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 "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 #if defined(SO_NOSIGPIPE)
  75         int nosigpipe = 1;
  76         setsockopt(c->socket, SOL_SOCKET, SO_NOSIGPIPE, (void *)&nosigpipe, sizeof(nosigpipe));
  77 #endif
  78 }
  79
  80 static void retry_outgoing_handler(event_loop_t *loop, void *data) {
  81         assert(data);
  82
  83         meshlink_handle_t *mesh = loop->data;
  84         outgoing_t *outgoing = data;
  85         setup_outgoing_connection(mesh, outgoing);
  86 }
  87
  88 void retry_outgoing(meshlink_handle_t *mesh, outgoing_t *outgoing) {
  89         if(!mesh->reachable && mesh->loop.now.tv_sec < mesh->last_unreachable + mesh->dev_class_traits[outgoing->node->devclass].fast_retry_period) {
  90                 outgoing->timeout = 1;
  91         } else {
  92                 outgoing->timeout += 5;
  93         }
  94
  95         int maxtimeout = mesh->dev_class_traits[outgoing->node->devclass].maxtimeout;
  96
  97         if(outgoing->timeout > maxtimeout) {
  98                 outgoing->timeout = maxtimeout;
  99         }
 100
 101         timeout_add(&mesh->loop, &outgoing->ev, retry_outgoing_handler, outgoing, &(struct timespec) {
 102                 outgoing->timeout, prng(mesh, TIMER_FUDGE)
 103         });
 104
 105         logger(mesh, MESHLINK_INFO, "Trying to re-establish outgoing connection in %d seconds", outgoing->timeout);
 106 }
 107
 108 void finish_connecting(meshlink_handle_t *mesh, connection_t *c) {
 109         logger(mesh, MESHLINK_INFO, "Connected to %s", c->name);
 110
 111         c->last_ping_time = mesh->loop.now.tv_sec;
 112         c->status.connecting = false;
 113
 114         send_id(mesh, c);
 115 }
 116
 117 static void handle_meta_write(meshlink_handle_t *mesh, connection_t *c) {
 118         if(c->outbuf.len <= c->outbuf.offset) {
 119                 return;
 120         }
 121
 122         ssize_t outlen = send(c->socket, c->outbuf.data + c->outbuf.offset, c->outbuf.len - c->outbuf.offset, MSG_NOSIGNAL);
 123
 124         if(outlen <= 0) {
 125                 if(!errno || errno == EPIPE) {
 126                         logger(mesh, MESHLINK_INFO, "Connection closed by %s", c->name);
 127                 } else if(sockwouldblock(sockerrno)) {
 128                         logger(mesh, MESHLINK_DEBUG, "Sending %lu bytes to %s would block", (unsigned long)(c->outbuf.len - c->outbuf.offset), c->name);
 129                         return;
 130                 } else {
 131                         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));
 132                 }
 133
 134                 terminate_connection(mesh, c, c->status.active);
 135                 return;
 136         }
 137
 138         buffer_read(&c->outbuf, outlen);
 139
 140         if(!c->outbuf.len) {
 141                 io_set(&mesh->loop, &c->io, IO_READ);
 142         }
 143 }
 144
 145 void flush_meta(meshlink_handle_t *mesh, connection_t *c) {
 146         handle_meta_write(mesh, c);
 147 }
 148
 149 static void handle_meta_io(event_loop_t *loop, void *data, int flags) {
 150         meshlink_handle_t *mesh = loop->data;
 151         connection_t *c = data;
 152
 153         if(c->status.connecting) {
 154                 c->status.connecting = false;
 155
 156                 int result;
 157                 socklen_t len = sizeof(result);
 158                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 159
 160                 if(!result) {
 161                         finish_connecting(mesh, c);
 162                 } else {
 163                         logger(mesh, MESHLINK_ERROR, "Error while connecting to %s: %s", c->name, sockstrerror(result));
 164                         terminate_connection(mesh, c, false);
 165                         return;
 166                 }
 167         }
 168
 169         if(flags & IO_WRITE) {
 170                 handle_meta_write(mesh, c);
 171         } else {
 172                 handle_meta_connection_data(mesh, c);
 173         }
 174 }
 175
 176 // Build a list of recently seen addresses.
 177 static struct addrinfo *get_recent_addresses(node_t *n) {
 178         struct addrinfo *ai = NULL;
 179         struct addrinfo *aip;
 180
 181         for(int i = 0; i < 5; i++) {
 182                 if(!n->recent[i].sa.sa_family) {
 183                         break;
 184                 }
 185
 186                 // Create a new struct addrinfo, and put it at the end of the list.
 187                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(n->recent[i].sa));
 188
 189                 if(!ai) {
 190                         ai = nai;
 191                 } else {
 192                         aip->ai_next = nai;
 193                 }
 194
 195                 aip = nai;
 196
 197                 nai->ai_family = n->recent[i].sa.sa_family;
 198                 nai->ai_socktype = SOCK_STREAM;
 199                 nai->ai_protocol = IPPROTO_TCP;
 200                 nai->ai_addrlen = SALEN(n->recent[i].sa);
 201                 nai->ai_addr = (struct sockaddr *)(nai + 1);
 202                 memcpy(nai->ai_addr, &n->recent[i], nai->ai_addrlen);
 203         }
 204
 205         return ai;
 206 }
 207
 208 // Free struct addrinfo list from get_known_addresses().
 209 static void free_known_addresses(struct addrinfo *ai) {
 210         for(struct addrinfo *aip = ai, *next; aip; aip = next) {
 211                 next = aip->ai_next;
 212                 free(aip);
 213         }
 214 }
 215
 216 static bool get_next_outgoing_address(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 217         (void)mesh;
 218
 219         bool start = false;
 220
 221         if(outgoing->state == OUTGOING_START) {
 222                 start = true;
 223                 outgoing->state = OUTGOING_CANONICAL_RESOLVE;
 224         }
 225
 226         if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 227                 node_t *n = outgoing->node;
 228
 229                 if(n->canonical_address) {
 230                         char *address = xstrdup(n->canonical_address);
 231                         char *port = strchr(address, ' ');
 232
 233                         if(port) {
 234                                 *port++ = 0;
 235                                 outgoing->ai = str2addrinfo(address, port, SOCK_STREAM);
 236                                 outgoing->aip = NULL;
 237                                 outgoing->state = OUTGOING_CANONICAL;
 238                         } else {
 239                                 logger(mesh, MESHLINK_ERROR, "Canonical address for %s is missing port number", n->name);
 240                                 outgoing->state = OUTGOING_RECENT;
 241                         }
 242
 243                         free(address);
 244                 } else {
 245                         outgoing->state = OUTGOING_RECENT;
 246                 }
 247         }
 248
 249         if(outgoing->state == OUTGOING_CANONICAL) {
 250                 if(!outgoing->aip) {
 251                         outgoing->aip = outgoing->ai;
 252                 } else {
 253                         outgoing->aip = outgoing->aip->ai_next;
 254                 }
 255
 256                 if(outgoing->aip) {
 257                         return true;
 258                 }
 259
 260                 if(outgoing->ai) {
 261                         freeaddrinfo(outgoing->ai);
 262                 }
 263
 264                 outgoing->ai = NULL;
 265                 outgoing->aip = NULL;
 266                 outgoing->state = OUTGOING_END;
 267         }
 268
 269         if(outgoing->state == OUTGOING_RECENT) {
 270                 if(!outgoing->aip) {
 271                         outgoing->ai = get_recent_addresses(outgoing->node);
 272                         outgoing->aip = outgoing->ai;
 273                 } else {
 274                         outgoing->aip = outgoing->aip->ai_next;
 275                 }
 276
 277                 if(outgoing->aip) {
 278                         return true;
 279                 }
 280
 281                 free_known_addresses(outgoing->ai);
 282                 outgoing->ai = NULL;
 283                 outgoing->aip = NULL;
 284                 outgoing->state = OUTGOING_END;
 285         }
 286
 287         if(start) {
 288                 outgoing->state = OUTGOING_NO_KNOWN_ADDRESSES;
 289         }
 290
 291         return false;
 292 }
 293
 294 void do_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 295 begin:
 296
 297         if(!get_next_outgoing_address(mesh, outgoing)) {
 298                 if(outgoing->state == OUTGOING_CANONICAL_RESOLVE) {
 299                         /* We are waiting for a callback from the ADNS thread */
 300                 } else if(outgoing->state == OUTGOING_NO_KNOWN_ADDRESSES) {
 301                         logger(mesh, MESHLINK_ERROR, "No known addresses for %s", outgoing->node->name);
 302                         list_delete(mesh->outgoings, outgoing);
 303                 } else {
 304                         logger(mesh, MESHLINK_ERROR, "Could not set up a meta connection to %s", outgoing->node->name);
 305                         retry_outgoing(mesh, outgoing);
 306                 }
 307
 308                 return;
 309         }
 310
 311         connection_t *c = new_connection();
 312         c->outgoing = outgoing;
 313
 314         memcpy(&c->address, outgoing->aip->ai_addr, outgoing->aip->ai_addrlen);
 315
 316         if(mesh->log_level <= MESHLINK_INFO) {
 317                 char *hostname = sockaddr2hostname(&c->address);
 318                 logger(mesh, MESHLINK_INFO, "Trying to connect to %s at %s", outgoing->node->name, hostname);
 319                 free(hostname);
 320         }
 321
 322         c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 323
 324         if(c->socket == -1) {
 325                 if(mesh->log_level <= MESHLINK_ERROR) {
 326                         char *hostname = sockaddr2hostname(&c->address);
 327                         logger(mesh, MESHLINK_ERROR, "Creating socket for %s at %s failed: %s", c->name, hostname, sockstrerror(sockerrno));
 328                         free(hostname);
 329                 }
 330
 331                 free_connection(c);
 332                 goto begin;
 333         }
 334
 335         configure_tcp(c);
 336
 337 #ifdef FD_CLOEXEC
 338         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
 339 #endif
 340
 341 #if defined(IPV6_V6ONLY)
 342
 343         if(c->address.sa.sa_family == AF_INET6) {
 344                 static const int option = 1;
 345                 setsockopt(c->socket, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
 346         }
 347
 348 #endif
 349
 350         /* Connect */
 351
 352         int result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
 353
 354         if(result == -1 && !sockinprogress(sockerrno)) {
 355                 if(mesh->log_level <= MESHLINK_ERROR) {
 356                         char *hostname = sockaddr2hostname(&c->address);
 357                         logger(mesh, MESHLINK_ERROR, "Could not connect to %s: %s", outgoing->node->name, sockstrerror(sockerrno));
 358                         free(hostname);
 359                 }
 360
 361                 free_connection(c);
 362                 goto begin;
 363         }
 364
 365         /* Now that there is a working socket, fill in the rest and register this connection. */
 366
 367         c->status.connecting = true;
 368         c->status.initiator = true;
 369         c->name = xstrdup(outgoing->node->name);
 370         c->last_ping_time = mesh->loop.now.tv_sec;
 371
 372         connection_add(mesh, c);
 373
 374         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ | IO_WRITE);
 375 }
 376
 377 void reset_outgoing(outgoing_t *outgoing) {
 378         if(outgoing->ai) {
 379                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 380                         free_known_addresses(outgoing->ai);
 381                 } else {
 382                         freeaddrinfo(outgoing->ai);
 383                 }
 384         }
 385
 386         outgoing->ai = NULL;
 387         outgoing->aip = NULL;
 388         outgoing->state = OUTGOING_START;
 389 }
 390
 391 void setup_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 392         timeout_del(&mesh->loop, &outgoing->ev);
 393
 394         if(outgoing->node->connection) {
 395                 logger(mesh, MESHLINK_INFO, "Already connected to %s", outgoing->node->name);
 396
 397                 outgoing->node->connection->outgoing = outgoing;
 398                 return;
 399         }
 400
 401         reset_outgoing(outgoing);
 402
 403         if(outgoing->node->status.blacklisted) {
 404                 return;
 405         }
 406
 407         if(mesh->connection_try_cb) {
 408                 mesh->connection_try_cb(mesh, (meshlink_node_t *)outgoing->node);
 409         }
 410
 411         do_outgoing_connection(mesh, outgoing);
 412 }
 413
 414 /// Delayed close of a filedescriptor.
 415 static void tarpit(meshlink_handle_t *mesh, int fd) {
 416         if(!fd) {
 417                 return;
 418         }
 419
 420         if(mesh->pits[mesh->next_pit]) {
 421                 closesocket(mesh->pits[mesh->next_pit]);
 422         }
 423
 424         mesh->pits[mesh->next_pit++] = fd;
 425
 426         if(mesh->next_pit >= (int)(sizeof mesh->pits / sizeof mesh->pits[0])) {
 427                 mesh->next_pit = 0;
 428         }
 429 }
 430
 431 /*
 432   accept a new tcp connect and create a
 433   new connection
 434 */
 435 void handle_new_meta_connection(event_loop_t *loop, void *data, int flags) {
 436         (void)flags;
 437         meshlink_handle_t *mesh = loop->data;
 438         listen_socket_t *l = data;
 439         connection_t *c;
 440         sockaddr_t sa;
 441         int fd;
 442         socklen_t len = sizeof(sa);
 443
 444         memset(&sa, 0, sizeof(sa));
 445
 446         fd = accept(l->tcp.fd, &sa.sa, &len);
 447
 448         if(fd < 0) {
 449                 if(sockwouldblock(errno)) {
 450                         return;
 451                 }
 452
 453                 if(errno == EINVAL) { // TODO: check if Windows agrees
 454                         event_loop_stop(loop);
 455                         return;
 456                 }
 457
 458                 logger(mesh, MESHLINK_ERROR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 459                 return;
 460         }
 461
 462         sockaddrunmap(&sa);
 463
 464         /* Rate limit incoming connections to max_connection_burst/second. */
 465
 466         if(mesh->loop.now.tv_sec != mesh->connection_burst_time) {
 467                 mesh->connection_burst_time = mesh->loop.now.tv_sec;
 468                 mesh->connection_burst = 0;
 469         }
 470
 471         if(mesh->connection_burst >= max_connection_burst) {
 472                 tarpit(mesh, fd);
 473                 return;
 474         }
 475
 476         mesh->connection_burst++;
 477
 478         // Accept the new connection
 479
 480         c = new_connection();
 481         c->name = xstrdup("<unknown>");
 482
 483         c->address = sa;
 484         c->socket = fd;
 485         c->last_ping_time = mesh->loop.now.tv_sec;
 486
 487         char *hostname = sockaddr2hostname(&sa);
 488         logger(mesh, MESHLINK_INFO, "Connection from %s", hostname);
 489         free(hostname);
 490
 491         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
 492
 493         configure_tcp(c);
 494
 495         connection_add(mesh, c);
 496
 497         c->allow_request = ID;
 498         send_id(mesh, c);
 499 }
 500
 501 static void free_outgoing(outgoing_t *outgoing) {
 502         meshlink_handle_t *mesh = outgoing->node->mesh;
 503
 504         timeout_del(&mesh->loop, &outgoing->ev);
 505
 506         if(outgoing->ai) {
 507                 if(outgoing->state == OUTGOING_RECENT || outgoing->state == OUTGOING_KNOWN) {
 508                         free_known_addresses(outgoing->ai);
 509                 } else {
 510                         freeaddrinfo(outgoing->ai);
 511                 }
 512         }
 513
 514         free(outgoing);
 515 }
 516
 517 void init_outgoings(meshlink_handle_t *mesh) {
 518         mesh->outgoings = list_alloc((list_action_t)free_outgoing);
 519 }
 520
 521 void exit_outgoings(meshlink_handle_t *mesh) {
 522         if(mesh->outgoings) {
 523                 list_delete_list(mesh->outgoings);
 524                 mesh->outgoings = NULL;
 525         }
 526 }