The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netinet/sctp_crc32.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 2001-2007, by Cisco Systems, Inc. All rights reserved.
    5  * Copyright (c) 2008-2012, by Randall Stewart. All rights reserved.
    6  * Copyright (c) 2008-2012, by Michael Tuexen. 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 are met:
   10  *
   11  * a) Redistributions of source code must retain the above copyright notice,
   12  *   this list of conditions and the following disclaimer.
   13  *
   14  * b) Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in
   16  *   the documentation and/or other materials provided with the distribution.
   17  *
   18  * c) Neither the name of Cisco Systems, Inc. nor the names of its
   19  *    contributors may be used to endorse or promote products derived
   20  *    from this software without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   23  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
   24  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   26  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   27  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   28  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   29  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   30  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   31  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
   32  * THE POSSIBILITY OF SUCH DAMAGE.
   33  */
   34 
   35 #include <sys/cdefs.h>
   36 __FBSDID("$FreeBSD: releng/12.0/sys/netinet/sctp_crc32.c 336508 2018-07-19 20:11:14Z tuexen $");
   37 
   38 #include "opt_sctp.h"
   39 
   40 #ifdef SCTP
   41 #include <netinet/sctp_os.h>
   42 #include <netinet/sctp.h>
   43 #include <netinet/sctp_crc32.h>
   44 #include <netinet/sctp_pcb.h>
   45 #else
   46 #include <sys/param.h>
   47 #include <sys/systm.h>
   48 #include <sys/mbuf.h>
   49 
   50 #include <netinet/sctp_crc32.h>
   51 #endif
   52 
   53 static uint32_t
   54 sctp_finalize_crc32c(uint32_t crc32c)
   55 {
   56         uint32_t result;
   57 #if BYTE_ORDER == BIG_ENDIAN
   58         uint8_t byte0, byte1, byte2, byte3;
   59 #endif
   60 
   61         /* Complement the result */
   62         result = ~crc32c;
   63 #if BYTE_ORDER == BIG_ENDIAN
   64         /*
   65          * For BIG-ENDIAN platforms the result is in little-endian form. So
   66          * we must swap the bytes to return the result in network byte
   67          * order.
   68          */
   69         byte0 = result & 0x000000ff;
   70         byte1 = (result >> 8) & 0x000000ff;
   71         byte2 = (result >> 16) & 0x000000ff;
   72         byte3 = (result >> 24) & 0x000000ff;
   73         crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
   74 #else
   75         /*
   76          * For LITTLE ENDIAN platforms the result is in already in network
   77          * byte order.
   78          */
   79         crc32c = result;
   80 #endif
   81         return (crc32c);
   82 }
   83 
   84 /*
   85  * Compute the SCTP checksum in network byte order for a given mbuf chain m
   86  * which contains an SCTP packet starting at offset.
   87  * Since this function is also called by ipfw, don't assume that
   88  * it is compiled on a kernel with SCTP support.
   89  */
   90 uint32_t
   91 sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
   92 {
   93         uint32_t base = 0xffffffff;
   94 
   95         while (offset > 0) {
   96                 KASSERT(m != NULL, ("sctp_calculate_cksum, offset > length of mbuf chain"));
   97                 if (offset < (uint32_t)m->m_len) {
   98                         break;
   99                 }
  100                 offset -= m->m_len;
  101                 m = m->m_next;
  102         }
  103         if (offset > 0) {
  104                 base = calculate_crc32c(base,
  105                     (unsigned char *)(m->m_data + offset),
  106                     (unsigned int)(m->m_len - offset));
  107                 m = m->m_next;
  108         }
  109         while (m != NULL) {
  110                 base = calculate_crc32c(base,
  111                     (unsigned char *)m->m_data,
  112                     (unsigned int)m->m_len);
  113                 m = m->m_next;
  114         }
  115         base = sctp_finalize_crc32c(base);
  116         return (base);
  117 }
  118 
  119 #ifdef SCTP
  120 /*
  121  * Compute and insert the SCTP checksum in network byte order for a given
  122  * mbuf chain m which contains an SCTP packet starting at offset.
  123  */
  124 void
  125 sctp_delayed_cksum(struct mbuf *m, uint32_t offset)
  126 {
  127         uint32_t checksum;
  128 
  129         checksum = sctp_calculate_cksum(m, offset);
  130         SCTP_STAT_DECR(sctps_sendhwcrc);
  131         SCTP_STAT_INCR(sctps_sendswcrc);
  132         offset += offsetof(struct sctphdr, checksum);
  133 
  134         if (offset + sizeof(uint32_t) > (uint32_t)(m->m_len)) {
  135 #ifdef INVARIANTS
  136                 panic("sctp_delayed_cksum(): m->m_len: %d, offset: %u.",
  137                     m->m_len, offset);
  138 #else
  139                 SCTP_PRINTF("sctp_delayed_cksum(): m->m_len: %d, offset: %u.\n",
  140                     m->m_len, offset);
  141 #endif
  142                 return;
  143         }
  144         *(uint32_t *)(m->m_data + offset) = checksum;
  145 }
  146 #endif

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