Send one MTU probe at a time.
[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 #ifdef HAVE_RESOLV_H
40 #include <resolv.h>
41 #endif
42
43 int contradicting_add_edge = 0;
44 int contradicting_del_edge = 0;
45 static int sleeptime = 10;
46 time_t last_config_check = 0;
47 static timeout_t pingtimer;
48 static timeout_t periodictimer;
49
50 /* Purge edges and subnets of unreachable nodes. Use carefully. */
51
52 void purge(void) {
53         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Purging unreachable nodes");
54
55         /* Remove all edges and subnets owned by unreachable nodes. */
56
57         for splay_each(node_t, n, node_tree) {
58                 if(!n->status.reachable) {
59                         logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Purging node %s (%s)", n->name, n->hostname);
60
61                         for splay_each(subnet_t, s, n->subnet_tree) {
62                                 send_del_subnet(everyone, s);
63                                 if(!strictsubnets)
64                                         subnet_del(n, s);
65                         }
66
67                         for splay_each(edge_t, e, n->edge_tree) {
68                                 if(!tunnelserver)
69                                         send_del_edge(everyone, e);
70                                 edge_del(e);
71                         }
72                 }
73         }
74
75         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
76
77         for splay_each(node_t, n, node_tree) {
78                 if(!n->status.reachable) {
79                         for splay_each(edge_t, e, edge_weight_tree)
80                                 if(e->to == n)
81                                         return;
82
83                         if(!autoconnect && (!strictsubnets || !n->subnet_tree->head))
84                                 /* in strictsubnets mode do not delete nodes with subnets */
85                                 node_del(n);
86                 }
87         }
88 }
89
90 /*
91   Terminate a connection:
92   - Mark it as inactive
93   - Remove the edge representing this connection
94   - Kill it with fire
95   - Check if we need to retry making an outgoing connection
96 */
97 void terminate_connection(connection_t *c, bool report) {
98         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Closing connection with %s (%s)", c->name, c->hostname);
99
100         if(c->node && c->node->connection == c)
101                 c->node->connection = NULL;
102
103         if(c->edge) {
104                 if(report && !tunnelserver)
105                         send_del_edge(everyone, c->edge);
106
107                 edge_del(c->edge);
108                 c->edge = NULL;
109
110                 /* Run MST and SSSP algorithms */
111
112                 graph();
113
114                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
115
116                 if(report && !c->node->status.reachable) {
117                         edge_t *e;
118                         e = lookup_edge(c->node, myself);
119                         if(e) {
120                                 if(!tunnelserver)
121                                         send_del_edge(everyone, e);
122                                 edge_del(e);
123                         }
124                 }
125         }
126
127         outgoing_t *outgoing = c->outgoing;
128         connection_del(c);
129
130         /* Check if this was our outgoing connection */
131
132         if(outgoing)
133                 do_outgoing_connection(outgoing);
134
135 #ifndef HAVE_MINGW
136         /* Clean up dead proxy processes */
137
138         while(waitpid(-1, NULL, WNOHANG) > 0);
139 #endif
140 }
141
142 /*
143   Check if the other end is active.
144   If we have sent packets, but didn't receive any,
145   then possibly the other end is dead. We send a
146   PING request over the meta connection. If the other
147   end does not reply in time, we consider them dead
148   and close the connection.
149 */
150 static void timeout_handler(void *data) {
151         for list_each(connection_t, c, connection_list) {
152                 if(c->status.control)
153                         continue;
154
155                 if(c->last_ping_time + pingtimeout <= now.tv_sec) {
156                         if(c->edge) {
157                                 if(c->status.pinged) {
158                                         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);
159                                 } else if(c->last_ping_time + pinginterval <= now.tv_sec) {
160                                         send_ping(c);
161                                         continue;
162                                 } else {
163                                         continue;
164                                 }
165                         } else {
166                                 if(c->status.connecting)
167                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout while connecting to %s (%s)", c->name, c->hostname);
168                                 else
169                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout from %s (%s) during authentication", c->name, c->hostname);
170                         }
171                         terminate_connection(c, c->edge);
172                 }
173         }
174
175         timeout_set(data, &(struct timeval){pingtimeout, rand() % 100000});
176 }
177
178 static void periodic_handler(void *data) {
179         /* Check if there are too many contradicting ADD_EDGE and DEL_EDGE messages.
180            This usually only happens when another node has the same Name as this node.
181            If so, sleep for a short while to prevent a storm of contradicting messages.
182         */
183
184         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
185                 logger(DEBUG_ALWAYS, LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
186                 usleep(sleeptime * 1000000LL);
187                 sleeptime *= 2;
188                 if(sleeptime < 0)
189                         sleeptime = 3600;
190         } else {
191                 sleeptime /= 2;
192                 if(sleeptime < 10)
193                         sleeptime = 10;
194         }
195
196         contradicting_add_edge = 0;
197         contradicting_del_edge = 0;
198
199         /* If AutoConnect is set, check if we need to make or break connections. */
200
201         if(autoconnect && node_tree->count > 1) {
202                 /* Count number of active connections */
203                 int nc = 0;
204                 for list_each(connection_t, c, connection_list) {
205                         if(c->edge)
206                                 nc++;
207                 }
208
209                 if(nc < 3) {
210                         /* Not enough active connections, try to add one.
211                            Choose a random node, if we don't have a connection to it,
212                            and we are not already trying to make one, create an
213                            outgoing connection to this node.
214                         */
215                         int r = rand() % node_tree->count;
216                         int i = 0;
217
218                         for splay_each(node_t, n, node_tree) {
219                                 if(i++ != r)
220                                         continue;
221
222                                 if(n->connection)
223                                         break;
224
225                                 bool found = false;
226
227                                 for list_each(outgoing_t, outgoing, outgoing_list) {
228                                         if(!strcmp(outgoing->name, n->name)) {
229                                                 found = true;
230                                                 break;
231                                         }
232                                 }
233
234                                 if(!found) {
235                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Autoconnecting to %s", n->name);
236                                         outgoing_t *outgoing = xzalloc(sizeof *outgoing);
237                                         outgoing->name = xstrdup(n->name);
238                                         list_insert_tail(outgoing_list, outgoing);
239                                         setup_outgoing_connection(outgoing);
240                                 }
241                                 break;
242                         }
243                 } else if(nc > 3) {
244                         /* Too many active connections, try to remove one.
245                            Choose a random outgoing connection to a node
246                            that has at least one other connection.
247                         */
248                         int r = rand() % nc;
249                         int i = 0;
250
251                         for list_each(connection_t, c, connection_list) {
252                                 if(!c->edge)
253                                         continue;
254
255                                 if(i++ != r)
256                                         continue;
257
258                                 if(!c->outgoing || !c->node || c->node->edge_tree->count < 2)
259                                         break;
260
261                                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Autodisconnecting from %s", c->name);
262                                 list_delete(outgoing_list, c->outgoing);
263                                 c->outgoing = NULL;
264                                 terminate_connection(c, c->edge);
265                                 break;
266                         }
267                 }
268
269                 if(nc >= 3) {
270                         /* If we have enough active connections,
271                            remove any pending outgoing connections.
272                         */
273                         for list_each(outgoing_t, o, outgoing_list) {
274                                 bool found = false;
275                                 for list_each(connection_t, c, connection_list) {
276                                         if(c->outgoing == o) {
277                                                 found = true;
278                                                 break;
279                                         }
280                                 }
281                                 if(!found) {
282                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Cancelled outgoing connection to %s", o->name);
283                                         list_delete_node(outgoing_list, node);
284                                 }
285                         }
286                 }
287         }
288
289         timeout_set(data, &(struct timeval){5, rand() % 100000});
290 }
291
292 void handle_meta_connection_data(connection_t *c) {
293         if (!receive_meta(c)) {
294                 terminate_connection(c, c->edge);
295                 return;
296         }
297 }
298
299 #ifndef HAVE_MINGW
300 static void sigterm_handler(void *data) {
301         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
302         event_exit();
303 }
304
305 static void sighup_handler(void *data) {
306         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
307         reopenlogger();
308         if(reload_configuration())
309                 exit(1);
310 }
311
312 static void sigalrm_handler(void *data) {
313         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
314 #ifdef HAVE_DECL_RES_INIT
315         res_init();
316 #endif
317         retry();
318 }
319 #endif
320
321 int reload_configuration(void) {
322         char *fname = NULL;
323
324         /* Reread our own configuration file */
325
326         exit_configuration(&config_tree);
327         init_configuration(&config_tree);
328
329         if(!read_server_config()) {
330                 logger(DEBUG_ALWAYS, LOG_ERR, "Unable to reread configuration file.");
331                 return EINVAL;
332         }
333
334         read_config_options(config_tree, NULL);
335
336         xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, myself->name);
337         read_config_file(config_tree, fname);
338         free(fname);
339
340         /* Parse some options that are allowed to be changed while tinc is running */
341
342         setup_myself_reloadable();
343
344         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
345
346         if(strictsubnets) {
347                 for splay_each(subnet_t, subnet, subnet_tree)
348                         if (subnet->owner)
349                                 subnet->expires = 1;
350
351                 load_all_subnets();
352
353                 for splay_each(subnet_t, subnet, subnet_tree) {
354                         if (!subnet->owner)
355                                 continue;
356                         if(subnet->expires == 1) {
357                                 send_del_subnet(everyone, subnet);
358                                 if(subnet->owner->status.reachable)
359                                         subnet_update(subnet->owner, subnet, false);
360                                 subnet_del(subnet->owner, subnet);
361                         } else if(subnet->expires == -1) {
362                                 subnet->expires = 0;
363                         } else {
364                                 send_add_subnet(everyone, subnet);
365                                 if(subnet->owner->status.reachable)
366                                         subnet_update(subnet->owner, subnet, true);
367                         }
368                 }
369         } else { /* Only read our own subnets back in */
370                 for splay_each(subnet_t, subnet, myself->subnet_tree)
371                         if(!subnet->expires)
372                                 subnet->expires = 1;
373
374                 config_t *cfg = lookup_config(config_tree, "Subnet");
375
376                 while(cfg) {
377                         subnet_t *subnet, *s2;
378
379                         if(!get_config_subnet(cfg, &subnet))
380                                 continue;
381
382                         if((s2 = lookup_subnet(myself, subnet))) {
383                                 if(s2->expires == 1)
384                                         s2->expires = 0;
385
386                                 free_subnet(subnet);
387                         } else {
388                                 subnet_add(myself, subnet);
389                                 send_add_subnet(everyone, subnet);
390                                 subnet_update(myself, subnet, true);
391                         }
392
393                         cfg = lookup_config_next(config_tree, cfg);
394                 }
395
396                 for splay_each(subnet_t, subnet, myself->subnet_tree) {
397                         if(subnet->expires == 1) {
398                                 send_del_subnet(everyone, subnet);
399                                 subnet_update(myself, subnet, false);
400                                 subnet_del(myself, subnet);
401                         }
402                 }
403         }
404
405         /* Try to make outgoing connections */
406
407         try_outgoing_connections();
408
409         /* Close connections to hosts that have a changed or deleted host config file */
410
411         for list_each(connection_t, c, connection_list) {
412                 if(c->status.control)
413                         continue;
414
415                 xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, c->name);
416                 struct stat s;
417                 if(stat(fname, &s) || s.st_mtime > last_config_check) {
418                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Host config file of %s has been changed", c->name);
419                         terminate_connection(c, c->edge);
420                 }
421                 free(fname);
422         }
423
424         last_config_check = now.tv_sec;
425
426         return 0;
427 }
428
429 void retry(void) {
430         /* Reset the reconnection timers for all outgoing connections */
431         for list_each(outgoing_t, outgoing, outgoing_list) {
432                 outgoing->timeout = 0;
433                 if(outgoing->ev.cb)
434                         timeout_set(&outgoing->ev, &(struct timeval){0, 0});
435         }
436
437         /* Check for outgoing connections that are in progress, and reset their ping timers */
438         for list_each(connection_t, c, connection_list) {
439                 if(c->outgoing && !c->node)
440                         c->last_ping_time = 0;
441         }
442
443         /* Kick the ping timeout handler */
444         timeout_set(&pingtimer, &(struct timeval){0, 0});
445 }
446
447 /*
448   this is where it all happens...
449 */
450 int main_loop(void) {
451         timeout_add(&pingtimer, timeout_handler, &pingtimer, &(struct timeval){pingtimeout, rand() % 100000});
452         timeout_add(&periodictimer, periodic_handler, &periodictimer, &(struct timeval){pingtimeout, rand() % 100000});
453
454 #ifndef HAVE_MINGW
455         signal_t sighup = {0};
456         signal_t sigterm = {0};
457         signal_t sigquit = {0};
458         signal_t sigint = {0};
459         signal_t sigalrm = {0};
460
461         signal_add(&sighup, sighup_handler, &sighup, SIGHUP);
462         signal_add(&sigterm, sigterm_handler, &sigterm, SIGTERM);
463         signal_add(&sigquit, sigterm_handler, &sigquit, SIGQUIT);
464         signal_add(&sigint, sigterm_handler, &sigint, SIGINT);
465         signal_add(&sigalrm, sigalrm_handler, &sigalrm, SIGALRM);
466 #endif
467
468         if(!event_loop()) {
469                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
470                 return 1;
471         }
472
473 #ifndef HAVE_MINGW
474         signal_del(&sighup);
475         signal_del(&sigterm);
476         signal_del(&sigquit);
477         signal_del(&sigint);
478         signal_del(&sigalrm);
479 #endif
480
481         timeout_del(&periodictimer);
482         timeout_del(&pingtimer);
483
484         return 0;
485 }