1 | /* $NetBSD: in4_cksum.c,v 1.20 2014/11/30 18:15:41 christos 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: in4_cksum.c,v 1.20 2014/11/30 18:15:41 christos Exp $" ); |
34 | |
35 | #include <sys/param.h> |
36 | #include <sys/mbuf.h> |
37 | #include <netinet/in.h> |
38 | #include <netinet/in_systm.h> |
39 | #include <netinet/ip.h> |
40 | |
41 | /* |
42 | * Checksum of the IPv4 pseudo header. |
43 | * |
44 | * off is supposed to be the skipped IPv4 header, len is the payload size. |
45 | */ |
46 | #ifdef DIAGNOSTIC |
47 | #define PANIC(a,...) panic(a, __VA_ARGS__) |
48 | #else |
49 | #define PANIC(a,...) do { \ |
50 | printf(a, __VA_ARGS__); \ |
51 | return -1; \ |
52 | } while (/*CONSTCOND*/0) |
53 | #endif |
54 | |
55 | int |
56 | in4_cksum(struct mbuf *m, u_int8_t nxt, int off, int len) |
57 | { |
58 | uint32_t sum; |
59 | uint16_t *w; |
60 | |
61 | if (__predict_false(m->m_len < sizeof(struct ip))) |
62 | PANIC("%s: mbuf %d too short for IP header %zu" , __func__, |
63 | m->m_len, sizeof(struct ip)); |
64 | |
65 | if (nxt == 0) |
66 | return cpu_in_cksum(m, len, off, 0); |
67 | |
68 | if (__predict_false(off < sizeof(struct ip))) |
69 | PANIC("%s: offset %d too short for IP header %zu" , __func__, |
70 | off, sizeof(struct ip)); |
71 | |
72 | /* |
73 | * Compute the equivalent of: |
74 | * struct ipovly ip; |
75 | * |
76 | * bzero(sizeof(*ip)); |
77 | * ip.ih_pr = nxt; |
78 | * ip.ip_len = htons(len); |
79 | * ip.ih_src = mtod(m, struct ip *)->ip_src; |
80 | * ip.ih_dst = mtod(m, struct ip *)->ip_dst; |
81 | * sum = one_add(&ip); |
82 | */ |
83 | |
84 | #if BYTE_ORDER == LITTLE_ENDIAN |
85 | sum = ((len & 0xffff) + nxt) << 8; |
86 | #else |
87 | sum = (len & 0xffff) + nxt; |
88 | #endif |
89 | w = (uint16_t *)(mtod(m, char *) + offsetof(struct ip, ip_src)); |
90 | if (__predict_true((uintptr_t)w % 2 == 0)) { |
91 | sum += w[0]; |
92 | sum += w[1]; |
93 | sum += w[2]; |
94 | sum += w[3]; |
95 | } else { |
96 | uint32_t partial; |
97 | w = (void *)((uintptr_t)w - 1); |
98 | #if BYTE_ORDER == LITTLE_ENDIAN |
99 | partial = w[0] & 0xff00; |
100 | #else |
101 | partial = w[0] & 0x00ff; |
102 | #endif |
103 | partial += w[1]; |
104 | partial += w[2]; |
105 | partial += w[3]; |
106 | #if BYTE_ORDER == LITTLE_ENDIAN |
107 | partial += w[4] & 0x00ff; |
108 | #else |
109 | partial += w[4] & 0xff00; |
110 | #endif |
111 | sum += partial << 8; |
112 | } |
113 | |
114 | return cpu_in_cksum(m, len, off, sum); |
115 | } |
116 | |