The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/sys/mbuf.h

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1988, 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  * 3. 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  *      @(#)mbuf.h      8.5 (Berkeley) 2/19/95
   30  * $FreeBSD: releng/5.3/sys/sys/mbuf.h 136588 2004-10-16 08:43:07Z cvs2svn $
   31  */
   32 
   33 #ifndef _SYS_MBUF_H_
   34 #define _SYS_MBUF_H_
   35 
   36 /* XXX: These includes suck. Sorry! */
   37 #include <sys/queue.h>
   38 #ifdef _KERNEL
   39 #include <sys/systm.h>
   40 #include <vm/uma.h>
   41 #ifdef WITNESS
   42 #include <sys/lock.h>
   43 #endif
   44 #endif
   45 
   46 /*
   47  * Mbufs are of a single size, MSIZE (sys/param.h), which
   48  * includes overhead.  An mbuf may add a single "mbuf cluster" of size
   49  * MCLBYTES (also in sys/param.h), which has no additional overhead
   50  * and is used instead of the internal data area; this is done when
   51  * at least MINCLSIZE of data must be stored.  Additionally, it is possible
   52  * to allocate a separate buffer externally and attach it to the mbuf in
   53  * a way similar to that of mbuf clusters.
   54  */
   55 #define MLEN            (MSIZE - sizeof(struct m_hdr))  /* normal data len */
   56 #define MHLEN           (MLEN - sizeof(struct pkthdr))  /* data len w/pkthdr */
   57 #define MINCLSIZE       (MHLEN + 1)     /* smallest amount to put in cluster */
   58 #define M_MAXCOMPRESS   (MHLEN / 2)     /* max amount to copy for compression */
   59 
   60 #ifdef _KERNEL
   61 /*-
   62  * Macros for type conversion:
   63  * mtod(m, t)   -- Convert mbuf pointer to data pointer of correct type.
   64  * dtom(x)      -- Convert data pointer within mbuf to mbuf pointer (XXX).
   65  */
   66 #define mtod(m, t)      ((t)((m)->m_data))
   67 #define dtom(x)         ((struct mbuf *)((intptr_t)(x) & ~(MSIZE-1)))
   68 
   69 /*
   70  * Argument structure passed to UMA routines during mbuf and packet
   71  * allocations.
   72  */
   73 struct mb_args {
   74         int     flags;  /* Flags for mbuf being allocated */
   75         short   type;   /* Type of mbuf being allocated */
   76 };
   77 #endif /* _KERNEL */
   78 
   79 /*
   80  * Header present at the beginning of every mbuf.
   81  */
   82 struct m_hdr {
   83         struct  mbuf *mh_next;          /* next buffer in chain */
   84         struct  mbuf *mh_nextpkt;       /* next chain in queue/record */
   85         caddr_t mh_data;                /* location of data */
   86         int     mh_len;                 /* amount of data in this mbuf */
   87         int     mh_flags;               /* flags; see below */
   88         short   mh_type;                /* type of data in this mbuf */
   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         void                    (*m_tag_free)(struct m_tag *);
  100 };
  101 
  102 /*
  103  * Record/packet header in first mbuf of chain; valid only if M_PKTHDR is set.
  104  */
  105 struct pkthdr {
  106         struct  ifnet *rcvif;           /* rcv interface */
  107         int     len;                    /* total packet length */
  108         /* variables for ip and tcp reassembly */
  109         void    *header;                /* pointer to packet header */
  110         /* variables for hardware checksum */
  111         int     csum_flags;             /* flags regarding checksum */
  112         int     csum_data;              /* data field used by csum routines */
  113         SLIST_HEAD(packet_tags, m_tag) tags; /* list of packet tags */
  114 };
  115 
  116 /*
  117  * Description of external storage mapped into mbuf; valid only if M_EXT is set.
  118  */
  119 struct m_ext {
  120         caddr_t ext_buf;                /* start of buffer */
  121         void    (*ext_free)             /* free routine if not the usual */
  122                     (void *, void *);
  123         void    *ext_args;              /* optional argument pointer */
  124         u_int   ext_size;               /* size of buffer, for ext_free */
  125         u_int   *ref_cnt;               /* pointer to ref count info */
  126         int     ext_type;               /* type of external storage */
  127 };
  128 
  129 /*
  130  * The core of the mbuf object along with some shortcut defines for
  131  * practical purposes.
  132  */
  133 struct mbuf {
  134         struct  m_hdr m_hdr;
  135         union {
  136                 struct {
  137                         struct  pkthdr MH_pkthdr;       /* M_PKTHDR set */
  138                         union {
  139                                 struct  m_ext MH_ext;   /* M_EXT set */
  140                                 char    MH_databuf[MHLEN];
  141                         } MH_dat;
  142                 } MH;
  143                 char    M_databuf[MLEN];                /* !M_PKTHDR, !M_EXT */
  144         } M_dat;
  145 };
  146 #define m_next          m_hdr.mh_next
  147 #define m_len           m_hdr.mh_len
  148 #define m_data          m_hdr.mh_data
  149 #define m_type          m_hdr.mh_type
  150 #define m_flags         m_hdr.mh_flags
  151 #define m_nextpkt       m_hdr.mh_nextpkt
  152 #define m_act           m_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  * mbuf flags.
  160  */
  161 #define M_EXT           0x0001  /* has associated external storage */
  162 #define M_PKTHDR        0x0002  /* start of record */
  163 #define M_EOR           0x0004  /* end of record */
  164 #define M_RDONLY        0x0008  /* associated data is marked read-only */
  165 #define M_PROTO1        0x0010  /* protocol-specific */
  166 #define M_PROTO2        0x0020  /* protocol-specific */
  167 #define M_PROTO3        0x0040  /* protocol-specific */
  168 #define M_PROTO4        0x0080  /* protocol-specific */
  169 #define M_PROTO5        0x0100  /* protocol-specific */
  170 #define M_SKIP_FIREWALL 0x4000  /* skip firewall processing */
  171 #define M_FREELIST      0x8000  /* mbuf is on the free list */
  172 
  173 /*
  174  * mbuf pkthdr flags (also stored in m_flags).
  175  */
  176 #define M_BCAST         0x0200  /* send/received as link-level broadcast */
  177 #define M_MCAST         0x0400  /* send/received as link-level multicast */
  178 #define M_FRAG          0x0800  /* packet is a fragment of a larger packet */
  179 #define M_FIRSTFRAG     0x1000  /* packet is first fragment */
  180 #define M_LASTFRAG      0x2000  /* packet is last fragment */
  181 
  182 /*
  183  * External buffer types: identify ext_buf type.
  184  */
  185 #define EXT_CLUSTER     1       /* mbuf cluster */
  186 #define EXT_SFBUF       2       /* sendfile(2)'s sf_bufs */
  187 #define EXT_PACKET      3       /* came out of Packet zone */
  188 #define EXT_NET_DRV     100     /* custom ext_buf provided by net driver(s) */
  189 #define EXT_MOD_TYPE    200     /* custom module's ext_buf type */
  190 #define EXT_DISPOSABLE  300     /* can throw this buffer away w/page flipping */
  191 #define EXT_EXTREF      400     /* has externally maintained ref_cnt ptr */
  192 
  193 /*
  194  * Flags copied when copying m_pkthdr.
  195  */
  196 #define M_COPYFLAGS     (M_PKTHDR|M_EOR|M_RDONLY|M_PROTO1|M_PROTO1|M_PROTO2|\
  197                             M_PROTO3|M_PROTO4|M_PROTO5|M_SKIP_FIREWALL|\
  198                             M_BCAST|M_MCAST|M_FRAG|M_FIRSTFRAG|M_LASTFRAG)
  199 
  200 /*
  201  * Flags indicating hw checksum support and sw checksum requirements.
  202  */
  203 #define CSUM_IP                 0x0001          /* will csum IP */
  204 #define CSUM_TCP                0x0002          /* will csum TCP */
  205 #define CSUM_UDP                0x0004          /* will csum UDP */
  206 #define CSUM_IP_FRAGS           0x0008          /* will csum IP fragments */
  207 #define CSUM_FRAGMENT           0x0010          /* will do IP fragmentation */
  208 
  209 #define CSUM_IP_CHECKED         0x0100          /* did csum IP */
  210 #define CSUM_IP_VALID           0x0200          /*   ... the csum is valid */
  211 #define CSUM_DATA_VALID         0x0400          /* csum_data field is valid */
  212 #define CSUM_PSEUDO_HDR         0x0800          /* csum_data has pseudo hdr */
  213 
  214 #define CSUM_DELAY_DATA         (CSUM_TCP | CSUM_UDP)
  215 #define CSUM_DELAY_IP           (CSUM_IP)       /* XXX add ipv6 here too? */
  216 
  217 /*
  218  * mbuf types.
  219  */
  220 #define MT_NOTMBUF      0       /* USED INTERNALLY ONLY! Object is not mbuf */
  221 #define MT_DATA         1       /* dynamic (data) allocation */
  222 #define MT_HEADER       2       /* packet header */
  223 #if 0
  224 #define MT_SOCKET       3       /* socket structure */
  225 #define MT_PCB          4       /* protocol control block */
  226 #define MT_RTABLE       5       /* routing tables */
  227 #define MT_HTABLE       6       /* IMP host tables */
  228 #define MT_ATABLE       7       /* address resolution tables */
  229 #endif
  230 #define MT_SONAME       8       /* socket name */
  231 #if 0
  232 #define MT_SOOPTS       10      /* socket options */
  233 #endif
  234 #define MT_FTABLE       11      /* fragment reassembly header */
  235 #if 0
  236 #define MT_RIGHTS       12      /* access rights */
  237 #define MT_IFADDR       13      /* interface address */
  238 #endif
  239 #define MT_CONTROL      14      /* extra-data protocol message */
  240 #define MT_OOBDATA      15      /* expedited data  */
  241 #define MT_NTYPES       16      /* number of mbuf types for mbtypes[] */
  242 
  243 /*
  244  * General mbuf allocator statistics structure.
  245  */
  246 struct mbstat {
  247         u_long  m_mbufs;        /* XXX */
  248         u_long  m_mclusts;      /* XXX */
  249 
  250         u_long  m_drain;        /* times drained protocols for space */
  251         u_long  m_mcfail;       /* XXX: times m_copym failed */
  252         u_long  m_mpfail;       /* XXX: times m_pullup failed */
  253         u_long  m_msize;        /* length of an mbuf */
  254         u_long  m_mclbytes;     /* length of an mbuf cluster */
  255         u_long  m_minclsize;    /* min length of data to allocate a cluster */
  256         u_long  m_mlen;         /* length of data in an mbuf */
  257         u_long  m_mhlen;        /* length of data in a header mbuf */
  258 
  259         /* Number of mbtypes (gives # elems in mbtypes[] array: */
  260         short   m_numtypes;
  261 
  262         /* XXX: Sendfile stats should eventually move to their own struct */
  263         u_long  sf_iocnt;       /* times sendfile had to do disk I/O */
  264         u_long  sf_allocfail;   /* times sfbuf allocation failed */
  265         u_long  sf_allocwait;   /* times sfbuf allocation had to wait */
  266 };
  267 
  268 /*
  269  * Flags specifying how an allocation should be made.
  270  *
  271  * The flag to use is as follows:
  272  * - M_DONTWAIT or M_NOWAIT from an interrupt handler to not block allocation.
  273  * - M_WAIT or M_WAITOK or M_TRYWAIT from wherever it is safe to block.
  274  *
  275  * M_DONTWAIT/M_NOWAIT means that we will not block the thread explicitly
  276  * and if we cannot allocate immediately we may return NULL,
  277  * whereas M_WAIT/M_WAITOK/M_TRYWAIT means that if we cannot allocate
  278  * resources we will block until they are available, and thus never
  279  * return NULL.
  280  *
  281  * XXX Eventually just phase this out to use M_WAITOK/M_NOWAIT.
  282  */
  283 #define MBTOM(how)      (how)
  284 #define M_DONTWAIT      M_NOWAIT
  285 #define M_TRYWAIT       M_WAITOK
  286 #define M_WAIT          M_WAITOK
  287 
  288 #ifdef _KERNEL
  289 /*-
  290  * mbuf external reference count management macros.
  291  *
  292  * MEXT_IS_REF(m): true if (m) is not the only mbuf referencing
  293  *     the external buffer ext_buf.
  294  *
  295  * MEXT_REM_REF(m): remove reference to m_ext object.
  296  *
  297  * MEXT_ADD_REF(m): add reference to m_ext object already
  298  *     referred to by (m).
  299  */
  300 #define MEXT_IS_REF(m)  (*((m)->m_ext.ref_cnt) > 1)
  301 
  302 #define MEXT_REM_REF(m) do {                                            \
  303         KASSERT(*((m)->m_ext.ref_cnt) > 0, ("m_ext refcnt < 0"));       \
  304         atomic_subtract_int((m)->m_ext.ref_cnt, 1);                     \
  305 } while(0)
  306 
  307 #define MEXT_ADD_REF(m) atomic_add_int((m)->m_ext.ref_cnt, 1)
  308 
  309 #ifdef WITNESS
  310 #define MBUF_CHECKSLEEP(how) do {                                       \
  311         if (how == M_WAITOK)                                            \
  312                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,         \
  313                     "Sleeping in \"%s\"", __func__);                    \
  314 } while(0)
  315 #else
  316 #define MBUF_CHECKSLEEP(how)
  317 #endif
  318 
  319 /*
  320  * Network buffer allocation API
  321  *
  322  * The rest of it is defined in kern/subr_mbuf.c
  323  */
  324 
  325 extern uma_zone_t       zone_mbuf;
  326 extern uma_zone_t       zone_clust;
  327 extern uma_zone_t       zone_pack;
  328 
  329 static __inline struct mbuf     *m_get(int how, short type);
  330 static __inline struct mbuf     *m_gethdr(int how, short type);
  331 static __inline struct mbuf     *m_getcl(int how, short type, int flags);
  332 static __inline struct mbuf     *m_getclr(int how, short type); /* XXX */
  333 static __inline struct mbuf     *m_free(struct mbuf *m);
  334 static __inline void             m_clget(struct mbuf *m, int how);
  335 static __inline void             m_chtype(struct mbuf *m, short new_type);
  336 void                             mb_free_ext(struct mbuf *);
  337 
  338 static __inline
  339 struct mbuf *
  340 m_get(int how, short type)
  341 {
  342         struct mb_args args;
  343 
  344         args.flags = 0;
  345         args.type = type;
  346         return (uma_zalloc_arg(zone_mbuf, &args, how));
  347 }
  348 
  349 /* XXX This should be depracated, very little use */
  350 static __inline
  351 struct mbuf *
  352 m_getclr(int how, short type)
  353 {
  354         struct mbuf *m;
  355         struct mb_args args;
  356 
  357         args.flags = 0;
  358         args.type = type;
  359         m = uma_zalloc_arg(zone_mbuf, &args, how);
  360         if (m != NULL)
  361                 bzero(m->m_data, MLEN);
  362         return m;
  363 }
  364 
  365 static __inline
  366 struct mbuf *
  367 m_gethdr(int how, short type)
  368 {
  369         struct mb_args args;
  370 
  371         args.flags = M_PKTHDR;
  372         args.type = type;
  373         return (uma_zalloc_arg(zone_mbuf, &args, how));
  374 }
  375 
  376 static __inline
  377 struct mbuf *
  378 m_getcl(int how, short type, int flags)
  379 {
  380         struct mb_args args;
  381 
  382         args.flags = flags;
  383         args.type = type;
  384         return (uma_zalloc_arg(zone_pack, &args, how));
  385 }
  386 
  387 static __inline
  388 struct mbuf *
  389 m_free(struct mbuf *m)
  390 {
  391         struct mbuf *n = m->m_next;
  392 
  393 #ifdef INVARIANTS
  394         m->m_flags |= M_FREELIST;
  395 #endif
  396         if (m->m_flags & M_EXT)
  397                 mb_free_ext(m);
  398         else
  399                 uma_zfree(zone_mbuf, m);
  400         return n;
  401 }
  402 
  403 static __inline
  404 void
  405 m_clget(struct mbuf *m, int how)
  406 {
  407 
  408         m->m_ext.ext_buf = NULL;
  409         uma_zalloc_arg(zone_clust, m, how);
  410 }
  411 
  412 static __inline
  413 void
  414 m_chtype(struct mbuf *m, short new_type)
  415 {
  416         m->m_type = new_type;
  417 }
  418 
  419 /*
  420  * mbuf, cluster, and external object allocation macros
  421  * (for compatibility purposes).
  422  */
  423 /* NB: M_COPY_PKTHDR is deprecated.  Use M_MOVE_PKTHDR or m_dup_pktdr. */
  424 #define M_MOVE_PKTHDR(to, from) m_move_pkthdr((to), (from))
  425 #define MGET(m, how, type)      ((m) = m_get((how), (type)))
  426 #define MGETHDR(m, how, type)   ((m) = m_gethdr((how), (type)))
  427 #define MCLGET(m, how)          m_clget((m), (how))
  428 #define MEXTADD(m, buf, size, free, args, flags, type)                  \
  429     m_extadd((m), (caddr_t)(buf), (size), (free), (args), (flags), (type))
  430 
  431 /*
  432  * Evaluate TRUE if it's safe to write to the mbuf m's data region (this
  433  * can be both the local data payload, or an external buffer area,
  434  * depending on whether M_EXT is set).
  435  */
  436 #define M_WRITABLE(m)   (!((m)->m_flags & M_RDONLY) && (!((m)->m_flags  \
  437                             & M_EXT) || !MEXT_IS_REF(m)))
  438 
  439 /* Check if the supplied mbuf has a packet header, or else panic. */
  440 #define M_ASSERTPKTHDR(m)                                               \
  441         KASSERT(m != NULL && m->m_flags & M_PKTHDR,                     \
  442             ("%s: no mbuf packet header!", __func__))
  443 
  444 /* Ensure that the supplied mbuf is a valid, non-free mbuf. */
  445 #define M_ASSERTVALID(m)                                                \
  446         KASSERT((((struct mbuf *)m)->m_flags & M_FREELIST) == 0,        \
  447             ("%s: attempted use of a free mbuf!", __func__))
  448 
  449 /*
  450  * Set the m_data pointer of a newly-allocated mbuf (m_get/MGET) to place
  451  * an object of the specified size at the end of the mbuf, longword aligned.
  452  */
  453 #define M_ALIGN(m, len) do {                                            \
  454         (m)->m_data += (MLEN - (len)) & ~(sizeof(long) - 1);            \
  455 } while (0)
  456 
  457 /*
  458  * As above, for mbufs allocated with m_gethdr/MGETHDR
  459  * or initialized by M_COPY_PKTHDR.
  460  */
  461 #define MH_ALIGN(m, len) do {                                           \
  462         (m)->m_data += (MHLEN - (len)) & ~(sizeof(long) - 1);           \
  463 } while (0)
  464 
  465 /*
  466  * Compute the amount of space available
  467  * before the current start of data in an mbuf.
  468  *
  469  * The M_WRITABLE() is a temporary, conservative safety measure: the burden
  470  * of checking writability of the mbuf data area rests solely with the caller.
  471  */
  472 #define M_LEADINGSPACE(m)                                               \
  473         ((m)->m_flags & M_EXT ?                                         \
  474             (M_WRITABLE(m) ? (m)->m_data - (m)->m_ext.ext_buf : 0):     \
  475             (m)->m_flags & M_PKTHDR ? (m)->m_data - (m)->m_pktdat :     \
  476             (m)->m_data - (m)->m_dat)
  477 
  478 /*
  479  * Compute the amount of space available
  480  * after the end of data in an mbuf.
  481  *
  482  * The M_WRITABLE() is a temporary, conservative safety measure: the burden
  483  * of checking writability of the mbuf data area rests solely with the caller.
  484  */
  485 #define M_TRAILINGSPACE(m)                                              \
  486         ((m)->m_flags & M_EXT ?                                         \
  487             (M_WRITABLE(m) ? (m)->m_ext.ext_buf + (m)->m_ext.ext_size   \
  488                 - ((m)->m_data + (m)->m_len) : 0) :                     \
  489             &(m)->m_dat[MLEN] - ((m)->m_data + (m)->m_len))
  490 
  491 /*
  492  * Arrange to prepend space of size plen to mbuf m.
  493  * If a new mbuf must be allocated, how specifies whether to wait.
  494  * If the allocation fails, the original mbuf chain is freed and m is
  495  * set to NULL.
  496  */
  497 #define M_PREPEND(m, plen, how) do {                                    \
  498         struct mbuf **_mmp = &(m);                                      \
  499         struct mbuf *_mm = *_mmp;                                       \
  500         int _mplen = (plen);                                            \
  501         int __mhow = (how);                                             \
  502                                                                         \
  503         MBUF_CHECKSLEEP(how);                                           \
  504         if (M_LEADINGSPACE(_mm) >= _mplen) {                            \
  505                 _mm->m_data -= _mplen;                                  \
  506                 _mm->m_len += _mplen;                                   \
  507         } else                                                          \
  508                 _mm = m_prepend(_mm, _mplen, __mhow);                   \
  509         if (_mm != NULL && _mm->m_flags & M_PKTHDR)                     \
  510                 _mm->m_pkthdr.len += _mplen;                            \
  511         *_mmp = _mm;                                                    \
  512 } while (0)
  513 
  514 /*
  515  * Change mbuf to new type.
  516  * This is a relatively expensive operation and should be avoided.
  517  */
  518 #define MCHTYPE(m, t)   m_chtype((m), (t))
  519 
  520 /* Length to m_copy to copy all. */
  521 #define M_COPYALL       1000000000
  522 
  523 /* Compatibility with 4.3. */
  524 #define m_copy(m, o, l) m_copym((m), (o), (l), M_DONTWAIT)
  525 
  526 extern  int max_datalen;                /* MHLEN - max_hdr */
  527 extern  int max_hdr;                    /* Largest link + protocol header */
  528 extern  int max_linkhdr;                /* Largest link-level header */
  529 extern  int max_protohdr;               /* Largest protocol header */
  530 extern  struct mbstat mbstat;           /* General mbuf stats/infos */
  531 extern  int nmbclusters;                /* Maximum number of clusters */
  532 
  533 struct uio;
  534 
  535 void             m_adj(struct mbuf *, int);
  536 int              m_apply(struct mbuf *, int, int,
  537                     int (*)(void *, void *, u_int), void *);
  538 void             m_cat(struct mbuf *, struct mbuf *);
  539 void             m_extadd(struct mbuf *, caddr_t, u_int,
  540                     void (*)(void *, void *), void *, int, int);
  541 void             m_copyback(struct mbuf *, int, int, c_caddr_t);
  542 void             m_copydata(const struct mbuf *, int, int, caddr_t);
  543 struct  mbuf    *m_copym(struct mbuf *, int, int, int);
  544 struct  mbuf    *m_copypacket(struct mbuf *, int);
  545 void             m_copy_pkthdr(struct mbuf *, struct mbuf *);
  546 struct  mbuf    *m_defrag(struct mbuf *, int);
  547 struct  mbuf    *m_devget(char *, int, int, struct ifnet *,
  548                     void (*)(char *, caddr_t, u_int));
  549 struct  mbuf    *m_dup(struct mbuf *, int);
  550 int              m_dup_pkthdr(struct mbuf *, struct mbuf *, int);
  551 u_int            m_fixhdr(struct mbuf *);
  552 struct  mbuf    *m_fragment(struct mbuf *, int, int);
  553 void             m_freem(struct mbuf *);
  554 struct  mbuf    *m_getm(struct mbuf *, int, int, short);
  555 struct  mbuf    *m_getptr(struct mbuf *, int, int *);
  556 u_int            m_length(struct mbuf *, struct mbuf **);
  557 void             m_move_pkthdr(struct mbuf *, struct mbuf *);
  558 struct  mbuf    *m_prepend(struct mbuf *, int, int);
  559 void             m_print(const struct mbuf *, int);
  560 struct  mbuf    *m_pulldown(struct mbuf *, int, int, int *);
  561 struct  mbuf    *m_pullup(struct mbuf *, int);
  562 struct  mbuf    *m_split(struct mbuf *, int, int);
  563 struct  mbuf    *m_uiotombuf(struct uio *, int, int);
  564 
  565 /*-
  566  * Network packets may have annotations attached by affixing a list
  567  * of "packet tags" to the pkthdr structure.  Packet tags are
  568  * dynamically allocated semi-opaque data structures that have
  569  * a fixed header (struct m_tag) that specifies the size of the
  570  * memory block and a <cookie,type> pair that identifies it.
  571  * The cookie is a 32-bit unique unsigned value used to identify
  572  * a module or ABI.  By convention this value is chose as the
  573  * date+time that the module is created, expressed as the number of
  574  * seconds since the epoch (e.g., using date -u +'%s').  The type value
  575  * is an ABI/module-specific value that identifies a particular annotation
  576  * and is private to the module.  For compatibility with systems
  577  * like OpenBSD that define packet tags w/o an ABI/module cookie,
  578  * the value PACKET_ABI_COMPAT is used to implement m_tag_get and
  579  * m_tag_find compatibility shim functions and several tag types are
  580  * defined below.  Users that do not require compatibility should use
  581  * a private cookie value so that packet tag-related definitions
  582  * can be maintained privately.
  583  *
  584  * Note that the packet tag returned by m_tag_alloc has the default
  585  * memory alignment implemented by malloc.  To reference private data
  586  * one can use a construct like:
  587  *
  588  *      struct m_tag *mtag = m_tag_alloc(...);
  589  *      struct foo *p = (struct foo *)(mtag+1);
  590  *
  591  * if the alignment of struct m_tag is sufficient for referencing members
  592  * of struct foo.  Otherwise it is necessary to embed struct m_tag within
  593  * the private data structure to insure proper alignment; e.g.,
  594  *
  595  *      struct foo {
  596  *              struct m_tag    tag;
  597  *              ...
  598  *      };
  599  *      struct foo *p = (struct foo *) m_tag_alloc(...);
  600  *      struct m_tag *mtag = &p->tag;
  601  */
  602 
  603 /*
  604  * Persistent tags stay with an mbuf until the mbuf is reclaimed.
  605  * Otherwise tags are expected to ``vanish'' when they pass through
  606  * a network interface.  For most interfaces this happens normally
  607  * as the tags are reclaimed when the mbuf is free'd.  However in
  608  * some special cases reclaiming must be done manually.  An example
  609  * is packets that pass through the loopback interface.  Also, one
  610  * must be careful to do this when ``turning around'' packets (e.g.,
  611  * icmp_reflect).
  612  *
  613  * To mark a tag persistent bit-or this flag in when defining the
  614  * tag id.  The tag will then be treated as described above.
  615  */
  616 #define MTAG_PERSISTENT                         0x800
  617 
  618 #define PACKET_TAG_NONE                         0  /* Nadda */
  619 
  620 /* Packet tags for use with PACKET_ABI_COMPAT. */
  621 #define PACKET_TAG_IPSEC_IN_DONE                1  /* IPsec applied, in */
  622 #define PACKET_TAG_IPSEC_OUT_DONE               2  /* IPsec applied, out */
  623 #define PACKET_TAG_IPSEC_IN_CRYPTO_DONE         3  /* NIC IPsec crypto done */
  624 #define PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED      4  /* NIC IPsec crypto req'ed */
  625 #define PACKET_TAG_IPSEC_IN_COULD_DO_CRYPTO     5  /* NIC notifies IPsec */
  626 #define PACKET_TAG_IPSEC_PENDING_TDB            6  /* Reminder to do IPsec */
  627 #define PACKET_TAG_BRIDGE                       7  /* Bridge processing done */
  628 #define PACKET_TAG_GIF                          8  /* GIF processing done */
  629 #define PACKET_TAG_GRE                          9  /* GRE processing done */
  630 #define PACKET_TAG_IN_PACKET_CHECKSUM           10 /* NIC checksumming done */
  631 #define PACKET_TAG_ENCAP                        11 /* Encap.  processing */
  632 #define PACKET_TAG_IPSEC_SOCKET                 12 /* IPSEC socket ref */
  633 #define PACKET_TAG_IPSEC_HISTORY                13 /* IPSEC history */
  634 #define PACKET_TAG_IPV6_INPUT                   14 /* IPV6 input processing */
  635 #define PACKET_TAG_DUMMYNET                     15 /* dummynet info */
  636 #define PACKET_TAG_DIVERT                       17 /* divert info */
  637 #define PACKET_TAG_IPFORWARD                    18 /* ipforward info */
  638 #define PACKET_TAG_MACLABEL     (19 | MTAG_PERSISTENT) /* MAC label */
  639 #define PACKET_TAG_PF_ROUTED                    21 /* PF routed, avoid loops */
  640 #define PACKET_TAG_PF_FRAGCACHE                 22 /* PF fragment cached */
  641 #define PACKET_TAG_PF_QID                       23 /* PF ALTQ queue id */
  642 #define PACKET_TAG_PF_TAG                       24 /* PF tagged */
  643 #define PACKET_TAG_RTSOCKFAM                    25 /* rtsock sa family */
  644 #define PACKET_TAG_PF_TRANSLATE_LOCALHOST       26 /* PF translate localhost */
  645 #define PACKET_TAG_IPOPTIONS                    27 /* Saved IP options */
  646 
  647 /* Packet tag routines. */
  648 struct  m_tag   *m_tag_alloc(u_int32_t, int, int, int);
  649 void             m_tag_delete(struct mbuf *, struct m_tag *);
  650 void             m_tag_delete_chain(struct mbuf *, struct m_tag *);
  651 struct  m_tag   *m_tag_locate(struct mbuf *, u_int32_t, int, struct m_tag *);
  652 struct  m_tag   *m_tag_copy(struct m_tag *, int);
  653 int              m_tag_copy_chain(struct mbuf *, struct mbuf *, int);
  654 void             m_tag_delete_nonpersistent(struct mbuf *);
  655 
  656 /*
  657  * Initialize the list of tags associated with an mbuf.
  658  */
  659 static __inline void
  660 m_tag_init(struct mbuf *m)
  661 {
  662         SLIST_INIT(&m->m_pkthdr.tags);
  663 }
  664 
  665 /*
  666  * Set up the contents of a tag.  Note that this does not
  667  * fill in the free method; the caller is expected to do that.
  668  *
  669  * XXX probably should be called m_tag_init, but that was
  670  * already taken.
  671  */
  672 static __inline void
  673 m_tag_setup(struct m_tag *t, u_int32_t cookie, int type, int len)
  674 {
  675         t->m_tag_id = type;
  676         t->m_tag_len = len;
  677         t->m_tag_cookie = cookie;
  678 }
  679 
  680 /*
  681  * Reclaim resources associated with a tag.
  682  */
  683 static __inline void
  684 m_tag_free(struct m_tag *t)
  685 {
  686         (*t->m_tag_free)(t);
  687 }
  688 
  689 /*
  690  * Return the first tag associated with an mbuf.
  691  */
  692 static __inline struct m_tag *
  693 m_tag_first(struct mbuf *m)
  694 {
  695         return (SLIST_FIRST(&m->m_pkthdr.tags));
  696 }
  697 
  698 /*
  699  * Return the next tag in the list of tags associated with an mbuf.
  700  */
  701 static __inline struct m_tag *
  702 m_tag_next(struct mbuf *m, struct m_tag *t)
  703 {
  704         return (SLIST_NEXT(t, m_tag_link));
  705 }
  706 
  707 /*
  708  * Prepend a tag to the list of tags associated with an mbuf.
  709  */
  710 static __inline void
  711 m_tag_prepend(struct mbuf *m, struct m_tag *t)
  712 {
  713         SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
  714 }
  715 
  716 /*
  717  * Unlink a tag from the list of tags associated with an mbuf.
  718  */
  719 static __inline void
  720 m_tag_unlink(struct mbuf *m, struct m_tag *t)
  721 {
  722         SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
  723 }
  724 
  725 /* These are for OpenBSD compatibility. */
  726 #define MTAG_ABI_COMPAT         0               /* compatibility ABI */
  727 
  728 static __inline struct m_tag *
  729 m_tag_get(int type, int length, int wait)
  730 {
  731         return (m_tag_alloc(MTAG_ABI_COMPAT, type, length, wait));
  732 }
  733 
  734 static __inline struct m_tag *
  735 m_tag_find(struct mbuf *m, int type, struct m_tag *start)
  736 {
  737         return (SLIST_EMPTY(&m->m_pkthdr.tags) ?
  738             NULL : m_tag_locate(m, MTAG_ABI_COMPAT, type, start));
  739 }
  740 
  741 #endif /* _KERNEL */
  742 
  743 #endif /* !_SYS_MBUF_H_ */

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