1/* $NetBSD: in6_cksum.c,v 1.27 2008/03/10 22:34:40 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 1.27 2008/03/10 22:34:40 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 46int 47in6_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