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1 /*
2     net_socket.c -- Handle various kinds of sockets.
3     Copyright (C) 1998-2005 Ivo Timmermans,
4                   2000-2012 Guus Sliepen <guus@tinc-vpn.org>
5                   2006      Scott Lamb <slamb@slamb.org>
6                   2009      Florian Forster <octo@verplant.org>
7
8     This program is free software; you can redistribute it and/or modify
9     it under the terms of the GNU General Public License as published by
10     the Free Software Foundation; either version 2 of the License, or
11     (at your option) any later version.
12
13     This program is distributed in the hope that it will be useful,
14     but WITHOUT ANY WARRANTY; without even the implied warranty of
15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16     GNU General Public License for more details.
17
18     You should have received a copy of the GNU General Public License along
19     with this program; if not, write to the Free Software Foundation, Inc.,
20     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
21 */
22
23 #include "system.h"
24
25 #include "avl_tree.h"
26 #include "conf.h"
27 #include "connection.h"
28 #include "event.h"
29 #include "logger.h"
30 #include "meta.h"
31 #include "net.h"
32 #include "netutl.h"
33 #include "protocol.h"
34 #include "utils.h"
35 #include "xalloc.h"
36
37 /* Needed on Mac OS/X */
38 #ifndef SOL_TCP
39 #define SOL_TCP IPPROTO_TCP
40 #endif
41
42 int addressfamily = AF_UNSPEC;
43 int maxtimeout = 900;
44 int seconds_till_retry = 5;
45 int udp_rcvbuf = 0;
46 int udp_sndbuf = 0;
47
48 listen_socket_t listen_socket[MAXSOCKETS];
49 int listen_sockets;
50 list_t *outgoing_list = NULL;
51
52 /* Setup sockets */
53
54 static void configure_tcp(connection_t *c) {
55         int option;
56
57 #ifdef O_NONBLOCK
58         int flags = fcntl(c->socket, F_GETFL);
59
60         if(fcntl(c->socket, F_SETFL, flags | O_NONBLOCK) < 0) {
61                 logger(LOG_ERR, "fcntl for %s: %s", c->hostname, strerror(errno));
62         }
63 #elif defined(WIN32)
64         unsigned long arg = 1;
65
66         if(ioctlsocket(c->socket, FIONBIO, &arg) != 0) {
67                 logger(LOG_ERR, "ioctlsocket for %s: %d", c->hostname, sockstrerror(sockerrno));
68         }
69 #endif
70
71 #if defined(SOL_TCP) && defined(TCP_NODELAY)
72         option = 1;
73         setsockopt(c->socket, SOL_TCP, TCP_NODELAY, (void *)&option, sizeof(option));
74 #endif
75
76 #if defined(SOL_IP) && defined(IP_TOS) && defined(IPTOS_LOWDELAY)
77         option = IPTOS_LOWDELAY;
78         setsockopt(c->socket, SOL_IP, IP_TOS, (void *)&option, sizeof(option));
79 #endif
80 }
81
82 static bool bind_to_interface(int sd) {
83         char *iface;
84
85 #if defined(SOL_SOCKET) && defined(SO_BINDTODEVICE)
86         struct ifreq ifr;
87         int status;
88 #endif /* defined(SOL_SOCKET) && defined(SO_BINDTODEVICE) */
89
90         if(!get_config_string (lookup_config (config_tree, "BindToInterface"), &iface))
91                 return true;
92
93 #if defined(SOL_SOCKET) && defined(SO_BINDTODEVICE)
94         memset(&ifr, 0, sizeof(ifr));
95         strncpy(ifr.ifr_ifrn.ifrn_name, iface, IFNAMSIZ);
96         ifr.ifr_ifrn.ifrn_name[IFNAMSIZ - 1] = 0;
97
98         status = setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(ifr));
99         if(status) {
100                 logger(LOG_ERR, "Can't bind to interface %s: %s", iface,
101                                 strerror(errno));
102                 return false;
103         }
104 #else /* if !defined(SOL_SOCKET) || !defined(SO_BINDTODEVICE) */
105         logger(LOG_WARNING, "%s not supported on this platform", "BindToInterface");
106 #endif
107
108         return true;
109 }
110
111 int setup_listen_socket(const sockaddr_t *sa) {
112         int nfd;
113         char *addrstr;
114         int option;
115         char *iface;
116
117         nfd = socket(sa->sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
118
119         if(nfd < 0) {
120                 ifdebug(STATUS) logger(LOG_ERR, "Creating metasocket failed: %s", sockstrerror(sockerrno));
121                 return -1;
122         }
123
124 #ifdef FD_CLOEXEC
125         fcntl(nfd, F_SETFD, FD_CLOEXEC);
126 #endif
127
128         /* Optimize TCP settings */
129
130         option = 1;
131         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof(option));
132
133 #if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
134         if(sa->sa.sa_family == AF_INET6)
135                 setsockopt(nfd, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
136 #endif
137
138         if(get_config_string
139            (lookup_config(config_tree, "BindToInterface"), &iface)) {
140 #if defined(SOL_SOCKET) && defined(SO_BINDTODEVICE)
141                 struct ifreq ifr;
142
143                 memset(&ifr, 0, sizeof(ifr));
144                 strncpy(ifr.ifr_ifrn.ifrn_name, iface, IFNAMSIZ);
145
146                 if(setsockopt(nfd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(ifr))) {
147                         closesocket(nfd);
148                         logger(LOG_ERR, "Can't bind to interface %s: %s", iface,
149                                    strerror(sockerrno));
150                         return -1;
151                 }
152 #else
153                 logger(LOG_WARNING, "%s not supported on this platform", "BindToInterface");
154 #endif
155         }
156
157         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
158                 closesocket(nfd);
159                 addrstr = sockaddr2hostname(sa);
160                 logger(LOG_ERR, "Can't bind to %s/tcp: %s", addrstr, sockstrerror(sockerrno));
161                 free(addrstr);
162                 return -1;
163         }
164
165         if(listen(nfd, 3)) {
166                 closesocket(nfd);
167                 logger(LOG_ERR, "System call `%s' failed: %s", "listen", sockstrerror(sockerrno));
168                 return -1;
169         }
170
171         return nfd;
172 }
173
174 int setup_vpn_in_socket(const sockaddr_t *sa) {
175         int nfd;
176         char *addrstr;
177         int option;
178
179         nfd = socket(sa->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
180
181         if(nfd < 0) {
182                 logger(LOG_ERR, "Creating UDP socket failed: %s", sockstrerror(sockerrno));
183                 return -1;
184         }
185
186 #ifdef FD_CLOEXEC
187         fcntl(nfd, F_SETFD, FD_CLOEXEC);
188 #endif
189
190 #ifdef O_NONBLOCK
191         {
192                 int flags = fcntl(nfd, F_GETFL);
193
194                 if(fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0) {
195                         closesocket(nfd);
196                         logger(LOG_ERR, "System call `%s' failed: %s", "fcntl",
197                                    strerror(errno));
198                         return -1;
199                 }
200         }
201 #elif defined(WIN32)
202         {
203                 unsigned long arg = 1;
204                 if(ioctlsocket(nfd, FIONBIO, &arg) != 0) {
205                         closesocket(nfd);
206                         logger(LOG_ERR, "Call to `%s' failed: %s", "ioctlsocket", sockstrerror(sockerrno));
207                         return -1;
208                 }
209         }
210 #endif
211
212         option = 1;
213         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof(option));
214         setsockopt(nfd, SOL_SOCKET, SO_BROADCAST, (void *)&option, sizeof(option));
215
216         if(udp_rcvbuf && setsockopt(nfd, SOL_SOCKET, SO_RCVBUF, (void *)&udp_rcvbuf, sizeof(udp_rcvbuf)))
217                 logger(LOG_WARNING, "Can't set UDP SO_RCVBUF to %i: %s", udp_rcvbuf, strerror(errno));
218
219         if(udp_sndbuf && setsockopt(nfd, SOL_SOCKET, SO_SNDBUF, (void *)&udp_sndbuf, sizeof(udp_sndbuf)))
220                 logger(LOG_WARNING, "Can't set UDP SO_SNDBUF to %i: %s", udp_sndbuf, strerror(errno));
221
222 #if defined(IPPROTO_IPV6) && defined(IPV6_V6ONLY)
223         if(sa->sa.sa_family == AF_INET6)
224                 setsockopt(nfd, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
225 #endif
226
227 #if defined(IP_DONTFRAG) && !defined(IP_DONTFRAGMENT)
228 #define IP_DONTFRAGMENT IP_DONTFRAG
229 #endif
230
231 #if defined(SOL_IP) && defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DO)
232         if(myself->options & OPTION_PMTU_DISCOVERY) {
233                 option = IP_PMTUDISC_DO;
234                 setsockopt(nfd, SOL_IP, IP_MTU_DISCOVER, (void *)&option, sizeof(option));
235         }
236 #elif defined(IPPROTO_IP) && defined(IP_DONTFRAGMENT)
237         if(myself->options & OPTION_PMTU_DISCOVERY) {
238                 option = 1;
239                 setsockopt(nfd, IPPROTO_IP, IP_DONTFRAGMENT, (void *)&option, sizeof(option));
240         }
241 #else
242 #warning No way to disable IPv4 fragmentation
243 #endif
244
245 #if defined(SOL_IPV6) && defined(IPV6_MTU_DISCOVER) && defined(IPV6_PMTUDISC_DO)
246         if(myself->options & OPTION_PMTU_DISCOVERY) {
247                 option = IPV6_PMTUDISC_DO;
248                 setsockopt(nfd, SOL_IPV6, IPV6_MTU_DISCOVER, (void *)&option, sizeof(option));
249         }
250 #elif defined(IPPROTO_IPV6) && defined(IPV6_DONTFRAG)
251         if(myself->options & OPTION_PMTU_DISCOVERY) {
252                 option = 1;
253                 setsockopt(nfd, IPPROTO_IPV6, IPV6_DONTFRAG, (void *)&option, sizeof(option));
254         }
255 #else
256 #warning No way to disable IPv6 fragmentation
257 #endif
258
259         if (!bind_to_interface(nfd)) {
260                 closesocket(nfd);
261                 return -1;
262         }
263
264         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
265                 closesocket(nfd);
266                 addrstr = sockaddr2hostname(sa);
267                 logger(LOG_ERR, "Can't bind to %s/udp: %s", addrstr, sockstrerror(sockerrno));
268                 free(addrstr);
269                 return -1;
270         }
271
272         return nfd;
273 } /* int setup_vpn_in_socket */
274
275 void retry_outgoing(outgoing_t *outgoing) {
276         outgoing->timeout += 5;
277
278         if(outgoing->timeout > maxtimeout)
279                 outgoing->timeout = maxtimeout;
280
281         if(outgoing->event)
282                 event_del(outgoing->event);
283         outgoing->event = new_event();
284         outgoing->event->handler = (event_handler_t) setup_outgoing_connection;
285         outgoing->event->time = now + outgoing->timeout;
286         outgoing->event->data = outgoing;
287         event_add(outgoing->event);
288
289         ifdebug(CONNECTIONS) logger(LOG_NOTICE,
290                            "Trying to re-establish outgoing connection in %d seconds",
291                            outgoing->timeout);
292 }
293
294 void finish_connecting(connection_t *c) {
295         ifdebug(CONNECTIONS) logger(LOG_INFO, "Connected to %s (%s)", c->name, c->hostname);
296
297         configure_tcp(c);
298
299         c->last_ping_time = now;
300
301         send_id(c);
302 }
303
304 void do_outgoing_connection(connection_t *c) {
305         char *address, *port, *space;
306         int result;
307
308         if(!c->outgoing) {
309                 logger(LOG_ERR, "do_outgoing_connection() for %s called without c->outgoing", c->name);
310                 abort();
311         }
312
313 begin:
314         if(!c->outgoing->ai) {
315                 if(!c->outgoing->cfg) {
316                         ifdebug(CONNECTIONS) logger(LOG_ERR, "Could not set up a meta connection to %s",
317                                            c->name);
318                         c->status.remove = true;
319                         retry_outgoing(c->outgoing);
320                         c->outgoing = NULL;
321                         return;
322                 }
323
324                 get_config_string(c->outgoing->cfg, &address);
325
326                 space = strchr(address, ' ');
327                 if(space) {
328                         port = xstrdup(space + 1);
329                         *space = 0;
330                 } else {
331                         if(!get_config_string(lookup_config(c->config_tree, "Port"), &port))
332                                 port = xstrdup("655");
333                 }
334
335                 c->outgoing->ai = str2addrinfo(address, port, SOCK_STREAM);
336                 free(address);
337                 free(port);
338
339                 c->outgoing->aip = c->outgoing->ai;
340                 c->outgoing->cfg = lookup_config_next(c->config_tree, c->outgoing->cfg);
341         }
342
343         if(!c->outgoing->aip) {
344                 if(c->outgoing->ai)
345                         freeaddrinfo(c->outgoing->ai);
346                 c->outgoing->ai = NULL;
347                 goto begin;
348         }
349
350         memcpy(&c->address, c->outgoing->aip->ai_addr, c->outgoing->aip->ai_addrlen);
351         c->outgoing->aip = c->outgoing->aip->ai_next;
352
353         if(c->hostname)
354                 free(c->hostname);
355
356         c->hostname = sockaddr2hostname(&c->address);
357
358         ifdebug(CONNECTIONS) logger(LOG_INFO, "Trying to connect to %s (%s)", c->name,
359                            c->hostname);
360
361         c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
362
363 #ifdef FD_CLOEXEC
364         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
365 #endif
366
367         if(c->socket == -1) {
368                 ifdebug(CONNECTIONS) logger(LOG_ERR, "Creating socket for %s failed: %s", c->hostname, sockstrerror(sockerrno));
369                 goto begin;
370         }
371
372 #if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
373         int option = 1;
374         if(c->address.sa.sa_family == AF_INET6)
375                 setsockopt(c->socket, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
376 #endif
377
378         bind_to_interface(c->socket);
379
380         /* Optimize TCP settings */
381
382         configure_tcp(c);
383
384         /* Connect */
385
386         result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
387
388         if(result == -1) {
389                 if(sockinprogress(sockerrno)) {
390                         c->status.connecting = true;
391                         return;
392                 }
393
394                 closesocket(c->socket);
395
396                 ifdebug(CONNECTIONS) logger(LOG_ERR, "%s: %s", c->hostname, sockstrerror(sockerrno));
397
398                 goto begin;
399         }
400
401         finish_connecting(c);
402
403         return;
404 }
405
406 void setup_outgoing_connection(outgoing_t *outgoing) {
407         connection_t *c;
408         node_t *n;
409
410         outgoing->event = NULL;
411
412         n = lookup_node(outgoing->name);
413
414         if(n)
415                 if(n->connection) {
416                         ifdebug(CONNECTIONS) logger(LOG_INFO, "Already connected to %s", outgoing->name);
417
418                         n->connection->outgoing = outgoing;
419                         return;
420                 }
421
422         c = new_connection();
423         c->name = xstrdup(outgoing->name);
424         c->outcipher = myself->connection->outcipher;
425         c->outdigest = myself->connection->outdigest;
426         c->outmaclength = myself->connection->outmaclength;
427         c->outcompression = myself->connection->outcompression;
428
429         init_configuration(&c->config_tree);
430         read_connection_config(c);
431
432         outgoing->cfg = lookup_config(c->config_tree, "Address");
433
434         if(!outgoing->cfg) {
435                 logger(LOG_ERR, "No address specified for %s", c->name);
436                 free_connection(c);
437                 return;
438         }
439
440         c->outgoing = outgoing;
441         c->last_ping_time = now;
442
443         connection_add(c);
444
445         do_outgoing_connection(c);
446 }
447
448 /*
449   accept a new tcp connect and create a
450   new connection
451 */
452 bool handle_new_meta_connection(int sock) {
453         connection_t *c;
454         sockaddr_t sa;
455         int fd;
456         socklen_t len = sizeof(sa);
457
458         fd = accept(sock, &sa.sa, &len);
459
460         if(fd < 0) {
461                 logger(LOG_ERR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
462                 return false;
463         }
464
465         sockaddrunmap(&sa);
466
467         c = new_connection();
468         c->name = xstrdup("<unknown>");
469         c->outcipher = myself->connection->outcipher;
470         c->outdigest = myself->connection->outdigest;
471         c->outmaclength = myself->connection->outmaclength;
472         c->outcompression = myself->connection->outcompression;
473
474         c->address = sa;
475         c->hostname = sockaddr2hostname(&sa);
476         c->socket = fd;
477         c->last_ping_time = now;
478
479         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection from %s", c->hostname);
480
481         configure_tcp(c);
482
483         connection_add(c);
484
485         c->allow_request = ID;
486         send_id(c);
487
488         return true;
489 }
490
491 static void free_outgoing(outgoing_t *outgoing) {
492         if(outgoing->ai)
493                 freeaddrinfo(outgoing->ai);
494
495         if(outgoing->name)
496                 free(outgoing->name);
497
498         free(outgoing);
499 }
500
501 void try_outgoing_connections(void) {
502         static config_t *cfg = NULL;
503         char *name;
504         outgoing_t *outgoing;
505         
506         outgoing_list = list_alloc((list_action_t)free_outgoing);
507                         
508         for(cfg = lookup_config(config_tree, "ConnectTo"); cfg; cfg = lookup_config_next(config_tree, cfg)) {
509                 get_config_string(cfg, &name);
510
511                 if(!check_id(name)) {
512                         logger(LOG_ERR,
513                                    "Invalid name for outgoing connection in %s line %d",
514                                    cfg->file, cfg->line);
515                         free(name);
516                         continue;
517                 }
518
519                 outgoing = xmalloc_and_zero(sizeof(*outgoing));
520                 outgoing->name = name;
521                 list_insert_tail(outgoing_list, outgoing);
522                 setup_outgoing_connection(outgoing);
523         }
524 }