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      1 /*	$NetBSD: if_nametoindex.c,v 1.6 2018/08/22 03:12:31 msaitoh Exp $	*/
      2 /*	$KAME: if_nametoindex.c,v 1.6 2000/11/24 08:18:54 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 1.6 2018/08/22 03:12:31 msaitoh Exp $");
     32 #endif /* LIBC_SCCS and not lint */
     33 
     34 #ifndef RUMP_ACTION
     35 #include "namespace.h"
     36 #endif
     37 #include <sys/types.h>
     38 #include <sys/ioctl.h>
     39 #include <sys/socket.h>
     40 #include <net/if.h>
     41 #include <net/if_dl.h>
     42 #include <ifaddrs.h>
     43 #include <stdlib.h>
     44 #include <string.h>
     45 #include <unistd.h>
     46 #include <errno.h>
     47 
     48 #ifndef RUMP_ACTION
     49 #ifdef __weak_alias
     50 __weak_alias(if_nametoindex,_if_nametoindex)
     51 #endif
     52 #endif
     53 
     54 /*
     55  * From RFC 2553:
     56  *
     57  * 4.1 Name-to-Index
     58  *
     59  *
     60  *    The first function maps an interface name into its corresponding
     61  *    index.
     62  *
     63  *       #include <net/if.h>
     64  *
     65  *       unsigned int  if_nametoindex(const char *ifname);
     66  *
     67  *    If the specified interface name does not exist, the return value is
     68  *    0, and errno is set to ENXIO.  If there was a system error (such as
     69  *    running out of memory), the return value is 0 and errno is set to the
     70  *    proper value (e.g., ENOMEM).
     71  */
     72 
     73 unsigned int
     74 if_nametoindex(const char *ifname)
     75 {
     76 	int s;
     77 	struct ifreq ifr;
     78 	struct ifaddrs *ifaddrs, *ifa;
     79 	unsigned int ni;
     80 
     81 	s = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
     82 	if (s != -1) {
     83 		memset(&ifr, 0, sizeof(ifr));
     84 		strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
     85 		if (ioctl(s, SIOCGIFINDEX, &ifr) != -1) {
     86 			close(s);
     87 			return (ifr.ifr_index);
     88 		}
     89 		close(s);
     90 	}
     91 
     92 	if (getifaddrs(&ifaddrs) < 0)
     93 		return 0;
     94 
     95 	ni = 0;
     96 
     97 	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
     98 		if (ifa->ifa_addr &&
     99 		    ifa->ifa_addr->sa_family == AF_LINK &&
    100 		    strcmp(ifa->ifa_name, ifname) == 0) {
    101 			ni = ((struct sockaddr_dl*)
    102 			    (void *)ifa->ifa_addr)->sdl_index;
    103 			break;
    104 		}
    105 	}
    106 
    107 	freeifaddrs(ifaddrs);
    108 	if (!ni)
    109 		errno = ENXIO;
    110 	return ni;
    111 }
    112