netbox/netbox/dcim/models/device_components.py

from functools import cached_property

from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
from django.contrib.postgres.fields import ArrayField
from django.core.exceptions import ObjectDoesNotExist, ValidationError
from django.core.validators import MaxValueValidator, MinValueValidator
from django.db import models
from django.db.models import Sum
from django.utils.translation import gettext_lazy as _
from mptt.models import MPTTModel, TreeForeignKey

from dcim.choices import *
from dcim.constants import *
from dcim.fields import WWNField
from dcim.models.base import PortMappingBase
from dcim.models.mixins import InterfaceValidationMixin
from netbox.choices import ColorChoices
from netbox.models import NetBoxModel, OrganizationalModel
from netbox.models.mixins import OwnerMixin
from utilities.fields import ColorField, NaturalOrderingField
from utilities.mptt import TreeManager
from utilities.ordering import naturalize_interface
from utilities.query_functions import CollateAsChar
from utilities.tracking import TrackingModelMixin
from wireless.choices import *
from wireless.utils import get_channel_attr

__all__ = (
    'BaseInterface',
    'CabledObjectModel',
    'ConsolePort',
    'ConsoleServerPort',
    'DeviceBay',
    'FrontPort',
    'Interface',
    'InventoryItem',
    'InventoryItemRole',
    'ModuleBay',
    'PathEndpoint',
    'PortMapping',
    'PowerOutlet',
    'PowerPort',
    'RearPort',
)


class ComponentModel(OwnerMixin, NetBoxModel):
    """
    An abstract model inherited by any model which has a parent Device.
    """
    device = models.ForeignKey(
        to='dcim.Device',
        on_delete=models.CASCADE,
        related_name='%(class)ss'
    )
    name = models.CharField(
        verbose_name=_('name'),
        max_length=64,
        db_collation="natural_sort"
    )
    label = models.CharField(
        verbose_name=_('label'),
        max_length=64,
        blank=True,
        help_text=_('Physical label')
    )
    description = models.CharField(
        verbose_name=_('description'),
        max_length=200,
        blank=True
    )

    # Denormalized references replicated from the parent Device
    _site = models.ForeignKey(
        to='dcim.Site',
        on_delete=models.SET_NULL,
        related_name='+',
        blank=True,
        null=True,
    )
    _location = models.ForeignKey(
        to='dcim.Location',
        on_delete=models.SET_NULL,
        related_name='+',
        blank=True,
        null=True,
    )
    _rack = models.ForeignKey(
        to='dcim.Rack',
        on_delete=models.SET_NULL,
        related_name='+',
        blank=True,
        null=True,
    )

    class Meta:
        abstract = True
        ordering = ('device', 'name')
        constraints = (
            models.UniqueConstraint(
                fields=('device', 'name'),
                name='%(app_label)s_%(class)s_unique_device_name'
            ),
        )

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        # Cache the original Device ID for reference under clean()
        self._original_device = self.__dict__.get('device_id')

    def __str__(self):
        if self.label:
            return f"{self.name} ({self.label})"
        return self.name

    def to_objectchange(self, action):
        objectchange = super().to_objectchange(action)
        objectchange.related_object = self.device
        return objectchange

    def clean(self):
        super().clean()

        # Check list of Modules that allow device field to be changed
        if (type(self) not in [InventoryItem]) and (self.pk is not None) and (self._original_device != self.device_id):
            raise ValidationError({
                "device": _("Components cannot be moved to a different device.")
            })

    def save(self, *args, **kwargs):
        # Save denormalized references
        self._site = self.device.site
        self._location = self.device.location
        self._rack = self.device.rack

        super().save(*args, **kwargs)

    @property
    def parent_object(self):
        return self.device


class ModularComponentModel(ComponentModel):
    module = models.ForeignKey(
        to='dcim.Module',
        on_delete=models.CASCADE,
        related_name='%(class)ss',
        blank=True,
        null=True
    )
    inventory_items = GenericRelation(
        to='dcim.InventoryItem',
        content_type_field='component_type',
        object_id_field='component_id'
    )

    class Meta(ComponentModel.Meta):
        abstract = True


class CabledObjectModel(models.Model):
    """
    An abstract model inherited by all models to which a Cable can terminate. Provides the `cable` and `cable_end`
    fields for caching cable associations, as well as `mark_connected` to designate "fake" connections.
    """
    cable = models.ForeignKey(
        to='dcim.Cable',
        on_delete=models.SET_NULL,
        related_name='+',
        blank=True,
        null=True
    )
    cable_end = models.CharField(
        verbose_name=_('cable end'),
        max_length=1,
        choices=CableEndChoices,
        blank=True,
        null=True
    )
    cable_connector = models.PositiveSmallIntegerField(
        blank=True,
        null=True,
        validators=(
            MinValueValidator(CABLE_CONNECTOR_MIN),
            MaxValueValidator(CABLE_CONNECTOR_MAX)
        ),
    )
    cable_positions = ArrayField(
        base_field=models.PositiveSmallIntegerField(
            validators=(
                MinValueValidator(CABLE_POSITION_MIN),
                MaxValueValidator(CABLE_POSITION_MAX)
            )
        ),
        blank=True,
        null=True,
    )
    mark_connected = models.BooleanField(
        verbose_name=_('mark connected'),
        default=False,
        help_text=_('Treat as if a cable is connected')
    )

    cable_terminations = GenericRelation(
        to='dcim.CableTermination',
        content_type_field='termination_type',
        object_id_field='termination_id',
        related_query_name='%(class)s',
    )

    class Meta:
        abstract = True

    def clean(self):
        super().clean()

        if self.cable:
            if not self.cable_end:
                raise ValidationError({
                    "cable_end": _("Must specify cable end (A or B) when attaching a cable.")
                })
            if self.cable_connector and not self.cable_positions:
                raise ValidationError({
                    "cable_positions": _("Must specify position(s) when specifying a cable connector.")
                })
            if self.cable_positions and not self.cable_connector:
                raise ValidationError({
                    "cable_positions": _("Cable positions cannot be set without a cable connector.")
                })
            if self.mark_connected:
                raise ValidationError({
                    "mark_connected": _("Cannot mark as connected with a cable attached.")
                })
        else:
            if self.cable_end:
                raise ValidationError({
                    "cable_end": _("Cable end must not be set without a cable.")
                })
            if self.cable_connector:
                raise ValidationError({
                    "cable_connector": _("Cable connector must not be set without a cable.")
                })
            if self.cable_positions:
                raise ValidationError({
                    "cable_positions": _("Cable termination positions must not be set without a cable.")
                })

    @property
    def link(self):
        """
        Generic wrapper for a Cable, WirelessLink, or some other relation to a connected termination.
        """
        return self.cable

    @cached_property
    def link_peers(self):
        if self.cable:
            return [
                peer.termination
                for peer in self.cable.terminations.all()
                if peer.cable_end != self.cable_end
            ]
        return []

    @property
    def _occupied(self):
        return bool(self.mark_connected or self.cable_id)

    @property
    def parent_object(self):
        raise NotImplementedError(
            _("{class_name} models must declare a parent_object property").format(class_name=self.__class__.__name__)
        )

    @property
    def opposite_cable_end(self):
        if not self.cable_end:
            return None
        return CableEndChoices.SIDE_A if self.cable_end == CableEndChoices.SIDE_B else CableEndChoices.SIDE_B

    def set_cable_termination(self, termination):
        """Save attributes from the given CableTermination on the terminating object."""
        self.cable = termination.cable
        self.cable_end = termination.cable_end
        self.cable_connector = termination.connector
        self.cable_positions = termination.positions
    set_cable_termination.alters_data = True

    def clear_cable_termination(self, termination):
        """Clear all cable termination attributes from the terminating object."""
        self.cable = None
        self.cable_end = None
        self.cable_connector = None
        self.cable_positions = None
    clear_cable_termination.alters_data = True


class PathEndpoint(models.Model):
    """
    An abstract model inherited by any CabledObjectModel subclass which represents the end of a CablePath; specifically,
    these include ConsolePort, ConsoleServerPort, PowerPort, PowerOutlet, Interface, and PowerFeed.

    `_path` references the CablePath originating from this instance, if any. It is set or cleared by the receivers in
    dcim.signals in response to changes in the cable path, and complements the `origin` GenericForeignKey field on the
    CablePath model. `_path` should not be accessed directly; rather, use the `path` property.

    `connected_endpoints()` is a convenience method for returning the destination of the associated CablePath, if any.
    """

    _path = models.ForeignKey(
        to='dcim.CablePath',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
    )

    class Meta:
        abstract = True

    def trace(self):
        origin = self
        path = []

        # Construct the complete path (including e.g. bridged interfaces)
        while origin is not None:
            # Go through the public accessor rather than dereferencing `_path`
            # directly. During cable edits, CablePath rows can be deleted and
            # recreated while this endpoint instance is still in memory.
            cable_path = origin.path
            if cable_path is None:
                break

            path.extend(cable_path.path_objects)

            # If the path ends at a non-connected pass-through port, pad out the link and far-end terminations
            if len(path) % 3 == 1:
                path.extend(([], []))
            # If the path ends at a site or provider network, inject a null "link" to render an attachment
            elif len(path) % 3 == 2:
                path.insert(-1, [])

            # Check for a bridged relationship to continue the trace.
            destinations = cable_path.destinations
            if len(destinations) == 1:
                origin = getattr(destinations[0], 'bridge', None)
            else:
                origin = None

        # Return the path as a list of three-tuples (A termination(s), cable(s), B termination(s))
        return list(zip(*[iter(path)] * 3))

    @property
    def path(self):
        """
        Return this endpoint's current CablePath, if any.

        `_path` is a denormalized reference that is updated from CablePath
        save/delete handlers, including queryset.update() calls on origin
        endpoints. That means an already-instantiated endpoint can briefly hold
        a stale in-memory `_path` relation while the database already points to
        a different CablePath (or to no path at all).

        If the cached relation points to a CablePath that has just been
        deleted, refresh only the `_path` field from the database and retry.
        This keeps the fix cheap and narrowly scoped to the denormalized FK.
        """
        if self._path_id is None:
            return None

        try:
            return self._path
        except ObjectDoesNotExist:
            # Refresh only the denormalized FK instead of the whole model.
            # The expected problem here is in-memory staleness during path
            # rebuilds, not persistent database corruption.
            self.refresh_from_db(fields=['_path'])
            return self._path if self._path_id else None

    @cached_property
    def connected_endpoints(self):
        """
        Caching accessor for the attached CablePath's destinations (if any).

        Always route through `path` so stale in-memory `_path` references are
        repaired before we cache the result for the lifetime of this instance.
        """
        if cable_path := self.path:
            return cable_path.destinations
        return []


#
# Console components
#

class ConsolePort(ModularComponentModel, CabledObjectModel, PathEndpoint, TrackingModelMixin):
    """
    A physical console port within a Device. ConsolePorts connect to ConsoleServerPorts.
    """
    type = models.CharField(
        verbose_name=_('type'),
        max_length=50,
        choices=ConsolePortTypeChoices,
        blank=True,
        null=True,
        help_text=_('Physical port type')
    )
    speed = models.PositiveIntegerField(
        verbose_name=_('speed'),
        choices=ConsolePortSpeedChoices,
        blank=True,
        null=True,
        help_text=_('Port speed in bits per second')
    )

    clone_fields = ('device', 'module', 'type', 'speed')

    class Meta(ModularComponentModel.Meta):
        verbose_name = _('console port')
        verbose_name_plural = _('console ports')


class ConsoleServerPort(ModularComponentModel, CabledObjectModel, PathEndpoint, TrackingModelMixin):
    """
    A physical port within a Device (typically a designated console server) which provides access to ConsolePorts.
    """
    type = models.CharField(
        verbose_name=_('type'),
        max_length=50,
        choices=ConsolePortTypeChoices,
        blank=True,
        null=True,
        help_text=_('Physical port type')
    )
    speed = models.PositiveIntegerField(
        verbose_name=_('speed'),
        choices=ConsolePortSpeedChoices,
        blank=True,
        null=True,
        help_text=_('Port speed in bits per second')
    )

    clone_fields = ('device', 'module', 'type', 'speed')

    class Meta(ModularComponentModel.Meta):
        verbose_name = _('console server port')
        verbose_name_plural = _('console server ports')


#
# Power components
#

class PowerPort(ModularComponentModel, CabledObjectModel, PathEndpoint, TrackingModelMixin):
    """
    A physical power supply (intake) port within a Device. PowerPorts connect to PowerOutlets.
    """
    type = models.CharField(
        verbose_name=_('type'),
        max_length=50,
        choices=PowerPortTypeChoices,
        blank=True,
        null=True,
        help_text=_('Physical port type')
    )
    maximum_draw = models.PositiveIntegerField(
        verbose_name=_('maximum draw'),
        blank=True,
        null=True,
        validators=[MinValueValidator(1)],
        help_text=_("Maximum power draw (watts)")
    )
    allocated_draw = models.PositiveIntegerField(
        verbose_name=_('allocated draw'),
        blank=True,
        null=True,
        validators=[MinValueValidator(1)],
        help_text=_('Allocated power draw (watts)')
    )

    clone_fields = ('device', 'module', 'maximum_draw', 'allocated_draw')

    class Meta(ModularComponentModel.Meta):
        verbose_name = _('power port')
        verbose_name_plural = _('power ports')

    def clean(self):
        super().clean()

        if self.maximum_draw is not None and self.allocated_draw is not None:
            if self.allocated_draw > self.maximum_draw:
                raise ValidationError({
                    'allocated_draw': _(
                        "Allocated draw cannot exceed the maximum draw ({maximum_draw}W)."
                    ).format(maximum_draw=self.maximum_draw)
                })

    def get_downstream_powerports(self, leg=None):
        """
        Return a queryset of all PowerPorts connected via cable to a child PowerOutlet. For example, in the topology
        below, PP1.get_downstream_powerports() would return PP2-4.

               ---- PO1 <---> PP2
             /
        PP1 ------- PO2 <---> PP3
             \
               ---- PO3 <---> PP4

        """
        poweroutlets = self.poweroutlets.filter(cable__isnull=False)
        if leg:
            poweroutlets = poweroutlets.filter(feed_leg=leg)
        if not poweroutlets:
            return PowerPort.objects.none()

        q = Q()
        for poweroutlet in poweroutlets:
            q |= Q(
                cable=poweroutlet.cable,
                cable_end=poweroutlet.opposite_cable_end
            )

        return PowerPort.objects.filter(q)

    def get_power_draw(self):
        """
        Return the allocated and maximum power draw (in VA) and child PowerOutlet count for this PowerPort.
        """
        from dcim.models import PowerFeed

        # Calculate aggregate draw of all child power outlets if no numbers have been defined manually
        if self.allocated_draw is None and self.maximum_draw is None:
            utilization = self.get_downstream_powerports().aggregate(
                maximum_draw_total=Sum('maximum_draw'),
                allocated_draw_total=Sum('allocated_draw'),
            )
            ret = {
                'allocated': utilization['allocated_draw_total'] or 0,
                'maximum': utilization['maximum_draw_total'] or 0,
                'outlet_count': self.poweroutlets.count(),
                'legs': [],
            }

            # Calculate per-leg aggregates for three-phase power feeds
            if len(self.link_peers) == 1 and isinstance(self.link_peers[0], PowerFeed) and \
                    self.link_peers[0].phase == PowerFeedPhaseChoices.PHASE_3PHASE:
                for leg, leg_name in PowerOutletFeedLegChoices:
                    utilization = self.get_downstream_powerports(leg=leg).aggregate(
                        maximum_draw_total=Sum('maximum_draw'),
                        allocated_draw_total=Sum('allocated_draw'),
                    )
                    ret['legs'].append({
                        'name': leg_name,
                        'allocated': utilization['allocated_draw_total'] or 0,
                        'maximum': utilization['maximum_draw_total'] or 0,
                        'outlet_count': self.poweroutlets.filter(feed_leg=leg).count(),
                    })

            return ret

        # Default to administratively defined values
        return {
            'allocated': self.allocated_draw or 0,
            'maximum': self.maximum_draw or 0,
            'outlet_count': self.poweroutlets.count(),
            'legs': [],
        }


class PowerOutlet(ModularComponentModel, CabledObjectModel, PathEndpoint, TrackingModelMixin):
    """
    A physical power outlet (output) within a Device which provides power to a PowerPort.
    """
    status = models.CharField(
        verbose_name=_('status'),
        max_length=50,
        choices=PowerOutletStatusChoices,
        default=PowerOutletStatusChoices.STATUS_ENABLED
    )
    type = models.CharField(
        verbose_name=_('type'),
        max_length=50,
        choices=PowerOutletTypeChoices,
        blank=True,
        null=True,
        help_text=_('Physical port type')
    )
    power_port = models.ForeignKey(
        to='dcim.PowerPort',
        on_delete=models.SET_NULL,
        blank=True,
        null=True,
        related_name='poweroutlets'
    )
    feed_leg = models.CharField(
        verbose_name=_('feed leg'),
        max_length=50,
        choices=PowerOutletFeedLegChoices,
        blank=True,
        null=True,
        help_text=_('Phase (for three-phase feeds)')
    )
    color = ColorField(
        verbose_name=_('color'),
        blank=True
    )

    clone_fields = ('device', 'module', 'type', 'power_port', 'feed_leg')

    class Meta(ModularComponentModel.Meta):
        verbose_name = _('power outlet')
        verbose_name_plural = _('power outlets')

    def clean(self):
        super().clean()

        # Validate power port assignment
        if self.power_port and self.power_port.device != self.device:
            raise ValidationError(
                _("Parent power port ({power_port}) must belong to the same device").format(power_port=self.power_port)
            )

    def get_status_color(self):
        return PowerOutletStatusChoices.colors.get(self.status)


#
# Interfaces
#

class BaseInterface(models.Model):
    """
    Abstract base class for fields shared by dcim.Interface and virtualization.VMInterface.
    """
    enabled = models.BooleanField(
        verbose_name=_('enabled'),
        default=True
    )
    mtu = models.PositiveIntegerField(
        blank=True,
        null=True,
        validators=[
            MinValueValidator(INTERFACE_MTU_MIN),
            MaxValueValidator(INTERFACE_MTU_MAX)
        ],
        verbose_name=_('MTU')
    )
    mode = models.CharField(
        verbose_name=_('mode'),
        max_length=50,
        choices=InterfaceModeChoices,
        blank=True,
        null=True,
        help_text=_('IEEE 802.1Q tagging strategy')
    )
    parent = models.ForeignKey(
        to='self',
        on_delete=models.RESTRICT,
        related_name='child_interfaces',
        null=True,
        blank=True,
        verbose_name=_('parent interface')
    )
    bridge = models.ForeignKey(
        to='self',
        on_delete=models.SET_NULL,
        related_name='bridge_interfaces',
        null=True,
        blank=True,
        verbose_name=_('bridge interface')
    )
    untagged_vlan = models.ForeignKey(
        to='ipam.VLAN',
        on_delete=models.SET_NULL,
        related_name='%(class)ss_as_untagged',
        null=True,
        blank=True,
        verbose_name=_('untagged VLAN')
    )
    tagged_vlans = models.ManyToManyField(
        to='ipam.VLAN',
        related_name='%(class)ss_as_tagged',
        blank=True,
        verbose_name=_('tagged VLANs')
    )
    qinq_svlan = models.ForeignKey(
        to='ipam.VLAN',
        on_delete=models.SET_NULL,
        related_name='%(class)ss_svlan',
        null=True,
        blank=True,
        verbose_name=_('Q-in-Q SVLAN')
    )
    vlan_translation_policy = models.ForeignKey(
        to='ipam.VLANTranslationPolicy',
        on_delete=models.PROTECT,
        null=True,
        blank=True,
        verbose_name=_('VLAN Translation Policy')
    )
    primary_mac_address = models.OneToOneField(
        to='dcim.MACAddress',
        on_delete=models.SET_NULL,
        related_name='+',
        blank=True,
        null=True,
        verbose_name=_('primary MAC address')
    )

    class Meta:
        abstract = True

    def clean(self):
        super().clean()

        # SVLAN can be defined only for Q-in-Q interfaces
        if self.qinq_svlan and self.mode != InterfaceModeChoices.MODE_Q_IN_Q:
            raise ValidationError({
                'qinq_svlan': _("Only Q-in-Q interfaces may specify a service VLAN.")
            })

        # Check that the primary MAC address (if any) is assigned to this interface
        if (
                self.primary_mac_address and
                self.primary_mac_address.assigned_object is not None and
                self.primary_mac_address.assigned_object != self
        ):
            raise ValidationError({
                'primary_mac_address': _(
                    "MAC address {mac_address} is assigned to a different interface ({interface})."
                ).format(
                    mac_address=self.primary_mac_address,
                    interface=self.primary_mac_address.assigned_object,
                )
            })

    def save(self, *args, **kwargs):

        # Remove untagged VLAN assignment for non-802.1Q interfaces
        if not self.mode:
            self.untagged_vlan = None

        # Only "tagged" interfaces may have tagged VLANs assigned. ("tagged all" implies all VLANs are assigned.)
        if not self._state.adding and self.mode != InterfaceModeChoices.MODE_TAGGED:
            self.tagged_vlans.clear()

        return super().save(*args, **kwargs)

    @property
    def tunnel_termination(self):
        return self.tunnel_terminations.first()

    @property
    def count_ipaddresses(self):
        return self.ip_addresses.count()

    @property
    def count_fhrp_groups(self):
        return self.fhrp_group_assignments.count()

    @cached_property
    def mac_address(self):
        if self.primary_mac_address:
            return self.primary_mac_address.mac_address
        return None


class Interface(
    InterfaceValidationMixin,
    ModularComponentModel,
    BaseInterface,
    CabledObjectModel,
    PathEndpoint,
    TrackingModelMixin,
):
    """
    A network interface within a Device. A physical Interface can connect to exactly one other Interface.
    """
    # Override ComponentModel._name to specify naturalize_interface function
    _name = NaturalOrderingField(
        target_field='name',
        naturalize_function=naturalize_interface,
        max_length=100,
        blank=True
    )
    vdcs = models.ManyToManyField(
        to='dcim.VirtualDeviceContext',
        related_name='interfaces'
    )
    lag = models.ForeignKey(
        to='self',
        on_delete=models.SET_NULL,
        related_name='member_interfaces',
        null=True,
        blank=True,
        verbose_name=_('parent LAG')
    )
    type = models.CharField(
        verbose_name=_('type'),
        max_length=50,
        choices=InterfaceTypeChoices
    )
    mgmt_only = models.BooleanField(
        default=False,
        verbose_name=_('management only'),
        help_text=_('This interface is used only for out-of-band management')
    )
    speed = models.PositiveBigIntegerField(
        blank=True,
        null=True,
        verbose_name=_('speed (Kbps)')
    )
    duplex = models.CharField(
        verbose_name=_('duplex'),
        max_length=50,
        blank=True,
        null=True,
        choices=InterfaceDuplexChoices
    )
    wwn = WWNField(
        null=True,
        blank=True,
        verbose_name=_('WWN'),
        help_text=_('64-bit World Wide Name')
    )
    rf_role = models.CharField(
        max_length=30,
        choices=WirelessRoleChoices,
        blank=True,
        null=True,
        verbose_name=_('wireless role')
    )
    rf_channel = models.CharField(
        max_length=50,
        choices=WirelessChannelChoices,
        blank=True,
        null=True,
        verbose_name=_('wireless channel')
    )
    rf_channel_frequency = models.DecimalField(
        max_digits=8,
        decimal_places=3,
        blank=True,
        null=True,
        verbose_name=_('channel frequency (MHz)'),
        help_text=_("Populated by selected channel (if set)")
    )
    rf_channel_width = models.DecimalField(
        max_digits=7,
        decimal_places=3,
        blank=True,
        null=True,
        verbose_name=('channel width (MHz)'),
        help_text=_("Populated by selected channel (if set)")
    )
    tx_power = models.SmallIntegerField(
        blank=True,
        null=True,
        validators=(
            MinValueValidator(-40),
            MaxValueValidator(127),
        ),
        verbose_name=_('transmit power (dBm)')
    )
    poe_mode = models.CharField(
        max_length=50,
        choices=InterfacePoEModeChoices,
        blank=True,
        null=True,
        verbose_name=_('PoE mode')
    )
    poe_type = models.CharField(
        max_length=50,
        choices=InterfacePoETypeChoices,
        blank=True,
        null=True,
        verbose_name=_('PoE type')
    )
    wireless_link = models.ForeignKey(
        to='wireless.WirelessLink',
        on_delete=models.SET_NULL,
        related_name='+',
        blank=True,
        null=True
    )
    wireless_lans = models.ManyToManyField(
        to='wireless.WirelessLAN',
        related_name='interfaces',
        blank=True,
        verbose_name=_('wireless LANs')
    )
    vrf = models.ForeignKey(
        to='ipam.VRF',
        on_delete=models.SET_NULL,
        related_name='interfaces',
        null=True,
        blank=True,
        verbose_name=_('VRF')
    )
    ip_addresses = GenericRelation(
        to='ipam.IPAddress',
        content_type_field='assigned_object_type',
        object_id_field='assigned_object_id',
        related_query_name='interface'
    )
    mac_addresses = GenericRelation(
        to='dcim.MACAddress',
        content_type_field='assigned_object_type',
        object_id_field='assigned_object_id',
        related_query_name='interface'
    )
    fhrp_group_assignments = GenericRelation(
        to='ipam.FHRPGroupAssignment',
        content_type_field='interface_type',
        object_id_field='interface_id',
        related_query_name='+'
    )
    tunnel_terminations = GenericRelation(
        to='vpn.TunnelTermination',
        content_type_field='termination_type',
        object_id_field='termination_id',
        related_query_name='interface'
    )
    l2vpn_terminations = GenericRelation(
        to='vpn.L2VPNTermination',
        content_type_field='assigned_object_type',
        object_id_field='assigned_object_id',
        related_query_name='interface',
    )

    clone_fields = (
        'device', 'module', 'parent', 'bridge', 'lag', 'type', 'mgmt_only', 'mtu', 'mode', 'speed', 'duplex', 'rf_role',
        'rf_channel', 'rf_channel_frequency', 'rf_channel_width', 'tx_power', 'poe_mode', 'poe_type', 'vrf',
    )

    class Meta(ModularComponentModel.Meta):
        ordering = ('device', CollateAsChar('_name'))
        verbose_name = _('interface')
        verbose_name_plural = _('interfaces')

    def clean(self):
        super().clean()

        # Virtual Interfaces cannot have a Cable attached
        if self.is_virtual and self.cable:
            raise ValidationError({
                'type': _("{display_type} interfaces cannot have a cable attached.").format(
                    display_type=self.get_type_display()
                )
            })

        # Virtual Interfaces cannot be marked as connected
        if self.is_virtual and self.mark_connected:
            raise ValidationError({
                'mark_connected': _("{display_type} interfaces cannot be marked as connected.".format(
                    display_type=self.get_type_display())
                )
            })

        # Parent validation

        # An interface cannot be its own parent
        if self.pk and self.parent_id == self.pk:
            raise ValidationError({'parent': _("An interface cannot be its own parent.")})

        # A physical interface cannot have a parent interface
        if self.type != InterfaceTypeChoices.TYPE_VIRTUAL and self.parent is not None:
            raise ValidationError({'parent': _("Only virtual interfaces may be assigned to a parent interface.")})

        # An interface's parent must belong to the same device or virtual chassis
        if self.parent and self.parent.device != self.device:
            if self.device.virtual_chassis is None:
                raise ValidationError({
                    'parent': _(
                        "The selected parent interface ({interface}) belongs to a different device ({device})"
                    ).format(interface=self.parent, device=self.parent.device)
                })
            if self.parent.device.virtual_chassis != self.device.virtual_chassis:
                raise ValidationError({
                    'parent': _(
                        "The selected parent interface ({interface}) belongs to {device}, which is not part of "
                        "virtual chassis {virtual_chassis}."
                    ).format(
                        interface=self.parent,
                        device=self.parent.device,
                        virtual_chassis=self.device.virtual_chassis
                    )
                })

        # Bridge validation

        # A bridged interface belongs to the same device or virtual chassis
        if self.bridge and self.bridge.device != self.device:
            if self.device.virtual_chassis is None:
                raise ValidationError({
                    'bridge': _(
                        "The selected bridge interface ({bridge}) belongs to a different device ({device})."
                    ).format(bridge=self.bridge, device=self.bridge.device)
                })
            if self.bridge.device.virtual_chassis != self.device.virtual_chassis:
                raise ValidationError({
                    'bridge': _(
                        "The selected bridge interface ({interface}) belongs to {device}, which is not part of virtual "
                        "chassis {virtual_chassis}."
                    ).format(
                        interface=self.bridge, device=self.bridge.device, virtual_chassis=self.device.virtual_chassis
                    )
                })

        # LAG validation

        # A virtual interface cannot have a parent LAG
        if self.type == InterfaceTypeChoices.TYPE_VIRTUAL and self.lag is not None:
            raise ValidationError({'lag': _("Virtual interfaces cannot have a parent LAG interface.")})

        # A LAG interface cannot be its own parent
        if self.pk and self.lag_id == self.pk:
            raise ValidationError({'lag': _("A LAG interface cannot be its own parent.")})

        # An interface's LAG must belong to the same device or virtual chassis
        if self.lag and self.lag.device != self.device:
            if self.device.virtual_chassis is None:
                raise ValidationError({
                    'lag': _(
                        "The selected LAG interface ({lag}) belongs to a different device ({device})."
                    ).format(lag=self.lag, device=self.lag.device)
                })
            if self.lag.device.virtual_chassis != self.device.virtual_chassis:
                raise ValidationError({
                    'lag': _(
                        "The selected LAG interface ({lag}) belongs to {device}, which is not part of virtual chassis "
                        "{virtual_chassis}.".format(
                            lag=self.lag, device=self.lag.device, virtual_chassis=self.device.virtual_chassis)
                    )
                })

        # Wireless validation

        # RF channel may only be set for wireless interfaces
        if self.rf_channel and not self.is_wireless:
            raise ValidationError({'rf_channel': _("Channel may be set only on wireless interfaces.")})

        # Validate channel frequency against interface type and selected channel (if any)
        if self.rf_channel_frequency:
            if not self.is_wireless:
                raise ValidationError({
                    'rf_channel_frequency': _("Channel frequency may be set only on wireless interfaces."),
                })
            if self.rf_channel and self.rf_channel_frequency != get_channel_attr(self.rf_channel, 'frequency'):
                raise ValidationError({
                    'rf_channel_frequency': _("Cannot specify custom frequency with channel selected."),
                })

        # Validate channel width against interface type and selected channel (if any)
        if self.rf_channel_width:
            if not self.is_wireless:
                raise ValidationError({'rf_channel_width': _("Channel width may be set only on wireless interfaces.")})
            if self.rf_channel and self.rf_channel_width != get_channel_attr(self.rf_channel, 'width'):
                raise ValidationError({'rf_channel_width': _("Cannot specify custom width with channel selected.")})

        # VLAN validation
        if not self.mode and self.untagged_vlan:
            raise ValidationError({'untagged_vlan': _("Interface mode does not support an untagged vlan.")})

        # Validate untagged VLAN
        if self.untagged_vlan and self.untagged_vlan.site not in [self.device.site, None]:
            raise ValidationError({
                'untagged_vlan': _(
                    "The untagged VLAN ({untagged_vlan}) must belong to the same site as the interface's parent "
                    "device, or it must be global."
                ).format(untagged_vlan=self.untagged_vlan)
            })

    def save(self, *args, **kwargs):

        # Set absolute channel attributes from selected options
        if self.rf_channel and not self.rf_channel_frequency:
            self.rf_channel_frequency = get_channel_attr(self.rf_channel, 'frequency')
        if self.rf_channel and not self.rf_channel_width:
            self.rf_channel_width = get_channel_attr(self.rf_channel, 'width')

        super().save(*args, **kwargs)

    @property
    def _occupied(self):
        return super()._occupied or bool(self.wireless_link_id)

    @property
    def is_wired(self):
        return not self.is_virtual and not self.is_wireless

    @property
    def is_virtual(self):
        return self.type in VIRTUAL_IFACE_TYPES

    @property
    def is_wireless(self):
        return self.type in WIRELESS_IFACE_TYPES

    @property
    def is_lag(self):
        return self.type == InterfaceTypeChoices.TYPE_LAG

    @property
    def is_bridge(self):
        return self.type == InterfaceTypeChoices.TYPE_BRIDGE

    @property
    def link(self):
        return self.cable or self.wireless_link

    @cached_property
    def link_peers(self):
        if self.cable:
            return super().link_peers
        if self.wireless_link:
            # Return the opposite side of the attached wireless link
            if self.wireless_link.interface_a == self:
                return [self.wireless_link.interface_b]
            return [self.wireless_link.interface_a]
        return []

    @property
    def l2vpn_termination(self):
        return self.l2vpn_terminations.first()

    @cached_property
    def connected_endpoints(self):
        # If this is a virtual interface, return the remote endpoint of the connected
        # virtual circuit, if any.
        if self.is_virtual and hasattr(self, 'virtual_circuit_termination'):
            return self.virtual_circuit_termination.peer_terminations
        return super().connected_endpoints


#
# Pass-through ports
#

class PortMapping(PortMappingBase):
    """
    Maps a FrontPort & position to a RearPort & position.
    """
    device = models.ForeignKey(
        to='dcim.Device',
        on_delete=models.CASCADE,
        related_name='port_mappings',
    )
    front_port = models.ForeignKey(
        to='dcim.FrontPort',
        on_delete=models.CASCADE,
        related_name='mappings',
    )
    rear_port = models.ForeignKey(
        to='dcim.RearPort',
        on_delete=models.CASCADE,
        related_name='mappings',
    )

    def clean(self):
        super().clean()

        # Both ports must belong to the same device
        if self.front_port.device_id != self.rear_port.device_id:
            raise ValidationError({
                "rear_port": _("Rear port ({rear_port}) must belong to the same device").format(
                    rear_port=self.rear_port
                )
            })

    def save(self, *args, **kwargs):
        # Associate the mapping with the parent Device
        self.device = self.front_port.device
        super().save(*args, **kwargs)


class FrontPort(ModularComponentModel, CabledObjectModel, TrackingModelMixin):
    """
    A pass-through port on the front of a Device.
    """
    type = models.CharField(
        verbose_name=_('type'),
        max_length=50,
        choices=PortTypeChoices
    )
    color = ColorField(
        verbose_name=_('color'),
        blank=True
    )
    positions = models.PositiveSmallIntegerField(
        verbose_name=_('positions'),
        default=1,
        validators=[
            MinValueValidator(PORT_POSITION_MIN),
            MaxValueValidator(PORT_POSITION_MAX)
        ],
    )

    clone_fields = ('device', 'type', 'color', 'positions')

    class Meta(ModularComponentModel.Meta):
        constraints = (
            models.UniqueConstraint(
                fields=('device', 'name'),
                name='%(app_label)s_%(class)s_unique_device_name'
            ),
        )
        verbose_name = _('front port')
        verbose_name_plural = _('front ports')

    def clean(self):
        super().clean()

        # Check that positions is greater than or equal to the number of associated RearPorts
        if not self._state.adding:
            mapping_count = self.mappings.count()
            if self.positions < mapping_count:
                raise ValidationError({
                    "positions": _(
                        "The number of positions cannot be less than the number of mapped rear ports ({count})"
                    ).format(count=mapping_count)
                })


class RearPort(ModularComponentModel, CabledObjectModel, TrackingModelMixin):
    """
    A pass-through port on the rear of a Device.
    """
    type = models.CharField(
        verbose_name=_('type'),
        max_length=50,
        choices=PortTypeChoices
    )
    color = ColorField(
        verbose_name=_('color'),
        blank=True
    )
    positions = models.PositiveSmallIntegerField(
        verbose_name=_('positions'),
        default=1,
        validators=[
            MinValueValidator(PORT_POSITION_MIN),
            MaxValueValidator(PORT_POSITION_MAX)
        ],
    )

    clone_fields = ('device', 'type', 'color', 'positions')

    class Meta(ModularComponentModel.Meta):
        verbose_name = _('rear port')
        verbose_name_plural = _('rear ports')

    def clean(self):
        super().clean()

        # Check that positions count is greater than or equal to the number of associated FrontPorts
        if not self._state.adding:
            mapping_count = self.mappings.count()
            if self.positions < mapping_count:
                raise ValidationError({
                    "positions": _(
                        "The number of positions cannot be less than the number of mapped front ports "
                        "({count})"
                    ).format(count=mapping_count)
                })


#
# Bays
#

class ModuleBay(ModularComponentModel, TrackingModelMixin, MPTTModel):
    """
    An empty space within a Device which can house a child device
    """
    parent = TreeForeignKey(
        to='self',
        on_delete=models.CASCADE,
        related_name='children',
        blank=True,
        null=True,
        editable=False,
        db_index=True
    )
    position = models.CharField(
        verbose_name=_('position'),
        max_length=30,
        blank=True,
        help_text=_('Identifier to reference when renaming installed components')
    )
    enabled = models.BooleanField(
        verbose_name=_('enabled'),
        default=True,
    )

    objects = TreeManager()

    clone_fields = ('device', 'enabled')

    class Meta(ModularComponentModel.Meta):
        # Empty tuple triggers Django migration detection for MPTT indexes
        # (see #21016, django-mptt/django-mptt#682)
        indexes = ()
        constraints = (
            models.UniqueConstraint(
                fields=('device', 'module', 'name'),
                name='%(app_label)s_%(class)s_unique_device_module_name'
            ),
        )
        verbose_name = _('module bay')
        verbose_name_plural = _('module bays')

    class MPTTMeta:
        order_insertion_by = ('name',)

    def clean(self):
        super().clean()

        # Check for recursion
        if module := self.module:
            module_bays = [self.pk]
            modules = []
            while module:
                if module.pk in modules or module.module_bay.pk in module_bays:
                    raise ValidationError(_("A module bay cannot belong to a module installed within it."))
                modules.append(module.pk)
                module_bays.append(module.module_bay.pk)
                module = module.module_bay.module if module.module_bay else None

    def save(self, *args, **kwargs):
        if self.module:
            self.parent = self.module.module_bay
        else:
            self.parent = None
        super().save(*args, **kwargs)

    @property
    def _occupied(self):
        """
        Indicates whether the module bay is occupied by a module.
        """
        return bool(not self.enabled or hasattr(self, 'installed_module'))


class DeviceBay(ComponentModel, TrackingModelMixin):
    """
    An empty space within a Device which can house a child device
    """
    installed_device = models.OneToOneField(
        to='dcim.Device',
        on_delete=models.SET_NULL,
        related_name='parent_bay',
        blank=True,
        null=True
    )
    enabled = models.BooleanField(
        verbose_name=_('enabled'),
        default=True,
    )

    clone_fields = ('device', 'enabled')

    class Meta(ComponentModel.Meta):
        verbose_name = _('device bay')
        verbose_name_plural = _('device bays')

    def clean(self):
        super().clean()

        # Validate that the parent Device can have DeviceBays
        if hasattr(self, 'device') and not self.device.device_type.is_parent_device:
            raise ValidationError(_("This type of device ({device_type}) does not support device bays.").format(
                device_type=self.device.device_type
            ))

        # Prevent installing a device into a disabled bay
        if self.installed_device and not self.enabled:
            current_installed_device_id = (
                DeviceBay.objects.filter(pk=self.pk).values_list('installed_device_id', flat=True).first()
            )
            if self.pk is None or current_installed_device_id != self.installed_device_id:
                raise ValidationError({
                    'installed_device': _("Cannot install a device in a disabled device bay.")
                })

        # Cannot install a device into itself, obviously
        if self.installed_device and getattr(self, 'device', None) == self.installed_device:
            raise ValidationError(_("Cannot install a device into itself."))

        # Check that the installed device is not already installed elsewhere
        if self.installed_device:
            current_bay = DeviceBay.objects.filter(installed_device=self.installed_device).first()
            if current_bay and current_bay != self:
                raise ValidationError({
                    'installed_device': _(
                        "Cannot install the specified device; device is already installed in {bay}."
                    ).format(bay=current_bay)
                })

    @property
    def _occupied(self):
        """
        Indicates whether the device bay is occupied by a child device.
        """
        return bool(not self.enabled or self.installed_device_id)


#
# Inventory items
#


class InventoryItemRole(OrganizationalModel):
    """
    Inventory items may optionally be assigned a functional role.
    """
    color = ColorField(
        verbose_name=_('color'),
        default=ColorChoices.COLOR_GREY
    )

    class Meta:
        ordering = ('name',)
        verbose_name = _('inventory item role')
        verbose_name_plural = _('inventory item roles')


class InventoryItem(MPTTModel, ComponentModel, TrackingModelMixin):
    """
    An InventoryItem represents a serialized piece of hardware within a Device, such as a line card or power supply.
    InventoryItems are used only for inventory purposes.
    """
    parent = TreeForeignKey(
        to='self',
        on_delete=models.CASCADE,
        related_name='child_items',
        blank=True,
        null=True,
        db_index=True
    )
    component_type = models.ForeignKey(
        to='contenttypes.ContentType',
        on_delete=models.PROTECT,
        related_name='+',
        blank=True,
        null=True
    )
    component_id = models.PositiveBigIntegerField(
        blank=True,
        null=True
    )
    component = GenericForeignKey(
        ct_field='component_type',
        fk_field='component_id'
    )
    status = models.CharField(
        verbose_name=_('status'),
        max_length=50,
        choices=InventoryItemStatusChoices,
        default=InventoryItemStatusChoices.STATUS_ACTIVE
    )
    role = models.ForeignKey(
        to='dcim.InventoryItemRole',
        on_delete=models.PROTECT,
        related_name='inventory_items',
        blank=True,
        null=True
    )
    manufacturer = models.ForeignKey(
        to='dcim.Manufacturer',
        on_delete=models.PROTECT,
        related_name='inventory_items',
        blank=True,
        null=True
    )
    part_id = models.CharField(
        max_length=50,
        verbose_name=_('part ID'),
        blank=True,
        help_text=_('Manufacturer-assigned part identifier')
    )
    serial = models.CharField(
        max_length=50,
        verbose_name=_('serial number'),
        blank=True
    )
    asset_tag = models.CharField(
        max_length=50,
        unique=True,
        blank=True,
        null=True,
        verbose_name=_('asset tag'),
        help_text=_('A unique tag used to identify this item')
    )
    discovered = models.BooleanField(
        verbose_name=_('discovered'),
        default=False,
        help_text=_('This item was automatically discovered')
    )

    objects = TreeManager()

    clone_fields = ('device', 'parent', 'role', 'manufacturer', 'status', 'part_id')

    class Meta:
        ordering = ('device__id', 'parent__id', 'name')
        indexes = (
            models.Index(fields=('component_type', 'component_id')),
        )
        constraints = (
            models.UniqueConstraint(
                fields=('device', 'parent', 'name'),
                name='%(app_label)s_%(class)s_unique_device_parent_name'
            ),
        )
        verbose_name = _('inventory item')
        verbose_name_plural = _('inventory items')

    def clean(self):
        super().clean()

        # An InventoryItem cannot be its own parent
        if self.pk and self.parent_id == self.pk:
            raise ValidationError({
                "parent": _("Cannot assign self as parent.")
            })

        # Validation for moving InventoryItems
        if not self._state.adding:
            # Cannot move an InventoryItem to another device if it has a parent
            if self.parent and self.parent.device != self.device:
                raise ValidationError({
                    "parent": _("Parent inventory item does not belong to the same device.")
                })

            # Prevent moving InventoryItems with children
            first_child = self.get_children().first()
            if first_child and first_child.device != self.device:
                raise ValidationError(_("Cannot move an inventory item with dependent children"))

            # When moving an InventoryItem to another device, remove any associated component
            if self.component and self.component.device != self.device:
                self.component = None
        else:
            if self.component and self.component.device != self.device:
                raise ValidationError({
                    "device": _("Cannot assign inventory item to component on another device")
                })

    def get_status_color(self):
        return InventoryItemStatusChoices.colors.get(self.status)