]> git.meshlink.io Git - meshlink/blob - src/net_socket.c
Ensure we don't use external buffers after a channel is closed.
[meshlink] / src / net_socket.c
1 /*
2     net_socket.c -- Handle various kinds of sockets.
3     Copyright (C) 2014-2017 Guus Sliepen <guus@meshlink.io>
4
5     This program is free software; you can redistribute it and/or modify
6     it under the terms of the GNU General Public License as published by
7     the Free Software Foundation; either version 2 of the License, or
8     (at your option) any later version.
9
10     This program is distributed in the hope that it will be useful,
11     but WITHOUT ANY WARRANTY; without even the implied warranty of
12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13     GNU General Public License for more details.
14
15     You should have received a copy of the GNU General Public License along
16     with this program; if not, write to the Free Software Foundation, Inc.,
17     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20 #include "system.h"
21
22 #include "adns.h"
23 #include "conf.h"
24 #include "connection.h"
25 #include "list.h"
26 #include "logger.h"
27 #include "meshlink_internal.h"
28 #include "meta.h"
29 #include "net.h"
30 #include "netutl.h"
31 #include "protocol.h"
32 #include "utils.h"
33 #include "xalloc.h"
34
35 /* Needed on Mac OS/X */
36 #ifndef SOL_TCP
37 #define SOL_TCP IPPROTO_TCP
38 #endif
39
40 #ifndef MSG_NOSIGNAL
41 #define MSG_NOSIGNAL 0
42 #endif
43
44 static const int max_connection_burst = 100;
45
46 /* Setup sockets */
47
48 static void configure_tcp(connection_t *c) {
49 #ifdef O_NONBLOCK
50         int flags = fcntl(c->socket, F_GETFL);
51
52         if(fcntl(c->socket, F_SETFL, flags | O_NONBLOCK) < 0) {
53                 logger(c->mesh, MESHLINK_ERROR, "System call `%s' failed: %s", "fcntl", strerror(errno));
54         }
55
56 #elif defined(WIN32)
57         unsigned long arg = 1;
58
59         if(ioctlsocket(c->socket, FIONBIO, &arg) != 0) {
60                 logger(c->mesh, MESHLINK_ERROR, "System call `%s' failed: %s", "ioctlsocket", sockstrerror(sockerrno));
61         }
62
63 #endif
64
65 #if defined(SOL_TCP) && defined(TCP_NODELAY)
66         int nodelay = 1;
67         setsockopt(c->socket, SOL_TCP, TCP_NODELAY, (void *)&nodelay, sizeof(nodelay));
68 #endif
69
70 #if defined(IP_TOS) && defined(IPTOS_LOWDELAY)
71         int lowdelay = IPTOS_LOWDELAY;
72         setsockopt(c->socket, IPPROTO_IP, IP_TOS, (void *)&lowdelay, sizeof(lowdelay));
73 #endif
74
75 #if defined(SO_NOSIGPIPE)
76         int nosigpipe = 1;
77         setsockopt(c->socket, SOL_SOCKET, SO_NOSIGPIPE, (void *)&nosigpipe, sizeof(nosigpipe));
78 #endif
79 }
80
81 static void retry_outgoing_handler(event_loop_t *loop, void *data) {
82         assert(data);
83
84         meshlink_handle_t *mesh = loop->data;
85         outgoing_t *outgoing = data;
86         setup_outgoing_connection(mesh, outgoing);
87 }
88
89 void retry_outgoing(meshlink_handle_t *mesh, outgoing_t *outgoing) {
90         if(!mesh->reachable && mesh->loop.now.tv_sec < mesh->last_unreachable + mesh->dev_class_traits[outgoing->node->devclass].fast_retry_period) {
91                 outgoing->timeout = 1;
92         } else {
93                 outgoing->timeout += 5;
94         }
95
96         int maxtimeout = mesh->dev_class_traits[outgoing->node->devclass].maxtimeout;
97
98         if(outgoing->timeout > maxtimeout) {
99                 outgoing->timeout = maxtimeout;
100         }
101
102         timeout_add(&mesh->loop, &outgoing->ev, retry_outgoing_handler, outgoing, &(struct timespec) {
103                 outgoing->timeout, prng(mesh, TIMER_FUDGE)
104         });
105
106         logger(mesh, MESHLINK_INFO, "Trying to re-establish outgoing connection in %d seconds", outgoing->timeout);
107 }
108
109 void finish_connecting(meshlink_handle_t *mesh, connection_t *c) {
110         logger(mesh, MESHLINK_INFO, "Connected to %s", c->name);
111
112         c->last_ping_time = mesh->loop.now.tv_sec;
113         c->status.connecting = false;
114
115         send_id(mesh, c);
116 }
117
118 static void handle_meta_write(meshlink_handle_t *mesh, connection_t *c) {
119         if(c->outbuf.len <= c->outbuf.offset) {
120                 return;
121         }
122
123         ssize_t outlen = send(c->socket, c->outbuf.data + c->outbuf.offset, c->outbuf.len - c->outbuf.offset, MSG_NOSIGNAL);
124
125         if(outlen <= 0) {
126                 if(!errno || errno == EPIPE) {
127                         logger(mesh, MESHLINK_INFO, "Connection closed by %s", c->name);
128                 } else if(sockwouldblock(sockerrno)) {
129                         logger(mesh, MESHLINK_DEBUG, "Sending %lu bytes to %s would block", (unsigned long)(c->outbuf.len - c->outbuf.offset), c->name);
130                         return;
131                 } else {
132                         logger(mesh, MESHLINK_ERROR, "Could not send %lu bytes of data to %s: %s", (unsigned long)(c->outbuf.len - c->outbuf.offset), c->name, strerror(errno));
133                 }
134
135                 terminate_connection(mesh, c, c->status.active);
136                 return;
137         }
138
139         buffer_read(&c->outbuf, outlen);
140
141         if(!c->outbuf.len) {
142                 io_set(&mesh->loop, &c->io, IO_READ);
143         }
144 }
145
146 void flush_meta(meshlink_handle_t *mesh, connection_t *c) {
147         handle_meta_write(mesh, c);
148 }
149
150 static void handle_meta_io(event_loop_t *loop, void *data, int flags) {
151         meshlink_handle_t *mesh = loop->data;
152         connection_t *c = data;
153
154         if(c->status.connecting) {
155                 c->status.connecting = false;
156
157                 int result;
158                 socklen_t len = sizeof(result);
159                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
160
161                 if(!result) {
162                         finish_connecting(mesh, c);
163                 } else {
164                         logger(mesh, MESHLINK_DEBUG, "Error while connecting to %s: %s", c->name, sockstrerror(result));
165                         terminate_connection(mesh, c, false);
166                         return;
167                 }
168         }
169
170         if(flags & IO_WRITE) {
171                 handle_meta_write(mesh, c);
172         } else {
173                 handle_meta_connection_data(mesh, c);
174         }
175 }
176
177 // Find edges pointing to this node, and use them to build a list of unique, known addresses.
178 static struct addrinfo *get_known_addresses(node_t *n) {
179         struct addrinfo *ai = NULL;
180
181         for splay_each(edge_t, e, n->edge_tree) {
182                 if(!e->reverse) {
183                         continue;
184                 }
185
186                 bool found = false;
187
188                 for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
189                         if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
190                                 found = true;
191                                 break;
192                         }
193                 }
194
195                 if(found) {
196                         continue;
197                 }
198
199                 // Create a new struct addrinfo, and put it at the head of the list.
200                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(e->reverse->address.sa));
201                 nai->ai_next = ai;
202                 ai = nai;
203
204                 ai->ai_family = e->reverse->address.sa.sa_family;
205                 ai->ai_socktype = SOCK_STREAM;
206                 ai->ai_protocol = IPPROTO_TCP;
207                 ai->ai_addrlen = SALEN(e->reverse->address.sa);
208                 ai->ai_addr = (struct sockaddr *)(nai + 1);
209                 memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
210         }
211
212         return ai;
213 }
214
215 // Build a list of recently seen addresses.
216 static struct addrinfo *get_recent_addresses(node_t *n) {
217         struct addrinfo *ai = NULL;
218         struct addrinfo *aip;
219
220         for(int i = 0; i < 5; i++) {
221                 if(!n->recent[i].sa.sa_family) {
222                         break;
223                 }
224
225                 // Create a new struct addrinfo, and put it at the end of the list.
226                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(n->recent[i].sa));
227
228                 if(!ai) {
229                         ai = nai;
230                 } else {
231                         aip->ai_next = nai;
232                 }
233
234                 aip = nai;
235
236                 nai->ai_family = n->recent[i].sa.sa_family;
237                 nai->ai_socktype = SOCK_STREAM;
238                 nai->ai_protocol = IPPROTO_TCP;
239                 nai->ai_addrlen = SALEN(n->recent[i].sa);
240                 nai->ai_addr = (struct sockaddr *)(nai + 1);
241                 memcpy(nai->ai_addr, &n->recent[i], nai->ai_addrlen);
242         }
243
244         return ai;
245 }
246
247 // Free struct addrinfo list from get_known_addresses().
248 static void free_known_addresses(struct addrinfo *ai) {
249         for(struct addrinfo *aip = ai, *next; aip; aip = next) {
250                 next = aip->ai_next;
251                 free(aip);
252         }
253 }
254
255 static void canonical_resolve_cb(meshlink_handle_t *mesh, char *host, char *serv, void *data, struct addrinfo *ai, int err) {
256         (void)serv;
257         (void)err;
258         node_t *n = data;
259
260         free(host);
261         free(serv);
262
263         for list_each(outgoing_t, outgoing, mesh->outgoings) {
264                 if(outgoing->node == n) {
265                         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
266                                 outgoing->ai = ai;
267                                 outgoing->aip = NULL;
268                                 outgoing->state = OUTGOING_CANONICAL;
269                                 do_outgoing_connection(mesh, outgoing);
270                         }
271
272                         return;
273                 }
274         }
275 }
276
277 static bool get_next_outgoing_address(meshlink_handle_t *mesh, outgoing_t *outgoing) {
278         (void)mesh;
279
280         bool start = false;
281
282         if(outgoing->state == OUTGOING_START) {
283                 start = true;
284                 outgoing->state = OUTGOING_CANONICAL_RESOLVE;
285         }
286
287         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
288                 node_t *n = outgoing->node;
289
290                 if(n->canonical_address) {
291                         char *address = xstrdup(n->canonical_address);
292                         char *port = strchr(address, ' ');
293
294                         if(port) {
295                                 *port++ = 0;
296                                 port = xstrdup(port);
297                                 adns_queue(mesh, address, port, canonical_resolve_cb, outgoing->node, 2);
298                                 return false;
299                         } else {
300                                 logger(mesh, MESHLINK_ERROR, "Canonical address for %s is missing port number", n->name);
301                                 free(address);
302                                 outgoing->state = OUTGOING_RECENT;
303                         }
304
305                 } else {
306                         outgoing->state = OUTGOING_RECENT;
307                 }
308         }
309
310         if(outgoing->state == OUTGOING_CANONICAL) {
311                 if(!outgoing->aip) {
312                         outgoing->aip = outgoing->ai;
313                 } else {
314                         outgoing->aip = outgoing->aip->ai_next;
315                 }
316
317                 if(outgoing->aip) {
318                         return true;
319                 }
320
321                 if(outgoing->ai) {
322                         freeaddrinfo(outgoing->ai);
323                 }
324
325                 outgoing->ai = NULL;
326                 outgoing->aip = NULL;
327                 outgoing->state = OUTGOING_END;
328         }
329
330         if(outgoing->state == OUTGOING_RECENT) {
331                 if(!outgoing->aip) {
332                         outgoing->ai = get_recent_addresses(outgoing->node);
333                         outgoing->aip = outgoing->ai;
334                 } else {
335                         outgoing->aip = outgoing->aip->ai_next;
336                 }
337
338                 if(outgoing->aip) {
339                         return true;
340                 }
341
342                 free_known_addresses(outgoing->ai);
343                 outgoing->ai = NULL;
344                 outgoing->aip = NULL;
345                 outgoing->state = OUTGOING_KNOWN;
346         }
347
348         if(outgoing->state == OUTGOING_KNOWN) {
349                 if(!outgoing->aip) {
350                         outgoing->ai = get_known_addresses(outgoing->node);
351                         outgoing->aip = outgoing->ai;
352                 } else {
353                         outgoing->aip = outgoing->aip->ai_next;
354                 }
355
356                 if(outgoing->aip) {
357                         return true;
358                 }
359
360                 free_known_addresses(outgoing->ai);
361                 outgoing->ai = NULL;
362                 outgoing->aip = NULL;
363                 outgoing->state = OUTGOING_END;
364         }
365
366         if(start) {
367                 outgoing->state = OUTGOING_NO_KNOWN_ADDRESSES;
368         }
369
370         return false;
371 }
372
373 void do_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
374 begin:
375
376         if(!get_next_outgoing_address(mesh, outgoing)) {
377                 if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
378                         /* We are waiting for a callback from the ADNS thread */
379                 } else if(outgoing->state == OUTGOING_NO_KNOWN_ADDRESSES) {
380                         logger(mesh, MESHLINK_ERROR, "No known addresses for %s", outgoing->node->name);
381                 } else {
382                         logger(mesh, MESHLINK_ERROR, "Could not set up a meta connection to %s", outgoing->node->name);
383                         retry_outgoing(mesh, outgoing);
384                 }
385
386                 return;
387         }
388
389         connection_t *c = new_connection();
390         c->outgoing = outgoing;
391
392         memcpy(&c->address, outgoing->aip->ai_addr, outgoing->aip->ai_addrlen);
393
394         if(mesh->log_level <= MESHLINK_INFO) {
395                 char *hostname = sockaddr2hostname(&c->address);
396                 logger(mesh, MESHLINK_INFO, "Trying to connect to %s at %s", outgoing->node->name, hostname);
397                 free(hostname);
398         }
399
400         c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
401
402         if(c->socket == -1) {
403                 if(mesh->log_level <= MESHLINK_ERROR) {
404                         char *hostname = sockaddr2hostname(&c->address);
405                         logger(mesh, MESHLINK_ERROR, "Creating socket for %s at %s failed: %s", c->name, hostname, sockstrerror(sockerrno));
406                         free(hostname);
407                 }
408
409                 free_connection(c);
410                 goto begin;
411         }
412
413         configure_tcp(c);
414
415 #ifdef FD_CLOEXEC
416         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
417 #endif
418
419 #if defined(IPV6_V6ONLY)
420
421         if(c->address.sa.sa_family == AF_INET6) {
422                 static const int option = 1;
423                 setsockopt(c->socket, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
424         }
425
426 #endif
427
428         /* Connect */
429
430         int result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
431
432         if(result == -1 && !sockinprogress(sockerrno)) {
433                 if(mesh->log_level <= MESHLINK_ERROR) {
434                         char *hostname = sockaddr2hostname(&c->address);
435                         logger(mesh, MESHLINK_ERROR, "Could not connect to %s: %s", outgoing->node->name, sockstrerror(sockerrno));
436                         free(hostname);
437                 }
438
439                 free_connection(c);
440                 goto begin;
441         }
442
443         /* Now that there is a working socket, fill in the rest and register this connection. */
444
445         c->status.connecting = true;
446         c->status.initiator = true;
447         c->name = xstrdup(outgoing->node->name);
448         c->last_ping_time = mesh->loop.now.tv_sec;
449
450         connection_add(mesh, c);
451
452         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ | IO_WRITE);
453 }
454
455 void reset_outgoing(outgoing_t *outgoing) {
456         if(outgoing->ai) {
457                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
458                         free_known_addresses(outgoing->ai);
459                 } else {
460                         freeaddrinfo(outgoing->ai);
461                 }
462         }
463
464         outgoing->ai = NULL;
465         outgoing->aip = NULL;
466         outgoing->state = OUTGOING_START;
467 }
468
469 void setup_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
470         timeout_del(&mesh->loop, &outgoing->ev);
471
472         if(outgoing->node->connection) {
473                 logger(mesh, MESHLINK_INFO, "Already connected to %s", outgoing->node->name);
474
475                 outgoing->node->connection->outgoing = outgoing;
476                 return;
477         }
478
479         reset_outgoing(outgoing);
480
481         if(outgoing->node->status.blacklisted) {
482                 return;
483         }
484
485         if(mesh->connection_try_cb) {
486                 mesh->connection_try_cb(mesh, (meshlink_node_t *)outgoing->node);
487         }
488
489         do_outgoing_connection(mesh, outgoing);
490 }
491
492 /// Delayed close of a filedescriptor.
493 static void tarpit(meshlink_handle_t *mesh, int fd) {
494         if(!fd) {
495                 return;
496         }
497
498         if(mesh->pits[mesh->next_pit]) {
499                 closesocket(mesh->pits[mesh->next_pit]);
500         }
501
502         mesh->pits[mesh->next_pit++] = fd;
503
504         if(mesh->next_pit >= (int)(sizeof mesh->pits / sizeof mesh->pits[0])) {
505                 mesh->next_pit = 0;
506         }
507 }
508
509 /*
510   accept a new tcp connect and create a
511   new connection
512 */
513 void handle_new_meta_connection(event_loop_t *loop, void *data, int flags) {
514         (void)flags;
515         meshlink_handle_t *mesh = loop->data;
516         listen_socket_t *l = data;
517         connection_t *c;
518         sockaddr_t sa;
519         int fd;
520         socklen_t len = sizeof(sa);
521
522         memset(&sa, 0, sizeof(sa));
523
524         fd = accept(l->tcp.fd, &sa.sa, &len);
525
526         if(fd < 0) {
527                 if(sockwouldblock(errno)) {
528                         return;
529                 }
530
531                 if(errno == EINVAL) { // TODO: check if Windows agrees
532                         event_loop_stop(loop);
533                         return;
534                 }
535
536                 logger(mesh, MESHLINK_ERROR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
537                 return;
538         }
539
540         sockaddrunmap(&sa);
541
542         /* Rate limit incoming connections to max_connection_burst/second. */
543
544         if(mesh->loop.now.tv_sec != mesh->connection_burst_time) {
545                 mesh->connection_burst_time = mesh->loop.now.tv_sec;
546                 mesh->connection_burst = 0;
547         }
548
549         if(mesh->connection_burst >= max_connection_burst) {
550                 tarpit(mesh, fd);
551                 return;
552         }
553
554         mesh->connection_burst++;
555
556         // Accept the new connection
557
558         c = new_connection();
559         c->name = xstrdup("<unknown>");
560
561         c->address = sa;
562         c->socket = fd;
563         c->last_ping_time = mesh->loop.now.tv_sec;
564
565         char *hostname = sockaddr2hostname(&sa);
566         logger(mesh, MESHLINK_INFO, "Connection from %s", hostname);
567         free(hostname);
568
569         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
570
571         configure_tcp(c);
572
573         connection_add(mesh, c);
574
575         c->allow_request = ID;
576         send_id(mesh, c);
577 }
578
579 static void free_outgoing(outgoing_t *outgoing) {
580         meshlink_handle_t *mesh = outgoing->node->mesh;
581
582         timeout_del(&mesh->loop, &outgoing->ev);
583
584         if(outgoing->ai) {
585                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
586                         free_known_addresses(outgoing->ai);
587                 } else {
588                         freeaddrinfo(outgoing->ai);
589                 }
590         }
591
592         free(outgoing);
593 }
594
595 void init_outgoings(meshlink_handle_t *mesh) {
596         mesh->outgoings = list_alloc((list_action_t)free_outgoing);
597 }
598
599 void exit_outgoings(meshlink_handle_t *mesh) {
600         if(mesh->outgoings) {
601                 list_delete_list(mesh->outgoings);
602                 mesh->outgoings = NULL;
603         }
604 }