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      1 /*	$OpenBSD: inet_makeaddr.c,v 1.7 2015/01/16 16:48:51 deraadt Exp $ */
      2 /*
      3  * Copyright (c) 1983, 1993
      4  *	The Regents of the University of California.  All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. Neither the name of the University nor the names of its contributors
     15  *    may be used to endorse or promote products derived from this software
     16  *    without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     28  * SUCH DAMAGE.
     29  */
     30 
     31 #include <netinet/in.h>
     32 #include <arpa/inet.h>
     33 
     34 /*
     35  * Formulate an Internet address from network + host.  Used in
     36  * building addresses stored in the ifnet structure.
     37  */
     38 struct in_addr
     39 inet_makeaddr(in_addr_t net, in_addr_t host)
     40 {
     41 	in_addr_t addr;
     42 
     43 	if (net < 128)
     44 		addr = (net << IN_CLASSA_NSHIFT) | (host & IN_CLASSA_HOST);
     45 	else if (net < 65536)
     46 		addr = (net << IN_CLASSB_NSHIFT) | (host & IN_CLASSB_HOST);
     47 	else if (net < 16777216L)
     48 		addr = (net << IN_CLASSC_NSHIFT) | (host & IN_CLASSC_HOST);
     49 	else
     50 		addr = net | host;
     51 	addr = htonl(addr);
     52 	return (*(struct in_addr *)&addr);
     53 }
     54