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1 /*
2     net.c -- most of the network code
3     Copyright (C) 1998-2005 Ivo Timmermans,
4                   2000-2011 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 "splay_tree.h"
27 #include "conf.h"
28 #include "connection.h"
29 #include "device.h"
30 #include "graph.h"
31 #include "logger.h"
32 #include "meta.h"
33 #include "net.h"
34 #include "netutl.h"
35 #include "process.h"
36 #include "protocol.h"
37 #include "subnet.h"
38 #include "xalloc.h"
39
40 int contradicting_add_edge = 0;
41 int contradicting_del_edge = 0;
42 static int sleeptime = 10;
43
44 /* Purge edges and subnets of unreachable nodes. Use carefully. */
45
46 void purge(void) {
47         splay_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
48         node_t *n;
49         edge_t *e;
50         subnet_t *s;
51
52         ifdebug(PROTOCOL) logger(LOG_DEBUG, "Purging unreachable nodes");
53
54         /* Remove all edges and subnets owned by unreachable nodes. */
55
56         for(nnode = node_tree->head; nnode; nnode = nnext) {
57                 nnext = nnode->next;
58                 n = nnode->data;
59
60                 if(!n->status.reachable) {
61                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Purging node %s (%s)", n->name,
62                                            n->hostname);
63
64                         for(snode = n->subnet_tree->head; snode; snode = snext) {
65                                 snext = snode->next;
66                                 s = snode->data;
67                                 send_del_subnet(broadcast, s);
68                                 if(!strictsubnets)
69                                         subnet_del(n, s);
70                         }
71
72                         for(enode = n->edge_tree->head; enode; enode = enext) {
73                                 enext = enode->next;
74                                 e = enode->data;
75                                 if(!tunnelserver)
76                                         send_del_edge(broadcast, e);
77                                 edge_del(e);
78                         }
79                 }
80         }
81
82         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
83
84         for(nnode = node_tree->head; nnode; nnode = nnext) {
85                 nnext = nnode->next;
86                 n = nnode->data;
87
88                 if(!n->status.reachable) {
89                         for(enode = edge_weight_tree->head; enode; enode = enext) {
90                                 enext = enode->next;
91                                 e = enode->data;
92
93                                 if(e->to == n)
94                                         break;
95                         }
96
97                         if(!enode && (!strictsubnets || !n->subnet_tree->head))
98                                 /* in strictsubnets mode do not delete nodes with subnets */
99                                 node_del(n);
100                 }
101         }
102 }
103
104 /*
105   Terminate a connection:
106   - Close the socket
107   - Remove associated edge and tell other connections about it if report = true
108   - Check if we need to retry making an outgoing connection
109   - Deactivate the host
110 */
111 void terminate_connection(connection_t *c, bool report) {
112         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Closing connection with %s (%s)",
113                            c->name, c->hostname);
114
115         c->status.active = false;
116
117         if(c->node)
118                 c->node->connection = NULL;
119
120         if(c->edge) {
121                 if(report && !tunnelserver)
122                         send_del_edge(broadcast, c->edge);
123
124                 edge_del(c->edge);
125
126                 /* Run MST and SSSP algorithms */
127
128                 graph();
129
130                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
131
132                 if(report && !c->node->status.reachable) {
133                         edge_t *e;
134                         e = lookup_edge(c->node, myself);
135                         if(e) {
136                                 if(!tunnelserver)
137                                         send_del_edge(broadcast, e);
138                                 edge_del(e);
139                         }
140                 }
141         }
142
143         /* Check if this was our outgoing connection */
144
145         if(c->outgoing)
146                 retry_outgoing(c->outgoing);
147
148         connection_del(c);
149 }
150
151 /*
152   Check if the other end is active.
153   If we have sent packets, but didn't receive any,
154   then possibly the other end is dead. We send a
155   PING request over the meta connection. If the other
156   end does not reply in time, we consider them dead
157   and close the connection.
158 */
159 static void timeout_handler(int fd, short events, void *event) {
160         splay_node_t *node, *next;
161         connection_t *c;
162         time_t now = time(NULL);
163
164         for(node = connection_tree->head; node; node = next) {
165                 next = node->next;
166                 c = node->data;
167
168                 if(c->last_ping_time + pingtimeout <= now) {
169                         if(c->status.active) {
170                                 if(c->status.pinged) {
171                                         ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
172                                                            c->name, c->hostname, now - c->last_ping_time);
173                                         terminate_connection(c, true);
174                                         continue;
175                                 } else if(c->last_ping_time + pinginterval <= now) {
176                                         send_ping(c);
177                                 }
178                         } else {
179                                 if(c->status.connecting) {
180                                         ifdebug(CONNECTIONS)
181                                                 logger(LOG_WARNING, "Timeout while connecting to %s (%s)", c->name, c->hostname);
182                                         c->status.connecting = false;
183                                         closesocket(c->socket);
184                                         do_outgoing_connection(c);
185                                 } else {
186                                         ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication", c->name, c->hostname);
187                                         terminate_connection(c, false);
188                                         continue;
189                                 }
190                         }
191                 }
192         }
193
194         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
195                 logger(LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
196                 sleep(sleeptime);
197                 sleeptime *= 2;
198                 if(sleeptime < 0)
199                         sleeptime = 3600;
200         } else {
201                 sleeptime /= 2;
202                 if(sleeptime < 10)
203                         sleeptime = 10;
204         }
205
206         contradicting_add_edge = 0;
207         contradicting_del_edge = 0;
208
209         event_add(event, &(struct timeval){pingtimeout, 0});
210 }
211
212 void handle_meta_connection_data(int fd, short events, void *data) {
213         connection_t *c = data;
214         int result;
215         socklen_t len = sizeof result;
216
217         if(c->status.connecting) {
218                 c->status.connecting = false;
219
220                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
221
222                 if(!result)
223                         finish_connecting(c);
224                 else {
225                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
226                                            "Error while connecting to %s (%s): %s",
227                                            c->name, c->hostname, sockstrerror(result));
228                         closesocket(c->socket);
229                         do_outgoing_connection(c);
230                         return;
231                 }
232         }
233
234         if (!receive_meta(c)) {
235                 terminate_connection(c, c->status.active);
236                 return;
237         }
238 }
239
240 static void sigterm_handler(int signal, short events, void *data) {
241         logger(LOG_NOTICE, "Got %s signal", strsignal(signal));
242         event_loopexit(NULL);
243 }
244
245 static void sighup_handler(int signal, short events, void *data) {
246         logger(LOG_NOTICE, "Got %s signal", strsignal(signal));
247         reopenlogger();
248         reload_configuration();
249 }
250
251 static void sigalrm_handler(int signal, short events, void *data) {
252         logger(LOG_NOTICE, "Got %s signal", strsignal(signal));
253         retry();
254 }
255
256 int reload_configuration(void) {
257         connection_t *c;
258         splay_node_t *node, *next;
259         char *fname;
260         struct stat s;
261         static time_t last_config_check = 0;
262
263         /* Reread our own configuration file */
264
265         exit_configuration(&config_tree);
266         init_configuration(&config_tree);
267
268         if(!read_server_config()) {
269                 logger(LOG_ERR, "Unable to reread configuration file, exitting.");
270                 event_loopexit(NULL);
271                 return EINVAL;
272         }
273
274         /* Close connections to hosts that have a changed or deleted host config file */
275         
276         for(node = connection_tree->head; node; node = next) {
277                 c = node->data;
278                 next = node->next;
279                 
280                 if(c->outgoing) {
281                         free(c->outgoing->name);
282                         if(c->outgoing->ai)
283                                 freeaddrinfo(c->outgoing->ai);
284                         free(c->outgoing);
285                         c->outgoing = NULL;
286                 }
287                 
288                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
289                 if(stat(fname, &s) || s.st_mtime > last_config_check)
290                         terminate_connection(c, c->status.active);
291                 free(fname);
292         }
293
294         last_config_check = time(NULL);
295
296         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
297
298         if(strictsubnets) {
299                 subnet_t *subnet;
300
301
302                 for(node = subnet_tree->head; node; node = node->next) {
303                         subnet = node->data;
304                         subnet->expires = 1;
305                 }
306
307                 load_all_subnets();
308
309                 for(node = subnet_tree->head; node; node = next) {
310                         next = node->next;
311                         subnet = node->data;
312                         if(subnet->expires == 1) {
313                                 send_del_subnet(broadcast, subnet);
314                                 if(subnet->owner->status.reachable)
315                                         subnet_update(subnet->owner, subnet, false);
316                                 subnet_del(subnet->owner, subnet);
317                         } else if(subnet->expires == -1) {
318                                 subnet->expires = 0;
319                         } else {
320                                 send_add_subnet(broadcast, subnet);
321                                 if(subnet->owner->status.reachable)
322                                         subnet_update(subnet->owner, subnet, true);
323                         }
324                 }
325         }
326
327         /* Try to make outgoing connections */
328         
329         try_outgoing_connections();
330
331         return 0;
332 }
333
334 void retry(void) {
335         connection_t *c;
336         splay_node_t *node;
337
338         for(node = connection_tree->head; node; node = node->next) {
339                 c = node->data;
340                 
341                 if(c->outgoing && !c->node) {
342                         if(timeout_initialized(&c->outgoing->ev))
343                                 event_del(&c->outgoing->ev);
344                         if(c->status.connecting)
345                                 close(c->socket);
346                         c->outgoing->timeout = 0;
347                         do_outgoing_connection(c);
348                 }
349         }
350 }
351
352 /*
353   this is where it all happens...
354 */
355 int main_loop(void) {
356         struct event timeout_event;
357
358         timeout_set(&timeout_event, timeout_handler, &timeout_event);
359         event_add(&timeout_event, &(struct timeval){pingtimeout, 0});
360
361 #ifndef HAVE_MINGW
362         struct event sighup_event;
363         struct event sigterm_event;
364         struct event sigquit_event;
365         struct event sigalrm_event;
366
367         signal_set(&sighup_event, SIGHUP, sighup_handler, NULL);
368         signal_add(&sighup_event, NULL);
369         signal_set(&sigterm_event, SIGTERM, sigterm_handler, NULL);
370         signal_add(&sigterm_event, NULL);
371         signal_set(&sigquit_event, SIGQUIT, sigterm_handler, NULL);
372         signal_add(&sigquit_event, NULL);
373         signal_set(&sigalrm_event, SIGALRM, sigalrm_handler, NULL);
374         signal_add(&sigalrm_event, NULL);
375 #endif
376
377         if(event_loop(0) < 0) {
378                 logger(LOG_ERR, "Error while waiting for input: %s", strerror(errno));
379                 return 1;
380         }
381
382 #ifndef HAVE_MINGW
383         signal_del(&sighup_event);
384         signal_del(&sigterm_event);
385         signal_del(&sigquit_event);
386         signal_del(&sigalrm_event);
387 #endif
388
389         event_del(&timeout_event);
390
391         return 0;
392 }