38debe842d1d4fae3ba34609052be8af9ace44a4
[tinc] / 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 const 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(errno == EPERM || errno == EBUSY) {
129                 logger(LOG_ERR, "Error while trying to configure %s: %s", device, strerror(errno));
130                 return false;
131         } else if(!ioctl(device_fd, (('T' << 8) | 202), &ifr)) {
132                 logger(LOG_WARNING, "Old ioctl() request was needed for %s", device);
133                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
134                 ifrname[IFNAMSIZ - 1] = 0;
135                 free(iface);
136                 iface = xstrdup(ifrname);
137         } else
138 #endif
139         {
140                 if(routing_mode == RMODE_ROUTER) {
141                         overwrite_mac = true;
142                 }
143
144                 device_info = "Linux ethertap device";
145                 device_type = DEVICE_TYPE_ETHERTAP;
146                 free(iface);
147                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
148         }
149
150         if(overwrite_mac && !ioctl(device_fd, SIOCGIFHWADDR, &ifr)) {
151                 memcpy(mymac.x, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
152         }
153
154         logger(LOG_INFO, "%s is a %s", device, device_info);
155
156         return true;
157 }
158
159 static void close_device(void) {
160         close(device_fd);
161
162         free(type);
163         free(device);
164         free(iface);
165 }
166
167 static bool read_packet(vpn_packet_t *packet) {
168         int lenin;
169
170         switch(device_type) {
171         case DEVICE_TYPE_TUN:
172                 lenin = read(device_fd, packet->data + 10, MTU - 10);
173
174                 if(lenin <= 0) {
175                         logger(LOG_ERR, "Error while reading from %s %s: %s",
176                                device_info, device, strerror(errno));
177                         return false;
178                 }
179
180                 memset(packet->data, 0, 12);
181                 packet->len = lenin + 10;
182                 break;
183
184         case DEVICE_TYPE_TAP:
185                 lenin = read(device_fd, packet->data, MTU);
186
187                 if(lenin <= 0) {
188                         logger(LOG_ERR, "Error while reading from %s %s: %s",
189                                device_info, device, strerror(errno));
190                         return false;
191                 }
192
193                 packet->len = lenin;
194                 break;
195
196         case DEVICE_TYPE_ETHERTAP:
197                 lenin = read(device_fd, packet->data - 2, MTU + 2);
198
199                 if(lenin <= 0) {
200                         logger(LOG_ERR, "Error while reading from %s %s: %s",
201                                device_info, device, strerror(errno));
202                         return false;
203                 }
204
205                 packet->len = lenin - 2;
206                 break;
207         }
208
209         device_total_in += packet->len;
210
211         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
212                                 device_info);
213
214         return true;
215 }
216
217 static bool write_packet(vpn_packet_t *packet) {
218         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Writing packet of %d bytes to %s",
219                                 packet->len, device_info);
220
221         switch(device_type) {
222         case DEVICE_TYPE_TUN:
223                 packet->data[10] = packet->data[11] = 0;
224
225                 if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
226                         logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
227                                strerror(errno));
228                         return false;
229                 }
230
231                 break;
232
233         case DEVICE_TYPE_TAP:
234                 if(write(device_fd, packet->data, packet->len) < 0) {
235                         logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
236                                strerror(errno));
237                         return false;
238                 }
239
240                 break;
241
242         case DEVICE_TYPE_ETHERTAP:
243                 memcpy(packet->data - 2, &packet->len, 2);
244
245                 if(write(device_fd, packet->data - 2, packet->len + 2) < 0) {
246                         logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
247                                strerror(errno));
248                         return false;
249                 }
250
251                 break;
252         }
253
254         device_total_out += packet->len;
255
256         return true;
257 }
258
259 static void dump_device_stats(void) {
260         logger(LOG_DEBUG, "Statistics for %s %s:", device_info, device);
261         logger(LOG_DEBUG, " total bytes in:  %10"PRIu64, device_total_in);
262         logger(LOG_DEBUG, " total bytes out: %10"PRIu64, device_total_out);
263 }
264
265 const devops_t os_devops = {
266         .setup = setup_device,
267         .close = close_device,
268         .read = read_packet,
269         .write = write_packet,
270         .dump_stats = dump_device_stats,
271 };