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 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_RECENT;
 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 }