lib/libc/net/if_nameindex.c

   1 /*      $NetBSD: if_nameindex.c,v 1.7 2012/03/13 21:13:41 christos Exp $        */
   2 /*      $KAME: if_nameindex.c,v 1.8 2000/11/24 08:20:01 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_nameindex.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_nameindex.c,v 1.7 2012/03/13 21:13:41 christos 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_dl.h>
  38 #include <net/if.h>
  39 #include <ifaddrs.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42
  43 #ifdef __weak_alias
  44 __weak_alias(if_nameindex,_if_nameindex)
  45 __weak_alias(if_freenameindex,_if_freenameindex)
  46 #endif
  47 /*
  48  * From RFC 2553:
  49  *
  50  * 4.3 Return All Interface Names and Indexes
  51  *
  52  *    The if_nameindex structure holds the information about a single
  53  *    interface and is defined as a result of including the <net/if.h>
  54  *    header.
  55  *
  56  *       struct if_nameindex {
  57  *         unsigned int   if_index;
  58  *         char          *if_name;
  59  *       };
  60  *
  61  *    The final function returns an array of if_nameindex structures, one
  62  *    structure per interface.
  63  *
  64  *       struct if_nameindex  *if_nameindex(void);
  65  *
  66  *    The end of the array of structures is indicated by a structure with
  67  *    an if_index of 0 and an if_name of NULL.  The function returns a NULL
  68  *    pointer upon an error, and would set errno to the appropriate value.
  69  *
  70  *    The memory used for this array of structures along with the interface
  71  *    names pointed to by the if_name members is obtained dynamically.
  72  *    This memory is freed by the next function.
  73  *
  74  * 4.4.  Free Memory
  75  *
  76  *    The following function frees the dynamic memory that was allocated by
  77  *    if_nameindex().
  78  *
  79  *        #include <net/if.h>
  80  *
  81  *        void  if_freenameindex(struct if_nameindex *ptr);
  82  *
  83  *    The argument to this function must be a pointer that was returned by
  84  *    if_nameindex().
  85  */
  86
  87 struct if_nameindex *
  88 if_nameindex(void)
  89 {
  90         struct ifaddrs *ifaddrs, *ifa;
  91         size_t nbytes, ni;
  92         struct if_nameindex *ifni, *ifni2;
  93         char *cp;
  94
  95         if (getifaddrs(&ifaddrs) < 0)
  96                 return(NULL);
  97
  98         /*
  99          * First, find out how many interfaces there are, and how
 100          * much space we need for the string names.
 101          */
 102         ni = 0;
 103         nbytes = 0;
 104         for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
 105                 if (ifa->ifa_addr &&
 106                     ifa->ifa_addr->sa_family == AF_LINK) {
 107                         nbytes += strlen(ifa->ifa_name) + 1;
 108                         ni++;
 109                 }
 110         }
 111
 112         /*
 113          * Next, allocate a chunk of memory, use the first part
 114          * for the array of structures, and the last part for
 115          * the strings.
 116          */
 117         cp = malloc((ni + 1) * sizeof(struct if_nameindex) + nbytes);
 118         ifni = (struct if_nameindex *)(void *)cp;
 119         if (ifni == NULL)
 120                 goto out;
 121         cp += (ni + 1) * sizeof(struct if_nameindex);
 122
 123         /*
 124          * Now just loop through the list of interfaces again,
 125          * filling in the if_nameindex array and making copies
 126          * of all the strings.
 127          */
 128         ifni2 = ifni;
 129         for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
 130                 if (ifa->ifa_addr &&
 131                     ifa->ifa_addr->sa_family == AF_LINK) {
 132                         ifni2->if_index =
 133                             ((struct sockaddr_dl*)
 134                             (void *)ifa->ifa_addr)->sdl_index;
 135                         ifni2->if_name = cp;
 136                         strcpy(cp, ifa->ifa_name);
 137                         ifni2++;
 138                         cp += strlen(cp) + 1;
 139                 }
 140         }
 141         /*
 142          * Finally, don't forget to terminate the array.
 143          */
 144         ifni2->if_index = 0;
 145         ifni2->if_name = NULL;
 146 out:
 147         freeifaddrs(ifaddrs);
 148         return(ifni);
 149 }
 150
 151 void
 152 if_freenameindex(struct if_nameindex *ptr)
 153 {
 154         free(ptr);
 155 }