bsd/netinet/in_cksum.c

   1 /*
   2  * Copyright (c) 2000-2006 Apple Computer, 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
  70 #define DBG_FNC_IN_CKSUM        NETDBG_CODE(DBG_NETIP, (3 << 8))
  71
  72 /*
  73  * Checksum routine for Internet Protocol family headers (Portable Version).
  74  *
  75  * This routine is very heavily used in the network
  76  * code and should be modified for each CPU to be as fast as possible.
  77  */
  78
  79 union s_util {
  80         char    c[2];
  81         u_short s;
  82 };
  83
  84 union l_util {
  85         u_int16_t s[2];
  86         u_int32_t l;
  87 };
  88
  89 union q_util {
  90         u_int16_t s[4];
  91         u_int32_t l[2];
  92         u_int64_t q;
  93 };
  94
  95 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
  96
  97 #define REDUCE32                                                          \
  98     {                                                                     \
  99         q_util.q = sum;                                                   \
 100         sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];      \
 101     }
 102 #define REDUCE16                                                          \
 103     {                                                                     \
 104         q_util.q = sum;                                                   \
 105         l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
 106         sum = l_util.s[0] + l_util.s[1];                                  \
 107         ADDCARRY(sum);                                                    \
 108     }
 109
 110 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
 111
 112 u_int16_t inet_cksum_simple(struct mbuf *, int);
 113
 114 u_int16_t
 115 inet_cksum_simple(struct mbuf *m, int len)
 116 {
 117         return (inet_cksum(m, 0, 0, len));
 118 }
 119
 120 #if defined(__ppc__)
 121
 122 extern u_short xsum_assym(u_short *p, int len, u_short xsum, int odd);
 123
 124 inline u_short
 125 in_addword(u_short a, u_short b)
 126 {
 127         union l_util l_util;
 128         u_int32_t sum = a + b;
 129
 130         REDUCE;
 131         return (sum);
 132 }
 133
 134 inline u_short
 135 in_pseudo(u_int a, u_int b, u_int c)
 136 {
 137         u_int64_t sum;
 138         union q_util q_util;
 139         union l_util l_util;
 140
 141         sum = (u_int64_t) a + b + c;
 142         REDUCE16;
 143         return (sum);
 144
 145 }
 146
 147 u_int16_t
 148 inet_cksum(struct mbuf *m, unsigned int nxt, unsigned int skip,
 149     unsigned int len)
 150 {
 151         u_short *w;
 152         u_int32_t sum = 0;
 153         int mlen = 0;
 154         int starting_on_odd  = 0;
 155
 156         KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_START, len,0,0,0,0);
 157
 158         /* sanity check */
 159         if (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 *)(m->m_data+skip);
 181                                 goto skip_start;
 182                         } else {
 183                                 skip -= m->m_len;
 184                         }
 185                 }
 186         }
 187
 188         for (;m && len; m = m->m_next) {
 189                 if (m->m_len == 0)
 190                         continue;
 191                 mlen = m->m_len;
 192                 w = mtod(m, u_short *);
 193
 194 skip_start:
 195                 if (len < mlen)
 196                         mlen = len;
 197                 sum = xsum_assym(w, mlen, sum, starting_on_odd);
 198                 len -= mlen;
 199                 if (mlen & 0x1)
 200                 {
 201                     if (starting_on_odd)
 202                         starting_on_odd = 0;
 203                     else
 204                         starting_on_odd = 1;
 205                 }
 206         }
 207
 208         KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_END, 0,0,0,0,0);
 209
 210         return (~sum & 0xffff);
 211 }
 212
 213 #else
 214
 215 inline u_short
 216 in_addword(u_short a, u_short b)
 217 {
 218         union l_util l_util;
 219         u_int32_t sum = a + b;
 220
 221         REDUCE(sum);
 222         return (sum);
 223 }
 224
 225 inline u_short
 226 in_pseudo(u_int a, u_int b, u_int c)
 227 {
 228         u_int64_t sum;
 229         union q_util q_util;
 230         union l_util l_util;
 231
 232         sum = (u_int64_t) a + b + c;
 233         REDUCE16;
 234         return (sum);
 235 }
 236
 237 u_int16_t
 238 inet_cksum(struct mbuf *m, unsigned int nxt, unsigned int skip,
 239     unsigned int len)
 240 {
 241         u_short *w;
 242         u_int32_t sum = 0;
 243         int mlen = 0;
 244         int byte_swapped = 0;
 245         union s_util s_util;
 246         union l_util l_util;
 247
 248         KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_START, len,0,0,0,0);
 249
 250         /* sanity check */
 251         if (m->m_pkthdr.len < skip + len) {
 252                 panic("inet_cksum: mbuf len (%d) < off+len (%d+%d)\n",
 253                     m->m_pkthdr.len, skip, len);
 254         }
 255
 256         /* include pseudo header checksum? */
 257         if (nxt != 0) {
 258                 struct ip *iph;
 259
 260                 if (m->m_len < sizeof (struct ip))
 261                         panic("inet_cksum: bad mbuf chain");
 262
 263                 iph = mtod(m, struct ip *);
 264                 sum = in_pseudo(iph->ip_src.s_addr, iph->ip_dst.s_addr,
 265                     htonl(len + nxt));
 266         }
 267
 268         if (skip != 0) {
 269                 for (; skip && m; m = m->m_next) {
 270                         if (m->m_len > skip) {
 271                                 mlen = m->m_len - skip;
 272                                 w = (u_short *)(m->m_data+skip);
 273                                 goto skip_start;
 274                         } else {
 275                                 skip -= m->m_len;
 276                         }
 277                 }
 278         }
 279         for (;m && len; m = m->m_next) {
 280                 if (m->m_len == 0)
 281                         continue;
 282                 w = mtod(m, u_short *);
 283
 284                 if (mlen == -1) {
 285                         /*
 286                          * The first byte of this mbuf is the continuation
 287                          * of a word spanning between this mbuf and the
 288                          * last mbuf.
 289                          *
 290                          * s_util.c[0] is already saved when scanning previous
 291                          * mbuf.
 292                          */
 293                         s_util.c[1] = *(char *)w;
 294                         sum += s_util.s;
 295                         w = (u_short *)((char *)w + 1);
 296                         mlen = m->m_len - 1;
 297                         len--;
 298                 } else {
 299                         mlen = m->m_len;
 300                 }
 301 skip_start:
 302                 if (len < mlen)
 303                         mlen = len;
 304
 305                 len -= mlen;
 306                 /*
 307                  * Force to even boundary.
 308                  */
 309                 if ((1 & (int) w) && (mlen > 0)) {
 310                         REDUCE;
 311                         sum <<= 8;
 312                         s_util.c[0] = *(u_char *)w;
 313                         w = (u_short *)((char *)w + 1);
 314                         mlen--;
 315                         byte_swapped = 1;
 316                 }
 317                 /*
 318                  * Unroll the loop to make overhead from
 319                  * branches &c small.
 320                  */
 321                 while ((mlen -= 32) >= 0) {
 322                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 323                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 324                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 325                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 326                         w += 16;
 327                 }
 328                 mlen += 32;
 329                 while ((mlen -= 8) >= 0) {
 330                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 331                         w += 4;
 332                 }
 333                 mlen += 8;
 334                 if (mlen == 0 && byte_swapped == 0)
 335                         continue;
 336                 REDUCE;
 337                 while ((mlen -= 2) >= 0) {
 338                         sum += *w++;
 339                 }
 340                 if (byte_swapped) {
 341                         REDUCE;
 342                         sum <<= 8;
 343                         byte_swapped = 0;
 344                         if (mlen == -1) {
 345                                 s_util.c[1] = *(char *)w;
 346                                 sum += s_util.s;
 347                                 mlen = 0;
 348                         } else
 349                                 mlen = -1;
 350                 } else if (mlen == -1)
 351                         s_util.c[0] = *(char *)w;
 352         }
 353         if (len)
 354                 printf("cksum: out of data by %d\n", len);
 355         if (mlen == -1) {
 356                 /* The last mbuf has odd # of bytes. Follow the
 357                    standard (the odd byte may be shifted left by 8 bits
 358                    or not as determined by endian-ness of the machine) */
 359                 s_util.c[1] = 0;
 360                 sum += s_util.s;
 361         }
 362         REDUCE;
 363         KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_END, 0,0,0,0,0);
 364         return (~sum & 0xffff);
 365 }
 366
 367 #endif