/* SCTP kernel reference Implementation
* Copyright (c) 1999-2001 Motorola, Inc.
* Copyright (c) 2001-2003 International Business Machines, Corp.
*
* This file is part of the SCTP kernel reference Implementation
*
* SCTP Checksum functions
*
* The SCTP reference implementation is free software;
* you can redistribute it and/or modify it under the terms of
* the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* The SCTP reference implementation is distributed in the hope that it
* will be useful, but WITHOUT ANY WARRANTY; without even the implied
* ************************
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU CC; see the file COPYING. If not, write to
* the Free Software Foundation, 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
* Please send any bug reports or fixes you make to the
* email address(es):
* lksctp developers <linux-sctp@vger.kernel.org>
*
* Written or modified by:
* Dinakaran Joseph
* Jon Grimm <jgrimm@us.ibm.com>
* Sridhar Samudrala <sri@us.ibm.com>
*
* Rewritten to use libcrc32c by:
* Vlad Yasevich <vladislav.yasevich@hp.com>
*/
#ifndef __sctp_checksum_h__
#define __sctp_checksum_h__
#include <linux/types.h>
#include <net/sctp/sctp.h>
#include <linux/crc32c.h>
static inline __u32 sctp_crc32c(__u32 crc, u8 *buffer, u16 length)
{
return crc32c(crc, buffer, length);
}
static inline __u32 sctp_start_cksum(__u8 *buffer, __u16 length)
{
__u32 crc = ~(__u32)0;
__u8 zero[sizeof(__u32)] = {0};
/* Optimize this routine to be SCTP specific, knowing how
* to skip the checksum field of the SCTP header.
*/
/* Calculate CRC up to the checksum. */
crc = sctp_crc32c(crc, buffer, sizeof(struct sctphdr) - sizeof(__u32));
/* Skip checksum field of the header. */
crc = sctp_crc32c(crc, zero, sizeof(__u32));
/* Calculate the rest of the CRC. */
crc = sctp_crc32c(crc, &buffer[sizeof(struct sctphdr)],
length - sizeof(struct sctphdr));
return crc;
}
static inline __u32 sctp_update_cksum(__u8 *buffer, __u16 length, __u32 crc32)
{
return sctp_crc32c(crc32, buffer, length);
}
static inline __le32 sctp_end_cksum(__u32 crc32)
{
return cpu_to_le32(~crc32);
}
/* Calculate the CRC32C checksum of an SCTP packet. */
static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
unsigned int offset)
{
const struct sk_buff *iter;
__u32 crc32 = sctp_start_cksum(skb->data + offset,
skb_headlen(skb) - offset);
skb_walk_frags(skb, iter)
crc32 = sctp_update_cksum((__u8 *) iter->data,
skb_headlen(iter), crc32);
return sctp_end_cksum(crc32);
}
#endif /* __sctp_checksum_h__ */
