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in4_cksum.c revision 1.15 
      1 /*	$NetBSD: in4_cksum.c,v 1.15 2008/01/25 21:12:15 joerg Exp $	*/
      2 
      3 /*
      4  * Copyright (C) 1999 WIDE Project.
      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  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the project nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 /*
     33  * Copyright (c) 1988, 1992, 1993
     34  *	The Regents of the University of California.  All rights reserved.
     35  *
     36  * Redistribution and use in source and binary forms, with or without
     37  * modification, are permitted provided that the following conditions
     38  * are met:
     39  * 1. Redistributions of source code must retain the above copyright
     40  *    notice, this list of conditions and the following disclaimer.
     41  * 2. Redistributions in binary form must reproduce the above copyright
     42  *    notice, this list of conditions and the following disclaimer in the
     43  *    documentation and/or other materials provided with the distribution.
     44  * 3. Neither the name of the University nor the names of its contributors
     45  *    may be used to endorse or promote products derived from this software
     46  *    without specific prior written permission.
     47  *
     48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     58  * SUCH DAMAGE.
     59  *
     60  *	@(#)in_cksum.c	8.1 (Berkeley) 6/10/93
     61  */
     62 
     63 #include <sys/cdefs.h>
     64 __KERNEL_RCSID(0, "$NetBSD: in4_cksum.c,v 1.15 2008/01/25 21:12:15 joerg Exp $");
     65 
     66 #include <sys/param.h>
     67 #include <sys/mbuf.h>
     68 #include <sys/systm.h>
     69 #include <sys/socket.h>
     70 #include <net/route.h>
     71 #include <netinet/in.h>
     72 #include <netinet/in_systm.h>
     73 #include <netinet/ip.h>
     74 #include <netinet/ip_var.h>
     75 
     76 /*
     77  * Checksum routine for Internet Protocol family headers (Portable Version).
     78  * This is only for IPv4 pseudo header checksum.
     79  * No need to clear non-pseudo-header fields in IPv4 header.
     80  * len is for actual payload size, and does not include IPv4 header and
     81  * skipped header chain (off + len should be equal to the whole packet).
     82  */
     83 
     84 int
     85 in4_cksum(struct mbuf *m, u_int8_t nxt, int off, int len)
     86 {
     87 	uint32_t sum;
     88 	union {
     89 		struct ipovly ipov;
     90 		uint16_t w[10];
     91 	} u;
     92 	uint16_t *w;
     93 
     94 	sum = 0;
     95 
     96 	if (nxt == 0)
     97 		goto skip_phdr;
     98 
     99 	/* pseudo header */
    100 	if (off < sizeof(struct ipovly))
    101 		panic("in4_cksum: offset too short");
    102 	if (m->m_len < sizeof(struct ip))
    103 		panic("in4_cksum: bad mbuf chain");
    104 	bzero(&u.ipov, sizeof(u.ipov));
    105 	u.ipov.ih_len = htons(len);
    106 	u.ipov.ih_pr = nxt;
    107 	u.ipov.ih_src = mtod(m, struct ip *)->ip_src;
    108 	u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst;
    109 	w = u.w;
    110 	/* assumes sizeof(ipov) == 20 */
    111 	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4];
    112 	sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9];
    113 
    114  skip_phdr:
    115 	return cpu_in_cksum(m, len, off, sum);
    116 }
    117