git.meshlink.io Git - meshlink/blob - src/net_socket.c

   1 /*
   2     net_socket.c -- Handle various kinds of sockets.
   3     Copyright (C) 2014 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 int addressfamily = AF_UNSPEC;
  40 int seconds_till_retry = 5;
  41 int max_connection_burst = 100;
  42
  43 /* Setup sockets */
  44
  45 static void configure_tcp(connection_t *c) {
  46 #ifdef O_NONBLOCK
  47         int flags = fcntl(c->socket, F_GETFL);
  48
  49         if(fcntl(c->socket, F_SETFL, flags | O_NONBLOCK) < 0) {
  50                 logger(DEBUG_ALWAYS, LOG_ERR, "fcntl for %s: %s", c->hostname, strerror(errno));
  51         }
  52 #elif defined(WIN32)
  53         unsigned long arg = 1;
  54
  55         if(ioctlsocket(c->socket, FIONBIO, &arg) != 0) {
  56                 logger(DEBUG_ALWAYS, LOG_ERR, "ioctlsocket for %s: %s", c->hostname, sockstrerror(sockerrno));
  57         }
  58 #endif
  59
  60 #if defined(SOL_TCP) && defined(TCP_NODELAY)
  61         option = 1;
  62         setsockopt(c->socket, SOL_TCP, TCP_NODELAY, (void *)&option, sizeof option);
  63 #endif
  64
  65 #if defined(SOL_IP) && defined(IP_TOS) && defined(IPTOS_LOWDELAY)
  66         option = IPTOS_LOWDELAY;
  67         setsockopt(c->socket, SOL_IP, IP_TOS, (void *)&option, sizeof option);
  68 #endif
  69 }
  70
  71 static bool bind_to_address(meshlink_handle_t *mesh, connection_t *c) {
  72         int s = -1;
  73
  74         for(int i = 0; i < mesh->listen_sockets && mesh->listen_socket[i].bindto; i++) {
  75                 if(mesh->listen_socket[i].sa.sa.sa_family != c->address.sa.sa_family)
  76                         continue;
  77                 if(s >= 0)
  78                         return false;
  79                 s = i;
  80         }
  81
  82         if(s < 0)
  83                 return false;
  84
  85         sockaddr_t sa = mesh->listen_socket[s].sa;
  86         if(sa.sa.sa_family == AF_INET)
  87                 sa.in.sin_port = 0;
  88         else if(sa.sa.sa_family == AF_INET6)
  89                 sa.in6.sin6_port = 0;
  90
  91         if(bind(c->socket, &sa.sa, SALEN(sa.sa))) {
  92                 logger(DEBUG_CONNECTIONS, LOG_WARNING, "Can't bind outgoing socket: %s", strerror(errno));
  93                 return false;
  94         }
  95
  96         return true;
  97 }
  98
  99 int setup_listen_socket(const sockaddr_t *sa) {
 100         int nfd;
 101         char *addrstr;
 102         int option;
 103
 104         nfd = socket(sa->sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 105
 106         if(nfd < 0) {
 107                 logger(DEBUG_STATUS, LOG_ERR, "Creating metasocket failed: %s", sockstrerror(sockerrno));
 108                 return -1;
 109         }
 110
 111 #ifdef FD_CLOEXEC
 112         fcntl(nfd, F_SETFD, FD_CLOEXEC);
 113 #endif
 114
 115         /* Optimize TCP settings */
 116
 117         option = 1;
 118         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof option);
 119
 120 #if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
 121         if(sa->sa.sa_family == AF_INET6)
 122                 setsockopt(nfd, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 123 #endif
 124
 125         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
 126                 closesocket(nfd);
 127                 addrstr = sockaddr2hostname(sa);
 128                 logger(DEBUG_ALWAYS, LOG_ERR, "Can't bind to %s/tcp: %s", addrstr, sockstrerror(sockerrno));
 129                 free(addrstr);
 130                 return -1;
 131         }
 132
 133         if(listen(nfd, 3)) {
 134                 closesocket(nfd);
 135                 logger(DEBUG_ALWAYS, LOG_ERR, "System call `%s' failed: %s", "listen", sockstrerror(sockerrno));
 136                 return -1;
 137         }
 138
 139         return nfd;
 140 }
 141
 142 int setup_vpn_in_socket(meshlink_handle_t *mesh, const sockaddr_t *sa) {
 143         int nfd;
 144         char *addrstr;
 145         int option;
 146
 147         nfd = socket(sa->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
 148
 149         if(nfd < 0) {
 150                 logger(DEBUG_ALWAYS, LOG_ERR, "Creating UDP socket failed: %s", sockstrerror(sockerrno));
 151                 return -1;
 152         }
 153
 154 #ifdef FD_CLOEXEC
 155         fcntl(nfd, F_SETFD, FD_CLOEXEC);
 156 #endif
 157
 158 #ifdef O_NONBLOCK
 159         {
 160                 int flags = fcntl(nfd, F_GETFL);
 161
 162                 if(fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0) {
 163                         closesocket(nfd);
 164                         logger(DEBUG_ALWAYS, LOG_ERR, "System call `%s' failed: %s", "fcntl",
 165                                    strerror(errno));
 166                         return -1;
 167                 }
 168         }
 169 #elif defined(WIN32)
 170         {
 171                 unsigned long arg = 1;
 172                 if(ioctlsocket(nfd, FIONBIO, &arg) != 0) {
 173                         closesocket(nfd);
 174                         logger(DEBUG_ALWAYS, LOG_ERR, "Call to `%s' failed: %s", "ioctlsocket", sockstrerror(sockerrno));
 175                         return -1;
 176                 }
 177         }
 178 #endif
 179
 180         option = 1;
 181         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof option);
 182         setsockopt(nfd, SOL_SOCKET, SO_BROADCAST, (void *)&option, sizeof option);
 183
 184 #if defined(IPPROTO_IPV6) && defined(IPV6_V6ONLY)
 185         if(sa->sa.sa_family == AF_INET6)
 186                 setsockopt(nfd, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 187 #endif
 188
 189 #if defined(IP_DONTFRAG) && !defined(IP_DONTFRAGMENT)
 190 #define IP_DONTFRAGMENT IP_DONTFRAG
 191 #endif
 192
 193 #if defined(SOL_IP) && defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DO)
 194         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 195                 option = IP_PMTUDISC_DO;
 196                 setsockopt(nfd, SOL_IP, IP_MTU_DISCOVER, (void *)&option, sizeof(option));
 197         }
 198 #elif defined(IPPROTO_IP) && defined(IP_DONTFRAGMENT)
 199         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 200                 option = 1;
 201                 setsockopt(nfd, IPPROTO_IP, IP_DONTFRAGMENT, (void *)&option, sizeof(option));
 202         }
 203 #else
 204 #warning No way to disable IPv4 fragmentation
 205 #endif
 206
 207 #if defined(SOL_IPV6) && defined(IPV6_MTU_DISCOVER) && defined(IPV6_PMTUDISC_DO)
 208         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 209                 option = IPV6_PMTUDISC_DO;
 210                 setsockopt(nfd, SOL_IPV6, IPV6_MTU_DISCOVER, (void *)&option, sizeof(option));
 211         }
 212 #elif defined(IPPROTO_IPV6) && defined(IPV6_DONTFRAG)
 213         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 214                 option = 1;
 215                 setsockopt(nfd, IPPROTO_IPV6, IPV6_DONTFRAG, (void *)&option, sizeof(option));
 216         }
 217 #else
 218 #warning No way to disable IPv6 fragmentation
 219 #endif
 220
 221         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
 222                 closesocket(nfd);
 223                 addrstr = sockaddr2hostname(sa);
 224                 logger(DEBUG_ALWAYS, LOG_ERR, "Can't bind to %s/udp: %s", addrstr, sockstrerror(sockerrno));
 225                 free(addrstr);
 226                 return -1;
 227         }
 228
 229         return nfd;
 230 } /* int setup_vpn_in_socket */
 231
 232 static void retry_outgoing_handler(event_loop_t *loop, void *data) {
 233         meshlink_handle_t *mesh = loop->data;
 234         outgoing_t *outgoing = data;
 235         setup_outgoing_connection(mesh, outgoing);
 236 }
 237
 238 void retry_outgoing(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 239         outgoing->timeout += 5;
 240
 241         if(outgoing->timeout > mesh->maxtimeout)
 242                 outgoing->timeout = mesh->maxtimeout;
 243
 244         timeout_add(&mesh->loop, &outgoing->ev, retry_outgoing_handler, outgoing, &(struct timeval){outgoing->timeout, rand() % 100000});
 245
 246         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Trying to re-establish outgoing connection in %d seconds", outgoing->timeout);
 247 }
 248
 249 void finish_connecting(meshlink_handle_t *mesh, connection_t *c) {
 250         logger(DEBUG_CONNECTIONS, LOG_INFO, "Connected to %s (%s)", c->name, c->hostname);
 251
 252         c->last_ping_time = mesh->loop.now.tv_sec;
 253         c->status.connecting = false;
 254
 255         send_id(mesh, c);
 256 }
 257
 258 static void do_outgoing_pipe(meshlink_handle_t *mesh, connection_t *c, char *command) {
 259 #ifndef HAVE_MINGW
 260         int fd[2];
 261
 262         if(socketpair(AF_UNIX, SOCK_STREAM, 0, fd)) {
 263                 logger(DEBUG_ALWAYS, LOG_ERR, "Could not create socketpair: %s", strerror(errno));
 264                 return;
 265         }
 266
 267         if(fork()) {
 268                 c->socket = fd[0];
 269                 close(fd[1]);
 270                 logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Using proxy %s", command);
 271                 return;
 272         }
 273
 274         close(0);
 275         close(1);
 276         close(fd[0]);
 277         dup2(fd[1], 0);
 278         dup2(fd[1], 1);
 279         close(fd[1]);
 280
 281         // Other filedescriptors should be closed automatically by CLOEXEC
 282
 283         char *host = NULL;
 284         char *port = NULL;
 285
 286         sockaddr2str(&c->address, &host, &port);
 287         setenv("REMOTEADDRESS", host, true);
 288         setenv("REMOTEPORT", port, true);
 289         setenv("NODE", c->name, true);
 290         setenv("NAME", mesh->self->name, true);
 291
 292         int result = system(command);
 293         if(result < 0)
 294                 logger(DEBUG_ALWAYS, LOG_ERR, "Could not execute %s: %s", command, strerror(errno));
 295         else if(result)
 296                 logger(DEBUG_ALWAYS, LOG_ERR, "%s exited with non-zero status %d", command, result);
 297         exit(result);
 298 #else
 299         logger(DEBUG_ALWAYS, LOG_ERR, "Proxy type exec not supported on this platform!");
 300         return;
 301 #endif
 302 }
 303
 304 static void handle_meta_write(meshlink_handle_t *mesh, connection_t *c) {
 305         if(c->outbuf.len <= c->outbuf.offset)
 306                 return;
 307
 308         ssize_t outlen = send(c->socket, c->outbuf.data + c->outbuf.offset, c->outbuf.len - c->outbuf.offset, 0);
 309         if(outlen <= 0) {
 310                 if(!errno || errno == EPIPE) {
 311                         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Connection closed by %s (%s)", c->name, c->hostname);
 312                 } else if(sockwouldblock(sockerrno)) {
 313                         logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Sending %d bytes to %s (%s) would block", c->outbuf.len - c->outbuf.offset, c->name, c->hostname);
 314                         return;
 315                 } else {
 316                         logger(DEBUG_CONNECTIONS, LOG_ERR, "Could not send %d bytes of data to %s (%s): %s", c->outbuf.len - c->outbuf.offset, c->name, c->hostname, strerror(errno));
 317                 }
 318
 319                 terminate_connection(mesh, c, c->status.active);
 320                 return;
 321         }
 322
 323         buffer_read(&c->outbuf, outlen);
 324         if(!c->outbuf.len)
 325                 io_set(&mesh->loop, &c->io, IO_READ);
 326 }
 327
 328 static void handle_meta_io(event_loop_t *loop, void *data, int flags) {
 329         meshlink_handle_t *mesh = loop->data;
 330         connection_t *c = data;
 331
 332         if(c->status.connecting) {
 333                 c->status.connecting = false;
 334
 335                 int result;
 336                 socklen_t len = sizeof result;
 337                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 338
 339                 if(!result)
 340                         finish_connecting(mesh, c);
 341                 else {
 342                         logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Error while connecting to %s (%s): %s", c->name, c->hostname, sockstrerror(result));
 343                         terminate_connection(mesh, c, false);
 344                         return;
 345                 }
 346         }
 347
 348         if(flags & IO_WRITE)
 349                 handle_meta_write(mesh, c);
 350         else
 351                 handle_meta_connection_data(mesh, c);
 352 }
 353
 354 bool do_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 355         char *address, *port, *space;
 356         struct addrinfo *proxyai = NULL;
 357         int result;
 358
 359 begin:
 360         if(!outgoing->ai) {
 361                 if(!outgoing->cfg) {
 362                         logger(DEBUG_CONNECTIONS, LOG_ERR, "Could not set up a meta connection to %s", outgoing->name);
 363                         retry_outgoing(mesh, outgoing);
 364                         return false;
 365                 }
 366
 367                 get_config_string(outgoing->cfg, &address);
 368
 369                 space = strchr(address, ' ');
 370                 if(space) {
 371                         port = xstrdup(space + 1);
 372                         *space = 0;
 373                 } else {
 374                         // TODO: Only allow Address statements?
 375                         if(!get_config_string(lookup_config(outgoing->config_tree, "Port"), &port))
 376                                 port = xstrdup("655");
 377                 }
 378
 379                 outgoing->ai = str2addrinfo(address, port, SOCK_STREAM);
 380                 free(address);
 381                 free(port);
 382
 383                 outgoing->aip = outgoing->ai;
 384                 outgoing->cfg = lookup_config_next(outgoing->config_tree, outgoing->cfg);
 385         }
 386
 387         if(!outgoing->aip) {
 388                 if(outgoing->ai)
 389                         freeaddrinfo(outgoing->ai);
 390                 outgoing->ai = NULL;
 391                 goto begin;
 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         outgoing->aip = outgoing->aip->ai_next;
 399
 400         c->hostname = sockaddr2hostname(&c->address);
 401
 402         logger(DEBUG_CONNECTIONS, LOG_INFO, "Trying to connect to %s (%s)", outgoing->name, c->hostname);
 403
 404         if(!mesh->proxytype) {
 405                 c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 406                 configure_tcp(c);
 407         } else if(mesh->proxytype == PROXY_EXEC) {
 408                 do_outgoing_pipe(mesh, c, mesh->proxyhost);
 409         } else {
 410                 proxyai = str2addrinfo(mesh->proxyhost, mesh->proxyport, SOCK_STREAM);
 411                 if(!proxyai) {
 412                         free_connection(c);
 413                         goto begin;
 414                 }
 415                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Using proxy at %s port %s", mesh->proxyhost, mesh->proxyport);
 416                 c->socket = socket(proxyai->ai_family, SOCK_STREAM, IPPROTO_TCP);
 417                 configure_tcp(c);
 418         }
 419
 420         if(c->socket == -1) {
 421                 logger(DEBUG_CONNECTIONS, LOG_ERR, "Creating socket for %s failed: %s", c->hostname, sockstrerror(sockerrno));
 422                 free_connection(c);
 423                 goto begin;
 424         }
 425
 426 #ifdef FD_CLOEXEC
 427         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
 428 #endif
 429
 430         if(mesh->proxytype != PROXY_EXEC) {
 431 #if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
 432                 int option = 1;
 433                 if(c->address.sa.sa_family == AF_INET6)
 434                         setsockopt(c->socket, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 435 #endif
 436
 437                 bind_to_address(mesh, c);
 438         }
 439
 440         /* Connect */
 441
 442         if(!mesh->proxytype) {
 443                 result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
 444         } else if(mesh->proxytype == PROXY_EXEC) {
 445                 result = 0;
 446         } else {
 447                 result = connect(c->socket, proxyai->ai_addr, proxyai->ai_addrlen);
 448                 freeaddrinfo(proxyai);
 449         }
 450
 451         if(result == -1 && !sockinprogress(sockerrno)) {
 452                 logger(DEBUG_CONNECTIONS, LOG_ERR, "Could not connect to %s (%s): %s", outgoing->name, c->hostname, sockstrerror(sockerrno));
 453                 free_connection(c);
 454
 455                 goto begin;
 456         }
 457
 458         /* Now that there is a working socket, fill in the rest and register this connection. */
 459
 460         c->status.connecting = true;
 461         c->name = xstrdup(outgoing->name);
 462         c->outcompression = mesh->self->connection->outcompression;
 463         c->last_ping_time = mesh->loop.now.tv_sec;
 464
 465         connection_add(mesh, c);
 466
 467         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ|IO_WRITE);
 468
 469         return true;
 470 }
 471
 472 // Find edges pointing to this node, and use them to build a list of unique, known addresses.
 473 static struct addrinfo *get_known_addresses(node_t *n) {
 474         struct addrinfo *ai = NULL;
 475
 476         for splay_each(edge_t, e, n->edge_tree) {
 477                 if(!e->reverse)
 478                         continue;
 479
 480                 bool found = false;
 481                 for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 482                         if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
 483                                 found = true;
 484                                 break;
 485                         }
 486                 }
 487                 if(found)
 488                         continue;
 489
 490                 struct addrinfo *nai = xzalloc(sizeof *nai);
 491                 if(ai)
 492                         ai->ai_next = nai;
 493                 ai = nai;
 494                 ai->ai_family = e->reverse->address.sa.sa_family;
 495                 ai->ai_socktype = SOCK_STREAM;
 496                 ai->ai_protocol = IPPROTO_TCP;
 497                 ai->ai_addrlen = SALEN(e->reverse->address.sa);
 498                 ai->ai_addr = xmalloc(ai->ai_addrlen);
 499                 memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
 500         }
 501
 502         return ai;
 503 }
 504
 505 void setup_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 506         bool blacklisted = false;
 507         timeout_del(&mesh->loop, &outgoing->ev);
 508
 509         node_t *n = lookup_node(mesh, outgoing->name);
 510
 511         if(n && n->connection) {
 512                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Already connected to %s", outgoing->name);
 513
 514                 n->connection->outgoing = outgoing;
 515                 return;
 516         }
 517
 518         init_configuration(&outgoing->config_tree);
 519         read_host_config(mesh, outgoing->config_tree, outgoing->name);
 520         outgoing->cfg = lookup_config(outgoing->config_tree, "Address");
 521
 522         get_config_bool(lookup_config(outgoing->config_tree, "blacklisted"), &blacklisted);
 523         if (blacklisted) return;
 524
 525         if(!outgoing->cfg) {
 526                 if(n)
 527                         outgoing->aip = outgoing->ai = get_known_addresses(n);
 528                 if(!outgoing->ai) {
 529                         logger(DEBUG_ALWAYS, LOG_ERR, "No address known for %s", outgoing->name);
 530                         return;
 531                 }
 532         }
 533
 534         do_outgoing_connection(mesh, outgoing);
 535 }
 536
 537 /*
 538   accept a new tcp connect and create a
 539   new connection
 540 */
 541 void handle_new_meta_connection(event_loop_t *loop, void *data, int flags) {
 542         meshlink_handle_t *mesh = loop->data;
 543         listen_socket_t *l = data;
 544         connection_t *c;
 545         sockaddr_t sa;
 546         int fd;
 547         socklen_t len = sizeof sa;
 548
 549         fd = accept(l->tcp.fd, &sa.sa, &len);
 550
 551         if(fd < 0) {
 552                 if(errno == EINVAL) { // TODO: check if Windows agrees
 553                         event_loop_stop(loop);
 554                         return;
 555                 }
 556
 557                 logger(DEBUG_ALWAYS, LOG_ERR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 558                 return;
 559         }
 560
 561         sockaddrunmap(&sa);
 562
 563         // Check if we get many connections from the same host
 564
 565         static sockaddr_t prev_sa;
 566         static int tarpit = -1;
 567
 568         if(tarpit >= 0) {
 569                 closesocket(tarpit);
 570                 tarpit = -1;
 571         }
 572
 573         if(!sockaddrcmp_noport(&sa, &prev_sa)) {
 574                 static int samehost_burst;
 575                 static int samehost_burst_time;
 576
 577                 if(mesh->loop.now.tv_sec - samehost_burst_time > samehost_burst)
 578                         samehost_burst = 0;
 579                 else
 580                         samehost_burst -= mesh->loop.now.tv_sec - samehost_burst_time;
 581
 582                 samehost_burst_time = mesh->loop.now.tv_sec;
 583                 samehost_burst++;
 584
 585                 if(samehost_burst > max_connection_burst) {
 586                         tarpit = fd;
 587                         return;
 588                 }
 589         }
 590
 591         memcpy(&prev_sa, &sa, sizeof sa);
 592
 593         // Check if we get many connections from different hosts
 594
 595         static int connection_burst;
 596         static int connection_burst_time;
 597
 598         if(mesh->loop.now.tv_sec - connection_burst_time > connection_burst)
 599                 connection_burst = 0;
 600         else
 601                 connection_burst -= mesh->loop.now.tv_sec - connection_burst_time;
 602
 603         connection_burst_time = mesh->loop.now.tv_sec;
 604         connection_burst++;
 605
 606         if(connection_burst >= max_connection_burst) {
 607                 connection_burst = max_connection_burst;
 608                 tarpit = fd;
 609                 return;
 610         }
 611
 612         // Accept the new connection
 613
 614         c = new_connection();
 615         c->name = xstrdup("<unknown>");
 616         c->outcompression = mesh->self->connection->outcompression;
 617
 618         c->address = sa;
 619         c->hostname = sockaddr2hostname(&sa);
 620         c->socket = fd;
 621         c->last_ping_time = mesh->loop.now.tv_sec;
 622
 623         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Connection from %s", c->hostname);
 624
 625         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
 626
 627         configure_tcp(c);
 628
 629         connection_add(mesh, c);
 630
 631         c->allow_request = ID;
 632         send_id(mesh, c);
 633 }
 634
 635 static void free_outgoing(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 636         timeout_del(&mesh->loop, &outgoing->ev);
 637
 638         if(outgoing->ai)
 639                 freeaddrinfo(outgoing->ai);
 640
 641         if(outgoing->config_tree)
 642                 exit_configuration(&outgoing->config_tree);
 643
 644         if(outgoing->name)
 645                 free(outgoing->name);
 646
 647         free(outgoing);
 648 }
 649
 650 void try_outgoing_connections(meshlink_handle_t *mesh) {
 651         /* If there is no outgoing list yet, create one. Otherwise, mark all outgoings as deleted. */
 652
 653         if(!mesh->outgoings) {
 654                 mesh->outgoings = list_alloc((list_action_t)free_outgoing);
 655         } else {
 656                 for list_each(outgoing_t, outgoing, mesh->outgoings)
 657                         outgoing->timeout = -1;
 658         }
 659
 660         /* Make sure there is one outgoing_t in the list for each ConnectTo. */
 661
 662         // TODO: Drop support for ConnectTo since AutoConnect is now always on?
 663         for(config_t *cfg = lookup_config(mesh->config, "ConnectTo"); cfg; cfg = lookup_config_next(mesh->config, cfg)) {
 664                 char *name;
 665                 get_config_string(cfg, &name);
 666
 667                 if(!check_id(name)) {
 668                         logger(DEBUG_ALWAYS, LOG_ERR,
 669                                    "Invalid name for outgoing connection in %s line %d",
 670                                    cfg->file, cfg->line);
 671                         free(name);
 672                         continue;
 673                 }
 674
 675                 bool found = false;
 676
 677                 for list_each(outgoing_t, outgoing, mesh->outgoings) {
 678                         if(!strcmp(outgoing->name, name)) {
 679                                 found = true;
 680                                 outgoing->timeout = 0;
 681                                 break;
 682                         }
 683                 }
 684
 685                 if(!found) {
 686                         outgoing_t *outgoing = xzalloc(sizeof *outgoing);
 687                         outgoing->name = name;
 688                         list_insert_tail(mesh->outgoings, outgoing);
 689                         setup_outgoing_connection(mesh, outgoing);
 690                 }
 691         }
 692
 693         /* Terminate any connections whose outgoing_t is to be deleted. */
 694
 695         for list_each(connection_t, c, mesh->connections) {
 696                 if(c->outgoing && c->outgoing->timeout == -1) {
 697                         c->outgoing = NULL;
 698                         logger(DEBUG_CONNECTIONS, LOG_INFO, "No more outgoing connection to %s", c->name);
 699                         terminate_connection(mesh, c, c->status.active);
 700                 }
 701         }
 702
 703         /* Delete outgoing_ts for which there is no ConnectTo. */
 704
 705         for list_each(outgoing_t, outgoing, mesh->outgoings)
 706                 if(outgoing->timeout == -1)
 707                         list_delete_node(mesh->outgoings, node);
 708 }