/* $NetBSD: in6_cksum.c,v 1.28 2011/04/25 22:05:05 yamt Exp $ */
/*-
* Copyright (c) 2008 Joerg Sonnenberger <
[email protected]>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: in6_cksum.c,v 1.28 2011/04/25 22:05:05 yamt Exp $");
#include <sys/param.h>
#include <sys/mbuf.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
/*
* Checksum of the IPv6 pseudo header.
*
* off is supposed to be the skipped IPv6 header, len is the payload size.
*/
int
in6_cksum(struct mbuf *m, u_int8_t nxt, uint32_t off, uint32_t len)
{
union {
uint16_t words[16];
struct {
struct in6_addr ip6_src;
struct in6_addr ip6_dst;
} addrs;
} u;
const struct in6_addr *in6_src;
const struct in6_addr *in6_dst;
const struct ip6_hdr *ip6;
uint32_t sum;
const uint16_t *w;
const char *cp;
if (nxt == 0)
return cpu_in_cksum(m, len, off, 0);
if (__predict_false(off < sizeof(struct ip6_hdr)))
panic("in6_cksum: offset too short for IPv6 header");
if (__predict_false(m->m_len < sizeof(struct ip6_hdr)))
panic("in6_cksum: mbuf too short for IPv6 header");
/*
* Compute the equivalent of:
* struct ip6_hdr_pseudo ip6;
*
* bzero(sizeof(*ip6));
* ip6.ip6ph_nxt = nxt;
* ip6.ip6ph_len = htonl(len);
* ipv6.ip6ph_src = mtod(m, struct ip6_hdr *)->ip6_src;
* in6_clearscope(&ip6->ip6ph_src);
* ipv6.ip6ph_dst = mtod(m, struct ip6_hdr *)->ip6_dst;
* in6_clearscope(&ip6->ip6ph_dst);
* sum = one_add(&ip6);
*/
#if BYTE_ORDER == LITTLE_ENDIAN
sum = ((len & 0xffff) + ((len >> 16) & 0xffff) + nxt) << 8;
#else
sum = (len & 0xffff) + ((len >> 16) & 0xffff) + nxt;
#endif
cp = mtod(m, const char *);
w = (const uint16_t *)(cp + offsetof(struct ip6_hdr, ip6_src));
ip6 = (const void *)cp;
if (__predict_true((uintptr_t)w % 2 == 0)) {
in6_src = &ip6->ip6_src;
in6_dst = &ip6->ip6_dst;
} else {
memcpy(&u, &ip6->ip6_src, 32);
w = u.words;
in6_src = &u.addrs.ip6_src;
in6_dst = &u.addrs.ip6_dst;
}
sum += w[0];
if (!IN6_IS_SCOPE_EMBEDDABLE(in6_src))
sum += w[1];
sum += w[2];
sum += w[3];
sum += w[4];
sum += w[5];
sum += w[6];
sum += w[7];
w += 8;
sum += w[0];
if (!IN6_IS_SCOPE_EMBEDDABLE(in6_dst))
sum += w[1];
sum += w[2];
sum += w[3];
sum += w[4];
sum += w[5];
sum += w[6];
sum += w[7];
return cpu_in_cksum(m, len, off, sum);
}
