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1 /*
2     device.c -- Interaction with Linux ethertap and tun/tap device
3     Copyright (C) 2001-2005 Ivo Timmermans,
4                   2001-2012 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 "net.h"
30 #include "route.h"
31 #include "utils.h"
32 #include "xalloc.h"
33 #include "device.h"
34
35 typedef enum device_type_t {
36         DEVICE_TYPE_TUN,
37         DEVICE_TYPE_TAP,
38 } device_type_t;
39
40 int device_fd = -1;
41 static device_type_t device_type;
42 char *device = NULL;
43 char *iface = NULL;
44 static char *type = NULL;
45 static char ifrname[IFNAMSIZ];
46 static char *device_info;
47
48 uint64_t device_in_packets = 0;
49 uint64_t device_in_bytes = 0;
50 uint64_t device_out_packets = 0;
51 uint64_t device_out_bytes = 0;
52
53 static bool setup_device(void) {
54         if(!get_config_string(lookup_config(config_tree, "Device"), &device))
55                 device = xstrdup(DEFAULT_DEVICE);
56
57         if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
58 #ifdef HAVE_LINUX_IF_TUN_H
59                 if (netname != NULL)
60                         iface = xstrdup(netname);
61 #else
62                 iface = xstrdup(strrchr(device, '/') ? strrchr(device, '/') + 1 : device);
63 #endif
64         device_fd = open(device, O_RDWR | O_NONBLOCK);
65
66         if(device_fd < 0) {
67                 logger(LOG_ERR, "Could not open %s: %s", device, strerror(errno));
68                 return false;
69         }
70
71 #ifdef FD_CLOEXEC
72         fcntl(device_fd, F_SETFD, FD_CLOEXEC);
73 #endif
74
75         struct ifreq ifr = {{{0}}};
76
77         get_config_string(lookup_config(config_tree, "DeviceType"), &type);
78
79         if(type && strcasecmp(type, "tun") && strcasecmp(type, "tap")) {
80                 logger(LOG_ERR, "Unknown device type %s!", type);
81                 return false;
82         }
83
84         if((type && !strcasecmp(type, "tun")) || (!type && routing_mode == RMODE_ROUTER)) {
85                 ifr.ifr_flags = IFF_TUN;
86                 device_type = DEVICE_TYPE_TUN;
87                 device_info = "Linux tun/tap device (tun mode)";
88         } else {
89                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
90                 device_type = DEVICE_TYPE_TAP;
91                 device_info = "Linux tun/tap device (tap mode)";
92         }
93
94 #ifdef IFF_ONE_QUEUE
95         /* Set IFF_ONE_QUEUE flag... */
96
97         bool t1q = false;
98         if(get_config_bool(lookup_config(config_tree, "IffOneQueue"), &t1q) && t1q)
99                 ifr.ifr_flags |= IFF_ONE_QUEUE;
100 #endif
101
102         if(iface)
103                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
104
105         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
106                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
107                 if(iface) free(iface);
108                 iface = xstrdup(ifrname);
109         } else if(!ioctl(device_fd, (('T' << 8) | 202), &ifr)) {
110                 logger(LOG_WARNING, "Old ioctl() request was needed for %s", device);
111                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
112                 if(iface) free(iface);
113                 iface = xstrdup(ifrname);
114         }
115
116         logger(LOG_INFO, "%s is a %s", device, device_info);
117
118         return true;
119 }
120
121 static void close_device(void) {
122         close(device_fd);
123
124         free(type);
125         free(device);
126         free(iface);
127 }
128
129 static bool read_packet(vpn_packet_t *packet) {
130         int inlen;
131         
132         switch(device_type) {
133                 case DEVICE_TYPE_TUN:
134                         inlen = read(device_fd, packet->data + 10, MTU - 10);
135
136                         if(inlen <= 0) {
137                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
138                                            device_info, device, strerror(errno));
139                                 return false;
140                         }
141
142                         packet->len = inlen + 10;
143                         break;
144                 case DEVICE_TYPE_TAP:
145                         inlen = read(device_fd, packet->data, MTU);
146
147                         if(inlen <= 0) {
148                                 logger(LOG_ERR, "Error while reading from %s %s: %s",
149                                            device_info, device, strerror(errno));
150                                 return false;
151                         }
152
153                         packet->len = inlen;
154                         break;
155                 default:
156                         abort();
157         }
158
159         device_in_packets++;
160         device_in_bytes += packet->len;
161
162         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
163                            device_info);
164
165         return true;
166 }
167
168 static bool write_packet(vpn_packet_t *packet) {
169         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Writing packet of %d bytes to %s",
170                            packet->len, device_info);
171
172         switch(device_type) {
173                 case DEVICE_TYPE_TUN:
174                         packet->data[10] = packet->data[11] = 0;
175                         if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
176                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
177                                            strerror(errno));
178                                 return false;
179                         }
180                         break;
181                 case DEVICE_TYPE_TAP:
182                         if(write(device_fd, packet->data, packet->len) < 0) {
183                                 logger(LOG_ERR, "Can't write to %s %s: %s", device_info, device,
184                                            strerror(errno));
185                                 return false;
186                         }
187                         break;
188                 default:
189                         abort();
190         }
191
192         device_out_packets++;
193         device_out_bytes += packet->len;
194
195         return true;
196 }
197
198 static void dump_device_stats(void) {
199         logger(LOG_DEBUG, "Statistics for %s %s:", device_info, device);
200         logger(LOG_DEBUG, " total bytes in:  %10"PRIu64, device_in_bytes);
201         logger(LOG_DEBUG, " total bytes out: %10"PRIu64, device_out_bytes);
202 }
203
204 const devops_t os_devops = {
205         .setup = setup_device,
206         .close = close_device,
207         .read = read_packet,
208         .write = write_packet,
209         .dump_stats = dump_device_stats,
210 };