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1 /*
2     device.c -- Interaction with Linux ethertap and tun/tap device
3     Copyright (C) 2001-2005 Ivo Timmermans,
4                   2001-2013 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 uint64_t device_in_packets = 0;
50 uint64_t device_in_bytes = 0;
51 uint64_t device_out_packets = 0;
52 uint64_t device_out_bytes = 0;
53
54 static bool setup_device(void) {
55         if(!get_config_string(lookup_config(config_tree, "Device"), &device))
56                 device = xstrdup(DEFAULT_DEVICE);
57
58         if(!get_config_string(lookup_config(config_tree, "Interface"), &iface))
59                 if(netname)
60                         iface = xstrdup(netname);
61
62         device_fd = open(device, O_RDWR | O_NONBLOCK);
63
64         if(device_fd < 0) {
65                 logger(DEBUG_ALWAYS, LOG_ERR, "Could not open %s: %s", device, strerror(errno));
66                 return false;
67         }
68
69 #ifdef FD_CLOEXEC
70         fcntl(device_fd, F_SETFD, FD_CLOEXEC);
71 #endif
72
73         struct ifreq ifr = {{{0}}};
74
75         get_config_string(lookup_config(config_tree, "DeviceType"), &type);
76
77         if(type && strcasecmp(type, "tun") && strcasecmp(type, "tap")) {
78                 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown device type %s!", type);
79                 return false;
80         }
81
82         if((type && !strcasecmp(type, "tun")) || (!type && routing_mode == RMODE_ROUTER)) {
83                 ifr.ifr_flags = IFF_TUN;
84                 device_type = DEVICE_TYPE_TUN;
85                 device_info = "Linux tun/tap device (tun mode)";
86         } else {
87                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
88                 device_type = DEVICE_TYPE_TAP;
89                 device_info = "Linux tun/tap device (tap mode)";
90         }
91
92 #ifdef IFF_ONE_QUEUE
93         /* Set IFF_ONE_QUEUE flag... */
94
95         bool t1q = false;
96         if(get_config_bool(lookup_config(config_tree, "IffOneQueue"), &t1q) && t1q)
97                 ifr.ifr_flags |= IFF_ONE_QUEUE;
98 #endif
99
100         if(iface)
101                 strncpy(ifr.ifr_name, iface, IFNAMSIZ);
102
103         if(!ioctl(device_fd, TUNSETIFF, &ifr)) {
104                 strncpy(ifrname, ifr.ifr_name, IFNAMSIZ);
105                 free(iface);
106                 iface = xstrdup(ifrname);
107         }
108
109         logger(DEBUG_ALWAYS, LOG_INFO, "%s is a %s", device, device_info);
110
111         return true;
112 }
113
114 static void close_device(void) {
115         close(device_fd);
116
117         free(type);
118         free(device);
119         free(iface);
120 }
121
122 static bool read_packet(vpn_packet_t *packet) {
123         int inlen;
124
125         switch(device_type) {
126                 case DEVICE_TYPE_TUN:
127                         inlen = read(device_fd, packet->data + 10, MTU - 10);
128
129                         if(inlen <= 0) {
130                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while reading from %s %s: %s",
131                                            device_info, device, strerror(errno));
132                                 return false;
133                         }
134
135                         memset(packet->data, 0, 12);
136                         packet->len = inlen + 10;
137                         break;
138                 case DEVICE_TYPE_TAP:
139                         inlen = read(device_fd, packet->data, MTU);
140
141                         if(inlen <= 0) {
142                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while reading from %s %s: %s",
143                                            device_info, device, strerror(errno));
144                                 return false;
145                         }
146
147                         packet->len = inlen;
148                         break;
149                 default:
150                         abort();
151         }
152
153         device_in_packets++;
154         device_in_bytes += packet->len;
155
156         logger(DEBUG_TRAFFIC, LOG_DEBUG, "Read packet of %d bytes from %s", packet->len,
157                            device_info);
158
159         return true;
160 }
161
162 static bool write_packet(vpn_packet_t *packet) {
163         logger(DEBUG_TRAFFIC, LOG_DEBUG, "Writing packet of %d bytes to %s",
164                            packet->len, device_info);
165
166         switch(device_type) {
167                 case DEVICE_TYPE_TUN:
168                         packet->data[10] = packet->data[11] = 0;
169                         if(write(device_fd, packet->data + 10, packet->len - 10) < 0) {
170                                 logger(DEBUG_ALWAYS, LOG_ERR, "Can't write to %s %s: %s", device_info, device,
171                                            strerror(errno));
172                                 return false;
173                         }
174                         break;
175                 case DEVICE_TYPE_TAP:
176                         if(write(device_fd, packet->data, packet->len) < 0) {
177                                 logger(DEBUG_ALWAYS, LOG_ERR, "Can't write to %s %s: %s", device_info, device,
178                                            strerror(errno));
179                                 return false;
180                         }
181                         break;
182                 default:
183                         abort();
184         }
185
186         device_out_packets++;
187         device_out_bytes += packet->len;
188
189         return true;
190 }
191
192 static void dump_device_stats(void) {
193         logger(DEBUG_ALWAYS, LOG_DEBUG, "Statistics for %s %s:", device_info, device);
194         logger(DEBUG_ALWAYS, LOG_DEBUG, " total bytes in:  %10"PRIu64, device_in_bytes);
195         logger(DEBUG_ALWAYS, LOG_DEBUG, " total bytes out: %10"PRIu64, device_out_bytes);
196 }
197
198 const devops_t os_devops = {
199         .setup = setup_device,
200         .close = close_device,
201         .read = read_packet,
202         .write = write_packet,
203         .dump_stats = dump_device_stats,
204 };