LXR qemu/slirp/cksum.c

   1/*
   2 * Copyright (c) 1988, 1992, 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 *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
  30 * in_cksum.c,v 1.2 1994/08/02 07:48:16 davidg Exp
  31 */
  32
  33#include "qemu/osdep.h"
  34#include "slirp.h"
  35
  36/*
  37 * Checksum routine for Internet Protocol family headers (Portable Version).
  38 *
  39 * This routine is very heavily used in the network
  40 * code and should be modified for each CPU to be as fast as possible.
  41 *
  42 * XXX Since we will never span more than 1 mbuf, we can optimise this
  43 */
  44
  45#define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
  46#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1];        \
  47        (void)ADDCARRY(sum);}
  48
  49int cksum(struct mbuf *m, int len)
  50{
  51        register uint16_t *w;
  52        register int sum = 0;
  53        register int mlen = 0;
  54        int byte_swapped = 0;
  55
  56        union {
  57                uint8_t  c[2];
  58                uint16_t s;
  59        } s_util;
  60        union {
  61                uint16_t s[2];
  62                uint32_t l;
  63        } l_util;
  64
  65        if (m->m_len == 0)
  66           goto cont;
  67        w = mtod(m, uint16_t *);
  68
  69        mlen = m->m_len;
  70
  71        if (len < mlen)
  72           mlen = len;
  73#ifdef DEBUG
  74        len -= mlen;
  75#endif
  76        /*
  77         * Force to even boundary.
  78         */
  79        if ((1 & (uintptr_t)w) && (mlen > 0)) {
  80                REDUCE;
  81                sum <<= 8;
  82                s_util.c[0] = *(uint8_t *)w;
  83                w = (uint16_t *)((int8_t *)w + 1);
  84                mlen--;
  85                byte_swapped = 1;
  86        }
  87        /*
  88         * Unroll the loop to make overhead from
  89         * branches &c small.
  90         */
  91        while ((mlen -= 32) >= 0) {
  92                sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  93                sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  94                sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  95                sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  96                w += 16;
  97        }
  98        mlen += 32;
  99        while ((mlen -= 8) >= 0) {
 100                sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 101                w += 4;
 102        }
 103        mlen += 8;
 104        if (mlen == 0 && byte_swapped == 0)
 105           goto cont;
 106        REDUCE;
 107        while ((mlen -= 2) >= 0) {
 108                sum += *w++;
 109        }
 110
 111        if (byte_swapped) {
 112                REDUCE;
 113                sum <<= 8;
 114                if (mlen == -1) {
 115                        s_util.c[1] = *(uint8_t *)w;
 116                        sum += s_util.s;
 117                        mlen = 0;
 118                } else
 119
 120                   mlen = -1;
 121        } else if (mlen == -1)
 122           s_util.c[0] = *(uint8_t *)w;
 123
 124cont:
 125#ifdef DEBUG
 126        if (len) {
 127                DEBUG_ERROR((dfd, "cksum: out of data\n"));
 128                DEBUG_ERROR((dfd, " len = %d\n", len));
 129        }
 130#endif
 131        if (mlen == -1) {
 132                /* The last mbuf has odd # of bytes. Follow the
 133                 standard (the odd byte may be shifted left by 8 bits
 134                           or not as determined by endian-ness of the machine) */
 135                s_util.c[1] = 0;
 136                sum += s_util.s;
 137        }
 138        REDUCE;
 139        return (~sum & 0xffff);
 140}
 141
 142int ip6_cksum(struct mbuf *m)
 143{
 144    /* TODO: Optimize this by being able to pass the ip6_pseudohdr to cksum
 145     * separately from the mbuf */
 146    struct ip6 save_ip, *ip = mtod(m, struct ip6 *);
 147    struct ip6_pseudohdr *ih = mtod(m, struct ip6_pseudohdr *);
 148    int sum;
 149
 150    save_ip = *ip;
 151
 152    ih->ih_src = save_ip.ip_src;
 153    ih->ih_dst = save_ip.ip_dst;
 154    ih->ih_pl = htonl((uint32_t)ntohs(save_ip.ip_pl));
 155    ih->ih_zero_hi = 0;
 156    ih->ih_zero_lo = 0;
 157    ih->ih_nh = save_ip.ip_nh;
 158
 159    sum = cksum(m, ((int)sizeof(struct ip6_pseudohdr))
 160                    + ntohl(ih->ih_pl));
 161
 162    *ip = save_ip;
 163
 164    return sum;
 165}
 166