Better length checks.
[tinc] / src / net.c
1 /*
2     net.c -- most of the network code
3     Copyright (C) 1998-2003 Ivo Timmermans <ivo@o2w.nl>,
4                   2000-2003 Guus Sliepen <guus@sliepen.eu.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
17     along with this program; if not, write to the Free Software
18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19
20     $Id: net.c,v 1.35.4.200 2003/08/28 21:05:10 guus Exp $
21 */
22
23 #include "system.h"
24
25 #include <openssl/rand.h>
26
27 #include "utils.h"
28 #include "avl_tree.h"
29 #include "conf.h"
30 #include "connection.h"
31 #include "device.h"
32 #include "event.h"
33 #include "graph.h"
34 #include "logger.h"
35 #include "meta.h"
36 #include "net.h"
37 #include "netutl.h"
38 #include "process.h"
39 #include "protocol.h"
40 #include "route.h"
41 #include "subnet.h"
42 #include "xalloc.h"
43
44 bool do_purge = false;
45 volatile bool running = false;
46
47 time_t now = 0;
48
49 /* Purge edges and subnets of unreachable nodes. Use carefully. */
50
51 static void purge(void)
52 {
53         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
54         node_t *n;
55         edge_t *e;
56         subnet_t *s;
57
58         cp();
59
60         ifdebug(PROTOCOL) logger(LOG_DEBUG, _("Purging unreachable nodes"));
61
62         /* Remove all edges and subnets owned by unreachable nodes. */
63
64         for(nnode = node_tree->head; nnode; nnode = nnext) {
65                 nnext = nnode->next;
66                 n = nnode->data;
67
68                 if(!n->status.reachable) {
69                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Purging node %s (%s)"), n->name,
70                                            n->hostname);
71
72                         for(snode = n->subnet_tree->head; snode; snode = snext) {
73                                 snext = snode->next;
74                                 s = snode->data;
75                                 send_del_subnet(broadcast, s);
76                                 subnet_del(n, s);
77                         }
78
79                         for(enode = n->edge_tree->head; enode; enode = enext) {
80                                 enext = enode->next;
81                                 e = enode->data;
82                                 send_del_edge(broadcast, e);
83                                 edge_del(e);
84                         }
85                 }
86         }
87
88         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
89
90         for(nnode = node_tree->head; nnode; nnode = nnext) {
91                 nnext = nnode->next;
92                 n = nnode->data;
93
94                 if(!n->status.reachable) {
95                         for(enode = edge_weight_tree->head; enode; enode = enext) {
96                                 enext = enode->next;
97                                 e = enode->data;
98
99                                 if(e->to == n)
100                                         break;
101                         }
102
103                         if(!enode)
104                                 node_del(n);
105                 }
106         }
107 }
108
109 /*
110   put all file descriptors in an fd_set array
111   While we're at it, purge stuff that needs to be removed.
112 */
113 static int build_fdset(fd_set * fs)
114 {
115         avl_node_t *node, *next;
116         connection_t *c;
117         int i, max = 0;
118
119         cp();
120
121         FD_ZERO(fs);
122
123         for(node = connection_tree->head; node; node = next) {
124                 next = node->next;
125                 c = node->data;
126
127                 if(c->status.remove) {
128                         connection_del(c);
129                         if(!connection_tree->head)
130                                 purge();
131                 } else {
132                         FD_SET(c->socket, fs);
133                         if(c->socket > max)
134                                 max = c->socket;
135                 }
136         }
137
138         for(i = 0; i < listen_sockets; i++) {
139                 FD_SET(listen_socket[i].tcp, fs);
140                 if(listen_socket[i].tcp > max)
141                         max = listen_socket[i].tcp;
142                 FD_SET(listen_socket[i].udp, fs);
143                 if(listen_socket[i].udp > max)
144                         max = listen_socket[i].udp;
145         }
146
147         FD_SET(device_fd, fs);
148         if(device_fd > max)
149                 max = device_fd;
150         
151         return max;
152 }
153
154 /*
155   Terminate a connection:
156   - Close the socket
157   - Remove associated edge and tell other connections about it if report = true
158   - Check if we need to retry making an outgoing connection
159   - Deactivate the host
160 */
161 void terminate_connection(connection_t *c, bool report)
162 {
163         cp();
164
165         if(c->status.remove)
166                 return;
167
168         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
169                            c->name, c->hostname);
170
171         c->status.remove = true;
172         c->status.active = false;
173
174         if(c->node)
175                 c->node->connection = NULL;
176
177         if(c->socket)
178                 closesocket(c->socket);
179
180         if(c->edge) {
181                 if(report)
182                         send_del_edge(broadcast, c->edge);
183
184                 edge_del(c->edge);
185
186                 /* Run MST and SSSP algorithms */
187
188                 graph();
189
190                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
191
192                 if(report && !c->node->status.reachable) {
193                         edge_t *e;
194                         e = lookup_edge(c->node, myself);
195                         if(e) {
196                                 send_del_edge(broadcast, e);
197                                 edge_del(e);
198                         }
199                 }
200         }
201
202         /* Check if this was our outgoing connection */
203
204         if(c->outgoing) {
205                 retry_outgoing(c->outgoing);
206                 c->outgoing = NULL;
207         }
208 }
209
210 /*
211   Check if the other end is active.
212   If we have sent packets, but didn't receive any,
213   then possibly the other end is dead. We send a
214   PING request over the meta connection. If the other
215   end does not reply in time, we consider them dead
216   and close the connection.
217 */
218 static void check_dead_connections(void)
219 {
220         avl_node_t *node, *next;
221         connection_t *c;
222
223         cp();
224
225         for(node = connection_tree->head; node; node = next) {
226                 next = node->next;
227                 c = node->data;
228
229                 if(c->last_ping_time + pingtimeout < now) {
230                         if(c->status.active) {
231                                 if(c->status.pinged) {
232                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING"),
233                                                            c->name, c->hostname);
234                                         c->status.timeout = true;
235                                         terminate_connection(c, true);
236                                 } else {
237                                         send_ping(c);
238                                 }
239                         } else {
240                                 if(c->status.remove) {
241                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
242                                                    c->name, c->hostname, *(uint32_t *)&c->status);
243                                         connection_del(c);
244                                         continue;
245                                 }
246                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
247                                                    c->name, c->hostname);
248                                 terminate_connection(c, false);
249                         }
250                 }
251         }
252 }
253
254 /*
255   check all connections to see if anything
256   happened on their sockets
257 */
258 static void check_network_activity(fd_set * f)
259 {
260         connection_t *c;
261         avl_node_t *node;
262         int result, i;
263         int len = sizeof(result);
264         vpn_packet_t packet;
265
266         cp();
267
268         if(FD_ISSET(device_fd, f)) {
269                 if(read_packet(&packet))
270                         route_outgoing(&packet);
271         }
272
273         for(node = connection_tree->head; node; node = node->next) {
274                 c = node->data;
275
276                 if(c->status.remove)
277                         continue;
278
279                 if(FD_ISSET(c->socket, f)) {
280                         if(c->status.connecting) {
281                                 c->status.connecting = false;
282                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
283
284                                 if(!result)
285                                         finish_connecting(c);
286                                 else {
287                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
288                                                            _("Error while connecting to %s (%s): %s"),
289                                                            c->name, c->hostname, strerror(result));
290                                         closesocket(c->socket);
291                                         do_outgoing_connection(c);
292                                         continue;
293                                 }
294                         }
295
296                         if(!receive_meta(c)) {
297                                 terminate_connection(c, c->status.active);
298                                 continue;
299                         }
300                 }
301         }
302
303         for(i = 0; i < listen_sockets; i++) {
304                 if(FD_ISSET(listen_socket[i].udp, f))
305                         handle_incoming_vpn_data(listen_socket[i].udp);
306
307                 if(FD_ISSET(listen_socket[i].tcp, f))
308                         handle_new_meta_connection(listen_socket[i].tcp);
309         }
310 }
311
312 /*
313   this is where it all happens...
314 */
315 int main_loop(void)
316 {
317         fd_set fset;
318         struct timeval tv;
319         int r, maxfd;
320         time_t last_ping_check, last_config_check;
321         event_t *event;
322
323         cp();
324
325         last_ping_check = now;
326         last_config_check = now;
327         srand(now);
328
329         running = true;
330
331         while(running) {
332                 now = time(NULL);
333
334                 tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
335                 tv.tv_usec = 0;
336
337                 maxfd = build_fdset(&fset);
338
339                 r = select(maxfd + 1, &fset, NULL, NULL, &tv);
340
341                 if(r < 0) {
342                         if(errno != EINTR && errno != EAGAIN) {
343                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
344                                            strerror(errno));
345                                 cp_trace();
346                                 dump_connections();
347                                 return 1;
348                         }
349
350                         continue;
351                 }
352
353                 check_network_activity(&fset);
354
355                 if(do_purge) {
356                         purge();
357                         do_purge = false;
358                 }
359
360                 /* Let's check if everybody is still alive */
361
362                 if(last_ping_check + pingtimeout < now) {
363                         check_dead_connections();
364                         last_ping_check = now;
365
366                         if(routing_mode == RMODE_SWITCH)
367                                 age_mac();
368
369                         age_past_requests();
370
371                         /* Should we regenerate our key? */
372
373                         if(keyexpires < now) {
374                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
375
376                                 RAND_pseudo_bytes(myself->key, myself->keylength);
377                                 if(myself->cipher)
378                                         EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key, myself->key + myself->cipher->key_len);
379                                 send_key_changed(broadcast, myself);
380                                 keyexpires = now + keylifetime;
381                         }
382                 }
383
384
385                 while((event = get_expired_event())) {
386                         event->handler(event->data);
387                         free(event);
388                 }
389
390                 if(sigalrm) {
391                         logger(LOG_INFO, _("Flushing event queue"));
392
393                         while(event_tree->head) {
394                                 event = event_tree->head->data;
395                                 event->handler(event->data);
396                                 event_del(event);
397                         }
398                         sigalrm = false;
399                 }
400
401                 if(sighup) {
402                         connection_t *c;
403                         avl_node_t *node;
404                         char *fname;
405                         struct stat s;
406                         
407                         sighup = false;
408                         
409                         /* Reread our own configuration file */
410
411                         exit_configuration(&config_tree);
412                         init_configuration(&config_tree);
413
414                         if(!read_server_config()) {
415                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
416                                 return 1;
417                         }
418
419                         /* Close connections to hosts that have a changed or deleted host config file */
420                         
421                         for(node = connection_tree->head; node; node = node->next) {
422                                 c = node->data;
423                                 
424                                 if(c->outgoing) {
425                                         free(c->outgoing->name);
426                                         freeaddrinfo(c->outgoing->ai);
427                                         free(c->outgoing);
428                                         c->outgoing = NULL;
429                                 }
430                                 
431                                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
432                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
433                                         terminate_connection(c, c->status.active);
434                                 free(fname);
435                         }
436
437                         last_config_check = now;
438
439                         /* Try to make outgoing connections */
440                         
441                         try_outgoing_connections();
442                 }
443         }
444
445         return 0;
446 }