xref: /dragonfly/sys/sys/mbuf.h (revision 03be034e)
1 /*
2  * Copyright (c) 2004 The DragonFly Project.  All rights reserved.
3  *
4  * Copyright (c) 1982, 1986, 1988, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  *
35  *	@(#)mbuf.h	8.5 (Berkeley) 2/19/95
36  * $FreeBSD: src/sys/sys/mbuf.h,v 1.44.2.17 2003/04/15 06:15:02 silby Exp $
37  * $DragonFly: src/sys/sys/mbuf.h,v 1.32 2005/07/15 17:54:48 eirikn Exp $
38  */
39 
40 #ifndef _SYS_MBUF_H_
41 #define	_SYS_MBUF_H_
42 
43 #include <sys/queue.h>
44 
45 /*
46  * Mbufs are of a single size, MSIZE (machine/param.h), which
47  * includes overhead.  An mbuf may add a single "mbuf cluster" of size
48  * MCLBYTES (also in machine/param.h), which has no additional overhead
49  * and is used instead of the internal data area; this is done when
50  * at least MINCLSIZE of data must be stored.
51  */
52 #define	MLEN		(MSIZE - sizeof(struct m_hdr))	/* normal data len */
53 #define	MHLEN		(MLEN - sizeof(struct pkthdr))	/* data len w/pkthdr */
54 #define	MINCLSIZE	(MHLEN + 1)	/* smallest amount to put in cluster */
55 #define	M_MAXCOMPRESS	(MHLEN / 2)	/* max amount to copy for compression */
56 
57 /*
58  * Macros for type conversion:
59  * mtod(m, t)	-- Convert mbuf pointer to data pointer of correct type.
60  * mtocl(x) -	convert pointer within cluster to cluster index #
61  * cltom(x) -	convert cluster # to ptr to beginning of cluster
62  */
63 #define	mtod(m, t)	((t)((m)->m_data))
64 
65 /*
66  * Header present at the beginning of every mbuf.
67  */
68 struct m_hdr {
69 	struct	mbuf *mh_next;		/* next buffer in chain */
70 	struct	mbuf *mh_nextpkt;	/* next chain in queue/record */
71 	caddr_t	mh_data;		/* location of data */
72 	int	mh_len;			/* amount of data in this mbuf */
73 	short	mh_type;		/* type of data in this mbuf */
74 	short	mh_flags;		/* flags; see below */
75 };
76 
77 /*
78  * Packet tag structure (see below for details).
79  */
80 struct m_tag {
81 	SLIST_ENTRY(m_tag)	m_tag_link;	/* List of packet tags */
82 	u_int16_t		m_tag_id;	/* Tag ID */
83 	u_int16_t		m_tag_len;	/* Length of data */
84 	u_int32_t		m_tag_cookie;	/* ABI/Module ID */
85 };
86 
87 SLIST_HEAD(packet_tags, m_tag);
88 
89 /*
90  * Record/packet header in first mbuf of chain; valid only if M_PKTHDR is set.
91  *
92  * Be careful: The fields have been carefully ordered to avoid hidden padding.
93  *             Keep this in mind, when adding or removing fields!
94  */
95 struct pkthdr {
96 	struct	ifnet *rcvif;		/* rcv interface */
97 	int	len;			/* total packet length */
98 	struct packet_tags tags;	/* list of packet tags */
99 
100 	/* variables for ip and tcp reassembly */
101 	void	*header;		/* pointer to packet header */
102 
103 	/* variables for hardware checksum */
104 	int	csum_flags;		/* flags regarding checksum */
105 	int	csum_data;		/* data field used by csum routines */
106 
107 	/* firewall flags */
108 	uint32_t fw_flags;		/* flags for PF */
109 
110 	/* variables for PF processing */
111 	uint16_t pf_tag;		/* PF tag id */
112 	uint8_t	pf_routed;		/* PF routing counter */
113 
114 	/* variables for ALTQ processing */
115 	uint8_t	ecn_af;			/* address family for ECN */
116 	uint32_t altq_qid;		/* queue id */
117 };
118 
119 /*
120  * Description of external storage mapped into mbuf; valid only if M_EXT is set.
121  */
122 struct m_ext {
123 	caddr_t	ext_buf;		/* start of buffer */
124 	void	(*ext_free)(void *);
125 	u_int	ext_size;		/* size of buffer, for ext_free */
126 	void	(*ext_ref)(void *);
127 	void	*ext_arg;
128 };
129 
130 /*
131  * The core of the mbuf object along with some shortcut defines for
132  * practical purposes.
133  */
134 struct mbuf {
135 	struct	m_hdr m_hdr;
136 	union {
137 		struct {
138 			struct	pkthdr MH_pkthdr;	/* M_PKTHDR set */
139 			union {
140 				struct	m_ext MH_ext;	/* M_EXT set */
141 				char	MH_databuf[MHLEN];
142 			} MH_dat;
143 		} MH;
144 		char	M_databuf[MLEN];		/* !M_PKTHDR, !M_EXT */
145 	} M_dat;
146 };
147 #define	m_next		m_hdr.mh_next
148 #define	m_len		m_hdr.mh_len
149 #define	m_data		m_hdr.mh_data
150 #define	m_type		m_hdr.mh_type
151 #define	m_flags		m_hdr.mh_flags
152 #define	m_nextpkt	m_hdr.mh_nextpkt
153 #define	m_pkthdr	M_dat.MH.MH_pkthdr
154 #define	m_ext		M_dat.MH.MH_dat.MH_ext
155 #define	m_pktdat	M_dat.MH.MH_dat.MH_databuf
156 #define	m_dat		M_dat.M_databuf
157 
158 /*
159  * Code that uses m_act should be converted to use m_nextpkt
160  * instead; m_act is historical and deprecated.
161  */
162 #define m_act   	m_nextpkt
163 
164 /*
165  * mbuf flags.
166  */
167 #define	M_EXT		0x0001	/* has associated external storage */
168 #define	M_PKTHDR	0x0002	/* start of record */
169 #define	M_EOR		0x0004	/* end of record */
170 #define	M_PROTO1	0x0008	/* protocol-specific */
171 #define	M_PROTO2	0x0010	/* protocol-specific */
172 #define	M_PROTO3	0x0020	/* protocol-specific */
173 #define	M_PROTO4	0x0040	/* protocol-specific */
174 #define	M_PROTO5	0x0080	/* protocol-specific */
175 
176 /*
177  * mbuf pkthdr flags (also stored in m_flags).
178  */
179 #define	M_BCAST		0x0100	/* send/received as link-level broadcast */
180 #define	M_MCAST		0x0200	/* send/received as link-level multicast */
181 #define	M_FRAG		0x0400	/* packet is a fragment of a larger packet */
182 #define	M_FIRSTFRAG	0x0800	/* packet is first fragment */
183 #define	M_LASTFRAG	0x1000	/* packet is last fragment */
184 #define	M_CLCACHE	0x2000	/* mbuf allocated from the cluster cache */
185 #define M_EXT_CLUSTER	0x4000	/* standard cluster else special */
186 #define	M_PHCACHE	0x8000	/* mbuf allocated from the pkt header cache */
187 #define M_NOTIFICATION	0x10000	/* notification event */
188 
189 /*
190  * Flags copied when copying m_pkthdr.
191  */
192 #define	M_COPYFLAGS	(M_PKTHDR|M_EOR|M_PROTO1|M_PROTO1|M_PROTO2|M_PROTO3 | \
193 			    M_PROTO4|M_PROTO5|M_BCAST|M_MCAST|M_FRAG | \
194 			    M_FIRSTFRAG|M_LASTFRAG)
195 
196 /*
197  * Flags indicating hw checksum support and sw checksum requirements.
198  */
199 #define	CSUM_IP			0x0001		/* will csum IP */
200 #define	CSUM_TCP		0x0002		/* will csum TCP */
201 #define	CSUM_UDP		0x0004		/* will csum UDP */
202 #define	CSUM_IP_FRAGS		0x0008		/* will csum IP fragments */
203 #define	CSUM_FRAGMENT		0x0010		/* will do IP fragmentation */
204 
205 #define	CSUM_IP_CHECKED		0x0100		/* did csum IP */
206 #define	CSUM_IP_VALID		0x0200		/*   ... the csum is valid */
207 #define	CSUM_DATA_VALID		0x0400		/* csum_data field is valid */
208 #define	CSUM_PSEUDO_HDR		0x0800		/* csum_data has pseudo hdr */
209 
210 #define	CSUM_DELAY_DATA		(CSUM_TCP | CSUM_UDP)
211 #define	CSUM_DELAY_IP		(CSUM_IP)	/* XXX add ipv6 here too? */
212 
213 /*
214  * Flags indicating PF processing status
215  */
216 #define	PF_MBUF_GENERATED	0x00000001
217 #define	PF_MBUF_TAGGED		0x00000002	/* pf_tag field is valid */
218 #define	PF_MBUF_ROUTED		0x00000004	/* pf_routed field is valid */
219 #define	PF_MBUF_TRANSLATE_LOCALHOST					\
220 				0x00000008
221 #define	PF_MBUF_FRAGCACHE	0x00000010
222 #define	ALTQ_MBUF_TAGGED	0x00000020	/* altq_qid is valid */
223 
224 /*
225  * mbuf types.
226  */
227 #define	MT_FREE		0	/* should be on free list */
228 #define	MT_DATA		1	/* dynamic (data) allocation */
229 #define	MT_HEADER	2	/* packet header */
230 #define	MT_SONAME	3	/* socket name */
231 #define	MT_TAG		4	/* volatile metadata associated to pkts */
232 #define	MT_CONTROL	5	/* extra-data protocol message */
233 #define	MT_OOBDATA	6	/* expedited data  */
234 #define	MT_NTYPES	7	/* number of mbuf types for mbtypes[] */
235 
236 /*
237  * General mbuf allocator statistics structure.
238  */
239 struct mbstat {
240 	u_long	m_mbufs;	/* mbufs obtained from page pool */
241 	u_long	m_clusters;	/* clusters obtained from page pool */
242 	u_long	m_spare;	/* spare field */
243 	u_long	m_clfree;	/* free clusters */
244 	u_long	m_drops;	/* times failed to find space */
245 	u_long	m_wait;		/* times waited for space */
246 	u_long	m_drain;	/* times drained protocols for space */
247 	u_long	m_mcfail;	/* times m_copym failed */
248 	u_long	m_mpfail;	/* times m_pullup failed */
249 	u_long	m_msize;	/* length of an mbuf */
250 	u_long	m_mclbytes;	/* length of an mbuf cluster */
251 	u_long	m_minclsize;	/* min length of data to allocate a cluster */
252 	u_long	m_mlen;		/* length of data in an mbuf */
253 	u_long	m_mhlen;	/* length of data in a header mbuf */
254 };
255 
256 /*
257  * Flags specifying how an allocation should be made.
258  */
259 
260 #define	MB_DONTWAIT	0x4
261 #define	MB_TRYWAIT	0x8
262 #define	MB_WAIT		MB_TRYWAIT
263 
264 /*
265  * Mbuf to Malloc Flag Conversion.
266  */
267 #define	MBTOM(how)	((how) & MB_TRYWAIT ? M_WAITOK : M_NOWAIT)
268 
269 /*
270  * These are identifying numbers passed to the m_mballoc_wait function,
271  * allowing us to determine whether the call came from an MGETHDR or
272  * an MGET.
273  */
274 #define	MGETHDR_C      1
275 #define	MGET_C         2
276 
277 /*
278  * mbuf allocation/deallocation macros (YYY deprecated, too big):
279  *
280  *	MGET(struct mbuf *m, int how, int type)
281  * allocates an mbuf and initializes it to contain internal data.
282  *
283  *	MGETHDR(struct mbuf *m, int how, int type)
284  * allocates an mbuf and initializes it to contain a packet header
285  * and internal data.
286  */
287 #define	MGET(m, how, type) do {						\
288 	(m) = m_get((how), (type));					\
289 } while (0)
290 
291 #define	MGETHDR(m, how, type) do {					\
292 	(m) = m_gethdr((how), (type));					\
293 } while (0)
294 
295 /*
296  * MCLGET adds such clusters to a normal mbuf.  The flag M_EXT is set upon
297  * success.
298  * Deprecated.  Use m_getcl() or m_getl() instead.
299  */
300 #define	MCLGET(m, how) do {						\
301 	m_mclget((m), (how));						\
302 } while (0)
303 
304 /*
305  * NB: M_COPY_PKTHDR is deprecated; use either M_MOVE_PKTHDR
306  *     or m_dup_pkthdr.
307  */
308 /*
309  * Move mbuf pkthdr from "from" to "to".
310  * from should have M_PKTHDR set, and to must be empty.
311  * from no longer has a pkthdr after this operation.
312  */
313 #define	M_MOVE_PKTHDR(_to, _from)	m_move_pkthdr((_to), (_from))
314 
315 /*
316  * Set the m_data pointer of a newly-allocated mbuf (m_get/MGET) to place
317  * an object of the specified size at the end of the mbuf, longword aligned.
318  */
319 #define	M_ALIGN(m, len) do {						\
320 	(m)->m_data += (MLEN - (len)) & ~(sizeof(long) - 1);		\
321 } while (0)
322 
323 /*
324  * As above, for mbufs allocated with m_gethdr/MGETHDR
325  * or initialized by M_COPY_PKTHDR.
326  */
327 #define	MH_ALIGN(m, len) do {						\
328 	(m)->m_data += (MHLEN - (len)) & ~(sizeof(long) - 1);		\
329 } while (0)
330 
331 /*
332  * Check if we can write to an mbuf.
333  */
334 #define M_EXT_WRITABLE(m)	(m_sharecount(m) == 1)
335 #define M_WRITABLE(m)		(!((m)->m_flags & M_EXT) || M_EXT_WRITABLE(m))
336 
337 /*
338  * Check if the supplied mbuf has a packet header, or else panic.
339  */
340 #define	M_ASSERTPKTHDR(m)						\
341 	KASSERT(m != NULL && m->m_flags & M_PKTHDR,			\
342 		("%s: invalid mbuf or no mbuf packet header!", __func__))
343 
344 /*
345  * Compute the amount of space available before the current start of data.
346  * The M_EXT_WRITABLE() is a temporary, conservative safety measure: the burden
347  * of checking writability of the mbuf data area rests solely with the caller.
348  */
349 #define	M_LEADINGSPACE(m)						\
350 	((m)->m_flags & M_EXT ?						\
351 	    (M_EXT_WRITABLE(m) ? (m)->m_data - (m)->m_ext.ext_buf : 0):	\
352 	    (m)->m_flags & M_PKTHDR ? (m)->m_data - (m)->m_pktdat :	\
353 	    (m)->m_data - (m)->m_dat)
354 
355 /*
356  * Compute the amount of space available after the end of data in an mbuf.
357  * The M_WRITABLE() is a temporary, conservative safety measure: the burden
358  * of checking writability of the mbuf data area rests solely with the caller.
359  */
360 #define	M_TRAILINGSPACE(m)						\
361 	((m)->m_flags & M_EXT ?						\
362 	    (M_WRITABLE(m) ? (m)->m_ext.ext_buf + (m)->m_ext.ext_size	\
363 		- ((m)->m_data + (m)->m_len) : 0) :			\
364 	    &(m)->m_dat[MLEN] - ((m)->m_data + (m)->m_len))
365 
366 /*
367  * Arrange to prepend space of size plen to mbuf m.
368  * If a new mbuf must be allocated, how specifies whether to wait.
369  * If how is MB_DONTWAIT and allocation fails, the original mbuf chain
370  * is freed and m is set to NULL.
371  */
372 #define	M_PREPEND(m, plen, how) do {					\
373 	struct mbuf **_mmp = &(m);					\
374 	struct mbuf *_mm = *_mmp;					\
375 	int _mplen = (plen);						\
376 	int __mhow = (how);						\
377 									\
378 	if (M_LEADINGSPACE(_mm) >= _mplen) {				\
379 		_mm->m_data -= _mplen;					\
380 		_mm->m_len += _mplen;					\
381 	} else								\
382 		_mm = m_prepend(_mm, _mplen, __mhow);			\
383 	if (_mm != NULL && _mm->m_flags & M_PKTHDR)			\
384 		_mm->m_pkthdr.len += _mplen;				\
385 	*_mmp = _mm;							\
386 } while (0)
387 
388 /* Length to m_copy to copy all. */
389 #define	M_COPYALL	1000000000
390 
391 /* Compatibility with 4.3 */
392 #define	m_copy(m, o, l)	m_copym((m), (o), (l), MB_DONTWAIT)
393 
394 #ifdef _KERNEL
395 extern	u_int		 m_clalloc_wid;	/* mbuf cluster wait count */
396 extern	u_int		 m_mballoc_wid;	/* mbuf wait count */
397 extern	int		 max_linkhdr;	/* largest link-level header */
398 extern	int		 max_protohdr;	/* largest protocol header */
399 extern	int		 max_hdr;	/* largest link+protocol header */
400 extern	int		 max_datalen;	/* MHLEN - max_hdr */
401 extern	struct mbstat	 mbstat;
402 extern	int		 mbuf_wait;	/* mbuf sleep time */
403 extern	int		 nmbclusters;
404 extern	int		 nmbufs;
405 
406 struct uio;
407 
408 void		 m_adj(struct mbuf *, int);
409 void		 m_cat(struct mbuf *, struct mbuf *);
410 u_int		 m_countm(struct mbuf *m, struct mbuf **lastm, u_int *mbcnt);
411 void		 m_copyback(struct mbuf *, int, int, caddr_t);
412 void		 m_copydata(const struct mbuf *, int, int, caddr_t);
413 struct	mbuf	*m_copym(const struct mbuf *, int, int, int);
414 struct	mbuf	*m_copypacket(struct mbuf *, int);
415 struct	mbuf	*m_defrag(struct mbuf *, int);
416 struct	mbuf	*m_defrag_nofree(struct mbuf *, int);
417 struct	mbuf	*m_devget(char *, int, int, struct ifnet *,
418 		  void (*copy)(volatile const void *, volatile void *, size_t));
419 struct	mbuf	*m_dup(struct mbuf *, int);
420 int		 m_dup_pkthdr(struct mbuf *, const struct mbuf *, int);
421 struct	mbuf	*m_free(struct mbuf *);
422 void		 m_freem(struct mbuf *);
423 struct	mbuf	*m_get(int, int);
424 struct	mbuf	*m_getc(int len, int how, int type);
425 struct	mbuf	*m_getcl(int how, short type, int flags);
426 struct	mbuf	*m_getclr(int, int);
427 struct	mbuf	*m_gethdr(int, int);
428 struct	mbuf	*m_getm(struct mbuf *, int, int, int);
429 struct	mbuf	*m_last(struct mbuf *m);
430 u_int		 m_lengthm(struct mbuf *m, struct mbuf **lastm);
431 void		 m_move_pkthdr(struct mbuf *, struct mbuf *);
432 struct	mbuf	*m_prepend(struct mbuf *, int, int);
433 void		 m_print(const struct mbuf *m);
434 struct	mbuf	*m_pulldown(struct mbuf *, int, int, int *);
435 struct	mbuf	*m_pullup(struct mbuf *, int);
436 struct	mbuf	*m_split(struct mbuf *, int, int);
437 struct	mbuf 	*m_uiomove(struct uio *);
438 void		m_mclget(struct mbuf *m, int how);
439 int		m_sharecount(struct mbuf *m);
440 void		m_chtype(struct mbuf *m, int type);
441 
442 /*
443  * Allocate the right type of mbuf for the desired total length.
444  */
445 static __inline struct mbuf *
446 m_getl(int len, int how, int type, int flags, int *psize)
447 {
448 	struct mbuf *m;
449 	int size;
450 
451 	if (len >= MINCLSIZE) {
452 		m = m_getcl(how, type, flags);
453 		size = MCLBYTES;
454 	} else if (flags & M_PKTHDR) {
455 		m = m_gethdr(how, type);
456 		size = MHLEN;
457 	} else {
458 		m = m_get(how, type);
459 		size = MLEN;
460 	}
461 	if (psize != NULL)
462 		*psize = size;
463 	return (m);
464 }
465 
466 /*
467  * Packets may have annotations attached by affixing a list
468  * of "packet tags" to the pkthdr structure.  Packet tags are
469  * dynamically allocated semi-opaque data structures that have
470  * a fixed header (struct m_tag) that specifies the size of the
471  * memory block and a <cookie,type> pair that identifies it.
472  * The cookie is a 32-bit unique unsigned value used to identify
473  * a module or ABI.  By convention this value is chose as the
474  * date+time that the module is created, expressed as the number of
475  * seconds since the epoch (e.g. using date -u +'%s').  The type value
476  * is an ABI/module-specific value that identifies a particular annotation
477  * and is private to the module.  For compatibility with systems
478  * like openbsd that define packet tags w/o an ABI/module cookie,
479  * the value PACKET_ABI_COMPAT is used to implement m_tag_get and
480  * m_tag_find compatibility shim functions and several tag types are
481  * defined below.  Users that do not require compatibility should use
482  * a private cookie value so that packet tag-related definitions
483  * can be maintained privately.
484  *
485  * Note that the packet tag returned by m_tag_allocate has the default
486  * memory alignment implemented by malloc.  To reference private data
487  * one can use a construct like:
488  *
489  *	struct m_tag *mtag = m_tag_allocate(...);
490  *	struct foo *p = (struct foo *)(mtag+1);
491  *
492  * if the alignment of struct m_tag is sufficient for referencing members
493  * of struct foo.  Otherwise it is necessary to embed struct m_tag within
494  * the private data structure to insure proper alignment; e.g.
495  *
496  *	struct foo {
497  *		struct m_tag	tag;
498  *		...
499  *	};
500  *	struct foo *p = (struct foo *) m_tag_allocate(...);
501  *	struct m_tag *mtag = &p->tag;
502  */
503 
504 #define	PACKET_TAG_NONE				0  /* Nadda */
505 
506 /* Packet tag for use with PACKET_ABI_COMPAT */
507 #define	PACKET_TAG_IPSEC_IN_DONE		1  /* IPsec applied, in */
508 /* struct tdb_indent */
509 #define	PACKET_TAG_IPSEC_OUT_DONE		2  /* IPsec applied, out */
510 /* struct tdb_indent */
511 #define	PACKET_TAG_IPSEC_IN_CRYPTO_DONE		3  /* NIC IPsec crypto done */
512 /* struct tdb_indent, never added */
513 #define	PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED	4  /* NIC IPsec crypto req'ed */
514 /* struct tdb_indent, never added */
515 #define	PACKET_TAG_IPSEC_PENDING_TDB		5  /* Reminder to do IPsec */
516 /* struct tdb_indent, never added */
517 #define	PACKET_TAG_ENCAP			6 /* Encap.  processing */
518 /* struct ifnet *, the GIF interface */
519 #define	PACKET_TAG_IPSEC_HISTORY		7 /* IPSEC history */
520 /* struct ipsec_history */
521 #define	PACKET_TAG_IPV6_INPUT			8 /* IPV6 input processing */
522 /* struct ip6aux */
523 #define	PACKET_TAG_IPFW_DIVERT			9 /* divert info */
524 /* uint16_t */
525 
526 /*
527  * As a temporary and low impact solution to replace the even uglier
528  * approach used so far in some parts of the network stack (which relies
529  * on global variables), packet tag-like annotations are stored in MT_TAG
530  * mbufs (or lookalikes) prepended to the actual mbuf chain.
531  *
532  *	m_type	= MT_TAG
533  *	m_flags = m_tag_id
534  *	m_next	= next buffer in chain.
535  *
536  * BE VERY CAREFUL not to pass these blocks to the mbuf handling routines.
537  */
538 #define	_m_tag_id	m_hdr.mh_flags
539 
540 /* Packet tags used in the FreeBSD network stack */
541 #define	PACKET_TAG_DUMMYNET			15 /* dummynet info */
542 /* struct dn_pkt as fake mbuf */
543 #define	PACKET_TAG_IPFORWARD			18 /* ipforward info */
544 /* struct sockaddr_in * as m_data */
545 
546 /* Packet tag routines */
547 struct	m_tag 	*m_tag_alloc(u_int32_t, int, int, int);
548 void		 m_tag_free(struct m_tag *);
549 void		 m_tag_prepend(struct mbuf *, struct m_tag *);
550 void		 m_tag_unlink(struct mbuf *, struct m_tag *);
551 void		 m_tag_delete(struct mbuf *, struct m_tag *);
552 void		 m_tag_delete_chain(struct mbuf *);
553 struct	m_tag	*m_tag_locate(struct mbuf *, u_int32_t, int, struct m_tag *);
554 struct	m_tag	*m_tag_copy(struct m_tag *, int);
555 int		 m_tag_copy_chain(struct mbuf *, const struct mbuf *, int);
556 void		 m_tag_init(struct mbuf *);
557 struct	m_tag	*m_tag_first(struct mbuf *);
558 struct	m_tag	*m_tag_next(struct mbuf *, struct m_tag *);
559 
560 /* these are for openbsd compatibility */
561 #define	MTAG_ABI_COMPAT		0		/* compatibility ABI */
562 
563 static __inline void *
564 m_tag_data(struct m_tag *tag)
565 {
566 	return ((void *)(tag + 1));
567 }
568 
569 static __inline struct m_tag *
570 m_tag_get(int type, int length, int wait)
571 {
572 	return m_tag_alloc(MTAG_ABI_COMPAT, type, length, wait);
573 }
574 
575 static __inline struct m_tag *
576 m_tag_find(struct mbuf *m, int type, struct m_tag *start)
577 {
578 	return m_tag_locate(m, MTAG_ABI_COMPAT, type, start);
579 }
580 #endif /* _KERNEL */
581 
582 #endif /* !_SYS_MBUF_H_ */
583