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 #include <os/overflow.h>
  36 #include <sys/errno.h>
  37
  38 /*
  39  * From RFC 2553:
  40  *
  41  * 4.3 Return All Interface Names and Indexes
  42  *
  43  *    The if_nameindex structure holds the information about a single
  44  *    interface and is defined as a result of including the <net/if.h>
  45  *    header.
  46  *
  47  *       struct if_nameindex {
  48  *         unsigned int   if_index;
  49  *         char          *if_name;
  50  *       };
  51  *
  52  *    The final function returns an array of if_nameindex structures, one
  53  *    structure per interface.
  54  *
  55  *       struct if_nameindex  *if_nameindex(void);
  56  *
  57  *    The end of the array of structures is indicated by a structure with
  58  *    an if_index of 0 and an if_name of NULL.  The function returns a NULL
  59  *    pointer upon an error, and would set errno to the appropriate value.
  60  *
  61  *    The memory used for this array of structures along with the interface
  62  *    names pointed to by the if_name members is obtained dynamically.
  63  *    This memory is freed by the next function.
  64  *
  65  * 4.4.  Free Memory
  66  *
  67  *    The following function frees the dynamic memory that was allocated by
  68  *    if_nameindex().
  69  *
  70  *        #include <net/if.h>
  71  *
  72  *        void  if_freenameindex(struct if_nameindex *ptr);
  73  *
  74  *    The argument to this function must be a pointer that was returned by
  75  *    if_nameindex().
  76  */
  77
  78 struct if_nameindex *
  79 if_nameindex(void)
  80 {
  81         struct ifaddrs *ifaddrs, *ifa;
  82         unsigned int ni;
  83         size_t nbytes;
  84         struct if_nameindex *ifni= NULL, *ifni2;
  85         char *cp;
  86         size_t cpsz;
  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                         /*
 101                          * Security Check: Verify nbytes and ni do not overflow
 102                          */
 103                         if (os_add_overflow(nbytes, strlen(ifa->ifa_name) + 1, &nbytes) ||
 104                                 os_add_overflow(ni, 1, &ni)) {
 105                                 errno = EOVERFLOW;
 106                                 goto out;
 107                         }
 108                 }
 109         }
 110
 111         /*
 112          * Security Check: Verify cpsz does not overflow in next 3 operations
 113          */
 114         if (os_add_overflow(ni, 1, &cpsz)) {
 115                 errno = EOVERFLOW;
 116                 goto out;
 117         }
 118         if (os_mul_overflow(cpsz, sizeof(struct if_nameindex), &cpsz)) {
 119                 errno = EOVERFLOW;
 120                 goto out;
 121         }
 122         if (os_add_overflow(cpsz, nbytes, &cpsz)) {
 123                 errno = EOVERFLOW;
 124                 goto out;
 125         }
 126         /*
 127          * Next, allocate a chunk of memory, use the first part
 128          * for the array of structures, and the last part for
 129          * the strings.
 130          */
 131         cp = malloc(cpsz);
 132         ifni = (struct if_nameindex *)cp;
 133         if (ifni == NULL)
 134                 goto out;
 135         cp += (ni + 1) * sizeof(struct if_nameindex);
 136
 137         /*
 138          * Now just loop through the list of interfaces again,
 139          * filling in the if_nameindex array and making copies
 140          * of all the strings.
 141          */
 142         ifni2 = ifni;
 143         for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
 144                 if (ifa->ifa_addr &&
 145                     ifa->ifa_addr->sa_family == AF_LINK) {
 146                         ifni2->if_index =
 147                             ((struct sockaddr_dl*)ifa->ifa_addr)->sdl_index;
 148                         ifni2->if_name = cp;
 149                         strcpy(cp, ifa->ifa_name);
 150                         ifni2++;
 151                         cp += strlen(cp) + 1;
 152                 }
 153         }
 154         /*
 155          * Finally, don't forget to terminate the array.
 156          */
 157         ifni2->if_index = 0;
 158         ifni2->if_name = NULL;
 159 out:
 160         freeifaddrs(ifaddrs);
 161         return(ifni);
 162 }
 163
 164 #ifndef __OpenBSD__
 165 void
 166 if_freenameindex(struct if_nameindex *ptr)
 167 {
 168         free(ptr);
 169 }
 170 #endif