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