LXR qemu/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
  77struct 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
 112void m_init(Slirp *);
 113void m_cleanup(Slirp *slirp);
 114struct mbuf * m_get(Slirp *);
 115void m_free(struct mbuf *);
 116void m_cat(register struct mbuf *, register struct mbuf *);
 117void m_inc(struct mbuf *, int);
 118void m_adj(struct mbuf *, int);
 119int m_copy(struct mbuf *, struct mbuf *, int, int);
 120struct mbuf * dtom(Slirp *, void *);
 121
 122static inline void ifs_init(struct mbuf *ifm)
 123{
 124    ifm->ifs_next = ifm->ifs_prev = ifm;
 125}
 126
 127#endif
 128