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 *type = NULL;
  49 static char ifrname[IFNAMSIZ];
  50 static char *device_info;
  51
  52 static uint64_t device_total_in = 0;
  53 static uint64_t device_total_out = 0;
  54
  55 static bool setup_device(void) {
  56         struct ifreq ifr;
  57         bool t1q = false;
  58
  59         if(!get_config_string(lookup_config(config_tree, "Device"), &device))
  60                 device = xstrdup(DEFAULT_DEVICE);
  61
  62         if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
  63 #ifdef HAVE_LINUX_IF_TUN_H
  64                 if (netname != NULL)
  65                         iface = xstrdup(netname);
  66 #else
  67                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
  68 #endif
  69         device_fd = open(device, O_RDWR | O_NONBLOCK);
  70
  71         if(device_fd < 0) {
  72                 logger(LOG_ERR, "Could not open %s: %s", device, strerror(errno));
  73                 return false;
  74         }
  75
  76 #ifdef FD_CLOEXEC
  77         fcntl(device_fd, F_SETFD, FD_CLOEXEC);
  78 #endif
  79
  80 #ifdef HAVE_LINUX_IF_TUN_H
  81         /* Ok now check if this is an old ethertap or a new tun/tap thingie */
  82
  83         memset(&ifr, 0, sizeof(ifr));
  84
  85         get_config_string(lookup_config(config_tree, "DeviceType"), &type);
  86
  87         if(type && strcasecmp(type, "tun") && strcasecmp(type, "tap")) {
  88                 logger(LOG_ERR, "Unknown device type %s!", type);
  89                 return false;
  90         }
  91
  92         if((type && !strcasecmp(type, "tun")) || (!type && routing_mode == RMODE_ROUTER)) {
  93                 ifr.ifr_flags = IFF_TUN;
  94                 device_type = DEVICE_TYPE_TUN;
  95                 device_info = "Linux tun/tap device (tun mode)";
  96         } else {
  97                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  98                 device_type = DEVICE_TYPE_TAP;
  99                 device_info = "Linux tun/tap device (tap mode)";
 100         }
 101
 102 #ifdef IFF_ONE_QUEUE
 103         /* Set IFF_ONE_QUEUE flag... */
 104         if(get_config_bool(lookup_config(config_tree, "IffOneQueue"), &t1q) && t1q)
 105                 ifr.ifr_flags |= IFF_ONE_QUEUE;
 106 #endif
 107
 108         if(iface)
 109                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
 110
 111         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
 112                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
 113                 if(iface) free(iface);
 114                 iface = xstrdup(ifrname);
 115         } else if(!ioctl(device_fd, (('T' << 8) | 202), &ifr)) {
 116                 logger(LOG_WARNING, "Old ioctl() request was needed for %s", device);
 117                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
 118                 if(iface) free(iface);
 119                 iface = xstrdup(ifrname);
 120         } else
 121 #endif
 122         {
 123                 if(routing_mode == RMODE_ROUTER)
 124                         overwrite_mac = true;
 125                 device_info = "Linux ethertap device";
 126                 device_type = DEVICE_TYPE_ETHERTAP;
 127                 if(iface)
 128                         free(iface);
 129                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
 130         }
 131
 132         logger(LOG_INFO, "%s is a %s", device, device_info);
 133
 134         return true;
 135 }
 136
 137 static void close_device(void) {
 138         close(device_fd);
 139
 140         free(type);
 141         free(device);
 142         free(iface);
 143 }
 144
 145 static bool read_packet(vpn_packet_t *packet) {
 146         int lenin;
 147
 148         switch(device_type) {
 149                 case DEVICE_TYPE_TUN:
 150                         lenin = read(device_fd, packet->data + 10, MTU - 10);
 151
 152                         if(lenin <= 0) {
 153                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
 154                                            device_info, device, strerror(errno));
 155                                 return false;
 156                         }
 157
 158                         memset(packet->data, 0, 12);
 159                         packet->len = lenin + 10;
 160                         break;
 161                 case DEVICE_TYPE_TAP:
 162                         lenin = read(device_fd, packet->data, MTU);
 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;
 171                         break;
 172                 case DEVICE_TYPE_ETHERTAP:
 173                         lenin = read(device_fd, packet->data - 2, MTU + 2);
 174
 175                         if(lenin <= 0) {
 176                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
 177                                            device_info, device, strerror(errno));
 178                                 return false;
 179                         }
 180
 181                         packet->len = lenin - 2;
 182                         break;
 183         }
 184
 185         device_total_in += packet->len;
 186
 187         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
 188                            device_info);
 189
 190         return true;
 191 }
 192
 193 static bool write_packet(vpn_packet_t *packet) {
 194         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Writing packet of %d bytes to %s",
 195                            packet->len, device_info);
 196
 197         switch(device_type) {
 198                 case DEVICE_TYPE_TUN:
 199                         packet->data[10] = packet->data[11] = 0;
 200                         if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
 201                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 202                                            strerror(errno));
 203                                 return false;
 204                         }
 205                         break;
 206                 case DEVICE_TYPE_TAP:
 207                         if(write(device_fd, packet->data, packet->len) < 0) {
 208                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 209                                            strerror(errno));
 210                                 return false;
 211                         }
 212                         break;
 213                 case DEVICE_TYPE_ETHERTAP:
 214                         memcpy(packet->data - 2, &packet->len, 2);
 215
 216                         if(write(device_fd, packet->data - 2, packet->len + 2) < 0) {
 217                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 218                                            strerror(errno));
 219                                 return false;
 220                         }
 221                         break;
 222         }
 223
 224         device_total_out += packet->len;
 225
 226         return true;
 227 }
 228
 229 static void dump_device_stats(void) {
 230         logger(LOG_DEBUG, "Statistics for %s %s:", device_info, device);
 231         logger(LOG_DEBUG, " total bytes in:  %10"PRIu64, device_total_in);
 232         logger(LOG_DEBUG, " total bytes out: %10"PRIu64, device_total_out);
 233 }
 234
 235 const devops_t os_devops = {
 236         .setup = setup_device,
 237         .close = close_device,
 238         .read = read_packet,
 239         .write = write_packet,
 240         .dump_stats = dump_device_stats,
 241 };