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 "conf.h"
  23 #include "connection.h"
  24 #include "list.h"
  25 #include "logger.h"
  26 #include "meshlink_internal.h"
  27 #include "meta.h"
  28 #include "net.h"
  29 #include "netutl.h"
  30 #include "protocol.h"
  31 #include "utils.h"
  32 #include "xalloc.h"
  33
  34 /* Needed on Mac OS/X */
  35 #ifndef SOL_TCP
  36 #define SOL_TCP IPPROTO_TCP
  37 #endif
  38
  39 #ifndef MSG_NOSIGNAL
  40 #define MSG_NOSIGNAL 0
  41 #endif
  42
  43 static const int max_connection_burst = 100;
  44
  45 /* Setup sockets */
  46
  47 static void configure_tcp(connection_t *c) {
  48 #ifdef O_NONBLOCK
  49         int flags = fcntl(c->socket, F_GETFL);
  50
  51         if(fcntl(c->socket, F_SETFL, flags | O_NONBLOCK) < 0) {
  52                 logger(c->mesh, MESHLINK_ERROR, "System call `%s' failed: %s", "fcntl", strerror(errno));
  53         }
  54
  55 #elif defined(WIN32)
  56         unsigned long arg = 1;
  57
  58         if(ioctlsocket(c->socket, FIONBIO, &arg) != 0) {
  59                 logger(c->mesh, MESHLINK_ERROR, "System call `%s' failed: %s", "ioctlsocket", sockstrerror(sockerrno));
  60         }
  61
  62 #endif
  63
  64 #if defined(SOL_TCP) && defined(TCP_NODELAY)
  65         int nodelay = 1;
  66         setsockopt(c->socket, SOL_TCP, TCP_NODELAY, (void *)&nodelay, sizeof(nodelay));
  67 #endif
  68
  69 #if defined(IP_TOS) && defined(IPTOS_LOWDELAY)
  70         int lowdelay = IPTOS_LOWDELAY;
  71         setsockopt(c->socket, IPPROTO_IP, IP_TOS, (void *)&lowdelay, sizeof(lowdelay));
  72 #endif
  73 }
  74
  75 static void retry_outgoing_handler(event_loop_t *loop, void *data) {
  76         assert(data);
  77
  78         meshlink_handle_t *mesh = loop->data;
  79         outgoing_t *outgoing = data;
  80         setup_outgoing_connection(mesh, outgoing);
  81 }
  82
  83 void retry_outgoing(meshlink_handle_t *mesh, outgoing_t *outgoing) {
  84         if(!mesh->reachable && mesh->loop.now.tv_sec < mesh->last_unreachable + mesh->dev_class_traits[mesh->devclass].fast_retry_period) {
  85                 outgoing->timeout = 1;
  86         } else {
  87                 outgoing->timeout += 5;
  88         }
  89
  90         if(outgoing->timeout > mesh->maxtimeout) {
  91                 outgoing->timeout = mesh->maxtimeout;
  92         }
  93
  94         timeout_add(&mesh->loop, &outgoing->ev, retry_outgoing_handler, outgoing, &(struct timespec) {
  95                 outgoing->timeout, prng(mesh, TIMER_FUDGE)
  96         });
  97
  98         logger(mesh, MESHLINK_INFO, "Trying to re-establish outgoing connection in %d seconds", outgoing->timeout);
  99 }
 100
 101 void finish_connecting(meshlink_handle_t *mesh, connection_t *c) {
 102         logger(mesh, MESHLINK_INFO, "Connected to %s", c->name);
 103
 104         c->last_ping_time = mesh->loop.now.tv_sec;
 105         c->status.connecting = false;
 106
 107         send_id(mesh, c);
 108 }
 109
 110 static void handle_meta_write(meshlink_handle_t *mesh, connection_t *c) {
 111         if(c->outbuf.len <= c->outbuf.offset) {
 112                 return;
 113         }
 114
 115         ssize_t outlen = send(c->socket, c->outbuf.data + c->outbuf.offset, c->outbuf.len - c->outbuf.offset, MSG_NOSIGNAL);
 116
 117         if(outlen <= 0) {
 118                 if(!errno || errno == EPIPE) {
 119                         logger(mesh, MESHLINK_INFO, "Connection closed by %s", c->name);
 120                 } else if(sockwouldblock(sockerrno)) {
 121                         logger(mesh, MESHLINK_DEBUG, "Sending %lu bytes to %s would block", (unsigned long)(c->outbuf.len - c->outbuf.offset), c->name);
 122                         return;
 123                 } else {
 124                         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));
 125                 }
 126
 127                 terminate_connection(mesh, c, c->status.active);
 128                 return;
 129         }
 130
 131         buffer_read(&c->outbuf, outlen);
 132
 133         if(!c->outbuf.len) {
 134                 io_set(&mesh->loop, &c->io, IO_READ);
 135         }
 136 }
 137
 138 static void handle_meta_io(event_loop_t *loop, void *data, int flags) {
 139         meshlink_handle_t *mesh = loop->data;
 140         connection_t *c = data;
 141
 142         if(c->status.connecting) {
 143                 c->status.connecting = false;
 144
 145                 int result;
 146                 socklen_t len = sizeof(result);
 147                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 148
 149                 if(!result) {
 150                         finish_connecting(mesh, c);
 151                 } else {
 152                         logger(mesh, MESHLINK_DEBUG, "Error while connecting to %s: %s", c->name, sockstrerror(result));
 153                         terminate_connection(mesh, c, false);
 154                         return;
 155                 }
 156         }
 157
 158         if(flags & IO_WRITE) {
 159                 handle_meta_write(mesh, c);
 160         } else {
 161                 handle_meta_connection_data(mesh, c);
 162         }
 163 }
 164
 165 // Find edges pointing to this node, and use them to build a list of unique, known addresses.
 166 static struct addrinfo *get_known_addresses(node_t *n) {
 167         struct addrinfo *ai = NULL;
 168
 169         for splay_each(edge_t, e, n->edge_tree) {
 170                 if(!e->reverse) {
 171                         continue;
 172                 }
 173
 174                 bool found = false;
 175
 176                 for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 177                         if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
 178                                 found = true;
 179                                 break;
 180                         }
 181                 }
 182
 183                 if(found) {
 184                         continue;
 185                 }
 186
 187                 // Create a new struct addrinfo, and put it at the head of the list.
 188                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(e->reverse->address.sa));
 189                 nai->ai_next = ai;
 190                 ai = nai;
 191
 192                 ai->ai_family = e->reverse->address.sa.sa_family;
 193                 ai->ai_socktype = SOCK_STREAM;
 194                 ai->ai_protocol = IPPROTO_TCP;
 195                 ai->ai_addrlen = SALEN(e->reverse->address.sa);
 196                 ai->ai_addr = (struct sockaddr *)(nai + 1);
 197                 memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
 198         }
 199
 200         return ai;
 201 }
 202
 203 // Build a list of recently seen addresses.
 204 static struct addrinfo *get_recent_addresses(node_t *n) {
 205         struct addrinfo *ai = NULL;
 206         struct addrinfo *aip;
 207
 208         for(int i = 0; i < 5; i++) {
 209                 if(!n->recent[i].sa.sa_family) {
 210                         break;
 211                 }
 212
 213                 // Create a new struct addrinfo, and put it at the end of the list.
 214                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(n->recent[i].sa));
 215
 216                 if(!ai) {
 217                         ai = nai;
 218                 } else {
 219                         aip->ai_next = nai;
 220                 }
 221
 222                 aip = nai;
 223
 224                 nai->ai_family = n->recent[i].sa.sa_family;
 225                 nai->ai_socktype = SOCK_STREAM;
 226                 nai->ai_protocol = IPPROTO_TCP;
 227                 nai->ai_addrlen = SALEN(n->recent[i].sa);
 228                 nai->ai_addr = (struct sockaddr *)(nai + 1);
 229                 memcpy(nai->ai_addr, &n->recent[i], nai->ai_addrlen);
 230         }
 231
 232         return ai;
 233 }
 234
 235 // Free struct addrinfo list from get_known_addresses().
 236 static void free_known_addresses(struct addrinfo *ai) {
 237         for(struct addrinfo *aip = ai, *next; aip; aip = next) {
 238                 next = aip->ai_next;
 239                 free(aip);
 240         }
 241 }
 242
 243 static struct addrinfo *get_canonical_address(node_t *n) {
 244         if(!n->canonical_address) {
 245                 return false;
 246         }
 247
 248         char *address = xstrdup(n->canonical_address);
 249         char *port = strchr(address, ' ');
 250
 251         if(!port) {
 252                 free(address);
 253                 return false;
 254         }
 255
 256         *port++ = 0;
 257
 258         struct addrinfo *ai = str2addrinfo(address, port, SOCK_STREAM);
 259         free(address);
 260
 261         return ai;
 262 }
 263
 264 static bool get_next_outgoing_address(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 265         (void)mesh;
 266
 267         bool start = false;
 268
 269         if(outgoing->state == OUTGOING_START) {
 270                 start = true;
 271                 outgoing->state = OUTGOING_CANONICAL;
 272         }
 273
 274         if(outgoing->state == OUTGOING_CANONICAL) {
 275                 if(!outgoing->aip) {
 276                         outgoing->ai = get_canonical_address(outgoing->node);
 277                         outgoing->aip = outgoing->ai;
 278                 } else {
 279                         outgoing->aip = outgoing->aip->ai_next;
 280                 }
 281
 282                 if(outgoing->aip) {
 283                         return true;
 284                 }
 285
 286                 freeaddrinfo(outgoing->ai);
 287                 outgoing->ai = NULL;
 288                 outgoing->aip = NULL;
 289                 outgoing->state = OUTGOING_RECENT;
 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_KNOWN;
 308         }
 309
 310         if(outgoing->state == OUTGOING_KNOWN) {
 311                 if(!outgoing->aip) {
 312                         outgoing->ai = get_known_addresses(outgoing->node);
 313                         outgoing->aip = outgoing->ai;
 314                 } else {
 315                         outgoing->aip = outgoing->aip->ai_next;
 316                 }
 317
 318                 if(outgoing->aip) {
 319                         return true;
 320                 }
 321
 322                 free_known_addresses(outgoing->ai);
 323                 outgoing->ai = NULL;
 324                 outgoing->aip = NULL;
 325                 outgoing->state = OUTGOING_END;
 326         }
 327
 328         if(start) {
 329                 outgoing->state = OUTGOING_NO_KNOWN_ADDRESSES;
 330         }
 331
 332         return false;
 333 }
 334
 335 void do_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 336 begin:
 337
 338         if(!get_next_outgoing_address(mesh, outgoing)) {
 339                 if(outgoing->state == OUTGOING_NO_KNOWN_ADDRESSES) {
 340                         logger(mesh, MESHLINK_ERROR, "No known addresses for %s", outgoing->node->name);
 341                 } else {
 342                         logger(mesh, MESHLINK_ERROR, "Could not set up a meta connection to %s", outgoing->node->name);
 343                         retry_outgoing(mesh, outgoing);
 344                 }
 345
 346                 return;
 347         }
 348
 349         connection_t *c = new_connection();
 350         c->outgoing = outgoing;
 351
 352         memcpy(&c->address, outgoing->aip->ai_addr, outgoing->aip->ai_addrlen);
 353
 354         if(mesh->log_level <= MESHLINK_INFO) {
 355                 char *hostname = sockaddr2hostname(&c->address);
 356                 logger(mesh, MESHLINK_INFO, "Trying to connect to %s at %s", outgoing->node->name, hostname);
 357                 free(hostname);
 358         }
 359
 360         c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 361
 362         if(c->socket == -1) {
 363                 if(mesh->log_level <= MESHLINK_ERROR) {
 364                         char *hostname = sockaddr2hostname(&c->address);
 365                         logger(mesh, MESHLINK_ERROR, "Creating socket for %s at %s failed: %s", c->name, hostname, sockstrerror(sockerrno));
 366                         free(hostname);
 367                 }
 368
 369                 free_connection(c);
 370                 goto begin;
 371         }
 372
 373         configure_tcp(c);
 374
 375 #ifdef FD_CLOEXEC
 376         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
 377 #endif
 378
 379 #if defined(IPV6_V6ONLY)
 380
 381         if(c->address.sa.sa_family == AF_INET6) {
 382                 static const int option = 1;
 383                 setsockopt(c->socket, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
 384         }
 385
 386 #endif
 387
 388         /* Connect */
 389
 390         int result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
 391
 392         if(result == -1 && !sockinprogress(sockerrno)) {
 393                 if(mesh->log_level <= MESHLINK_ERROR) {
 394                         char *hostname = sockaddr2hostname(&c->address);
 395                         logger(mesh, MESHLINK_ERROR, "Could not connect to %s: %s", outgoing->node->name, sockstrerror(sockerrno));
 396                         free(hostname);
 397                 }
 398
 399                 free_connection(c);
 400                 goto begin;
 401         }
 402
 403         /* Now that there is a working socket, fill in the rest and register this connection. */
 404
 405         c->status.connecting = true;
 406         c->status.initiator = true;
 407         c->name = xstrdup(outgoing->node->name);
 408         c->last_ping_time = mesh->loop.now.tv_sec;
 409
 410         connection_add(mesh, c);
 411
 412         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ | IO_WRITE);
 413 }
 414
 415 void reset_outgoing(outgoing_t *outgoing) {
 416         if(outgoing->ai) {
 417                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 418                         free_known_addresses(outgoing->ai);
 419                 } else {
 420                         freeaddrinfo(outgoing->ai);
 421                 }
 422         }
 423
 424         outgoing->ai = NULL;
 425         outgoing->aip = NULL;
 426         outgoing->state = OUTGOING_START;
 427 }
 428
 429 void setup_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 430         timeout_del(&mesh->loop, &outgoing->ev);
 431
 432         if(outgoing->node->connection) {
 433                 logger(mesh, MESHLINK_INFO, "Already connected to %s", outgoing->node->name);
 434
 435                 outgoing->node->connection->outgoing = outgoing;
 436                 return;
 437         }
 438
 439         reset_outgoing(outgoing);
 440
 441         if(outgoing->node->status.blacklisted) {
 442                 return;
 443         }
 444
 445         if(mesh->connection_try_cb) {
 446                 mesh->connection_try_cb(mesh, (meshlink_node_t *)outgoing->node);
 447         }
 448
 449         do_outgoing_connection(mesh, outgoing);
 450 }
 451
 452 /// Delayed close of a filedescriptor.
 453 static void tarpit(meshlink_handle_t *mesh, int fd) {
 454         if(!fd) {
 455                 return;
 456         }
 457
 458         if(mesh->pits[mesh->next_pit]) {
 459                 closesocket(mesh->pits[mesh->next_pit]);
 460         }
 461
 462         mesh->pits[mesh->next_pit++] = fd;
 463
 464         if(mesh->next_pit >= (int)(sizeof mesh->pits / sizeof mesh->pits[0])) {
 465                 mesh->next_pit = 0;
 466         }
 467 }
 468
 469 /*
 470   accept a new tcp connect and create a
 471   new connection
 472 */
 473 void handle_new_meta_connection(event_loop_t *loop, void *data, int flags) {
 474         (void)flags;
 475         meshlink_handle_t *mesh = loop->data;
 476         listen_socket_t *l = data;
 477         connection_t *c;
 478         sockaddr_t sa;
 479         int fd;
 480         socklen_t len = sizeof(sa);
 481
 482         memset(&sa, 0, sizeof(sa));
 483
 484         fd = accept(l->tcp.fd, &sa.sa, &len);
 485
 486         if(fd < 0) {
 487                 if(errno == EINVAL) { // TODO: check if Windows agrees
 488                         event_loop_stop(loop);
 489                         return;
 490                 }
 491
 492                 logger(mesh, MESHLINK_ERROR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 493                 return;
 494         }
 495
 496         sockaddrunmap(&sa);
 497
 498         /* Rate limit incoming connections to max_connection_burst/second. */
 499
 500         if(mesh->loop.now.tv_sec != mesh->connection_burst_time) {
 501                 mesh->connection_burst_time = mesh->loop.now.tv_sec;
 502                 mesh->connection_burst = 0;
 503         }
 504
 505         if(mesh->connection_burst >= max_connection_burst) {
 506                 tarpit(mesh, fd);
 507                 return;
 508         }
 509
 510         mesh->connection_burst++;
 511
 512         // Accept the new connection
 513
 514         c = new_connection();
 515         c->name = xstrdup("<unknown>");
 516
 517         c->address = sa;
 518         c->socket = fd;
 519         c->last_ping_time = mesh->loop.now.tv_sec;
 520
 521         char *hostname = sockaddr2hostname(&sa);
 522         logger(mesh, MESHLINK_INFO, "Connection from %s", hostname);
 523         free(hostname);
 524
 525         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
 526
 527         configure_tcp(c);
 528
 529         connection_add(mesh, c);
 530
 531         c->allow_request = ID;
 532         send_id(mesh, c);
 533 }
 534
 535 static void free_outgoing(outgoing_t *outgoing) {
 536         meshlink_handle_t *mesh = outgoing->node->mesh;
 537
 538         timeout_del(&mesh->loop, &outgoing->ev);
 539
 540         if(outgoing->ai) {
 541                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 542                         free_known_addresses(outgoing->ai);
 543                 } else {
 544                         freeaddrinfo(outgoing->ai);
 545                 }
 546         }
 547
 548         free(outgoing);
 549 }
 550
 551 void init_outgoings(meshlink_handle_t *mesh) {
 552         mesh->outgoings = list_alloc((list_action_t)free_outgoing);
 553 }
 554
 555 void exit_outgoings(meshlink_handle_t *mesh) {
 556         if(mesh->outgoings) {
 557                 list_delete_list(mesh->outgoings);
 558                 mesh->outgoings = NULL;
 559         }
 560 }