1 | /* $NetBSD: in6_cksum.c,v 1.28 2011/04/25 22:05:05 yamt Exp $ */ |
2 | |
3 | /*- |
4 | * Copyright (c) 2008 Joerg Sonnenberger <joerg@NetBSD.org>. |
5 | * All rights reserved. |
6 | * |
7 | * Redistribution and use in source and binary forms, with or without |
8 | * modification, are permitted provided that the following conditions |
9 | * are met: |
10 | * |
11 | * 1. Redistributions of source code must retain the above copyright |
12 | * notice, this list of conditions and the following disclaimer. |
13 | * 2. Redistributions in binary form must reproduce the above copyright |
14 | * notice, this list of conditions and the following disclaimer in |
15 | * the documentation and/or other materials provided with the |
16 | * distribution. |
17 | * |
18 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
19 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
20 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
21 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
22 | * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
23 | * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, |
24 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
25 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
26 | * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
27 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
28 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
29 | * SUCH DAMAGE. |
30 | */ |
31 | |
32 | #include <sys/cdefs.h> |
33 | __KERNEL_RCSID(0, "$NetBSD: in6_cksum.c,v 1.28 2011/04/25 22:05:05 yamt Exp $" ); |
34 | |
35 | #include <sys/param.h> |
36 | #include <sys/mbuf.h> |
37 | #include <netinet/in.h> |
38 | #include <netinet/ip6.h> |
39 | |
40 | /* |
41 | * Checksum of the IPv6 pseudo header. |
42 | * |
43 | * off is supposed to be the skipped IPv6 header, len is the payload size. |
44 | */ |
45 | |
46 | int |
47 | in6_cksum(struct mbuf *m, u_int8_t nxt, uint32_t off, uint32_t len) |
48 | { |
49 | union { |
50 | uint16_t words[16]; |
51 | struct { |
52 | struct in6_addr ip6_src; |
53 | struct in6_addr ip6_dst; |
54 | } addrs; |
55 | } u; |
56 | const struct in6_addr *in6_src; |
57 | const struct in6_addr *in6_dst; |
58 | const struct ip6_hdr *ip6; |
59 | uint32_t sum; |
60 | const uint16_t *w; |
61 | const char *cp; |
62 | |
63 | if (nxt == 0) |
64 | return cpu_in_cksum(m, len, off, 0); |
65 | |
66 | if (__predict_false(off < sizeof(struct ip6_hdr))) |
67 | panic("in6_cksum: offset too short for IPv6 header" ); |
68 | if (__predict_false(m->m_len < sizeof(struct ip6_hdr))) |
69 | panic("in6_cksum: mbuf too short for IPv6 header" ); |
70 | |
71 | /* |
72 | * Compute the equivalent of: |
73 | * struct ip6_hdr_pseudo ip6; |
74 | * |
75 | * bzero(sizeof(*ip6)); |
76 | * ip6.ip6ph_nxt = nxt; |
77 | * ip6.ip6ph_len = htonl(len); |
78 | * ipv6.ip6ph_src = mtod(m, struct ip6_hdr *)->ip6_src; |
79 | * in6_clearscope(&ip6->ip6ph_src); |
80 | * ipv6.ip6ph_dst = mtod(m, struct ip6_hdr *)->ip6_dst; |
81 | * in6_clearscope(&ip6->ip6ph_dst); |
82 | * sum = one_add(&ip6); |
83 | */ |
84 | |
85 | #if BYTE_ORDER == LITTLE_ENDIAN |
86 | sum = ((len & 0xffff) + ((len >> 16) & 0xffff) + nxt) << 8; |
87 | #else |
88 | sum = (len & 0xffff) + ((len >> 16) & 0xffff) + nxt; |
89 | #endif |
90 | cp = mtod(m, const char *); |
91 | w = (const uint16_t *)(cp + offsetof(struct ip6_hdr, ip6_src)); |
92 | ip6 = (const void *)cp; |
93 | if (__predict_true((uintptr_t)w % 2 == 0)) { |
94 | in6_src = &ip6->ip6_src; |
95 | in6_dst = &ip6->ip6_dst; |
96 | } else { |
97 | memcpy(&u, &ip6->ip6_src, 32); |
98 | w = u.words; |
99 | in6_src = &u.addrs.ip6_src; |
100 | in6_dst = &u.addrs.ip6_dst; |
101 | } |
102 | |
103 | sum += w[0]; |
104 | if (!IN6_IS_SCOPE_EMBEDDABLE(in6_src)) |
105 | sum += w[1]; |
106 | sum += w[2]; |
107 | sum += w[3]; |
108 | sum += w[4]; |
109 | sum += w[5]; |
110 | sum += w[6]; |
111 | sum += w[7]; |
112 | w += 8; |
113 | sum += w[0]; |
114 | if (!IN6_IS_SCOPE_EMBEDDABLE(in6_dst)) |
115 | sum += w[1]; |
116 | sum += w[2]; |
117 | sum += w[3]; |
118 | sum += w[4]; |
119 | sum += w[5]; |
120 | sum += w[6]; |
121 | sum += w[7]; |
122 | |
123 | return cpu_in_cksum(m, len, off, sum); |
124 | } |
125 | |