if obj.connection:
+            return True
+        if hasattr(obj, 'circuit_termination') and obj.circuit_termination is not None:
+            return True
+        return False
+
+
+class NestedInterfaceSerializer(IsConnectedMixin, WritableNestedSerializer):
     device = NestedDeviceSerializer(read_only=True)
     url = serializers.HyperlinkedIdentityField(view_name='dcim-api:interface-detail')
+    is_connected = serializers.SerializerMethodField(read_only=True)
 
     class Meta:
         model = Interface
-        fields = ['id', 'url', 'device', 'name']
+        fields = ['id', 'url', 'device', 'name', 'is_connected']
 
 
 class InterfaceNestedCircuitSerializer(serializers.ModelSerializer):
@@ -587,7 +619,7 @@ class InterfaceVLANSerializer(WritableNestedSerializer):
         fields = ['id', 'url', 'vid', 'name', 'display_name']
 
 
-class InterfaceSerializer(TaggitSerializer, ValidatedModelSerializer):
+class InterfaceSerializer(TaggitSerializer, IsConnectedMixin, ValidatedModelSerializer):
     device = NestedDeviceSerializer()
     form_factor = ChoiceField(choices=IFACE_FF_CHOICES, required=False)
     lag = NestedInterfaceSerializer(required=False, allow_null=True)
@@ -631,19 +663,6 @@ class InterfaceSerializer(TaggitSerializer, ValidatedModelSerializer):
 
         return super(InterfaceSerializer, self).validate(data)
 
-    def get_is_connected(self, obj):
-        """
-        Return True if the interface has a connected interface or circuit termination.
-        """
-        if obj.connection:
-            return True
-        try:
-            circuit_termination = obj.circuit_termination
-            return True
-        except CircuitTermination.DoesNotExist:
-            pass
-        return False
-
     def get_interface_connection(self, obj):
         if obj.connection:
             context = {

netbox/dcim/forms.py

@@ -1328,7 +1328,7 @@ class ConsolePortConnectionForm(BootstrapMixin, ChainedFieldsMixin, forms.ModelF
         label='Port',
         widget=APISelect(
             api_url='/api/dcim/console-server-ports/?device_id={{console_server}}',
-            disabled_indicator='connected_console',
+            disabled_indicator='is_connected',
         )
     )
 
@@ -1419,7 +1419,7 @@ class ConsoleServerPortConnectionForm(BootstrapMixin, ChainedFieldsMixin, forms.
         label='Port',
         widget=APISelect(
             api_url='/api/dcim/console-ports/?device_id={{device}}',
-            disabled_indicator='cs_port'
+            disabled_indicator='is_connected'
         )
     )
     connection_status = forms.BooleanField(
@@ -1597,7 +1597,7 @@ class PowerPortConnectionForm(BootstrapMixin, ChainedFieldsMixin, forms.ModelFor
         label='Outlet',
         widget=APISelect(
             api_url='/api/dcim/power-outlets/?device_id={{pdu}}',
-            disabled_indicator='connected_port'
+            disabled_indicator='is_connected'
         )
     )
 
@@ -1688,7 +1688,7 @@ class PowerOutletConnectionForm(BootstrapMixin, ChainedFieldsMixin, forms.Form):
         label='Port',
         widget=APISelect(
             api_url='/api/dcim/power-ports/?device_id={{device}}',
-            disabled_indicator='power_outlet'
+            disabled_indicator='is_connected'
         )
     )
     connection_status = forms.BooleanField(

netbox/dcim/models.py

@@ -2035,25 +2035,44 @@ class InterfaceConnection(models.Model):
     csv_headers = ['device_a', 'interface_a', 'device_b', 'interface_b', 'connection_status']
 
     def clean(self):
-        try:
-            if self.interface_a == self.interface_b:
-                raise ValidationError({
-                    'interface_b': "Cannot connect an interface to itself."
-                })
-            if self.interface_a.form_factor in NONCONNECTABLE_IFACE_TYPES:
-                raise ValidationError({
-                    'interface_a': '{} is not a connectable interface type.'.format(
-                        self.interface_a.get_form_factor_display()
-                    )
-                })
-            if self.interface_b.form_factor in NONCONNECTABLE_IFACE_TYPES:
-                raise ValidationError({
-                    'interface_b': '{} is not a connectable interface type.'.format(
-                        self.interface_b.get_form_factor_display()
-                    )
-                })
-        except ObjectDoesNotExist:
-            pass
+
+        # An interface cannot be connected to itself
+        if self.interface_a == self.interface_b:
+            raise ValidationError({
+                'interface_b': "Cannot connect an interface to itself."
+            })
+
+        # Only connectable interface types are permitted
+        if self.interface_a.form_factor in NONCONNECTABLE_IFACE_TYPES:
+            raise ValidationError({
+                'interface_a': '{} is not a connectable interface type.'.format(
+                    self.interface_a.get_form_factor_display()
+                )
+            })
+        if self.interface_b.form_factor in NONCONNECTABLE_IFACE_TYPES:
+            raise ValidationError({
+                'interface_b': '{} is not a connectable interface type.'.format(
+                    self.interface_b.get_form_factor_display()
+                )
+            })
+
+        # Prevent the A side of one connection from being the B side of another
+        interface_a_connections = InterfaceConnection.objects.filter(
+            Q(interface_a=self.interface_a) |
+            Q(interface_b=self.interface_a)
+        ).exclude(pk=self.pk)
+        if interface_a_connections.exists():
+            raise ValidationError({
+                'interface_a': "This interface is already connected."
+            })
+        interface_b_connections = InterfaceConnection.objects.filter(
+            Q(interface_a=self.interface_b) |
+            Q(interface_b=self.interface_b)
+        ).exclude(pk=self.pk)
+        if interface_b_connections.exists():
+            raise ValidationError({
+                'interface_b': "This interface is already connected."
+            })
 
     def to_csv(self):
         return (

netbox/dcim/tests/test_api.py

@@ -1955,7 +1955,7 @@ class ConsolePortTest(APITestCase):
 
         self.assertEqual(
             sorted(response.data['results'][0]),
-            ['device', 'id', 'name', 'url']
+            ['device', 'id', 'is_connected', 'name', 'url']
         )
 
     def test_create_consoleport(self):
@@ -2070,7 +2070,7 @@ class ConsoleServerPortTest(APITestCase):
 
         self.assertEqual(
             sorted(response.data['results'][0]),
-            ['device', 'id', 'name', 'url']
+            ['device', 'id', 'is_connected', 'name', 'url']
         )
 
     def test_create_consoleserverport(self):
@@ -2181,7 +2181,7 @@ class PowerPortTest(APITestCase):
 
         self.assertEqual(
             sorted(response.data['results'][0]),
-            ['device', 'id', 'name', 'url']
+            ['device', 'id', 'is_connected', 'name', 'url']
         )
 
     def test_create_powerport(self):
@@ -2296,7 +2296,7 @@ class PowerOutletTest(APITestCase):
 
         self.assertEqual(
             sorted(response.data['results'][0]),
-            ['device', 'id', 'name', 'url']
+            ['device', 'id', 'is_connected', 'name', 'url']
         )
 
     def test_create_poweroutlet(self):
@@ -2432,7 +2432,7 @@ class InterfaceTest(APITestCase):
 
         self.assertEqual(
             sorted(response.data['results'][0]),
-            ['device', 'id', 'name', 'url']
+            ['device', 'id', 'is_connected', 'name', 'url']
         )
 
     def test_create_interface(self):