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

   1 /*
   2     net_socket.c -- Handle various kinds of sockets.
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2013 Guus Sliepen <guus@tinc-vpn.org>
   5                   2006      Scott Lamb <slamb@slamb.org>
   6                   2009      Florian Forster <octo@verplant.org>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License along
  19     with this program; if not, write to the Free Software Foundation, Inc.,
  20     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21 */
  22
  23 #include "system.h"
  24
  25 #include "conf.h"
  26 #include "connection.h"
  27 #include "control_common.h"
  28 #include "list.h"
  29 #include "logger.h"
  30 #include "meta.h"
  31 #include "names.h"
  32 #include "net.h"
  33 #include "netutl.h"
  34 #include "protocol.h"
  35 #include "utils.h"
  36 #include "xalloc.h"
  37
  38 /* Needed on Mac OS/X */
  39 #ifndef SOL_TCP
  40 #define SOL_TCP IPPROTO_TCP
  41 #endif
  42
  43 int addressfamily = AF_UNSPEC;
  44 int maxtimeout = 900;
  45 int seconds_till_retry = 5;
  46 int udp_rcvbuf = 0;
  47 int udp_sndbuf = 0;
  48 int max_connection_burst = 100;
  49
  50 listen_socket_t listen_socket[MAXSOCKETS];
  51 int listen_sockets;
  52 #ifndef HAVE_MINGW
  53 io_t unix_socket;
  54 #endif
  55 list_t *outgoing_list = NULL;
  56
  57 /* Setup sockets */
  58
  59 static void configure_tcp(connection_t *c) {
  60         int option;
  61
  62 #ifdef O_NONBLOCK
  63         int flags = fcntl(c->socket, F_GETFL);
  64
  65         if(fcntl(c->socket, F_SETFL, flags | O_NONBLOCK) < 0) {
  66                 logger(DEBUG_ALWAYS, LOG_ERR, "fcntl for %s: %s", c->hostname, strerror(errno));
  67         }
  68 #elif defined(WIN32)
  69         unsigned long arg = 1;
  70
  71         if(ioctlsocket(c->socket, FIONBIO, &arg) != 0) {
  72                 logger(DEBUG_ALWAYS, LOG_ERR, "ioctlsocket for %s: %s", c->hostname, sockstrerror(sockerrno));
  73         }
  74 #endif
  75
  76 #if defined(SOL_TCP) && defined(TCP_NODELAY)
  77         option = 1;
  78         setsockopt(c->socket, SOL_TCP, TCP_NODELAY, (void *)&option, sizeof option);
  79 #endif
  80
  81 #if defined(SOL_IP) && defined(IP_TOS) && defined(IPTOS_LOWDELAY)
  82         option = IPTOS_LOWDELAY;
  83         setsockopt(c->socket, SOL_IP, IP_TOS, (void *)&option, sizeof option);
  84 #endif
  85 }
  86
  87 static bool bind_to_interface(int sd) {
  88         char *iface;
  89
  90 #if defined(SOL_SOCKET) && defined(SO_BINDTODEVICE)
  91         struct ifreq ifr;
  92         int status;
  93 #endif /* defined(SOL_SOCKET) && defined(SO_BINDTODEVICE) */
  94
  95         if(!get_config_string (lookup_config (config_tree, "BindToInterface"), &iface))
  96                 return true;
  97
  98 #if defined(SOL_SOCKET) && defined(SO_BINDTODEVICE)
  99         memset(&ifr, 0, sizeof(ifr));
 100         strncpy(ifr.ifr_ifrn.ifrn_name, iface, IFNAMSIZ);
 101         ifr.ifr_ifrn.ifrn_name[IFNAMSIZ - 1] = 0;
 102
 103         status = setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(ifr));
 104         if(status) {
 105                 logger(DEBUG_ALWAYS, LOG_ERR, "Can't bind to interface %s: %s", iface,
 106                                 strerror(errno));
 107                 return false;
 108         }
 109 #else /* if !defined(SOL_SOCKET) || !defined(SO_BINDTODEVICE) */
 110         logger(DEBUG_ALWAYS, LOG_WARNING, "%s not supported on this platform", "BindToInterface");
 111 #endif
 112
 113         return true;
 114 }
 115
 116 static bool bind_to_address(connection_t *c) {
 117         int s = -1;
 118
 119         for(int i = 0; i < listen_sockets; i++) {
 120                 if(listen_socket[i].sa.sa.sa_family != c->address.sa.sa_family)
 121                         continue;
 122                 if(s >= 0)
 123                         return false;
 124                 s = i;
 125         }
 126
 127         if(s < 0)
 128                 return false;
 129
 130         sockaddr_t sa = listen_socket[s].sa;
 131         if(sa.sa.sa_family == AF_INET)
 132                 sa.in.sin_port = 0;
 133         else if(sa.sa.sa_family == AF_INET6)
 134                 sa.in6.sin6_port = 0;
 135
 136         if(bind(c->socket, &sa.sa, SALEN(sa.sa))) {
 137                 logger(DEBUG_CONNECTIONS, LOG_WARNING, "Can't bind outgoing socket: %s", strerror(errno));
 138                 return false;
 139         }
 140
 141         return true;
 142 }
 143
 144 int setup_listen_socket(const sockaddr_t *sa) {
 145         int nfd;
 146         char *addrstr;
 147         int option;
 148         char *iface;
 149
 150         nfd = socket(sa->sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 151
 152         if(nfd < 0) {
 153                 logger(DEBUG_STATUS, LOG_ERR, "Creating metasocket failed: %s", sockstrerror(sockerrno));
 154                 return -1;
 155         }
 156
 157 #ifdef FD_CLOEXEC
 158         fcntl(nfd, F_SETFD, FD_CLOEXEC);
 159 #endif
 160
 161         /* Optimize TCP settings */
 162
 163         option = 1;
 164         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof option);
 165
 166 #if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
 167         if(sa->sa.sa_family == AF_INET6)
 168                 setsockopt(nfd, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 169 #endif
 170
 171         if(get_config_string
 172            (lookup_config(config_tree, "BindToInterface"), &iface)) {
 173 #if defined(SOL_SOCKET) && defined(SO_BINDTODEVICE)
 174                 struct ifreq ifr;
 175
 176                 memset(&ifr, 0, sizeof ifr);
 177                 strncpy(ifr.ifr_ifrn.ifrn_name, iface, IFNAMSIZ);
 178
 179                 if(setsockopt(nfd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof ifr)) {
 180                         closesocket(nfd);
 181                         logger(DEBUG_ALWAYS, LOG_ERR, "Can't bind to interface %s: %s", iface,
 182                                    strerror(sockerrno));
 183                         return -1;
 184                 }
 185 #else
 186                 logger(DEBUG_ALWAYS, LOG_WARNING, "%s not supported on this platform", "BindToInterface");
 187 #endif
 188         }
 189
 190         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
 191                 closesocket(nfd);
 192                 addrstr = sockaddr2hostname(sa);
 193                 logger(DEBUG_ALWAYS, LOG_ERR, "Can't bind to %s/tcp: %s", addrstr, sockstrerror(sockerrno));
 194                 free(addrstr);
 195                 return -1;
 196         }
 197
 198         if(listen(nfd, 3)) {
 199                 closesocket(nfd);
 200                 logger(DEBUG_ALWAYS, LOG_ERR, "System call `%s' failed: %s", "listen", sockstrerror(sockerrno));
 201                 return -1;
 202         }
 203
 204         return nfd;
 205 }
 206
 207 int setup_vpn_in_socket(const sockaddr_t *sa) {
 208         int nfd;
 209         char *addrstr;
 210         int option;
 211
 212         nfd = socket(sa->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
 213
 214         if(nfd < 0) {
 215                 logger(DEBUG_ALWAYS, LOG_ERR, "Creating UDP socket failed: %s", sockstrerror(sockerrno));
 216                 return -1;
 217         }
 218
 219 #ifdef FD_CLOEXEC
 220         fcntl(nfd, F_SETFD, FD_CLOEXEC);
 221 #endif
 222
 223 #ifdef O_NONBLOCK
 224         {
 225                 int flags = fcntl(nfd, F_GETFL);
 226
 227                 if(fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0) {
 228                         closesocket(nfd);
 229                         logger(DEBUG_ALWAYS, LOG_ERR, "System call `%s' failed: %s", "fcntl",
 230                                    strerror(errno));
 231                         return -1;
 232                 }
 233         }
 234 #elif defined(WIN32)
 235         {
 236                 unsigned long arg = 1;
 237                 if(ioctlsocket(nfd, FIONBIO, &arg) != 0) {
 238                         closesocket(nfd);
 239                         logger(DEBUG_ALWAYS, LOG_ERR, "Call to `%s' failed: %s", "ioctlsocket", sockstrerror(sockerrno));
 240                         return -1;
 241                 }
 242         }
 243 #endif
 244
 245         option = 1;
 246         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof option);
 247         setsockopt(nfd, SOL_SOCKET, SO_BROADCAST, (void *)&option, sizeof option);
 248
 249         if(udp_rcvbuf && setsockopt(nfd, SOL_SOCKET, SO_RCVBUF, (void *)&udp_rcvbuf, sizeof(udp_rcvbuf)))
 250                 logger(DEBUG_ALWAYS, LOG_WARNING, "Can't set UDP SO_RCVBUF to %i: %s", udp_rcvbuf, strerror(errno));
 251
 252         if(udp_sndbuf && setsockopt(nfd, SOL_SOCKET, SO_SNDBUF, (void *)&udp_sndbuf, sizeof(udp_sndbuf)))
 253                 logger(DEBUG_ALWAYS, LOG_WARNING, "Can't set UDP SO_SNDBUF to %i: %s", udp_sndbuf, strerror(errno));
 254
 255 #if defined(IPPROTO_IPV6) && defined(IPV6_V6ONLY)
 256         if(sa->sa.sa_family == AF_INET6)
 257                 setsockopt(nfd, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 258 #endif
 259
 260 #if defined(IP_DONTFRAG) && !defined(IP_DONTFRAGMENT)
 261 #define IP_DONTFRAGMENT IP_DONTFRAG
 262 #endif
 263
 264 #if defined(SOL_IP) && defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DO)
 265         if(myself->options & OPTION_PMTU_DISCOVERY) {
 266                 option = IP_PMTUDISC_DO;
 267                 setsockopt(nfd, SOL_IP, IP_MTU_DISCOVER, (void *)&option, sizeof(option));
 268         }
 269 #elif defined(IPPROTO_IP) && defined(IP_DONTFRAGMENT)
 270         if(myself->options & OPTION_PMTU_DISCOVERY) {
 271                 option = 1;
 272                 setsockopt(nfd, IPPROTO_IP, IP_DONTFRAGMENT, (void *)&option, sizeof(option));
 273         }
 274 #else
 275 #warning No way to disable IPv4 fragmentation
 276 #endif
 277
 278 #if defined(SOL_IPV6) && defined(IPV6_MTU_DISCOVER) && defined(IPV6_PMTUDISC_DO)
 279         if(myself->options & OPTION_PMTU_DISCOVERY) {
 280                 option = IPV6_PMTUDISC_DO;
 281                 setsockopt(nfd, SOL_IPV6, IPV6_MTU_DISCOVER, (void *)&option, sizeof(option));
 282         }
 283 #elif defined(IPPROTO_IPV6) && defined(IPV6_DONTFRAG)
 284         if(myself->options & OPTION_PMTU_DISCOVERY) {
 285                 option = 1;
 286                 setsockopt(nfd, IPPROTO_IPV6, IPV6_DONTFRAG, (void *)&option, sizeof(option));
 287         }
 288 #else
 289 #warning No way to disable IPv6 fragmentation
 290 #endif
 291
 292         if (!bind_to_interface(nfd)) {
 293                 closesocket(nfd);
 294                 return -1;
 295         }
 296
 297         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
 298                 closesocket(nfd);
 299                 addrstr = sockaddr2hostname(sa);
 300                 logger(DEBUG_ALWAYS, LOG_ERR, "Can't bind to %s/udp: %s", addrstr, sockstrerror(sockerrno));
 301                 free(addrstr);
 302                 return -1;
 303         }
 304
 305         return nfd;
 306 } /* int setup_vpn_in_socket */
 307
 308 static void retry_outgoing_handler(void *data) {
 309         setup_outgoing_connection(data);
 310 }
 311
 312 void retry_outgoing(outgoing_t *outgoing) {
 313         outgoing->timeout += 5;
 314
 315         if(outgoing->timeout > maxtimeout)
 316                 outgoing->timeout = maxtimeout;
 317
 318         timeout_add(&outgoing->ev, retry_outgoing_handler, outgoing, &(struct timeval){outgoing->timeout, rand() % 100000});
 319
 320         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Trying to re-establish outgoing connection in %d seconds", outgoing->timeout);
 321 }
 322
 323 void finish_connecting(connection_t *c) {
 324         logger(DEBUG_CONNECTIONS, LOG_INFO, "Connected to %s (%s)", c->name, c->hostname);
 325
 326         c->last_ping_time = now.tv_sec;
 327         c->status.connecting = false;
 328
 329         send_id(c);
 330 }
 331
 332 static void do_outgoing_pipe(connection_t *c, char *command) {
 333 #ifndef HAVE_MINGW
 334         int fd[2];
 335
 336         if(socketpair(AF_UNIX, SOCK_STREAM, 0, fd)) {
 337                 logger(DEBUG_ALWAYS, LOG_ERR, "Could not create socketpair: %s", strerror(errno));
 338                 return;
 339         }
 340
 341         if(fork()) {
 342                 c->socket = fd[0];
 343                 close(fd[1]);
 344                 logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Using proxy %s", command);
 345                 return;
 346         }
 347
 348         close(0);
 349         close(1);
 350         close(fd[0]);
 351         dup2(fd[1], 0);
 352         dup2(fd[1], 1);
 353         close(fd[1]);
 354
 355         // Other filedescriptors should be closed automatically by CLOEXEC
 356
 357         char *host = NULL;
 358         char *port = NULL;
 359
 360         sockaddr2str(&c->address, &host, &port);
 361         setenv("REMOTEADDRESS", host, true);
 362         setenv("REMOTEPORT", port, true);
 363         setenv("NODE", c->name, true);
 364         setenv("NAME", myself->name, true);
 365         if(netname)
 366                 setenv("NETNAME", netname, true);
 367
 368         int result = system(command);
 369         if(result < 0)
 370                 logger(DEBUG_ALWAYS, LOG_ERR, "Could not execute %s: %s", command, strerror(errno));
 371         else if(result)
 372                 logger(DEBUG_ALWAYS, LOG_ERR, "%s exited with non-zero status %d", command, result);
 373         exit(result);
 374 #else
 375         logger(DEBUG_ALWAYS, LOG_ERR, "Proxy type exec not supported on this platform!");
 376         return;
 377 #endif
 378 }
 379
 380 static void handle_meta_write(connection_t *c) {
 381         if(c->outbuf.len <= c->outbuf.offset)
 382                 return;
 383
 384         ssize_t outlen = send(c->socket, c->outbuf.data + c->outbuf.offset, c->outbuf.len - c->outbuf.offset, 0);
 385         if(outlen <= 0) {
 386                 if(!errno || errno == EPIPE) {
 387                         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Connection closed by %s (%s)", c->name, c->hostname);
 388                 } else if(sockwouldblock(sockerrno)) {
 389                         logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Sending %d bytes to %s (%s) would block", c->outbuf.len - c->outbuf.offset, c->name, c->hostname);
 390                         return;
 391                 } else {
 392                         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));
 393                 }
 394
 395                 terminate_connection(c, c->status.active);
 396                 return;
 397         }
 398
 399         buffer_read(&c->outbuf, outlen);
 400         if(!c->outbuf.len)
 401                 io_set(&c->io, IO_READ);
 402 }
 403
 404 static void handle_meta_io(void *data, int flags) {
 405         connection_t *c = data;
 406
 407         if(c->status.connecting) {
 408                 c->status.connecting = false;
 409
 410                 int result;
 411                 socklen_t len = sizeof result;
 412                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 413
 414                 if(!result)
 415                         finish_connecting(c);
 416                 else {
 417                         logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Error while connecting to %s (%s): %s", c->name, c->hostname, sockstrerror(result));
 418                         terminate_connection(c, false);
 419                         return;
 420                 }
 421         }
 422
 423         if(flags & IO_WRITE)
 424                 handle_meta_write(c);
 425         else
 426                 handle_meta_connection_data(c);
 427 }
 428
 429 bool do_outgoing_connection(outgoing_t *outgoing) {
 430         char *address, *port, *space;
 431         struct addrinfo *proxyai = NULL;
 432         int result;
 433
 434 begin:
 435         if(!outgoing->ai) {
 436                 if(!outgoing->cfg) {
 437                         logger(DEBUG_CONNECTIONS, LOG_ERR, "Could not set up a meta connection to %s", outgoing->name);
 438                         retry_outgoing(outgoing);
 439                         return false;
 440                 }
 441
 442                 get_config_string(outgoing->cfg, &address);
 443
 444                 space = strchr(address, ' ');
 445                 if(space) {
 446                         port = xstrdup(space + 1);
 447                         *space = 0;
 448                 } else {
 449                         if(!get_config_string(lookup_config(outgoing->config_tree, "Port"), &port))
 450                                 port = xstrdup("655");
 451                 }
 452
 453                 outgoing->ai = str2addrinfo(address, port, SOCK_STREAM);
 454                 free(address);
 455                 free(port);
 456
 457                 outgoing->aip = outgoing->ai;
 458                 outgoing->cfg = lookup_config_next(outgoing->config_tree, outgoing->cfg);
 459         }
 460
 461         if(!outgoing->aip) {
 462                 if(outgoing->ai)
 463                         freeaddrinfo(outgoing->ai);
 464                 outgoing->ai = NULL;
 465                 goto begin;
 466         }
 467
 468         connection_t *c = new_connection();
 469         c->outgoing = outgoing;
 470
 471         memcpy(&c->address, outgoing->aip->ai_addr, outgoing->aip->ai_addrlen);
 472         outgoing->aip = outgoing->aip->ai_next;
 473
 474         c->hostname = sockaddr2hostname(&c->address);
 475
 476         logger(DEBUG_CONNECTIONS, LOG_INFO, "Trying to connect to %s (%s)", outgoing->name, c->hostname);
 477
 478         if(!proxytype) {
 479                 c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 480                 configure_tcp(c);
 481         } else if(proxytype == PROXY_EXEC) {
 482                 do_outgoing_pipe(c, proxyhost);
 483         } else {
 484                 proxyai = str2addrinfo(proxyhost, proxyport, SOCK_STREAM);
 485                 if(!proxyai) {
 486                         free_connection(c);
 487                         goto begin;
 488                 }
 489                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Using proxy at %s port %s", proxyhost, proxyport);
 490                 c->socket = socket(proxyai->ai_family, SOCK_STREAM, IPPROTO_TCP);
 491                 configure_tcp(c);
 492         }
 493
 494         if(c->socket == -1) {
 495                 logger(DEBUG_CONNECTIONS, LOG_ERR, "Creating socket for %s failed: %s", c->hostname, sockstrerror(sockerrno));
 496                 free_connection(c);
 497                 goto begin;
 498         }
 499
 500 #ifdef FD_CLOEXEC
 501         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
 502 #endif
 503
 504         if(proxytype != PROXY_EXEC) {
 505 #if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
 506                 int option = 1;
 507                 if(c->address.sa.sa_family == AF_INET6)
 508                         setsockopt(c->socket, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 509 #endif
 510
 511                 bind_to_interface(c->socket);
 512                 bind_to_address(c);
 513         }
 514
 515         /* Connect */
 516
 517         if(!proxytype) {
 518                 result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
 519         } else if(proxytype == PROXY_EXEC) {
 520                 result = 0;
 521         } else {
 522                 result = connect(c->socket, proxyai->ai_addr, proxyai->ai_addrlen);
 523                 freeaddrinfo(proxyai);
 524         }
 525
 526         if(result == -1 && !sockinprogress(sockerrno)) {
 527                 logger(DEBUG_CONNECTIONS, LOG_ERR, "Could not connect to %s (%s): %s", outgoing->name, c->hostname, sockstrerror(sockerrno));
 528                 free_connection(c);
 529
 530                 goto begin;
 531         }
 532
 533         /* Now that there is a working socket, fill in the rest and register this connection. */
 534
 535         c->status.connecting = true;
 536         c->name = xstrdup(outgoing->name);
 537         c->outcipher = myself->connection->outcipher;
 538         c->outdigest = myself->connection->outdigest;
 539         c->outmaclength = myself->connection->outmaclength;
 540         c->outcompression = myself->connection->outcompression;
 541         c->last_ping_time = now.tv_sec;
 542
 543         connection_add(c);
 544
 545         io_add(&c->io, handle_meta_io, c, c->socket, IO_READ|IO_WRITE);
 546
 547         return true;
 548 }
 549
 550 void setup_outgoing_connection(outgoing_t *outgoing) {
 551         timeout_del(&outgoing->ev);
 552
 553         node_t *n = lookup_node(outgoing->name);
 554
 555         if(n && n->connection) {
 556                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Already connected to %s", outgoing->name);
 557
 558                 n->connection->outgoing = outgoing;
 559                 return;
 560         }
 561
 562         init_configuration(&outgoing->config_tree);
 563         read_host_config(outgoing->config_tree, outgoing->name);
 564         outgoing->cfg = lookup_config(outgoing->config_tree, "Address");
 565
 566         if(!outgoing->cfg) {
 567                 logger(DEBUG_ALWAYS, LOG_ERR, "No address specified for %s", outgoing->name);
 568                 return;
 569         }
 570
 571         do_outgoing_connection(outgoing);
 572 }
 573
 574 /*
 575   accept a new tcp connect and create a
 576   new connection
 577 */
 578 void handle_new_meta_connection(void *data, int flags) {
 579         listen_socket_t *l = data;
 580         connection_t *c;
 581         sockaddr_t sa;
 582         int fd;
 583         socklen_t len = sizeof sa;
 584
 585         fd = accept(l->tcp.fd, &sa.sa, &len);
 586
 587         if(fd < 0) {
 588                 logger(DEBUG_ALWAYS, LOG_ERR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 589                 return;
 590         }
 591
 592         sockaddrunmap(&sa);
 593
 594         // Check if we get many connections from the same host
 595
 596         static sockaddr_t prev_sa;
 597         static int tarpit = -1;
 598
 599         if(tarpit >= 0) {
 600                 closesocket(tarpit);
 601                 tarpit = -1;
 602         }
 603
 604         if(!sockaddrcmp_noport(&sa, &prev_sa)) {
 605                 static int samehost_burst;
 606                 static int samehost_burst_time;
 607
 608                 if(now.tv_sec - samehost_burst_time > samehost_burst)
 609                         samehost_burst = 0;
 610                 else
 611                         samehost_burst -= now.tv_sec - samehost_burst_time;
 612
 613                 samehost_burst_time = now.tv_sec;
 614                 samehost_burst++;
 615
 616                 if(samehost_burst > max_connection_burst) {
 617                         tarpit = fd;
 618                         return;
 619                 }
 620         }
 621
 622         memcpy(&prev_sa, &sa, sizeof sa);
 623
 624         // Check if we get many connections from different hosts
 625
 626         static int connection_burst;
 627         static int connection_burst_time;
 628
 629         if(now.tv_sec - connection_burst_time > connection_burst)
 630                 connection_burst = 0;
 631         else
 632                 connection_burst -= now.tv_sec - connection_burst_time;
 633
 634         connection_burst_time = now.tv_sec;
 635         connection_burst++;
 636
 637         if(connection_burst >= max_connection_burst) {
 638                 connection_burst = max_connection_burst;
 639                 tarpit = fd;
 640                 return;
 641         }
 642
 643         // Accept the new connection
 644
 645         c = new_connection();
 646         c->name = xstrdup("<unknown>");
 647         c->outcipher = myself->connection->outcipher;
 648         c->outdigest = myself->connection->outdigest;
 649         c->outmaclength = myself->connection->outmaclength;
 650         c->outcompression = myself->connection->outcompression;
 651
 652         c->address = sa;
 653         c->hostname = sockaddr2hostname(&sa);
 654         c->socket = fd;
 655         c->last_ping_time = now.tv_sec;
 656
 657         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Connection from %s", c->hostname);
 658
 659         io_add(&c->io, handle_meta_io, c, c->socket, IO_READ);
 660
 661         configure_tcp(c);
 662
 663         connection_add(c);
 664
 665         c->allow_request = ID;
 666         send_id(c);
 667 }
 668
 669 #ifndef HAVE_MINGW
 670 /*
 671   accept a new UNIX socket connection
 672 */
 673 void handle_new_unix_connection(void *data, int flags) {
 674         io_t *io = data;
 675         connection_t *c;
 676         sockaddr_t sa;
 677         int fd;
 678         socklen_t len = sizeof sa;
 679
 680         fd = accept(io->fd, &sa.sa, &len);
 681
 682         if(fd < 0) {
 683                 logger(DEBUG_ALWAYS, LOG_ERR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 684                 return;
 685         }
 686
 687         sockaddrunmap(&sa);
 688
 689         c = new_connection();
 690         c->name = xstrdup("<control>");
 691         c->address = sa;
 692         c->hostname = xstrdup("localhost port unix");
 693         c->socket = fd;
 694         c->last_ping_time = now.tv_sec;
 695
 696         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Connection from %s", c->hostname);
 697
 698         io_add(&c->io, handle_meta_io, c, c->socket, IO_READ);
 699
 700         connection_add(c);
 701
 702         c->allow_request = ID;
 703
 704         send_id(c);
 705 }
 706 #endif
 707
 708 static void free_outgoing(outgoing_t *outgoing) {
 709         timeout_del(&outgoing->ev);
 710
 711         if(outgoing->ai)
 712                 freeaddrinfo(outgoing->ai);
 713
 714         if(outgoing->config_tree)
 715                 exit_configuration(&outgoing->config_tree);
 716
 717         if(outgoing->name)
 718                 free(outgoing->name);
 719
 720         free(outgoing);
 721 }
 722
 723 void try_outgoing_connections(void) {
 724         /* If there is no outgoing list yet, create one. Otherwise, mark all outgoings as deleted. */
 725
 726         if(!outgoing_list) {
 727                 outgoing_list = list_alloc((list_action_t)free_outgoing);
 728         } else {
 729                 for list_each(outgoing_t, outgoing, outgoing_list)
 730                         outgoing->timeout = -1;
 731         }
 732
 733         /* Make sure there is one outgoing_t in the list for each ConnectTo. */
 734
 735         for(config_t *cfg = lookup_config(config_tree, "ConnectTo"); cfg; cfg = lookup_config_next(config_tree, cfg)) {
 736                 char *name;
 737                 get_config_string(cfg, &name);
 738
 739                 if(!check_id(name)) {
 740                         logger(DEBUG_ALWAYS, LOG_ERR,
 741                                    "Invalid name for outgoing connection in %s line %d",
 742                                    cfg->file, cfg->line);
 743                         free(name);
 744                         continue;
 745                 }
 746
 747                 bool found = false;
 748
 749                 for list_each(outgoing_t, outgoing, outgoing_list) {
 750                         if(!strcmp(outgoing->name, name)) {
 751                                 found = true;
 752                                 outgoing->timeout = 0;
 753                                 break;
 754                         }
 755                 }
 756
 757                 if(!found) {
 758                         outgoing_t *outgoing = xzalloc(sizeof *outgoing);
 759                         outgoing->name = name;
 760                         list_insert_tail(outgoing_list, outgoing);
 761                         setup_outgoing_connection(outgoing);
 762                 }
 763         }
 764
 765         /* Terminate any connections whose outgoing_t is to be deleted. */
 766
 767         for list_each(connection_t, c, connection_list) {
 768                 if(c->outgoing && c->outgoing->timeout == -1) {
 769                         c->outgoing = NULL;
 770                         logger(DEBUG_CONNECTIONS, LOG_INFO, "No more outgoing connection to %s", c->name);
 771                         terminate_connection(c, c->status.active);
 772                 }
 773         }
 774
 775         /* Delete outgoing_ts for which there is no ConnectTo. */
 776
 777         for list_each(outgoing_t, outgoing, outgoing_list)
 778                 if(outgoing->timeout == -1)
 779                         list_delete_node(outgoing_list, node);
 780 }