FreeBSD/Linux Kernel Cross Reference
sys/netpfil/pf/in4_cksum.c

     /*      $FreeBSD: releng/11.0/sys/netpfil/pf/in4_cksum.c 240494 2012-09-14 11:51:49Z glebius $  */
     /*      $OpenBSD: in4_cksum.c,v 1.7 2003/06/02 23:28:13 millert Exp $   */
     /*      $KAME: in4_cksum.c,v 1.10 2001/11/30 10:06:15 itojun Exp $      */
     /*      $NetBSD: in_cksum.c,v 1.13 1996/10/13 02:03:03 christos Exp $   */
     
     /*
      * Copyright (C) 1999 WIDE Project.
      * 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. Neither the name of the project 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 PROJECT 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 PROJECT 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.
     */
    
    /*
     * 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. 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 <sys/systm.h>
    #include <sys/mbuf.h>
    
    #include <netinet/in.h>
    #include <netinet/in_systm.h>
    #include <netinet/ip.h>
    #include <netinet/ip_var.h>
    
    #include <machine/in_cksum.h>
    
    #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
    #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; (void)ADDCARRY(sum);}
    
    int in4_cksum(struct mbuf *, u_int8_t, int, int);
    
    int
    in4_cksum(struct mbuf *m, u_int8_t nxt, int off, int len)
    {
            union {
                    struct ipovly ipov;
                    u_int16_t w[10];
            } u;
            union {
                    u_int16_t s[2];
                    u_int32_t l;
            } l_util;
    
            u_int16_t *w;
            int psum;
            int sum = 0;
    
            if (nxt != 0) {
                    /* pseudo header */
                   if (off < sizeof(struct ipovly))
                           panic("in4_cksum: offset too short");
                   if (m->m_len < sizeof(struct ip))
                           panic("in4_cksum: bad mbuf chain");
                   bzero(&u.ipov, sizeof(u.ipov));
                   u.ipov.ih_len = htons(len);
                   u.ipov.ih_pr = nxt;
                   u.ipov.ih_src = mtod(m, struct ip *)->ip_src;
                   u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst;
                   w = u.w;
                   /* assumes sizeof(ipov) == 20 */
                   sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4];
                   sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9];
           }
   
           psum = in_cksum_skip(m, len + off, off);
           psum = ~psum & 0xffff;
           sum += psum;
           REDUCE;
           return (~sum & 0xffff);
   }

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