]> git.meshlink.io Git - meshlink/blob - src/net_socket.c
Fix cornercases closing channels.
[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 static void handle_meta_io(event_loop_t *loop, void *data, int flags) {
147         meshlink_handle_t *mesh = loop->data;
148         connection_t *c = data;
149
150         if(c->status.connecting) {
151                 c->status.connecting = false;
152
153                 int result;
154                 socklen_t len = sizeof(result);
155                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
156
157                 if(!result) {
158                         finish_connecting(mesh, c);
159                 } else {
160                         logger(mesh, MESHLINK_DEBUG, "Error while connecting to %s: %s", c->name, sockstrerror(result));
161                         terminate_connection(mesh, c, false);
162                         return;
163                 }
164         }
165
166         if(flags & IO_WRITE) {
167                 handle_meta_write(mesh, c);
168         } else {
169                 handle_meta_connection_data(mesh, c);
170         }
171 }
172
173 // Find edges pointing to this node, and use them to build a list of unique, known addresses.
174 static struct addrinfo *get_known_addresses(node_t *n) {
175         struct addrinfo *ai = NULL;
176
177         for splay_each(edge_t, e, n->edge_tree) {
178                 if(!e->reverse) {
179                         continue;
180                 }
181
182                 bool found = false;
183
184                 for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
185                         if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
186                                 found = true;
187                                 break;
188                         }
189                 }
190
191                 if(found) {
192                         continue;
193                 }
194
195                 // Create a new struct addrinfo, and put it at the head of the list.
196                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(e->reverse->address.sa));
197                 nai->ai_next = ai;
198                 ai = nai;
199
200                 ai->ai_family = e->reverse->address.sa.sa_family;
201                 ai->ai_socktype = SOCK_STREAM;
202                 ai->ai_protocol = IPPROTO_TCP;
203                 ai->ai_addrlen = SALEN(e->reverse->address.sa);
204                 ai->ai_addr = (struct sockaddr *)(nai + 1);
205                 memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
206         }
207
208         return ai;
209 }
210
211 // Build a list of recently seen addresses.
212 static struct addrinfo *get_recent_addresses(node_t *n) {
213         struct addrinfo *ai = NULL;
214         struct addrinfo *aip;
215
216         for(int i = 0; i < 5; i++) {
217                 if(!n->recent[i].sa.sa_family) {
218                         break;
219                 }
220
221                 // Create a new struct addrinfo, and put it at the end of the list.
222                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(n->recent[i].sa));
223
224                 if(!ai) {
225                         ai = nai;
226                 } else {
227                         aip->ai_next = nai;
228                 }
229
230                 aip = nai;
231
232                 nai->ai_family = n->recent[i].sa.sa_family;
233                 nai->ai_socktype = SOCK_STREAM;
234                 nai->ai_protocol = IPPROTO_TCP;
235                 nai->ai_addrlen = SALEN(n->recent[i].sa);
236                 nai->ai_addr = (struct sockaddr *)(nai + 1);
237                 memcpy(nai->ai_addr, &n->recent[i], nai->ai_addrlen);
238         }
239
240         return ai;
241 }
242
243 // Free struct addrinfo list from get_known_addresses().
244 static void free_known_addresses(struct addrinfo *ai) {
245         for(struct addrinfo *aip = ai, *next; aip; aip = next) {
246                 next = aip->ai_next;
247                 free(aip);
248         }
249 }
250
251 static void canonical_resolve_cb(meshlink_handle_t *mesh, char *host, char *serv, void *data, struct addrinfo *ai, int err) {
252         (void)serv;
253         (void)err;
254         node_t *n = data;
255
256         free(host);
257         free(serv);
258
259         for list_each(outgoing_t, outgoing, mesh->outgoings) {
260                 if(outgoing->node == n) {
261                         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
262                                 outgoing->ai = ai;
263                                 outgoing->aip = NULL;
264                                 outgoing->state = OUTGOING_CANONICAL;
265                                 do_outgoing_connection(mesh, outgoing);
266                         }
267
268                         return;
269                 }
270         }
271 }
272
273 static bool get_next_outgoing_address(meshlink_handle_t *mesh, outgoing_t *outgoing) {
274         (void)mesh;
275
276         bool start = false;
277
278         if(outgoing->state == OUTGOING_START) {
279                 start = true;
280                 outgoing->state = OUTGOING_CANONICAL_RESOLVE;
281         }
282
283         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
284                 node_t *n = outgoing->node;
285
286                 if(n->canonical_address) {
287                         char *address = xstrdup(n->canonical_address);
288                         char *port = strchr(address, ' ');
289
290                         if(port) {
291                                 *port++ = 0;
292                                 port = xstrdup(port);
293                                 adns_queue(mesh, address, port, canonical_resolve_cb, outgoing->node, 2);
294                                 return false;
295                         } else {
296                                 logger(mesh, MESHLINK_ERROR, "Canonical address for %s is missing port number", n->name);
297                                 free(address);
298                                 outgoing->state = OUTGOING_RECENT;
299                         }
300
301                 } else {
302                         outgoing->state = OUTGOING_RECENT;
303                 }
304         }
305
306         if(outgoing->state == OUTGOING_CANONICAL) {
307                 if(!outgoing->aip) {
308                         outgoing->aip = outgoing->ai;
309                 } else {
310                         outgoing->aip = outgoing->aip->ai_next;
311                 }
312
313                 if(outgoing->aip) {
314                         return true;
315                 }
316
317                 if(outgoing->ai) {
318                         freeaddrinfo(outgoing->ai);
319                 }
320
321                 outgoing->ai = NULL;
322                 outgoing->aip = NULL;
323                 outgoing->state = OUTGOING_END;
324         }
325
326         if(outgoing->state == OUTGOING_RECENT) {
327                 if(!outgoing->aip) {
328                         outgoing->ai = get_recent_addresses(outgoing->node);
329                         outgoing->aip = outgoing->ai;
330                 } else {
331                         outgoing->aip = outgoing->aip->ai_next;
332                 }
333
334                 if(outgoing->aip) {
335                         return true;
336                 }
337
338                 free_known_addresses(outgoing->ai);
339                 outgoing->ai = NULL;
340                 outgoing->aip = NULL;
341                 outgoing->state = OUTGOING_KNOWN;
342         }
343
344         if(outgoing->state == OUTGOING_KNOWN) {
345                 if(!outgoing->aip) {
346                         outgoing->ai = get_known_addresses(outgoing->node);
347                         outgoing->aip = outgoing->ai;
348                 } else {
349                         outgoing->aip = outgoing->aip->ai_next;
350                 }
351
352                 if(outgoing->aip) {
353                         return true;
354                 }
355
356                 free_known_addresses(outgoing->ai);
357                 outgoing->ai = NULL;
358                 outgoing->aip = NULL;
359                 outgoing->state = OUTGOING_END;
360         }
361
362         if(start) {
363                 outgoing->state = OUTGOING_NO_KNOWN_ADDRESSES;
364         }
365
366         return false;
367 }
368
369 void do_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
370 begin:
371
372         if(!get_next_outgoing_address(mesh, outgoing)) {
373                 if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
374                         /* We are waiting for a callback from the ADNS thread */
375                 } else if(outgoing->state == OUTGOING_NO_KNOWN_ADDRESSES) {
376                         logger(mesh, MESHLINK_ERROR, "No known addresses for %s", outgoing->node->name);
377                 } else {
378                         logger(mesh, MESHLINK_ERROR, "Could not set up a meta connection to %s", outgoing->node->name);
379                         retry_outgoing(mesh, outgoing);
380                 }
381
382                 return;
383         }
384
385         connection_t *c = new_connection();
386         c->outgoing = outgoing;
387
388         memcpy(&c->address, outgoing->aip->ai_addr, outgoing->aip->ai_addrlen);
389
390         if(mesh->log_level <= MESHLINK_INFO) {
391                 char *hostname = sockaddr2hostname(&c->address);
392                 logger(mesh, MESHLINK_INFO, "Trying to connect to %s at %s", outgoing->node->name, hostname);
393                 free(hostname);
394         }
395
396         c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
397
398         if(c->socket == -1) {
399                 if(mesh->log_level <= MESHLINK_ERROR) {
400                         char *hostname = sockaddr2hostname(&c->address);
401                         logger(mesh, MESHLINK_ERROR, "Creating socket for %s at %s failed: %s", c->name, hostname, sockstrerror(sockerrno));
402                         free(hostname);
403                 }
404
405                 free_connection(c);
406                 goto begin;
407         }
408
409         configure_tcp(c);
410
411 #ifdef FD_CLOEXEC
412         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
413 #endif
414
415 #if defined(IPV6_V6ONLY)
416
417         if(c->address.sa.sa_family == AF_INET6) {
418                 static const int option = 1;
419                 setsockopt(c->socket, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
420         }
421
422 #endif
423
424         /* Connect */
425
426         int result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
427
428         if(result == -1 && !sockinprogress(sockerrno)) {
429                 if(mesh->log_level <= MESHLINK_ERROR) {
430                         char *hostname = sockaddr2hostname(&c->address);
431                         logger(mesh, MESHLINK_ERROR, "Could not connect to %s: %s", outgoing->node->name, sockstrerror(sockerrno));
432                         free(hostname);
433                 }
434
435                 free_connection(c);
436                 goto begin;
437         }
438
439         /* Now that there is a working socket, fill in the rest and register this connection. */
440
441         c->status.connecting = true;
442         c->status.initiator = true;
443         c->name = xstrdup(outgoing->node->name);
444         c->last_ping_time = mesh->loop.now.tv_sec;
445
446         connection_add(mesh, c);
447
448         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ | IO_WRITE);
449 }
450
451 void reset_outgoing(outgoing_t *outgoing) {
452         if(outgoing->ai) {
453                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
454                         free_known_addresses(outgoing->ai);
455                 } else {
456                         freeaddrinfo(outgoing->ai);
457                 }
458         }
459
460         outgoing->ai = NULL;
461         outgoing->aip = NULL;
462         outgoing->state = OUTGOING_START;
463 }
464
465 void setup_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
466         timeout_del(&mesh->loop, &outgoing->ev);
467
468         if(outgoing->node->connection) {
469                 logger(mesh, MESHLINK_INFO, "Already connected to %s", outgoing->node->name);
470
471                 outgoing->node->connection->outgoing = outgoing;
472                 return;
473         }
474
475         reset_outgoing(outgoing);
476
477         if(outgoing->node->status.blacklisted) {
478                 return;
479         }
480
481         if(mesh->connection_try_cb) {
482                 mesh->connection_try_cb(mesh, (meshlink_node_t *)outgoing->node);
483         }
484
485         do_outgoing_connection(mesh, outgoing);
486 }
487
488 /// Delayed close of a filedescriptor.
489 static void tarpit(meshlink_handle_t *mesh, int fd) {
490         if(!fd) {
491                 return;
492         }
493
494         if(mesh->pits[mesh->next_pit]) {
495                 closesocket(mesh->pits[mesh->next_pit]);
496         }
497
498         mesh->pits[mesh->next_pit++] = fd;
499
500         if(mesh->next_pit >= (int)(sizeof mesh->pits / sizeof mesh->pits[0])) {
501                 mesh->next_pit = 0;
502         }
503 }
504
505 /*
506   accept a new tcp connect and create a
507   new connection
508 */
509 void handle_new_meta_connection(event_loop_t *loop, void *data, int flags) {
510         (void)flags;
511         meshlink_handle_t *mesh = loop->data;
512         listen_socket_t *l = data;
513         connection_t *c;
514         sockaddr_t sa;
515         int fd;
516         socklen_t len = sizeof(sa);
517
518         memset(&sa, 0, sizeof(sa));
519
520         fd = accept(l->tcp.fd, &sa.sa, &len);
521
522         if(fd < 0) {
523                 if(errno == EINVAL) { // TODO: check if Windows agrees
524                         event_loop_stop(loop);
525                         return;
526                 }
527
528                 logger(mesh, MESHLINK_ERROR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
529                 return;
530         }
531
532         sockaddrunmap(&sa);
533
534         /* Rate limit incoming connections to max_connection_burst/second. */
535
536         if(mesh->loop.now.tv_sec != mesh->connection_burst_time) {
537                 mesh->connection_burst_time = mesh->loop.now.tv_sec;
538                 mesh->connection_burst = 0;
539         }
540
541         if(mesh->connection_burst >= max_connection_burst) {
542                 tarpit(mesh, fd);
543                 return;
544         }
545
546         mesh->connection_burst++;
547
548         // Accept the new connection
549
550         c = new_connection();
551         c->name = xstrdup("<unknown>");
552
553         c->address = sa;
554         c->socket = fd;
555         c->last_ping_time = mesh->loop.now.tv_sec;
556
557         char *hostname = sockaddr2hostname(&sa);
558         logger(mesh, MESHLINK_INFO, "Connection from %s", hostname);
559         free(hostname);
560
561         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
562
563         configure_tcp(c);
564
565         connection_add(mesh, c);
566
567         c->allow_request = ID;
568         send_id(mesh, c);
569 }
570
571 static void free_outgoing(outgoing_t *outgoing) {
572         meshlink_handle_t *mesh = outgoing->node->mesh;
573
574         timeout_del(&mesh->loop, &outgoing->ev);
575
576         if(outgoing->ai) {
577                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
578                         free_known_addresses(outgoing->ai);
579                 } else {
580                         freeaddrinfo(outgoing->ai);
581                 }
582         }
583
584         free(outgoing);
585 }
586
587 void init_outgoings(meshlink_handle_t *mesh) {
588         mesh->outgoings = list_alloc((list_action_t)free_outgoing);
589 }
590
591 void exit_outgoings(meshlink_handle_t *mesh) {
592         if(mesh->outgoings) {
593                 list_delete_list(mesh->outgoings);
594                 mesh->outgoings = NULL;
595         }
596 }