Fix PMTU discovery via datagram SPTPS.
[tinc] / src / net.c
1 /*
2     net.c -- most of the network code
3     Copyright (C) 1998-2005 Ivo Timmermans,
4                   2000-2013 Guus Sliepen <guus@tinc-vpn.org>
5                   2006      Scott Lamb <slamb@slamb.org>
6                   2011      Loïc Grenié <loic.grenie@gmail.com>
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 "utils.h"
26 #include "conf.h"
27 #include "connection.h"
28 #include "device.h"
29 #include "graph.h"
30 #include "logger.h"
31 #include "meta.h"
32 #include "names.h"
33 #include "net.h"
34 #include "netutl.h"
35 #include "protocol.h"
36 #include "subnet.h"
37 #include "xalloc.h"
38
39 int contradicting_add_edge = 0;
40 int contradicting_del_edge = 0;
41 static int sleeptime = 10;
42 time_t last_config_check = 0;
43 static timeout_t pingtimer;
44 static timeout_t periodictimer;
45
46 /* Purge edges and subnets of unreachable nodes. Use carefully. */
47
48 void purge(void) {
49         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Purging unreachable nodes");
50
51         /* Remove all edges and subnets owned by unreachable nodes. */
52
53         for splay_each(node_t, n, node_tree) {
54                 if(!n->status.reachable) {
55                         logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Purging node %s (%s)", n->name, n->hostname);
56
57                         for splay_each(subnet_t, s, n->subnet_tree) {
58                                 send_del_subnet(everyone, s);
59                                 if(!strictsubnets)
60                                         subnet_del(n, s);
61                         }
62
63                         for splay_each(edge_t, e, n->edge_tree) {
64                                 if(!tunnelserver)
65                                         send_del_edge(everyone, e);
66                                 edge_del(e);
67                         }
68                 }
69         }
70
71         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
72
73         for splay_each(node_t, n, node_tree) {
74                 if(!n->status.reachable) {
75                         for splay_each(edge_t, e, edge_weight_tree)
76                                 if(e->to == n)
77                                         return;
78
79                         if(!autoconnect && (!strictsubnets || !n->subnet_tree->head))
80                                 /* in strictsubnets mode do not delete nodes with subnets */
81                                 node_del(n);
82                 }
83         }
84 }
85
86 /*
87   Terminate a connection:
88   - Mark it as inactive
89   - Remove the edge representing this connection
90   - Kill it with fire
91   - Check if we need to retry making an outgoing connection
92 */
93 void terminate_connection(connection_t *c, bool report) {
94         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Closing connection with %s (%s)", c->name, c->hostname);
95
96         c->status.active = false;
97
98         if(c->node && c->node->connection == c)
99                 c->node->connection = NULL;
100
101         if(c->edge) {
102                 if(report && !tunnelserver)
103                         send_del_edge(everyone, c->edge);
104
105                 edge_del(c->edge);
106                 c->edge = NULL;
107
108                 /* Run MST and SSSP algorithms */
109
110                 graph();
111
112                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
113
114                 if(report && !c->node->status.reachable) {
115                         edge_t *e;
116                         e = lookup_edge(c->node, myself);
117                         if(e) {
118                                 if(!tunnelserver)
119                                         send_del_edge(everyone, e);
120                                 edge_del(e);
121                         }
122                 }
123         }
124
125         outgoing_t *outgoing = c->outgoing;
126         connection_del(c);
127
128         /* Check if this was our outgoing connection */
129
130         if(outgoing)
131                 do_outgoing_connection(outgoing);
132
133 #ifndef HAVE_MINGW
134         /* Clean up dead proxy processes */
135
136         while(waitpid(-1, NULL, WNOHANG) > 0);
137 #endif
138 }
139
140 /*
141   Check if the other end is active.
142   If we have sent packets, but didn't receive any,
143   then possibly the other end is dead. We send a
144   PING request over the meta connection. If the other
145   end does not reply in time, we consider them dead
146   and close the connection.
147 */
148 static void timeout_handler(void *data) {
149         for list_each(connection_t, c, connection_list) {
150                 if(c->status.control)
151                         continue;
152
153                 if(c->last_ping_time + pingtimeout <= now.tv_sec) {
154                         if(c->status.active) {
155                                 if(c->status.pinged) {
156                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds", c->name, c->hostname, (long)now.tv_sec - c->last_ping_time);
157                                 } else if(c->last_ping_time + pinginterval <= now.tv_sec) {
158                                         send_ping(c);
159                                         continue;
160                                 } else {
161                                         continue;
162                                 }
163                         } else {
164                                 if(c->status.connecting)
165                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout while connecting to %s (%s)", c->name, c->hostname);
166                                 else
167                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout from %s (%s) during authentication", c->name, c->hostname);
168                         }
169                         terminate_connection(c, c->status.active);
170                 }
171         }
172
173         timeout_set(data, &(struct timeval){pingtimeout, rand() % 100000});
174 }
175
176 static void periodic_handler(void *data) {
177         /* Check if there are too many contradicting ADD_EDGE and DEL_EDGE messages.
178            This usually only happens when another node has the same Name as this node.
179            If so, sleep for a short while to prevent a storm of contradicting messages.
180         */
181
182         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
183                 logger(DEBUG_ALWAYS, LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
184                 usleep(sleeptime * 1000000LL);
185                 sleeptime *= 2;
186                 if(sleeptime < 0)
187                         sleeptime = 3600;
188         } else {
189                 sleeptime /= 2;
190                 if(sleeptime < 10)
191                         sleeptime = 10;
192         }
193
194         contradicting_add_edge = 0;
195         contradicting_del_edge = 0;
196
197         /* If AutoConnect is set, check if we need to make or break connections. */
198
199         if(autoconnect && node_tree->count > 1) {
200                 /* Count number of active connections */
201                 int nc = 0;
202                 for list_each(connection_t, c, connection_list) {
203                         if(c->status.active && !c->status.control)
204                                 nc++;
205                 }
206
207                 if(nc < 3) {
208                         /* Not enough active connections, try to add one.
209                            Choose a random node, if we don't have a connection to it,
210                            and we are not already trying to make one, create an
211                            outgoing connection to this node.
212                         */
213                         int r = rand() % node_tree->count;
214                         int i = 0;
215
216                         for splay_each(node_t, n, node_tree) {
217                                 if(i++ != r)
218                                         continue;
219
220                                 if(n->connection)
221                                         break;
222
223                                 bool found = false;
224
225                                 for list_each(outgoing_t, outgoing, outgoing_list) {
226                                         if(!strcmp(outgoing->name, n->name)) {
227                                                 found = true;
228                                                 break;
229                                         }
230                                 }
231
232                                 if(!found) {
233                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Autoconnecting to %s", n->name);
234                                         outgoing_t *outgoing = xzalloc(sizeof *outgoing);
235                                         outgoing->name = xstrdup(n->name);
236                                         list_insert_tail(outgoing_list, outgoing);
237                                         setup_outgoing_connection(outgoing);
238                                 }
239                                 break;
240                         }
241                 } else if(nc > 3) {
242                         /* Too many active connections, try to remove one.
243                            Choose a random outgoing connection to a node
244                            that has at least one other connection.
245                         */
246                         int r = rand() % nc;
247                         int i = 0;
248
249                         for list_each(connection_t, c, connection_list) {
250                                 if(!c->status.active || c->status.control)
251                                         continue;
252
253                                 if(i++ != r)
254                                         continue;
255
256                                 if(!c->outgoing || !c->node || c->node->edge_tree->count < 2)
257                                         break;
258
259                                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Autodisconnecting from %s", c->name);
260                                 list_delete(outgoing_list, c->outgoing);
261                                 c->outgoing = NULL;
262                                 terminate_connection(c, c->status.active);
263                                 break;
264                         }
265                 }
266
267                 if(nc >= 3) {
268                         /* If we have enough active connections,
269                            remove any pending outgoing connections.
270                         */
271                         for list_each(outgoing_t, o, outgoing_list) {
272                                 bool found = false;
273                                 for list_each(connection_t, c, connection_list) {
274                                         if(c->outgoing == o) {
275                                                 found = true;
276                                                 break;
277                                         }
278                                 }
279                                 if(!found) {
280                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Cancelled outgoing connection to %s", o->name);
281                                         list_delete_node(outgoing_list, node);
282                                 }
283                         }
284                 }
285         }
286
287         timeout_set(data, &(struct timeval){5, rand() % 100000});
288 }
289
290 void handle_meta_connection_data(connection_t *c) {
291         if (!receive_meta(c)) {
292                 terminate_connection(c, c->status.active);
293                 return;
294         }
295 }
296
297 #ifndef HAVE_MINGW
298 static void sigterm_handler(void *data) {
299         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
300         event_exit();
301 }
302
303 static void sighup_handler(void *data) {
304         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
305         reopenlogger();
306         if(reload_configuration())
307                 exit(1);
308 }
309
310 static void sigalrm_handler(void *data) {
311         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
312         retry();
313 }
314 #endif
315
316 int reload_configuration(void) {
317         char *fname = NULL;
318
319         /* Reread our own configuration file */
320
321         exit_configuration(&config_tree);
322         init_configuration(&config_tree);
323
324         if(!read_server_config()) {
325                 logger(DEBUG_ALWAYS, LOG_ERR, "Unable to reread configuration file.");
326                 return EINVAL;
327         }
328
329         read_config_options(config_tree, NULL);
330
331         xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, myself->name);
332         read_config_file(config_tree, fname);
333         free(fname);
334
335         /* Parse some options that are allowed to be changed while tinc is running */
336
337         setup_myself_reloadable();
338
339         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
340
341         if(strictsubnets) {
342                 for splay_each(subnet_t, subnet, subnet_tree)
343                         subnet->expires = 1;
344
345                 load_all_subnets();
346
347                 for splay_each(subnet_t, subnet, subnet_tree) {
348                         if(subnet->expires == 1) {
349                                 send_del_subnet(everyone, subnet);
350                                 if(subnet->owner->status.reachable)
351                                         subnet_update(subnet->owner, subnet, false);
352                                 subnet_del(subnet->owner, subnet);
353                         } else if(subnet->expires == -1) {
354                                 subnet->expires = 0;
355                         } else {
356                                 send_add_subnet(everyone, subnet);
357                                 if(subnet->owner->status.reachable)
358                                         subnet_update(subnet->owner, subnet, true);
359                         }
360                 }
361         } else { /* Only read our own subnets back in */
362                 for splay_each(subnet_t, subnet, myself->subnet_tree)
363                         if(!subnet->expires)
364                                 subnet->expires = 1;
365
366                 config_t *cfg = lookup_config(config_tree, "Subnet");
367
368                 while(cfg) {
369                         subnet_t *subnet, *s2;
370
371                         if(!get_config_subnet(cfg, &subnet))
372                                 continue;
373
374                         if((s2 = lookup_subnet(myself, subnet))) {
375                                 if(s2->expires == 1)
376                                         s2->expires = 0;
377
378                                 free_subnet(subnet);
379                         } else {
380                                 subnet_add(myself, subnet);
381                                 send_add_subnet(everyone, subnet);
382                                 subnet_update(myself, subnet, true);
383                         }
384
385                         cfg = lookup_config_next(config_tree, cfg);
386                 }
387
388                 for splay_each(subnet_t, subnet, myself->subnet_tree) {
389                         if(subnet->expires == 1) {
390                                 send_del_subnet(everyone, subnet);
391                                 subnet_update(myself, subnet, false);
392                                 subnet_del(myself, subnet);
393                         }
394                 }
395         }
396
397         /* Try to make outgoing connections */
398
399         try_outgoing_connections();
400
401         /* Close connections to hosts that have a changed or deleted host config file */
402
403         for list_each(connection_t, c, connection_list) {
404                 if(c->status.control)
405                         continue;
406
407                 xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, c->name);
408                 struct stat s;
409                 if(stat(fname, &s) || s.st_mtime > last_config_check) {
410                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Host config file of %s has been changed", c->name);
411                         terminate_connection(c, c->status.active);
412                 }
413                 free(fname);
414         }
415
416         last_config_check = now.tv_sec;
417
418         return 0;
419 }
420
421 void retry(void) {
422         /* Reset the reconnection timers for all outgoing connections */
423         for list_each(outgoing_t, outgoing, outgoing_list) {
424                 outgoing->timeout = 0;
425                 if(outgoing->ev.cb)
426                         timeout_set(&outgoing->ev, &(struct timeval){0, 0});
427         }
428
429         /* Check for outgoing connections that are in progress, and reset their ping timers */
430         for list_each(connection_t, c, connection_list) {
431                 if(c->outgoing && !c->node)
432                         c->last_ping_time = 0;
433         }
434
435         /* Kick the ping timeout handler */
436         timeout_set(&pingtimer, &(struct timeval){0, 0});
437 }
438
439 /*
440   this is where it all happens...
441 */
442 int main_loop(void) {
443         timeout_add(&pingtimer, timeout_handler, &pingtimer, &(struct timeval){pingtimeout, rand() % 100000});
444         timeout_add(&periodictimer, periodic_handler, &periodictimer, &(struct timeval){pingtimeout, rand() % 100000});
445
446 #ifndef HAVE_MINGW
447         signal_t sighup = {0};
448         signal_t sigterm = {0};
449         signal_t sigquit = {0};
450         signal_t sigint = {0};
451         signal_t sigalrm = {0};
452
453         signal_add(&sighup, sighup_handler, &sighup, SIGHUP);
454         signal_add(&sigterm, sigterm_handler, &sigterm, SIGTERM);
455         signal_add(&sigquit, sigterm_handler, &sigquit, SIGQUIT);
456         signal_add(&sigint, sigterm_handler, &sigint, SIGINT);
457         signal_add(&sigalrm, sigalrm_handler, &sigalrm, SIGALRM);
458 #endif
459
460         if(!event_loop()) {
461                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while waiting for input: %s", strerror(errno));
462                 return 1;
463         }
464
465 #ifndef HAVE_MINGW
466         signal_del(&sighup);
467         signal_del(&sigterm);
468         signal_del(&sigquit);
469         signal_del(&sigint);
470         signal_del(&sigalrm);
471 #endif
472
473         timeout_del(&periodictimer);
474         timeout_del(&pingtimer);
475
476         return 0;
477 }