| 1 | .\" -*- Nroff -*- |
| 2 | .\" Copyright 1996, 1997 Massachusetts Institute of Technology |
| 3 | .\" |
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| 29 | .\" $FreeBSD: src/share/man/man9/ifnet.9,v 1.9.2.10 2003/06/15 02:22:30 hmp Exp $ |
| 30 | .\" |
| 31 | .Dd May 10, 2008 |
| 32 | .Dt IFNET 9 |
| 33 | .Os |
| 34 | .Sh NAME |
| 35 | .Nm ifnet , |
| 36 | .Nm ifaddr , |
| 37 | .Nm ifqueue , |
| 38 | .Nm if_data |
| 39 | .Nd kernel interfaces for manipulating network interfaces |
| 40 | .Sh SYNOPSIS |
| 41 | .In sys/types.h |
| 42 | .In sys/time.h |
| 43 | .In sys/socket.h |
| 44 | .In net/if.h |
| 45 | .In net/if_var.h |
| 46 | .In net/if_types.h |
| 47 | .\" |
| 48 | .Ss "Interface Manipulation Functions" |
| 49 | .Ft void |
| 50 | .Fn if_attach "struct ifnet *ifp" |
| 51 | .Ft void |
| 52 | .Fn if_down "struct ifnet *ifp" |
| 53 | .Ft int |
| 54 | .Fn ifioctl "struct socket *so" "u_long cmd" "caddr_t data" "struct proc *p" |
| 55 | .Ft int |
| 56 | .Fn ifpromisc "struct ifnet *ifp" "int pswitch" |
| 57 | .Ft int |
| 58 | .Fn if_allmulti "struct ifnet *ifp" "int amswitch" |
| 59 | .Ft "struct ifnet *" |
| 60 | .Fn ifunit "const char *name" |
| 61 | .Ft void |
| 62 | .Fn if_up "struct ifnet *ifp" |
| 63 | .\" |
| 64 | .Ss "Interface Address Functions" |
| 65 | .Ft "struct ifaddr *" |
| 66 | .Fn ifa_ifwithaddr "struct sockaddr *addr" |
| 67 | .Ft "struct ifaddr *" |
| 68 | .Fn ifa_ifwithdstaddr "struct sockaddr *addr" |
| 69 | .Ft "struct ifaddr *" |
| 70 | .Fn ifa_ifwithnet "struct sockaddr *addr" |
| 71 | .Ft "struct ifaddr *" |
| 72 | .Fn ifaof_ifpforaddr "struct sockaddr *addr" "struct ifnet *ifp" |
| 73 | .Fn IFAFREE "struct ifaddr *ifa" |
| 74 | .\" |
| 75 | .Ss "Interface Multicast Address Functions" |
| 76 | .Ft int |
| 77 | .Fn if_addmulti "struct ifnet *ifp" "struct sockaddr *sa" "struct ifmultiaddr **ifmap" |
| 78 | .Ft int |
| 79 | .Fn if_delmulti "struct ifnet *ifp" "struct sockaddr *sa" |
| 80 | .Ft "struct ifmultiaddr *" |
| 81 | .Fn ifmaof_ifpforaddr "struct sockaddr *addr" "struct ifnet *ifp" |
| 82 | .Ss "Output queue macros" |
| 83 | .Fn IF_DEQUEUE "struct ifqueue *ifq" "struct mbuf *m" |
| 84 | .\" |
| 85 | .Ss "struct ifnet Member Functions" |
| 86 | .Ft int |
| 87 | .Fo (*if_output) |
| 88 | .Fa "struct ifnet *ifp" "struct mbuf *m" |
| 89 | .Fa "struct sockaddr *dst" "struct rtentry *rt" |
| 90 | .Fc |
| 91 | .Ft void |
| 92 | .Fn (*if_input) "struct ifnet *ifp" "struct mbuf *m" |
| 93 | .Ft void |
| 94 | .Fn (*if_start) "struct ifnet *ifp" |
| 95 | .Ft int |
| 96 | .Fo (*if_ioctl) |
| 97 | .Fa "struct ifnet *ifp" "u_long command" "caddr_t data" "struct ucred *cr" |
| 98 | .Fc |
| 99 | .Ft void |
| 100 | .Fn (*if_watchdog) "struct ifnet *ifp" |
| 101 | .Ft void |
| 102 | .Fn (*if_init) "void *if_softc" |
| 103 | .Ft int |
| 104 | .Fo (*if_resolvemulti) |
| 105 | .Fa "struct ifnet *ifp" "struct sockaddr **retsa" "struct sockaddr *addr" |
| 106 | .Fc |
| 107 | .Ft void |
| 108 | .Fn (*if_poll) "struct ifnet *ifp" "enum poll_cmd cmd" "int count" |
| 109 | .Ss "struct ifaddr member function" |
| 110 | .Ft void |
| 111 | .Fo (*ifa_rtrequest) |
| 112 | .Fa "int cmd" "struct rtentry *rt" "struct sockaddr *dst" |
| 113 | .Fc |
| 114 | .\" |
| 115 | .Ss "Global Variables" |
| 116 | .Vt extern struct ifnethead ifnet ; |
| 117 | .Vt extern int if_index ; |
| 118 | .Vt extern int ifqmaxlen ; |
| 119 | .Sh DATA STRUCTURES |
| 120 | The kernel mechanisms for handling network interfaces reside primarily |
| 121 | in the |
| 122 | .Vt ifnet , if_data , ifaddr , |
| 123 | and |
| 124 | .Vt ifmultiaddr |
| 125 | structures in |
| 126 | .In net/if.h |
| 127 | and |
| 128 | .In net/if_var.h |
| 129 | and the functions named above and defined in |
| 130 | .Pa sys/net/if.c . |
| 131 | Those interfaces which are intended to be used by user programs |
| 132 | are defined in |
| 133 | .In net/if.h ; |
| 134 | these include the interface flags, the |
| 135 | .Vt if_data |
| 136 | structure, and the structures defining the appearance of |
| 137 | interface-related messages on the |
| 138 | .Xr route 4 |
| 139 | routing socket and in |
| 140 | .Xr sysctl 3 . |
| 141 | The header file |
| 142 | .In net/if_var.h |
| 143 | defines the kernel-internal interfaces, including the |
| 144 | .Vt ifnet , ifaddr , |
| 145 | and |
| 146 | .Vt ifmultiaddr |
| 147 | structures and the functions which manipulate them. |
| 148 | (A few user programs will need |
| 149 | .In net/if_var.h |
| 150 | because it is the prerequisite of some other header file like |
| 151 | .In netinet/if_ether.h . |
| 152 | Most references to those two files in particular can be replaced by |
| 153 | .In net/ethernet.h . ) |
| 154 | .Pp |
| 155 | The system keeps a linked list of interfaces using the |
| 156 | .Li TAILQ |
| 157 | macros defined in |
| 158 | .Xr queue 3 ; |
| 159 | this list is headed by a |
| 160 | .Vt "struct ifnethead" |
| 161 | called |
| 162 | .Va ifnet . |
| 163 | The elements of this list are of type |
| 164 | .Vt "struct ifnet" , |
| 165 | and most kernel routines which manipulate interface as such accept or |
| 166 | return pointers to these structures. |
| 167 | Each interface structure |
| 168 | contains an |
| 169 | .Vt if_data |
| 170 | structure, which contains statistics and identifying information used |
| 171 | by management programs, and which is exported to user programs by way |
| 172 | of the |
| 173 | .Xr ifmib 4 |
| 174 | branch of the |
| 175 | .Xr sysctl 3 |
| 176 | MIB. |
| 177 | Each interface also has a |
| 178 | .Li TAILQ |
| 179 | of interface addresses, described by |
| 180 | .Vt ifaddr |
| 181 | structures; the head of the queue is always an |
| 182 | .Dv AF_LINK |
| 183 | address |
| 184 | (see |
| 185 | .Xr link_addr 3 ) |
| 186 | describing the link layer implemented by the interface (if any). |
| 187 | (Some trivial interfaces do not provide any link layer addresses; |
| 188 | this structure, while still present, serves only to identify the |
| 189 | interface name and index.) |
| 190 | .Pp |
| 191 | Finally, those interfaces supporting reception of multicast datagrams |
| 192 | have a |
| 193 | .Li LIST |
| 194 | of multicast group memberships, described by |
| 195 | .Vt ifmultiaddr |
| 196 | structures. |
| 197 | These memberships are reference-counted. |
| 198 | .Pp |
| 199 | Interfaces are also associated with an output queue, defined as a |
| 200 | .Vt "struct ifqueue" ; |
| 201 | this structure is used to hold packets while the interface is in the |
| 202 | process of sending another. |
| 203 | .Ss The Vt ifnet Ss structure |
| 204 | The fields of |
| 205 | .Vt "struct ifnet" |
| 206 | are as follows: |
| 207 | .Bl -tag -width ".Va if_poll_slowq" -offset indent |
| 208 | .It Va if_softc |
| 209 | .Pq Vt "void *" |
| 210 | A pointer to the driver's private state block. |
| 211 | (Initialized by driver.) |
| 212 | .It Va if_link |
| 213 | .Pq Fn TAILQ_ENTRY ifnet |
| 214 | .Xr queue 3 |
| 215 | macro glue. |
| 216 | .It Va if_xname |
| 217 | .Pq Vt "char *" |
| 218 | The name of the interface, |
| 219 | (e.g., |
| 220 | .Dq Li fxp0 |
| 221 | or |
| 222 | .Dq Li lo0) . |
| 223 | (Initialized by driver.) |
| 224 | .It Va if_dname |
| 225 | .Pq Vt "const char *" |
| 226 | The name of the driver. |
| 227 | (Initialized by driver.) |
| 228 | .It Va if_dunit |
| 229 | .Pq Vt int |
| 230 | A unique number assigned to each interface managed by a particular |
| 231 | driver. |
| 232 | Drivers may choose to set this to |
| 233 | .Dv IF_DUNIT_NONE |
| 234 | if a unit number is not associated with the device. |
| 235 | (Initialized by driver.) |
| 236 | .\" .It Va if_vlantrunks |
| 237 | .\" .Pq Vt "void *" |
| 238 | .\" ... |
| 239 | .It Va if_addrhead |
| 240 | .Pq Vt "struct ifaddrhead" |
| 241 | The head of the |
| 242 | .Xr queue 3 |
| 243 | .Li TAILQ |
| 244 | containing the list of addresses assigned to this interface. |
| 245 | .It Va if_pcount |
| 246 | .Pq Vt int |
| 247 | A count of promiscuous listeners on this interface, used to |
| 248 | reference-count the |
| 249 | .Dv IFF_PROMISC |
| 250 | flag. |
| 251 | .It Va if_carp |
| 252 | .Pq Vt "struct carp_if *" |
| 253 | Per-interface data for |
| 254 | .Xr carp 4 . |
| 255 | .It Va if_bpf |
| 256 | .Pq Vt "struct bpf_if *" |
| 257 | Opaque per-interface data for the packet filter, |
| 258 | .Xr bpf 4 . |
| 259 | (Initialized by |
| 260 | .Fn bpfattach . ) |
| 261 | .It Va if_index |
| 262 | .Pq Vt u_short |
| 263 | A unique number assigned to each interface in sequence as it is |
| 264 | attached. |
| 265 | This number can be used in a |
| 266 | .Vt "struct sockaddr_dl" |
| 267 | to refer to a particular interface by index |
| 268 | (see |
| 269 | .Xr link_addr 3 ) . |
| 270 | .It Va if_timer |
| 271 | .Pq Vt short |
| 272 | Number of seconds until the watchdog timer |
| 273 | .Fn if_watchdog |
| 274 | is called, or zero if the timer is disabled. |
| 275 | (Set by driver, |
| 276 | decremented by generic watchdog code.) |
| 277 | .It Va if_flags |
| 278 | .Pq Vt int |
| 279 | Flags describing operational parameters of this interface (see below). |
| 280 | (Manipulated by both driver and generic code.) |
| 281 | .It Va if_linkmib |
| 282 | .Pq Vt "void *" |
| 283 | A pointer to an interface-specific MIB structure exported by |
| 284 | .Xr ifmib 4 . |
| 285 | (Initialized by driver.) |
| 286 | .It Va if_linkmiblen |
| 287 | .Pq Vt size_t |
| 288 | The size of said structure. |
| 289 | (Initialized by driver.) |
| 290 | .It Va if_data |
| 291 | .Pq Vt "struct if_data" |
| 292 | More statistics and information; see |
| 293 | .Sx "The if_data structure" , |
| 294 | below. |
| 295 | (Initialized by driver, manipulated by both driver and generic |
| 296 | code.) |
| 297 | .\" .It Va if_poll_cpuid |
| 298 | .\" .Pq Vt int |
| 299 | .\" ... |
| 300 | .It Va if_snd |
| 301 | .Pq Vt "struct ifaltq" |
| 302 | The output queue including |
| 303 | .Xr altq 4 . |
| 304 | (Manipulated by driver.) |
| 305 | .\" .It Va if_broadcastaddr |
| 306 | .\" .Pq Vt "const uint8_t" |
| 307 | .\" ... |
| 308 | .\" .It Va if_bridge |
| 309 | .\" .Pq Vt "void *" |
| 310 | .\" ... |
| 311 | .\" .It Va if_afdata |
| 312 | .\" .Pq Vt "void *" |
| 313 | .\" ... |
| 314 | .\" .It Va if_lladdr |
| 315 | .\" .Pq Vt "struct ifaddr" |
| 316 | .\" ... |
| 317 | .\" .It Va if_serializer |
| 318 | .\" .Pq Vt "struct lwkt_serialize" |
| 319 | .\" ... |
| 320 | .\" .It Va if_default_serializer |
| 321 | .\" .Pq Vt "struct lwkt_serialize" |
| 322 | .\" ... |
| 323 | .El |
| 324 | .Pp |
| 325 | There are in addition a number of function pointers which the driver |
| 326 | must initialize to complete its interface with the generic interface |
| 327 | layer: |
| 328 | .Bl -ohang -offset indent |
| 329 | .It Fn if_output |
| 330 | Output a packet on interface |
| 331 | .Fa ifp , |
| 332 | or queue it on the output queue if the interface is already active. |
| 333 | .It Fn if_start |
| 334 | Start queued output on an interface. |
| 335 | This function is exposed in |
| 336 | order to provide for some interface classes to share a |
| 337 | .Fn if_output |
| 338 | among all drivers. |
| 339 | .Fn if_start |
| 340 | may only be called when the |
| 341 | .Dv IFF_OACTIVE |
| 342 | flag is not set. |
| 343 | (Thus, |
| 344 | .Dv IFF_OACTIVE |
| 345 | does not literally mean that output is active, but rather that the |
| 346 | device's internal output queue is full.) |
| 347 | .It Fn if_ioctl |
| 348 | Process interface-related |
| 349 | .Xr ioctl 2 |
| 350 | requests |
| 351 | (defined in |
| 352 | .In sys/sockio.h ) . |
| 353 | Preliminary processing is done by the generic routine |
| 354 | .Fn ifioctl |
| 355 | to check for appropriate privileges, locate the interface being |
| 356 | manipulated, and perform certain generic operations like twiddling |
| 357 | flags and flushing queues. |
| 358 | See the description of |
| 359 | .Fn ifioctl |
| 360 | below for more information. |
| 361 | .It Fn if_watchdog |
| 362 | Routine called by the generic code when the watchdog timer, |
| 363 | .Va if_timer , |
| 364 | expires. |
| 365 | Usually this will reset the interface. |
| 366 | .\".It Fn if_poll |
| 367 | .\" See the |
| 368 | .\" .Sx POLLING |
| 369 | .\" section, below. |
| 370 | .It Fn if_init |
| 371 | Initialize and bring up the hardware, |
| 372 | e.g., reset the chip and the watchdog timer and enable the receiver unit. |
| 373 | Should mark the interface running, |
| 374 | but not active |
| 375 | .Dv ( IFF_RUNNING , ~IFF_OACTIVE ) . |
| 376 | .It Fn if_resolvemulti |
| 377 | Check the requested multicast group membership, |
| 378 | .Fa addr , |
| 379 | for validity, and if necessary compute a link-layer group which |
| 380 | corresponds to that address which is returned in |
| 381 | .Fa *retsa . |
| 382 | Returns zero on success, or an error code on failure. |
| 383 | .El |
| 384 | .Ss "Interface Flags" |
| 385 | Interface flags are used for a number of different purposes. |
| 386 | Some |
| 387 | flags simply indicate information about the type of interface and its |
| 388 | capabilities; others are dynamically manipulated to reflect the |
| 389 | current state of the interface. |
| 390 | Flags of the former kind are marked |
| 391 | .Aq S |
| 392 | in this table; the latter are marked |
| 393 | .Aq D . |
| 394 | .Pp |
| 395 | .Bl -tag -width ".Dv IFF_POINTOPOINT" -offset indent -compact |
| 396 | .It Dv IFF_UP |
| 397 | .Aq D |
| 398 | The interface has been configured up by the user-level code. |
| 399 | .It Dv IFF_BROADCAST |
| 400 | .Aq S* |
| 401 | The interface supports broadcast. |
| 402 | .It Dv IFF_DEBUG |
| 403 | .Aq D |
| 404 | Used to enable/disable driver debugging code. |
| 405 | .It Dv IFF_LOOPBACK |
| 406 | .Aq S |
| 407 | The interface is a loopback device. |
| 408 | .It Dv IFF_POINTOPOINT |
| 409 | .Aq S* |
| 410 | The interface is point-to-point; |
| 411 | .Dq broadcast |
| 412 | address is actually the address of the other end. |
| 413 | .It Dv IFF_RUNNING |
| 414 | .Aq D* |
| 415 | The interface has been configured and dynamic resources were |
| 416 | successfully allocated. |
| 417 | Probably only useful internal to the |
| 418 | interface. |
| 419 | .It Dv IFF_NOARP |
| 420 | .Aq D |
| 421 | Disable network address resolution on this interface. |
| 422 | .It Dv IFF_PROMISC |
| 423 | .Aq D* |
| 424 | This interface is in promiscuous mode. |
| 425 | .It Dv IFF_PPROMISC |
| 426 | .Aq D |
| 427 | This interface is in the permanently promiscuous mode (implies |
| 428 | .Dv IFF_PROMISC ) . |
| 429 | .It Dv IFF_ALLMULTI |
| 430 | .Aq D* |
| 431 | This interface is in all-multicasts mode (used by multicast routers). |
| 432 | .It Dv IFF_OACTIVE |
| 433 | .Aq D* |
| 434 | The interface's hardware output queue (if any) is full; output packets |
| 435 | are to be queued. |
| 436 | .It Dv IFF_SIMPLEX |
| 437 | .Aq S* |
| 438 | The interface cannot hear its own transmissions. |
| 439 | .It Dv IFF_LINK0 |
| 440 | .It Dv IFF_LINK1 |
| 441 | .It Dv IFF_LINK2 |
| 442 | .Aq D |
| 443 | Control flags for the link layer. |
| 444 | (Currently abused to select among |
| 445 | multiple physical layers on some devices.) |
| 446 | .It Dv IFF_MULTICAST |
| 447 | .Aq S* |
| 448 | This interface supports multicast. |
| 449 | .It Dv IFF_POLLING |
| 450 | The interface is in polling mode. |
| 451 | .\" .It Dv IFF_MONITOR |
| 452 | .\" ... |
| 453 | .El |
| 454 | .Pp |
| 455 | The macro |
| 456 | .Dv IFF_CANTCHANGE |
| 457 | defines the bits which cannot be set by a user program using the |
| 458 | .Dv SIOCSIFFLAGS |
| 459 | command to |
| 460 | .Xr ioctl 2 ; |
| 461 | these are indicated by an asterisk in the listing above. |
| 462 | .Ss The Vt if_data Ss Structure |
| 463 | In |
| 464 | .Bx 4.4 , |
| 465 | a subset of the interface information believed to be of interest to |
| 466 | management stations was segregated from the |
| 467 | .Vt ifnet |
| 468 | structure and moved into its own |
| 469 | .Vt if_data |
| 470 | structure to facilitate its use by user programs. |
| 471 | The following elements of the |
| 472 | .Vt if_data |
| 473 | structure are initialized by the interface and are not expected to change |
| 474 | significantly over the course of normal operation: |
| 475 | .Bl -tag -width ".Va ifi_lastchange" -offset indent |
| 476 | .It Va ifi_type |
| 477 | .Pq Vt u_char |
| 478 | The type of the interface, as defined in |
| 479 | .In net/if_types.h |
| 480 | and described below in the |
| 481 | .Sx "Interface Types" |
| 482 | section. |
| 483 | .It Va ifi_physical |
| 484 | .Pq Vt u_char |
| 485 | Intended to represent a selection of physical layers on devices which |
| 486 | support more than one; never implemented. |
| 487 | .It Va ifi_addrlen |
| 488 | .Pq Vt u_char |
| 489 | Length of a link-layer address on this device, or zero if there are |
| 490 | none. |
| 491 | Used to initialize the address length field in |
| 492 | .Vt sockaddr_dl |
| 493 | structures referring to this interface. |
| 494 | .It Va ifi_hdrlen |
| 495 | .Pq Vt u_char |
| 496 | Maximum length of any link-layer header which might be prepended by |
| 497 | the driver to a packet before transmission. |
| 498 | The generic code computes |
| 499 | the maximum over all interfaces and uses that value to influence the |
| 500 | placement of data in |
| 501 | .Vt mbuf Ns s |
| 502 | to attempt to ensure that there is always |
| 503 | sufficient space to prepend a link-layer header without allocating an |
| 504 | additional |
| 505 | .Vt mbuf . |
| 506 | .\" (See |
| 507 | .\" .Xr mbuf 9 . ) |
| 508 | .\" .It Va ifi_recvquota |
| 509 | .\" .Pq Vt u_char |
| 510 | .\" Number of packets the interface is permitted to receive at one time |
| 511 | .\" when in polled mode. |
| 512 | .\" .It Va ifi_xmitquota |
| 513 | .\" .Pq Vt u_char |
| 514 | .\" Number of packets the interface is permitted to queue for transmission |
| 515 | .\" at one time when in polled mode. |
| 516 | .\" There is some controversy over |
| 517 | .\" whether such a restriction makes any sense at all. |
| 518 | .It Va ifi_mtu |
| 519 | .Pq Vt u_long |
| 520 | The maximum transmission unit of the medium, exclusive of any |
| 521 | link-layer overhead. |
| 522 | .It Va ifi_metric |
| 523 | .Pq Vt u_long |
| 524 | A dimensionless metric interpreted by a user-mode routing process. |
| 525 | .It Va ifi_link_state |
| 526 | .Pq Vt u_long |
| 527 | The link state of the interface, either |
| 528 | .Dv LINK_STATE_UNKNOWN , |
| 529 | .Dv LINK_STATE_DOWN , |
| 530 | or |
| 531 | .Dv LINK_STATE_UP . |
| 532 | .It Va ifi_baudrate |
| 533 | .Pq Vt uint64_t |
| 534 | The line rate of the interface, in bits per second. |
| 535 | .El |
| 536 | .Pp |
| 537 | The structure additionally contains generic statistics applicable to a |
| 538 | variety of different interface types (except as noted, all members are |
| 539 | of type |
| 540 | .Vt u_long ) : |
| 541 | .Bl -tag -width ".Va ifi_lastchange" -offset indent |
| 542 | .It Va ifi_ipackets |
| 543 | Number of packets received. |
| 544 | .It Va ifi_ierrors |
| 545 | Number of receive errors detected (e.g., FCS errors, DMA overruns, |
| 546 | etc.). |
| 547 | More detailed breakdowns can often be had by way of a |
| 548 | link-specific MIB. |
| 549 | .It Va ifi_opackets |
| 550 | Number of packets transmitted. |
| 551 | .It Va ifi_oerrors |
| 552 | Number of output errors detected (e.g., late collisions, DMA overruns, |
| 553 | etc.). |
| 554 | More detailed breakdowns can often be had by way of a |
| 555 | link-specific MIB. |
| 556 | .It Va ifi_collisions |
| 557 | Total number of collisions detected on output for CSMA interfaces. |
| 558 | (This member is sometimes [ab]used by other types of interfaces for |
| 559 | other output error counts.) |
| 560 | .It Va ifi_ibytes |
| 561 | Total traffic received, in bytes. |
| 562 | .It Va ifi_obytes |
| 563 | Total traffic transmitted, in bytes. |
| 564 | .It Va ifi_imcasts |
| 565 | Number of packets received which were sent by link-layer multicast. |
| 566 | .It Va ifi_omcasts |
| 567 | Number of packets sent by link-layer multicast. |
| 568 | .It Va ifi_iqdrops |
| 569 | Number of packets dropped on input. |
| 570 | Rarely implemented. |
| 571 | .It Va ifi_noproto |
| 572 | Number of packets received for unknown network-layer protocol. |
| 573 | .It Va ifi_lastchange |
| 574 | .Pq Vt "struct timeval" |
| 575 | The time of the last administrative change to the interface (as required |
| 576 | for |
| 577 | .Tn SNMP ) . |
| 578 | .El |
| 579 | .Ss Interface Types |
| 580 | The header file |
| 581 | .In net/if_types.h |
| 582 | defines symbolic constants for a number of different types of |
| 583 | interfaces. |
| 584 | The most common are: |
| 585 | .Pp |
| 586 | .Bl -tag -offset indent -width ".Dv IFT_PROPVIRTUAL" -compact |
| 587 | .It Dv IFT_OTHER |
| 588 | none of the following |
| 589 | .It Dv IFT_ETHER |
| 590 | Ethernet |
| 591 | .It Dv IFT_ISO88023 |
| 592 | ISO 8802-3 CSMA/CD |
| 593 | .It Dv IFT_ISO88024 |
| 594 | ISO 8802-4 Token Bus |
| 595 | .It Dv IFT_ISO88025 |
| 596 | ISO 8802-5 Token Ring |
| 597 | .It Dv IFT_ISO88026 |
| 598 | ISO 8802-6 DQDB MAN |
| 599 | .It Dv IFT_FDDI |
| 600 | FDDI |
| 601 | .It Dv IFT_PPP |
| 602 | Internet Point-to-Point Protocol |
| 603 | .Pq Xr ppp 8 |
| 604 | .It Dv IFT_LOOP |
| 605 | The loopback |
| 606 | .Pq Xr lo 4 |
| 607 | interface |
| 608 | .It Dv IFT_SLIP |
| 609 | Serial Line IP |
| 610 | .It Dv IFT_PARA |
| 611 | Parallel-port IP |
| 612 | .Pq Dq Tn PLIP |
| 613 | .It Dv IFT_ATM |
| 614 | Asynchronous Transfer Mode |
| 615 | .El |
| 616 | .Ss The Vt ifaddr Ss Structure |
| 617 | Every interface is associated with a list |
| 618 | (or, rather, a |
| 619 | .Li TAILQ ) |
| 620 | of addresses, rooted at the interface structure's |
| 621 | .Va if_addrlist |
| 622 | member. |
| 623 | The first element in this list is always an |
| 624 | .Dv AF_LINK |
| 625 | address representing the interface itself; multi-access network |
| 626 | drivers should complete this structure by filling in their link-layer |
| 627 | addresses after calling |
| 628 | .Fn if_attach . |
| 629 | Other members of the structure represent network-layer addresses which |
| 630 | have been configured by means of the |
| 631 | .Dv SIOCAIFADDR |
| 632 | command to |
| 633 | .Xr ioctl 2 , |
| 634 | called on a socket of the appropriate protocol family. |
| 635 | The elements of this list consist of |
| 636 | .Vt ifaddr |
| 637 | structures. |
| 638 | Most protocols will declare their own protocol-specific |
| 639 | interface address structures, but all begin with a |
| 640 | .Vt "struct ifaddr" |
| 641 | which provides the most-commonly-needed functionality across all |
| 642 | protocols. |
| 643 | Interface addresses are reference-counted. |
| 644 | .Pp |
| 645 | The members of |
| 646 | .Vt "struct ifaddr" |
| 647 | are as follows: |
| 648 | .Bl -tag -width ".Va ifa_rtrequest" -offset indent |
| 649 | .It Va ifa_addr |
| 650 | .Pq Vt "struct sockaddr *" |
| 651 | The local address of the interface. |
| 652 | .It Va ifa_dstaddr |
| 653 | .Pq Vt "struct sockaddr *" |
| 654 | The remote address of point-to-point interfaces, and the broadcast |
| 655 | address of broadcast interfaces. |
| 656 | .Va ( ifa_broadaddr |
| 657 | is a macro for |
| 658 | .Va ifa_dstaddr . ) |
| 659 | .It Va ifa_netmask |
| 660 | .Pq Vt "struct sockaddr *" |
| 661 | The network mask for multi-access interfaces, and the confusion |
| 662 | generator for point-to-point interfaces. |
| 663 | .\" .It Va if_data |
| 664 | .\" .Pq Vt "struct if_data" |
| 665 | .\" ... |
| 666 | .It Va ifa_ifp |
| 667 | .Pq Vt "struct ifnet *" |
| 668 | A link back to the interface structure. |
| 669 | .It Va ifa_containers |
| 670 | .Pq Vt "struct ifaddr_container *" |
| 671 | A pointer to an array of |
| 672 | .Vt ifaddr_container |
| 673 | structures which hold per-CPU data. |
| 674 | .It Va ifa_rtrequest |
| 675 | See below. |
| 676 | .It Va ifa_flags |
| 677 | .Pq Vt u_short |
| 678 | Some of the flags which would be used for a route representing this |
| 679 | address in the route table. |
| 680 | .\" .It Va ifa_cpumask |
| 681 | .\" .Pq Vt cpumask_t |
| 682 | .\" ... |
| 683 | .It Va ifa_metric |
| 684 | .Pq Vt int |
| 685 | A metric associated with this interface address, for the use of some |
| 686 | external routing protocol. |
| 687 | .El |
| 688 | .Pp |
| 689 | References to |
| 690 | .Vt ifaddr |
| 691 | structures are gained manually, by incrementing the |
| 692 | .Va ifa_refcnt |
| 693 | member of the according |
| 694 | .Va ifa_containers |
| 695 | structure (such as by calling the |
| 696 | .Fn IFAREF |
| 697 | macro). |
| 698 | References are released by calling the |
| 699 | .Fn IFAFREE |
| 700 | macro. |
| 701 | .Pp |
| 702 | .Fn ifa_rtrequest |
| 703 | is a pointer to a function which receives callouts from the routing |
| 704 | code |
| 705 | .Pq Fn rtrequest |
| 706 | to perform link-layer-specific actions upon requests to add, resolve, |
| 707 | or delete routes. |
| 708 | The |
| 709 | .Fa cmd |
| 710 | argument indicates the request in question: |
| 711 | .Dv RTM_ADD , RTM_RESOLVE , |
| 712 | or |
| 713 | .Dv RTM_DELETE . |
| 714 | The |
| 715 | .Fa rt |
| 716 | argument is the route in question; the |
| 717 | .Fa dst |
| 718 | argument is the specific destination being manipulated |
| 719 | for |
| 720 | .Dv RTM_RESOLVE , |
| 721 | or a null pointer otherwise. |
| 722 | .Sh FUNCTIONS |
| 723 | The functions provided by the generic interface code can be divided |
| 724 | into two groups: those which manipulate interfaces, and those which |
| 725 | manipulate interface addresses. |
| 726 | In addition to these functions, there |
| 727 | may also be link-layer support routines which are used by a number of |
| 728 | drivers implementing a specific link layer over different hardware; |
| 729 | see the documentation for that link layer for more details. |
| 730 | .Ss The Vt ifmultiaddr Ss Structure |
| 731 | Every multicast-capable interface is associated with a list of |
| 732 | multicast group memberships, which indicate at a low level which |
| 733 | link-layer multicast addresses (if any) should be accepted, and at a |
| 734 | high level, in which network-layer multicast groups a user process has |
| 735 | expressed interest. |
| 736 | .Pp |
| 737 | The elements of the structure are as follows: |
| 738 | .Bl -tag -width ".Va ifma_refcount" -offset indent |
| 739 | .It Va ifma_link |
| 740 | .Pq Fn LIST_ENTRY ifmultiaddr |
| 741 | .Xr queue 3 |
| 742 | macro glue. |
| 743 | .It Va ifma_addr |
| 744 | .Pq Vt "struct sockaddr *" |
| 745 | A pointer to the address which this record represents. |
| 746 | The |
| 747 | memberships for various address families are stored in arbitrary |
| 748 | order. |
| 749 | .It Va ifma_lladdr |
| 750 | .Pq Vt "struct sockaddr *" |
| 751 | A pointer to the link-layer multicast address, if any, to which the |
| 752 | network-layer multicast address in |
| 753 | .Va ifma_addr |
| 754 | is mapped, else a null pointer. |
| 755 | If this element is non-nil, this |
| 756 | membership also holds an invisible reference to another membership for |
| 757 | that link-layer address. |
| 758 | .It Va ifma_refcount |
| 759 | .Pq Vt u_int |
| 760 | A reference count of requests for this particular membership. |
| 761 | .El |
| 762 | .Ss Interface Manipulation Functions |
| 763 | .Bl -ohang -offset indent |
| 764 | .It Fn if_attach |
| 765 | Link the specified interface |
| 766 | .Fa ifp |
| 767 | into the list of network interfaces. |
| 768 | Also initialize the list of |
| 769 | addresses on that interface, and create a link-layer |
| 770 | .Vt ifaddr |
| 771 | structure to be the first element in that list. |
| 772 | (A pointer to |
| 773 | this address structure is saved in the global array |
| 774 | .Va ifnet_addrs . ) |
| 775 | .It Fn if_down |
| 776 | Mark the interface |
| 777 | .Fa ifp |
| 778 | as down (i.e., |
| 779 | .Dv IFF_UP |
| 780 | is not set), |
| 781 | flush its output queue, notify protocols of the transition, |
| 782 | and generate a message from the |
| 783 | .Xr route 4 |
| 784 | routing socket. |
| 785 | .It Fn if_up |
| 786 | Mark the interface |
| 787 | .Fa ifp |
| 788 | as up, notify protocols of the transition, |
| 789 | and generate a message from the |
| 790 | .Xr route 4 |
| 791 | routing socket. |
| 792 | .It Fn ifpromisc |
| 793 | Add or remove a promiscuous reference to |
| 794 | .Fa ifp . |
| 795 | If |
| 796 | .Fa pswitch |
| 797 | is true, add a reference; |
| 798 | if it is false, remove a reference. |
| 799 | On reference count transitions |
| 800 | from zero to one and one to zero, set the |
| 801 | .Dv IFF_PROMISC |
| 802 | flag appropriately and call |
| 803 | .Fn if_ioctl |
| 804 | to set up the interface in the desired mode. |
| 805 | .It Fn if_allmulti |
| 806 | As |
| 807 | .Fn ifpromisc , |
| 808 | but for the all-multicasts |
| 809 | .Pq Dv IFF_ALLMULTI |
| 810 | flag instead of the promiscuous flag. |
| 811 | .It Fn ifunit |
| 812 | Return an |
| 813 | .Vt ifnet |
| 814 | pointer for the interface named |
| 815 | .Fa name . |
| 816 | .It Fn ifioctl |
| 817 | Process the ioctl request |
| 818 | .Fa cmd , |
| 819 | issued on socket |
| 820 | .Fa so |
| 821 | by process |
| 822 | .Fa p , |
| 823 | with data parameter |
| 824 | .Fa data . |
| 825 | This is the main routine for handling all interface configuration |
| 826 | requests from user mode. |
| 827 | It is ordinarily only called from the socket-layer |
| 828 | .Xr ioctl 2 |
| 829 | handler, and only for commands with class |
| 830 | .Sq Li i . |
| 831 | Any unrecognized commands will be passed down to socket |
| 832 | .Fa so Ns 's |
| 833 | protocol for |
| 834 | further interpretation. |
| 835 | The following commands are handled by |
| 836 | .Fn ifioctl : |
| 837 | .Pp |
| 838 | .Bl -tag -width ".Dv OSIOCGIFNETMASK" -offset indent -compact |
| 839 | .It Dv SIOCGIFCONF |
| 840 | .It Dv OSIOCGIFCONF |
| 841 | Get interface configuration. |
| 842 | (No call-down to driver.) |
| 843 | .Pp |
| 844 | .It Dv SIOCGIFFLAGS |
| 845 | .It Dv SIOCGIFMETRIC |
| 846 | .It Dv SIOCGIFMTU |
| 847 | .It Dv SIOCGIFPHYS |
| 848 | Get interface flags, metric, MTU, medium selection. |
| 849 | (No call-down to driver.) |
| 850 | .Pp |
| 851 | .It Dv SIOCSIFFLAGS |
| 852 | Change interface flags. |
| 853 | Caller must have appropriate privilege. |
| 854 | If a change to the |
| 855 | .Dv IFF_UP |
| 856 | flag is requested, |
| 857 | .Fn if_up |
| 858 | or |
| 859 | .Fn if_down |
| 860 | is called as appropriate. |
| 861 | Flags listed in |
| 862 | .Dv IFF_CANTCHANGE |
| 863 | are masked off, and the driver |
| 864 | .Fn if_ioctl |
| 865 | routine is called to perform any setup |
| 866 | requested. |
| 867 | .Pp |
| 868 | .It Dv SIOCSIFMETRIC |
| 869 | .It Dv SIOCSIFPHYS |
| 870 | Change interface metric or medium. |
| 871 | Caller must have appropriate privilege. |
| 872 | .Pp |
| 873 | .It Dv SIOCSIFMTU |
| 874 | Change interface MTU. |
| 875 | Caller must have appropriate privilege. |
| 876 | MTU |
| 877 | values less than 72 or greater than 65535 are considered invalid. |
| 878 | The driver |
| 879 | .Fn if_ioctl |
| 880 | routine is called to implement the change; it is responsible for any |
| 881 | additional sanity checking and for actually modifying the MTU in the |
| 882 | interface structure. |
| 883 | .Pp |
| 884 | .It Dv SIOCADDMULTI |
| 885 | .It Dv SIOCDELMULTI |
| 886 | Add or delete permanent multicast group memberships on the interface. |
| 887 | Caller must have appropriate privilege. |
| 888 | The |
| 889 | .Fn if_addmulti |
| 890 | or |
| 891 | .Fn if_delmulti |
| 892 | function is called to perform the operation; qq.v. |
| 893 | .Pp |
| 894 | .It Dv SIOCSIFDSTADDR |
| 895 | .It Dv SIOCSIFADDR |
| 896 | .It Dv SIOCSIFBRDADDR |
| 897 | .It Dv SIOCSIFNETMASK |
| 898 | The socket's protocol control routine is called to implement the |
| 899 | requested action. |
| 900 | .Pp |
| 901 | .It Dv OSIOCGIFADDR |
| 902 | .It Dv OSIOCGIFDSTADDR |
| 903 | .It Dv OSIOCGIFBRDADDR |
| 904 | .It Dv OSIOCGIFNETMASK |
| 905 | The socket's protocol control routine is called to implement the |
| 906 | requested action. |
| 907 | On return, |
| 908 | .Vt sockaddr |
| 909 | structures are converted into old-style (no |
| 910 | .Va sa_len |
| 911 | member). |
| 912 | .El |
| 913 | .El |
| 914 | .Pp |
| 915 | .Fn if_down , |
| 916 | .Fn ifioctl , |
| 917 | .Fn ifpromisc , |
| 918 | and |
| 919 | .Fn if_up |
| 920 | must be called inside a critical section. |
| 921 | .Ss "Interface Address Functions" |
| 922 | Several functions exist to look up an interface address structure |
| 923 | given an address. |
| 924 | .Fn ifa_ifwithaddr |
| 925 | returns an interface address with either a local address or a |
| 926 | broadcast address precisely matching the parameter |
| 927 | .Fa addr . |
| 928 | .Fn ifa_ifwithdstaddr |
| 929 | returns an interface address for a point-to-point interface whose |
| 930 | remote |
| 931 | .Pq Dq destination |
| 932 | address is |
| 933 | .Fa addr . |
| 934 | .Pp |
| 935 | .Fn ifa_ifwithnet |
| 936 | returns the most specific interface address which matches the |
| 937 | specified address, |
| 938 | .Fa addr , |
| 939 | subject to its configured netmask, or a point-to-point interface |
| 940 | address whose remote address is |
| 941 | .Fa addr |
| 942 | if one is found. |
| 943 | .Pp |
| 944 | .Fn ifaof_ifpforaddr |
| 945 | returns the most specific address configured on interface |
| 946 | .Fa ifp |
| 947 | which matches address |
| 948 | .Fa addr , |
| 949 | subject to its configured netmask. |
| 950 | If the interface is |
| 951 | point-to-point, only an interface address whose remote address is |
| 952 | precisely |
| 953 | .Fa addr |
| 954 | will be returned. |
| 955 | .Pp |
| 956 | All of these functions return a null pointer if no such address can be |
| 957 | found. |
| 958 | .Ss "Interface Multicast Address Functions" |
| 959 | The |
| 960 | .Fn if_addmulti , |
| 961 | .Fn if_delmulti , |
| 962 | and |
| 963 | .Fn ifmaof_ifpforaddr |
| 964 | functions provide support for requesting and relinquishing multicast |
| 965 | group memberships, and for querying an interface's membership list, |
| 966 | respectively. |
| 967 | The |
| 968 | .Fn if_addmulti |
| 969 | function takes a pointer to an interface, |
| 970 | .Fa ifp , |
| 971 | and a generic address, |
| 972 | .Fa sa . |
| 973 | It also takes a pointer to a |
| 974 | .Vt "struct ifmultiaddr *" |
| 975 | which is filled in on successful return with the address of the |
| 976 | group membership control block. |
| 977 | The |
| 978 | .Fn if_addmulti |
| 979 | function performs the following four-step process: |
| 980 | .Bl -enum -offset indent |
| 981 | .It |
| 982 | Call the interface's |
| 983 | .Fn if_resolvemulti |
| 984 | entry point to determine the link-layer address, if any, corresponding |
| 985 | to this membership request, and also to give the link layer an |
| 986 | opportunity to veto this membership request should it so desire. |
| 987 | .It |
| 988 | Check the interface's group membership list for a pre-existing |
| 989 | membership for this group. |
| 990 | If one is not found, allocate a new one; |
| 991 | if one is, increment its reference count. |
| 992 | .It |
| 993 | If the |
| 994 | .Fn if_resolvemulti |
| 995 | routine returned a link-layer address corresponding to the group, |
| 996 | repeat the previous step for that address as well. |
| 997 | .It |
| 998 | If the interface's multicast address filter needs to be changed |
| 999 | because a new membership was added, call the interface's |
| 1000 | .Fn if_ioctl |
| 1001 | routine |
| 1002 | (with a |
| 1003 | .Fa cmd |
| 1004 | argument of |
| 1005 | .Dv SIOCADDMULTI ) |
| 1006 | to request that it do so. |
| 1007 | .El |
| 1008 | .Pp |
| 1009 | The |
| 1010 | .Fn if_delmulti |
| 1011 | function, given an interface |
| 1012 | .Fa ifp |
| 1013 | and an address, |
| 1014 | .Fa sa , |
| 1015 | reverses this process. |
| 1016 | Both functions return zero on success, or a |
| 1017 | standard error number on failure. |
| 1018 | .Pp |
| 1019 | The |
| 1020 | .Fn ifmaof_ifpforaddr |
| 1021 | function examines the membership list of interface |
| 1022 | .Fa ifp |
| 1023 | for an address matching |
| 1024 | .Fa addr , |
| 1025 | and returns a pointer to that |
| 1026 | .Vt "struct ifmultiaddr" |
| 1027 | if one is found, else it returns a null pointer. |
| 1028 | .\" .Sh POLLING |
| 1029 | .\" XXX write me! |
| 1030 | .Sh SEE ALSO |
| 1031 | .Xr ioctl 2 , |
| 1032 | .Xr link_addr 3 , |
| 1033 | .Xr queue 3 , |
| 1034 | .Xr sysctl 3 , |
| 1035 | .Xr bpf 4 , |
| 1036 | .Xr ifmib 4 , |
| 1037 | .Xr lo 4 , |
| 1038 | .Xr netintro 4 , |
| 1039 | .Xr config 8 , |
| 1040 | .Xr ppp 8 , |
| 1041 | .\" .Xr mbuf 9 , |
| 1042 | .Xr rtentry 9 |
| 1043 | .Rs |
| 1044 | .%A Gary R. Wright |
| 1045 | .%A W. Richard Stevens |
| 1046 | .%B TCP/IP Illustrated |
| 1047 | .%V Vol. 2 |
| 1048 | .%O Addison-Wesley, ISBN 0-201-63354-X |
| 1049 | .Re |
| 1050 | .Sh AUTHORS |
| 1051 | This manual page was written by |
| 1052 | .An Garrett A. Wollman . |