StdLib/LibC/NetUtil/inet_netof.c

   1 /** @File
   2   Return the network number from an internet address.
   3
   4   Copyright (c) 2011, Intel Corporation. All rights reserved.<BR>
   5   This program and the accompanying materials are licensed and made available under
   6   the terms and conditions of the BSD License that accompanies this distribution.
   7   The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13  * Copyright (c) 1983, 1993
  14  *  The Regents of the University of California.  All rights reserved.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  * 3. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39
  40   NetBSD: inet_netof.c,v 1.1 2004/05/20 23:13:02 christos Exp
  41   inet_netof.c  8.1 (Berkeley) 6/4/93
  42 **/
  43 #include  <LibConfig.h>
  44
  45 #include "namespace.h"
  46 #include <sys/param.h>
  47 #include <netinet/in.h>
  48 #include <arpa/inet.h>
  49
  50 #ifdef __weak_alias
  51 __weak_alias(inet_netof,_inet_netof)
  52 #endif
  53
  54 /*
  55  * Return the network number from an internet
  56  * address; handles class a/b/c network #'s.
  57  */
  58 in_addr_t
  59 inet_netof(struct in_addr in)
  60 {
  61   in_addr_t i = ntohl(in.s_addr);
  62
  63   if (IN_CLASSA(i))
  64     return (((i)&IN_CLASSA_NET) >> IN_CLASSA_NSHIFT);
  65   else if (IN_CLASSB(i))
  66     return (((i)&IN_CLASSB_NET) >> IN_CLASSB_NSHIFT);
  67   else
  68     return (((i)&IN_CLASSC_NET) >> IN_CLASSC_NSHIFT);
  69 }