LXR qemu/slirp/src/cksum.c

   1/* SPDX-License-Identifier: BSD-3-Clause */
   2/*
   3 * Copyright (c) 1988, 1992, 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 *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
  31 * in_cksum.c,v 1.2 1994/08/02 07:48:16 davidg Exp
  32 */
  33
  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        len -= mlen;
  74        /*
  75         * Force to even boundary.
  76         */
  77        if ((1 & (uintptr_t)w) && (mlen > 0)) {
  78                REDUCE;
  79                sum <<= 8;
  80                s_util.c[0] = *(uint8_t *)w;
  81                w = (uint16_t *)((int8_t *)w + 1);
  82                mlen--;
  83                byte_swapped = 1;
  84        }
  85        /*
  86         * Unroll the loop to make overhead from
  87         * branches &c small.
  88         */
  89        while ((mlen -= 32) >= 0) {
  90                sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  91                sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  92                sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  93                sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  94                w += 16;
  95        }
  96        mlen += 32;
  97        while ((mlen -= 8) >= 0) {
  98                sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  99                w += 4;
 100        }
 101        mlen += 8;
 102        if (mlen == 0 && byte_swapped == 0)
 103           goto cont;
 104        REDUCE;
 105        while ((mlen -= 2) >= 0) {
 106                sum += *w++;
 107        }
 108
 109        if (byte_swapped) {
 110                REDUCE;
 111                sum <<= 8;
 112                if (mlen == -1) {
 113                        s_util.c[1] = *(uint8_t *)w;
 114                        sum += s_util.s;
 115                        mlen = 0;
 116                } else
 117
 118                   mlen = -1;
 119        } else if (mlen == -1)
 120           s_util.c[0] = *(uint8_t *)w;
 121
 122cont:
 123        if (len) {
 124                DEBUG_ERROR("cksum: out of data");
 125                DEBUG_ERROR(" len = %d", len);
 126        }
 127        if (mlen == -1) {
 128                /* The last mbuf has odd # of bytes. Follow the
 129                 standard (the odd byte may be shifted left by 8 bits
 130                           or not as determined by endian-ness of the machine) */
 131                s_util.c[1] = 0;
 132                sum += s_util.s;
 133        }
 134        REDUCE;
 135        return (~sum & 0xffff);
 136}
 137
 138int ip6_cksum(struct mbuf *m)
 139{
 140    /* TODO: Optimize this by being able to pass the ip6_pseudohdr to cksum
 141     * separately from the mbuf */
 142    struct ip6 save_ip, *ip = mtod(m, struct ip6 *);
 143    struct ip6_pseudohdr *ih = mtod(m, struct ip6_pseudohdr *);
 144    int sum;
 145
 146    save_ip = *ip;
 147
 148    ih->ih_src = save_ip.ip_src;
 149    ih->ih_dst = save_ip.ip_dst;
 150    ih->ih_pl = htonl((uint32_t)ntohs(save_ip.ip_pl));
 151    ih->ih_zero_hi = 0;
 152    ih->ih_zero_lo = 0;
 153    ih->ih_nh = save_ip.ip_nh;
 154
 155    sum = cksum(m, ((int)sizeof(struct ip6_pseudohdr))
 156                    + ntohl(ih->ih_pl));
 157
 158    *ip = save_ip;
 159
 160    return sum;
 161}
 162