lib/libc/net/if_nametoindex.c

   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  * $FreeBSD: src/lib/libc/net/if_nametoindex.c,v 1.5 2003/05/01 19:03:14 nectar Exp $
  27  * $DragonFly: src/lib/libc/net/if_nametoindex.c,v 1.2 2003/06/17 04:26:44 dillon Exp $
  28  */
  29
  30 #include "namespace.h"
  31 #include <sys/types.h>
  32 #include <sys/socket.h>
  33 #include <sys/sockio.h>
  34 #include <net/if.h>
  35 #include <net/if_dl.h>
  36 #include <ifaddrs.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <errno.h>
  40 #include <unistd.h>
  41 #include "un-namespace.h"
  42
  43 /*
  44  * From RFC 2553:
  45  *
  46  * 4.1 Name-to-Index
  47  *
  48  *
  49  *    The first function maps an interface name into its corresponding
  50  *    index.
  51  *
  52  *       #include <net/if.h>
  53  *
  54  *       unsigned int  if_nametoindex(const char *ifname);
  55  *
  56  *    If the specified interface name does not exist, the return value is
  57  *    0, and errno is set to ENXIO.  If there was a system error (such as
  58  *    running out of memory), the return value is 0 and errno is set to the
  59  *    proper value (e.g., ENOMEM).
  60  */
  61
  62 unsigned int
  63 if_nametoindex(const char *ifname)
  64 {
  65         int s;
  66         struct ifreq ifr;
  67         struct ifaddrs *ifaddrs, *ifa;
  68         unsigned int ni;
  69
  70         s = _socket(AF_INET, SOCK_DGRAM, 0);
  71         if (s != -1) {
  72                 strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
  73                 if (_ioctl(s, SIOCGIFINDEX, &ifr) != -1) {
  74                         _close(s);
  75                         return (ifr.ifr_index);
  76                 }
  77                 _close(s);
  78         }
  79
  80         if (getifaddrs(&ifaddrs) < 0)
  81                 return(0);
  82
  83         ni = 0;
  84
  85         for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
  86                 if (ifa->ifa_addr &&
  87                     ifa->ifa_addr->sa_family == AF_LINK &&
  88                     strcmp(ifa->ifa_name, ifname) == 0) {
  89                         ni = ((struct sockaddr_dl*)ifa->ifa_addr)->sdl_index;
  90                         break;
  91                 }
  92         }
  93
  94         freeifaddrs(ifaddrs);
  95         if (!ni)
  96                 errno = ENXIO;
  97         return(ni);
  98 }