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[mesh->devclass].fast_retry_period) {
  91                 outgoing->timeout = 1;
  92         } else {
  93                 outgoing->timeout += 5;
  94         }
  95
  96         if(outgoing->timeout > mesh->dev_class_traits[mesh->devclass].maxtimeout) {
  97                 outgoing->timeout = mesh->dev_class_traits[mesh->devclass].maxtimeout;
  98         }
  99
 100         timeout_add(&mesh->loop, &outgoing->ev, retry_outgoing_handler, outgoing, &(struct timespec) {
 101                 outgoing->timeout, prng(mesh, TIMER_FUDGE)
 102         });
 103
 104         logger(mesh, MESHLINK_INFO, "Trying to re-establish outgoing connection in %d seconds", outgoing->timeout);
 105 }
 106
 107 void finish_connecting(meshlink_handle_t *mesh, connection_t *c) {
 108         logger(mesh, MESHLINK_INFO, "Connected to %s", c->name);
 109
 110         c->last_ping_time = mesh->loop.now.tv_sec;
 111         c->status.connecting = false;
 112
 113         send_id(mesh, c);
 114 }
 115
 116 static void handle_meta_write(meshlink_handle_t *mesh, connection_t *c) {
 117         if(c->outbuf.len <= c->outbuf.offset) {
 118                 return;
 119         }
 120
 121         ssize_t outlen = send(c->socket, c->outbuf.data + c->outbuf.offset, c->outbuf.len - c->outbuf.offset, MSG_NOSIGNAL);
 122
 123         if(outlen <= 0) {
 124                 if(!errno || errno == EPIPE) {
 125                         logger(mesh, MESHLINK_INFO, "Connection closed by %s", c->name);
 126                 } else if(sockwouldblock(sockerrno)) {
 127                         logger(mesh, MESHLINK_DEBUG, "Sending %lu bytes to %s would block", (unsigned long)(c->outbuf.len - c->outbuf.offset), c->name);
 128                         return;
 129                 } else {
 130                         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));
 131                 }
 132
 133                 terminate_connection(mesh, c, c->status.active);
 134                 return;
 135         }
 136
 137         buffer_read(&c->outbuf, outlen);
 138
 139         if(!c->outbuf.len) {
 140                 io_set(&mesh->loop, &c->io, IO_READ);
 141         }
 142 }
 143
 144 static void handle_meta_io(event_loop_t *loop, void *data, int flags) {
 145         meshlink_handle_t *mesh = loop->data;
 146         connection_t *c = data;
 147
 148         if(c->status.connecting) {
 149                 c->status.connecting = false;
 150
 151                 int result;
 152                 socklen_t len = sizeof(result);
 153                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 154
 155                 if(!result) {
 156                         finish_connecting(mesh, c);
 157                 } else {
 158                         logger(mesh, MESHLINK_DEBUG, "Error while connecting to %s: %s", c->name, sockstrerror(result));
 159                         terminate_connection(mesh, c, false);
 160                         return;
 161                 }
 162         }
 163
 164         if(flags & IO_WRITE) {
 165                 handle_meta_write(mesh, c);
 166         } else {
 167                 handle_meta_connection_data(mesh, c);
 168         }
 169 }
 170
 171 // Find edges pointing to this node, and use them to build a list of unique, known addresses.
 172 static struct addrinfo *get_known_addresses(node_t *n) {
 173         struct addrinfo *ai = NULL;
 174
 175         for splay_each(edge_t, e, n->edge_tree) {
 176                 if(!e->reverse) {
 177                         continue;
 178                 }
 179
 180                 bool found = false;
 181
 182                 for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 183                         if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
 184                                 found = true;
 185                                 break;
 186                         }
 187                 }
 188
 189                 if(found) {
 190                         continue;
 191                 }
 192
 193                 // Create a new struct addrinfo, and put it at the head of the list.
 194                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(e->reverse->address.sa));
 195                 nai->ai_next = ai;
 196                 ai = nai;
 197
 198                 ai->ai_family = e->reverse->address.sa.sa_family;
 199                 ai->ai_socktype = SOCK_STREAM;
 200                 ai->ai_protocol = IPPROTO_TCP;
 201                 ai->ai_addrlen = SALEN(e->reverse->address.sa);
 202                 ai->ai_addr = (struct sockaddr *)(nai + 1);
 203                 memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
 204         }
 205
 206         return ai;
 207 }
 208
 209 // Build a list of recently seen addresses.
 210 static struct addrinfo *get_recent_addresses(node_t *n) {
 211         struct addrinfo *ai = NULL;
 212         struct addrinfo *aip;
 213
 214         for(int i = 0; i < 5; i++) {
 215                 if(!n->recent[i].sa.sa_family) {
 216                         break;
 217                 }
 218
 219                 // Create a new struct addrinfo, and put it at the end of the list.
 220                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(n->recent[i].sa));
 221
 222                 if(!ai) {
 223                         ai = nai;
 224                 } else {
 225                         aip->ai_next = nai;
 226                 }
 227
 228                 aip = nai;
 229
 230                 nai->ai_family = n->recent[i].sa.sa_family;
 231                 nai->ai_socktype = SOCK_STREAM;
 232                 nai->ai_protocol = IPPROTO_TCP;
 233                 nai->ai_addrlen = SALEN(n->recent[i].sa);
 234                 nai->ai_addr = (struct sockaddr *)(nai + 1);
 235                 memcpy(nai->ai_addr, &n->recent[i], nai->ai_addrlen);
 236         }
 237
 238         return ai;
 239 }
 240
 241 // Free struct addrinfo list from get_known_addresses().
 242 static void free_known_addresses(struct addrinfo *ai) {
 243         for(struct addrinfo *aip = ai, *next; aip; aip = next) {
 244                 next = aip->ai_next;
 245                 free(aip);
 246         }
 247 }
 248
 249 static void canonical_resolve_cb(meshlink_handle_t *mesh, char *host, char *serv, void *data, struct addrinfo *ai, int err) {
 250         (void)serv;
 251         (void)err;
 252         node_t *n = data;
 253
 254         free(host);
 255         free(serv);
 256
 257         for list_each(outgoing_t, outgoing, mesh->outgoings) {
 258                 if(outgoing->node == n) {
 259                         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 260                                 outgoing->ai = ai;
 261                                 outgoing->aip = NULL;
 262                                 outgoing->state = OUTGOING_CANONICAL;
 263                                 do_outgoing_connection(mesh, outgoing);
 264                         }
 265
 266                         return;
 267                 }
 268         }
 269 }
 270
 271 static bool get_next_outgoing_address(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 272         (void)mesh;
 273
 274         bool start = false;
 275
 276         if(outgoing->state == OUTGOING_START) {
 277                 start = true;
 278                 outgoing->state = OUTGOING_CANONICAL_RESOLVE;
 279         }
 280
 281         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 282                 node_t *n = outgoing->node;
 283
 284                 if(n->canonical_address) {
 285                         char *address = xstrdup(n->canonical_address);
 286                         char *port = strchr(address, ' ');
 287
 288                         if(port) {
 289                                 *port++ = 0;
 290                                 port = xstrdup(port);
 291                                 adns_queue(mesh, address, port, canonical_resolve_cb, outgoing->node, 2);
 292                                 return false;
 293                         } else {
 294                                 logger(mesh, MESHLINK_ERROR, "Canonical address for %s is missing port number", n->name);
 295                                 free(address);
 296                                 outgoing->state = OUTGOING_RECENT;
 297                         }
 298
 299                 } else {
 300                         outgoing->state = OUTGOING_RECENT;
 301                 }
 302         }
 303
 304         if(outgoing->state == OUTGOING_CANONICAL) {
 305                 if(!outgoing->aip) {
 306                         outgoing->aip = outgoing->ai;
 307                 } else {
 308                         outgoing->aip = outgoing->aip->ai_next;
 309                 }
 310
 311                 if(outgoing->aip) {
 312                         return true;
 313                 }
 314
 315                 if(outgoing->ai) {
 316                         freeaddrinfo(outgoing->ai);
 317                 }
 318
 319                 outgoing->ai = NULL;
 320                 outgoing->aip = NULL;
 321                 outgoing->state = OUTGOING_RECENT;
 322         }
 323
 324         if(outgoing->state == OUTGOING_RECENT) {
 325                 if(!outgoing->aip) {
 326                         outgoing->ai = get_recent_addresses(outgoing->node);
 327                         outgoing->aip = outgoing->ai;
 328                 } else {
 329                         outgoing->aip = outgoing->aip->ai_next;
 330                 }
 331
 332                 if(outgoing->aip) {
 333                         return true;
 334                 }
 335
 336                 free_known_addresses(outgoing->ai);
 337                 outgoing->ai = NULL;
 338                 outgoing->aip = NULL;
 339                 outgoing->state = OUTGOING_KNOWN;
 340         }
 341
 342         if(outgoing->state == OUTGOING_KNOWN) {
 343                 if(!outgoing->aip) {
 344                         outgoing->ai = get_known_addresses(outgoing->node);
 345                         outgoing->aip = outgoing->ai;
 346                 } else {
 347                         outgoing->aip = outgoing->aip->ai_next;
 348                 }
 349
 350                 if(outgoing->aip) {
 351                         return true;
 352                 }
 353
 354                 free_known_addresses(outgoing->ai);
 355                 outgoing->ai = NULL;
 356                 outgoing->aip = NULL;
 357                 outgoing->state = OUTGOING_END;
 358         }
 359
 360         if(start) {
 361                 outgoing->state = OUTGOING_NO_KNOWN_ADDRESSES;
 362         }
 363
 364         return false;
 365 }
 366
 367 void do_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 368 begin:
 369
 370         if(!get_next_outgoing_address(mesh, outgoing)) {
 371                 if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 372                         /* We are waiting for a callback from the ADNS thread */
 373                 } else if(outgoing->state == OUTGOING_NO_KNOWN_ADDRESSES) {
 374                         logger(mesh, MESHLINK_ERROR, "No known addresses for %s", outgoing->node->name);
 375                 } else {
 376                         logger(mesh, MESHLINK_ERROR, "Could not set up a meta connection to %s", outgoing->node->name);
 377                         retry_outgoing(mesh, outgoing);
 378                 }
 379
 380                 return;
 381         }
 382
 383         connection_t *c = new_connection();
 384         c->outgoing = outgoing;
 385
 386         memcpy(&c->address, outgoing->aip->ai_addr, outgoing->aip->ai_addrlen);
 387
 388         if(mesh->log_level <= MESHLINK_INFO) {
 389                 char *hostname = sockaddr2hostname(&c->address);
 390                 logger(mesh, MESHLINK_INFO, "Trying to connect to %s at %s", outgoing->node->name, hostname);
 391                 free(hostname);
 392         }
 393
 394         c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 395
 396         if(c->socket == -1) {
 397                 if(mesh->log_level <= MESHLINK_ERROR) {
 398                         char *hostname = sockaddr2hostname(&c->address);
 399                         logger(mesh, MESHLINK_ERROR, "Creating socket for %s at %s failed: %s", c->name, hostname, sockstrerror(sockerrno));
 400                         free(hostname);
 401                 }
 402
 403                 free_connection(c);
 404                 goto begin;
 405         }
 406
 407         configure_tcp(c);
 408
 409 #ifdef FD_CLOEXEC
 410         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
 411 #endif
 412
 413 #if defined(IPV6_V6ONLY)
 414
 415         if(c->address.sa.sa_family == AF_INET6) {
 416                 static const int option = 1;
 417                 setsockopt(c->socket, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
 418         }
 419
 420 #endif
 421
 422         /* Connect */
 423
 424         int result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
 425
 426         if(result == -1 && !sockinprogress(sockerrno)) {
 427                 if(mesh->log_level <= MESHLINK_ERROR) {
 428                         char *hostname = sockaddr2hostname(&c->address);
 429                         logger(mesh, MESHLINK_ERROR, "Could not connect to %s: %s", outgoing->node->name, sockstrerror(sockerrno));
 430                         free(hostname);
 431                 }
 432
 433                 free_connection(c);
 434                 goto begin;
 435         }
 436
 437         /* Now that there is a working socket, fill in the rest and register this connection. */
 438
 439         c->status.connecting = true;
 440         c->status.initiator = true;
 441         c->name = xstrdup(outgoing->node->name);
 442         c->last_ping_time = mesh->loop.now.tv_sec;
 443
 444         connection_add(mesh, c);
 445
 446         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ | IO_WRITE);
 447 }
 448
 449 void reset_outgoing(outgoing_t *outgoing) {
 450         if(outgoing->ai) {
 451                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 452                         free_known_addresses(outgoing->ai);
 453                 } else {
 454                         freeaddrinfo(outgoing->ai);
 455                 }
 456         }
 457
 458         outgoing->ai = NULL;
 459         outgoing->aip = NULL;
 460         outgoing->state = OUTGOING_START;
 461 }
 462
 463 void setup_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 464         timeout_del(&mesh->loop, &outgoing->ev);
 465
 466         if(outgoing->node->connection) {
 467                 logger(mesh, MESHLINK_INFO, "Already connected to %s", outgoing->node->name);
 468
 469                 outgoing->node->connection->outgoing = outgoing;
 470                 return;
 471         }
 472
 473         reset_outgoing(outgoing);
 474
 475         if(outgoing->node->status.blacklisted) {
 476                 return;
 477         }
 478
 479         if(mesh->connection_try_cb) {
 480                 mesh->connection_try_cb(mesh, (meshlink_node_t *)outgoing->node);
 481         }
 482
 483         do_outgoing_connection(mesh, outgoing);
 484 }
 485
 486 /// Delayed close of a filedescriptor.
 487 static void tarpit(meshlink_handle_t *mesh, int fd) {
 488         if(!fd) {
 489                 return;
 490         }
 491
 492         if(mesh->pits[mesh->next_pit]) {
 493                 closesocket(mesh->pits[mesh->next_pit]);
 494         }
 495
 496         mesh->pits[mesh->next_pit++] = fd;
 497
 498         if(mesh->next_pit >= (int)(sizeof mesh->pits / sizeof mesh->pits[0])) {
 499                 mesh->next_pit = 0;
 500         }
 501 }
 502
 503 /*
 504   accept a new tcp connect and create a
 505   new connection
 506 */
 507 void handle_new_meta_connection(event_loop_t *loop, void *data, int flags) {
 508         (void)flags;
 509         meshlink_handle_t *mesh = loop->data;
 510         listen_socket_t *l = data;
 511         connection_t *c;
 512         sockaddr_t sa;
 513         int fd;
 514         socklen_t len = sizeof(sa);
 515
 516         memset(&sa, 0, sizeof(sa));
 517
 518         fd = accept(l->tcp.fd, &sa.sa, &len);
 519
 520         if(fd < 0) {
 521                 if(errno == EINVAL) { // TODO: check if Windows agrees
 522                         event_loop_stop(loop);
 523                         return;
 524                 }
 525
 526                 logger(mesh, MESHLINK_ERROR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 527                 return;
 528         }
 529
 530         sockaddrunmap(&sa);
 531
 532         /* Rate limit incoming connections to max_connection_burst/second. */
 533
 534         if(mesh->loop.now.tv_sec != mesh->connection_burst_time) {
 535                 mesh->connection_burst_time = mesh->loop.now.tv_sec;
 536                 mesh->connection_burst = 0;
 537         }
 538
 539         if(mesh->connection_burst >= max_connection_burst) {
 540                 tarpit(mesh, fd);
 541                 return;
 542         }
 543
 544         mesh->connection_burst++;
 545
 546         // Accept the new connection
 547
 548         c = new_connection();
 549         c->name = xstrdup("<unknown>");
 550
 551         c->address = sa;
 552         c->socket = fd;
 553         c->last_ping_time = mesh->loop.now.tv_sec;
 554
 555         char *hostname = sockaddr2hostname(&sa);
 556         logger(mesh, MESHLINK_INFO, "Connection from %s", hostname);
 557         free(hostname);
 558
 559         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
 560
 561         configure_tcp(c);
 562
 563         connection_add(mesh, c);
 564
 565         c->allow_request = ID;
 566         send_id(mesh, c);
 567 }
 568
 569 static void free_outgoing(outgoing_t *outgoing) {
 570         meshlink_handle_t *mesh = outgoing->node->mesh;
 571
 572         timeout_del(&mesh->loop, &outgoing->ev);
 573
 574         if(outgoing->ai) {
 575                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 576                         free_known_addresses(outgoing->ai);
 577                 } else {
 578                         freeaddrinfo(outgoing->ai);
 579                 }
 580         }
 581
 582         free(outgoing);
 583 }
 584
 585 void init_outgoings(meshlink_handle_t *mesh) {
 586         mesh->outgoings = list_alloc((list_action_t)free_outgoing);
 587 }
 588
 589 void exit_outgoings(meshlink_handle_t *mesh) {
 590         if(mesh->outgoings) {
 591                 list_delete_list(mesh->outgoings);
 592                 mesh->outgoings = NULL;
 593         }
 594 }