LXR linux/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, see
  23 * <http://www.gnu.org/licenses/>.
  24 *
  25 * Please send any bug reports or fixes you make to the
  26 * email address(es):
  27 *    lksctp developers <linux-sctp@vger.kernel.org>
  28 *
  29 * Written or modified by:
  30 *    Dinakaran Joseph
  31 *    Jon Grimm <jgrimm@us.ibm.com>
  32 *    Sridhar Samudrala <sri@us.ibm.com>
  33 *
  34 * Rewritten to use libcrc32c by:
  35 *    Vlad Yasevich <vladislav.yasevich@hp.com>
  36 */
  37
  38#ifndef __sctp_checksum_h__
  39#define __sctp_checksum_h__
  40
  41#include <linux/types.h>
  42#include <net/sctp/sctp.h>
  43#include <linux/crc32c.h>
  44#include <linux/crc32.h>
  45
  46static inline __wsum sctp_csum_update(const void *buff, int len, __wsum sum)
  47{
  48        /* This uses the crypto implementation of crc32c, which is either
  49         * implemented w/ hardware support or resolves to __crc32c_le().
  50         */
  51        return crc32c(sum, buff, len);
  52}
  53
  54static inline __wsum sctp_csum_combine(__wsum csum, __wsum csum2,
  55                                       int offset, int len)
  56{
  57        return __crc32c_le_combine(csum, csum2, len);
  58}
  59
  60static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
  61                                        unsigned int offset)
  62{
  63        struct sctphdr *sh = sctp_hdr(skb);
  64        __le32 ret, old = sh->checksum;
  65        const struct skb_checksum_ops ops = {
  66                .update  = sctp_csum_update,
  67                .combine = sctp_csum_combine,
  68        };
  69
  70        sh->checksum = 0;
  71        ret = cpu_to_le32(~__skb_checksum(skb, offset, skb->len - offset,
  72                                          ~(__u32)0, &ops));
  73        sh->checksum = old;
  74
  75        return ret;
  76}
  77
  78#endif /* __sctp_checksum_h__ */
  79