1/* $NetBSD: in_cksum.c,v 1.7 1997/09/02 13:18:15 thorpej Exp $ */
2
3/*-
4 * SPDX-License-Identifier: BSD-4-Clause
5 *
6 * Copyright (c) 1988, 1992, 1993
7 *	The Regents of the University of California.  All rights reserved.
8 * Copyright (c) 1996
9 *	Matt Thomas <matt@3am-software.com>
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 *    must display the following acknowledgement:
21 *	This product includes software developed by the University of
22 *	California, Berkeley and its contributors.
23 * 4. Neither the name of the University nor the names of its contributors
24 *    may be used to endorse or promote products derived from this software
25 *    without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 */
39
40#include <sys/cdefs.h>			/* RCS ID & Copyright macro defns */
41#include <sys/param.h>
42#include <sys/mbuf.h>
43#include <sys/systm.h>
44#include <netinet/in_systm.h>
45#include <netinet/in.h>
46#include <netinet/ip.h>
47#include <machine/in_cksum.h>
48
49/*
50 * Checksum routine for Internet Protocol family headers
51 *    (Portable Alpha version).
52 *
53 * This routine is very heavily used in the network
54 * code and should be modified for each CPU to be as fast as possible.
55 */
56
57#define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
58#define REDUCE32							  \
59    {									  \
60	q_util.q = sum;							  \
61	sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];	  \
62    }
63#define REDUCE16							  \
64    {									  \
65	q_util.q = sum;							  \
66	l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
67	sum = l_util.s[0] + l_util.s[1];				  \
68	ADDCARRY(sum);							  \
69    }
70
71union l_util {
72	u_int16_t s[2];
73	u_int32_t l;
74};
75union q_util {
76	u_int16_t s[4];
77	u_int32_t l[2];
78	u_int64_t q;
79};
80
81u_short
82in_addword(u_short a, u_short b)
83{
84	u_int64_t sum = a + b;
85
86	ADDCARRY(sum);
87	return (sum);
88}
89
90static
91uint64_t _do_cksum(void *addr, int len)
92{
93	uint64_t sum;
94	union q_util q_util;
95
96	sum = do_cksum(addr, len);
97	REDUCE32;
98	return (sum);
99}
100
101u_short
102in_cksum_skip(struct mbuf *m, int len, int skip)
103{
104	u_int64_t sum = 0;
105	int mlen = 0;
106	int clen = 0;
107	caddr_t addr;
108	union q_util q_util;
109	union l_util l_util;
110
111        len -= skip;
112        for (; skip && m; m = m->m_next) {
113                if (m->m_len > skip) {
114                        mlen = m->m_len - skip;
115			addr = mtod(m, caddr_t) + skip;
116                        goto skip_start;
117                } else {
118                        skip -= m->m_len;
119                }
120        }
121
122	for (; m && len; m = m->m_next) {
123		if (m->m_len == 0)
124			continue;
125		mlen = m->m_len;
126		addr = mtod(m, caddr_t);
127skip_start:
128		if (len < mlen)
129			mlen = len;
130
131		if ((clen ^ (int) addr) & 1)
132		    sum += _do_cksum(addr, mlen) << 8;
133		else
134		    sum += _do_cksum(addr, mlen);
135
136		clen += mlen;
137		len -= mlen;
138	}
139	REDUCE16;
140	return (~sum & 0xffff);
141}
142
143u_int in_cksum_hdr(const struct ip *ip)
144{
145	u_int64_t sum = do_cksum(ip, sizeof(struct ip));
146	union q_util q_util;
147    	union l_util l_util;
148	REDUCE16;
149	return (~sum & 0xffff);
150}
151