include/net/sctp/checksum.h

   1 /* SCTP kernel reference Implementation
   2  * Copyright (c) 1999-2001 Motorola, Inc.
   3  * Copyright (c) 2001-2003 International Business Machines, Corp.
   4  *
   5  * This file is part of the SCTP kernel reference Implementation
   6  *
   7  * SCTP Checksum functions
   8  *
   9  * The SCTP reference implementation is free software;
  10  * you can redistribute it and/or modify it under the terms of
  11  * the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2, or (at your option)
  13  * any later version.
  14  *
  15  * The SCTP reference implementation is distributed in the hope that it
  16  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  17  *                 ************************
  18  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  19  * See the GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with GNU CC; see the file COPYING.  If not, write to
  23  * the Free Software Foundation, 59 Temple Place - Suite 330,
  24  * Boston, MA 02111-1307, USA.
  25  *
  26  * Please send any bug reports or fixes you make to the
  27  * email address(es):
  28  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  29  *
  30  * Or submit a bug report through the following website:
  31  *    http://www.sf.net/projects/lksctp
  32  *
  33  * Written or modified by:
  34  *    Dinakaran Joseph
  35  *    Jon Grimm <jgrimm@us.ibm.com>
  36  *    Sridhar Samudrala <sri@us.ibm.com>
  37  *
  38  * Rewritten to use libcrc32c by:
  39  *    Vlad Yasevich <vladislav.yasevich@hp.com>
  40  *
  41  * Any bugs reported given to us we will try to fix... any fixes shared will
  42  * be incorporated into the next SCTP release.
  43  */
  44
  45 #include <linux/types.h>
  46 #include <net/sctp/sctp.h>
  47 #include <linux/crc32c.h>
  48
  49 static inline __u32 sctp_start_cksum(__u8 *buffer, __u16 length)
  50 {
  51         __u32 crc = ~(__u32) 0;
  52         __u8  zero[sizeof(__u32)] = {0};
  53
  54         /* Optimize this routine to be SCTP specific, knowing how
  55          * to skip the checksum field of the SCTP header.
  56          */
  57
  58         /* Calculate CRC up to the checksum. */
  59         crc = crc32c(crc, buffer, sizeof(struct sctphdr) - sizeof(__u32));
  60
  61         /* Skip checksum field of the header. */
  62         crc = crc32c(crc, zero, sizeof(__u32));
  63
  64         /* Calculate the rest of the CRC. */
  65         crc = crc32c(crc, &buffer[sizeof(struct sctphdr)],
  66                             length - sizeof(struct sctphdr));
  67         return crc;
  68 }
  69
  70 static inline __u32 sctp_update_cksum(__u8 *buffer, __u16 length, __u32 crc32)
  71 {
  72         return crc32c(crc32, buffer, length);
  73 }
  74
  75 static inline __u32 sctp_end_cksum(__u32 crc32)
  76 {
  77         return ntohl(~crc32);
  78 }