bsd/netinet/in_cksum.c

   1 /*
   2  * Copyright (c) 2000-2009 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * Copyright (c) 1988, 1992, 1993
  30  *      The Regents of the University of California.  All rights reserved.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  *
  60  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
  61  */
  62
  63 #include <sys/param.h>
  64 #include <sys/mbuf.h>
  65 #include <sys/kdebug.h>
  66 #include <kern/debug.h>
  67 #include <netinet/in.h>
  68 #include <netinet/ip.h>
  69 #include <libkern/libkern.h>
  70
  71 #define DBG_FNC_IN_CKSUM        NETDBG_CODE(DBG_NETIP, (3 << 8))
  72
  73 /*
  74  * Checksum routine for Internet Protocol family headers (Portable Version).
  75  *
  76  * This routine is very heavily used in the network
  77  * code and should be modified for each CPU to be as fast as possible.
  78  */
  79
  80 union s_util {
  81         char    c[2];
  82         u_short s;
  83 };
  84
  85 union l_util {
  86         u_int16_t s[2];
  87         u_int32_t l;
  88 };
  89
  90 union q_util {
  91         u_int16_t s[4];
  92         u_int32_t l[2];
  93         u_int64_t q;
  94 };
  95
  96 #define ADDCARRY(x)  do { if (x > 65535) { x -= 65535; } } while (0)
  97
  98 #define REDUCE32                                                          \
  99     {                                                                     \
 100         q_util.q = sum;                                                   \
 101         sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];      \
 102     }
 103 #define REDUCE16                                                          \
 104     {                                                                     \
 105         q_util.q = sum;                                                   \
 106         l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
 107         sum = l_util.s[0] + l_util.s[1];                                  \
 108         ADDCARRY(sum);                                                    \
 109     }
 110
 111 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
 112
 113 u_int16_t inet_cksum_simple(struct mbuf *, int);
 114
 115 u_int16_t
 116 inet_cksum_simple(struct mbuf *m, int len)
 117 {
 118         return (inet_cksum(m, 0, 0, len));
 119 }
 120
 121 u_short
 122 in_addword(u_short a, u_short b)
 123 {
 124         union l_util l_util;
 125         u_int32_t sum = a + b;
 126
 127         REDUCE;
 128         return (sum);
 129 }
 130
 131 u_short
 132 in_pseudo(u_int a, u_int b, u_int c)
 133 {
 134         u_int64_t sum;
 135         union q_util q_util;
 136         union l_util l_util;
 137
 138         sum = (u_int64_t) a + b + c;
 139         REDUCE16;
 140         return (sum);
 141
 142 }
 143
 144
 145 u_int16_t
 146 inet_cksum(struct mbuf *m, unsigned int nxt, unsigned int skip,
 147     unsigned int len)
 148 {
 149         u_short *w;
 150         u_int32_t sum = 0;
 151         int mlen = 0;
 152         int byte_swapped = 0;
 153         union s_util s_util;
 154         union l_util l_util;
 155
 156         KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_START, len,0,0,0,0);
 157
 158         /* sanity check */
 159         if ((m->m_flags & M_PKTHDR) && m->m_pkthdr.len < skip + len) {
 160                 panic("inet_cksum: mbuf len (%d) < off+len (%d+%d)\n",
 161                     m->m_pkthdr.len, skip, len);
 162         }
 163
 164         /* include pseudo header checksum? */
 165         if (nxt != 0) {
 166                 struct ip *iph;
 167
 168                 if (m->m_len < sizeof (struct ip))
 169                         panic("inet_cksum: bad mbuf chain");
 170
 171                 iph = mtod(m, struct ip *);
 172                 sum = in_pseudo(iph->ip_src.s_addr, iph->ip_dst.s_addr,
 173                     htonl(len + nxt));
 174         }
 175
 176         if (skip != 0) {
 177                 for (; skip && m; m = m->m_next) {
 178                         if (m->m_len > skip) {
 179                                 mlen = m->m_len - skip;
 180                                 w = (u_short *)(void *)(m->m_data+skip);
 181                                 goto skip_start;
 182                         } else {
 183                                 skip -= m->m_len;
 184                         }
 185                 }
 186         }
 187         for (;m && len; m = m->m_next) {
 188                 if (m->m_len == 0)
 189                         continue;
 190                 w = mtod(m, u_short *);
 191
 192                 if (mlen == -1) {
 193                         /*
 194                          * The first byte of this mbuf is the continuation
 195                          * of a word spanning between this mbuf and the
 196                          * last mbuf.
 197                          *
 198                          * s_util.c[0] is already saved when scanning previous
 199                          * mbuf.
 200                          */
 201                         s_util.c[1] = *(char *)w;
 202                         sum += s_util.s;
 203                         w = (u_short *)(void *)((char *)w + 1);
 204                         mlen = m->m_len - 1;
 205                         len--;
 206                 } else {
 207                         mlen = m->m_len;
 208                 }
 209 skip_start:
 210                 if (len < mlen)
 211                         mlen = len;
 212
 213                 len -= mlen;
 214                 /*
 215                  * Force to even boundary.
 216                  */
 217                 if ((1 & (uintptr_t) w) && (mlen > 0)) {
 218                         REDUCE;
 219                         sum <<= 8;
 220                         s_util.c[0] = *(u_char *)w;
 221                         w = (u_short *)(void *)((char *)w + 1);
 222                         mlen--;
 223                         byte_swapped = 1;
 224                 }
 225                 /*
 226                  * Unroll the loop to make overhead from
 227                  * branches &c small.
 228                  */
 229                 while ((mlen -= 32) >= 0) {
 230                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 231                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 232                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 233                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 234                         w += 16;
 235                 }
 236                 mlen += 32;
 237                 while ((mlen -= 8) >= 0) {
 238                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 239                         w += 4;
 240                 }
 241                 mlen += 8;
 242                 if (mlen == 0 && byte_swapped == 0)
 243                         continue;
 244                 REDUCE;
 245                 while ((mlen -= 2) >= 0) {
 246                         sum += *w++;
 247                 }
 248                 if (byte_swapped) {
 249                         REDUCE;
 250                         sum <<= 8;
 251                         byte_swapped = 0;
 252                         if (mlen == -1) {
 253                                 s_util.c[1] = *(char *)w;
 254                                 sum += s_util.s;
 255                                 mlen = 0;
 256                         } else
 257                                 mlen = -1;
 258                 } else if (mlen == -1)
 259                         s_util.c[0] = *(char *)w;
 260         }
 261         if (len)
 262                 printf("cksum: out of data by %d\n", len);
 263         if (mlen == -1) {
 264                 /* The last mbuf has odd # of bytes. Follow the
 265                    standard (the odd byte may be shifted left by 8 bits
 266                    or not as determined by endian-ness of the machine) */
 267                 s_util.c[1] = 0;
 268                 sum += s_util.s;
 269         }
 270         REDUCE;
 271         KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_END, 0,0,0,0,0);
 272         return (~sum & 0xffff);
 273 }
 274