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
  76 static void retry_outgoing_handler(event_loop_t *loop, void *data) {
  77         assert(data);
  78
  79         meshlink_handle_t *mesh = loop->data;
  80         outgoing_t *outgoing = data;
  81         setup_outgoing_connection(mesh, outgoing);
  82 }
  83
  84 void retry_outgoing(meshlink_handle_t *mesh, outgoing_t *outgoing) {
  85         if(!mesh->reachable && mesh->loop.now.tv_sec < mesh->last_unreachable + mesh->dev_class_traits[mesh->devclass].fast_retry_period) {
  86                 outgoing->timeout = 1;
  87         } else {
  88                 outgoing->timeout += 5;
  89         }
  90
  91         if(outgoing->timeout > mesh->maxtimeout) {
  92                 outgoing->timeout = mesh->maxtimeout;
  93         }
  94
  95         timeout_add(&mesh->loop, &outgoing->ev, retry_outgoing_handler, outgoing, &(struct timespec) {
  96                 outgoing->timeout, prng(mesh, TIMER_FUDGE)
  97         });
  98
  99         logger(mesh, MESHLINK_INFO, "Trying to re-establish outgoing connection in %d seconds", outgoing->timeout);
 100 }
 101
 102 void finish_connecting(meshlink_handle_t *mesh, connection_t *c) {
 103         logger(mesh, MESHLINK_INFO, "Connected to %s", c->name);
 104
 105         c->last_ping_time = mesh->loop.now.tv_sec;
 106         c->status.connecting = false;
 107
 108         send_id(mesh, c);
 109 }
 110
 111 static void handle_meta_write(meshlink_handle_t *mesh, connection_t *c) {
 112         if(c->outbuf.len <= c->outbuf.offset) {
 113                 return;
 114         }
 115
 116         ssize_t outlen = send(c->socket, c->outbuf.data + c->outbuf.offset, c->outbuf.len - c->outbuf.offset, MSG_NOSIGNAL);
 117
 118         if(outlen <= 0) {
 119                 if(!errno || errno == EPIPE) {
 120                         logger(mesh, MESHLINK_INFO, "Connection closed by %s", c->name);
 121                 } else if(sockwouldblock(sockerrno)) {
 122                         logger(mesh, MESHLINK_DEBUG, "Sending %lu bytes to %s would block", (unsigned long)(c->outbuf.len - c->outbuf.offset), c->name);
 123                         return;
 124                 } else {
 125                         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));
 126                 }
 127
 128                 terminate_connection(mesh, c, c->status.active);
 129                 return;
 130         }
 131
 132         buffer_read(&c->outbuf, outlen);
 133
 134         if(!c->outbuf.len) {
 135                 io_set(&mesh->loop, &c->io, IO_READ);
 136         }
 137 }
 138
 139 static void handle_meta_io(event_loop_t *loop, void *data, int flags) {
 140         meshlink_handle_t *mesh = loop->data;
 141         connection_t *c = data;
 142
 143         if(c->status.connecting) {
 144                 c->status.connecting = false;
 145
 146                 int result;
 147                 socklen_t len = sizeof(result);
 148                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 149
 150                 if(!result) {
 151                         finish_connecting(mesh, c);
 152                 } else {
 153                         logger(mesh, MESHLINK_DEBUG, "Error while connecting to %s: %s", c->name, sockstrerror(result));
 154                         terminate_connection(mesh, c, false);
 155                         return;
 156                 }
 157         }
 158
 159         if(flags & IO_WRITE) {
 160                 handle_meta_write(mesh, c);
 161         } else {
 162                 handle_meta_connection_data(mesh, c);
 163         }
 164 }
 165
 166 // Find edges pointing to this node, and use them to build a list of unique, known addresses.
 167 static struct addrinfo *get_known_addresses(node_t *n) {
 168         struct addrinfo *ai = NULL;
 169
 170         for splay_each(edge_t, e, n->edge_tree) {
 171                 if(!e->reverse) {
 172                         continue;
 173                 }
 174
 175                 bool found = false;
 176
 177                 for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 178                         if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
 179                                 found = true;
 180                                 break;
 181                         }
 182                 }
 183
 184                 if(found) {
 185                         continue;
 186                 }
 187
 188                 // Create a new struct addrinfo, and put it at the head of the list.
 189                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(e->reverse->address.sa));
 190                 nai->ai_next = ai;
 191                 ai = nai;
 192
 193                 ai->ai_family = e->reverse->address.sa.sa_family;
 194                 ai->ai_socktype = SOCK_STREAM;
 195                 ai->ai_protocol = IPPROTO_TCP;
 196                 ai->ai_addrlen = SALEN(e->reverse->address.sa);
 197                 ai->ai_addr = (struct sockaddr *)(nai + 1);
 198                 memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
 199         }
 200
 201         return ai;
 202 }
 203
 204 // Build a list of recently seen addresses.
 205 static struct addrinfo *get_recent_addresses(node_t *n) {
 206         struct addrinfo *ai = NULL;
 207         struct addrinfo *aip;
 208
 209         for(int i = 0; i < 5; i++) {
 210                 if(!n->recent[i].sa.sa_family) {
 211                         break;
 212                 }
 213
 214                 // Create a new struct addrinfo, and put it at the end of the list.
 215                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(n->recent[i].sa));
 216
 217                 if(!ai) {
 218                         ai = nai;
 219                 } else {
 220                         aip->ai_next = nai;
 221                 }
 222
 223                 aip = nai;
 224
 225                 nai->ai_family = n->recent[i].sa.sa_family;
 226                 nai->ai_socktype = SOCK_STREAM;
 227                 nai->ai_protocol = IPPROTO_TCP;
 228                 nai->ai_addrlen = SALEN(n->recent[i].sa);
 229                 nai->ai_addr = (struct sockaddr *)(nai + 1);
 230                 memcpy(nai->ai_addr, &n->recent[i], nai->ai_addrlen);
 231         }
 232
 233         return ai;
 234 }
 235
 236 // Free struct addrinfo list from get_known_addresses().
 237 static void free_known_addresses(struct addrinfo *ai) {
 238         for(struct addrinfo *aip = ai, *next; aip; aip = next) {
 239                 next = aip->ai_next;
 240                 free(aip);
 241         }
 242 }
 243
 244 static void canonical_resolve_cb(meshlink_handle_t *mesh, char *host, char *serv, void *data, struct addrinfo *ai, int err) {
 245         (void)serv;
 246         (void)err;
 247         node_t *n = data;
 248
 249         free(host);
 250         free(serv);
 251
 252         for list_each(outgoing_t, outgoing, mesh->outgoings) {
 253                 if(outgoing->node == n) {
 254                         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 255                                 outgoing->ai = ai;
 256                                 outgoing->aip = NULL;
 257                                 outgoing->state = OUTGOING_CANONICAL;
 258                                 do_outgoing_connection(mesh, outgoing);
 259                         }
 260
 261                         return;
 262                 }
 263         }
 264 }
 265
 266 static bool get_next_outgoing_address(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 267         (void)mesh;
 268
 269         bool start = false;
 270
 271         if(outgoing->state == OUTGOING_START) {
 272                 start = true;
 273                 outgoing->state = OUTGOING_CANONICAL_RESOLVE;
 274         }
 275
 276         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 277                 node_t *n = outgoing->node;
 278
 279                 if(n->canonical_address) {
 280                         char *address = xstrdup(n->canonical_address);
 281                         char *port = strchr(address, ' ');
 282
 283                         if(port) {
 284                                 *port++ = 0;
 285                                 port = xstrdup(port);
 286                                 adns_queue(mesh, address, port, canonical_resolve_cb, outgoing->node, 2);
 287                                 return false;
 288                         } else {
 289                                 logger(mesh, MESHLINK_ERROR, "Canonical address for %s is missing port number", n->name);
 290                                 free(address);
 291                                 outgoing->state = OUTGOING_RECENT;
 292                         }
 293
 294                 } else {
 295                         outgoing->state = OUTGOING_RECENT;
 296                 }
 297         }
 298
 299         if(outgoing->state == OUTGOING_CANONICAL) {
 300                 if(!outgoing->aip) {
 301                         outgoing->aip = outgoing->ai;
 302                 } else {
 303                         outgoing->aip = outgoing->aip->ai_next;
 304                 }
 305
 306                 if(outgoing->aip) {
 307                         return true;
 308                 }
 309
 310                 if(outgoing->ai) {
 311                         freeaddrinfo(outgoing->ai);
 312                 }
 313
 314                 outgoing->ai = NULL;
 315                 outgoing->aip = NULL;
 316                 outgoing->state = OUTGOING_RECENT;
 317         }
 318
 319         if(outgoing->state == OUTGOING_RECENT) {
 320                 if(!outgoing->aip) {
 321                         outgoing->ai = get_recent_addresses(outgoing->node);
 322                         outgoing->aip = outgoing->ai;
 323                 } else {
 324                         outgoing->aip = outgoing->aip->ai_next;
 325                 }
 326
 327                 if(outgoing->aip) {
 328                         return true;
 329                 }
 330
 331                 free_known_addresses(outgoing->ai);
 332                 outgoing->ai = NULL;
 333                 outgoing->aip = NULL;
 334                 outgoing->state = OUTGOING_KNOWN;
 335         }
 336
 337         if(outgoing->state == OUTGOING_KNOWN) {
 338                 if(!outgoing->aip) {
 339                         outgoing->ai = get_known_addresses(outgoing->node);
 340                         outgoing->aip = outgoing->ai;
 341                 } else {
 342                         outgoing->aip = outgoing->aip->ai_next;
 343                 }
 344
 345                 if(outgoing->aip) {
 346                         return true;
 347                 }
 348
 349                 free_known_addresses(outgoing->ai);
 350                 outgoing->ai = NULL;
 351                 outgoing->aip = NULL;
 352                 outgoing->state = OUTGOING_END;
 353         }
 354
 355         if(start) {
 356                 outgoing->state = OUTGOING_NO_KNOWN_ADDRESSES;
 357         }
 358
 359         return false;
 360 }
 361
 362 void do_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 363 begin:
 364
 365         if(!get_next_outgoing_address(mesh, outgoing)) {
 366                 if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 367                         /* We are waiting for a callback from the ADNS thread */
 368                 } else if(outgoing->state == OUTGOING_NO_KNOWN_ADDRESSES) {
 369                         logger(mesh, MESHLINK_ERROR, "No known addresses for %s", outgoing->node->name);
 370                 } else {
 371                         logger(mesh, MESHLINK_ERROR, "Could not set up a meta connection to %s", outgoing->node->name);
 372                         retry_outgoing(mesh, outgoing);
 373                 }
 374
 375                 return;
 376         }
 377
 378         connection_t *c = new_connection();
 379         c->outgoing = outgoing;
 380
 381         memcpy(&c->address, outgoing->aip->ai_addr, outgoing->aip->ai_addrlen);
 382
 383         if(mesh->log_level <= MESHLINK_INFO) {
 384                 char *hostname = sockaddr2hostname(&c->address);
 385                 logger(mesh, MESHLINK_INFO, "Trying to connect to %s at %s", outgoing->node->name, hostname);
 386                 free(hostname);
 387         }
 388
 389         c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 390
 391         if(c->socket == -1) {
 392                 if(mesh->log_level <= MESHLINK_ERROR) {
 393                         char *hostname = sockaddr2hostname(&c->address);
 394                         logger(mesh, MESHLINK_ERROR, "Creating socket for %s at %s failed: %s", c->name, hostname, sockstrerror(sockerrno));
 395                         free(hostname);
 396                 }
 397
 398                 free_connection(c);
 399                 goto begin;
 400         }
 401
 402         configure_tcp(c);
 403
 404 #ifdef FD_CLOEXEC
 405         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
 406 #endif
 407
 408 #if defined(IPV6_V6ONLY)
 409
 410         if(c->address.sa.sa_family == AF_INET6) {
 411                 static const int option = 1;
 412                 setsockopt(c->socket, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
 413         }
 414
 415 #endif
 416
 417         /* Connect */
 418
 419         int result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
 420
 421         if(result == -1 && !sockinprogress(sockerrno)) {
 422                 if(mesh->log_level <= MESHLINK_ERROR) {
 423                         char *hostname = sockaddr2hostname(&c->address);
 424                         logger(mesh, MESHLINK_ERROR, "Could not connect to %s: %s", outgoing->node->name, sockstrerror(sockerrno));
 425                         free(hostname);
 426                 }
 427
 428                 free_connection(c);
 429                 goto begin;
 430         }
 431
 432         /* Now that there is a working socket, fill in the rest and register this connection. */
 433
 434         c->status.connecting = true;
 435         c->status.initiator = true;
 436         c->name = xstrdup(outgoing->node->name);
 437         c->last_ping_time = mesh->loop.now.tv_sec;
 438
 439         connection_add(mesh, c);
 440
 441         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ | IO_WRITE);
 442 }
 443
 444 void reset_outgoing(outgoing_t *outgoing) {
 445         if(outgoing->ai) {
 446                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 447                         free_known_addresses(outgoing->ai);
 448                 } else {
 449                         freeaddrinfo(outgoing->ai);
 450                 }
 451         }
 452
 453         outgoing->ai = NULL;
 454         outgoing->aip = NULL;
 455         outgoing->state = OUTGOING_START;
 456 }
 457
 458 void setup_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 459         timeout_del(&mesh->loop, &outgoing->ev);
 460
 461         if(outgoing->node->connection) {
 462                 logger(mesh, MESHLINK_INFO, "Already connected to %s", outgoing->node->name);
 463
 464                 outgoing->node->connection->outgoing = outgoing;
 465                 return;
 466         }
 467
 468         reset_outgoing(outgoing);
 469
 470         if(outgoing->node->status.blacklisted) {
 471                 return;
 472         }
 473
 474         if(mesh->connection_try_cb) {
 475                 mesh->connection_try_cb(mesh, (meshlink_node_t *)outgoing->node);
 476         }
 477
 478         do_outgoing_connection(mesh, outgoing);
 479 }
 480
 481 /// Delayed close of a filedescriptor.
 482 static void tarpit(meshlink_handle_t *mesh, int fd) {
 483         if(!fd) {
 484                 return;
 485         }
 486
 487         if(mesh->pits[mesh->next_pit]) {
 488                 closesocket(mesh->pits[mesh->next_pit]);
 489         }
 490
 491         mesh->pits[mesh->next_pit++] = fd;
 492
 493         if(mesh->next_pit >= (int)(sizeof mesh->pits / sizeof mesh->pits[0])) {
 494                 mesh->next_pit = 0;
 495         }
 496 }
 497
 498 /*
 499   accept a new tcp connect and create a
 500   new connection
 501 */
 502 void handle_new_meta_connection(event_loop_t *loop, void *data, int flags) {
 503         (void)flags;
 504         meshlink_handle_t *mesh = loop->data;
 505         listen_socket_t *l = data;
 506         connection_t *c;
 507         sockaddr_t sa;
 508         int fd;
 509         socklen_t len = sizeof(sa);
 510
 511         memset(&sa, 0, sizeof(sa));
 512
 513         fd = accept(l->tcp.fd, &sa.sa, &len);
 514
 515         if(fd < 0) {
 516                 if(errno == EINVAL) { // TODO: check if Windows agrees
 517                         event_loop_stop(loop);
 518                         return;
 519                 }
 520
 521                 logger(mesh, MESHLINK_ERROR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 522                 return;
 523         }
 524
 525         sockaddrunmap(&sa);
 526
 527         /* Rate limit incoming connections to max_connection_burst/second. */
 528
 529         if(mesh->loop.now.tv_sec != mesh->connection_burst_time) {
 530                 mesh->connection_burst_time = mesh->loop.now.tv_sec;
 531                 mesh->connection_burst = 0;
 532         }
 533
 534         if(mesh->connection_burst >= max_connection_burst) {
 535                 tarpit(mesh, fd);
 536                 return;
 537         }
 538
 539         mesh->connection_burst++;
 540
 541         // Accept the new connection
 542
 543         c = new_connection();
 544         c->name = xstrdup("<unknown>");
 545
 546         c->address = sa;
 547         c->socket = fd;
 548         c->last_ping_time = mesh->loop.now.tv_sec;
 549
 550         char *hostname = sockaddr2hostname(&sa);
 551         logger(mesh, MESHLINK_INFO, "Connection from %s", hostname);
 552         free(hostname);
 553
 554         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
 555
 556         configure_tcp(c);
 557
 558         connection_add(mesh, c);
 559
 560         c->allow_request = ID;
 561         send_id(mesh, c);
 562 }
 563
 564 static void free_outgoing(outgoing_t *outgoing) {
 565         meshlink_handle_t *mesh = outgoing->node->mesh;
 566
 567         timeout_del(&mesh->loop, &outgoing->ev);
 568
 569         if(outgoing->ai) {
 570                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 571                         free_known_addresses(outgoing->ai);
 572                 } else {
 573                         freeaddrinfo(outgoing->ai);
 574                 }
 575         }
 576
 577         free(outgoing);
 578 }
 579
 580 void init_outgoings(meshlink_handle_t *mesh) {
 581         mesh->outgoings = list_alloc((list_action_t)free_outgoing);
 582 }
 583
 584 void exit_outgoings(meshlink_handle_t *mesh) {
 585         if(mesh->outgoings) {
 586                 list_delete_list(mesh->outgoings);
 587                 mesh->outgoings = NULL;
 588         }
 589 }