sysdeps/unix/sysv/linux/if_index.c

   1 /* Copyright (C) 1997 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <string.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <net/if.h>
  23
  24 #define IF_INET6_FILENAME   "/proc/net/if_inet6"
  25
  26 /* /proc/net/if_inet6 contains lines that look like this:
  27  *
  28  * fe8000000000000000000000836fc168 0b 00 20 80     sit7
  29  *
  30  *                               |   |  |  |  |      |
  31  *                     address --'   |  |  |  |      |
  32  *                     index --------'  |  |  |      |
  33  *                     prefix length ---'  |  |      |
  34  *                     scope --------------'  |      |
  35  *                     flags -----------------'      |
  36  *                     name -------------------------'
  37  *
  38  */
  39
  40 static int get_one_interface(FILE *fd, char *interface, int iflen, unsigned int *index)
  41 {
  42   char buffer[80];
  43   static char seps[] = " \012";
  44   char *c = buffer;
  45   char *sp;
  46   if (!fgets(buffer, 80, fd))
  47     return 1;
  48   if (strtok_r(buffer, seps, &sp) == NULL) return 1;
  49   if (c = strtok_r(NULL, seps, &sp), c == NULL) return 1;
  50   *index = strtoul(c, NULL, 16);
  51   if (strtok_r(NULL, seps, &sp) == NULL) return 1;
  52   if (strtok_r(NULL, seps, &sp) == NULL) return 1;
  53   if (strtok_r(NULL, seps, &sp) == NULL) return 1;
  54   if (c = strtok_r(NULL, seps, &sp), c == NULL) return 1;
  55   strncpy(interface, c, iflen);
  56   return 0;
  57 }
  58
  59 unsigned int if_nametoindex(const char *ifname)
  60 {
  61   FILE *fd = fopen(IF_INET6_FILENAME, "r");
  62   char this_ifname[IFNAMSIZ];
  63   unsigned int this_index;
  64   if (!fd) return 0;
  65   while (get_one_interface(fd, this_ifname, IFNAMSIZ, &this_index) == 0) {
  66     if (!strcmp(this_ifname, ifname)) {
  67       fclose(fd);
  68       return this_index;
  69     }
  70   }
  71   fclose(fd);
  72   return 0;
  73 }
  74
  75 char *if_indextoname(unsigned int ifindex, char *ifname)
  76 {
  77   FILE *fd = fopen(IF_INET6_FILENAME, "r");
  78   unsigned int this_index;
  79   if (!fd) return NULL;
  80   while (get_one_interface(fd, ifname, IFNAMSIZ, &this_index) == 0) {
  81     if (this_index == ifindex) {
  82       fclose(fd);
  83       return ifname;
  84     }
  85   }
  86   fclose(fd);
  87   return NULL;
  88 }
  89
  90 void if_freenameindex(struct if_nameindex *ifn)
  91 {
  92   struct if_nameindex *ptr = ifn;
  93   while (ptr->if_name || ptr->if_index)
  94     {
  95       if (ptr->if_name)
  96         free(ptr->if_name);
  97       ptr++;
  98     }
  99   free(ifn);
 100 }
 101
 102 struct if_nameindex *if_nameindex(void)
 103 {
 104   FILE *fd = fopen(IF_INET6_FILENAME, "r");
 105   struct if_nameindex *ifn = NULL;
 106   int nifs = 0;
 107   if (!fd) return NULL;
 108   do
 109     {
 110       struct if_nameindex *newifn;
 111       nifs++;
 112       newifn = realloc(ifn, nifs*sizeof(struct if_nameindex));
 113       if (!newifn)
 114         {
 115           /* We ran out of memory. */
 116           if (--nifs)
 117             {
 118               free(ifn[nifs-1].if_name);
 119               ifn[nifs-1].if_name = 0;
 120               ifn[nifs-1].if_index = 0;
 121               if_freenameindex(ifn);
 122             }
 123           return NULL;
 124         }
 125       ifn = newifn;
 126       ifn[nifs-1].if_index = 0;
 127       ifn[nifs-1].if_name = malloc(IFNAMSIZ);
 128       if (ifn[nifs-1].if_name == NULL)
 129         {
 130           if_freenameindex(ifn);
 131           return NULL;
 132         }
 133     }
 134   while (get_one_interface(fd, ifn[nifs-1].if_name, IFNAMSIZ,
 135                            &ifn[nifs-1].if_index) == 0);
 136   free(ifn[nifs-1].if_name);
 137   ifn[nifs-1].if_name = NULL;
 138   fclose(fd);
 139   return ifn;
 140 }