sys/sys/mbuf.h

   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 1.37 2006/09/29 05:37:03 hsu Exp $
  38  */
  39
  40 #ifndef _SYS_MBUF_H_
  41 #define _SYS_MBUF_H_
  42
  43 #if defined(_KERNEL) || defined(_KERNEL_STRUCTURES)
  44
  45 #ifndef _SYS_TYPES_H_
  46 #include <sys/types.h>
  47 #endif
  48 #ifndef _SYS_PARAM_H_
  49 #include <sys/param.h>
  50 #endif
  51 #ifndef _SYS_QUEUE_H_
  52 #include <sys/queue.h>
  53 #endif
  54 #ifndef _NET_NETISR_H_
  55 #include <net/netisr.h>
  56 #endif
  57
  58 /*
  59  * Mbufs are of a single size, MSIZE (machine/param.h), which
  60  * includes overhead.  An mbuf may add a single "mbuf cluster" of size
  61  * MCLBYTES (also in machine/param.h), which has no additional overhead
  62  * and is used instead of the internal data area; this is done when
  63  * at least MINCLSIZE of data must be stored.
  64  */
  65 #define MLEN            (MSIZE - sizeof(struct m_hdr))  /* normal data len */
  66 #define MHLEN           (MLEN - sizeof(struct pkthdr))  /* data len w/pkthdr */
  67 #define MINCLSIZE       (MHLEN + 1)     /* smallest amount to put in cluster */
  68 #define M_MAXCOMPRESS   (MHLEN / 2)     /* max amount to copy for compression */
  69
  70 /*
  71  * Macros for type conversion:
  72  * mtod(m, t)   -- Convert mbuf pointer to data pointer of correct type.
  73  * mtocl(x) -   convert pointer within cluster to cluster index #
  74  * cltom(x) -   convert cluster # to ptr to beginning of cluster
  75  */
  76 #define mtod(m, t)      ((t)((m)->m_data))
  77
  78 /*
  79  * Header present at the beginning of every mbuf.
  80  */
  81 struct m_hdr {
  82         struct  mbuf *mh_next;          /* next buffer in chain */
  83         struct  mbuf *mh_nextpkt;       /* next chain in queue/record */
  84         caddr_t mh_data;                /* location of data */
  85         int     mh_len;                 /* amount of data in this mbuf */
  86         short   mh_type;                /* type of data in this mbuf */
  87         short   mh_flags;               /* flags; see below */
  88         struct netmsg_packet mh_netmsg; /* hardware->proto stack msg */
  89 };
  90
  91 /*
  92  * Packet tag structure (see below for details).
  93  */
  94 struct m_tag {
  95         SLIST_ENTRY(m_tag)      m_tag_link;     /* List of packet tags */
  96         u_int16_t               m_tag_id;       /* Tag ID */
  97         u_int16_t               m_tag_len;      /* Length of data */
  98         u_int32_t               m_tag_cookie;   /* ABI/Module ID */
  99 };
 100
 101 SLIST_HEAD(packet_tags, m_tag);
 102
 103 /*
 104  * Record/packet header in first mbuf of chain; valid only if M_PKTHDR is set.
 105  *
 106  * Be careful: The fields have been carefully ordered to avoid hidden padding.
 107  *             Keep this in mind, when adding or removing fields!
 108  */
 109 struct pkthdr {
 110         struct  ifnet *rcvif;           /* rcv interface */
 111         int     len;                    /* total packet length */
 112         struct packet_tags tags;        /* list of packet tags */
 113
 114         /* variables for ip and tcp reassembly */
 115         void    *header;                /* pointer to packet header */
 116
 117         /* variables for hardware checksum */
 118         int     csum_flags;             /* flags regarding checksum */
 119         int     csum_data;              /* data field used by csum routines */
 120
 121         /* firewall flags */
 122         uint32_t fw_flags;              /* flags for PF */
 123
 124         /* variables for PF processing */
 125         uint16_t pf_tag;                /* PF tag id */
 126         uint8_t pf_routed;              /* PF routing counter */
 127
 128         /* variables for ALTQ processing */
 129         uint8_t ecn_af;                 /* address family for ECN */
 130         uint32_t altq_qid;              /* queue id */
 131 };
 132
 133 /*
 134  * Description of external storage mapped into mbuf; valid only if M_EXT is set.
 135  */
 136 struct m_ext {
 137         caddr_t ext_buf;                /* start of buffer */
 138         void    (*ext_free)(void *);
 139         u_int   ext_size;               /* size of buffer, for ext_free */
 140         void    (*ext_ref)(void *);
 141         void    *ext_arg;
 142 };
 143
 144 /*
 145  * The core of the mbuf object along with some shortcut defines for
 146  * practical purposes.
 147  */
 148 struct mbuf {
 149         struct  m_hdr m_hdr;
 150         union {
 151                 struct {
 152                         struct  pkthdr MH_pkthdr;       /* M_PKTHDR set */
 153                         union {
 154                                 struct  m_ext MH_ext;   /* M_EXT set */
 155                                 char    MH_databuf[MHLEN];
 156                         } MH_dat;
 157                 } MH;
 158                 char    M_databuf[MLEN];                /* !M_PKTHDR, !M_EXT */
 159         } M_dat;
 160 };
 161 #define m_next          m_hdr.mh_next
 162 #define m_len           m_hdr.mh_len
 163 #define m_data          m_hdr.mh_data
 164 #define m_type          m_hdr.mh_type
 165 #define m_flags         m_hdr.mh_flags
 166 #define m_nextpkt       m_hdr.mh_nextpkt
 167 #define m_pkthdr        M_dat.MH.MH_pkthdr
 168 #define m_ext           M_dat.MH.MH_dat.MH_ext
 169 #define m_pktdat        M_dat.MH.MH_dat.MH_databuf
 170 #define m_dat           M_dat.M_databuf
 171
 172 /*
 173  * Code that uses m_act should be converted to use m_nextpkt
 174  * instead; m_act is historical and deprecated.
 175  */
 176 #define m_act           m_nextpkt
 177
 178 /*
 179  * mbuf flags.
 180  */
 181 #define M_EXT           0x0001  /* has associated external storage */
 182 #define M_PKTHDR        0x0002  /* start of record */
 183 #define M_EOR           0x0004  /* end of record */
 184 #define M_PROTO1        0x0008  /* protocol-specific */
 185 #define M_PROTO2        0x0010  /* protocol-specific */
 186 #define M_PROTO3        0x0020  /* protocol-specific */
 187 #define M_PROTO4        0x0040  /* protocol-specific */
 188 #define M_PROTO5        0x0080  /* protocol-specific */
 189
 190 /*
 191  * mbuf pkthdr flags (also stored in m_flags).
 192  */
 193 #define M_BCAST         0x0100  /* send/received as link-level broadcast */
 194 #define M_MCAST         0x0200  /* send/received as link-level multicast */
 195 #define M_FRAG          0x0400  /* packet is a fragment of a larger packet */
 196 #define M_FIRSTFRAG     0x0800  /* packet is first fragment */
 197 #define M_LASTFRAG      0x1000  /* packet is last fragment */
 198 #define M_CLCACHE       0x2000  /* mbuf allocated from the cluster cache */
 199 #define M_EXT_CLUSTER   0x4000  /* standard cluster else special */
 200 #define M_PHCACHE       0x8000  /* mbuf allocated from the pkt header cache */
 201 #define M_NOTIFICATION  0x10000 /* notification event */
 202
 203 /*
 204  * Flags copied when copying m_pkthdr.
 205  */
 206 #define M_COPYFLAGS     (M_PKTHDR|M_EOR|M_PROTO1|M_PROTO1|M_PROTO2|M_PROTO3 | \
 207                             M_PROTO4|M_PROTO5|M_BCAST|M_MCAST|M_FRAG | \
 208                             M_FIRSTFRAG|M_LASTFRAG)
 209
 210 /*
 211  * Flags indicating hw checksum support and sw checksum requirements.
 212  */
 213 #define CSUM_IP                 0x0001          /* will csum IP */
 214 #define CSUM_TCP                0x0002          /* will csum TCP */
 215 #define CSUM_UDP                0x0004          /* will csum UDP */
 216 #define CSUM_IP_FRAGS           0x0008          /* will csum IP fragments */
 217 #define CSUM_FRAGMENT           0x0010          /* will do IP fragmentation */
 218
 219 #define CSUM_IP_CHECKED         0x0100          /* did csum IP */
 220 #define CSUM_IP_VALID           0x0200          /*   ... the csum is valid */
 221 #define CSUM_DATA_VALID         0x0400          /* csum_data field is valid */
 222 #define CSUM_PSEUDO_HDR         0x0800          /* csum_data has pseudo hdr */
 223
 224 #define CSUM_DELAY_DATA         (CSUM_TCP | CSUM_UDP)
 225 #define CSUM_DELAY_IP           (CSUM_IP)       /* XXX add ipv6 here too? */
 226
 227 /*
 228  * Flags indicating PF processing status
 229  */
 230 #define PF_MBUF_GENERATED       0x00000001
 231 #define PF_MBUF_TAGGED          0x00000002      /* pf_tag field is valid */
 232 #define PF_MBUF_ROUTED          0x00000004      /* pf_routed field is valid */
 233 #define PF_MBUF_TRANSLATE_LOCALHOST                                     \
 234                                 0x00000008
 235 #define PF_MBUF_FRAGCACHE       0x00000010
 236 #define ALTQ_MBUF_TAGGED        0x00000020      /* altq_qid is valid */
 237 #define IPFW_MBUF_SKIP_FIREWALL 0x00000040
 238
 239 /*
 240  * mbuf types.
 241  */
 242 #define MT_FREE         0       /* should be on free list */
 243 #define MT_DATA         1       /* dynamic (data) allocation */
 244 #define MT_HEADER       2       /* packet header */
 245 #define MT_SONAME       3       /* socket name */
 246 #define MT_TAG          4       /* volatile metadata associated to pkts */
 247 #define MT_CONTROL      5       /* extra-data protocol message */
 248 #define MT_OOBDATA      6       /* expedited data  */
 249 #define MT_NTYPES       7       /* number of mbuf types for mbtypes[] */
 250
 251 /*
 252  * General mbuf allocator statistics structure.
 253  */
 254 struct mbstat {
 255         u_long  m_mbufs;        /* mbufs obtained from page pool */
 256         u_long  m_clusters;     /* clusters obtained from page pool */
 257         u_long  m_spare;        /* spare field */
 258         u_long  m_clfree;       /* free clusters */
 259         u_long  m_drops;        /* times failed to find space */
 260         u_long  m_wait;         /* times waited for space */
 261         u_long  m_drain;        /* times drained protocols for space */
 262         u_long  m_mcfail;       /* times m_copym failed */
 263         u_long  m_mpfail;       /* times m_pullup failed */
 264         u_long  m_msize;        /* length of an mbuf */
 265         u_long  m_mclbytes;     /* length of an mbuf cluster */
 266         u_long  m_minclsize;    /* min length of data to allocate a cluster */
 267         u_long  m_mlen;         /* length of data in an mbuf */
 268         u_long  m_mhlen;        /* length of data in a header mbuf */
 269 };
 270
 271 /*
 272  * Flags specifying how an allocation should be made.
 273  */
 274
 275 #define MB_DONTWAIT     0x4
 276 #define MB_TRYWAIT      0x8
 277 #define MB_WAIT         MB_TRYWAIT
 278
 279 /*
 280  * Mbuf to Malloc Flag Conversion.
 281  */
 282 #define MBTOM(how)      ((how) & MB_TRYWAIT ? M_WAITOK : M_NOWAIT)
 283
 284 /*
 285  * These are identifying numbers passed to the m_mballoc_wait function,
 286  * allowing us to determine whether the call came from an MGETHDR or
 287  * an MGET.
 288  */
 289 #define MGETHDR_C      1
 290 #define MGET_C         2
 291
 292 /*
 293  * mbuf allocation/deallocation macros (YYY deprecated, too big):
 294  *
 295  *      MGET(struct mbuf *m, int how, int type)
 296  * allocates an mbuf and initializes it to contain internal data.
 297  *
 298  *      MGETHDR(struct mbuf *m, int how, int type)
 299  * allocates an mbuf and initializes it to contain a packet header
 300  * and internal data.
 301  */
 302 #define MGET(m, how, type) do {                                         \
 303         (m) = m_get((how), (type));                                     \
 304 } while (0)
 305
 306 #define MGETHDR(m, how, type) do {                                      \
 307         (m) = m_gethdr((how), (type));                                  \
 308 } while (0)
 309
 310 /*
 311  * MCLGET adds such clusters to a normal mbuf.  The flag M_EXT is set upon
 312  * success.
 313  * Deprecated.  Use m_getcl() or m_getl() instead.
 314  */
 315 #define MCLGET(m, how) do {                                             \
 316         m_mclget((m), (how));                                           \
 317 } while (0)
 318
 319 /*
 320  * NB: M_COPY_PKTHDR is deprecated; use either M_MOVE_PKTHDR
 321  *     or m_dup_pkthdr.
 322  */
 323 /*
 324  * Move mbuf pkthdr from "from" to "to".
 325  * from should have M_PKTHDR set, and to must be empty.
 326  * from no longer has a pkthdr after this operation.
 327  */
 328 #define M_MOVE_PKTHDR(_to, _from)       m_move_pkthdr((_to), (_from))
 329
 330 /*
 331  * Set the m_data pointer of a newly-allocated mbuf (m_get/MGET) to place
 332  * an object of the specified size at the end of the mbuf, longword aligned.
 333  */
 334 #define M_ALIGN(m, len) do {                                            \
 335         (m)->m_data += (MLEN - (len)) & ~(sizeof(long) - 1);            \
 336 } while (0)
 337
 338 /*
 339  * As above, for mbufs allocated with m_gethdr/MGETHDR
 340  * or initialized by M_COPY_PKTHDR.
 341  */
 342 #define MH_ALIGN(m, len) do {                                           \
 343         (m)->m_data += (MHLEN - (len)) & ~(sizeof(long) - 1);           \
 344 } while (0)
 345
 346 /*
 347  * Check if we can write to an mbuf.
 348  */
 349 #define M_EXT_WRITABLE(m)       (m_sharecount(m) == 1)
 350 #define M_WRITABLE(m)           (!((m)->m_flags & M_EXT) || M_EXT_WRITABLE(m))
 351
 352 /*
 353  * Check if the supplied mbuf has a packet header, or else panic.
 354  */
 355 #define M_ASSERTPKTHDR(m)                                               \
 356         KASSERT(m != NULL && m->m_flags & M_PKTHDR,                     \
 357                 ("%s: invalid mbuf or no mbuf packet header!", __func__))
 358
 359 /*
 360  * Compute the amount of space available before the current start of data.
 361  * The M_EXT_WRITABLE() is a temporary, conservative safety measure: the burden
 362  * of checking writability of the mbuf data area rests solely with the caller.
 363  */
 364 #define M_LEADINGSPACE(m)                                               \
 365         ((m)->m_flags & M_EXT ?                                         \
 366             (M_EXT_WRITABLE(m) ? (m)->m_data - (m)->m_ext.ext_buf : 0): \
 367             (m)->m_flags & M_PKTHDR ? (m)->m_data - (m)->m_pktdat :     \
 368             (m)->m_data - (m)->m_dat)
 369
 370 /*
 371  * Compute the amount of space available after the end of data in an mbuf.
 372  * The M_WRITABLE() is a temporary, conservative safety measure: the burden
 373  * of checking writability of the mbuf data area rests solely with the caller.
 374  */
 375 #define M_TRAILINGSPACE(m)                                              \
 376         ((m)->m_flags & M_EXT ?                                         \
 377             (M_WRITABLE(m) ? (m)->m_ext.ext_buf + (m)->m_ext.ext_size   \
 378                 - ((m)->m_data + (m)->m_len) : 0) :                     \
 379             &(m)->m_dat[MLEN] - ((m)->m_data + (m)->m_len))
 380
 381 /*
 382  * Arrange to prepend space of size plen to mbuf m.
 383  * If a new mbuf must be allocated, how specifies whether to wait.
 384  * If how is MB_DONTWAIT and allocation fails, the original mbuf chain
 385  * is freed and m is set to NULL.
 386  */
 387 #define M_PREPEND(m, plen, how) do {                                    \
 388         struct mbuf **_mmp = &(m);                                      \
 389         struct mbuf *_mm = *_mmp;                                       \
 390         int _mplen = (plen);                                            \
 391         int __mhow = (how);                                             \
 392                                                                         \
 393         if (M_LEADINGSPACE(_mm) >= _mplen) {                            \
 394                 _mm->m_data -= _mplen;                                  \
 395                 _mm->m_len += _mplen;                                   \
 396         } else                                                          \
 397                 _mm = m_prepend(_mm, _mplen, __mhow);                   \
 398         if (_mm != NULL && _mm->m_flags & M_PKTHDR)                     \
 399                 _mm->m_pkthdr.len += _mplen;                            \
 400         *_mmp = _mm;                                                    \
 401 } while (0)
 402
 403 /* Length to m_copy to copy all. */
 404 #define M_COPYALL       1000000000
 405
 406 /* Compatibility with 4.3 */
 407 #define m_copy(m, o, l) m_copym((m), (o), (l), MB_DONTWAIT)
 408
 409 #ifdef _KERNEL
 410 extern  u_int            m_clalloc_wid; /* mbuf cluster wait count */
 411 extern  u_int            m_mballoc_wid; /* mbuf wait count */
 412 extern  int              max_linkhdr;   /* largest link-level header */
 413 extern  int              max_protohdr;  /* largest protocol header */
 414 extern  int              max_hdr;       /* largest link+protocol header */
 415 extern  int              max_datalen;   /* MHLEN - max_hdr */
 416 extern  struct mbstat    mbstat;
 417 extern  int              mbuf_wait;     /* mbuf sleep time */
 418 extern  int              nmbclusters;
 419 extern  int              nmbufs;
 420
 421 struct uio;
 422
 423 void             m_adj(struct mbuf *, int);
 424 void             m_cat(struct mbuf *, struct mbuf *);
 425 u_int            m_countm(struct mbuf *m, struct mbuf **lastm, u_int *mbcnt);
 426 void             m_copyback(struct mbuf *, int, int, caddr_t);
 427 void             m_copydata(const struct mbuf *, int, int, caddr_t);
 428 struct  mbuf    *m_copym(const struct mbuf *, int, int, int);
 429 struct  mbuf    *m_copypacket(struct mbuf *, int);
 430 struct  mbuf    *m_defrag(struct mbuf *, int);
 431 struct  mbuf    *m_defrag_nofree(struct mbuf *, int);
 432 struct  mbuf    *m_devget(char *, int, int, struct ifnet *,
 433                   void (*copy)(volatile const void *, volatile void *, size_t));
 434 struct  mbuf    *m_dup(struct mbuf *, int);
 435 int              m_dup_pkthdr(struct mbuf *, const struct mbuf *, int);
 436 struct  mbuf    *m_free(struct mbuf *);
 437 void             m_freem(struct mbuf *);
 438 struct  mbuf    *m_get(int, int);
 439 struct  mbuf    *m_getc(int len, int how, int type);
 440 struct  mbuf    *m_getcl(int how, short type, int flags);
 441 struct  mbuf    *m_getclr(int, int);
 442 struct  mbuf    *m_gethdr(int, int);
 443 struct  mbuf    *m_getm(struct mbuf *, int, int, int);
 444 struct  mbuf    *m_last(struct mbuf *m);
 445 u_int            m_lengthm(struct mbuf *m, struct mbuf **lastm);
 446 void             m_move_pkthdr(struct mbuf *, struct mbuf *);
 447 struct  mbuf    *m_prepend(struct mbuf *, int, int);
 448 void             m_print(const struct mbuf *m);
 449 struct  mbuf    *m_pulldown(struct mbuf *, int, int, int *);
 450 struct  mbuf    *m_pullup(struct mbuf *, int);
 451 struct  mbuf    *m_split(struct mbuf *, int, int);
 452 struct  mbuf    *m_uiomove(struct uio *);
 453 void            m_mclget(struct mbuf *m, int how);
 454 int             m_sharecount(struct mbuf *m);
 455 void            m_chtype(struct mbuf *m, int type);
 456
 457 /*
 458  * Allocate the right type of mbuf for the desired total length.
 459  * The mbuf returned does not necessarily cover the entire requested length.
 460  * This function follows mbuf chaining policy of allowing MINCLSIZE
 461  * amount of chained mbufs.
 462  */
 463 static __inline struct mbuf *
 464 m_getl(int len, int how, int type, int flags, int *psize)
 465 {
 466         struct mbuf *m;
 467         int size;
 468
 469         if (len >= MINCLSIZE) {
 470                 m = m_getcl(how, type, flags);
 471                 size = MCLBYTES;
 472         } else if (flags & M_PKTHDR) {
 473                 m = m_gethdr(how, type);
 474                 size = MHLEN;
 475         } else {
 476                 m = m_get(how, type);
 477                 size = MLEN;
 478         }
 479         if (psize != NULL)
 480                 *psize = size;
 481         return (m);
 482 }
 483
 484 /*
 485  * Get a single mbuf that covers the requested number of bytes.
 486  * This function does not create mbuf chains.  It explicitly marks
 487  * places in the code that abuse mbufs for contiguous data buffers.
 488  */
 489 static __inline struct mbuf *
 490 m_getb(int len, int how, int type, int flags)
 491 {
 492         struct mbuf *m;
 493         int mbufsize = (flags & M_PKTHDR) ? MHLEN : MLEN;
 494
 495         if (len > mbufsize)
 496                 m = m_getcl(how, type, flags);
 497         else if (flags & M_PKTHDR)
 498                 m = m_gethdr(how, type);
 499         else
 500                 m = m_get(how, type);
 501         return (m);
 502 }
 503
 504 /*
 505  * Packets may have annotations attached by affixing a list
 506  * of "packet tags" to the pkthdr structure.  Packet tags are
 507  * dynamically allocated semi-opaque data structures that have
 508  * a fixed header (struct m_tag) that specifies the size of the
 509  * memory block and a <cookie,type> pair that identifies it.
 510  * The cookie is a 32-bit unique unsigned value used to identify
 511  * a module or ABI.  By convention this value is chose as the
 512  * date+time that the module is created, expressed as the number of
 513  * seconds since the epoch (e.g. using date -u +'%s').  The type value
 514  * is an ABI/module-specific value that identifies a particular annotation
 515  * and is private to the module.  For compatibility with systems
 516  * like openbsd that define packet tags w/o an ABI/module cookie,
 517  * the value PACKET_ABI_COMPAT is used to implement m_tag_get and
 518  * m_tag_find compatibility shim functions and several tag types are
 519  * defined below.  Users that do not require compatibility should use
 520  * a private cookie value so that packet tag-related definitions
 521  * can be maintained privately.
 522  *
 523  * Note that the packet tag returned by m_tag_allocate has the default
 524  * memory alignment implemented by malloc.  To reference private data
 525  * one can use a construct like:
 526  *
 527  *      struct m_tag *mtag = m_tag_allocate(...);
 528  *      struct foo *p = (struct foo *)(mtag+1);
 529  *
 530  * if the alignment of struct m_tag is sufficient for referencing members
 531  * of struct foo.  Otherwise it is necessary to embed struct m_tag within
 532  * the private data structure to insure proper alignment; e.g.
 533  *
 534  *      struct foo {
 535  *              struct m_tag    tag;
 536  *              ...
 537  *      };
 538  *      struct foo *p = (struct foo *) m_tag_allocate(...);
 539  *      struct m_tag *mtag = &p->tag;
 540  */
 541
 542 #define PACKET_TAG_NONE                         0  /* Nadda */
 543
 544 /* Packet tag for use with PACKET_ABI_COMPAT */
 545 #define PACKET_TAG_IPSEC_IN_DONE                1  /* IPsec applied, in */
 546 /* struct tdb_indent */
 547 #define PACKET_TAG_IPSEC_OUT_DONE               2  /* IPsec applied, out */
 548 /* struct tdb_indent */
 549 #define PACKET_TAG_IPSEC_IN_CRYPTO_DONE         3  /* NIC IPsec crypto done */
 550 /* struct tdb_indent, never added */
 551 #define PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED      4  /* NIC IPsec crypto req'ed */
 552 /* struct tdb_indent, never added */
 553 #define PACKET_TAG_IPSEC_PENDING_TDB            5  /* Reminder to do IPsec */
 554 /* struct tdb_indent, never added */
 555 #define PACKET_TAG_ENCAP                        6 /* Encap.  processing */
 556 /* struct ifnet *, the GIF interface */
 557 #define PACKET_TAG_IPSEC_HISTORY                7 /* IPSEC history */
 558 /* struct ipsec_history */
 559 #define PACKET_TAG_IPV6_INPUT                   8 /* IPV6 input processing */
 560 /* struct ip6aux */
 561 #define PACKET_TAG_IPFW_DIVERT                  9 /* divert info */
 562 /* uint16_t */
 563
 564 /*
 565  * As a temporary and low impact solution to replace the even uglier
 566  * approach used so far in some parts of the network stack (which relies
 567  * on global variables), packet tag-like annotations are stored in MT_TAG
 568  * mbufs (or lookalikes) prepended to the actual mbuf chain.
 569  *
 570  *      m_type  = MT_TAG
 571  *      m_flags = m_tag_id
 572  *      m_next  = next buffer in chain.
 573  *
 574  * BE VERY CAREFUL not to pass these blocks to the mbuf handling routines.
 575  */
 576 #define _m_tag_id       m_hdr.mh_flags
 577
 578 /* Packet tags used in the FreeBSD network stack */
 579 #define PACKET_TAG_DUMMYNET                     15 /* dummynet info */
 580 /* struct dn_pkt as fake mbuf */
 581 #define PACKET_TAG_IPFORWARD                    18 /* ipforward info */
 582 /* struct sockaddr_in * as m_data */
 583
 584 /* Packet tag routines */
 585 struct  m_tag   *m_tag_alloc(u_int32_t, int, int, int);
 586 void             m_tag_free(struct m_tag *);
 587 void             m_tag_prepend(struct mbuf *, struct m_tag *);
 588 void             m_tag_unlink(struct mbuf *, struct m_tag *);
 589 void             m_tag_delete(struct mbuf *, struct m_tag *);
 590 void             m_tag_delete_chain(struct mbuf *);
 591 struct  m_tag   *m_tag_locate(struct mbuf *, u_int32_t, int, struct m_tag *);
 592 struct  m_tag   *m_tag_copy(struct m_tag *, int);
 593 int              m_tag_copy_chain(struct mbuf *, const struct mbuf *, int);
 594 void             m_tag_init(struct mbuf *);
 595 struct  m_tag   *m_tag_first(struct mbuf *);
 596 struct  m_tag   *m_tag_next(struct mbuf *, struct m_tag *);
 597
 598 /* these are for openbsd compatibility */
 599 #define MTAG_ABI_COMPAT         0               /* compatibility ABI */
 600
 601 static __inline void *
 602 m_tag_data(struct m_tag *tag)
 603 {
 604         return ((void *)(tag + 1));
 605 }
 606
 607 static __inline struct m_tag *
 608 m_tag_get(int type, int length, int wait)
 609 {
 610         return m_tag_alloc(MTAG_ABI_COMPAT, type, length, wait);
 611 }
 612
 613 static __inline struct m_tag *
 614 m_tag_find(struct mbuf *m, int type, struct m_tag *start)
 615 {
 616         return m_tag_locate(m, MTAG_ABI_COMPAT, type, start);
 617 }
 618
 619 #endif  /* _KERNEL */
 620
 621 #endif  /* _KERNEL || _KERNEL_STRUCTURES */
 622 #endif  /* !_SYS_MBUF_H_ */