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         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(errno == EINVAL) { // TODO: check if Windows agrees
 528                         event_loop_stop(loop);
 529                         return;
 530                 }
 531
 532                 logger(mesh, MESHLINK_ERROR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 533                 return;
 534         }
 535
 536         sockaddrunmap(&sa);
 537
 538         /* Rate limit incoming connections to max_connection_burst/second. */
 539
 540         if(mesh->loop.now.tv_sec != mesh->connection_burst_time) {
 541                 mesh->connection_burst_time = mesh->loop.now.tv_sec;
 542                 mesh->connection_burst = 0;
 543         }
 544
 545         if(mesh->connection_burst >= max_connection_burst) {
 546                 tarpit(mesh, fd);
 547                 return;
 548         }
 549
 550         mesh->connection_burst++;
 551
 552         // Accept the new connection
 553
 554         c = new_connection();
 555         c->name = xstrdup("<unknown>");
 556
 557         c->address = sa;
 558         c->socket = fd;
 559         c->last_ping_time = mesh->loop.now.tv_sec;
 560
 561         char *hostname = sockaddr2hostname(&sa);
 562         logger(mesh, MESHLINK_INFO, "Connection from %s", hostname);
 563         free(hostname);
 564
 565         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
 566
 567         configure_tcp(c);
 568
 569         connection_add(mesh, c);
 570
 571         c->allow_request = ID;
 572         send_id(mesh, c);
 573 }
 574
 575 static void free_outgoing(outgoing_t *outgoing) {
 576         meshlink_handle_t *mesh = outgoing->node->mesh;
 577
 578         timeout_del(&mesh->loop, &outgoing->ev);
 579
 580         if(outgoing->ai) {
 581                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 582                         free_known_addresses(outgoing->ai);
 583                 } else {
 584                         freeaddrinfo(outgoing->ai);
 585                 }
 586         }
 587
 588         free(outgoing);
 589 }
 590
 591 void init_outgoings(meshlink_handle_t *mesh) {
 592         mesh->outgoings = list_alloc((list_action_t)free_outgoing);
 593 }
 594
 595 void exit_outgoings(meshlink_handle_t *mesh) {
 596         if(mesh->outgoings) {
 597                 list_delete_list(mesh->outgoings);
 598                 mesh->outgoings = NULL;
 599         }
 600 }