tinc-vpn.org Git - tinc/blob - src/linux/device.c

   1 /*
   2     device.c -- Interaction with Linux ethertap and tun/tap device
   3     Copyright (C) 2001-2005 Ivo Timmermans,
   4                   2001-2012 Guus Sliepen <guus@tinc-vpn.org>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License along
  17     with this program; if not, write to the Free Software Foundation, Inc.,
  18     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19 */
  20
  21 #include "system.h"
  22
  23 #ifdef HAVE_LINUX_IF_TUN_H
  24 #include <linux/if_tun.h>
  25 #define DEFAULT_DEVICE "/dev/net/tun"
  26 #else
  27 #define DEFAULT_DEVICE "/dev/tap0"
  28 #endif
  29
  30 #include "conf.h"
  31 #include "device.h"
  32 #include "logger.h"
  33 #include "net.h"
  34 #include "route.h"
  35 #include "utils.h"
  36 #include "xalloc.h"
  37
  38 typedef enum device_type_t {
  39         DEVICE_TYPE_ETHERTAP,
  40         DEVICE_TYPE_TUN,
  41         DEVICE_TYPE_TAP,
  42 } device_type_t;
  43
  44 int device_fd = -1;
  45 static device_type_t device_type;
  46 char *device = NULL;
  47 char *iface = NULL;
  48 static char ifrname[IFNAMSIZ];
  49 static char *device_info;
  50
  51 static uint64_t device_total_in = 0;
  52 static uint64_t device_total_out = 0;
  53
  54 static bool setup_device(void) {
  55         struct ifreq ifr;
  56         bool t1q = false;
  57
  58         if(!get_config_string(lookup_config(config_tree, "Device"), &device))
  59                 device = xstrdup(DEFAULT_DEVICE);
  60
  61         if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
  62 #ifdef HAVE_LINUX_IF_TUN_H
  63                 if (netname != NULL)
  64                         iface = xstrdup(netname);
  65 #else
  66                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
  67 #endif
  68         device_fd = open(device, O_RDWR | O_NONBLOCK);
  69
  70         if(device_fd < 0) {
  71                 logger(LOG_ERR, "Could not open %s: %s", device, strerror(errno));
  72                 return false;
  73         }
  74
  75 #ifdef FD_CLOEXEC
  76         fcntl(device_fd, F_SETFD, FD_CLOEXEC);
  77 #endif
  78
  79 #ifdef HAVE_LINUX_IF_TUN_H
  80         /* Ok now check if this is an old ethertap or a new tun/tap thingie */
  81
  82         memset(&ifr, 0, sizeof(ifr));
  83         if(routing_mode == RMODE_ROUTER) {
  84                 ifr.ifr_flags = IFF_TUN;
  85                 device_type = DEVICE_TYPE_TUN;
  86                 device_info = "Linux tun/tap device (tun mode)";
  87         } else {
  88                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  89                 device_type = DEVICE_TYPE_TAP;
  90                 device_info = "Linux tun/tap device (tap mode)";
  91         }
  92
  93 #ifdef IFF_ONE_QUEUE
  94         /* Set IFF_ONE_QUEUE flag... */
  95         if(get_config_bool(lookup_config(config_tree, "IffOneQueue"), &t1q) && t1q)
  96                 ifr.ifr_flags |= IFF_ONE_QUEUE;
  97 #endif
  98
  99         if(iface)
 100                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
 101
 102         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
 103                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
 104                 if(iface) free(iface);
 105                 iface = xstrdup(ifrname);
 106         } else if(!ioctl(device_fd, (('T' << 8) | 202), &ifr)) {
 107                 logger(LOG_WARNING, "Old ioctl() request was needed for %s", device);
 108                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
 109                 if(iface) free(iface);
 110                 iface = xstrdup(ifrname);
 111         } else
 112 #endif
 113         {
 114                 if(routing_mode == RMODE_ROUTER)
 115                         overwrite_mac = true;
 116                 device_info = "Linux ethertap device";
 117                 device_type = DEVICE_TYPE_ETHERTAP;
 118                 if(iface)
 119                         free(iface);
 120                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
 121         }
 122
 123         logger(LOG_INFO, "%s is a %s", device, device_info);
 124
 125         return true;
 126 }
 127
 128 static void close_device(void) {
 129         close(device_fd);
 130
 131         free(device);
 132         free(iface);
 133 }
 134
 135 static bool read_packet(vpn_packet_t *packet) {
 136         int lenin;
 137
 138         switch(device_type) {
 139                 case DEVICE_TYPE_TUN:
 140                         lenin = read(device_fd, packet->data + 10, MTU - 10);
 141
 142                         if(lenin <= 0) {
 143                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
 144                                            device_info, device, strerror(errno));
 145                                 return false;
 146                         }
 147
 148                         packet->len = lenin + 10;
 149                         break;
 150                 case DEVICE_TYPE_TAP:
 151                         lenin = read(device_fd, packet->data, MTU);
 152
 153                         if(lenin <= 0) {
 154                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
 155                                            device_info, device, strerror(errno));
 156                                 return false;
 157                         }
 158
 159                         packet->len = lenin;
 160                         break;
 161                 case DEVICE_TYPE_ETHERTAP:
 162                         lenin = read(device_fd, packet->data - 2, MTU + 2);
 163
 164                         if(lenin <= 0) {
 165                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
 166                                            device_info, device, strerror(errno));
 167                                 return false;
 168                         }
 169
 170                         packet->len = lenin - 2;
 171                         break;
 172         }
 173
 174         device_total_in += packet->len;
 175
 176         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
 177                            device_info);
 178
 179         return true;
 180 }
 181
 182 static bool write_packet(vpn_packet_t *packet) {
 183         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Writing packet of %d bytes to %s",
 184                            packet->len, device_info);
 185
 186         switch(device_type) {
 187                 case DEVICE_TYPE_TUN:
 188                         packet->data[10] = packet->data[11] = 0;
 189                         if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
 190                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 191                                            strerror(errno));
 192                                 return false;
 193                         }
 194                         break;
 195                 case DEVICE_TYPE_TAP:
 196                         if(write(device_fd, packet->data, packet->len) < 0) {
 197                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 198                                            strerror(errno));
 199                                 return false;
 200                         }
 201                         break;
 202                 case DEVICE_TYPE_ETHERTAP:
 203                         *(short int *)(packet->data - 2) = packet->len;
 204
 205                         if(write(device_fd, packet->data - 2, packet->len + 2) < 0) {
 206                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 207                                            strerror(errno));
 208                                 return false;
 209                         }
 210                         break;
 211         }
 212
 213         device_total_out += packet->len;
 214
 215         return true;
 216 }
 217
 218 static void dump_device_stats(void) {
 219         logger(LOG_DEBUG, "Statistics for %s %s:", device_info, device);
 220         logger(LOG_DEBUG, " total bytes in:  %10"PRIu64, device_total_in);
 221         logger(LOG_DEBUG, " total bytes out: %10"PRIu64, device_total_out);
 222 }
 223
 224 const devops_t os_devops = {
 225         .setup = setup_device,
 226         .close = close_device,
 227         .read = read_packet,
 228         .write = write_packet,
 229         .dump_stats = dump_device_stats,
 230 };