include/net/sctp/checksum.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /* SCTP kernel reference Implementation
   3  * Copyright (c) 1999-2001 Motorola, Inc.
   4  * Copyright (c) 2001-2003 International Business Machines, Corp.
   5  *
   6  * This file is part of the SCTP kernel reference Implementation
   7  *
   8  * SCTP Checksum functions
   9  *
  10  * Please send any bug reports or fixes you make to the
  11  * email address(es):
  12  *    lksctp developers <linux-sctp@vger.kernel.org>
  13  *
  14  * Written or modified by:
  15  *    Dinakaran Joseph
  16  *    Jon Grimm <jgrimm@us.ibm.com>
  17  *    Sridhar Samudrala <sri@us.ibm.com>
  18  *
  19  * Rewritten to use libcrc32c by:
  20  *    Vlad Yasevich <vladislav.yasevich@hp.com>
  21  */
  22
  23 #ifndef __sctp_checksum_h__
  24 #define __sctp_checksum_h__
  25
  26 #include <linux/types.h>
  27 #include <net/sctp/sctp.h>
  28 #include <linux/crc32c.h>
  29 #include <linux/crc32.h>
  30
  31 static inline __wsum sctp_csum_update(const void *buff, int len, __wsum sum)
  32 {
  33         /* This uses the crypto implementation of crc32c, which is either
  34          * implemented w/ hardware support or resolves to __crc32c_le().
  35          */
  36         return (__force __wsum)crc32c((__force __u32)sum, buff, len);
  37 }
  38
  39 static inline __wsum sctp_csum_combine(__wsum csum, __wsum csum2,
  40                                        int offset, int len)
  41 {
  42         return (__force __wsum)__crc32c_le_combine((__force __u32)csum,
  43                                                    (__force __u32)csum2, len);
  44 }
  45
  46 static const struct skb_checksum_ops sctp_csum_ops = {
  47         .update  = sctp_csum_update,
  48         .combine = sctp_csum_combine,
  49 };
  50
  51 static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
  52                                         unsigned int offset)
  53 {
  54         struct sctphdr *sh = (struct sctphdr *)(skb->data + offset);
  55         __le32 old = sh->checksum;
  56         __wsum new;
  57
  58         sh->checksum = 0;
  59         new = ~__skb_checksum(skb, offset, skb->len - offset, ~(__wsum)0,
  60                               &sctp_csum_ops);
  61         sh->checksum = old;
  62
  63         return cpu_to_le32((__force __u32)new);
  64 }
  65
  66 #endif /* __sctp_checksum_h__ */