| 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 | |