xref: /freebsd/lib/libc/inet/inet_netof.c (revision e9ac41698b2f322d55ccf9da50a3596edb2c1800)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
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 "port_before.h"
33 
34 #include <sys/param.h>
35 #include <netinet/in.h>
36 #include <arpa/inet.h>
37 
38 #include "port_after.h"
39 
40 /*%
41  * Return the network number from an internet
42  * address; handles class a/b/c network #'s.
43  */
44 in_addr_t
45 inet_netof(struct in_addr in)
46 {
47 	in_addr_t i = ntohl(in.s_addr);
48 
49 	if (IN_CLASSA(i))
50 		return (((i)&IN_CLASSA_NET) >> IN_CLASSA_NSHIFT);
51 	else if (IN_CLASSB(i))
52 		return (((i)&IN_CLASSB_NET) >> IN_CLASSB_NSHIFT);
53 	else
54 		return (((i)&IN_CLASSC_NET) >> IN_CLASSC_NSHIFT);
55 }
56 
57 /*
58  * Weak aliases for applications that use certain private entry points,
59  * and fail to include <arpa/inet.h>.
60  */
61 #undef inet_netof
62 __weak_reference(__inet_netof, inet_netof);
63 
64 /*! \file */
65