1 /* $NetBSD: if_indextoname.c,v 1.7 2010/12/13 23:10:12 pooka Exp $ */
2 /* $KAME: if_indextoname.c,v 1.7 2000/11/08 03:09:30 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_indextoname.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_indextoname.c,v 1.7 2010/12/13 23:10:12 pooka 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/socket.h>
39 #include <net/if_dl.h>
40 #include <net/if.h>
41 #include <ifaddrs.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <errno.h>
45
46 #ifndef RUMP_ACTION
47 #ifdef __weak_alias
__weak_alias(if_indextoname,_if_indextoname)48 __weak_alias(if_indextoname,_if_indextoname)
49 #endif
50 #endif
51
52 /*
53 * From RFC 2533:
54 *
55 * The second function maps an interface index into its corresponding
56 * name.
57 *
58 * #include <net/if.h>
59 *
60 * char *if_indextoname(unsigned int ifindex, char *ifname);
61 *
62 * The ifname argument must point to a buffer of at least IF_NAMESIZE
63 * bytes into which the interface name corresponding to the specified
64 * index is returned. (IF_NAMESIZE is also defined in <net/if.h> and
65 * its value includes a terminating null byte at the end of the
66 * interface name.) This pointer is also the return value of the
67 * function. If there is no interface corresponding to the specified
68 * index, NULL is returned, and errno is set to ENXIO, if there was a
69 * system error (such as running out of memory), if_indextoname returns
70 * NULL and errno would be set to the proper value (e.g., ENOMEM).
71 */
72
73 char *
74 if_indextoname(unsigned int ifindex, char *ifname)
75 {
76 struct ifaddrs *ifaddrs, *ifa;
77 int error = 0;
78
79 if (getifaddrs(&ifaddrs) < 0)
80 return(NULL); /* getifaddrs properly set errno */
81
82 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
83 if (ifa->ifa_addr &&
84 ifa->ifa_addr->sa_family == AF_LINK &&
85 ifindex == ((struct sockaddr_dl*)
86 (void *)ifa->ifa_addr)->sdl_index)
87 break;
88 }
89
90 if (ifa == NULL) {
91 error = ENXIO;
92 ifname = NULL;
93 }
94 else
95 strlcpy(ifname, ifa->ifa_name, IFNAMSIZ);
96
97 freeifaddrs(ifaddrs);
98
99 errno = error;
100 return(ifname);
101 }
102