in6_cksum.c

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    1 /*      $OpenBSD: in6_cksum.c,v 1.18 2019/04/22 22:47:49 bluhm Exp $    */
    2 /*      $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $      */
    3 
    4 /*
    5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    6  * All rights reserved.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. Neither the name of the project nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  */
   32 
   33 /*
   34  * Copyright (c) 1988, 1992, 1993
   35  *      The Regents of the University of California.  All rights reserved.
   36  *
   37  * Redistribution and use in source and binary forms, with or without
   38  * modification, are permitted provided that the following conditions
   39  * are met:
   40  * 1. Redistributions of source code must retain the above copyright
   41  *    notice, this list of conditions and the following disclaimer.
   42  * 2. Redistributions in binary form must reproduce the above copyright
   43  *    notice, this list of conditions and the following disclaimer in the
   44  *    documentation and/or other materials provided with the distribution.
   45  * 3. Neither the name of the University nor the names of its contributors
   46  *    may be used to endorse or promote products derived from this software
   47  *    without specific prior written permission.
   48  *
   49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   59  * SUCH DAMAGE.
   60  *
   61  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
   62  */
   63 
   64 #include <sys/param.h>
   65 #include <sys/mbuf.h>
   66 #include <sys/systm.h>
   67 #include <netinet/in.h>
   68 #include <netinet/ip6.h>
   69 
   70 /*
   71  * Checksum routine for Internet Protocol family headers (Portable Version).
   72  *
   73  * This routine is very heavily used in the network
   74  * code and should be modified for each CPU to be as fast as possible.
   75  */
   76 
   77 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
   78 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
   79 
   80 /*
   81  * m MUST contain a continuous IP6 header.
   82  * off is a offset where TCP/UDP/ICMP6 header starts.
   83  * len is a total length of a transport segment.
   84  * (e.g. TCP header + TCP payload)
   85  */
   86 
   87 int
   88 in6_cksum(struct mbuf *m, uint8_t nxt, uint32_t off, uint32_t len)
   89 {
   90         uint16_t *w;
   91         int sum = 0;
   92         int mlen = 0;
   93         int byte_swapped = 0;
   94         struct ip6_hdr *ip6;
   95         union {
   96                 uint16_t phs[4];
   97                 struct {
   98                         uint32_t ph_len;
   99                         uint8_t  ph_zero[3];
  100                         uint8_t  ph_nxt;
  101                 } ph __packed;
  102         } uph;
  103         union {
  104                 uint8_t  c[2];
  105                 uint16_t s;
  106         } s_util;
  107         union {
  108                 uint16_t s[2];
  109                 uint32_t l;
  110         } l_util;
  111 
  112         /* sanity check */
  113         if (m->m_pkthdr.len < off + len) {
  114                 panic("%s: mbuf len (%d) < off+len (%d+%d)",
  115                     __func__, m->m_pkthdr.len, off, len);
  116         }
  117 
  118         /* Skip pseudo-header if nxt == 0. */
  119         if (nxt == 0)
  120                  goto skip_phdr;
  121 
  122         bzero(&uph, sizeof(uph));
  123 
  124         /*
  125          * First create IP6 pseudo header and calculate a summary.
  126          */
  127         ip6 = mtod(m, struct ip6_hdr *);
  128         w = (uint16_t *)&ip6->ip6_src;
  129         uph.ph.ph_len = htonl(len);
  130         uph.ph.ph_nxt = nxt;
  131 
  132         /* IPv6 source address */
  133         sum += w[0];
  134         if (!IN6_IS_SCOPE_EMBED(&ip6->ip6_src))
  135                 sum += w[1];
  136         sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
  137         sum += w[6]; sum += w[7];
  138         /* IPv6 destination address */
  139         sum += w[8];
  140         if (!IN6_IS_SCOPE_EMBED(&ip6->ip6_dst))
  141                 sum += w[9];
  142         sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
  143         sum += w[14]; sum += w[15];
  144         /* Payload length and upper layer identifier */
  145         sum += uph.phs[0];  sum += uph.phs[1];
  146         sum += uph.phs[2];  sum += uph.phs[3];
  147 
  148 skip_phdr:
  149         /*
  150          * Secondly calculate a summary of the first mbuf excluding offset.
  151          */
  152         while (m != NULL && off > 0) {
  153                 if (m->m_len <= off)
  154                         off -= m->m_len;
  155                 else
  156                         break;
  157                 m = m->m_next;
  158         }
  159         if (m == NULL) {
  160                 if  (off)
  161                         panic("%s: out of header, off %u", __func__, off);
  162                 goto end;
  163         }
  164         w = (uint16_t *)(mtod(m, uint8_t *) + off);
  165         mlen = m->m_len - off;
  166         if (len < mlen)
  167                 mlen = len;
  168         len -= mlen;
  169         /*
  170          * Force to even boundary.
  171          */
  172         if ((1 & (long) w) && (mlen > 0)) {
  173                 REDUCE;
  174                 sum <<= 8;
  175                 s_util.c[0] = *(uint8_t *)w;
  176                 w = (uint16_t *)((uint8_t *)w + 1);
  177                 mlen--;
  178                 byte_swapped = 1;
  179         }
  180         /*
  181          * Unroll the loop to make overhead from
  182          * branches &c small.
  183          */
  184         while ((mlen -= 32) >= 0) {
  185                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  186                 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  187                 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  188                 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  189                 w += 16;
  190         }
  191         mlen += 32;
  192         while ((mlen -= 8) >= 0) {
  193                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  194                 w += 4;
  195         }
  196         mlen += 8;
  197         if (mlen == 0 && byte_swapped == 0)
  198                 goto next;
  199         REDUCE;
  200         while ((mlen -= 2) >= 0) {
  201                 sum += *w++;
  202         }
  203         if (byte_swapped) {
  204                 REDUCE;
  205                 sum <<= 8;
  206                 byte_swapped = 0;
  207                 if (mlen == -1) {
  208                         s_util.c[1] = *(uint8_t *)w;
  209                         sum += s_util.s;
  210                         mlen = 0;
  211                 } else
  212                         mlen = -1;
  213         } else if (mlen == -1)
  214                 s_util.c[0] = *(uint8_t *)w;
  215  next:
  216         m = m->m_next;
  217 
  218         /*
  219          * Lastly calculate a summary of the rest of mbufs.
  220          */
  221 
  222         for (;m && len; m = m->m_next) {
  223                 if (m->m_len == 0)
  224                         continue;
  225                 w = mtod(m, uint16_t *);
  226                 if (mlen == -1) {
  227                         /*
  228                          * The first byte of this mbuf is the continuation
  229                          * of a word spanning between this mbuf and the
  230                          * last mbuf.
  231                          *
  232                          * s_util.c[0] is already saved when scanning previous
  233                          * mbuf.
  234                          */
  235                         s_util.c[1] = *(uint8_t *)w;
  236                         sum += s_util.s;
  237                         w = (uint16_t *)((uint8_t *)w + 1);
  238                         mlen = m->m_len - 1;
  239                         len--;
  240                 } else
  241                         mlen = m->m_len;
  242                 if (len < mlen)
  243                         mlen = len;
  244                 len -= mlen;
  245                 /*
  246                  * Force to even boundary.
  247                  */
  248                 if ((1 & (long) w) && (mlen > 0)) {
  249                         REDUCE;
  250                         sum <<= 8;
  251                         s_util.c[0] = *(uint8_t *)w;
  252                         w = (uint16_t *)((uint8_t *)w + 1);
  253                         mlen--;
  254                         byte_swapped = 1;
  255                 }
  256                 /*
  257                  * Unroll the loop to make overhead from
  258                  * branches &c small.
  259                  */
  260                 while ((mlen -= 32) >= 0) {
  261                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  262                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  263                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  264                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  265                         w += 16;
  266                 }
  267                 mlen += 32;
  268                 while ((mlen -= 8) >= 0) {
  269                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  270                         w += 4;
  271                 }
  272                 mlen += 8;
  273                 if (mlen == 0 && byte_swapped == 0)
  274                         continue;
  275                 REDUCE;
  276                 while ((mlen -= 2) >= 0) {
  277                         sum += *w++;
  278                 }
  279                 if (byte_swapped) {
  280                         REDUCE;
  281                         sum <<= 8;
  282                         byte_swapped = 0;
  283                         if (mlen == -1) {
  284                                 s_util.c[1] = *(uint8_t *)w;
  285                                 sum += s_util.s;
  286                                 mlen = 0;
  287                         } else
  288                                 mlen = -1;
  289                 } else if (mlen == -1)
  290                         s_util.c[0] = *(uint8_t *)w;
  291         }
  292  end:
  293         if (len)
  294                 panic("%s: out of data, len %u", __func__, len);
  295         if (mlen == -1) {
  296                 /* The last mbuf has odd # of bytes. Follow the
  297                    standard (the odd byte may be shifted left by 8 bits
  298                    or not as determined by endian-ness of the machine) */
  299                 s_util.c[1] = 0;
  300                 sum += s_util.s;
  301         }
  302         REDUCE;
  303         return (~sum & 0xffff);
  304 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet6/in6_cksum.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet6/in6_cksum.c
