git.meshlink.io Git - meshlink/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                   2001-2013 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 #include <linux/if_tun.h>
  24 #define DEFAULT_DEVICE "/dev/net/tun"
  25
  26 #include "../conf.h"
  27 #include "../device.h"
  28 #include "../logger.h"
  29 #include "../names.h"
  30 #include "../net.h"
  31 #include "../route.h"
  32 #include "../utils.h"
  33 #include "../xalloc.h"
  34 #include "../device.h"
  35
  36 typedef enum device_type_t {
  37         DEVICE_TYPE_TUN,
  38         DEVICE_TYPE_TAP,
  39 } device_type_t;
  40
  41 int device_fd = -1;
  42 static device_type_t device_type;
  43 char *device = NULL;
  44 char *iface = NULL;
  45 static char *type = NULL;
  46 static char ifrname[IFNAMSIZ];
  47 static char *device_info;
  48
  49 static bool setup_device(void) {
  50         if(!get_config_string(lookup_config(config_tree, "Device"), &device))
  51                 device = xstrdup(DEFAULT_DEVICE);
  52
  53         if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
  54                 if(netname)
  55                         iface = xstrdup(netname);
  56
  57         device_fd = open(device, O_RDWR | O_NONBLOCK);
  58
  59         if(device_fd < 0) {
  60                 logger(DEBUG_ALWAYS, LOG_ERR, "Could not open %s: %s", device, strerror(errno));
  61                 return false;
  62         }
  63
  64 #ifdef FD_CLOEXEC
  65         fcntl(device_fd, F_SETFD, FD_CLOEXEC);
  66 #endif
  67
  68         struct ifreq ifr = {{{0}}};
  69
  70         get_config_string(lookup_config(config_tree, "DeviceType"), &type);
  71
  72         if(type && strcasecmp(type, "tun") && strcasecmp(type, "tap")) {
  73                 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown device type %s!", type);
  74                 return false;
  75         }
  76
  77         if((type && !strcasecmp(type, "tun")) || (!type && 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                 if (routing_mode == RMODE_ROUTER)
  83                         overwrite_mac = true;
  84                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  85                 device_type = DEVICE_TYPE_TAP;
  86                 device_info = "Linux tun/tap device (tap mode)";
  87         }
  88
  89 #ifdef IFF_ONE_QUEUE
  90         /* Set IFF_ONE_QUEUE flag... */
  91
  92         bool t1q = false;
  93         if(get_config_bool(lookup_config(config_tree, "IffOneQueue"), &t1q) && t1q)
  94                 ifr.ifr_flags |= IFF_ONE_QUEUE;
  95 #endif
  96
  97         if(iface)
  98                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
  99
 100         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
 101                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
 102                 free(iface);
 103                 iface = xstrdup(ifrname);
 104         }
 105
 106         logger(DEBUG_ALWAYS, LOG_INFO, "%s is a %s", device, device_info);
 107
 108         return true;
 109 }
 110
 111 static void close_device(void) {
 112         close(device_fd);
 113
 114         free(type);
 115         free(device);
 116         free(iface);
 117 }
 118
 119 static bool read_packet(vpn_packet_t *packet) {
 120         int inlen;
 121
 122         switch(device_type) {
 123                 case DEVICE_TYPE_TUN:
 124                         inlen = read(device_fd, packet->data + 10, MTU - 10);
 125
 126                         if(inlen <= 0) {
 127                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while reading from %s %s: %s",
 128                                            device_info, device, strerror(errno));
 129                                 return false;
 130                         }
 131
 132                         memset(packet->data, 0, 12);
 133                         packet->len = inlen + 10;
 134                         break;
 135                 case DEVICE_TYPE_TAP:
 136                         inlen = read(device_fd, packet->data, MTU);
 137
 138                         if(inlen <= 0) {
 139                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while reading from %s %s: %s",
 140                                            device_info, device, strerror(errno));
 141                                 return false;
 142                         }
 143
 144                         packet->len = inlen;
 145                         break;
 146                 default:
 147                         abort();
 148         }
 149
 150         logger(DEBUG_TRAFFIC, LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
 151                            device_info);
 152
 153         return true;
 154 }
 155
 156 static bool write_packet(vpn_packet_t *packet) {
 157         logger(DEBUG_TRAFFIC, LOG_DEBUG, "Writing packet of %d bytes to %s",
 158                            packet->len, device_info);
 159
 160         switch(device_type) {
 161                 case DEVICE_TYPE_TUN:
 162                         packet->data[10] = packet->data[11] = 0;
 163                         if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
 164                                 logger(DEBUG_ALWAYS, LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 165                                            strerror(errno));
 166                                 return false;
 167                         }
 168                         break;
 169                 case DEVICE_TYPE_TAP:
 170                         if(write(device_fd, packet->data, packet->len) < 0) {
 171                                 logger(DEBUG_ALWAYS, LOG_ERR, "Can't write to %s %s: %s", device_info, device,
 172                                            strerror(errno));
 173                                 return false;
 174                         }
 175                         break;
 176                 default:
 177                         abort();
 178         }
 179
 180         return true;
 181 }
 182
 183 const devops_t os_devops = {
 184         .setup = setup_device,
 185         .close = close_device,
 186         .read = read_packet,
 187         .write = write_packet,
 188 };