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      1 /*	$NetBSD: inet_netof.c,v 1.1 2004/05/20 23:13:02 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1983, 1993
      5  *	The Regents of the University of California.  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 University 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 REGENTS 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 REGENTS 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 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)inet_netof.c	8.1 (Berkeley) 6/4/93";
     36 #else
     37 __RCSID("$NetBSD: inet_netof.c,v 1.1 2004/05/20 23:13:02 christos Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include <sys/param.h>
     43 #include <netinet/in.h>
     44 #include <arpa/inet.h>
     45 
     46 #ifdef __weak_alias
     47 __weak_alias(inet_netof,_inet_netof)
     48 #endif
     49 
     50 /*
     51  * Return the network number from an internet
     52  * address; handles class a/b/c network #'s.
     53  */
     54 in_addr_t
     55 inet_netof(struct in_addr in)
     56 {
     57 	in_addr_t i = ntohl(in.s_addr);
     58 
     59 	if (IN_CLASSA(i))
     60 		return (((i)&IN_CLASSA_NET) >> IN_CLASSA_NSHIFT);
     61 	else if (IN_CLASSB(i))
     62 		return (((i)&IN_CLASSB_NET) >> IN_CLASSB_NSHIFT);
     63 	else
     64 		return (((i)&IN_CLASSC_NET) >> IN_CLASSC_NSHIFT);
     65 }
     66