xref: /openbmc/linux/include/net/sctp/checksum.h (revision 22246614)
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 }
79