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1 | /* $KAME: if_indextoname.c,v 1.7 2000/11/08 03:09:30 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_indextoname.c,v 2.3 2000/04/17 22:38:05 dab Exp | |
26 | */ | |
27 | ||
28 | #include <sys/types.h> | |
29 | #include <sys/socket.h> | |
30 | #include <net/if_dl.h> | |
31 | #include <net/if.h> | |
32 | #include <ifaddrs.h> | |
33 | #include <stdlib.h> | |
34 | #include <string.h> | |
35 | #include <errno.h> | |
36 | ||
37 | /* | |
38 | * From RFC 2533: | |
39 | * | |
40 | * The second function maps an interface index into its corresponding | |
41 | * name. | |
42 | * | |
43 | * #include <net/if.h> | |
44 | * | |
45 | * char *if_indextoname(unsigned int ifindex, char *ifname); | |
46 | * | |
47 | * The ifname argument must point to a buffer of at least IF_NAMESIZE | |
48 | * bytes into which the interface name corresponding to the specified | |
49 | * index is returned. (IF_NAMESIZE is also defined in <net/if.h> and | |
50 | * its value includes a terminating null byte at the end of the | |
51 | * interface name.) This pointer is also the return value of the | |
52 | * function. If there is no interface corresponding to the specified | |
53 | * index, NULL is returned, and errno is set to ENXIO, if there was a | |
54 | * system error (such as running out of memory), if_indextoname returns | |
55 | * NULL and errno would be set to the proper value (e.g., ENOMEM). | |
56 | */ | |
57 | ||
58 | char * | |
59 | if_indextoname(unsigned int ifindex, char *ifname) | |
60 | { | |
61 | struct ifaddrs *ifaddrs, *ifa; | |
62 | int error = 0; | |
63 | ||
64 | if (getifaddrs(&ifaddrs) < 0) | |
65 | return(NULL); /* getifaddrs properly set errno */ | |
66 | ||
67 | for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) { | |
68 | if (ifa->ifa_addr && | |
69 | ifa->ifa_addr->sa_family == AF_LINK && | |
70 | ifindex == ((struct sockaddr_dl*)ifa->ifa_addr)->sdl_index) | |
71 | break; | |
72 | } | |
73 | ||
74 | if (ifa == NULL) { | |
75 | error = ENXIO; | |
76 | ifname = NULL; | |
77 | } | |
78 | else | |
79 | strncpy(ifname, ifa->ifa_name, IFNAMSIZ); | |
80 | ||
81 | freeifaddrs(ifaddrs); | |
82 | ||
83 | errno = error; | |
84 | return(ifname); | |
85 | } |