lib/libc/net/if_nameindex.c

   1 /*      $KAME: if_nameindex.c,v 1.8 2000/11/24 08:20:01 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_nameindex.c,v 2.3 2000/04/17 22:38:05 dab Exp
  26  *
  27  * $FreeBSD: src/lib/libc/net/if_nameindex.c,v 1.1.2.1 2002/07/29 18:33:18 ume Exp $
  28  * $DragonFly: src/lib/libc/net/if_nameindex.c,v 1.2 2003/06/17 06:26:44 dillon Exp $
  29  */
  30
  31 #include <sys/types.h>
  32 #include <sys/socket.h>
  33 #include <net/if_dl.h>
  34 #include <net/if.h>
  35 #include <ifaddrs.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38
  39 /*
  40  * From RFC 2553:
  41  *
  42  * 4.3 Return All Interface Names and Indexes
  43  *
  44  *    The if_nameindex structure holds the information about a single
  45  *    interface and is defined as a result of including the <net/if.h>
  46  *    header.
  47  *
  48  *       struct if_nameindex {
  49  *         unsigned int   if_index;
  50  *         char          *if_name;
  51  *       };
  52  *
  53  *    The final function returns an array of if_nameindex structures, one
  54  *    structure per interface.
  55  *
  56  *       struct if_nameindex  *if_nameindex(void);
  57  *
  58  *    The end of the array of structures is indicated by a structure with
  59  *    an if_index of 0 and an if_name of NULL.  The function returns a NULL
  60  *    pointer upon an error, and would set errno to the appropriate value.
  61  *
  62  *    The memory used for this array of structures along with the interface
  63  *    names pointed to by the if_name members is obtained dynamically.
  64  *    This memory is freed by the next function.
  65  *
  66  * 4.4.  Free Memory
  67  *
  68  *    The following function frees the dynamic memory that was allocated by
  69  *    if_nameindex().
  70  *
  71  *        #include <net/if.h>
  72  *
  73  *        void  if_freenameindex(struct if_nameindex *ptr);
  74  *
  75  *    The argument to this function must be a pointer that was returned by
  76  *    if_nameindex().
  77  */
  78
  79 struct if_nameindex *
  80 if_nameindex(void)
  81 {
  82         struct ifaddrs *ifaddrs, *ifa;
  83         unsigned int ni;
  84         int nbytes;
  85         struct if_nameindex *ifni, *ifni2;
  86         char *cp;
  87
  88         if (getifaddrs(&ifaddrs) < 0)
  89                 return(NULL);
  90
  91         /*
  92          * First, find out how many interfaces there are, and how
  93          * much space we need for the string names.
  94          */
  95         ni = 0;
  96         nbytes = 0;
  97         for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
  98                 if (ifa->ifa_addr &&
  99                     ifa->ifa_addr->sa_family == AF_LINK) {
 100                         nbytes += strlen(ifa->ifa_name) + 1;
 101                         ni++;
 102                 }
 103         }
 104
 105         /*
 106          * Next, allocate a chunk of memory, use the first part
 107          * for the array of structures, and the last part for
 108          * the strings.
 109          */
 110         cp = malloc((ni + 1) * sizeof(struct if_nameindex) + nbytes);
 111         ifni = (struct if_nameindex *)cp;
 112         if (ifni == NULL)
 113                 goto out;
 114         cp += (ni + 1) * sizeof(struct if_nameindex);
 115
 116         /*
 117          * Now just loop through the list of interfaces again,
 118          * filling in the if_nameindex array and making copies
 119          * of all the strings.
 120          */
 121         ifni2 = ifni;
 122         for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
 123                 if (ifa->ifa_addr &&
 124                     ifa->ifa_addr->sa_family == AF_LINK) {
 125                         ifni2->if_index =
 126                             ((struct sockaddr_dl*)ifa->ifa_addr)->sdl_index;
 127                         ifni2->if_name = cp;
 128                         strcpy(cp, ifa->ifa_name);
 129                         ifni2++;
 130                         cp += strlen(cp) + 1;
 131                 }
 132         }
 133         /*
 134          * Finally, don't forget to terminate the array.
 135          */
 136         ifni2->if_index = 0;
 137         ifni2->if_name = NULL;
 138 out:
 139         freeifaddrs(ifaddrs);
 140         return(ifni);
 141 }
 142
 143 void
 144 if_freenameindex(struct if_nameindex *ptr)
 145 {
 146         free(ptr);
 147 }