slirp/mbuf.h

   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      8.3 (Berkeley) 1/21/94
  30  * mbuf.h,v 1.9 1994/11/14 13:54:20 bde Exp
  31  */
  32
  33 #ifndef _MBUF_H_
  34 #define _MBUF_H_
  35
  36 #define MINCSIZE 4096   /* Amount to increase mbuf if too small */
  37
  38 /*
  39  * Macros for type conversion
  40  * mtod(m,t) -  convert mbuf pointer to data pointer of correct type
  41  */
  42 #define mtod(m,t)       ((t)(m)->m_data)
  43
  44 /* XXX About mbufs for slirp:
  45  * Only one mbuf is ever used in a chain, for each "cell" of data.
  46  * m_nextpkt points to the next packet, if fragmented.
  47  * If the data is too large, the M_EXT is used, and a larger block
  48  * is alloced.  Therefore, m_free[m] must check for M_EXT and if set
  49  * free the m_ext.  This is inefficient memory-wise, but who cares.
  50  */
  51
  52 /* XXX should union some of these! */
  53 /* header at beginning of each mbuf: */
  54 struct m_hdr {
  55         struct  mbuf *mh_next;          /* Linked list of mbufs */
  56         struct  mbuf *mh_prev;
  57         struct  mbuf *mh_nextpkt;       /* Next packet in queue/record */
  58         struct  mbuf *mh_prevpkt; /* Flags aren't used in the output queue */
  59         int     mh_flags;         /* Misc flags */
  60
  61         int     mh_size;                /* Size of data */
  62         struct  socket *mh_so;
  63
  64         caddr_t mh_data;                /* Location of data */
  65         int     mh_len;                 /* Amount of data in this mbuf */
  66 };
  67
  68 /*
  69  * How much room is in the mbuf, from m_data to the end of the mbuf
  70  */
  71 #define M_ROOM(m) ((m->m_flags & M_EXT)? \
  72                         (((m)->m_ext + (m)->m_size) - (m)->m_data) \
  73                    : \
  74                         (((m)->m_dat + (m)->m_size) - (m)->m_data))
  75
  76 /*
  77  * How much free room there is
  78  */
  79 #define M_FREEROOM(m) (M_ROOM(m) - (m)->m_len)
  80 #define M_TRAILINGSPACE M_FREEROOM
  81
  82 struct mbuf {
  83         struct  m_hdr m_hdr;
  84         Slirp *slirp;
  85         union M_dat {
  86                 char    m_dat_[1]; /* ANSI don't like 0 sized arrays */
  87                 char    *m_ext_;
  88         } M_dat;
  89 };
  90
  91 #define m_next          m_hdr.mh_next
  92 #define m_prev          m_hdr.mh_prev
  93 #define m_nextpkt       m_hdr.mh_nextpkt
  94 #define m_prevpkt       m_hdr.mh_prevpkt
  95 #define m_flags         m_hdr.mh_flags
  96 #define m_len           m_hdr.mh_len
  97 #define m_data          m_hdr.mh_data
  98 #define m_size          m_hdr.mh_size
  99 #define m_dat           M_dat.m_dat_
 100 #define m_ext           M_dat.m_ext_
 101 #define m_so            m_hdr.mh_so
 102
 103 #define ifq_prev m_prev
 104 #define ifq_next m_next
 105 #define ifs_prev m_prevpkt
 106 #define ifs_next m_nextpkt
 107 #define ifq_so m_so
 108
 109 #define M_EXT                   0x01    /* m_ext points to more (malloced) data */
 110 #define M_FREELIST              0x02    /* mbuf is on free list */
 111 #define M_USEDLIST              0x04    /* XXX mbuf is on used list (for dtom()) */
 112 #define M_DOFREE                0x08    /* when m_free is called on the mbuf, free()
 113                                          * it rather than putting it on the free list */
 114
 115 void m_init(Slirp *);
 116 struct mbuf * m_get(Slirp *);
 117 void m_free(struct mbuf *);
 118 void m_cat(register struct mbuf *, register struct mbuf *);
 119 void m_inc(struct mbuf *, int);
 120 void m_adj(struct mbuf *, int);
 121 int m_copy(struct mbuf *, struct mbuf *, int, int);
 122 struct mbuf * dtom(Slirp *, void *);
 123
 124 #endif