usr/src/lib/libbc/libc/inet/inet_netof.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 1983 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include <sys/types.h>
  30 #include <netinet/in.h>
  31
  32 /*
  33  * Return the network number from an internet
  34  * address; handles class a/b/c network #'s.
  35  */
  36 int
  37 inet_netof(struct in_addr in)
  38 {
  39         u_long i = ntohl(in.s_addr);
  40
  41         if (IN_CLASSA(i))
  42                 return (((i)&IN_CLASSA_NET) >> IN_CLASSA_NSHIFT);
  43         else if (IN_CLASSB(i))
  44                 return (((i)&IN_CLASSB_NET) >> IN_CLASSB_NSHIFT);
  45         else
  46                 return (((i)&IN_CLASSC_NET) >> IN_CLASSC_NSHIFT);
  47 }