git.meshlink.io Git - meshlink/blob - 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         if(c->node) {
 140                 c->node->out_meta += outlen;
 141                 mesh->self->out_meta += outlen;
 142         }
 143
 144         buffer_read(&c->outbuf, outlen);
 145
 146         if(!c->outbuf.len) {
 147                 io_set(&mesh->loop, &c->io, IO_READ);
 148         }
 149 }
 150
 151 void flush_meta(meshlink_handle_t *mesh, connection_t *c) {
 152         handle_meta_write(mesh, c);
 153 }
 154
 155 static void handle_meta_io(event_loop_t *loop, void *data, int flags) {
 156         meshlink_handle_t *mesh = loop->data;
 157         connection_t *c = data;
 158
 159         if(c->status.connecting) {
 160                 c->status.connecting = false;
 161
 162                 int result;
 163                 socklen_t len = sizeof(result);
 164                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 165
 166                 if(!result) {
 167                         finish_connecting(mesh, c);
 168                 } else {
 169                         logger(mesh, MESHLINK_ERROR, "Error while connecting to %s: %s", c->name, sockstrerror(result));
 170                         terminate_connection(mesh, c, false);
 171                         return;
 172                 }
 173         }
 174
 175         if(flags & IO_WRITE) {
 176                 handle_meta_write(mesh, c);
 177         } else {
 178                 handle_meta_connection_data(mesh, c);
 179         }
 180 }
 181
 182 // Find edges pointing to this node, and use them to build a list of unique, known addresses.
 183 static struct addrinfo *get_known_addresses(node_t *n) {
 184         struct addrinfo *ai = NULL;
 185
 186         for splay_each(edge_t, e, n->edge_tree) {
 187                 if(!e->reverse) {
 188                         continue;
 189                 }
 190
 191                 bool found = false;
 192
 193                 for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 194                         if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
 195                                 found = true;
 196                                 break;
 197                         }
 198                 }
 199
 200                 if(found) {
 201                         continue;
 202                 }
 203
 204                 // Create a new struct addrinfo, and put it at the head of the list.
 205                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(e->reverse->address.sa));
 206                 nai->ai_next = ai;
 207                 ai = nai;
 208
 209                 ai->ai_family = e->reverse->address.sa.sa_family;
 210                 ai->ai_socktype = SOCK_STREAM;
 211                 ai->ai_protocol = IPPROTO_TCP;
 212                 ai->ai_addrlen = SALEN(e->reverse->address.sa);
 213                 ai->ai_addr = (struct sockaddr *)(nai + 1);
 214                 memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
 215         }
 216
 217         return ai;
 218 }
 219
 220 // Build a list of recently seen addresses.
 221 static struct addrinfo *get_recent_addresses(node_t *n) {
 222         struct addrinfo *ai = NULL;
 223         struct addrinfo *aip;
 224
 225         for(int i = 0; i < 5; i++) {
 226                 if(!n->recent[i].sa.sa_family) {
 227                         break;
 228                 }
 229
 230                 // Create a new struct addrinfo, and put it at the end of the list.
 231                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(n->recent[i].sa));
 232
 233                 if(!ai) {
 234                         ai = nai;
 235                 } else {
 236                         aip->ai_next = nai;
 237                 }
 238
 239                 aip = nai;
 240
 241                 nai->ai_family = n->recent[i].sa.sa_family;
 242                 nai->ai_socktype = SOCK_STREAM;
 243                 nai->ai_protocol = IPPROTO_TCP;
 244                 nai->ai_addrlen = SALEN(n->recent[i].sa);
 245                 nai->ai_addr = (struct sockaddr *)(nai + 1);
 246                 memcpy(nai->ai_addr, &n->recent[i], nai->ai_addrlen);
 247         }
 248
 249         return ai;
 250 }
 251
 252 // Free struct addrinfo list from get_known_addresses().
 253 static void free_known_addresses(struct addrinfo *ai) {
 254         for(struct addrinfo *aip = ai, *next; aip; aip = next) {
 255                 next = aip->ai_next;
 256                 free(aip);
 257         }
 258 }
 259
 260 static void canonical_resolve_cb(meshlink_handle_t *mesh, char *host, char *serv, void *data, struct addrinfo *ai, int err) {
 261         (void)serv;
 262         (void)err;
 263         node_t *n = data;
 264
 265         free(host);
 266         free(serv);
 267
 268         for list_each(outgoing_t, outgoing, mesh->outgoings) {
 269                 if(outgoing->node == n) {
 270                         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 271                                 outgoing->ai = ai;
 272                                 outgoing->aip = NULL;
 273                                 outgoing->state = OUTGOING_CANONICAL;
 274                                 do_outgoing_connection(mesh, outgoing);
 275                         }
 276
 277                         return;
 278                 }
 279         }
 280 }
 281
 282 static bool get_next_outgoing_address(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 283         (void)mesh;
 284
 285         bool start = false;
 286
 287         if(outgoing->state == OUTGOING_START) {
 288                 start = true;
 289                 outgoing->state = OUTGOING_CANONICAL_RESOLVE;
 290         }
 291
 292         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 293                 node_t *n = outgoing->node;
 294
 295                 if(n->canonical_address) {
 296                         char *address = xstrdup(n->canonical_address);
 297                         char *port = strchr(address, ' ');
 298
 299                         if(port) {
 300                                 *port++ = 0;
 301                                 port = xstrdup(port);
 302                                 adns_queue(mesh, address, port, canonical_resolve_cb, outgoing->node, 2);
 303                                 return false;
 304                         } else {
 305                                 logger(mesh, MESHLINK_ERROR, "Canonical address for %s is missing port number", n->name);
 306                                 free(address);
 307                                 outgoing->state = OUTGOING_RECENT;
 308                         }
 309
 310                 } else {
 311                         outgoing->state = OUTGOING_RECENT;
 312                 }
 313         }
 314
 315         if(outgoing->state == OUTGOING_CANONICAL) {
 316                 if(!outgoing->aip) {
 317                         outgoing->aip = outgoing->ai;
 318                 } else {
 319                         outgoing->aip = outgoing->aip->ai_next;
 320                 }
 321
 322                 if(outgoing->aip) {
 323                         return true;
 324                 }
 325
 326                 if(outgoing->ai) {
 327                         freeaddrinfo(outgoing->ai);
 328                 }
 329
 330                 outgoing->ai = NULL;
 331                 outgoing->aip = NULL;
 332                 outgoing->state = OUTGOING_END;
 333         }
 334
 335         if(outgoing->state == OUTGOING_RECENT) {
 336                 if(!outgoing->aip) {
 337                         outgoing->ai = get_recent_addresses(outgoing->node);
 338                         outgoing->aip = outgoing->ai;
 339                 } else {
 340                         outgoing->aip = outgoing->aip->ai_next;
 341                 }
 342
 343                 if(outgoing->aip) {
 344                         return true;
 345                 }
 346
 347                 free_known_addresses(outgoing->ai);
 348                 outgoing->ai = NULL;
 349                 outgoing->aip = NULL;
 350                 outgoing->state = OUTGOING_KNOWN;
 351         }
 352
 353         if(outgoing->state == OUTGOING_KNOWN) {
 354                 if(!outgoing->aip) {
 355                         outgoing->ai = get_known_addresses(outgoing->node);
 356                         outgoing->aip = outgoing->ai;
 357                 } else {
 358                         outgoing->aip = outgoing->aip->ai_next;
 359                 }
 360
 361                 if(outgoing->aip) {
 362                         return true;
 363                 }
 364
 365                 free_known_addresses(outgoing->ai);
 366                 outgoing->ai = NULL;
 367                 outgoing->aip = NULL;
 368                 outgoing->state = OUTGOING_END;
 369         }
 370
 371         if(start) {
 372                 outgoing->state = OUTGOING_NO_KNOWN_ADDRESSES;
 373         }
 374
 375         return false;
 376 }
 377
 378 void do_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 379 begin:
 380
 381         if(!get_next_outgoing_address(mesh, outgoing)) {
 382                 if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 383                         /* We are waiting for a callback from the ADNS thread */
 384                 } else if(outgoing->state == OUTGOING_NO_KNOWN_ADDRESSES) {
 385                         logger(mesh, MESHLINK_ERROR, "No known addresses for %s", outgoing->node->name);
 386                         list_delete(mesh->outgoings, outgoing);
 387                 } else {
 388                         logger(mesh, MESHLINK_ERROR, "Could not set up a meta connection to %s", outgoing->node->name);
 389                         retry_outgoing(mesh, outgoing);
 390                 }
 391
 392                 return;
 393         }
 394
 395         connection_t *c = new_connection();
 396         c->outgoing = outgoing;
 397
 398         memcpy(&c->address, outgoing->aip->ai_addr, outgoing->aip->ai_addrlen);
 399
 400         if(mesh->log_level <= MESHLINK_INFO) {
 401                 char *hostname = sockaddr2hostname(&c->address);
 402                 logger(mesh, MESHLINK_INFO, "Trying to connect to %s at %s", outgoing->node->name, hostname);
 403                 free(hostname);
 404         }
 405
 406         c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 407
 408         if(c->socket == -1) {
 409                 if(mesh->log_level <= MESHLINK_ERROR) {
 410                         char *hostname = sockaddr2hostname(&c->address);
 411                         logger(mesh, MESHLINK_ERROR, "Creating socket for %s at %s failed: %s", c->name, hostname, sockstrerror(sockerrno));
 412                         free(hostname);
 413                 }
 414
 415                 free_connection(c);
 416                 goto begin;
 417         }
 418
 419         configure_tcp(c);
 420
 421 #ifdef FD_CLOEXEC
 422         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
 423 #endif
 424
 425 #if defined(IPV6_V6ONLY)
 426
 427         if(c->address.sa.sa_family == AF_INET6) {
 428                 static const int option = 1;
 429                 setsockopt(c->socket, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
 430         }
 431
 432 #endif
 433
 434         /* Connect */
 435
 436         int result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
 437
 438         if(result == -1 && !sockinprogress(sockerrno)) {
 439                 if(mesh->log_level <= MESHLINK_ERROR) {
 440                         char *hostname = sockaddr2hostname(&c->address);
 441                         logger(mesh, MESHLINK_ERROR, "Could not connect to %s: %s", outgoing->node->name, sockstrerror(sockerrno));
 442                         free(hostname);
 443                 }
 444
 445                 free_connection(c);
 446                 goto begin;
 447         }
 448
 449         /* Now that there is a working socket, fill in the rest and register this connection. */
 450
 451         c->status.connecting = true;
 452         c->status.initiator = true;
 453         c->name = xstrdup(outgoing->node->name);
 454         c->last_ping_time = mesh->loop.now.tv_sec;
 455
 456         connection_add(mesh, c);
 457
 458         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ | IO_WRITE);
 459 }
 460
 461 void reset_outgoing(outgoing_t *outgoing) {
 462         if(outgoing->ai) {
 463                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 464                         free_known_addresses(outgoing->ai);
 465                 } else {
 466                         freeaddrinfo(outgoing->ai);
 467                 }
 468         }
 469
 470         outgoing->ai = NULL;
 471         outgoing->aip = NULL;
 472         outgoing->state = OUTGOING_START;
 473 }
 474
 475 void setup_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 476         timeout_del(&mesh->loop, &outgoing->ev);
 477
 478         if(outgoing->node->connection) {
 479                 logger(mesh, MESHLINK_INFO, "Already connected to %s", outgoing->node->name);
 480
 481                 outgoing->node->connection->outgoing = outgoing;
 482                 return;
 483         }
 484
 485         reset_outgoing(outgoing);
 486
 487         if(outgoing->node->status.blacklisted) {
 488                 return;
 489         }
 490
 491         if(mesh->connection_try_cb) {
 492                 mesh->connection_try_cb(mesh, (meshlink_node_t *)outgoing->node);
 493         }
 494
 495         do_outgoing_connection(mesh, outgoing);
 496 }
 497
 498 /// Delayed close of a filedescriptor.
 499 static void tarpit(meshlink_handle_t *mesh, int fd) {
 500         if(!fd) {
 501                 return;
 502         }
 503
 504         if(mesh->pits[mesh->next_pit]) {
 505                 closesocket(mesh->pits[mesh->next_pit]);
 506         }
 507
 508         mesh->pits[mesh->next_pit++] = fd;
 509
 510         if(mesh->next_pit >= (int)(sizeof mesh->pits / sizeof mesh->pits[0])) {
 511                 mesh->next_pit = 0;
 512         }
 513 }
 514
 515 /*
 516   accept a new tcp connect and create a
 517   new connection
 518 */
 519 void handle_new_meta_connection(event_loop_t *loop, void *data, int flags) {
 520         (void)flags;
 521         meshlink_handle_t *mesh = loop->data;
 522         listen_socket_t *l = data;
 523         connection_t *c;
 524         sockaddr_t sa;
 525         int fd;
 526         socklen_t len = sizeof(sa);
 527
 528         memset(&sa, 0, sizeof(sa));
 529
 530         fd = accept(l->tcp.fd, &sa.sa, &len);
 531
 532         if(fd < 0) {
 533                 if(sockwouldblock(errno)) {
 534                         return;
 535                 }
 536
 537                 if(errno == EINVAL) { // TODO: check if Windows agrees
 538                         event_loop_stop(loop);
 539                         return;
 540                 }
 541
 542                 logger(mesh, MESHLINK_ERROR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 543                 return;
 544         }
 545
 546         sockaddrunmap(&sa);
 547
 548         /* Rate limit incoming connections to max_connection_burst/second. */
 549
 550         if(mesh->loop.now.tv_sec != mesh->connection_burst_time) {
 551                 mesh->connection_burst_time = mesh->loop.now.tv_sec;
 552                 mesh->connection_burst = 0;
 553         }
 554
 555         if(mesh->connection_burst >= max_connection_burst) {
 556                 tarpit(mesh, fd);
 557                 return;
 558         }
 559
 560         mesh->connection_burst++;
 561
 562         // Accept the new connection
 563
 564         c = new_connection();
 565         c->name = xstrdup("<unknown>");
 566
 567         c->address = sa;
 568         c->socket = fd;
 569         c->last_ping_time = mesh->loop.now.tv_sec;
 570
 571         char *hostname = sockaddr2hostname(&sa);
 572         logger(mesh, MESHLINK_INFO, "Connection from %s", hostname);
 573         free(hostname);
 574
 575         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
 576
 577         configure_tcp(c);
 578
 579         connection_add(mesh, c);
 580
 581         c->allow_request = ID;
 582         send_id(mesh, c);
 583 }
 584
 585 static void free_outgoing(outgoing_t *outgoing) {
 586         meshlink_handle_t *mesh = outgoing->node->mesh;
 587
 588         timeout_del(&mesh->loop, &outgoing->ev);
 589
 590         if(outgoing->ai) {
 591                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 592                         free_known_addresses(outgoing->ai);
 593                 } else {
 594                         freeaddrinfo(outgoing->ai);
 595                 }
 596         }
 597
 598         free(outgoing);
 599 }
 600
 601 void init_outgoings(meshlink_handle_t *mesh) {
 602         mesh->outgoings = list_alloc((list_action_t)free_outgoing);
 603 }
 604
 605 void exit_outgoings(meshlink_handle_t *mesh) {
 606         if(mesh->outgoings) {
 607                 list_delete_list(mesh->outgoings);
 608                 mesh->outgoings = NULL;
 609         }
 610 }