f75f4bdb741ca58c5f9b0df32fa7fdf3b71764ef
[oweals/tinc.git] / src / linux / device.c
1 /*
2     device.c -- Interaction with Linux ethertap and tun/tap device
3     Copyright (C) 2001-2005 Ivo Timmermans,
4                   2001-2014 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
63         if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
64 #ifdef HAVE_LINUX_IF_TUN_H
65                 if(netname != NULL) {
66                         iface = xstrdup(netname);
67                 }
68
69 #else
70                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
71 #endif
72         device_fd = open(device, O_RDWR | O_NONBLOCK);
73
74         if(device_fd < 0) {
75                 logger(LOG_ERR, "Could not open %s: %s", device, strerror(errno));
76                 return false;
77         }
78
79 #ifdef FD_CLOEXEC
80         fcntl(device_fd, F_SETFD, FD_CLOEXEC);
81 #endif
82
83 #ifdef HAVE_LINUX_IF_TUN_H
84         /* Ok now check if this is an old ethertap or a new tun/tap thingie */
85
86         memset(&ifr, 0, sizeof(ifr));
87
88         get_config_string(lookup_config(config_tree, "DeviceType"), &type);
89
90         if(type && strcasecmp(type, "tun") && strcasecmp(type, "tap")) {
91                 logger(LOG_ERR, "Unknown device type %s!", type);
92                 return false;
93         }
94
95         if((type && !strcasecmp(type, "tun")) || (!type && routing_mode == RMODE_ROUTER)) {
96                 ifr.ifr_flags = IFF_TUN;
97                 device_type = DEVICE_TYPE_TUN;
98                 device_info = "Linux tun/tap device (tun mode)";
99         } else {
100                 if(routing_mode == RMODE_ROUTER) {
101                         overwrite_mac = true;
102                 }
103
104                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
105                 device_type = DEVICE_TYPE_TAP;
106                 device_info = "Linux tun/tap device (tap mode)";
107         }
108
109 #ifdef IFF_ONE_QUEUE
110
111         /* Set IFF_ONE_QUEUE flag... */
112         if(get_config_bool(lookup_config(config_tree, "IffOneQueue"), &t1q) && t1q) {
113                 ifr.ifr_flags |= IFF_ONE_QUEUE;
114         }
115
116 #endif
117
118         if(iface) {
119                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
120                 ifr.ifr_name[IFNAMSIZ - 1] = 0;
121         }
122
123         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
124                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
125                 ifrname[IFNAMSIZ - 1] = 0;
126                 free(iface);
127                 iface = xstrdup(ifrname);
128         } else if(!ioctl(device_fd, (('T' << 8) | 202), &ifr)) {
129                 logger(LOG_WARNING, "Old ioctl() request was needed for %s", device);
130                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
131                 ifrname[IFNAMSIZ - 1] = 0;
132                 free(iface);
133                 iface = xstrdup(ifrname);
134         } else
135 #endif
136         {
137                 if(routing_mode == RMODE_ROUTER) {
138                         overwrite_mac = true;
139                 }
140
141                 device_info = "Linux ethertap device";
142                 device_type = DEVICE_TYPE_ETHERTAP;
143                 free(iface);
144                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
145         }
146
147         if(overwrite_mac && !ioctl(device_fd, SIOCGIFHWADDR, &ifr)) {
148                 memcpy(mymac.x, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
149         }
150
151         logger(LOG_INFO, "%s is a %s", device, device_info);
152
153         return true;
154 }
155
156 static void close_device(void) {
157         close(device_fd);
158
159         free(type);
160         free(device);
161         free(iface);
162 }
163
164 static bool read_packet(vpn_packet_t *packet) {
165         int lenin;
166
167         switch(device_type) {
168         case DEVICE_TYPE_TUN:
169                 lenin = read(device_fd, packet->data + 10, MTU - 10);
170
171                 if(lenin <= 0) {
172                         logger(LOG_ERR, "Error while reading from %s %s: %s",
173                                device_info, device, strerror(errno));
174                         return false;
175                 }
176
177                 memset(packet->data, 0, 12);
178                 packet->len = lenin + 10;
179                 break;
180
181         case DEVICE_TYPE_TAP:
182                 lenin = read(device_fd, packet->data, MTU);
183
184                 if(lenin <= 0) {
185                         logger(LOG_ERR, "Error while reading from %s %s: %s",
186                                device_info, device, strerror(errno));
187                         return false;
188                 }
189
190                 packet->len = lenin;
191                 break;
192
193         case DEVICE_TYPE_ETHERTAP:
194                 lenin = read(device_fd, packet->data - 2, MTU + 2);
195
196                 if(lenin <= 0) {
197                         logger(LOG_ERR, "Error while reading from %s %s: %s",
198                                device_info, device, strerror(errno));
199                         return false;
200                 }
201
202                 packet->len = lenin - 2;
203                 break;
204         }
205
206         device_total_in += packet->len;
207
208         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
209                                 device_info);
210
211         return true;
212 }
213
214 static bool write_packet(vpn_packet_t *packet) {
215         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Writing packet of %d bytes to %s",
216                                 packet->len, device_info);
217
218         switch(device_type) {
219         case DEVICE_TYPE_TUN:
220                 packet->data[10] = packet->data[11] = 0;
221
222                 if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
223                         logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
224                                strerror(errno));
225                         return false;
226                 }
227
228                 break;
229
230         case DEVICE_TYPE_TAP:
231                 if(write(device_fd, packet->data, packet->len) < 0) {
232                         logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
233                                strerror(errno));
234                         return false;
235                 }
236
237                 break;
238
239         case DEVICE_TYPE_ETHERTAP:
240                 memcpy(packet->data - 2, &packet->len, 2);
241
242                 if(write(device_fd, packet->data - 2, packet->len + 2) < 0) {
243                         logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
244                                strerror(errno));
245                         return false;
246                 }
247
248                 break;
249         }
250
251         device_total_out += packet->len;
252
253         return true;
254 }
255
256 static void dump_device_stats(void) {
257         logger(LOG_DEBUG, "Statistics for %s %s:", device_info, device);
258         logger(LOG_DEBUG, " total bytes in:  %10"PRIu64, device_total_in);
259         logger(LOG_DEBUG, " total bytes out: %10"PRIu64, device_total_out);
260 }
261
262 const devops_t os_devops = {
263         .setup = setup_device,
264         .close = close_device,
265         .read = read_packet,
266         .write = write_packet,
267         .dump_stats = dump_device_stats,
268 };