sctp_crc32.c revision 188605 
1/*-
2 * Copyright (c) 2001-2007, by Cisco Systems, Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are met:
6 *
7 * a) Redistributions of source code must retain the above copyright notice,
8 *   this list of conditions and the following disclaimer.
9 *
10 * b) Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *   the documentation and/or other materials provided with the distribution.
13 *
14 * c) Neither the name of Cisco Systems, Inc. nor the names of its
15 *    contributors may be used to endorse or promote products derived
16 *    from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
20 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
28 * THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31/* $KAME: sctp_crc32.c,v 1.12 2005/03/06 16:04:17 itojun Exp $	 */
32
33
34#include <sys/cdefs.h>
35__FBSDID("$FreeBSD: head/sys/netinet/sctp_crc32.c 188605 2009-02-14 11:34:57Z rrs $");
36
37#include <sys/types.h>
38#include <sys/socket.h>
39#include <sys/socketvar.h>
40#include <sys/uio.h>
41#include <sys/libkern.h>
42#include <netinet/sctp.h>
43#include <netinet/sctp_os.h>
44#include <netinet/sctp_crc32.h>
45#include <netinet/sctp_pcb.h>
46
47
48#if !defined(SCTP_WITH_NO_CSUM)
49
50static uint32_t
51sctp_finalize_crc32c(uint32_t crc32c)
52{
53	uint32_t result;
54
55#if BYTE_ORDER == BIG_ENDIAN
56	uint8_t byte0, byte1, byte2, byte3;
57
58#endif
59	/* Complement the result */
60	result = ~crc32c;
61#if BYTE_ORDER == BIG_ENDIAN
62	/*
63	 * For BIG-ENDIAN.. aka Motorola byte order the result is in
64	 * little-endian form. So we must manually swap the bytes. Then we
65	 * can call htonl() which does nothing...
66	 */
67	byte0 = result & 0x000000ff;
68	byte1 = (result >> 8) & 0x000000ff;
69	byte2 = (result >> 16) & 0x000000ff;
70	byte3 = (result >> 24) & 0x000000ff;
71	crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
72#else
73	/*
74	 * For INTEL platforms the result comes out in network order. No
75	 * htonl is required or the swap above. So we optimize out both the
76	 * htonl and the manual swap above.
77	 */
78	crc32c = result;
79#endif
80	return (crc32c);
81}
82
83uint32_t
84sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
85{
86	/*
87	 * given a mbuf chain with a packetheader offset by 'offset'
88	 * pointing at a sctphdr (with csum set to 0) go through the chain
89	 * of SCTP_BUF_NEXT()'s and calculate the SCTP checksum. This also
90	 * has a side bonus as it will calculate the total length of the
91	 * mbuf chain. Note: if offset is greater than the total mbuf
92	 * length, checksum=1, pktlen=0 is returned (ie. no real error code)
93	 */
94	uint32_t base = 0xffffffff;
95	struct mbuf *at;
96
97	at = m;
98	/* find the correct mbuf and offset into mbuf */
99	while ((at != NULL) && (offset > (uint32_t) SCTP_BUF_LEN(at))) {
100		offset -= SCTP_BUF_LEN(at);	/* update remaining offset
101						 * left */
102		at = SCTP_BUF_NEXT(at);
103	}
104	while (at != NULL) {
105		if ((SCTP_BUF_LEN(at) - offset) > 0) {
106			base = calculate_crc32c(base,
107			    (unsigned char *)(SCTP_BUF_AT(at, offset)),
108			    (unsigned int)(SCTP_BUF_LEN(at) - offset));
109		}
110		if (offset) {
111			/* we only offset once into the first mbuf */
112			if (offset < (uint32_t) SCTP_BUF_LEN(at))
113				offset = 0;
114			else
115				offset -= SCTP_BUF_LEN(at);
116		}
117		at = SCTP_BUF_NEXT(at);
118	}
119	base = sctp_finalize_crc32c(base);
120	return (base);
121}
122
123#else
124
125uint32_t
126sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
127{
128	return (0);
129}
130
131#endif				/* !defined(SCTP_WITH_NO_CSUM) */
132
133
134void
135sctp_delayed_cksum(struct mbuf *m)
136{
137	struct ip *ip;
138	uint32_t checksum;
139	uint32_t offset;
140
141	ip = mtod(m, struct ip *);
142	offset = ip->ip_hl << 2;
143	checksum = sctp_calculate_cksum(m, offset);
144	SCTP_STAT_DECR(sctps_sendhwcrc);
145	SCTP_STAT_INCR(sctps_sendswcrc);
146	offset += offsetof(struct sctphdr, checksum);
147
148	if (offset + sizeof(uint32_t) > (uint32_t) (m->m_len)) {
149		printf("delayed m_pullup, m->len: %d  off: %d  p: %d\n",
150		    (uint32_t) m->m_len, offset, ip->ip_p);
151		/*
152		 * XXX this shouldn't happen, but if it does, the correct
153		 * behavior may be to insert the checksum in the appropriate
154		 * next mbuf in the chain.
155		 */
156		return;
157	}
158	*(uint32_t *) (m->m_data + offset) = checksum;
159}
160