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