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glibc  2.9
inet_netof.c
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00001 /*
00002  * Copyright (c) 1983, 1993
00003  *     The Regents of the University of California.  All rights reserved.
00004  *
00005  * Redistribution and use in source and binary forms, with or without
00006  * modification, are permitted provided that the following conditions
00007  * are met:
00008  * 1. Redistributions of source code must retain the above copyright
00009  *    notice, this list of conditions and the following disclaimer.
00010  * 2. Redistributions in binary form must reproduce the above copyright
00011  *    notice, this list of conditions and the following disclaimer in the
00012  *    documentation and/or other materials provided with the distribution.
00013  * 4. Neither the name of the University nor the names of its contributors
00014  *    may be used to endorse or promote products derived from this software
00015  *    without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
00018  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00019  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00020  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
00021  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00022  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00023  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00024  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00025  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00026  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00027  * SUCH DAMAGE.
00028  */
00029 
00030 #if defined(LIBC_SCCS) && !defined(lint)
00031 static char sccsid[] = "@(#)inet_netof.c  8.1 (Berkeley) 6/4/93";
00032 #endif /* LIBC_SCCS and not lint */
00033 
00034 #include <sys/param.h>
00035 #include <netinet/in.h>
00036 #include <arpa/inet.h>
00037 
00038 /*
00039  * Return the network number from an internet
00040  * address; handles class a/b/c network #'s.
00041  */
00042 in_addr_t
00043 inet_netof(in)
00044        struct in_addr in;
00045 {
00046        register u_int32_t i = ntohl(in.s_addr);
00047 
00048        if (IN_CLASSA(i))
00049               return (((i)&IN_CLASSA_NET) >> IN_CLASSA_NSHIFT);
00050        else if (IN_CLASSB(i))
00051               return (((i)&IN_CLASSB_NET) >> IN_CLASSB_NSHIFT);
00052        else
00053               return (((i)&IN_CLASSC_NET) >> IN_CLASSC_NSHIFT);
00054 }
00055 libc_hidden_def (inet_netof)