src/linux/device.c

   1 /*
   2     device.c -- Interaction with Linux ethertap and tun/tap device
   3     Copyright (C) 2001-2005 Ivo Timmermans,
   4                   2001-2009 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 "logger.h"
  32 #include "net.h"
  33 #include "route.h"
  34 #include "utils.h"
  35 #include "xalloc.h"
  36
  37 typedef enum device_type_t {
  38         DEVICE_TYPE_ETHERTAP,
  39         DEVICE_TYPE_TUN,
  40         DEVICE_TYPE_TAP,
  41 } device_type_t;
  42
  43 int device_fd = -1;
  44 static device_type_t device_type;
  45 char *device = NULL;
  46 char *iface = NULL;
  47 static char ifrname[IFNAMSIZ];
  48 static char *device_info;
  49
  50 static int device_total_in = 0;
  51 static int device_total_out = 0;
  52
  53 bool setup_device(void) {
  54         struct ifreq ifr;
  55
  56         if(!get_config_string(lookup_config(config_tree, "Device"), &device))
  57                 device = xstrdup(DEFAULT_DEVICE);
  58
  59         if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
  60 #ifdef HAVE_LINUX_IF_TUN_H
  61                 if (netname != NULL)
  62                         iface = xstrdup(netname);
  63 #else
  64                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
  65 #endif
  66         device_fd = open(device, O_RDWR | O_NONBLOCK);
  67
  68         if(device_fd < 0) {
  69                 logger(LOG_ERR, "Could not open %s: %s", device, strerror(errno));
  70                 return false;
  71         }
  72
  73 #ifdef HAVE_LINUX_IF_TUN_H
  74         /* Ok now check if this is an old ethertap or a new tun/tap thingie */
  75
  76         memset(&ifr, 0, sizeof(ifr));
  77         if(routing_mode == RMODE_ROUTER) {
  78                 ifr.ifr_flags = IFF_TUN;
  79                 device_type = DEVICE_TYPE_TUN;
  80                 device_info = "Linux tun/tap device (tun mode)";
  81         } else {
  82                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  83                 device_type = DEVICE_TYPE_TAP;
  84                 device_info = "Linux tun/tap device (tap mode)";
  85         }
  86
  87         if(iface)
  88                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
  89
  90         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
  91                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
  92                 if(iface) free(iface);
  93                 iface = xstrdup(ifrname);
  94         } else if(!ioctl(device_fd, (('T' << 8) | 202), &ifr)) {
  95                 logger(LOG_WARNING, "Old ioctl() request was needed for %s", device);
  96                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
  97                 if(iface) free(iface);
  98                 iface = xstrdup(ifrname);
  99         } else
 100 #endif
 101         {
 102                 if(routing_mode == RMODE_ROUTER)
 103                         overwrite_mac = true;
 104                 device_info = "Linux ethertap device";
 105                 device_type = DEVICE_TYPE_ETHERTAP;
 106                 if(iface)
 107                         free(iface);
 108                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
 109         }
 110
 111         logger(LOG_INFO, "%s is a %s", device, device_info);
 112
 113         return true;
 114 }
 115
 116 void close_device(void) {
 117         close(device_fd);
 118
 119         free(device);
 120         free(iface);
 121 }
 122
 123 bool read_packet(vpn_packet_t *packet) {
 124         int lenin;
 125
 126         switch(device_type) {
 127                 case DEVICE_TYPE_TUN:
 128                         lenin = read(device_fd, packet->data + 10, MTU - 10);
 129
 130                         if(lenin <= 0) {
 131                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
 132                                            device_info, device, strerror(errno));
 133                                 return false;
 134                         }
 135
 136                         packet->len = lenin + 10;
 137                         break;
 138                 case DEVICE_TYPE_TAP:
 139                         lenin = read(device_fd, packet->data, MTU);
 140
 141                         if(lenin <= 0) {
 142                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
 143                                            device_info, device, strerror(errno));
 144                                 return false;
 145                         }
 146
 147                         packet->len = lenin;
 148                         break;
 149                 case DEVICE_TYPE_ETHERTAP:
 150                         lenin = read(device_fd, packet->data - 2, MTU + 2);
 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                         packet->len = lenin - 2;
 159                         break;
 160         }
 161
 162         device_total_in += packet->len;
 163
 164         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
 165                            device_info);
 166
 167         return true;
 168 }
 169
 170 bool write_packet(vpn_packet_t *packet) {
 171         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Writing packet of %d bytes to %s",
 172                            packet->len, device_info);
 173
 174         switch(device_type) {
 175                 case DEVICE_TYPE_TUN:
 176                         packet->data[10] = packet->data[11] = 0;
 177                         if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
 178                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 179                                            strerror(errno));
 180                                 return false;
 181                         }
 182                         break;
 183                 case DEVICE_TYPE_TAP:
 184                         if(write(device_fd, packet->data, packet->len) < 0) {
 185                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 186                                            strerror(errno));
 187                                 return false;
 188                         }
 189                         break;
 190                 case DEVICE_TYPE_ETHERTAP:
 191                         *(short int *)(packet->data - 2) = packet->len;
 192
 193                         if(write(device_fd, packet->data - 2, packet->len + 2) < 0) {
 194                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 195                                            strerror(errno));
 196                                 return false;
 197                         }
 198                         break;
 199         }
 200
 201         device_total_out += packet->len;
 202
 203         return true;
 204 }
 205
 206 void dump_device_stats(void) {
 207         logger(LOG_DEBUG, "Statistics for %s %s:", device_info, device);
 208         logger(LOG_DEBUG, " total bytes in:  %10d", device_total_in);
 209         logger(LOG_DEBUG, " total bytes out: %10d", device_total_out);
 210 }