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39 .Nd kernel interfaces for manipulating network interfaces
48 .Ss "Interface Manipulation Functions"
50 .Fn if_alloc "u_char type"
52 .Fn if_attach "struct ifnet *ifp"
54 .Fn if_detach "struct ifnet *ifp"
56 .Fn if_free "struct ifnet *ifp"
58 .Fn if_free_type "struct ifnet *ifp" "u_char type"
60 .Fn if_down "struct ifnet *ifp"
62 .Fn ifioctl "struct socket *so" "u_long cmd" "caddr_t data" "struct thread *td"
64 .Fn ifpromisc "struct ifnet *ifp" "int pswitch"
66 .Fn if_allmulti "struct ifnet *ifp" "int amswitch"
68 .Fn ifunit "const char *name"
70 .Fn ifunit_ref "const char *name"
72 .Fn if_up "struct ifnet *ifp"
74 .Ss "Interface Address Functions"
76 .Fn ifaddr_byindex "u_short idx"
78 .Fn ifa_ifwithaddr "struct sockaddr *addr"
80 .Fn ifa_ifwithdstaddr "struct sockaddr *addr"
82 .Fn ifa_ifwithnet "struct sockaddr *addr" "int ignore_ptp"
84 .Fn ifaof_ifpforaddr "struct sockaddr *addr" "struct ifnet *ifp"
86 .Fn ifa_ref "struct ifaddr *ifa"
88 .Fn ifa_free "struct ifaddr *ifa"
90 .Ss "Interface Multicast Address Functions"
92 .Fn if_addmulti "struct ifnet *ifp" "struct sockaddr *sa" "struct ifmultiaddr **ifmap"
94 .Fn if_delmulti "struct ifnet *ifp" "struct sockaddr *sa"
95 .Ft "struct ifmultiaddr *"
96 .Fn if_findmulti "struct ifnet *ifp" "struct sockaddr *sa"
97 .Ss "Output queue macros"
98 .Fn IF_DEQUEUE "struct ifqueue *ifq" "struct mbuf *m"
100 .Ss "struct ifnet Member Functions"
102 .Fn \*(lp*if_input\*(rp "struct ifnet *ifp" "struct mbuf *m"
104 .Fo \*(lp*if_output\*(rp
105 .Fa "struct ifnet *ifp" "struct mbuf *m"
106 .Fa "const struct sockaddr *dst" "struct route *ro"
109 .Fn \*(lp*if_start\*(rp "struct ifnet *ifp"
111 .Fn \*(lp*if_transmit\*(rp "struct ifnet *ifp" "struct mbuf *m"
113 .Fn \*(lp*if_qflush\*(rp "struct ifnet *ifp"
115 .Fn \*(lp*if_ioctl\*(rp "struct ifnet *ifp" "u_long cmd" "caddr_t data"
117 .Fn \*(lp*if_init\*(rp "void *if_softc"
119 .Fo \*(lp*if_resolvemulti\*(rp
120 .Fa "struct ifnet *ifp" "struct sockaddr **retsa" "struct sockaddr *addr"
122 .Ss "struct ifaddr member function"
124 .Fo \*(lp*ifa_rtrequest\*(rp
125 .Fa "int cmd" "struct rtentry *rt" "struct rt_addrinfo *info"
128 .Ss "Global Variables"
129 .Vt extern struct ifnethead ifnet ;
130 .\" extern struct ifindex_entry *ifindex_table ;
131 .Vt extern int if_index ;
132 .Vt extern int ifqmaxlen ;
134 The kernel mechanisms for handling network interfaces reside primarily
136 .Vt ifnet , if_data , ifaddr ,
143 and the functions named above and defined in
145 Those interfaces which are intended to be used by user programs
148 these include the interface flags, the
150 structure, and the structures defining the appearance of
151 interface-related messages on the
153 routing socket and in
157 defines the kernel-internal interfaces, including the
161 structures and the functions which manipulate them.
162 (A few user programs will need
164 because it is the prerequisite of some other header file like
165 .In netinet/if_ether.h .
166 Most references to those two files in particular can be replaced by
167 .In net/ethernet.h . )
169 The system keeps a linked list of interfaces using the
173 this list is headed by a
174 .Vt "struct ifnethead"
177 The elements of this list are of type
179 and most kernel routines which manipulate interface as such accept or
180 return pointers to these structures.
181 Each interface structure
184 structure used for statistics and information.
185 Each interface also has a
187 of interface addresses, described by
195 describing the link layer implemented by the interface (if any)
201 (Some trivial interfaces do not provide any link layer addresses;
202 this structure, while still present, serves only to identify the
203 interface name and index.)
205 Finally, those interfaces supporting reception of multicast datagrams
208 of multicast group memberships, described by
211 These memberships are reference-counted.
213 Interfaces are also associated with an output queue, defined as a
214 .Vt "struct ifqueue" ;
215 this structure is used to hold packets while the interface is in the
216 process of sending another.
218 .Ss The Vt ifnet Ss structure
222 .Bl -tag -width ".Va if_capabilities" -offset indent
225 A pointer to the driver's private state block.
226 (Initialized by driver.)
229 A pointer to the common data for the interface's layer 2 protocol.
233 .Pq Vt "struct vnet *"
234 A pointer to the virtual network stack instance.
238 .Pq Vt "struct vnet *"
239 A pointer to the parent virtual network stack, where this
245 .Pq Fn TAILQ_ENTRY ifnet
250 The name of the interface,
255 (Initialized by driver
257 .Fn if_initname ) . )
259 .Pq Vt "const char *"
260 The name of the driver.
261 (Initialized by driver
263 .Fn if_initname ) . )
266 A unique number assigned to each interface managed by a particular
268 Drivers may choose to set this to
270 if a unit number is not associated with the device.
271 (Initialized by driver
273 .Fn if_initname ) . )
280 .Pq Vt "struct ifaddrhead"
284 containing the list of addresses assigned to this interface.
287 A count of promiscuous listeners on this interface, used to
292 .Pq Vt "struct carp_if *"
293 A pointer to the CARP interface structure,
295 (Initialized by the driver-specific
299 .Pq Vt "struct bpf_if *"
300 Opaque per-interface data for the packet filter,
306 A unique number assigned to each interface in sequence as it is
308 This number can be used in a
309 .Vt "struct sockaddr_dl"
310 to refer to a particular interface by index
316 .Pq Vt struct ifvlantrunk *
317 A pointer to 802.1Q trunk structure,
319 (Initialized by the driver-specific
324 Flags describing operational parameters of this interface (see below).
325 (Manipulated by generic code.)
328 Flags describing operational status of this interface (see below).
329 (Manipulated by driver.)
330 .It Va if_capabilities
332 Flags describing the capabilities the interface supports (see below).
335 Flags describing the enabled capabilities of the interface (see below).
338 A pointer to an interface-specific MIB structure exported by
340 (Initialized by driver.)
343 The size of said structure.
344 (Initialized by driver.)
346 .Pq Vt "struct if_data"
347 More statistics and information; see
348 .Sx "The if_data structure" ,
350 (Initialized by driver, manipulated by both driver and generic
353 .Pq Vt struct ifmultihead
357 containing the list of multicast addresses assigned to this interface.
360 A number of multicast requests on this interface, used to
365 .Pq Vt "struct ifaddr *"
366 A pointer to the link-level interface address.
369 .\" .It Va if_llsoftc
371 .\" The purpose of the field is unclear.
373 .Pq Vt "struct ifaltq"
375 (Manipulated by driver.)
376 .It Va if_broadcastaddr
377 .Pq Vt "const u_int8_t *"
378 A link-level broadcast bytestring for protocols with variable address
382 A pointer to the bridge interface structure,
384 (Initialized by the driver-specific
388 .Pq Vt "struct label *"
389 A pointer to the MAC Framework label structure,
395 An address family dependent data region.
396 .It Va if_afdata_initialized
398 Used to track the current state of address family initialization.
399 .It Va if_afdata_lock
400 .Pq Vt "struct rwlock"
410 task scheduled for link state change events of the interface.
412 .Pq Vt "struct rwlock"
415 lock used to protect interface-related address lists.
417 .Pq Fn LIST_ENTRY ifnet
419 macro glue for the list of clonable network interfaces.
421 .Pq Fn TAILQ_HEAD ", ifg_list"
425 containing the list of groups per interface.
428 A pointer to the structure used for interface abstraction by
437 The type of the interface as it was at the time of its allocation.
438 It is used to cache the type passed to
442 it would not be changed by drivers.
447 structures are gained by calling the
449 function and released by calling the
452 They are used to allow kernel code walking global interface lists
459 There are in addition a number of function pointers which the driver
460 must initialize to complete its interface with the generic interface
462 .Bl -ohang -offset indent
464 Pass a packet to an appropriate upper layer as determined
465 from the link-layer header of the packet.
466 This routine is to be called from an interrupt handler or
467 used to emulate reception of a packet on this interface.
468 A single function implementing
470 can be shared among multiple drivers utilizing the same link-layer
471 framing, e.g., Ethernet.
473 Output a packet on interface
475 or queue it on the output queue if the interface is already active.
477 Transmit a packet on an interface or queue it if the interface is
479 This function will return
481 if the devices software and hardware queues are both full.
482 This function must be installed after
484 to override the default implementation.
485 This function is exposed in order to allow drivers to manage their own queues
486 and to reduce the latency caused by a frequently gratuitous enqueue / dequeue
488 The suggested internal software queueing mechanism is buf_ring.
490 Free mbufs in internally managed queues when the interface is marked down.
491 This function must be installed after
493 to override the default implementation.
494 This function is exposed in order to allow drivers to manage their own queues
495 and to reduce the latency caused by a frequently gratuitous enqueue / dequeue
497 The suggested internal software queueing mechanism is buf_ring.
499 Start queued output on an interface.
500 This function is exposed in
501 order to provide for some interface classes to share a
505 may only be called when the
510 does not literally mean that output is active, but rather that the
511 device's internal output queue is full.) Please note that this function
512 will soon be deprecated.
514 Process interface-related
519 Preliminary processing is done by the generic routine
521 to check for appropriate privileges, locate the interface being
522 manipulated, and perform certain generic operations like twiddling
523 flags and flushing queues.
524 See the description of
526 below for more information.
528 Initialize and bring up the hardware,
529 e.g., reset the chip and enable the receiver unit.
530 Should mark the interface running,
532 .Dv ( IFF_DRV_RUNNING , ~IIF_DRV_OACTIVE ) .
533 .It Fn if_resolvemulti
534 Check the requested multicast group membership,
536 for validity, and if necessary compute a link-layer group which
537 corresponds to that address which is returned in
539 Returns zero on success, or an error code on failure.
541 .Ss "Interface Flags"
542 Interface flags are used for a number of different purposes.
544 flags simply indicate information about the type of interface and its
545 capabilities; others are dynamically manipulated to reflect the
546 current state of the interface.
547 Flags of the former kind are marked
549 in this table; the latter are marked
551 Flags which begin with
555 all other flags are stored in
560 defines the bits which cannot be set by a user program using the
564 these are indicated by an asterisk
566 in the following listing.
568 .Bl -tag -width ".Dv IFF_POINTOPOINT" -offset indent -compact
571 The interface has been configured up by the user-level code.
574 The interface supports broadcast.
577 Used to enable/disable driver debugging code.
580 The interface is a loopback device.
581 .It Dv IFF_POINTOPOINT
583 The interface is point-to-point;
585 address is actually the address of the other end.
588 The interface manages its own routes, rather than using the generic
593 This is probably useful for serial lines.
594 .It Dv IFF_DRV_RUNNING
596 The interface has been configured and dynamic resources were
597 successfully allocated.
598 Probably only useful internal to the
602 Disable network address resolution on this interface.
605 This interface is in promiscuous mode.
608 This interface is in the permanently promiscuous mode (implies
612 This interface is in all-multicasts mode (used by multicast routers).
613 .It Dv IFF_DRV_OACTIVE
615 The interface's hardware output queue (if any) is full; output packets
619 The interface cannot hear its own transmissions.
624 Control flags for the link layer.
625 (Currently abused to select among
626 multiple physical layers on some devices.)
629 This interface supports multicast.
630 .It Dv IFF_CANTCONFIG
632 The interface is not configurable in a meaningful way.
635 interfaces registered at the interface list.
638 This interface blocks transmission of packets and discards incoming
639 packets after BPF processing.
640 Used to monitor network traffic but not interact
641 with the network in question.
644 Used to enable/disable ARP requests on this interface.
649 structure of this interface is being released and still has
654 Set when this interface is being renamed.
656 .Ss "Interface Capabilities Flags"
657 Interface capabilities are specialized features an interface may
659 These capabilities are very hardware-specific
660 and allow, when enabled,
661 to offload specific network processing to the interface
662 or to offer a particular feature for use by other kernel parts.
664 It should be stressed that a capability can be completely
665 uncontrolled (i.e., stay always enabled with no way to disable it)
666 or allow limited control over itself (e.g., depend on another
668 Such peculiarities are determined solely by the hardware and driver
669 of a particular interface.
670 Only the driver possesses
671 the knowledge on whether and how the interface capabilities
673 Consequently, capabilities flags in
675 should never be modified directly by kernel code other than
676 the interface driver.
681 is the dedicated means to attempt altering
684 Userland code shall use
687 The following capabilities are currently supported by the system:
688 .Bl -tag -width ".Dv IFCAP_POLLING_NOCOUNT" -offset indent
690 This interface can do checksum validation on receiving data.
691 Some interfaces do not have sufficient buffer storage to store frames
692 above a certain MTU-size completely.
693 The driver for the interface might disable hardware checksum validation
694 if the MTU is set above the hardcoded limit.
696 This interface can do checksum calculation on transmitting data.
699 .Pq Dv IFCAP_RXCSUM | IFCAP_TXCSUM .
701 This interface can be a network console.
702 .It Dv IFCAP_VLAN_MTU
705 driver can operate over this interface in software tagging mode
706 without having to decrease MTU on
708 interfaces below 1500 bytes.
709 This implies the ability of this interface to cope with frames somewhat
710 longer than permitted by the Ethernet specification.
711 .It Dv IFCAP_VLAN_HWTAGGING
712 This interface can do VLAN tagging on output and
713 demultiplex frames by their VLAN tag on input.
714 .It Dv IFCAP_JUMBO_MTU
715 This Ethernet interface can transmit and receive frames up to
718 This interface supports
720 See below for details.
721 .It Dv IFCAP_VLAN_HWCSUM
722 This interface can do checksum calculation on both transmitting
723 and receiving data on
728 This Ethernet interface supports TCP4 Segmentation offloading.
730 This Ethernet interface supports TCP6 Segmentation offloading.
733 .Pq Dv IFCAP_TSO4 | IFCAP_TSO6 .
735 This Ethernet interface supports TCP offloading.
737 This Ethernet interface supports TCP6 offloading.
740 .Pq Dv IFCAP_TOE4 | IFCAP_TOE6 .
741 .It Dv IFCAP_WOL_UCAST
742 This Ethernet interface supports waking up on any Unicast packet.
743 .It Dv IFCAP_WOL_MCAST
744 This Ethernet interface supports waking up on any Multicast packet.
745 .It Dv IFCAP_WOL_MAGIC
746 This Ethernet interface supports waking up on any Magic packet such
751 .Pq Dv IFCAP_WOL_UCAST | IFCAP_WOL_MCAST | IFCAP_WOL_MAGIC .
753 This Ethernet interface supports TCP4 Offload Engine.
755 This Ethernet interface supports TCP6 Offload Engine.
758 .Pq Dv IFCAP_TOE4 | IFCAP_TOE6 .
759 .It Dv IFCAP_VLAN_HWFILTER
760 This interface supports frame filtering in hardware on
763 .It Dv IFCAP_POLLING_NOCOUNT
764 The return value for the number of processed packets should be
765 skipped for this interface.
766 .It Dv IFCAP_VLAN_HWTSO
767 This interface supports TCP Segmentation offloading on
771 .It Dv IFCAP_LINKSTATE
772 This Ethernet interface supports dynamic link state changes.
775 The ability of advanced network interfaces to offload certain
776 computational tasks from the host CPU to the board is limited
778 Therefore a separate field associated with an interface
780 .Va ifnet.if_data.ifi_hwassist
782 keeps a detailed description of its enabled capabilities
783 specific to TCP/IP processing.
784 The TCP/IP module consults the field to see which tasks
787 packet by the interface.
788 The flags defined for that field are a superset of those for
789 .Va mbuf.m_pkthdr.csum_flags ,
791 .Bl -tag -width ".Dv CSUM_FRAGMENT" -offset indent
793 The interface will compute IP checksums.
795 The interface will compute TCP checksums.
797 The interface will compute UDP checksums.
799 The interface can compute a TCP or UDP checksum for a packet
800 fragmented by the host CPU.
801 Makes sense only along with
806 The interface will do the fragmentation of IP packets if necessary.
807 The host CPU does not need to care about MTU on this interface
808 as long as a packet to transmit through it is an IP one and it
809 does not exceed the size of the hardware buffer.
812 An interface notifies the TCP/IP module about the tasks
813 the former has performed on an
815 packet by setting the corresponding flags in the field
816 .Va mbuf.m_pkthdr.csum_flags
819 containing the packet.
824 The capability of a network interface to operate in
826 mode involves several flags in different
827 global variables and per-interface fields.
832 indicates support for
834 on the particular interface.
836 .Va if_capabilities ,
837 the same flag can be marked or cleared in the interface's
841 thus initiating switch of the interface to
845 The actual mode change is managed by the driver-specific
850 handler returns the number of packets processed.
851 .Ss The Vt if_data Ss Structure
854 structure contains statistics and identifying information used
855 by management programs, and which is exported to user programs by way
861 The following elements of the
863 structure are initialized by the interface and are not expected to change
864 significantly over the course of normal operation:
865 .Bl -tag -width ".Va ifi_lastchange" -offset indent
868 The type of the interface, as defined in
870 and described below in the
871 .Sx "Interface Types"
875 Intended to represent a selection of physical layers on devices which
876 support more than one; never implemented.
879 Length of a link-layer address on this device, or zero if there are
881 Used to initialized the address length field in
883 structures referring to this interface.
886 Maximum length of any link-layer header which might be prepended by
887 the driver to a packet before transmission.
888 The generic code computes
889 the maximum over all interfaces and uses that value to influence the
892 to attempt to ensure that there is always
893 sufficient space to prepend a link-layer header without allocating an
901 Allows some stabilization of the routing socket ABI in the face of
902 increases in the length of
906 The maximum transmission unit of the medium, exclusive of any
910 A dimensionless metric interpreted by a user-mode routing process.
913 The line rate of the interface, in bits per second.
916 A detailed interpretation of the capabilities
917 to offload computational tasks for
920 The interface driver must keep this field in accord with
925 The system uptime when interface was attached or the statistics
927 This is intended to be used to set the SNMP variable
928 .Va ifCounterDiscontinuityTime .
929 It may also be used to determine if two successive queries for an
930 interface of the same index have returned results for the same
934 The structure additionally contains generic statistics applicable to a
935 variety of different interface types (except as noted, all members are
938 .Bl -tag -width ".Va ifi_lastchange" -offset indent
939 .It Va ifi_link_state
941 The current link state of Ethernet interfaces.
943 .Sx Interface Link States
944 section for possible values.
946 Number of packets received.
948 Number of receive errors detected (e.g., FCS errors, DMA overruns,
950 More detailed breakdowns can often be had by way of a
953 Number of packets transmitted.
955 Number of output errors detected (e.g., late collisions, DMA overruns,
957 More detailed breakdowns can often be had by way of a
959 .It Va ifi_collisions
960 Total number of collisions detected on output for CSMA interfaces.
961 (This member is sometimes [ab]used by other types of interfaces for
962 other output error counts.)
964 Total traffic received, in bytes.
966 Total traffic transmitted, in bytes.
968 Number of packets received which were sent by link-layer multicast.
970 Number of packets sent by link-layer multicast.
972 Number of packets dropped on input.
975 Number of packets received for unknown network-layer protocol.
976 .It Va ifi_lastchange
977 .Pq Vt "struct timeval"
978 The time of the last administrative change to the interface (as required
985 defines symbolic constants for a number of different types of
989 .Bl -tag -offset indent -width ".Dv IFT_PROPVIRTUAL" -compact
991 none of the following
999 ISO 8802-5 Token Ring
1005 Internet Point-to-Point Protocol
1017 Asynchronous Transfer Mode
1021 .Ss Interface Link States
1022 The following link states are currently defined:
1024 .Bl -tag -offset indent -width ".Dv LINK_STATE_UNKNOWN" -compact
1025 .It Dv LINK_STATE_UNKNOWN
1026 The link is in an invalid or unknown state.
1027 .It Dv LINK_STATE_DOWN
1029 .It Dv LINK_STATE_UP
1032 .Ss The Vt ifaddr Ss Structure
1033 Every interface is associated with a list
1036 of addresses, rooted at the interface structure's
1039 The first element in this list is always an
1041 address representing the interface itself; multi-access network
1042 drivers should complete this structure by filling in their link-layer
1043 addresses after calling
1045 Other members of the structure represent network-layer addresses which
1046 have been configured by means of the
1050 called on a socket of the appropriate protocol family.
1051 The elements of this list consist of
1054 Most protocols will declare their own protocol-specific
1055 interface address structures, but all begin with a
1057 which provides the most-commonly-needed functionality across all
1059 Interface addresses are reference-counted.
1064 .Bl -tag -width ".Va ifa_rtrequest" -offset indent
1066 .Pq Vt "struct sockaddr *"
1067 The local address of the interface.
1069 .Pq Vt "struct sockaddr *"
1070 The remote address of point-to-point interfaces, and the broadcast
1071 address of broadcast interfaces.
1076 .Pq Vt "struct sockaddr *"
1077 The network mask for multi-access interfaces, and the confusion
1078 generator for point-to-point interfaces.
1080 .Pq Vt "struct ifnet *"
1081 A link back to the interface structure.
1083 .Pq Fn TAILQ_ENTRY ifaddr
1085 glue for list of addresses on each interface.
1086 .It Va ifa_rtrequest
1090 Some of the flags which would be used for a route representing this
1091 address in the route table.
1094 The reference count.
1097 A metric associated with this interface address, for the use of some
1098 external routing protocol.
1103 structures are gained by calling the
1105 function and released by calling the
1110 is a pointer to a function which receives callouts from the routing
1113 to perform link-layer-specific actions upon requests to add,
1117 argument indicates the request in question:
1123 argument is the route in question; the
1125 argument contains the specific destination being manipulated.
1127 The functions provided by the generic interface code can be divided
1128 into two groups: those which manipulate interfaces, and those which
1129 manipulate interface addresses.
1130 In addition to these functions, there
1131 may also be link-layer support routines which are used by a number of
1132 drivers implementing a specific link layer over different hardware;
1133 see the documentation for that link layer for more details.
1134 .Ss The Vt ifmultiaddr Ss Structure
1135 Every multicast-capable interface is associated with a list of
1136 multicast group memberships, which indicate at a low level which
1137 link-layer multicast addresses (if any) should be accepted, and at a
1138 high level, in which network-layer multicast groups a user process has
1141 The elements of the structure are as follows:
1142 .Bl -tag -width ".Va ifma_refcount" -offset indent
1144 .Pq Fn LIST_ENTRY ifmultiaddr
1148 .Pq Vt "struct sockaddr *"
1149 A pointer to the address which this record represents.
1151 memberships for various address families are stored in arbitrary
1154 .Pq Vt "struct sockaddr *"
1155 A pointer to the link-layer multicast address, if any, to which the
1156 network-layer multicast address in
1158 is mapped, else a null pointer.
1159 If this element is non-nil, this
1160 membership also holds an invisible reference to another membership for
1161 that link-layer address.
1162 .It Va ifma_refcount
1164 A reference count of requests for this particular membership.
1166 .Ss Interface Manipulation Functions
1167 .Bl -ohang -offset indent
1169 Allocate and initialize
1170 .Vt "struct ifnet" .
1171 Initialization includes the allocation of an interface index and may
1172 include the allocation of a
1174 specific structure in
1177 Link the specified interface
1179 into the list of network interfaces.
1180 Also initialize the list of
1181 addresses on that interface, and create a link-layer
1183 structure to be the first element in that list.
1185 this address structure is saved in the
1187 structure and shall be accessed by the
1192 must have been allocated by
1195 Shut down and unlink the specified
1197 from the interface list.
1202 The interface must have been previously detached if it was ever attached.
1206 except that the given
1210 instead of the type in
1212 This is intended for use with drivers that change their interface type.
1219 flush its output queue, notify protocols of the transition,
1220 and generate a message from the
1226 as up, notify protocols of the transition,
1227 and generate a message from the
1231 Add or remove a promiscuous reference to
1235 is true, add a reference;
1236 if it is false, remove a reference.
1237 On reference count transitions
1238 from zero to one and one to zero, set the
1240 flag appropriately and call
1242 to set up the interface in the desired mode.
1246 but for the all-multicasts
1248 flag instead of the promiscuous flag.
1252 pointer for the interface named
1255 Return a reference-counted (via
1258 pointer for the interface named
1260 This is the preferred function over
1262 The caller is responsible for releasing the reference with
1264 when it is finished with the ifnet.
1266 Process the ioctl request
1274 This is the main routine for handling all interface configuration
1275 requests from user mode.
1276 It is ordinarily only called from the socket-layer
1278 handler, and only for commands with class
1280 Any unrecognized commands will be passed down to socket
1283 further interpretation.
1284 The following commands are handled by
1287 .Bl -tag -width ".Dv OSIOCGIFNETMASK" -offset indent -compact
1290 Get interface configuration.
1291 (No call-down to driver.)
1294 Set the interface name.
1296 departure and arrival messages are sent so that
1297 routing code that relies on the interface name will update its interface
1299 Caller must have appropriate privilege.
1300 (No call-down to driver.)
1304 .It Dv SIOCGIFMETRIC
1307 Get interface capabilities, FIB, flags, metric, MTU, medium selection.
1308 (No call-down to driver.)
1311 Enable or disable interface capabilities.
1312 Caller must have appropriate privilege.
1313 Before a call to the driver-specific
1315 routine, the requested mask for enabled capabilities is checked
1316 against the mask of capabilities supported by the interface,
1317 .Va if_capabilities .
1318 Requesting to enable an unsupported capability is invalid.
1319 The rest is supposed to be done by the driver,
1320 which includes updating
1323 .Va if_data.ifi_hwassist
1328 Caller must have appropriate privilege.
1329 FIB values start at 0 and values greater or equals than
1331 are considered invalid.
1333 Change interface flags.
1334 Caller must have appropriate privilege.
1341 is called as appropriate.
1344 are masked off, and the field
1346 in the interface structure is updated.
1349 routine is called to perform any setup
1352 .It Dv SIOCSIFMETRIC
1354 Change interface metric or medium.
1355 Caller must have appropriate privilege.
1358 Change interface MTU.
1359 Caller must have appropriate privilege.
1361 values less than 72 or greater than 65535 are considered invalid.
1364 routine is called to implement the change; it is responsible for any
1365 additional sanity checking and for actually modifying the MTU in the
1366 interface structure.
1370 Add or delete permanent multicast group memberships on the interface.
1371 Caller must have appropriate privilege.
1376 function is called to perform the operation; qq.v.
1380 The socket's protocol control routine is called to implement the
1384 .It Dv OSIOCGIFDSTADDR
1385 .It Dv OSIOCGIFBRDADDR
1386 .It Dv OSIOCGIFNETMASK
1387 The socket's protocol control routine is called to implement the
1391 structures are converted into old-style (no
1405 .Ss "Interface Address Functions"
1406 Several functions exist to look up an interface address structure
1409 returns an interface address with either a local address or a
1410 broadcast address precisely matching the parameter
1412 .Fn ifa_ifwithdstaddr
1413 returns an interface address for a point-to-point interface whose
1420 returns the most specific interface address which matches the
1423 subject to its configured netmask, or a point-to-point interface
1424 address whose remote address is
1429 is true, skip point-to-point interface addresses.
1431 .Fn ifaof_ifpforaddr
1432 returns the most specific address configured on interface
1434 which matches address
1436 subject to its configured netmask.
1438 point-to-point, only an interface address whose remote address is
1444 returns the link-level address of the interface with the given index
1447 All of these functions return a null pointer if no such address can be
1449 .Ss "Interface Multicast Address Functions"
1455 functions provide support for requesting and relinquishing multicast
1456 group memberships, and for querying an interface's membership list,
1460 function takes a pointer to an interface,
1462 and a generic address,
1464 It also takes a pointer to a
1465 .Vt "struct ifmultiaddr *"
1466 which is filled in on successful return with the address of the
1467 group membership control block.
1470 function performs the following four-step process:
1471 .Bl -enum -offset indent
1473 Call the interface's
1475 entry point to determine the link-layer address, if any, corresponding
1476 to this membership request, and also to give the link layer an
1477 opportunity to veto this membership request should it so desire.
1479 Check the interface's group membership list for a pre-existing
1480 membership for this group.
1481 If one is not found, allocate a new one;
1482 if one is, increment its reference count.
1486 routine returned a link-layer address corresponding to the group,
1487 repeat the previous step for that address as well.
1489 If the interface's multicast address filter needs to be changed
1490 because a new membership was added, call the interface's
1497 to request that it do so.
1502 function, given an interface
1506 reverses this process.
1507 Both functions return zero on success, or a
1508 standard error number on failure.
1512 function examines the membership list of interface
1514 for an address matching
1516 and returns a pointer to that
1517 .Vt "struct ifmultiaddr"
1518 if one is found, else it returns a null pointer.
1535 .%A W. Richard Stevens
1536 .%B TCP/IP Illustrated
1538 .%O Addison-Wesley, ISBN 0-201-63354-X
1541 This manual page was written by
1542 .An Garrett A. Wollman .