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 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, "System call `%s' failed: %s", "fcntl", strerror(errno));
  55         }
  56
  57 #elif defined(WIN32)
  58         unsigned long arg = 1;
  59
  60         if(ioctlsocket(c->socket, FIONBIO, &arg) != 0) {
  61                 logger(c->mesh, MESHLINK_ERROR, "System call `%s' failed: %s", "ioctlsocket", sockstrerror(sockerrno));
  62         }
  63
  64 #endif
  65
  66 #if defined(SOL_TCP) && defined(TCP_NODELAY)
  67         int nodelay = 1;
  68         setsockopt(c->socket, SOL_TCP, TCP_NODELAY, (void *)&nodelay, sizeof(nodelay));
  69 #endif
  70
  71 #if defined(IP_TOS) && defined(IPTOS_LOWDELAY)
  72         int lowdelay = IPTOS_LOWDELAY;
  73         setsockopt(c->socket, IPPROTO_IP, IP_TOS, (void *)&lowdelay, sizeof(lowdelay));
  74 #endif
  75 }
  76
  77 static bool bind_to_address(meshlink_handle_t *mesh, connection_t *c) {
  78         int s = -1;
  79
  80         for(int i = 0; i < mesh->listen_sockets && mesh->listen_socket[i].bindto; i++) {
  81                 if(mesh->listen_socket[i].sa.sa.sa_family != c->address.sa.sa_family) {
  82                         continue;
  83                 }
  84
  85                 if(s >= 0) {
  86                         return false;
  87                 }
  88
  89                 s = i;
  90         }
  91
  92         if(s < 0) {
  93                 return false;
  94         }
  95
  96         sockaddr_t sa = mesh->listen_socket[s].sa;
  97
  98         if(sa.sa.sa_family == AF_INET) {
  99                 sa.in.sin_port = 0;
 100         } else if(sa.sa.sa_family == AF_INET6) {
 101                 sa.in6.sin6_port = 0;
 102         }
 103
 104         if(bind(c->socket, &sa.sa, SALEN(sa.sa))) {
 105                 logger(mesh, MESHLINK_WARNING, "Can't bind outgoing socket: %s", strerror(errno));
 106                 return false;
 107         }
 108
 109         return true;
 110 }
 111
 112 int setup_listen_socket(const sockaddr_t *sa) {
 113         int nfd;
 114         char *addrstr;
 115         int option;
 116
 117         nfd = socket(sa->sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 118
 119         if(nfd < 0) {
 120                 logger(NULL, MESHLINK_ERROR, "Creating metasocket failed: %s", sockstrerror(sockerrno));
 121                 return -1;
 122         }
 123
 124 #ifdef FD_CLOEXEC
 125         fcntl(nfd, F_SETFD, FD_CLOEXEC);
 126 #endif
 127
 128         /* Optimize TCP settings */
 129
 130         option = 1;
 131         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof(option));
 132
 133 #if defined(IPV6_V6ONLY)
 134
 135         if(sa->sa.sa_family == AF_INET6) {
 136                 setsockopt(nfd, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
 137         }
 138
 139 #else
 140 #warning IPV6_V6ONLY not defined
 141 #endif
 142
 143         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
 144                 closesocket(nfd);
 145                 addrstr = sockaddr2hostname(sa);
 146                 logger(NULL, MESHLINK_ERROR, "Can't bind to %s/tcp: %s", addrstr, sockstrerror(sockerrno));
 147                 free(addrstr);
 148                 return -1;
 149         }
 150
 151         if(listen(nfd, 3)) {
 152                 closesocket(nfd);
 153                 logger(NULL, MESHLINK_ERROR, "System call `%s' failed: %s", "listen", sockstrerror(sockerrno));
 154                 return -1;
 155         }
 156
 157         return nfd;
 158 }
 159
 160 int setup_vpn_in_socket(meshlink_handle_t *mesh, const sockaddr_t *sa) {
 161         int nfd;
 162         char *addrstr;
 163         int option;
 164
 165         nfd = socket(sa->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
 166
 167         if(nfd < 0) {
 168                 logger(mesh, MESHLINK_ERROR, "Creating UDP socket failed: %s", sockstrerror(sockerrno));
 169                 return -1;
 170         }
 171
 172 #ifdef FD_CLOEXEC
 173         fcntl(nfd, F_SETFD, FD_CLOEXEC);
 174 #endif
 175
 176 #ifdef O_NONBLOCK
 177         {
 178                 int flags = fcntl(nfd, F_GETFL);
 179
 180                 if(fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0) {
 181                         closesocket(nfd);
 182                         logger(mesh, MESHLINK_ERROR, "System call `%s' failed: %s", "fcntl",
 183                                strerror(errno));
 184                         return -1;
 185                 }
 186         }
 187 #elif defined(WIN32)
 188         {
 189                 unsigned long arg = 1;
 190
 191                 if(ioctlsocket(nfd, FIONBIO, &arg) != 0) {
 192                         closesocket(nfd);
 193                         logger(mesh, MESHLINK_ERROR, "Call to `%s' failed: %s", "ioctlsocket", sockstrerror(sockerrno));
 194                         return -1;
 195                 }
 196         }
 197 #endif
 198
 199         option = 1;
 200         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof(option));
 201         setsockopt(nfd, SOL_SOCKET, SO_BROADCAST, (void *)&option, sizeof(option));
 202
 203 #if defined(IPV6_V6ONLY)
 204
 205         if(sa->sa.sa_family == AF_INET6) {
 206                 setsockopt(nfd, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
 207         }
 208
 209 #endif
 210
 211 #if defined(IP_DONTFRAG) && !defined(IP_DONTFRAGMENT)
 212 #define IP_DONTFRAGMENT IP_DONTFRAG
 213 #endif
 214
 215 #if defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DO)
 216
 217         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 218                 option = IP_PMTUDISC_DO;
 219                 setsockopt(nfd, IPPROTO_IP, IP_MTU_DISCOVER, (void *)&option, sizeof(option));
 220         }
 221
 222 #elif defined(IP_DONTFRAGMENT)
 223
 224         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 225                 option = 1;
 226                 setsockopt(nfd, IPPROTO_IP, IP_DONTFRAGMENT, (void *)&option, sizeof(option));
 227         }
 228
 229 #else
 230 #warning No way to disable IPv4 fragmentation
 231 #endif
 232
 233 #if defined(IPV6_MTU_DISCOVER) && defined(IPV6_PMTUDISC_DO)
 234
 235         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 236                 option = IPV6_PMTUDISC_DO;
 237                 setsockopt(nfd, IPPROTO_IPV6, IPV6_MTU_DISCOVER, (void *)&option, sizeof(option));
 238         }
 239
 240 #elif defined(IPV6_DONTFRAG)
 241
 242         if(mesh->self->options & OPTION_PMTU_DISCOVERY) {
 243                 option = 1;
 244                 setsockopt(nfd, IPPROTO_IPV6, IPV6_DONTFRAG, (void *)&option, sizeof(option));
 245         }
 246
 247 #else
 248 #warning No way to disable IPv6 fragmentation
 249 #endif
 250
 251         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
 252                 closesocket(nfd);
 253                 addrstr = sockaddr2hostname(sa);
 254                 logger(mesh, MESHLINK_ERROR, "Can't bind to %s/udp: %s", addrstr, sockstrerror(sockerrno));
 255                 free(addrstr);
 256                 return -1;
 257         }
 258
 259         return nfd;
 260 } /* int setup_vpn_in_socket */
 261
 262 static void retry_outgoing_handler(event_loop_t *loop, void *data) {
 263         meshlink_handle_t *mesh = loop->data;
 264         outgoing_t *outgoing = data;
 265         setup_outgoing_connection(mesh, outgoing);
 266 }
 267
 268 void retry_outgoing(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 269         outgoing->timeout += 5;
 270
 271         if(outgoing->timeout > mesh->maxtimeout) {
 272                 outgoing->timeout = mesh->maxtimeout;
 273         }
 274
 275         timeout_add(&mesh->loop, &outgoing->ev, retry_outgoing_handler, outgoing, &(struct timeval) {
 276                 outgoing->timeout, rand() % 100000
 277         });
 278
 279         logger(mesh, MESHLINK_INFO, "Trying to re-establish outgoing connection in %d seconds", outgoing->timeout);
 280 }
 281
 282 void finish_connecting(meshlink_handle_t *mesh, connection_t *c) {
 283         logger(mesh, MESHLINK_INFO, "Connected to %s", c->name);
 284
 285         c->last_ping_time = mesh->loop.now.tv_sec;
 286         c->status.connecting = false;
 287
 288         send_id(mesh, c);
 289 }
 290
 291 static void handle_meta_write(meshlink_handle_t *mesh, connection_t *c) {
 292         if(c->outbuf.len <= c->outbuf.offset) {
 293                 return;
 294         }
 295
 296         ssize_t outlen = send(c->socket, c->outbuf.data + c->outbuf.offset, c->outbuf.len - c->outbuf.offset, MSG_NOSIGNAL);
 297
 298         if(outlen <= 0) {
 299                 if(!errno || errno == EPIPE) {
 300                         logger(mesh, MESHLINK_INFO, "Connection closed by %s", c->name);
 301                 } else if(sockwouldblock(sockerrno)) {
 302                         logger(mesh, MESHLINK_DEBUG, "Sending %lu bytes to %s would block", (unsigned long)(c->outbuf.len - c->outbuf.offset), c->name);
 303                         return;
 304                 } else {
 305                         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));
 306                 }
 307
 308                 terminate_connection(mesh, c, c->status.active);
 309                 return;
 310         }
 311
 312         buffer_read(&c->outbuf, outlen);
 313
 314         if(!c->outbuf.len) {
 315                 io_set(&mesh->loop, &c->io, IO_READ);
 316         }
 317 }
 318
 319 static void handle_meta_io(event_loop_t *loop, void *data, int flags) {
 320         meshlink_handle_t *mesh = loop->data;
 321         connection_t *c = data;
 322
 323         if(c->status.connecting) {
 324                 c->status.connecting = false;
 325
 326                 int result;
 327                 socklen_t len = sizeof(result);
 328                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 329
 330                 if(!result) {
 331                         finish_connecting(mesh, c);
 332                 } else {
 333                         logger(mesh, MESHLINK_DEBUG, "Error while connecting to %s: %s", c->name, sockstrerror(result));
 334                         terminate_connection(mesh, c, false);
 335                         return;
 336                 }
 337         }
 338
 339         if(flags & IO_WRITE) {
 340                 handle_meta_write(mesh, c);
 341         } else {
 342                 handle_meta_connection_data(mesh, c);
 343         }
 344 }
 345
 346 // Find edges pointing to this node, and use them to build a list of unique, known addresses.
 347 static struct addrinfo *get_known_addresses(node_t *n) {
 348         struct addrinfo *ai = NULL;
 349
 350         for splay_each(edge_t, e, n->edge_tree) {
 351                 if(!e->reverse) {
 352                         continue;
 353                 }
 354
 355                 bool found = false;
 356
 357                 for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 358                         if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
 359                                 found = true;
 360                                 break;
 361                         }
 362                 }
 363
 364                 if(found) {
 365                         continue;
 366                 }
 367
 368                 // Create a new struct addrinfo, and put it at the head of the list.
 369                 struct addrinfo *nai = xzalloc(sizeof(*nai) + SALEN(e->reverse->address.sa));
 370                 nai->ai_next = ai;
 371                 ai = nai;
 372
 373                 ai->ai_family = e->reverse->address.sa.sa_family;
 374                 ai->ai_socktype = SOCK_STREAM;
 375                 ai->ai_protocol = IPPROTO_TCP;
 376                 ai->ai_addrlen = SALEN(e->reverse->address.sa);
 377                 ai->ai_addr = (struct sockaddr *)(nai + 1);
 378                 memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
 379         }
 380
 381         return ai;
 382 }
 383
 384 // Free struct addrinfo list from get_known_addresses().
 385 static void free_known_addresses(struct addrinfo *ai) {
 386         for(struct addrinfo *aip = ai, *next; aip; aip = next) {
 387                 next = aip->ai_next;
 388                 free(aip);
 389         }
 390 }
 391
 392 static bool get_recent(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 393         node_t *n = lookup_node(mesh, outgoing->name);
 394
 395         if(!n) {
 396                 return false;
 397         }
 398
 399         outgoing->ai = get_known_addresses(n);
 400         outgoing->aip = outgoing->ai;
 401         return outgoing->aip;
 402 }
 403
 404 static bool get_next_ai(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 405         if(!outgoing->ai) {
 406                 char *address = NULL;
 407
 408                 if(get_config_string(outgoing->cfg, &address)) {
 409                         char *port;
 410                         char *space = strchr(address, ' ');
 411
 412                         if(space) {
 413                                 port = xstrdup(space + 1);
 414                                 *space = 0;
 415                         } else {
 416                                 if(!get_config_string(lookup_config(outgoing->config_tree, "Port"), &port)) {
 417                                         logger(mesh, MESHLINK_ERROR, "No Port known for %s", outgoing->name);
 418                                         return false;
 419                                 }
 420                         }
 421
 422                         outgoing->ai = str2addrinfo(address, port, SOCK_STREAM);
 423                         free(port);
 424                         free(address);
 425                 }
 426
 427                 outgoing->aip = outgoing->ai;
 428         } else {
 429                 outgoing->aip = outgoing->aip->ai_next;
 430         }
 431
 432         return outgoing->aip;
 433 }
 434
 435 static bool get_next_cfg(meshlink_handle_t *mesh, outgoing_t *outgoing, char *variable) {
 436         (void)mesh;
 437
 438         if(!outgoing->cfg) {
 439                 outgoing->cfg = lookup_config(outgoing->config_tree, variable);
 440         } else {
 441                 outgoing->cfg = lookup_config_next(outgoing->config_tree, outgoing->cfg);
 442         }
 443
 444         return outgoing->cfg;
 445 }
 446
 447 static bool get_next_outgoing_address(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 448         bool start = false;
 449
 450         if(outgoing->state == OUTGOING_START) {
 451                 start = true;
 452                 outgoing->state = OUTGOING_CANONICAL;
 453         }
 454
 455         if(outgoing->state == OUTGOING_CANONICAL) {
 456                 if(outgoing->aip || get_next_cfg(mesh, outgoing, "CanonicalAddress")) {
 457                         if(get_next_ai(mesh, outgoing)) {
 458                                 return true;
 459                         } else {
 460                                 freeaddrinfo(outgoing->ai);
 461                                 outgoing->ai = NULL;
 462                                 outgoing->aip = NULL;
 463                         }
 464                 }
 465
 466                 outgoing->state = OUTGOING_RECENT;
 467         }
 468
 469         if(outgoing->state == OUTGOING_RECENT) {
 470                 if(outgoing->aip || get_next_cfg(mesh, outgoing, "Address")) {
 471                         if(get_next_ai(mesh, outgoing)) {
 472                                 return true;
 473                         } else {
 474                                 freeaddrinfo(outgoing->ai);
 475                                 outgoing->ai = NULL;
 476                                 outgoing->aip = NULL;
 477                         }
 478                 }
 479
 480                 outgoing->state = OUTGOING_KNOWN;
 481         }
 482
 483         if(outgoing->state == OUTGOING_KNOWN) {
 484                 if(outgoing->aip || get_recent(mesh, outgoing)) {
 485                         if(get_next_ai(mesh, outgoing)) {
 486                                 return true;
 487                         } else {
 488                                 free_known_addresses(outgoing->ai);
 489                                 outgoing->ai = NULL;
 490                                 outgoing->aip = NULL;
 491                         }
 492                 }
 493
 494                 outgoing->state = OUTGOING_END;
 495         }
 496
 497         if(start) {
 498                 outgoing->state = OUTGOING_NO_KNOWN_ADDRESSES;
 499         }
 500
 501         return false;
 502 }
 503
 504 bool do_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 505         struct addrinfo *proxyai = NULL;
 506         int result;
 507
 508 begin:
 509
 510         if(!get_next_outgoing_address(mesh, outgoing)) {
 511                 if(outgoing->state == OUTGOING_NO_KNOWN_ADDRESSES) {
 512                         logger(mesh, MESHLINK_ERROR, "No known addresses for %s", outgoing->name);
 513                 } else {
 514                         logger(mesh, MESHLINK_ERROR, "Could not set up a meta connection to %s", outgoing->name);
 515                         retry_outgoing(mesh, outgoing);
 516                 }
 517
 518                 return false;
 519         }
 520
 521         connection_t *c = new_connection();
 522         c->outgoing = outgoing;
 523
 524         memcpy(&c->address, outgoing->aip->ai_addr, outgoing->aip->ai_addrlen);
 525
 526         char *hostname = sockaddr2hostname(&c->address);
 527
 528         logger(mesh, MESHLINK_INFO, "Trying to connect to %s at %s", outgoing->name, hostname);
 529
 530         if(!mesh->proxytype) {
 531                 c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 532                 configure_tcp(c);
 533         } else {
 534                 proxyai = str2addrinfo(mesh->proxyhost, mesh->proxyport, SOCK_STREAM);
 535
 536                 if(!proxyai) {
 537                         free_connection(c);
 538                         free(hostname);
 539                         goto begin;
 540                 }
 541
 542                 logger(mesh, MESHLINK_INFO, "Using proxy at %s port %s", mesh->proxyhost, mesh->proxyport);
 543                 c->socket = socket(proxyai->ai_family, SOCK_STREAM, IPPROTO_TCP);
 544                 configure_tcp(c);
 545         }
 546
 547         if(c->socket == -1) {
 548                 logger(mesh, MESHLINK_ERROR, "Creating socket for %s at %s failed: %s", c->name, hostname, sockstrerror(sockerrno));
 549                 free_connection(c);
 550                 free(hostname);
 551                 goto begin;
 552         }
 553
 554         free(hostname);
 555
 556 #ifdef FD_CLOEXEC
 557         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
 558 #endif
 559
 560 #if defined(IPV6_V6ONLY)
 561
 562         if(c->address.sa.sa_family == AF_INET6) {
 563                 static const int option = 1;
 564                 setsockopt(c->socket, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
 565         }
 566
 567 #endif
 568
 569         bind_to_address(mesh, c);
 570
 571         /* Connect */
 572
 573         if(!mesh->proxytype) {
 574                 result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
 575         } else {
 576                 result = connect(c->socket, proxyai->ai_addr, proxyai->ai_addrlen);
 577                 freeaddrinfo(proxyai);
 578         }
 579
 580         if(result == -1 && !sockinprogress(sockerrno)) {
 581                 logger(mesh, MESHLINK_ERROR, "Could not connect to %s: %s", outgoing->name, sockstrerror(sockerrno));
 582                 free_connection(c);
 583
 584                 goto begin;
 585         }
 586
 587         /* Now that there is a working socket, fill in the rest and register this connection. */
 588
 589         c->status.connecting = true;
 590         c->name = xstrdup(outgoing->name);
 591         c->outcompression = mesh->self->connection->outcompression;
 592         c->last_ping_time = mesh->loop.now.tv_sec;
 593
 594         connection_add(mesh, c);
 595
 596         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ | IO_WRITE);
 597
 598         return true;
 599 }
 600
 601 void setup_outgoing_connection(meshlink_handle_t *mesh, outgoing_t *outgoing) {
 602         bool blacklisted = false;
 603         timeout_del(&mesh->loop, &outgoing->ev);
 604
 605         node_t *n = lookup_node(mesh, outgoing->name);
 606
 607         if(n && n->connection) {
 608                 logger(mesh, MESHLINK_INFO, "Already connected to %s", outgoing->name);
 609
 610                 n->connection->outgoing = outgoing;
 611                 return;
 612         }
 613
 614
 615         if(outgoing->ai) {
 616                 if(outgoing->state == OUTGOING_KNOWN) {
 617                         free_known_addresses(outgoing->ai);
 618                 } else {
 619                         freeaddrinfo(outgoing->ai);
 620                 }
 621         }
 622
 623         outgoing->cfg = NULL;
 624
 625         exit_configuration(&outgoing->config_tree); // discard old configuration if present
 626         init_configuration(&outgoing->config_tree);
 627         read_host_config(mesh, outgoing->config_tree, outgoing->name);
 628         get_config_bool(lookup_config(outgoing->config_tree, "blacklisted"), &blacklisted);
 629
 630         outgoing->state = OUTGOING_START;
 631
 632         if(blacklisted) {
 633                 return;
 634         }
 635
 636         do_outgoing_connection(mesh, outgoing);
 637 }
 638
 639 /*
 640   accept a new tcp connect and create a
 641   new connection
 642 */
 643 void handle_new_meta_connection(event_loop_t *loop, void *data, int flags) {
 644         (void)flags;
 645         meshlink_handle_t *mesh = loop->data;
 646         listen_socket_t *l = data;
 647         connection_t *c;
 648         sockaddr_t sa = {0};
 649         int fd;
 650         socklen_t len = sizeof(sa);
 651
 652         fd = accept(l->tcp.fd, &sa.sa, &len);
 653
 654         if(fd < 0) {
 655                 if(errno == EINVAL) { // TODO: check if Windows agrees
 656                         event_loop_stop(loop);
 657                         return;
 658                 }
 659
 660                 logger(mesh, MESHLINK_ERROR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 661                 return;
 662         }
 663
 664         sockaddrunmap(&sa);
 665
 666         // Check if we get many connections from the same host
 667
 668         static sockaddr_t prev_sa;
 669         static int tarpit = -1;
 670
 671         if(tarpit >= 0) {
 672                 closesocket(tarpit);
 673                 tarpit = -1;
 674         }
 675
 676         if(!sockaddrcmp_noport(&sa, &prev_sa)) {
 677                 static int samehost_burst;
 678                 static int samehost_burst_time;
 679
 680                 if(mesh->loop.now.tv_sec - samehost_burst_time > samehost_burst) {
 681                         samehost_burst = 0;
 682                 } else {
 683                         samehost_burst -= mesh->loop.now.tv_sec - samehost_burst_time;
 684                 }
 685
 686                 samehost_burst_time = mesh->loop.now.tv_sec;
 687                 samehost_burst++;
 688
 689                 if(samehost_burst > max_connection_burst) {
 690                         tarpit = fd;
 691                         return;
 692                 }
 693         }
 694
 695         memcpy(&prev_sa, &sa, sizeof(sa));
 696
 697         // Check if we get many connections from different hosts
 698
 699         static int connection_burst;
 700         static int connection_burst_time;
 701
 702         if(mesh->loop.now.tv_sec - connection_burst_time > connection_burst) {
 703                 connection_burst = 0;
 704         } else {
 705                 connection_burst -= mesh->loop.now.tv_sec - connection_burst_time;
 706         }
 707
 708         connection_burst_time = mesh->loop.now.tv_sec;
 709         connection_burst++;
 710
 711         if(connection_burst >= max_connection_burst) {
 712                 connection_burst = max_connection_burst;
 713                 tarpit = fd;
 714                 return;
 715         }
 716
 717         // Accept the new connection
 718
 719         c = new_connection();
 720         c->name = xstrdup("<unknown>");
 721         c->outcompression = mesh->self->connection->outcompression;
 722
 723         c->address = sa;
 724         c->socket = fd;
 725         c->last_ping_time = mesh->loop.now.tv_sec;
 726
 727         char *hostname = sockaddr2hostname(&sa);
 728         logger(mesh, MESHLINK_INFO, "Connection from %s", hostname);
 729         free(hostname);
 730
 731         io_add(&mesh->loop, &c->io, handle_meta_io, c, c->socket, IO_READ);
 732
 733         configure_tcp(c);
 734
 735         connection_add(mesh, c);
 736
 737         c->allow_request = ID;
 738         send_id(mesh, c);
 739 }
 740
 741 static void free_outgoing(outgoing_t *outgoing) {
 742         meshlink_handle_t *mesh = outgoing->mesh;
 743
 744         timeout_del(&mesh->loop, &outgoing->ev);
 745
 746         if(outgoing->ai) {
 747                 if(outgoing->state == OUTGOING_KNOWN) {
 748                         free_known_addresses(outgoing->ai);
 749                 } else {
 750                         freeaddrinfo(outgoing->ai);
 751                 }
 752         }
 753
 754         if(outgoing->config_tree) {
 755                 exit_configuration(&outgoing->config_tree);
 756         }
 757
 758         if(outgoing->name) {
 759                 free(outgoing->name);
 760         }
 761
 762         free(outgoing);
 763 }
 764
 765 void try_outgoing_connections(meshlink_handle_t *mesh) {
 766         /* If there is no outgoing list yet, create one. Otherwise, mark all outgoings as deleted. */
 767
 768         if(!mesh->outgoings) {
 769                 mesh->outgoings = list_alloc((list_action_t)free_outgoing);
 770         } else {
 771                 for list_each(outgoing_t, outgoing, mesh->outgoings) {
 772                         outgoing->timeout = -1;
 773                 }
 774         }
 775
 776         /* Make sure there is one outgoing_t in the list for each ConnectTo. */
 777
 778         // TODO: Drop support for ConnectTo since AutoConnect is now always on?
 779         for(config_t *cfg = lookup_config(mesh->config, "ConnectTo"); cfg; cfg = lookup_config_next(mesh->config, cfg)) {
 780                 char *name;
 781                 get_config_string(cfg, &name);
 782
 783                 if(!check_id(name)) {
 784                         logger(mesh, MESHLINK_ERROR,
 785                                "Invalid name for outgoing connection in line %d",
 786                                cfg->line);
 787                         free(name);
 788                         continue;
 789                 }
 790
 791                 bool found = false;
 792
 793                 for list_each(outgoing_t, outgoing, mesh->outgoings) {
 794                         if(!strcmp(outgoing->name, name)) {
 795                                 found = true;
 796                                 outgoing->timeout = 0;
 797                                 break;
 798                         }
 799                 }
 800
 801                 if(!found) {
 802                         outgoing_t *outgoing = xzalloc(sizeof(*outgoing));
 803                         outgoing->mesh = mesh;
 804                         outgoing->name = name;
 805                         list_insert_tail(mesh->outgoings, outgoing);
 806                         setup_outgoing_connection(mesh, outgoing);
 807                 }
 808         }
 809
 810         /* Terminate any connections whose outgoing_t is to be deleted. */
 811
 812         for list_each(connection_t, c, mesh->connections) {
 813                 if(c->outgoing && c->outgoing->timeout == -1) {
 814                         c->outgoing = NULL;
 815                         logger(mesh, MESHLINK_INFO, "No more outgoing connection to %s", c->name);
 816                         terminate_connection(mesh, c, c->status.active);
 817                 }
 818         }
 819
 820         /* Delete outgoing_ts for which there is no ConnectTo. */
 821
 822         for list_each(outgoing_t, outgoing, mesh->outgoings)
 823                 if(outgoing->timeout == -1) {
 824                         list_delete_node(mesh->outgoings, node);
 825                 }
 826 }