networking/tunctl.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * tun devices controller
   4  *
   5  * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
   6  *
   7  * Original code:
   8  *      Jeff Dike
   9  *
  10  * Licensed under GPLv2, see file LICENSE in this source tree.
  11  */
  12
  13 //usage:#define tunctl_trivial_usage
  14 //usage:       "[-f device] ([-t name] | -d name)" IF_FEATURE_TUNCTL_UG(" [-u owner] [-g group] [-b]")
  15 //usage:#define tunctl_full_usage "\n\n"
  16 //usage:       "Create or delete tun interfaces\n"
  17 //usage:     "\nOptions:"
  18 //usage:     "\n        -f name         tun device (/dev/net/tun)"
  19 //usage:     "\n        -t name         Create iface 'name'"
  20 //usage:     "\n        -d name         Delete iface 'name'"
  21 //usage:        IF_FEATURE_TUNCTL_UG(
  22 //usage:     "\n        -u owner        Set iface owner"
  23 //usage:     "\n        -g group        Set iface group"
  24 //usage:     "\n        -b              Brief output"
  25 //usage:        )
  26 //usage:
  27 //usage:#define tunctl_example_usage
  28 //usage:       "# tunctl\n"
  29 //usage:       "# tunctl -d tun0\n"
  30
  31 #include <netinet/in.h>
  32 #include <net/if.h>
  33 #include <linux/if_tun.h>
  34 #include "libbb.h"
  35
  36 /* TUNSETGROUP appeared in 2.6.23 */
  37 #ifndef TUNSETGROUP
  38 #define TUNSETGROUP _IOW('T', 206, int)
  39 #endif
  40
  41 #define IOCTL(a, b, c) ioctl_or_perror_and_die(a, b, c, NULL)
  42
  43 #if 1
  44
  45 int tunctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  46 int tunctl_main(int argc UNUSED_PARAM, char **argv)
  47 {
  48         struct ifreq ifr;
  49         int fd;
  50         const char *opt_name = "tap%d";
  51         const char *opt_device = "/dev/net/tun";
  52 #if ENABLE_FEATURE_TUNCTL_UG
  53         const char *opt_user, *opt_group;
  54         long user = -1, group = -1;
  55 #endif
  56         unsigned opts;
  57
  58         enum {
  59                 OPT_f = 1 << 0, // control device name (/dev/net/tun)
  60                 OPT_t = 1 << 1, // create named interface
  61                 OPT_d = 1 << 2, // delete named interface
  62 #if ENABLE_FEATURE_TUNCTL_UG
  63                 OPT_u = 1 << 3, // set new interface owner
  64                 OPT_g = 1 << 4, // set new interface group
  65                 OPT_b = 1 << 5, // brief output
  66 #endif
  67         };
  68
  69         opt_complementary = "=0:t--d:d--t"; // no arguments; t ^ d
  70         opts = getopt32(argv, "f:t:d:" IF_FEATURE_TUNCTL_UG("u:g:b"),
  71                         &opt_device, &opt_name, &opt_name
  72                         IF_FEATURE_TUNCTL_UG(, &opt_user, &opt_group));
  73
  74         // select device
  75         memset(&ifr, 0, sizeof(ifr));
  76         ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  77         strncpy_IFNAMSIZ(ifr.ifr_name, opt_name);
  78
  79         // open device
  80         fd = xopen(opt_device, O_RDWR);
  81         IOCTL(fd, TUNSETIFF, (void *)&ifr);
  82
  83         // delete?
  84         if (opts & OPT_d) {
  85                 IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)0);
  86                 bb_info_msg("Set '%s' %spersistent", ifr.ifr_name, "non");
  87                 return EXIT_SUCCESS;
  88         }
  89
  90         // create
  91 #if ENABLE_FEATURE_TUNCTL_UG
  92         if (opts & OPT_g) {
  93                 group = xgroup2gid(opt_group);
  94                 IOCTL(fd, TUNSETGROUP, (void *)(uintptr_t)group);
  95         } else
  96                 user = geteuid();
  97         if (opts & OPT_u)
  98                 user = xuname2uid(opt_user);
  99         IOCTL(fd, TUNSETOWNER, (void *)(uintptr_t)user);
 100 #endif
 101         IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)1);
 102
 103         // show info
 104 #if ENABLE_FEATURE_TUNCTL_UG
 105         if (opts & OPT_b) {
 106                 puts(ifr.ifr_name);
 107         } else {
 108                 printf("Set '%s' %spersistent", ifr.ifr_name, "");
 109                 printf(" and owned by uid %ld", user);
 110                 if (group != -1)
 111                         printf(" gid %ld", group);
 112                 bb_putchar('\n');
 113         }
 114 #else
 115         puts(ifr.ifr_name);
 116 #endif
 117         return EXIT_SUCCESS;
 118 }
 119
 120 #else
 121
 122 /* -210 bytes: */
 123
 124 int tunctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 125 int tunctl_main(int argc UNUSED_PARAM, char **argv)
 126 {
 127         struct ifreq ifr;
 128         int fd;
 129         const char *opt_name = "tap%d";
 130         const char *opt_device = "/dev/net/tun";
 131         unsigned opts;
 132
 133         enum {
 134                 OPT_f = 1 << 0, // control device name (/dev/net/tun)
 135                 OPT_t = 1 << 1, // create named interface
 136                 OPT_d = 1 << 2, // delete named interface
 137         };
 138
 139         opt_complementary = "=0:t--d:d--t"; // no arguments; t ^ d
 140         opts = getopt32(argv, "f:t:d:u:g:b", // u, g, b accepted and ignored
 141                         &opt_device, &opt_name, &opt_name, NULL, NULL);
 142
 143         // set interface name
 144         memset(&ifr, 0, sizeof(ifr));
 145         ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
 146         strncpy_IFNAMSIZ(ifr.ifr_name, opt_name);
 147
 148         // open device
 149         fd = xopen(opt_device, O_RDWR);
 150         IOCTL(fd, TUNSETIFF, (void *)&ifr);
 151
 152         // create or delete interface
 153         IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)(0 == (opts & OPT_d)));
 154
 155         return EXIT_SUCCESS;
 156 }
 157
 158 #endif