Add support for meson build system
[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 #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 "../route.h"
31 #include "../xalloc.h"
32
33 typedef enum device_type_t {
34         DEVICE_TYPE_TUN,
35         DEVICE_TYPE_TAP,
36 } device_type_t;
37
38 int device_fd = -1;
39 static device_type_t device_type;
40 char *device = NULL;
41 char *iface = NULL;
42 static char *type = NULL;
43 static char ifrname[IFNAMSIZ];
44 static const char *device_info;
45
46 static bool setup_device(void) {
47         if(!get_config_string(lookup_config(&config_tree, "Device"), &device)) {
48                 device = xstrdup(DEFAULT_DEVICE);
49         }
50
51         if(!get_config_string(lookup_config(&config_tree, "Interface"), &iface))
52                 if(netname) {
53                         iface = xstrdup(netname);
54                 }
55
56         device_fd = open(device, O_RDWR | O_NONBLOCK);
57
58         if(device_fd < 0) {
59                 logger(DEBUG_ALWAYS, LOG_ERR, "Could not open %s: %s", device, strerror(errno));
60                 return false;
61         }
62
63 #ifdef FD_CLOEXEC
64         fcntl(device_fd, F_SETFD, FD_CLOEXEC);
65 #endif
66
67         struct ifreq ifr = {0};
68
69         get_config_string(lookup_config(&config_tree, "DeviceType"), &type);
70
71         if(type && strcasecmp(type, "tun") && strcasecmp(type, "tap")) {
72                 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown device type %s!", type);
73                 return false;
74         }
75
76         if((type && !strcasecmp(type, "tun")) || (!type && routing_mode == RMODE_ROUTER)) {
77                 ifr.ifr_flags = IFF_TUN;
78                 device_type = DEVICE_TYPE_TUN;
79                 device_info = "Linux tun/tap device (tun mode)";
80         } else {
81                 if(routing_mode == RMODE_ROUTER) {
82                         overwrite_mac = true;
83                 }
84
85                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
86                 device_type = DEVICE_TYPE_TAP;
87                 device_info = "Linux tun/tap device (tap mode)";
88         }
89
90 #ifdef IFF_ONE_QUEUE
91         /* Set IFF_ONE_QUEUE flag... */
92
93         bool t1q = false;
94
95         if(get_config_bool(lookup_config(&config_tree, "IffOneQueue"), &t1q) && t1q) {
96                 ifr.ifr_flags |= IFF_ONE_QUEUE;
97         }
98
99 #endif
100
101         if(iface) {
102                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
103                 ifr.ifr_name[IFNAMSIZ - 1] = 0;
104         }
105
106         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
107                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
108                 ifrname[IFNAMSIZ - 1] = 0;
109                 free(iface);
110                 iface = xstrdup(ifrname);
111         } else {
112                 logger(DEBUG_ALWAYS, LOG_ERR, "Could not create a tun/tap interface from %s: %s", device, strerror(errno));
113                 return false;
114         }
115
116         logger(DEBUG_ALWAYS, LOG_INFO, "%s is a %s", device, device_info);
117
118         if(ifr.ifr_flags & IFF_TAP) {
119                 struct ifreq ifr_mac = {0};
120
121                 if(!ioctl(device_fd, SIOCGIFHWADDR, &ifr_mac)) {
122                         memcpy(mymac.x, ifr_mac.ifr_hwaddr.sa_data, ETH_ALEN);
123                 } else {
124                         logger(DEBUG_ALWAYS, LOG_WARNING, "Could not get MAC address of %s: %s", device, strerror(errno));
125                 }
126         }
127
128         return true;
129 }
130
131 static void close_device(void) {
132         close(device_fd);
133         device_fd = -1;
134
135         free(type);
136         type = NULL;
137         free(device);
138         device = NULL;
139         free(iface);
140         iface = NULL;
141         device_info = NULL;
142 }
143
144 static bool read_packet(vpn_packet_t *packet) {
145         ssize_t inlen;
146
147         switch(device_type) {
148         case DEVICE_TYPE_TUN:
149                 inlen = read(device_fd, DATA(packet) + 10, MTU - 10);
150
151                 if(inlen <= 0) {
152                         logger(DEBUG_ALWAYS, LOG_ERR, "Error while reading from %s %s: %s",
153                                device_info, device, strerror(errno));
154
155                         if(errno == EBADFD) {  /* File descriptor in bad state */
156                                 event_exit();
157                         }
158
159                         return false;
160                 }
161
162                 memset(DATA(packet), 0, 12);
163                 packet->len = inlen + 10;
164                 break;
165
166         case DEVICE_TYPE_TAP:
167                 inlen = read(device_fd, DATA(packet), MTU);
168
169                 if(inlen <= 0) {
170                         logger(DEBUG_ALWAYS, LOG_ERR, "Error while reading from %s %s: %s",
171                                device_info, device, strerror(errno));
172                         return false;
173                 }
174
175                 packet->len = inlen;
176                 break;
177
178         default:
179                 abort();
180         }
181
182         logger(DEBUG_TRAFFIC, LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
183                device_info);
184
185         return true;
186 }
187
188 static bool write_packet(vpn_packet_t *packet) {
189         logger(DEBUG_TRAFFIC, LOG_DEBUG, "Writing packet of %d bytes to %s",
190                packet->len, device_info);
191
192         switch(device_type) {
193         case DEVICE_TYPE_TUN:
194                 DATA(packet)[10] = DATA(packet)[11] = 0;
195
196                 if(write(device_fd, DATA(packet) + 10, packet->len - 10) < 0) {
197                         logger(DEBUG_ALWAYS, LOG_ERR, "Can't write to %s %s: %s", device_info, device,
198                                strerror(errno));
199                         return false;
200                 }
201
202                 break;
203
204         case DEVICE_TYPE_TAP:
205                 if(write(device_fd, DATA(packet), packet->len) < 0) {
206                         logger(DEBUG_ALWAYS, LOG_ERR, "Can't write to %s %s: %s", device_info, device,
207                                strerror(errno));
208                         return false;
209                 }
210
211                 break;
212
213         default:
214                 abort();
215         }
216
217         return true;
218 }
219
220 const devops_t os_devops = {
221         .setup = setup_device,
222         .close = close_device,
223         .read = read_packet,
224         .write = write_packet,
225 };