gen.subproj/if_indextoname.c

   1 /*
   2  * Copyright (c) 2018 Apple Inc. All rights reserved.
   3  */
   4 /*      $KAME: if_indextoname.c,v 1.7 2000/11/08 03:09:30 itojun Exp $  */
   5
   6 /*-
   7  * Copyright (c) 1997, 2000
   8  *      Berkeley Software Design, Inc.  All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  *      BSDI Id: if_indextoname.c,v 2.3 2000/04/17 22:38:05 dab Exp
  29  */
  30
  31 #include "libinfo_common.h"
  32
  33 #include <sys/types.h>
  34 #include <sys/socket.h>
  35 #include <net/if_dl.h>
  36 #include <net/if.h>
  37 #include <ifaddrs.h>
  38 #include <stdlib.h>
  39 #include <string.h>
  40 #include <errno.h>
  41
  42 /*
  43  * From RFC 2533:
  44  *
  45  * The second function maps an interface index into its corresponding
  46  * name.
  47  *
  48  *    #include <net/if.h>
  49  *
  50  *    char  *if_indextoname(unsigned int ifindex, char *ifname);
  51  *
  52  * The ifname argument must point to a buffer of at least IF_NAMESIZE
  53  * bytes into which the interface name corresponding to the specified
  54  * index is returned.  (IF_NAMESIZE is also defined in <net/if.h> and
  55  * its value includes a terminating null byte at the end of the
  56  * interface name.) This pointer is also the return value of the
  57  * function.  If there is no interface corresponding to the specified
  58  * index, NULL is returned, and errno is set to ENXIO, if there was a
  59  * system error (such as running out of memory), if_indextoname returns
  60  * NULL and errno would be set to the proper value (e.g., ENOMEM).
  61  */
  62
  63 LIBINFO_EXPORT
  64 char *
  65 if_indextoname(unsigned int ifindex, char *ifname)
  66 {
  67         struct ifaddrs *ifaddrs, *ifa;
  68         int error = 0;
  69
  70         if (getifaddrs(&ifaddrs) < 0)
  71                 return(NULL);   /* getifaddrs properly set errno */
  72
  73         for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
  74                 if (ifa->ifa_addr &&
  75                     ifa->ifa_addr->sa_family == AF_LINK &&
  76                     ifindex == ((struct sockaddr_dl*)ifa->ifa_addr)->sdl_index)
  77                         break;
  78         }
  79
  80         if (ifa == NULL) {
  81                 error = ENXIO;
  82                 ifname = NULL;
  83         }
  84         else
  85                 strncpy(ifname, ifa->ifa_name, IFNAMSIZ);
  86
  87         freeifaddrs(ifaddrs);
  88
  89         errno = error;
  90         return(ifname);
  91 }