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

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 2001-2007, by Cisco Systems, Inc. All rights reserved.
      * Copyright (c) 2008-2012, by Randall Stewart. All rights reserved.
      * Copyright (c) 2008-2012, by Michael Tuexen. All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions are met:
     *
     * a) Redistributions of source code must retain the above copyright notice,
     *   this list of conditions and the following disclaimer.
     *
     * b) Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in
     *   the documentation and/or other materials provided with the distribution.
     *
     * c) Neither the name of Cisco Systems, Inc. nor the names of its
     *    contributors may be used to endorse or promote products derived
     *    from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
     * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
     * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
     * THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_sctp.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/gsb_crc32.h>
    #include <sys/mbuf.h>
    
    #include <netinet/sctp.h>
    #include <netinet/sctp_crc32.h>
    #if defined(SCTP) || defined(SCTP_SUPPORT)
    #include <netinet/sctp_os.h>
    #include <netinet/sctp_pcb.h>
    #endif
    
    static uint32_t
    sctp_finalize_crc32c(uint32_t crc32c)
    {
    #if BYTE_ORDER == BIG_ENDIAN
            uint32_t byte0, byte1, byte2, byte3;
    #endif
    
    #if BYTE_ORDER == BIG_ENDIAN
            /*
             * For BIG-ENDIAN platforms, the result is in LITTLE-ENDIAN byte
             * order. For LITTLE-ENDIAN platforms, the result is in in
             * BIG-ENDIAN byte order. So for BIG-ENDIAN platforms the bytes must
             * be swapped to return the result always in network byte order (aka
             * BIG-ENDIAN).
             */
            byte0 = crc32c & 0x000000ff;
            byte1 = (crc32c >> 8) & 0x000000ff;
            byte2 = (crc32c >> 16) & 0x000000ff;
            byte3 = (crc32c >> 24) & 0x000000ff;
            crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
    #endif
            return (~crc32c);
    }
    
    static int
    sctp_calculate_cksum_cb(void *arg, void *data, u_int len)
    {
            uint32_t *basep;
    
            basep = arg;
            *basep = calculate_crc32c(*basep, data, len);
            return (0);
    }
    
    /*
     * Compute the SCTP checksum in network byte order for a given mbuf chain m
     * which contains an SCTP packet starting at offset.
     * Since this function is also called by ipfw, don't assume that
     * it is compiled on a kernel with SCTP support.
     */
    uint32_t
    sctp_calculate_cksum(struct mbuf *m, int32_t offset)
    {
            uint32_t base;
            int len;
    
            M_ASSERTPKTHDR(m);
            KASSERT(offset < m->m_pkthdr.len,
               ("%s: invalid offset %u into mbuf %p", __func__, offset, m));
   
           base = 0xffffffff;
           len = m->m_pkthdr.len - offset;
           (void)m_apply(m, offset, len, sctp_calculate_cksum_cb, &base);
           return (sctp_finalize_crc32c(base));
   }
   
   #if defined(SCTP) || defined(SCTP_SUPPORT)
   
   VNET_DEFINE(struct sctp_base_info, system_base_info);
   
   /*
    * Compute and insert the SCTP checksum in network byte order for a given
    * mbuf chain m which contains an SCTP packet starting at offset.
    */
   void
   sctp_delayed_cksum(struct mbuf *m, uint32_t offset)
   {
           uint32_t checksum;
   
           checksum = sctp_calculate_cksum(m, offset);
           SCTP_STAT_DECR(sctps_sendhwcrc);
           SCTP_STAT_INCR(sctps_sendswcrc);
           offset += offsetof(struct sctphdr, checksum);
   
           if (offset + sizeof(uint32_t) > (uint32_t)(m->m_pkthdr.len)) {
   #ifdef INVARIANTS
                   panic("sctp_delayed_cksum(): m->m_pkthdr.len: %d, offset: %u.",
                       m->m_pkthdr.len, offset);
   #else
                   SCTP_PRINTF("sctp_delayed_cksum(): m->m_pkthdr.len: %d, offset: %u.\n",
                       m->m_pkthdr.len, offset);
   #endif
                   return;
           }
           m_copyback(m, (int)offset, (int)sizeof(uint32_t), (caddr_t)&checksum);
   }
   #endif

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