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