lib/libc/net/if_nametoindex.c

   1 /*      $NetBSD: if_nametoindex.c,v 1.4 2000/11/24 08:21:12 itojun 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 1.4 2000/11/24 08:21:12 itojun 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 #include <errno.h>
  43
  44 #ifdef __weak_alias
  45 __weak_alias(if_nametoindex,_if_nametoindex)
  46 #endif
  47
  48 /*
  49  * From RFC 2553:
  50  *
  51  * 4.1 Name-to-Index
  52  *
  53  *
  54  *    The first function maps an interface name into its corresponding
  55  *    index.
  56  *
  57  *       #include <net/if.h>
  58  *
  59  *       unsigned int  if_nametoindex(const char *ifname);
  60  *
  61  *    If the specified interface name does not exist, the return value is
  62  *    0, and errno is set to ENXIO.  If there was a system error (such as
  63  *    running out of memory), the return value is 0 and errno is set to the
  64  *    proper value (e.g., ENOMEM).
  65  */
  66
  67 unsigned int
  68 if_nametoindex(const char *ifname)
  69 {
  70         struct ifaddrs *ifaddrs, *ifa;
  71         unsigned int ni;
  72
  73         if (getifaddrs(&ifaddrs) < 0)
  74                 return(0);
  75
  76         ni = 0;
  77
  78         for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
  79                 if (ifa->ifa_addr &&
  80                     ifa->ifa_addr->sa_family == AF_LINK &&
  81                     strcmp(ifa->ifa_name, ifname) == 0) {
  82                         ni = ((struct sockaddr_dl*)
  83                             (void *)ifa->ifa_addr)->sdl_index;
  84                         break;
  85                 }
  86         }
  87
  88         freeifaddrs(ifaddrs);
  89         if (!ni)
  90                 errno = ENXIO;
  91         return(ni);
  92 }