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
  46 static 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 (__force __wsum)crc32c((__force __u32)sum, buff, len);
  52 }
  53
  54 static inline __wsum sctp_csum_combine(__wsum csum, __wsum csum2,
  55                                        int offset, int len)
  56 {
  57         return (__force __wsum)__crc32c_le_combine((__force __u32)csum,
  58                                                    (__force __u32)csum2, len);
  59 }
  60
  61 static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
  62                                         unsigned int offset)
  63 {
  64         struct sctphdr *sh = sctp_hdr(skb);
  65         const struct skb_checksum_ops ops = {
  66                 .update  = sctp_csum_update,
  67                 .combine = sctp_csum_combine,
  68         };
  69         __le32 old = sh->checksum;
  70         __wsum new;
  71
  72         sh->checksum = 0;
  73         new = ~__skb_checksum(skb, offset, skb->len - offset, ~(__wsum)0, &ops);
  74         sh->checksum = old;
  75
  76         return cpu_to_le32((__force __u32)new);
  77 }
  78
  79 #endif /* __sctp_checksum_h__ */