qemu/slirp/ip_output.c
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   1/*
   2 * Copyright (c) 1982, 1986, 1988, 1990, 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 *      @(#)ip_output.c 8.3 (Berkeley) 1/21/94
  30 * ip_output.c,v 1.9 1994/11/16 10:17:10 jkh Exp
  31 */
  32
  33/*
  34 * Changes and additions relating to SLiRP are
  35 * Copyright (c) 1995 Danny Gasparovski.
  36 *
  37 * Please read the file COPYRIGHT for the
  38 * terms and conditions of the copyright.
  39 */
  40
  41#include "qemu/osdep.h"
  42#include <slirp.h>
  43
  44/* Number of packets queued before we start sending
  45 * (to prevent allocing too many mbufs) */
  46#define IF_THRESH 10
  47
  48/*
  49 * IP output.  The packet in mbuf chain m contains a skeletal IP
  50 * header (with len, off, ttl, proto, tos, src, dst).
  51 * The mbuf chain containing the packet will be freed.
  52 * The mbuf opt, if present, will not be freed.
  53 */
  54int
  55ip_output(struct socket *so, struct mbuf *m0)
  56{
  57        Slirp *slirp = m0->slirp;
  58        register struct ip *ip;
  59        register struct mbuf *m = m0;
  60        register int hlen = sizeof(struct ip );
  61        int len, off, error = 0;
  62
  63        DEBUG_CALL("ip_output");
  64        DEBUG_ARG("so = %p", so);
  65        DEBUG_ARG("m0 = %p", m0);
  66
  67        ip = mtod(m, struct ip *);
  68        /*
  69         * Fill in IP header.
  70         */
  71        ip->ip_v = IPVERSION;
  72        ip->ip_off &= IP_DF;
  73        ip->ip_id = htons(slirp->ip_id++);
  74        ip->ip_hl = hlen >> 2;
  75
  76        /*
  77         * If small enough for interface, can just send directly.
  78         */
  79        if ((uint16_t)ip->ip_len <= IF_MTU) {
  80                ip->ip_len = htons((uint16_t)ip->ip_len);
  81                ip->ip_off = htons((uint16_t)ip->ip_off);
  82                ip->ip_sum = 0;
  83                ip->ip_sum = cksum(m, hlen);
  84
  85                if_output(so, m);
  86                goto done;
  87        }
  88
  89        /*
  90         * Too large for interface; fragment if possible.
  91         * Must be able to put at least 8 bytes per fragment.
  92         */
  93        if (ip->ip_off & IP_DF) {
  94                error = -1;
  95                goto bad;
  96        }
  97
  98        len = (IF_MTU - hlen) &~ 7;       /* ip databytes per packet */
  99        if (len < 8) {
 100                error = -1;
 101                goto bad;
 102        }
 103
 104    {
 105        int mhlen, firstlen = len;
 106        struct mbuf **mnext = &m->m_nextpkt;
 107
 108        /*
 109         * Loop through length of segment after first fragment,
 110         * make new header and copy data of each part and link onto chain.
 111         */
 112        m0 = m;
 113        mhlen = sizeof (struct ip);
 114        for (off = hlen + len; off < (uint16_t)ip->ip_len; off += len) {
 115          register struct ip *mhip;
 116          m = m_get(slirp);
 117          if (m == NULL) {
 118            error = -1;
 119            goto sendorfree;
 120          }
 121          m->m_data += IF_MAXLINKHDR;
 122          mhip = mtod(m, struct ip *);
 123          *mhip = *ip;
 124
 125          m->m_len = mhlen;
 126          mhip->ip_off = ((off - hlen) >> 3) + (ip->ip_off & ~IP_MF);
 127          if (ip->ip_off & IP_MF)
 128            mhip->ip_off |= IP_MF;
 129          if (off + len >= (uint16_t)ip->ip_len)
 130            len = (uint16_t)ip->ip_len - off;
 131          else
 132            mhip->ip_off |= IP_MF;
 133          mhip->ip_len = htons((uint16_t)(len + mhlen));
 134
 135          if (m_copy(m, m0, off, len) < 0) {
 136            error = -1;
 137            goto sendorfree;
 138          }
 139
 140          mhip->ip_off = htons((uint16_t)mhip->ip_off);
 141          mhip->ip_sum = 0;
 142          mhip->ip_sum = cksum(m, mhlen);
 143          *mnext = m;
 144          mnext = &m->m_nextpkt;
 145        }
 146        /*
 147         * Update first fragment by trimming what's been copied out
 148         * and updating header, then send each fragment (in order).
 149         */
 150        m = m0;
 151        m_adj(m, hlen + firstlen - (uint16_t)ip->ip_len);
 152        ip->ip_len = htons((uint16_t)m->m_len);
 153        ip->ip_off = htons((uint16_t)(ip->ip_off | IP_MF));
 154        ip->ip_sum = 0;
 155        ip->ip_sum = cksum(m, hlen);
 156sendorfree:
 157        for (m = m0; m; m = m0) {
 158                m0 = m->m_nextpkt;
 159                m->m_nextpkt = NULL;
 160                if (error == 0)
 161                        if_output(so, m);
 162                else
 163                        m_free(m);
 164        }
 165    }
 166
 167done:
 168        return (error);
 169
 170bad:
 171        m_free(m0);
 172        goto done;
 173}
 174