sys/netiso/iso_chksum.c

   1 /*      $NetBSD: iso_chksum.c,v 1.22 2006/04/14 23:53:53 christos Exp $ */
   2
   3 /*-
   4  * Copyright (c) 1991, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)iso_chksum.c        8.1 (Berkeley) 6/10/93
  32  */
  33
  34 /***********************************************************
  35                 Copyright IBM Corporation 1987
  36
  37                       All Rights Reserved
  38
  39 Permission to use, copy, modify, and distribute this software and its
  40 documentation for any purpose and without fee is hereby granted,
  41 provided that the above copyright notice appear in all copies and that
  42 both that copyright notice and this permission notice appear in
  43 supporting documentation, and that the name of IBM not be
  44 used in advertising or publicity pertaining to distribution of the
  45 software without specific, written prior permission.
  46
  47 IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
  48 ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
  49 IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
  50 ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  51 WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
  52 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  53 SOFTWARE.
  54
  55 ******************************************************************/
  56
  57 /*
  58  * ARGO Project, Computer Sciences Dept., University of Wisconsin - Madison
  59  */
  60 /*
  61  * ISO CHECKSUM
  62  *
  63  * The checksum generation and check routines are here. The checksum is 2 bytes
  64  * such that the sum of all the bytes b(i) == 0 and the sum of i * b(i) == 0.
  65  * The whole thing is complicated by the fact that the data are in mbuf
  66  * chains. Furthermore, there is the possibility of wraparound in the running
  67  * sums after adding up 4102 octets.  In order to avoid doing a mod operation
  68  * after EACH add, we have restricted this implementation to negotiating a
  69  * maximum of 4096-octets per TPDU (for the transport layer). The routine
  70  * iso_check_csum doesn't need to know where the checksum octets are. The
  71  * routine iso_gen_csum takes a pointer to an mbuf chain (logically a chunk
  72  * of data), an offset into the chunk at which the 2 octets are to be
  73  * stuffed, and the length of the chunk.  The 2 octets have to be logically
  74  * adjacent, but may be physically located in separate mbufs.
  75  */
  76
  77 #include <sys/cdefs.h>
  78 __KERNEL_RCSID(1, "$NetBSD: iso_chksum.c,v 1.22 2006/04/14 23:53:53 christos Exp $");
  79
  80 #include "opt_iso.h"
  81
  82 #ifdef ISO
  83 #include <sys/param.h>
  84 #include <sys/systm.h>
  85 #include <sys/mbuf.h>
  86 #include <sys/socket.h>
  87
  88 #include <uvm/uvm_extern.h>
  89
  90 #include <net/if.h>
  91 #include <netiso/argo_debug.h>
  92 #include <netiso/iso.h>
  93 #include <netiso/iso_var.h>
  94 #endif /* ISO */
  95
  96 /*
  97  * FUNCTION:    iso_check_csum
  98  *
  99  * PURPOSE:     To check the checksum of the packet in the mbuf chain (m).
 100  *                      The total length of the packet is (len).
 101  *                      Called from tp_input() and clnp_intr()
 102  *
 103  * RETURNS:      TRUE (something non-zero) if there is a checksum error,
 104  *               FALSE if there was NO checksum error.
 105  *
 106  * SIDE EFFECTS:  none
 107  *
 108  * NOTES:        It might be possible to gain something by optimizing
 109  *               this routine (unrolling loops, etc). But it is such
 110  *               a horrible thing to fiddle with anyway, it probably
 111  *               isn't worth it.
 112  */
 113 int
 114 iso_check_csum(struct mbuf *m, int len)
 115 {
 116         u_char *p = mtod(m, u_char *);
 117         u_long c0 = 0, c1 = 0;
 118         int    i = 0;
 119         int             cum = 0;/* cumulative length */
 120         int             l;
 121
 122         l = len;
 123         len = min(m->m_len, len);
 124         i = 0;
 125
 126 #ifdef ARGO_DEBUG
 127         if (argo_debug[D_CHKSUM]) {
 128                 printf("iso_check_csum: m %p, l x%x, m->m_len x%x\n",
 129                     m, l, m->m_len);
 130         }
 131 #endif
 132
 133         while (i < l) {
 134                 cum += len;
 135                 while (i < cum) {
 136                         c0 = c0 + *(p++);
 137                         c1 += c0;
 138                         i++;
 139                 }
 140                 if (i < l) {
 141                         m = m->m_next;
 142 #ifdef ARGO_DEBUG
 143                         if (argo_debug[D_CHKSUM]) {
 144                                 printf("iso_check_csum: new mbuf\n");
 145                                 if (l - i < m->m_len)
 146                                         printf(
 147                        "bad mbuf chain in check csum l 0x%x i 0x%x m_data %p",
 148                                                l, i, m->m_data);
 149                         }
 150 #endif
 151                         ASSERT(m != NULL);
 152                         len = min(m->m_len, l - i);
 153                         p = mtod(m, u_char *);
 154                 }
 155         }
 156         if (((int) c0 % 255) || ((int) c1 % 255)) {
 157 #ifdef ARGO_DEBUG
 158                 if (argo_debug[D_CHKSUM]) {
 159                         printf("BAD iso_check_csum l 0x%x cum 0x%x len 0x%x, i 0x%x",
 160                             l, cum, len, i);
 161                 }
 162 #endif
 163                 return ((int) c0 % 255) << 8 | ((int) c1 % 255);
 164         }
 165         return 0;
 166 }
 167
 168 /*
 169  * FUNCTION:    iso_gen_csum
 170  *
 171  * PURPOSE:     To generate the checksum of the packet in the mbuf chain (m).
 172  *              The first of the 2 (logically) adjacent checksum bytes
 173  *              (x and y) go at offset (n).
 174  *              (n) is an offset relative to the beginning of the data,
 175  *              not the beginning of the mbuf.
 176  *              (l) is the length of the total mbuf chain's data.
 177  *              Called from tp_emit(), tp_error_emit()
 178  *              clnp_emit_er(), clnp_forward(), clnp_output().
 179  *
 180  * RETURNS:     Rien
 181  *
 182  * SIDE EFFECTS: Puts the 2 checksum bytes into the packet.
 183  *
 184  * NOTES:       Ditto the note for iso_check_csum().
 185  */
 186
 187 void
 188 iso_gen_csum(
 189         struct mbuf    *m,
 190         int             n,      /* offset of 2 checksum bytes */
 191         int             l)
 192 {
 193         u_char *p = mtod(m, u_char *);
 194         int    c0 = 0, c1 = 0;
 195         int    i = 0;
 196         int             loc = n++, len = 0;     /* n is position, loc is
 197                                                  * offset */
 198         u_char         *xloc = NULL;
 199         u_char         *yloc = NULL;
 200         int             cum = 0;/* cum == cumulative length */
 201
 202 #ifdef ARGO_DEBUG
 203         if (argo_debug[D_CHKSUM]) {
 204                 printf("enter gen csum m %p n 0x%x l 0x%x\n",
 205                     m, n - 1, l);
 206         }
 207 #endif
 208
 209         while (i < l) {
 210                 len = min(m->m_len, PAGE_SIZE);
 211                 /* RAH: don't cksum more than l bytes */
 212                 len = min(len, l - i);
 213
 214                 cum += len;
 215                 p = mtod(m, u_char *);
 216
 217                 if (loc >= 0) {
 218                         if (loc < len) {
 219                                 xloc = loc + mtod(m, u_char *);
 220 #ifdef ARGO_DEBUG
 221                                 if (argo_debug[D_CHKSUM]) {
 222                                         printf("1: zeroing xloc %p loc 0x%x\n",
 223                                             xloc, loc);
 224                                 }
 225 #endif
 226                                 *xloc = (u_char) 0;
 227                                 if (loc + 1 < len) {
 228                                         /*
 229                                          * both xloc and yloc are in same
 230                                          * mbuf
 231                                          */
 232                                         yloc = 1 + xloc;
 233 #ifdef ARGO_DEBUG
 234                                         if (argo_debug[D_CHKSUM]) {
 235                                                 printf(
 236                                         "2: zeroing yloc %p loc 0x%x\n",
 237                                         yloc, loc);
 238                                         }
 239 #endif
 240                                         *yloc = (u_char) 0;
 241                                 } else {
 242                                         /* crosses boundary of mbufs */
 243                                         yloc = mtod(m->m_next, u_char *);
 244 #ifdef ARGO_DEBUG
 245                                         if (argo_debug[D_CHKSUM]) {
 246                                                 printf(
 247                                             "3: zeroing yloc %p \n", yloc);
 248                                         }
 249 #endif
 250                                         *yloc = (u_char) 0;
 251                                 }
 252                         }
 253                         loc -= len;
 254                 }
 255                 while (i < cum) {
 256                         c0 = (c0 + *p);
 257                         c1 += c0;
 258                         i++;
 259                         p++;
 260                 }
 261                 m = m->m_next;
 262         }
 263 #ifdef ARGO_DEBUG
 264         if (argo_debug[D_CHKSUM]) {
 265                 printf("gen csum final xloc %p yloc %p\n", xloc, yloc);
 266         }
 267 #endif
 268
 269         c1 = (((c0 * (l - n)) - c1) % 255);
 270         if (xloc)
 271                 *xloc = (u_char) ((c1 < 0) ? c1 + 255 : c1);
 272
 273         c1 = (-(int) (c1 + c0)) % 255;
 274         if (yloc)
 275                 *yloc = (u_char) (c1 < 0 ? c1 + 255 : c1);
 276
 277 #ifdef ARGO_DEBUG
 278         if (argo_debug[D_CHKSUM]) {
 279                 printf("gen csum end \n");
 280         }
 281 #endif
 282 }
 283
 284 /*
 285  * FUNCTION:    m_datalen
 286  *
 287  * PURPOSE:     returns length of the mbuf chain.
 288  *              used all over the iso code.
 289  *
 290  * RETURNS:     integer
 291  *
 292  * SIDE EFFECTS: none
 293  *
 294  * NOTES:
 295  */
 296
 297 int
 298 m_datalen(struct mbuf *m)
 299 {
 300         int    datalen;
 301
 302         for (datalen = 0; m; m = m->m_next)
 303                 datalen += m->m_len;
 304         return datalen;
 305 }
 306
 307 int
 308 m_compress(struct mbuf *in, struct mbuf **out)
 309 {
 310         int    datalen = 0;
 311         int             s = splnet();
 312
 313         if (in->m_next == NULL) {
 314                 *out = in;
 315 #ifdef ARGO_DEBUG
 316                 if (argo_debug[D_REQUEST]) {
 317                         printf("m_compress returning 0x%x: A\n", in->m_len);
 318                 }
 319 #endif
 320                 splx(s);
 321                 return in->m_len;
 322         }
 323         MGET((*out), M_DONTWAIT, MT_DATA);
 324         if ((*out) == NULL) {
 325                 *out = in;
 326 #ifdef ARGO_DEBUG
 327                 if (argo_debug[D_REQUEST]) {
 328                         printf("m_compress returning -1: B\n");
 329                 }
 330 #endif
 331                 splx(s);
 332                 return -1;
 333         }
 334         (*out)->m_len = 0;
 335         (*out)->m_nextpkt = NULL;
 336
 337         while (in) {
 338 #ifdef ARGO_DEBUG
 339                 if (argo_debug[D_REQUEST]) {
 340                         printf("m_compress in %p *out %p\n", in, *out);
 341                         printf("m_compress in: len 0x%x, off %p\n",
 342                             in->m_len, in->m_data);
 343                         printf("m_compress *out: len 0x%x, off %p\n",
 344                             (*out)->m_len, (*out)->m_data);
 345                 }
 346 #endif
 347                 if (in->m_flags & M_EXT) {
 348                         ASSERT(in->m_len == 0);
 349                 }
 350                 if (in->m_len == 0) {
 351                         in = in->m_next;
 352                         continue;
 353                 }
 354                 if (((*out)->m_flags & M_EXT) == 0) {
 355                         int             len;
 356
 357                         len = M_TRAILINGSPACE(*out);
 358                         len = min(len, in->m_len);
 359                         datalen += len;
 360
 361 #ifdef ARGO_DEBUG
 362                         if (argo_debug[D_REQUEST]) {
 363                                 printf("m_compress copying len %d\n", len);
 364                         }
 365 #endif
 366                         memcpy(mtod((*out), char *) + (*out)->m_len,
 367                             mtod(in, void *), (unsigned) len);
 368
 369                         (*out)->m_len += len;
 370                         in->m_len -= len;
 371                         continue;
 372                 } else {
 373                         /* (*out) is full */
 374                         if (((*out)->m_next = m_get(M_DONTWAIT, MT_DATA)) == NULL) {
 375                                 m_freem(*out);
 376                                 *out = in;
 377 #ifdef ARGO_DEBUG
 378                                 if (argo_debug[D_REQUEST]) {
 379                                         printf("m_compress returning -1: B\n");
 380                                 }
 381 #endif
 382                                 splx(s);
 383                                 return -1;
 384                         }
 385                         (*out)->m_len = 0;
 386                         (*out)->m_nextpkt = NULL;
 387                         *out = (*out)->m_next;
 388                 }
 389         }
 390         m_freem(in);
 391 #ifdef ARGO_DEBUG
 392         if (argo_debug[D_REQUEST]) {
 393                 printf("m_compress returning 0x%x: A\n", datalen);
 394         }
 395 #endif
 396         splx(s);
 397         return datalen;
 398 }