xref: /freebsd/sys/net/if_var.h (revision 7afc53b8dfcc7d5897920ce6cc7e842fbb4ab813)
1 /*-
2  * Copyright (c) 1982, 1986, 1989, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	From: @(#)if.h	8.1 (Berkeley) 6/10/93
30  * $FreeBSD$
31  */
32 
33 #ifndef	_NET_IF_VAR_H_
34 #define	_NET_IF_VAR_H_
35 
36 /*
37  * Structures defining a network interface, providing a packet
38  * transport mechanism (ala level 0 of the PUP protocols).
39  *
40  * Each interface accepts output datagrams of a specified maximum
41  * length, and provides higher level routines with input datagrams
42  * received from its medium.
43  *
44  * Output occurs when the routine if_output is called, with three parameters:
45  *	(*ifp->if_output)(ifp, m, dst, rt)
46  * Here m is the mbuf chain to be sent and dst is the destination address.
47  * The output routine encapsulates the supplied datagram if necessary,
48  * and then transmits it on its medium.
49  *
50  * On input, each interface unwraps the data received by it, and either
51  * places it on the input queue of an internetwork datagram routine
52  * and posts the associated software interrupt, or passes the datagram to a raw
53  * packet input routine.
54  *
55  * Routines exist for locating interfaces by their addresses
56  * or for locating an interface on a certain network, as well as more general
57  * routing and gateway routines maintaining information used to locate
58  * interfaces.  These routines live in the files if.c and route.c
59  */
60 
61 #ifdef __STDC__
62 /*
63  * Forward structure declarations for function prototypes [sic].
64  */
65 struct	mbuf;
66 struct	thread;
67 struct	rtentry;
68 struct	rt_addrinfo;
69 struct	socket;
70 struct	ether_header;
71 struct	carp_if;
72 #endif
73 
74 #include <sys/queue.h>		/* get TAILQ macros */
75 
76 #ifdef _KERNEL
77 #include <sys/mbuf.h>
78 #include <sys/eventhandler.h>
79 #endif /* _KERNEL */
80 #include <sys/lock.h>		/* XXX */
81 #include <sys/mutex.h>		/* XXX */
82 #include <sys/event.h>		/* XXX */
83 #include <sys/_task.h>
84 
85 #define	IF_DUNIT_NONE	-1
86 
87 #include <altq/if_altq.h>
88 
89 TAILQ_HEAD(ifnethead, ifnet);	/* we use TAILQs so that the order of */
90 TAILQ_HEAD(ifaddrhead, ifaddr);	/* instantiation is preserved in the list */
91 TAILQ_HEAD(ifprefixhead, ifprefix);
92 TAILQ_HEAD(ifmultihead, ifmultiaddr);
93 
94 /*
95  * Structure defining a queue for a network interface.
96  */
97 struct	ifqueue {
98 	struct	mbuf *ifq_head;
99 	struct	mbuf *ifq_tail;
100 	int	ifq_len;
101 	int	ifq_maxlen;
102 	int	ifq_drops;
103 	struct	mtx ifq_mtx;
104 };
105 
106 /*
107  * Structure defining a network interface.
108  *
109  * (Would like to call this struct ``if'', but C isn't PL/1.)
110  */
111 
112 /*
113  * NB: For FreeBSD, it is assumed that each NIC driver's softc starts with
114  * one of these structures, typically held within an arpcom structure.
115  *
116  *	struct <foo>_softc {
117  *		struct arpcom {
118  *			struct  ifnet ac_if;
119  *			...
120  *		} <arpcom> ;
121  *		...
122  *	};
123  *
124  * The assumption is used in a number of places, including many
125  * files in sys/net, device drivers, and sys/dev/mii.c:miibus_attach().
126  *
127  * Unfortunately devices' softc are opaque, so we depend on this layout
128  * to locate the struct ifnet from the softc in the generic code.
129  *
130  */
131 struct ifnet {
132 	void	*if_softc;		/* pointer to driver state */
133 	TAILQ_ENTRY(ifnet) if_link; 	/* all struct ifnets are chained */
134 	char	if_xname[IFNAMSIZ];	/* external name (name + unit) */
135 	const char *if_dname;		/* driver name */
136 	int	if_dunit;		/* unit or IF_DUNIT_NONE */
137 	struct	ifaddrhead if_addrhead;	/* linked list of addresses per if */
138 		/*
139 		 * if_addrhead is the list of all addresses associated to
140 		 * an interface.
141 		 * Some code in the kernel assumes that first element
142 		 * of the list has type AF_LINK, and contains sockaddr_dl
143 		 * addresses which store the link-level address and the name
144 		 * of the interface.
145 		 * However, access to the AF_LINK address through this
146 		 * field is deprecated. Use ifaddr_byindex() instead.
147 		 */
148 	struct	knlist if_klist;	/* events attached to this if */
149 	int	if_pcount;		/* number of promiscuous listeners */
150 	struct	carp_if *if_carp;	/* carp interface structure */
151 	struct	bpf_if *if_bpf;		/* packet filter structure */
152 	u_short	if_index;		/* numeric abbreviation for this if  */
153 	short	if_timer;		/* time 'til if_watchdog called */
154 	u_short	if_nvlans;		/* number of active vlans */
155 	int	if_flags;		/* up/down, broadcast, etc. */
156 	int	if_capabilities;	/* interface capabilities */
157 	int	if_capenable;		/* enabled features */
158 	void	*if_linkmib;		/* link-type-specific MIB data */
159 	size_t	if_linkmiblen;		/* length of above data */
160 	struct	if_data if_data;
161 	struct	ifmultihead if_multiaddrs; /* multicast addresses configured */
162 	int	if_amcount;		/* number of all-multicast requests */
163 /* procedure handles */
164 	int	(*if_output)		/* output routine (enqueue) */
165 		(struct ifnet *, struct mbuf *, struct sockaddr *,
166 		     struct rtentry *);
167 	void	(*if_input)		/* input routine (from h/w driver) */
168 		(struct ifnet *, struct mbuf *);
169 	void	(*if_start)		/* initiate output routine */
170 		(struct ifnet *);
171 	int	(*if_ioctl)		/* ioctl routine */
172 		(struct ifnet *, u_long, caddr_t);
173 	void	(*if_watchdog)		/* timer routine */
174 		(struct ifnet *);
175 	void	(*if_init)		/* Init routine */
176 		(void *);
177 	int	(*if_resolvemulti)	/* validate/resolve multicast */
178 		(struct ifnet *, struct sockaddr **, struct sockaddr *);
179 	void	*if_spare1;		/* spare pointer 1 */
180 	void	*if_spare2;		/* spare pointer 2 */
181 	void	*if_spare3;		/* spare pointer 3 */
182 	u_int	if_spare_flags1;	/* spare flags 1 */
183 	u_int	if_spare_flags2;	/* spare flags 2 */
184 	struct  ifaltq if_snd;		/* output queue (includes altq) */
185 	const u_int8_t *if_broadcastaddr; /* linklevel broadcast bytestring */
186 
187 	void	*if_bridge;		/* bridge glue */
188 
189 	struct	lltable *lltables;	/* list of L3-L2 resolution tables */
190 
191 	struct	label *if_label;	/* interface MAC label */
192 
193 	/* these are only used by IPv6 */
194 	struct	ifprefixhead if_prefixhead; /* list of prefixes per if */
195 	void	*if_afdata[AF_MAX];
196 	int	if_afdata_initialized;
197 	struct	mtx if_afdata_mtx;
198 	struct	task if_starttask;	/* task for IFF_NEEDSGIANT */
199 	struct	task if_linktask;	/* task for link change events */
200 };
201 
202 typedef void if_init_f_t(void *);
203 
204 /*
205  * XXX These aliases are terribly dangerous because they could apply
206  * to anything.
207  */
208 #define	if_mtu		if_data.ifi_mtu
209 #define	if_type		if_data.ifi_type
210 #define if_physical	if_data.ifi_physical
211 #define	if_addrlen	if_data.ifi_addrlen
212 #define	if_hdrlen	if_data.ifi_hdrlen
213 #define	if_metric	if_data.ifi_metric
214 #define	if_link_state	if_data.ifi_link_state
215 #define	if_baudrate	if_data.ifi_baudrate
216 #define	if_hwassist	if_data.ifi_hwassist
217 #define	if_ipackets	if_data.ifi_ipackets
218 #define	if_ierrors	if_data.ifi_ierrors
219 #define	if_opackets	if_data.ifi_opackets
220 #define	if_oerrors	if_data.ifi_oerrors
221 #define	if_collisions	if_data.ifi_collisions
222 #define	if_ibytes	if_data.ifi_ibytes
223 #define	if_obytes	if_data.ifi_obytes
224 #define	if_imcasts	if_data.ifi_imcasts
225 #define	if_omcasts	if_data.ifi_omcasts
226 #define	if_iqdrops	if_data.ifi_iqdrops
227 #define	if_noproto	if_data.ifi_noproto
228 #define	if_lastchange	if_data.ifi_lastchange
229 #define if_recvquota	if_data.ifi_recvquota
230 #define	if_xmitquota	if_data.ifi_xmitquota
231 #define if_rawoutput(if, m, sa) if_output(if, m, sa, (struct rtentry *)NULL)
232 
233 /* for compatibility with other BSDs */
234 #define	if_addrlist	if_addrhead
235 #define	if_list		if_link
236 
237 /*
238  * Output queues (ifp->if_snd) and slow device input queues (*ifp->if_slowq)
239  * are queues of messages stored on ifqueue structures
240  * (defined above).  Entries are added to and deleted from these structures
241  * by these macros, which should be called with ipl raised to splimp().
242  */
243 #define IF_LOCK(ifq)		mtx_lock(&(ifq)->ifq_mtx)
244 #define IF_UNLOCK(ifq)		mtx_unlock(&(ifq)->ifq_mtx)
245 #define	IF_LOCK_ASSERT(ifq)	mtx_assert(&(ifq)->ifq_mtx, MA_OWNED)
246 #define	_IF_QFULL(ifq)		((ifq)->ifq_len >= (ifq)->ifq_maxlen)
247 #define	_IF_DROP(ifq)		((ifq)->ifq_drops++)
248 #define	_IF_QLEN(ifq)		((ifq)->ifq_len)
249 
250 #define	_IF_ENQUEUE(ifq, m) do { 				\
251 	(m)->m_nextpkt = NULL;					\
252 	if ((ifq)->ifq_tail == NULL) 				\
253 		(ifq)->ifq_head = m; 				\
254 	else 							\
255 		(ifq)->ifq_tail->m_nextpkt = m; 		\
256 	(ifq)->ifq_tail = m; 					\
257 	(ifq)->ifq_len++; 					\
258 } while (0)
259 
260 #define IF_ENQUEUE(ifq, m) do {					\
261 	IF_LOCK(ifq); 						\
262 	_IF_ENQUEUE(ifq, m); 					\
263 	IF_UNLOCK(ifq); 					\
264 } while (0)
265 
266 #define	_IF_PREPEND(ifq, m) do {				\
267 	(m)->m_nextpkt = (ifq)->ifq_head; 			\
268 	if ((ifq)->ifq_tail == NULL) 				\
269 		(ifq)->ifq_tail = (m); 				\
270 	(ifq)->ifq_head = (m); 					\
271 	(ifq)->ifq_len++; 					\
272 } while (0)
273 
274 #define IF_PREPEND(ifq, m) do {		 			\
275 	IF_LOCK(ifq); 						\
276 	_IF_PREPEND(ifq, m); 					\
277 	IF_UNLOCK(ifq); 					\
278 } while (0)
279 
280 #define	_IF_DEQUEUE(ifq, m) do { 				\
281 	(m) = (ifq)->ifq_head; 					\
282 	if (m) { 						\
283 		if (((ifq)->ifq_head = (m)->m_nextpkt) == NULL)	\
284 			(ifq)->ifq_tail = NULL; 		\
285 		(m)->m_nextpkt = NULL; 				\
286 		(ifq)->ifq_len--; 				\
287 	} 							\
288 } while (0)
289 
290 #define IF_DEQUEUE(ifq, m) do { 				\
291 	IF_LOCK(ifq); 						\
292 	_IF_DEQUEUE(ifq, m); 					\
293 	IF_UNLOCK(ifq); 					\
294 } while (0)
295 
296 #define	_IF_POLL(ifq, m)	((m) = (ifq)->ifq_head)
297 #define	IF_POLL(ifq, m)		_IF_POLL(ifq, m)
298 
299 #define _IF_DRAIN(ifq) do { 					\
300 	struct mbuf *m; 					\
301 	for (;;) { 						\
302 		_IF_DEQUEUE(ifq, m); 				\
303 		if (m == NULL) 					\
304 			break; 					\
305 		m_freem(m); 					\
306 	} 							\
307 } while (0)
308 
309 #define IF_DRAIN(ifq) do {					\
310 	IF_LOCK(ifq);						\
311 	_IF_DRAIN(ifq);						\
312 	IF_UNLOCK(ifq);						\
313 } while(0)
314 
315 #ifdef _KERNEL
316 /* interface address change event */
317 typedef void (*ifaddr_event_handler_t)(void *, struct ifnet *);
318 EVENTHANDLER_DECLARE(ifaddr_event, ifaddr_event_handler_t);
319 /* new interface arrival event */
320 typedef void (*ifnet_arrival_event_handler_t)(void *, struct ifnet *);
321 EVENTHANDLER_DECLARE(ifnet_arrival_event, ifnet_arrival_event_handler_t);
322 /* interface departure event */
323 typedef void (*ifnet_departure_event_handler_t)(void *, struct ifnet *);
324 EVENTHANDLER_DECLARE(ifnet_departure_event, ifnet_departure_event_handler_t);
325 
326 #define	IF_AFDATA_LOCK_INIT(ifp)	\
327     mtx_init(&(ifp)->if_afdata_mtx, "if_afdata", NULL, MTX_DEF)
328 #define	IF_AFDATA_LOCK(ifp)	mtx_lock(&(ifp)->if_afdata_mtx)
329 #define	IF_AFDATA_TRYLOCK(ifp)	mtx_trylock(&(ifp)->if_afdata_mtx)
330 #define	IF_AFDATA_UNLOCK(ifp)	mtx_unlock(&(ifp)->if_afdata_mtx)
331 #define	IF_AFDATA_DESTROY(ifp)	mtx_destroy(&(ifp)->if_afdata_mtx)
332 
333 #define	IFF_LOCKGIANT(ifp) do {						\
334 	if ((ifp)->if_flags & IFF_NEEDSGIANT)				\
335 		mtx_lock(&Giant);					\
336 } while (0)
337 
338 #define	IFF_UNLOCKGIANT(ifp) do {					\
339 	if ((ifp)->if_flags & IFF_NEEDSGIANT)				\
340 		mtx_unlock(&Giant);					\
341 } while (0)
342 
343 int	if_handoff(struct ifqueue *ifq, struct mbuf *m, struct ifnet *ifp,
344 	    int adjust);
345 #define	IF_HANDOFF(ifq, m, ifp)			\
346 	if_handoff((struct ifqueue *)ifq, m, ifp, 0)
347 #define	IF_HANDOFF_ADJ(ifq, m, ifp, adj)	\
348 	if_handoff((struct ifqueue *)ifq, m, ifp, adj)
349 
350 void	if_start(struct ifnet *);
351 
352 #define	IFQ_ENQUEUE(ifq, m, err)					\
353 do {									\
354 	IF_LOCK(ifq);							\
355 	if (ALTQ_IS_ENABLED(ifq))					\
356 		ALTQ_ENQUEUE(ifq, m, NULL, err);			\
357 	else {								\
358 		if (_IF_QFULL(ifq)) {					\
359 			m_freem(m);					\
360 			(err) = ENOBUFS;				\
361 		} else {						\
362 			_IF_ENQUEUE(ifq, m);				\
363 			(err) = 0;					\
364 		}							\
365 	}								\
366 	if (err)							\
367 		(ifq)->ifq_drops++;					\
368 	IF_UNLOCK(ifq);							\
369 } while (0)
370 
371 #define	IFQ_DEQUEUE_NOLOCK(ifq, m)					\
372 do {									\
373 	if (TBR_IS_ENABLED(ifq))					\
374 		(m) = tbr_dequeue_ptr(ifq, ALTDQ_REMOVE);		\
375 	else if (ALTQ_IS_ENABLED(ifq))					\
376 		ALTQ_DEQUEUE(ifq, m);					\
377 	else								\
378 		_IF_DEQUEUE(ifq, m);					\
379 } while (0)
380 
381 #define	IFQ_DEQUEUE(ifq, m)						\
382 do {									\
383 	IF_LOCK(ifq);							\
384 	IFQ_DEQUEUE_NOLOCK(ifq, m);					\
385 	IF_UNLOCK(ifq);							\
386 } while (0)
387 
388 #define	IFQ_POLL_NOLOCK(ifq, m)						\
389 do {									\
390 	if (TBR_IS_ENABLED(ifq))					\
391 		(m) = tbr_dequeue_ptr(ifq, ALTDQ_POLL);			\
392 	else if (ALTQ_IS_ENABLED(ifq))					\
393 		ALTQ_POLL(ifq, m);					\
394 	else								\
395 		_IF_POLL(ifq, m);					\
396 } while (0)
397 
398 #define	IFQ_POLL(ifq, m)						\
399 do {									\
400 	IF_LOCK(ifq);							\
401 	IFQ_POLL_NOLOCK(ifq, m);					\
402 	IF_UNLOCK(ifq);							\
403 } while (0)
404 
405 #define	IFQ_PURGE_NOLOCK(ifq)						\
406 do {									\
407 	if (ALTQ_IS_ENABLED(ifq)) {					\
408 		ALTQ_PURGE(ifq);					\
409 	} else								\
410 		_IF_DRAIN(ifq);						\
411 } while (0)
412 
413 #define	IFQ_PURGE(ifq)							\
414 do {									\
415 	IF_LOCK(ifq);							\
416 	IFQ_PURGE_NOLOCK(ifq);						\
417 	IF_UNLOCK(ifq);							\
418 } while (0)
419 
420 #define	IFQ_SET_READY(ifq)						\
421 	do { ((ifq)->altq_flags |= ALTQF_READY); } while (0)
422 
423 #define	IFQ_LOCK(ifq)			IF_LOCK(ifq)
424 #define	IFQ_UNLOCK(ifq)			IF_UNLOCK(ifq)
425 #define	IFQ_LOCK_ASSERT(ifq)		IF_LOCK_ASSERT(ifq)
426 #define	IFQ_IS_EMPTY(ifq)		((ifq)->ifq_len == 0)
427 #define	IFQ_INC_LEN(ifq)		((ifq)->ifq_len++)
428 #define	IFQ_DEC_LEN(ifq)		(--(ifq)->ifq_len)
429 #define	IFQ_INC_DROPS(ifq)		((ifq)->ifq_drops++)
430 #define	IFQ_SET_MAXLEN(ifq, len)	((ifq)->ifq_maxlen = (len))
431 
432 #define	IFQ_HANDOFF_ADJ(ifp, m, adj, err)				\
433 do {									\
434 	int len;							\
435 	short mflags;							\
436 									\
437 	len = (m)->m_pkthdr.len;					\
438 	mflags = (m)->m_flags;						\
439 	IFQ_ENQUEUE(&(ifp)->if_snd, m, err);				\
440 	if ((err) == 0) {						\
441 		(ifp)->if_obytes += len + (adj);			\
442 		if (mflags & M_MCAST)					\
443 			(ifp)->if_omcasts++;				\
444 		if (((ifp)->if_flags & IFF_OACTIVE) == 0)		\
445 			if_start(ifp);					\
446 	}								\
447 } while (0)
448 
449 #define	IFQ_HANDOFF(ifp, m, err)					\
450 	IFQ_HANDOFF_ADJ(ifp, m, 0, err)
451 
452 #define	IFQ_DRV_DEQUEUE(ifq, m)						\
453 do {									\
454 	(m) = (ifq)->ifq_drv_head;					\
455 	if (m) {							\
456 		if (((ifq)->ifq_drv_head = (m)->m_nextpkt) == NULL)	\
457 			(ifq)->ifq_drv_tail = NULL;			\
458 		(m)->m_nextpkt = NULL;					\
459 		(ifq)->ifq_drv_len--;					\
460 	} else {							\
461 		IFQ_LOCK(ifq);						\
462 		IFQ_DEQUEUE_NOLOCK(ifq, m);				\
463 		while ((ifq)->ifq_drv_len < (ifq)->ifq_drv_maxlen) {	\
464 			struct mbuf *m0;				\
465 			IFQ_DEQUEUE_NOLOCK(ifq, m0);			\
466 			if (m0 == NULL)					\
467 				break;					\
468 			m0->m_nextpkt = NULL;				\
469 			if ((ifq)->ifq_drv_tail == NULL)		\
470 				(ifq)->ifq_drv_head = m0;		\
471 			else						\
472 				(ifq)->ifq_drv_tail->m_nextpkt = m0;	\
473 			(ifq)->ifq_drv_tail = m0;			\
474 			(ifq)->ifq_drv_len++;				\
475 		}							\
476 		IFQ_UNLOCK(ifq);					\
477 	}								\
478 } while (0)
479 
480 #define	IFQ_DRV_PREPEND(ifq, m)						\
481 do {									\
482 	(m)->m_nextpkt = (ifq)->ifq_drv_head;				\
483 	if ((ifq)->ifq_drv_tail == NULL)				\
484 		(ifq)->ifq_drv_tail = (m);				\
485 	(ifq)->ifq_drv_head = (m);					\
486 	(ifq)->ifq_drv_len++;						\
487 } while (0)
488 
489 #define	IFQ_DRV_IS_EMPTY(ifq)						\
490 	(((ifq)->ifq_drv_len == 0) && ((ifq)->ifq_len == 0))
491 
492 #define	IFQ_DRV_PURGE(ifq)						\
493 do {									\
494 	struct mbuf *m, *n = (ifq)->ifq_drv_head;			\
495 	while((m = n) != NULL) {					\
496 		n = m->m_nextpkt;					\
497 		m_freem(m);						\
498 	}								\
499 	(ifq)->ifq_drv_head = (ifq)->ifq_drv_tail = NULL;		\
500 	(ifq)->ifq_drv_len = 0;						\
501 	IFQ_PURGE(ifq);							\
502 } while (0)
503 
504 /*
505  * 72 was chosen below because it is the size of a TCP/IP
506  * header (40) + the minimum mss (32).
507  */
508 #define	IF_MINMTU	72
509 #define	IF_MAXMTU	65535
510 
511 #endif /* _KERNEL */
512 
513 /*
514  * The ifaddr structure contains information about one address
515  * of an interface.  They are maintained by the different address families,
516  * are allocated and attached when an address is set, and are linked
517  * together so all addresses for an interface can be located.
518  *
519  * NOTE: a 'struct ifaddr' is always at the beginning of a larger
520  * chunk of malloc'ed memory, where we store the three addresses
521  * (ifa_addr, ifa_dstaddr and ifa_netmask) referenced here.
522  */
523 struct ifaddr {
524 	struct	sockaddr *ifa_addr;	/* address of interface */
525 	struct	sockaddr *ifa_dstaddr;	/* other end of p-to-p link */
526 #define	ifa_broadaddr	ifa_dstaddr	/* broadcast address interface */
527 	struct	sockaddr *ifa_netmask;	/* used to determine subnet */
528 	struct	if_data if_data;	/* not all members are meaningful */
529 	struct	ifnet *ifa_ifp;		/* back-pointer to interface */
530 	TAILQ_ENTRY(ifaddr) ifa_link;	/* queue macro glue */
531 	void	(*ifa_rtrequest)	/* check or clean routes (+ or -)'d */
532 		(int, struct rtentry *, struct rt_addrinfo *);
533 	u_short	ifa_flags;		/* mostly rt_flags for cloning */
534 	u_int	ifa_refcnt;		/* references to this structure */
535 	int	ifa_metric;		/* cost of going out this interface */
536 	int (*ifa_claim_addr)		/* check if an addr goes to this if */
537 		(struct ifaddr *, struct sockaddr *);
538 	struct mtx ifa_mtx;
539 };
540 #define	IFA_ROUTE	RTF_UP		/* route installed */
541 
542 /* for compatibility with other BSDs */
543 #define	ifa_list	ifa_link
544 
545 #define	IFA_LOCK_INIT(ifa)	\
546     mtx_init(&(ifa)->ifa_mtx, "ifaddr", NULL, MTX_DEF)
547 #define	IFA_LOCK(ifa)		mtx_lock(&(ifa)->ifa_mtx)
548 #define	IFA_UNLOCK(ifa)		mtx_unlock(&(ifa)->ifa_mtx)
549 #define	IFA_DESTROY(ifa)	mtx_destroy(&(ifa)->ifa_mtx)
550 
551 /*
552  * The prefix structure contains information about one prefix
553  * of an interface.  They are maintained by the different address families,
554  * are allocated and attached when a prefix or an address is set,
555  * and are linked together so all prefixes for an interface can be located.
556  */
557 struct ifprefix {
558 	struct	sockaddr *ifpr_prefix;	/* prefix of interface */
559 	struct	ifnet *ifpr_ifp;	/* back-pointer to interface */
560 	TAILQ_ENTRY(ifprefix) ifpr_list; /* queue macro glue */
561 	u_char	ifpr_plen;		/* prefix length in bits */
562 	u_char	ifpr_type;		/* protocol dependent prefix type */
563 };
564 
565 /*
566  * Multicast address structure.  This is analogous to the ifaddr
567  * structure except that it keeps track of multicast addresses.
568  * Also, the reference count here is a count of requests for this
569  * address, not a count of pointers to this structure.
570  */
571 struct ifmultiaddr {
572 	TAILQ_ENTRY(ifmultiaddr) ifma_link; /* queue macro glue */
573 	struct	sockaddr *ifma_addr; 	/* address this membership is for */
574 	struct	sockaddr *ifma_lladdr;	/* link-layer translation, if any */
575 	struct	ifnet *ifma_ifp;	/* back-pointer to interface */
576 	u_int	ifma_refcount;		/* reference count */
577 	void	*ifma_protospec;	/* protocol-specific state, if any */
578 };
579 
580 #ifdef _KERNEL
581 #define	IFAFREE(ifa)					\
582 	do {						\
583 		IFA_LOCK(ifa);				\
584 		KASSERT((ifa)->ifa_refcnt > 0,		\
585 		    ("ifa %p !(ifa_refcnt > 0)", ifa));	\
586 		if (--(ifa)->ifa_refcnt == 0) {		\
587 			IFA_DESTROY(ifa);		\
588 			free(ifa, M_IFADDR);		\
589 		} else 					\
590 			IFA_UNLOCK(ifa);		\
591 	} while (0)
592 
593 #define IFAREF(ifa)					\
594 	do {						\
595 		IFA_LOCK(ifa);				\
596 		++(ifa)->ifa_refcnt;			\
597 		IFA_UNLOCK(ifa);			\
598 	} while (0)
599 
600 extern	struct mtx ifnet_lock;
601 #define	IFNET_LOCK_INIT() \
602     mtx_init(&ifnet_lock, "ifnet", NULL, MTX_DEF | MTX_RECURSE)
603 #define	IFNET_WLOCK()		mtx_lock(&ifnet_lock)
604 #define	IFNET_WUNLOCK()		mtx_unlock(&ifnet_lock)
605 #define	IFNET_RLOCK()		IFNET_WLOCK()
606 #define	IFNET_RUNLOCK()		IFNET_WUNLOCK()
607 
608 struct ifindex_entry {
609 	struct	ifnet *ife_ifnet;
610 	struct	ifaddr *ife_ifnet_addr;
611 	struct cdev *ife_dev;
612 };
613 
614 #define ifnet_byindex(idx)	ifindex_table[(idx)].ife_ifnet
615 /*
616  * Given the index, ifaddr_byindex() returns the one and only
617  * link-level ifaddr for the interface. You are not supposed to use
618  * it to traverse the list of addresses associated to the interface.
619  */
620 #define ifaddr_byindex(idx)	ifindex_table[(idx)].ife_ifnet_addr
621 #define ifdev_byindex(idx)	ifindex_table[(idx)].ife_dev
622 
623 extern	struct ifnethead ifnet;
624 extern	struct ifindex_entry *ifindex_table;
625 extern	int ifqmaxlen;
626 extern	struct ifnet *loif;	/* first loopback interface */
627 extern	int if_index;
628 
629 int	if_addmulti(struct ifnet *, struct sockaddr *, struct ifmultiaddr **);
630 int	if_allmulti(struct ifnet *, int);
631 void	if_attach(struct ifnet *);
632 int	if_delmulti(struct ifnet *, struct sockaddr *);
633 void	if_detach(struct ifnet *);
634 void	if_purgeaddrs(struct ifnet *);
635 void	if_down(struct ifnet *);
636 void	if_initname(struct ifnet *, const char *, int);
637 void	if_link_state_change(struct ifnet *, int);
638 int	if_printf(struct ifnet *, const char *, ...) __printflike(2, 3);
639 int	if_setlladdr(struct ifnet *, const u_char *, int);
640 void	if_up(struct ifnet *);
641 /*void	ifinit(void);*/ /* declared in systm.h for main() */
642 int	ifioctl(struct socket *, u_long, caddr_t, struct thread *);
643 int	ifpromisc(struct ifnet *, int);
644 struct	ifnet *ifunit(const char *);
645 
646 struct	ifaddr *ifa_ifwithaddr(struct sockaddr *);
647 struct	ifaddr *ifa_ifwithdstaddr(struct sockaddr *);
648 struct	ifaddr *ifa_ifwithnet(struct sockaddr *);
649 struct	ifaddr *ifa_ifwithroute(int, struct sockaddr *, struct sockaddr *);
650 struct	ifaddr *ifaof_ifpforaddr(struct sockaddr *, struct ifnet *);
651 
652 struct	ifmultiaddr *ifmaof_ifpforaddr(struct sockaddr *, struct ifnet *);
653 int	if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen);
654 
655 #define IF_LLADDR(ifp)							\
656     LLADDR((struct sockaddr_dl *) ifaddr_byindex((ifp)->if_index)->ifa_addr)
657 
658 #ifdef DEVICE_POLLING
659 enum poll_cmd {	POLL_ONLY, POLL_AND_CHECK_STATUS, POLL_DEREGISTER };
660 
661 typedef	void poll_handler_t(struct ifnet *ifp, enum poll_cmd cmd, int count);
662 int    ether_poll_register(poll_handler_t *h, struct ifnet *ifp);
663 int    ether_poll_deregister(struct ifnet *ifp);
664 #endif /* DEVICE_POLLING */
665 
666 #endif /* _KERNEL */
667 
668 #endif /* !_NET_IF_VAR_H_ */
669