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if_nametoindex.c revision 1.3 
      1 /*	$NetBSD: if_nametoindex.c,v 1.3 2000/07/06 02:56:25 christos Exp $	*/
      2 /*	$KAME: if_nametoindex.c,v 1.4 2000/04/24 10:08:41 itojun Exp $	*/
      3 
      4 /*-
      5  * Copyright (c) 1997, 2000
      6  *	Berkeley Software Design, Inc.  All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  *
     14  * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
     15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     17  * ARE DISCLAIMED.  IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
     18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     24  * SUCH DAMAGE.
     25  *
     26  *	BSDI Id: if_nametoindex.c,v 2.3 2000/04/17 22:38:05 dab Exp
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 #if defined(LIBC_SCCS) && !defined(lint)
     31 __RCSID("$NetBSD: if_nametoindex.c,v 1.3 2000/07/06 02:56:25 christos Exp $");
     32 #endif /* LIBC_SCCS and not lint */
     33 
     34 #include "namespace.h"
     35 #include <sys/types.h>
     36 #include <sys/socket.h>
     37 #include <net/if.h>
     38 #include <net/if_dl.h>
     39 #include <ifaddrs.h>
     40 #include <stdlib.h>
     41 #include <string.h>
     42 
     43 #ifdef __weak_alias
     44 __weak_alias(if_nametoindex,_if_nametoindex)
     45 #endif
     46 
     47 /*
     48  * From RFC 2133:
     49  *
     50  * 4.1.  Name-to-Index
     51  *
     52  *    The first function maps an interface name into its corresponding
     53  *    index.
     54  *
     55  *        #include <net/if.h>
     56  *
     57  *        unsigned int  if_nametoindex(const char *ifname);
     58  *
     59  *    If the specified interface does not exist, the return value is 0.
     60  */
     61 
     62 unsigned int
     63 if_nametoindex(const char *ifname)
     64 {
     65 	struct ifaddrs *ifaddrs, *ifa;
     66 	unsigned int ni;
     67 
     68 	if (getifaddrs(&ifaddrs) < 0)
     69 		return(0);
     70 
     71 	ni = 0;
     72 
     73 	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
     74 		if (ifa->ifa_addr &&
     75 		    ifa->ifa_addr->sa_family == AF_LINK &&
     76 		    strcmp(ifa->ifa_name, ifname) == 0) {
     77 			ni = ((struct sockaddr_dl*)
     78 			    (void *)ifa->ifa_addr)->sdl_index;
     79 			break;
     80 		}
     81 	}
     82 
     83 	freeifaddrs(ifaddrs);
     84 	return(ni);
     85 }
     86