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 #ifndef MSG_NOSIGNAL
  40 #define MSG_NOSIGNAL 0
  41 #endif
  42
  43 int addressfamily = AF_UNSPEC;
  44 int seconds_till_retry = 5;
  45 int max_connection_burst = 100;
  46
  47 /* Setup sockets */
  48
  49 static void configure_tcp(connection_t *c) {
  50 #ifdef O_NONBLOCK
  51         int flags = fcntl(c->socket, F_GETFL);
  52
  53         if(fcntl(c->socket, F_SETFL, flags | O_NONBLOCK) < 0) {
  54                 logger(c->mesh, MESHLINK_ERROR, "fcntl for %s: %s", c->hostname, strerror(errno));
  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, "ioctlsocket for %s: %s", c->hostname, sockstrerror(sockerrno));
  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(SOL_IP) && defined(IP_TOS) && defined(IPTOS_LOWDELAY)
  70         int lowdelay = IPTOS_LOWDELAY;
  71         setsockopt(c->socket, SOL_IP, IP_TOS, (void *)&lowdelay, sizeof lowdelay);
  72 #endif
  73 }
  74
  75 static bool bind_to_address(meshlink_handle_t *mesh, connection_t *c) {
  76         int s = -1;
  77
  78         for(int i = 0; i < mesh->listen_sockets && mesh->listen_socket[i].bindto; i++) {
  79                 if(mesh->listen_socket[i].sa.sa.sa_family != c->address.sa.sa_family)
  80                         continue;
  81                 if(s >= 0)
  82                         return false;
  83                 s = i;
  84         }
  85
  86         if(s < 0)
  87                 return false;
  88
  89         sockaddr_t sa = mesh->listen_socket[s].sa;
  90         if(sa.sa.sa_family == AF_INET)
  91                 sa.in.sin_port = 0;
  92         else if(sa.sa.sa_family == AF_INET6)
  93                 sa.in6.sin6_port = 0;
  94
  95         if(bind(c->socket, &sa.sa, SALEN(sa.sa))) {
  96                 logger(mesh, MESHLINK_WARNING, "Can't bind outgoing socket: %s", strerror(errno));
  97                 return false;
  98         }
  99
 100         return true;
 101 }
 102
 103 int setup_listen_socket(const sockaddr_t *sa) {
 104         int nfd;
 105         char *addrstr;
 106         int option;
 107
 108         nfd = socket(sa->sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 109
 110         if(nfd < 0) {
 111                 logger(NULL, MESHLINK_ERROR, "Creating metasocket failed: %s", sockstrerror(sockerrno));
 112                 return -1;
 113         }
 114
 115 #ifdef FD_CLOEXEC
 116         fcntl(nfd, F_SETFD, FD_CLOEXEC);
 117 #endif
 118
 119         /* Optimize TCP settings */
 120
 121         option = 1;
 122         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof option);
 123
 124 #if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
 125         if(sa->sa.sa_family == AF_INET6)
 126                 setsockopt(nfd, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 127 #endif
 128
 129         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
 130                 closesocket(nfd);
 131                 addrstr = sockaddr2hostname(sa);
 132                 logger(NULL, MESHLINK_ERROR, "Can't bind to %s/tcp: %s", addrstr, sockstrerror(sockerrno));
 133                 free(addrstr);
 134                 return -1;
 135         }
 136
 137         if(listen(nfd, 3)) {
 138                 closesocket(nfd);
 139                 logger(NULL, MESHLINK_ERROR, "System call `%s' failed: %s", "listen", sockstrerror(sockerrno));
 140                 return -1;
 141         }
 142
 143         return nfd;
 144 }
 145
 146 int setup_vpn_in_socket(meshlink_handle_t *mesh, const sockaddr_t *sa) {
 147         int nfd;
 148         char *addrstr;
 149         int option;
 150
 151         nfd = socket(sa->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
 152
 153         if(nfd < 0) {
 154                 logger(mesh, MESHLINK_ERROR, "Creating UDP socket failed: %s", sockstrerror(sockerrno));
 155                 return -1;
 156         }
 157
 158 #ifdef FD_CLOEXEC
 159         fcntl(nfd, F_SETFD, FD_CLOEXEC);
 160 #endif
 161
 162 #ifdef O_NONBLOCK
 163         {
 164                 int flags = fcntl(nfd, F_GETFL);
 165
 166                 if(fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0) {
 167                         closesocket(nfd);
 168                         logger(mesh, MESHLINK_ERROR, "System call `%s' failed: %s", "fcntl",
 169                                    strerror(errno));
 170                         return -1;
 171                 }
 172         }
 173 #elif defined(WIN32)
 174         {
 175                 unsigned long arg = 1;
 176                 if(ioctlsocket(nfd, FIONBIO, &arg) != 0) {
 177                         closesocket(nfd);
 178                         logger(mesh, MESHLINK_ERROR, "Call to `%s' failed: %s", "ioctlsocket", sockstrerror(sockerrno));
 179                         return -1;
 180                 }
 181         }
 182 #endif
 183
 184         option = 1;
 185         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof option);
 186         setsockopt(nfd, SOL_SOCKET, SO_BROADCAST, (void *)&option, sizeof option);
 187
 188 #if defined(IPPROTO_IPV6) && defined(IPV6_V6ONLY)
 189         if(sa->sa.sa_family == AF_INET6)
 190                 setsockopt(nfd, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 191 #endif
 192
 193 #if defined(IP_DONTFRAG) && !defined(IP_DONTFRAGMENT)
 194 #define IP_DONTFRAGMENT IP_DONTFRAG
 195 #endif
 196
 197 #if defined(SOL_IP) && defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DO)
 198         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 199                 option = IP_PMTUDISC_DO;
 200                 setsockopt(nfd, SOL_IP, IP_MTU_DISCOVER, (void *)&option, sizeof(option));
 201         }
 202 #elif defined(IPPROTO_IP) && defined(IP_DONTFRAGMENT)
 203         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 204                 option = 1;
 205                 setsockopt(nfd, IPPROTO_IP, IP_DONTFRAGMENT, (void *)&option, sizeof(option));
 206         }
 207 #else
 208 #warning No way to disable IPv4 fragmentation
 209 #endif
 210
 211 #if defined(SOL_IPV6) && defined(IPV6_MTU_DISCOVER) && defined(IPV6_PMTUDISC_DO)
 212         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 213                 option = IPV6_PMTUDISC_DO;
 214                 setsockopt(nfd, SOL_IPV6, IPV6_MTU_DISCOVER, (void *)&option, sizeof(option));
 215         }
 216 #elif defined(IPPROTO_IPV6) && defined(IPV6_DONTFRAG)
 217         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 218                 option = 1;
 219                 setsockopt(nfd, IPPROTO_IPV6, IPV6_DONTFRAG, (void *)&option, sizeof(option));
 220         }
 221 #else
 222 #warning No way to disable IPv6 fragmentation
 223 #endif
 224
 225         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
 226                 closesocket(nfd);
 227                 addrstr = sockaddr2hostname(sa);
 228                 logger(mesh, MESHLINK_ERROR, "Can't bind to %s/udp: %s", addrstr, sockstrerror(sockerrno));
 229                 free(addrstr);
 230                 return -1;
 231         }
 232
 233         return nfd;
 234 } /* int setup_vpn_in_socket */
 235
 236 static void retry_outgoing_handler(event_loop_t *loop, void *data) {
 237         meshlink_handle_t *mesh = loop->data;
 238         outgoing_t *outgoing = data;
 239         setup_outgoing_connection(mesh, outgoing);
 240 }
 241
 242 void retry_outgoing(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 243         outgoing->timeout += 5;
 244
 245         if(outgoing->timeout > mesh->maxtimeout)
 246                 outgoing->timeout = mesh->maxtimeout;
 247
 248         timeout_add(&mesh->loop, &outgoing->ev, retry_outgoing_handler, outgoing, &(struct timeval){outgoing->timeout, rand() % 100000});
 249
 250         logger(mesh, MESHLINK_INFO, "Trying to re-establish outgoing connection in %d seconds", outgoing->timeout);
 251 }
 252
 253 void finish_connecting(meshlink_handle_t *mesh, connection_t *c) {
 254         logger(mesh, MESHLINK_INFO, "Connected to %s (%s)", c->name, c->hostname);
 255
 256         c->last_ping_time = mesh->loop.now.tv_sec;
 257         c->status.connecting = false;
 258
 259         send_id(mesh, c);
 260 }
 261
 262 static void do_outgoing_pipe(meshlink_handle_t *mesh, connection_t *c, char *command) {
 263 #ifndef HAVE_MINGW
 264         int fd[2];
 265
 266         if(socketpair(AF_UNIX, SOCK_STREAM, 0, fd)) {
 267                 logger(mesh, MESHLINK_ERROR, "Could not create socketpair: %s", strerror(errno));
 268                 return;
 269         }
 270
 271         if(fork()) {
 272                 c->socket = fd[0];
 273                 close(fd[1]);
 274                 logger(mesh, MESHLINK_DEBUG, "Using proxy %s", command);
 275                 return;
 276         }
 277
 278         close(0);
 279         close(1);
 280         close(fd[0]);
 281         dup2(fd[1], 0);
 282         dup2(fd[1], 1);
 283         close(fd[1]);
 284
 285         // Other filedescriptors should be closed automatically by CLOEXEC
 286
 287         char *host = NULL;
 288         char *port = NULL;
 289
 290         sockaddr2str(&c->address, &host, &port);
 291         setenv("REMOTEADDRESS", host, true);
 292         setenv("REMOTEPORT", port, true);
 293         setenv("NODE", c->name, true);
 294         setenv("NAME", mesh->self->name, true);
 295
 296         int result = system(command);
 297         if(result < 0)
 298                 logger(mesh, MESHLINK_ERROR, "Could not execute %s: %s", command, strerror(errno));
 299         else if(result)
 300                 logger(mesh, MESHLINK_ERROR, "%s exited with non-zero status %d", command, result);
 301         exit(result);
 302 #else
 303         logger(mesh, MESHLINK_ERROR, "Proxy type exec not supported on this platform!");
 304         return;
 305 #endif
 306 }
 307
 308 static void handle_meta_write(meshlink_handle_t *mesh, connection_t *c) {
 309         if(c->outbuf.len <= c->outbuf.offset)
 310                 return;
 311
 312         ssize_t outlen = send(c->socket, c->outbuf.data + c->outbuf.offset, c->outbuf.len - c->outbuf.offset, MSG_NOSIGNAL);
 313         if(outlen <= 0) {
 314                 if(!errno || errno == EPIPE) {
 315                         logger(mesh, MESHLINK_INFO, "Connection closed by %s (%s)", c->name, c->hostname);
 316                 } else if(sockwouldblock(sockerrno)) {
 317                         logger(mesh, MESHLINK_DEBUG, "Sending %d bytes to %s (%s) would block", c->outbuf.len - c->outbuf.offset, c->name, c->hostname);
 318                         return;
 319                 } else {
 320                         logger(mesh, MESHLINK_ERROR, "Could not send %d bytes of data to %s (%s): %s", c->outbuf.len - c->outbuf.offset, c->name, c->hostname, strerror(errno));
 321                 }
 322
 323                 terminate_connection(mesh, c, c->status.active);
 324                 return;
 325         }
 326
 327         buffer_read(&c->outbuf, outlen);
 328         if(!c->outbuf.len)
 329                 io_set(&mesh->loop, &c->io, IO_READ);
 330 }
 331
 332 static void handle_meta_io(event_loop_t *loop, void *data, int flags) {
 333         meshlink_handle_t *mesh = loop->data;
 334         connection_t *c = data;
 335
 336         if(c->status.connecting) {
 337                 c->status.connecting = false;
 338
 339                 int result;
 340                 socklen_t len = sizeof result;
 341                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 342
 343                 if(!result)
 344                         finish_connecting(mesh, c);
 345                 else {
 346                         logger(mesh, MESHLINK_DEBUG, "Error while connecting to %s (%s): %s", c->name, c->hostname, sockstrerror(result));
 347                         terminate_connection(mesh, c, false);
 348                         return;
 349                 }
 350         }
 351
 352         if(flags & IO_WRITE)
 353                 handle_meta_write(mesh, c);
 354         else
 355                 handle_meta_connection_data(mesh, c);
 356 }
 357
 358 bool do_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 359         char *address, *port, *space;
 360         struct addrinfo *proxyai = NULL;
 361         int result;
 362
 363 begin:
 364         if(!outgoing->ai) {
 365                 if(!outgoing->cfg) {
 366                         logger(mesh, MESHLINK_ERROR, "Could not set up a meta connection to %s", outgoing->name);
 367                         retry_outgoing(mesh, outgoing);
 368                         return false;
 369                 }
 370
 371                 get_config_string(outgoing->cfg, &address);
 372
 373                 space = strchr(address, ' ');
 374                 if(space) {
 375                         port = xstrdup(space + 1);
 376                         *space = 0;
 377                 } else {
 378                         // TODO: Only allow Address statements?
 379                         if(!get_config_string(lookup_config(outgoing->config_tree, "Port"), &port)) {
 380                                 logger(mesh, MESHLINK_ERROR, "No Port known for %s", outgoing->name);
 381                                 retry_outgoing(mesh, outgoing);
 382                                 return false;
 383                         }
 384                 }
 385
 386                 outgoing->ai = str2addrinfo(address, port, SOCK_STREAM);
 387                 free(address);
 388                 free(port);
 389
 390                 outgoing->aip = outgoing->ai;
 391                 outgoing->cfg = lookup_config_next(outgoing->config_tree, outgoing->cfg);
 392         }
 393
 394         if(!outgoing->aip) {
 395                 if(outgoing->ai)
 396                         freeaddrinfo(outgoing->ai);
 397                 outgoing->ai = NULL;
 398                 goto begin;
 399         }
 400
 401         connection_t *c = new_connection();
 402         c->outgoing = outgoing;
 403
 404         memcpy(&c->address, outgoing->aip->ai_addr, outgoing->aip->ai_addrlen);
 405         outgoing->aip = outgoing->aip->ai_next;
 406
 407         c->hostname = sockaddr2hostname(&c->address);
 408
 409         logger(mesh, MESHLINK_INFO, "Trying to connect to %s (%s)", outgoing->name, c->hostname);
 410
 411         if(!mesh->proxytype) {
 412                 c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 413                 configure_tcp(c);
 414         } else if(mesh->proxytype == PROXY_EXEC) {
 415                 do_outgoing_pipe(mesh, c, mesh->proxyhost);
 416         } else {
 417                 proxyai = str2addrinfo(mesh->proxyhost, mesh->proxyport, SOCK_STREAM);
 418                 if(!proxyai) {
 419                         free_connection(c);
 420                         goto begin;
 421                 }
 422                 logger(mesh, MESHLINK_INFO, "Using proxy at %s port %s", mesh->proxyhost, mesh->proxyport);
 423                 c->socket = socket(proxyai->ai_family, SOCK_STREAM, IPPROTO_TCP);
 424                 configure_tcp(c);
 425         }
 426
 427         if(c->socket == -1) {
 428                 logger(mesh, MESHLINK_ERROR, "Creating socket for %s failed: %s", c->hostname, sockstrerror(sockerrno));
 429                 free_connection(c);
 430                 goto begin;
 431         }
 432
 433 #ifdef FD_CLOEXEC
 434         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
 435 #endif
 436
 437         if(mesh->proxytype != PROXY_EXEC) {
 438 #if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
 439                 int option = 1;
 440                 if(c->address.sa.sa_family == AF_INET6)
 441                         setsockopt(c->socket, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 442 #endif
 443
 444                 bind_to_address(mesh, c);
 445         }
 446
 447         /* Connect */
 448
 449         if(!mesh->proxytype) {
 450                 result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
 451         } else if(mesh->proxytype == PROXY_EXEC) {
 452                 result = 0;
 453         } else {
 454                 result = connect(c->socket, proxyai->ai_addr, proxyai->ai_addrlen);
 455                 freeaddrinfo(proxyai);
 456         }
 457
 458         if(result == -1 && !sockinprogress(sockerrno)) {
 459                 logger(mesh, MESHLINK_ERROR, "Could not connect to %s (%s): %s", outgoing->name, c->hostname, sockstrerror(sockerrno));
 460                 free_connection(c);
 461
 462                 goto begin;
 463         }
 464
 465         /* Now that there is a working socket, fill in the rest and register this connection. */
 466
 467         c->status.connecting = true;
 468         c->name = xstrdup(outgoing->name);
 469         c->outcompression = mesh->self->connection->outcompression;
 470         c->last_ping_time = mesh->loop.now.tv_sec;
 471
 472         connection_add(mesh, c);
 473
 474         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ|IO_WRITE);
 475
 476         return true;
 477 }
 478
 479 // Find edges pointing to this node, and use them to build a list of unique, known addresses.
 480 static struct addrinfo *get_known_addresses(node_t *n) {
 481         struct addrinfo *ai = NULL;
 482
 483         for splay_each(edge_t, e, n->edge_tree) {
 484                 if(!e->reverse)
 485                         continue;
 486
 487                 bool found = false;
 488                 for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 489                         if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
 490                                 found = true;
 491                                 break;
 492                         }
 493                 }
 494                 if(found)
 495                         continue;
 496
 497                 struct addrinfo *nai = xzalloc(sizeof *nai);
 498                 if(ai)
 499                         ai->ai_next = nai;
 500                 ai = nai;
 501                 ai->ai_family = e->reverse->address.sa.sa_family;
 502                 ai->ai_socktype = SOCK_STREAM;
 503                 ai->ai_protocol = IPPROTO_TCP;
 504                 ai->ai_addrlen = SALEN(e->reverse->address.sa);
 505                 ai->ai_addr = xmalloc(ai->ai_addrlen);
 506                 memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
 507         }
 508
 509         return ai;
 510 }
 511
 512 void setup_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 513         bool blacklisted = false;
 514         timeout_del(&mesh->loop, &outgoing->ev);
 515
 516         node_t *n = lookup_node(mesh, outgoing->name);
 517
 518         if(n && n->connection) {
 519                 logger(mesh, MESHLINK_INFO, "Already connected to %s", outgoing->name);
 520
 521                 n->connection->outgoing = outgoing;
 522                 return;
 523         }
 524
 525         exit_configuration(&outgoing->config_tree); // discard old configuration if present
 526         init_configuration(&outgoing->config_tree);
 527         read_host_config(mesh, outgoing->config_tree, outgoing->name);
 528         outgoing->cfg = lookup_config(outgoing->config_tree, "Address");
 529
 530         get_config_bool(lookup_config(outgoing->config_tree, "blacklisted"), &blacklisted);
 531         if (blacklisted) return;
 532
 533         if(!outgoing->cfg) {
 534                 if(n)
 535                         outgoing->aip = outgoing->ai = get_known_addresses(n);
 536                 if(!outgoing->ai) {
 537                         logger(mesh, MESHLINK_ERROR, "No address known for %s", outgoing->name);
 538                         return;
 539                 }
 540         }
 541
 542         do_outgoing_connection(mesh, outgoing);
 543 }
 544
 545 /*
 546   accept a new tcp connect and create a
 547   new connection
 548 */
 549 void handle_new_meta_connection(event_loop_t *loop, void *data, int flags) {
 550         meshlink_handle_t *mesh = loop->data;
 551         listen_socket_t *l = data;
 552         connection_t *c;
 553         sockaddr_t sa;
 554         int fd;
 555         socklen_t len = sizeof sa;
 556
 557         fd = accept(l->tcp.fd, &sa.sa, &len);
 558
 559         if(fd < 0) {
 560                 if(errno == EINVAL) { // TODO: check if Windows agrees
 561                         event_loop_stop(loop);
 562                         return;
 563                 }
 564
 565                 logger(mesh, MESHLINK_ERROR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 566                 return;
 567         }
 568
 569         sockaddrunmap(&sa);
 570
 571         // Check if we get many connections from the same host
 572
 573         static sockaddr_t prev_sa;
 574         static int tarpit = -1;
 575
 576         if(tarpit >= 0) {
 577                 closesocket(tarpit);
 578                 tarpit = -1;
 579         }
 580
 581         if(!sockaddrcmp_noport(&sa, &prev_sa)) {
 582                 static int samehost_burst;
 583                 static int samehost_burst_time;
 584
 585                 if(mesh->loop.now.tv_sec - samehost_burst_time > samehost_burst)
 586                         samehost_burst = 0;
 587                 else
 588                         samehost_burst -= mesh->loop.now.tv_sec - samehost_burst_time;
 589
 590                 samehost_burst_time = mesh->loop.now.tv_sec;
 591                 samehost_burst++;
 592
 593                 if(samehost_burst > max_connection_burst) {
 594                         tarpit = fd;
 595                         return;
 596                 }
 597         }
 598
 599         memcpy(&prev_sa, &sa, sizeof sa);
 600
 601         // Check if we get many connections from different hosts
 602
 603         static int connection_burst;
 604         static int connection_burst_time;
 605
 606         if(mesh->loop.now.tv_sec - connection_burst_time > connection_burst)
 607                 connection_burst = 0;
 608         else
 609                 connection_burst -= mesh->loop.now.tv_sec - connection_burst_time;
 610
 611         connection_burst_time = mesh->loop.now.tv_sec;
 612         connection_burst++;
 613
 614         if(connection_burst >= max_connection_burst) {
 615                 connection_burst = max_connection_burst;
 616                 tarpit = fd;
 617                 return;
 618         }
 619
 620         // Accept the new connection
 621
 622         c = new_connection();
 623         c->name = xstrdup("<unknown>");
 624         c->outcompression = mesh->self->connection->outcompression;
 625
 626         c->address = sa;
 627         c->hostname = sockaddr2hostname(&sa);
 628         c->socket = fd;
 629         c->last_ping_time = mesh->loop.now.tv_sec;
 630
 631         logger(mesh, MESHLINK_INFO, "Connection from %s", c->hostname);
 632
 633         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
 634
 635         configure_tcp(c);
 636
 637         connection_add(mesh, c);
 638
 639         c->allow_request = ID;
 640         send_id(mesh, c);
 641 }
 642
 643 static void free_outgoing(outgoing_t *outgoing) {
 644         meshlink_handle_t *mesh = outgoing->mesh;
 645
 646         timeout_del(&mesh->loop, &outgoing->ev);
 647
 648         if(outgoing->ai)
 649                 freeaddrinfo(outgoing->ai);
 650
 651         if(outgoing->config_tree)
 652                 exit_configuration(&outgoing->config_tree);
 653
 654         if(outgoing->name)
 655                 free(outgoing->name);
 656
 657         free(outgoing);
 658 }
 659
 660 void try_outgoing_connections(meshlink_handle_t *mesh) {
 661         /* If there is no outgoing list yet, create one. Otherwise, mark all outgoings as deleted. */
 662
 663         if(!mesh->outgoings) {
 664                 mesh->outgoings = list_alloc((list_action_t)free_outgoing);
 665         } else {
 666                 for list_each(outgoing_t, outgoing, mesh->outgoings)
 667                         outgoing->timeout = -1;
 668         }
 669
 670         /* Make sure there is one outgoing_t in the list for each ConnectTo. */
 671
 672         // TODO: Drop support for ConnectTo since AutoConnect is now always on?
 673         for(config_t *cfg = lookup_config(mesh->config, "ConnectTo"); cfg; cfg = lookup_config_next(mesh->config, cfg)) {
 674                 char *name;
 675                 get_config_string(cfg, &name);
 676
 677                 if(!check_id(name)) {
 678                         logger(mesh, MESHLINK_ERROR,
 679                                    "Invalid name for outgoing connection in %s line %d",
 680                                    cfg->file, cfg->line);
 681                         free(name);
 682                         continue;
 683                 }
 684
 685                 bool found = false;
 686
 687                 for list_each(outgoing_t, outgoing, mesh->outgoings) {
 688                         if(!strcmp(outgoing->name, name)) {
 689                                 found = true;
 690                                 outgoing->timeout = 0;
 691                                 break;
 692                         }
 693                 }
 694
 695                 if(!found) {
 696                         outgoing_t *outgoing = xzalloc(sizeof *outgoing);
 697                         outgoing->mesh = mesh;
 698                         outgoing->name = name;
 699                         list_insert_tail(mesh->outgoings, outgoing);
 700                         setup_outgoing_connection(mesh, outgoing);
 701                 }
 702         }
 703
 704         /* Terminate any connections whose outgoing_t is to be deleted. */
 705
 706         for list_each(connection_t, c, mesh->connections) {
 707                 if(c->outgoing && c->outgoing->timeout == -1) {
 708                         c->outgoing = NULL;
 709                         logger(mesh, MESHLINK_INFO, "No more outgoing connection to %s", c->name);
 710                         terminate_connection(mesh, c, c->status.active);
 711                 }
 712         }
 713
 714         /* Delete outgoing_ts for which there is no ConnectTo. */
 715
 716         for list_each(outgoing_t, outgoing, mesh->outgoings)
 717                 if(outgoing->timeout == -1)
 718                         list_delete_node(mesh->outgoings, node);
 719 }