slirp/src/mbuf.h

   1 /* SPDX-License-Identifier: BSD-3-Clause */
   2 /*
   3  * Copyright (c) 1982, 1986, 1988, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Neither the name of the University nor the names of its contributors
  15  *    may be used to endorse or promote products derived from this software
  16  *    without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  *
  30  *      @(#)mbuf.h      8.3 (Berkeley) 1/21/94
  31  * mbuf.h,v 1.9 1994/11/14 13:54:20 bde Exp
  32  */
  33
  34 #ifndef MBUF_H
  35 #define MBUF_H
  36
  37 /*
  38  * Macros for type conversion
  39  * mtod(m,t) -  convert mbuf pointer to data pointer of correct type
  40  */
  41 #define mtod(m,t)       ((t)(m)->m_data)
  42
  43 /* XXX About mbufs for slirp:
  44  * Only one mbuf is ever used in a chain, for each "cell" of data.
  45  * m_nextpkt points to the next packet, if fragmented.
  46  * If the data is too large, the M_EXT is used, and a larger block
  47  * is alloced.  Therefore, m_free[m] must check for M_EXT and if set
  48  * free the m_ext.  This is inefficient memory-wise, but who cares.
  49  */
  50
  51 /*
  52  * mbufs allow to have a gap between the start of the allocated buffer (m_ext if
  53  * M_EXT is set, m_dat otherwise) and the in-use data:
  54  *
  55  *  |--gapsize----->|---m_len------->
  56  *  |----------m_size------------------------------>
  57  *                  |----M_ROOM-------------------->
  58  *                                   |-M_FREEROOM-->
  59  *
  60  *  ^               ^                               ^
  61  *  m_dat/m_ext     m_data                          end of buffer
  62  */
  63
  64 /*
  65  * How much room is in the mbuf, from m_data to the end of the mbuf
  66  */
  67 #define M_ROOM(m) ((m->m_flags & M_EXT)? \
  68                         (((m)->m_ext + (m)->m_size) - (m)->m_data) \
  69                    : \
  70                         (((m)->m_dat + (m)->m_size) - (m)->m_data))
  71
  72 /*
  73  * How much free room there is
  74  */
  75 #define M_FREEROOM(m) (M_ROOM(m) - (m)->m_len)
  76
  77 struct mbuf {
  78         /* XXX should union some of these! */
  79         /* header at beginning of each mbuf: */
  80         struct  mbuf *m_next;           /* Linked list of mbufs */
  81         struct  mbuf *m_prev;
  82         struct  mbuf *m_nextpkt;        /* Next packet in queue/record */
  83         struct  mbuf *m_prevpkt;        /* Flags aren't used in the output queue */
  84         int     m_flags;                /* Misc flags */
  85
  86         int     m_size;                 /* Size of mbuf, from m_dat or m_ext */
  87         struct  socket *m_so;
  88
  89         char *m_data;                   /* Current location of data */
  90         int     m_len;                  /* Amount of data in this mbuf, from m_data */
  91
  92         Slirp *slirp;
  93         bool    resolution_requested;
  94         uint64_t expiration_date;
  95         char   *m_ext;
  96         /* start of dynamic buffer area, must be last element */
  97         char    m_dat[];
  98 };
  99
 100 #define ifq_prev m_prev
 101 #define ifq_next m_next
 102 #define ifs_prev m_prevpkt
 103 #define ifs_next m_nextpkt
 104 #define ifq_so m_so
 105
 106 #define M_EXT                   0x01    /* m_ext points to more (malloced) data */
 107 #define M_FREELIST              0x02    /* mbuf is on free list */
 108 #define M_USEDLIST              0x04    /* XXX mbuf is on used list (for dtom()) */
 109 #define M_DOFREE                0x08    /* when m_free is called on the mbuf, free()
 110                                          * it rather than putting it on the free list */
 111
 112 void m_init(Slirp *);
 113 void m_cleanup(Slirp *slirp);
 114 struct mbuf * m_get(Slirp *);
 115 void m_free(struct mbuf *);
 116 void m_cat(register struct mbuf *, register struct mbuf *);
 117 void m_inc(struct mbuf *, int);
 118 void m_adj(struct mbuf *, int);
 119 int m_copy(struct mbuf *, struct mbuf *, int, int);
 120 struct mbuf * dtom(Slirp *, void *);
 121
 122 static inline void ifs_init(struct mbuf *ifm)
 123 {
 124     ifm->ifs_next = ifm->ifs_prev = ifm;
 125 }
 126
 127 #endif