if_nametoindex.c revision 100138 
1/*	$KAME: if_nametoindex.c,v 1.6 2000/11/24 08:18:54 itojun Exp $	*/
2
3/*-
4 * Copyright (c) 1997, 2000
5 *	Berkeley Software Design, Inc.  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 *
13 * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED.  IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 *
25 *	BSDI Id: if_nametoindex.c,v 2.3 2000/04/17 22:38:05 dab Exp
26 */
27
28#include <sys/cdefs.h>
29__FBSDID("$FreeBSD: head/lib/libc/net/if_nametoindex.c 100138 2002-07-15 19:58:56Z ume $");
30
31#include <sys/types.h>
32#include <sys/socket.h>
33#include <net/if.h>
34#include <net/if_dl.h>
35#include <ifaddrs.h>
36#include <stdlib.h>
37#include <string.h>
38#include <errno.h>
39
40/*
41 * From RFC 2553:
42 *
43 * 4.1 Name-to-Index
44 *
45 *
46 *    The first function maps an interface name into its corresponding
47 *    index.
48 *
49 *       #include <net/if.h>
50 *
51 *       unsigned int  if_nametoindex(const char *ifname);
52 *
53 *    If the specified interface name does not exist, the return value is
54 *    0, and errno is set to ENXIO.  If there was a system error (such as
55 *    running out of memory), the return value is 0 and errno is set to the
56 *    proper value (e.g., ENOMEM).
57 */
58
59unsigned int
60if_nametoindex(const char *ifname)
61{
62	struct ifaddrs *ifaddrs, *ifa;
63	unsigned int ni;
64
65	if (getifaddrs(&ifaddrs) < 0)
66		return(0);
67
68	ni = 0;
69
70	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
71		if (ifa->ifa_addr &&
72		    ifa->ifa_addr->sa_family == AF_LINK &&
73		    strcmp(ifa->ifa_name, ifname) == 0) {
74			ni = ((struct sockaddr_dl*)ifa->ifa_addr)->sdl_index;
75			break;
76		}
77	}
78
79	freeifaddrs(ifaddrs);
80	if (!ni)
81		errno = ENXIO;
82	return(ni);
83}
84