slirp/ip_output.c

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