1/*-
2 * Copyright (c) 2001-2007, by Cisco Systems, Inc. All rights reserved.
3 * Copyright (c) 2008-2012, by Randall Stewart. All rights reserved.
4 * Copyright (c) 2008-2012, by Michael Tuexen. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * a) Redistributions of source code must retain the above copyright notice,
10 *   this list of conditions and the following disclaimer.
11 *
12 * b) Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in
14 *   the documentation and/or other materials provided with the distribution.
15 *
16 * c) Neither the name of Cisco Systems, Inc. nor the names of its
17 *    contributors may be used to endorse or promote products derived
18 *    from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
22 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
30 * THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD: stable/11/sys/netinet/sctp_crc32.c 332229 2018-04-07 20:27:11Z tuexen $");
35
36#include "opt_sctp.h"
37
38#ifdef SCTP
39#include <netinet/sctp_os.h>
40#include <netinet/sctp.h>
41#include <netinet/sctp_crc32.h>
42#include <netinet/sctp_pcb.h>
43#else
44#include <sys/param.h>
45#include <sys/systm.h>
46#include <sys/mbuf.h>
47
48#include <netinet/sctp_crc32.h>
49#endif
50
51static uint32_t
52sctp_finalize_crc32c(uint32_t crc32c)
53{
54	uint32_t result;
55#if BYTE_ORDER == BIG_ENDIAN
56	uint8_t byte0, byte1, byte2, byte3;
57#endif
58
59	/* Complement the result */
60	result = ~crc32c;
61#if BYTE_ORDER == BIG_ENDIAN
62	/*
63	 * For BIG-ENDIAN platforms the result is in little-endian form. So
64	 * we must swap the bytes to return the result in network byte
65	 * order.
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 LITTLE ENDIAN platforms the result is in already in network
75	 * byte order.
76	 */
77	crc32c = result;
78#endif
79	return (crc32c);
80}
81
82/*
83 * Compute the SCTP checksum in network byte order for a given mbuf chain m
84 * which contains an SCTP packet starting at offset.
85 * Since this function is also called by ipfw, don't assume that
86 * it is compiled on a kernel with SCTP support.
87 */
88uint32_t
89sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
90{
91	uint32_t base = 0xffffffff;
92
93	while (offset > 0) {
94		KASSERT(m != NULL, ("sctp_calculate_cksum, offset > length of mbuf chain"));
95		if (offset < (uint32_t)m->m_len) {
96			break;
97		}
98		offset -= m->m_len;
99		m = m->m_next;
100	}
101	if (offset > 0) {
102		base = calculate_crc32c(base,
103		    (unsigned char *)(m->m_data + offset),
104		    (unsigned int)(m->m_len - offset));
105		m = m->m_next;
106	}
107	while (m != NULL) {
108		base = calculate_crc32c(base,
109		    (unsigned char *)m->m_data,
110		    (unsigned int)m->m_len);
111		m = m->m_next;
112	}
113	base = sctp_finalize_crc32c(base);
114	return (base);
115}
116
117#ifdef SCTP
118/*
119 * Compute and insert the SCTP checksum in network byte order for a given
120 * mbuf chain m which contains an SCTP packet starting at offset.
121 */
122void
123sctp_delayed_cksum(struct mbuf *m, uint32_t offset)
124{
125	uint32_t checksum;
126
127	checksum = sctp_calculate_cksum(m, offset);
128	SCTP_STAT_DECR(sctps_sendhwcrc);
129	SCTP_STAT_INCR(sctps_sendswcrc);
130	offset += offsetof(struct sctphdr, checksum);
131
132	if (offset + sizeof(uint32_t) > (uint32_t)(m->m_len)) {
133#ifdef INVARIANTS
134		panic("sctp_delayed_cksum(): m->m_len: %d, offset: %u.",
135		    m->m_len, offset);
136#else
137		SCTP_PRINTF("sctp_delayed_cksum(): m->m_len: %d, offset: %u.\n",
138		    m->m_len, offset);
139#endif
140		return;
141	}
142	*(uint32_t *)(m->m_data + offset) = checksum;
143}
144#endif
145