in_cksum.c   [plain text]

/*
 * Copyright (c) 2000-2012 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1988, 1992, 1993
 *	The Regents of the University of California.  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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *	@(#)in_cksum.c	8.1 (Berkeley) 6/10/93
 */

#include <sys/param.h>
#include <machine/endian.h>
#include <sys/mbuf.h>
#include <kern/debug.h>
#include <net/dlil.h>
#include <netinet/in.h>
#define	_IP_VHL
#include <netinet/ip.h>
#include <netinet/ip_var.h>

/*
 * Checksum routine for Internet Protocol family headers (Portable Version).
 *
 * This routine is very heavily used in the network
 * code and should be modified for each CPU to be as fast as possible.
 */
#define REDUCE16 {							  \
	q_util.q = sum;							  \
	l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
	sum = l_util.s[0] + l_util.s[1];				  \
	ADDCARRY(sum);							  \
}

union l_util {
        uint16_t s[2];
        uint32_t l;
};

union q_util {
        uint16_t s[4];
        uint32_t l[2];
        uint64_t q;
};

#define	PREDICT_FALSE(_exp)	__builtin_expect((_exp), 0)

static uint16_t in_cksumdata(const void *buf, int len);

/*
 * Portable version of 16-bit 1's complement sum function that works
 * on a contiguous buffer.  This is used mainly for instances where
 * the caller is certain about the buffer requirements, e.g. for IP
 * header checksum calculation, though it is capable of being used
 * on any arbitrary data span.  The platform-specific cpu_in_cksum()
 * routine might be better-optmized, so use that instead for large
 * data span.
 *
 * The logic is borrowed from <bsd/netinet/cpu_in_cksum.c>
 */

#if ULONG_MAX == 0xffffffffUL
/* 32-bit version */
static uint16_t
in_cksumdata(const void *buf, int mlen)
{
	uint32_t sum, partial;
	unsigned int final_acc;
	const uint8_t *data = (const uint8_t *)buf;
	boolean_t needs_swap, started_on_odd;

	VERIFY(mlen >= 0);

	needs_swap = FALSE;
	started_on_odd = FALSE;

	sum = 0;
	partial = 0;

	if ((uintptr_t)data & 1) {
		/* Align on word boundary */
		started_on_odd = !started_on_odd;
#if BYTE_ORDER == LITTLE_ENDIAN
		partial = *data << 8;
#else
		partial = *data;
#endif
		++data;
		--mlen;
	}
	needs_swap = started_on_odd;
	while (mlen >= 32) {
		__builtin_prefetch(data + 32);
		partial += *(const uint16_t *)(const void *)data;
		partial += *(const uint16_t *)(const void *)(data + 2);
		partial += *(const uint16_t *)(const void *)(data + 4);
		partial += *(const uint16_t *)(const void *)(data + 6);
		partial += *(const uint16_t *)(const void *)(data + 8);
		partial += *(const uint16_t *)(const void *)(data + 10);
		partial += *(const uint16_t *)(const void *)(data + 12);
		partial += *(const uint16_t *)(const void *)(data + 14);
		partial += *(const uint16_t *)(const void *)(data + 16);
		partial += *(const uint16_t *)(const void *)(data + 18);
		partial += *(const uint16_t *)(const void *)(data + 20);
		partial += *(const uint16_t *)(const void *)(data + 22);
		partial += *(const uint16_t *)(const void *)(data + 24);
		partial += *(const uint16_t *)(const void *)(data + 26);
		partial += *(const uint16_t *)(const void *)(data + 28);
		partial += *(const uint16_t *)(const void *)(data + 30);
		data += 32;
		mlen -= 32;
		if (PREDICT_FALSE(partial & 0xc0000000)) {
			if (needs_swap)
				partial = (partial << 8) +
				    (partial >> 24);
			sum += (partial >> 16);
			sum += (partial & 0xffff);
			partial = 0;
		}
	}
	if (mlen & 16) {
		partial += *(const uint16_t *)(const void *)data;
		partial += *(const uint16_t *)(const void *)(data + 2);
		partial += *(const uint16_t *)(const void *)(data + 4);
		partial += *(const uint16_t *)(const void *)(data + 6);
		partial += *(const uint16_t *)(const void *)(data + 8);
		partial += *(const uint16_t *)(const void *)(data + 10);
		partial += *(const uint16_t *)(const void *)(data + 12);
		partial += *(const uint16_t *)(const void *)(data + 14);
		data += 16;
		mlen -= 16;
	}
	/*
	 * mlen is not updated below as the remaining tests
	 * are using bit masks, which are not affected.
	 */
	if (mlen & 8) {
		partial += *(const uint16_t *)(const void *)data;
		partial += *(const uint16_t *)(const void *)(data + 2);
		partial += *(const uint16_t *)(const void *)(data + 4);
		partial += *(const uint16_t *)(const void *)(data + 6);
		data += 8;
	}
	if (mlen & 4) {
		partial += *(const uint16_t *)(const void *)data;
		partial += *(const uint16_t *)(const void *)(data + 2);
		data += 4;
	}
	if (mlen & 2) {
		partial += *(const uint16_t *)(const void *)data;
		data += 2;
	}
	if (mlen & 1) {
#if BYTE_ORDER == LITTLE_ENDIAN
		partial += *data;
#else
		partial += *data << 8;
#endif
		started_on_odd = !started_on_odd;
	}

	if (needs_swap)
		partial = (partial << 8) + (partial >> 24);
	sum += (partial >> 16) + (partial & 0xffff);
	sum = (sum >> 16) + (sum & 0xffff);

	final_acc = ((sum >> 16) & 0xffff) + (sum & 0xffff);
	final_acc = (final_acc >> 16) + (final_acc & 0xffff);

	return (final_acc);
}

#else
/* 64-bit version */
static uint16_t
in_cksumdata(const void *buf, int mlen)
{
	uint64_t sum, partial;
	unsigned int final_acc;
	const uint8_t *data = (const uint8_t *)buf;
	boolean_t needs_swap, started_on_odd;

	VERIFY(mlen >= 0);

	needs_swap = FALSE;
	started_on_odd = FALSE;

	sum = 0;
	partial = 0;

	if ((uintptr_t)data & 1) {
		/* Align on word boundary */
		started_on_odd = !started_on_odd;
#if BYTE_ORDER == LITTLE_ENDIAN
		partial = *data << 8;
#else
		partial = *data;
#endif
		++data;
		--mlen;
	}
	needs_swap = started_on_odd;
	if ((uintptr_t)data & 2) {
		if (mlen < 2)
			goto trailing_bytes;
		partial += *(const uint16_t *)(const void *)data;
		data += 2;
		mlen -= 2;
	}
	while (mlen >= 64) {
		__builtin_prefetch(data + 32);
		__builtin_prefetch(data + 64);
		partial += *(const uint32_t *)(const void *)data;
		partial += *(const uint32_t *)(const void *)(data + 4);
		partial += *(const uint32_t *)(const void *)(data + 8);
		partial += *(const uint32_t *)(const void *)(data + 12);
		partial += *(const uint32_t *)(const void *)(data + 16);
		partial += *(const uint32_t *)(const void *)(data + 20);
		partial += *(const uint32_t *)(const void *)(data + 24);
		partial += *(const uint32_t *)(const void *)(data + 28);
		partial += *(const uint32_t *)(const void *)(data + 32);
		partial += *(const uint32_t *)(const void *)(data + 36);
		partial += *(const uint32_t *)(const void *)(data + 40);
		partial += *(const uint32_t *)(const void *)(data + 44);
		partial += *(const uint32_t *)(const void *)(data + 48);
		partial += *(const uint32_t *)(const void *)(data + 52);
		partial += *(const uint32_t *)(const void *)(data + 56);
		partial += *(const uint32_t *)(const void *)(data + 60);
		data += 64;
		mlen -= 64;
		if (PREDICT_FALSE(partial & (3ULL << 62))) {
			if (needs_swap)
				partial = (partial << 8) +
				    (partial >> 56);
			sum += (partial >> 32);
			sum += (partial & 0xffffffff);
			partial = 0;
		}
	}
	/*
	 * mlen is not updated below as the remaining tests
	 * are using bit masks, which are not affected.
	 */
	if (mlen & 32) {
		partial += *(const uint32_t *)(const void *)data;
		partial += *(const uint32_t *)(const void *)(data + 4);
		partial += *(const uint32_t *)(const void *)(data + 8);
		partial += *(const uint32_t *)(const void *)(data + 12);
		partial += *(const uint32_t *)(const void *)(data + 16);
		partial += *(const uint32_t *)(const void *)(data + 20);
		partial += *(const uint32_t *)(const void *)(data + 24);
		partial += *(const uint32_t *)(const void *)(data + 28);
		data += 32;
	}
	if (mlen & 16) {
		partial += *(const uint32_t *)(const void *)data;
		partial += *(const uint32_t *)(const void *)(data + 4);
		partial += *(const uint32_t *)(const void *)(data + 8);
		partial += *(const uint32_t *)(const void *)(data + 12);
		data += 16;
	}
	if (mlen & 8) {
		partial += *(const uint32_t *)(const void *)data;
		partial += *(const uint32_t *)(const void *)(data + 4);
		data += 8;
	}
	if (mlen & 4) {
		partial += *(const uint32_t *)(const void *)data;
		data += 4;
	}
	if (mlen & 2) {
		partial += *(const uint16_t *)(const void *)data;
		data += 2;
	}
trailing_bytes:
	if (mlen & 1) {
#if BYTE_ORDER == LITTLE_ENDIAN
		partial += *data;
#else
		partial += *data << 8;
#endif
		started_on_odd = !started_on_odd;
	}

	if (needs_swap)
		partial = (partial << 8) + (partial >> 56);
	sum += (partial >> 32) + (partial & 0xffffffff);
	sum = (sum >> 32) + (sum & 0xffffffff);

	final_acc = (sum >> 48) + ((sum >> 32) & 0xffff) +
	    ((sum >> 16) & 0xffff) + (sum & 0xffff);
	final_acc = (final_acc >> 16) + (final_acc & 0xffff);
	final_acc = (final_acc >> 16) + (final_acc & 0xffff);

	return (final_acc);
}
#endif /* ULONG_MAX != 0xffffffffUL */

/*
 * Perform 16-bit 1's complement sum on a contiguous span.
 */
uint16_t
b_sum16(const void *buf, int len)
{
	return (in_cksumdata(buf, len));
}

uint16_t inet_cksum_simple(struct mbuf *, int);
/*
 * For the exported _in_cksum symbol in BSDKernel symbol set.
 */
uint16_t
inet_cksum_simple(struct mbuf *m, int len)
{
	return (inet_cksum(m, 0, 0, len));
}

uint16_t
in_addword(uint16_t a, uint16_t b)
{
	uint64_t sum = a + b;

	ADDCARRY(sum);
	return (sum);
}

uint16_t
in_pseudo(uint32_t a, uint32_t b, uint32_t c)
{
        uint64_t sum;
        union q_util q_util;
        union l_util l_util;

        sum = (uint64_t)a + b + c;
        REDUCE16;
        return (sum);
}

uint16_t
in_pseudo64(uint64_t a, uint64_t b, uint64_t c)
{
	uint64_t sum;
	union q_util q_util;
	union l_util l_util;

	sum = a + b + c;
	REDUCE16;
	return (sum);
}

/*
 * May be used on IP header with options.
 */
uint16_t
in_cksum_hdr_opt(const struct ip *ip)
{
	return (~b_sum16(ip, (IP_VHL_HL(ip->ip_vhl) << 2)) & 0xffff);
}

/*
 * A wrapper around the simple in_cksum_hdr() and the more complicated
 * inet_cksum(); the former is chosen if the IP header is simple,
 * contiguous and 32-bit aligned.  Also does some stats accounting.
 */
uint16_t
ip_cksum_hdr_dir(struct mbuf *m, uint32_t hlen, int out)
{
	struct ip *ip = mtod(m, struct ip *);

	if (out) {
		ipstat.ips_snd_swcsum++;
		ipstat.ips_snd_swcsum_bytes += hlen;
	} else {
		ipstat.ips_rcv_swcsum++;
		ipstat.ips_rcv_swcsum_bytes += hlen;
	}

	if (hlen == sizeof (*ip) &&
	    m->m_len >= sizeof (*ip) && IP_HDR_ALIGNED_P(ip))
		return (in_cksum_hdr(ip));

	return (inet_cksum(m, 0, 0, hlen));
}

/*
 * m MUST contain at least an IP header, if nxt is specified;
 * nxt is the upper layer protocol number;
 * off is an offset where TCP/UDP/ICMP header starts;
 * len is a total length of a transport segment (e.g. TCP header + TCP payload)
 */
uint16_t
inet_cksum(struct mbuf *m, uint32_t nxt, uint32_t off, uint32_t len)
{
	uint32_t sum;

	sum = m_sum16(m, off, len);

	/* include pseudo header checksum? */
	if (nxt != 0) {
		struct ip *ip;
		unsigned char buf[sizeof ((*ip))] __attribute__((aligned(8)));
		uint32_t mlen;

		/*
		 * Sanity check
		 *
		 * Use m_length2() instead of m_length(), as we cannot rely on
		 * the caller setting m_pkthdr.len correctly, if the mbuf is
		 * a M_PKTHDR one.
		 */
		if ((mlen = m_length2(m, NULL)) < sizeof (*ip)) {
			panic("%s: mbuf %p too short (%d) for IPv4 header",
			    __func__, m, mlen);
			/* NOTREACHED */
		}

		/*
		 * In case the IP header is not contiguous, or not 32-bit
		 * aligned, copy it to a local buffer.  Note here that we
		 * expect the data pointer to point to the IP header.
		 */
		if ((sizeof (*ip) > m->m_len) ||
		    !IP_HDR_ALIGNED_P(mtod(m, caddr_t))) {
			m_copydata(m, 0, sizeof (*ip), (caddr_t)buf);
			ip = (struct ip *)(void *)buf;
		} else {
			ip = (struct ip *)(void *)(m->m_data);
		}

		/* add pseudo header checksum */
		sum += in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
		    htonl(len + nxt));

		/* fold in carry bits */
		ADDCARRY(sum);
	}

	return (~sum & 0xffff);
}