src/curvetun.c

   1 /*
   2  * curvetun - the cipherspace wormhole creator
   3  * Part of the netsniff-ng project
   4  * By Daniel Borkmann <daniel@netsniff-ng.org>
   5  * Copyright 2011 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,
   6  * Copyright 2011 Emmanuel Roullit.
   7  * Subject to the GPL, version 2.
   8  *
   9  * This is curvetun, a lightweight, high-speed ECDH multiuser IP tunnel for
  10  * Linux that is based on epoll(2). curvetun uses the Linux TUN/TAP interface
  11  * and supports {IPv4,IPv6} over {IPv4,IPv6} with UDP or TCP as carrier
  12  * protocols. It has an integrated packet forwarding trie, thus multiple
  13  * users with different IPs can be handled via a single tunnel device on the
  14  * server side and flows are scheduled for processing in a CPU-local manner.
  15  * For transmission, packets are being compressed and encrypted by both, the
  16  * client and the server side. As an appropriate key management, public-key
  17  * cryptography based on elliptic curves are being used and packets are
  18  * encrypted by a symmetric stream cipher (Salsa20) and authenticated by a MAC
  19  * (Poly1305), where keys have previously been computed with the ECDH key
  20  * agreement protocol (Curve25519). Cryptography is based on Daniel J.
  21  * Bernsteins Networking and Cryptography library (NaCl).
  22  *
  23  *   He used often to say there was only one Road; that it was like a great
  24  *   river: it's springs were at every doorstep and every path was it's
  25  *   tributary. "It's a dangerous business, Frodo, going out of your door,"
  26  *   he used to say. "You step into the Road, and if you don't keep your
  27  *   feet, there is no telling where you might be swept off to."
  28  *
  29  *     -- The Lord of the Rings, Frodo about his uncle Bilbo Baggins,
  30  *        Chapter 'Three is Company'.
  31  */
  32
  33 #define _GNU_SOURCE
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <fcntl.h>
  37 #include <string.h>
  38 #include <ctype.h>
  39 #include <getopt.h>
  40 #include <errno.h>
  41 #include <stdbool.h>
  42 #include <limits.h>
  43 #include <sys/types.h>
  44 #include <sys/stat.h>
  45 #include <sys/socket.h>
  46 #include <sys/ptrace.h>
  47 #include <netinet/in.h>
  48 #include <unistd.h>
  49 #include <signal.h>
  50
  51 #include "xutils.h"
  52 #include "die.h"
  53 #include "xmalloc.h"
  54 #include "curvetun.h"
  55 #include "curve.h"
  56 #include "ct_usermgmt.h"
  57 #include "ct_servmgmt.h"
  58 #include "xio.h"
  59 #include "tprintf.h"
  60 #include "crypto_verify_32.h"
  61 #include "crypto_box_curve25519xsalsa20poly1305.h"
  62 #include "crypto_scalarmult_curve25519.h"
  63 #include "crypto_auth_hmacsha512256.h"
  64
  65 #define CURVETUN_ENTROPY_SOURCE "/dev/random"
  66
  67 extern void print_stun_probe(char *server, uint16_t sport, uint16_t tunport);
  68
  69 enum working_mode {
  70         MODE_UNKNOW,
  71         MODE_KEYGEN,
  72         MODE_EXPORT,
  73         MODE_DUMPC,
  74         MODE_DUMPS,
  75         MODE_CLIENT,
  76         MODE_SERVER,
  77 };
  78
  79 volatile sig_atomic_t sigint = 0;
  80
  81 static const char *short_options = "kxc::svhp:t:d:uCS46DN";
  82 static const struct option long_options[] = {
  83         {"client",      optional_argument,      NULL, 'c'},
  84         {"dev",         required_argument,      NULL, 'd'},
  85         {"port",        required_argument,      NULL, 'p'},
  86         {"stun",        required_argument,      NULL, 't'},
  87         {"keygen",      no_argument,            NULL, 'k'},
  88         {"export",      no_argument,            NULL, 'x'},
  89         {"dumpc",       no_argument,            NULL, 'C'},
  90         {"dumps",       no_argument,            NULL, 'S'},
  91         {"no-logging",  no_argument,            NULL, 'N'},
  92         {"server",      no_argument,            NULL, 's'},
  93         {"udp",         no_argument,            NULL, 'u'},
  94         {"ipv4",        no_argument,            NULL, '4'},
  95         {"ipv6",        no_argument,            NULL, '6'},
  96         {"nofork",      no_argument,            NULL, 'D'},
  97         {"version",     no_argument,            NULL, 'v'},
  98         {"help",        no_argument,            NULL, 'h'},
  99         {NULL, 0, NULL, 0}
 100 };
 101
 102 static void signal_handler(int number)
 103 {
 104         switch (number) {
 105         case SIGINT:
 106                 sigint = 1;
 107                 break;
 108         default:
 109                 break;
 110         }
 111 }
 112
 113 static void header(void)
 114 {
 115         printf("%s%s%s\n", colorize_start(bold), "curvetun "
 116                VERSION_STRING, colorize_end());
 117 }
 118
 119 static void help(void)
 120 {
 121         printf("\ncurvetun %s, lightweight curve25519-based VPN/IP tunnel\n",
 122                VERSION_STRING);
 123         puts("http://www.netsniff-ng.org\n\n"
 124              "Usage: curvetun [options]\n"
 125              "Options, general:\n"
 126              "  -k|--keygen             Generate public/private keypair\n"
 127              "  -x|--export             Export your public data for remote servers\n"
 128              "  -C|--dumpc              Dump parsed clients\n"
 129              "  -S|--dumps              Dump parsed servers\n"
 130              "  -D|--nofork             Do not daemonize\n"
 131              "  -d|--dev <tun>          Networking tunnel device, e.g. tun0\n"
 132              "  -v|--version            Print version\n"
 133              "  -h|--help               Print this help\n"
 134              "  -c|--client[=alias]     Client mode, server alias optional\n"
 135              "  -s|--server             Server mode, options follow below\n"
 136              "  -N|--no-logging         Disable server logging (for better anonymity)\n"
 137              "  -p|--port <num>         Server port number (mandatory)\n"
 138              "  -t|--stun <server>      Show public IP/Port mapping via STUN\n"
 139              "  -u|--udp                Use UDP as carrier instead of TCP\n"
 140              "  -4|--ipv4               Tunnel devices are IPv4\n"
 141              "  -6|--ipv6               Tunnel devices are IPv6\n"
 142              "                          (default: same as carrier protocol)\n\n"
 143              "Example:\n"
 144              "  See Documentation/Curvetun for a configuration example.\n"
 145              "  curvetun --keygen\n"
 146              "  curvetun --export\n"
 147              "  curvetun --server -4 -u -N --port 6666 --stun stunserver.org\n"
 148              "  curvetun --client=ethz\n\n"
 149              "Note:\n"
 150              "  There is no default port specified, so that you are forced\n"
 151              "  to select your own! For client/server status messages see syslog!\n"
 152              "  This software is an experimental prototype intended for researchers.\n\n"
 153              "Secret ingredient: 7647-14-5\n\n"
 154              "Please report bugs to <bugs@netsniff-ng.org>\n"
 155              "Copyright (C) 2011-2012 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n"
 156              "License: GNU GPL version 2.0\n"
 157              "This is free software: you are free to change and redistribute it.\n"
 158              "There is NO WARRANTY, to the extent permitted by law.\n");
 159         die();
 160 }
 161
 162 static void version(void)
 163 {
 164         printf("\ncurvetun %s, lightweight curve25519-based VPN/IP tunnel\n",
 165                VERSION_STRING);
 166         puts("http://www.netsniff-ng.org\n\n"
 167              "Please report bugs to <bugs@netsniff-ng.org>\n"
 168              "Copyright (C) 2011-2012 Daniel Borkmann <daniel@netsniff-ng.org>\n"
 169              "License: GNU GPL version 2.0\n"
 170              "This is free software: you are free to change and redistribute it.\n"
 171              "There is NO WARRANTY, to the extent permitted by law.\n");
 172         die();
 173 }
 174
 175 static void check_file_or_die(char *home, char *file, int maybeempty)
 176 {
 177         char path[PATH_MAX];
 178         struct stat st;
 179
 180         memset(path, 0, sizeof(path));
 181         slprintf(path, sizeof(path), "%s/%s", home, file);
 182
 183         if (stat(path, &st))
 184                 panic("No such file %s! Type --help for further information\n",
 185                       path);
 186
 187         if (!S_ISREG(st.st_mode))
 188                 panic("%s is not a regular file!\n", path);
 189
 190         if ((st.st_mode & ~S_IFREG) != (S_IRUSR | S_IWUSR))
 191                 panic("You have set too many permissions on %s (%o)!\n",
 192                       path, st.st_mode);
 193
 194         if (maybeempty == 0 && st.st_size == 0)
 195                 panic("%s is empty!\n", path);
 196 }
 197
 198 static void check_config_exists_or_die(char *home)
 199 {
 200         if (!home)
 201                 panic("No home dir specified!\n");
 202
 203         check_file_or_die(home, FILE_CLIENTS, 1);
 204         check_file_or_die(home, FILE_SERVERS, 1);
 205         check_file_or_die(home, FILE_PRIVKEY, 0);
 206         check_file_or_die(home, FILE_PUBKEY, 0);
 207         check_file_or_die(home, FILE_USERNAM, 0);
 208 }
 209
 210 static char *fetch_home_dir(void)
 211 {
 212         char *home = getenv("HOME");
 213         if (!home)
 214                 panic("No HOME defined!\n");
 215         return home;
 216 }
 217
 218 static void write_username(char *home)
 219 {
 220         int fd, ret;
 221         char path[PATH_MAX];
 222         char user[512];
 223
 224         memset(path, 0, sizeof(path));
 225         slprintf(path, sizeof(path), "%s/%s", home, FILE_USERNAM);
 226
 227         printf("Username: [%s] ", getenv("USER"));
 228         fflush(stdout);
 229
 230         memset(user, 0, sizeof(user));
 231         if (fgets(user, sizeof(user), stdin) == NULL)
 232                 panic("Could not read from stdin!\n");
 233         user[sizeof(user) - 1] = 0;
 234         user[strlen(user) - 1] = 0; /* omit last \n */
 235         if (strlen(user) == 0)
 236                 strlcpy(user, getenv("USER"), sizeof(user));
 237
 238         fd = open_or_die_m(path, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
 239
 240         ret = write(fd, user, strlen(user));
 241         if (ret != strlen(user))
 242                 panic("Could not write username!\n");
 243
 244         close(fd);
 245
 246         printf("Username written to %s!\n", path);
 247 }
 248
 249 static void create_curvedir(char *home)
 250 {
 251         int ret;
 252         char path[PATH_MAX];
 253
 254         memset(path, 0, sizeof(path));
 255         slprintf(path, sizeof(path), "%s/%s", home, ".curvetun/");
 256
 257         errno = 0;
 258
 259         ret = mkdir(path, S_IRWXU);
 260         if (ret < 0 && errno != EEXIST)
 261                 panic("Cannot create curvetun dir!\n");
 262
 263         printf("curvetun directory %s created!\n", path);
 264         /* We also create empty files for clients and servers! */
 265
 266         memset(path, 0, sizeof(path));
 267         slprintf(path, sizeof(path), "%s/%s", home, FILE_CLIENTS);
 268
 269         create_or_die(path, S_IRUSR | S_IWUSR);
 270
 271         printf("Empty client file written to %s!\n", path);
 272
 273         memset(path, 0, sizeof(path));
 274         slprintf(path, sizeof(path), "%s/%s", home, FILE_SERVERS);
 275
 276         create_or_die(path, S_IRUSR | S_IWUSR);
 277
 278         printf("Empty server file written to %s!\n", path);
 279 }
 280
 281 static void create_keypair(char *home)
 282 {
 283         int fd, err = 0;
 284         ssize_t ret;
 285         unsigned char publickey[crypto_box_curve25519xsalsa20poly1305_PUBLICKEYBYTES] = { 0 };
 286         unsigned char secretkey[crypto_box_curve25519xsalsa20poly1305_SECRETKEYBYTES] = { 0 };
 287         char path[PATH_MAX];
 288         const char * errstr = NULL;
 289
 290         printf("Reading from %s (this may take a while) ...\n", CURVETUN_ENTROPY_SOURCE);
 291
 292         fd = open_or_die(CURVETUN_ENTROPY_SOURCE, O_RDONLY);
 293
 294         ret = read_exact(fd, secretkey, sizeof(secretkey), 0);
 295         if (ret != sizeof(secretkey)) {
 296                 err = EIO;
 297                 errstr = "Cannot read from "CURVETUN_ENTROPY_SOURCE"!\n";
 298                 goto out;
 299         }
 300
 301         close(fd);
 302
 303         crypto_scalarmult_curve25519_base(publickey, secretkey);
 304
 305         memset(path, 0, sizeof(path));
 306         slprintf(path, sizeof(path), "%s/%s", home, FILE_PUBKEY);
 307
 308         fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
 309         if (fd < 0) {
 310                 err = EIO;
 311                 errstr = "Cannot open pubkey file!\n";
 312                 goto out;
 313         }
 314
 315         ret = write(fd, publickey, sizeof(publickey));
 316         if (ret != sizeof(publickey)) {
 317                 err = EIO;
 318                 errstr = "Cannot write public key!\n";
 319                 goto out;
 320         }
 321
 322         close(fd);
 323
 324         printf("Public key written to %s!\n", path);
 325
 326         memset(path, 0, sizeof(path));
 327         slprintf(path, sizeof(path), "%s/%s", home, FILE_PRIVKEY);
 328
 329         fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
 330         if (fd < 0) {
 331                 err = EIO;
 332                 errstr = "Cannot open privkey file!\n";
 333                 goto out;
 334         }
 335
 336         ret = write(fd, secretkey, sizeof(secretkey));
 337         if (ret != sizeof(secretkey)) {
 338                 err = EIO;
 339                 errstr = "Cannot write private key!\n";
 340                 goto out;
 341         }
 342 out:
 343         close(fd);
 344
 345         xmemset(publickey, 0, sizeof(publickey));
 346         xmemset(secretkey, 0, sizeof(secretkey));
 347
 348         if (err)
 349                 panic("%s: %s", errstr, strerror(errno));
 350         else
 351                 printf("Private key written to %s!\n", path);
 352 }
 353
 354 static void check_config_keypair_or_die(char *home)
 355 {
 356         int fd, err;
 357         ssize_t ret;
 358         const char * errstr = NULL;
 359         unsigned char publickey[crypto_box_curve25519xsalsa20poly1305_PUBLICKEYBYTES];
 360         unsigned char publicres[crypto_box_curve25519xsalsa20poly1305_PUBLICKEYBYTES];
 361         unsigned char secretkey[crypto_box_curve25519xsalsa20poly1305_SECRETKEYBYTES];
 362         char path[PATH_MAX];
 363
 364         memset(path, 0, sizeof(path));
 365         slprintf(path, sizeof(path), "%s/%s", home, FILE_PRIVKEY);
 366
 367         fd = open(path, O_RDONLY);
 368         if (fd < 0) {
 369                 err = EIO;
 370                 errstr = "Cannot open privkey file!\n";
 371                 goto out;
 372         }
 373
 374         ret = read(fd, secretkey, sizeof(secretkey));
 375         if (ret != sizeof(secretkey)) {
 376                 err = EIO;
 377                 errstr = "Cannot read private key!\n";
 378                 goto out;
 379         }
 380
 381         close(fd);
 382
 383         memset(path, 0, sizeof(path));
 384         slprintf(path, sizeof(path), "%s/%s", home, FILE_PUBKEY);
 385
 386         fd = open(path, O_RDONLY);
 387         if (fd < 0) {
 388                 err = EIO;
 389                 errstr = "Cannot open pubkey file!\n";
 390                 goto out;
 391         }
 392
 393         ret = read(fd, publickey, sizeof(publickey));
 394         if (ret != sizeof(publickey)) {
 395                 err = EIO;
 396                 errstr = "Cannot read public key!\n";
 397                 goto out;
 398         }
 399
 400         crypto_scalarmult_curve25519_base(publicres, secretkey);
 401
 402         err = crypto_verify_32(publicres, publickey);
 403         if (err) {
 404                 err = EINVAL;
 405                 errstr = "WARNING: your keypair is corrupted!!! You need to "
 406                          "generate new keys!!!\n";
 407                 goto out;
 408         }
 409 out:
 410         close(fd);
 411
 412         xmemset(publickey, 0, sizeof(publickey));
 413         xmemset(publicres, 0, sizeof(publicres));
 414         xmemset(secretkey, 0, sizeof(secretkey));
 415
 416         if (err)
 417                 panic("%s: %s\n", errstr, strerror(errno));
 418 }
 419
 420 static int main_keygen(char *home)
 421 {
 422         create_curvedir(home);
 423         write_username(home);
 424         create_keypair(home);
 425         check_config_keypair_or_die(home);
 426
 427         return 0;
 428 }
 429
 430 static int main_export(char *home)
 431 {
 432         int fd, i;
 433         ssize_t ret;
 434         char path[PATH_MAX], tmp[64];
 435
 436         check_config_exists_or_die(home);
 437         check_config_keypair_or_die(home);
 438
 439         printf("Your exported public information:\n\n");
 440
 441         memset(path, 0, sizeof(path));
 442         slprintf(path, sizeof(path), "%s/%s", home, FILE_USERNAM);
 443
 444         fd = open_or_die(path, O_RDONLY);
 445
 446         while ((ret = read(fd, tmp, sizeof(tmp))) > 0) {
 447                 ret = write(STDOUT_FILENO, tmp, ret);
 448         }
 449
 450         close(fd);
 451
 452         printf(";");
 453
 454         memset(path, 0, sizeof(path));
 455         slprintf(path, sizeof(path), "%s/%s", home, FILE_PUBKEY);
 456
 457         fd = open_or_die(path, O_RDONLY);
 458
 459         ret = read(fd, tmp, sizeof(tmp));
 460         if (ret != crypto_box_curve25519xsalsa20poly1305_PUBLICKEYBYTES)
 461                 panic("Cannot read public key!\n");
 462
 463         for (i = 0; i < ret; ++i)
 464                 if (i == ret - 1)
 465                         printf("%02x\n\n", (unsigned char) tmp[i]);
 466                 else
 467                         printf("%02x:", (unsigned char) tmp[i]);
 468
 469         close(fd);
 470         fflush(stdout);
 471
 472         return 0;
 473 }
 474
 475 static int main_dumpc(char *home)
 476 {
 477         check_config_exists_or_die(home);
 478         check_config_keypair_or_die(home);
 479
 480         printf("Your clients:\n\n");
 481
 482         parse_userfile_and_generate_user_store_or_die(home);
 483
 484         dump_user_store();
 485
 486         destroy_user_store();
 487
 488         printf("\n");
 489         die();
 490         return 0;
 491 }
 492
 493 static int main_dumps(char *home)
 494 {
 495         check_config_exists_or_die(home);
 496         check_config_keypair_or_die(home);
 497
 498         printf("Your servers:\n\n");
 499
 500         parse_userfile_and_generate_serv_store_or_die(home);
 501
 502         dump_serv_store();
 503
 504         destroy_serv_store();
 505
 506         printf("\n");
 507         die();
 508         return 0;
 509 }
 510
 511 static void daemonize(const char *lockfile)
 512 {
 513         char pidstr[8];
 514         mode_t lperm = S_IRWXU | S_IRGRP | S_IXGRP; /* 0750 */
 515         int lfp;
 516
 517         if (getppid() == 1)
 518                 return;
 519
 520         if (daemon(0, 0))
 521                 panic("Cannot daemonize: %s", strerror(errno));
 522
 523         umask(lperm);
 524         if (lockfile) {
 525                 lfp = open(lockfile, O_RDWR | O_CREAT | O_EXCL,
 526                            S_IRUSR | S_IWUSR | S_IRGRP);
 527                 if (lfp < 0)
 528                         syslog_panic("Cannot create lockfile at %s! "
 529                                      "curvetun server already running?\n",
 530                                      lockfile);
 531
 532                 slprintf(pidstr, sizeof(pidstr), "%u", getpid());
 533                 if (write(lfp, pidstr, strlen(pidstr)) <= 0)
 534                         syslog_panic("Could not write pid to pidfile %s",
 535                                      lockfile);
 536
 537                 close(lfp);
 538         }
 539 }
 540
 541 static int main_client(char *home, char *dev, char *alias, int daemon)
 542 {
 543         int ret, udp;
 544         char *host, *port;
 545
 546         check_config_exists_or_die(home);
 547         check_config_keypair_or_die(home);
 548
 549         parse_userfile_and_generate_serv_store_or_die(home);
 550
 551         get_serv_store_entry_by_alias(alias, alias ? strlen(alias) + 1 : 0,
 552                                       &host, &port, &udp);
 553         if (!host || !port || udp < 0)
 554                 panic("Did not find alias/entry in configuration!\n");
 555
 556         printf("Using [%s] -> %s:%s via %s as endpoint!\n",
 557                alias ? : "default", host, port, udp ? "udp" : "tcp");
 558         if (daemon)
 559                 daemonize(NULL);
 560
 561         ret = client_main(home, dev, host, port, udp);
 562
 563         destroy_serv_store();
 564
 565         return ret;
 566 }
 567
 568 static int main_server(char *home, char *dev, char *port, int udp,
 569                        int ipv4, int daemon, int log)
 570 {
 571         int ret;
 572
 573         check_config_exists_or_die(home);
 574         check_config_keypair_or_die(home);
 575
 576         if (daemon)
 577                 daemonize(LOCKFILE);
 578
 579         ret = server_main(home, dev, port, udp, ipv4, log);
 580
 581         unlink(LOCKFILE);
 582
 583         return ret;
 584 }
 585
 586 int main(int argc, char **argv)
 587 {
 588         int ret = 0, c, opt_index, udp = 0, ipv4 = -1, daemon = 1, log = 1;
 589         char *port = NULL, *stun = NULL, *dev = NULL, *home = NULL, *alias = NULL;
 590         enum working_mode wmode = MODE_UNKNOW;
 591
 592         if (getuid() != geteuid())
 593                 if (seteuid(getuid()));
 594
 595         home = fetch_home_dir();
 596
 597         while ((c = getopt_long(argc, argv, short_options, long_options,
 598                &opt_index)) != EOF) {
 599                 switch (c) {
 600                 case 'h':
 601                         help();
 602                         break;
 603                 case 'v':
 604                         version();
 605                         break;
 606                 case 'D':
 607                         daemon = 0;
 608                         break;
 609                 case 'N':
 610                         log = 0;
 611                         break;
 612                 case 'C':
 613                         wmode = MODE_DUMPC;
 614                         break;
 615                 case 'S':
 616                         wmode = MODE_DUMPS;
 617                         break;
 618                 case 'c':
 619                         wmode = MODE_CLIENT;
 620                         if (optarg) {
 621                                 if (*optarg == '=')
 622                                         optarg++;
 623                                 alias = xstrdup(optarg);
 624                         }
 625                         break;
 626                 case 'd':
 627                         dev = xstrdup(optarg);
 628                         break;
 629                 case 'k':
 630                         wmode = MODE_KEYGEN;
 631                         break;
 632                 case '4':
 633                         ipv4 = 1;
 634                         break;
 635                 case '6':
 636                         ipv4 = 0;
 637                         break;
 638                 case 'x':
 639                         wmode = MODE_EXPORT;
 640                         break;
 641                 case 's':
 642                         wmode = MODE_SERVER;
 643                         break;
 644                 case 'u':
 645                         udp = 1;
 646                         break;
 647                 case 't':
 648                         stun = xstrdup(optarg);
 649                         break;
 650                 case 'p':
 651                         port = xstrdup(optarg);
 652                         break;
 653                 case '?':
 654                         switch (optopt) {
 655                         case 't':
 656                         case 'd':
 657                         case 'u':
 658                         case 'p':
 659                                 panic("Option -%c requires an argument!\n",
 660                                       optopt);
 661                         default:
 662                                 if (isprint(optopt))
 663                                         whine("Unknown option character "
 664                                               "`0x%X\'!\n", optopt);
 665                                 die();
 666                         }
 667                 default:
 668                         break;
 669                 }
 670         }
 671
 672         if (argc < 2)
 673                 help();
 674
 675         register_signal(SIGINT, signal_handler);
 676         register_signal(SIGHUP, signal_handler);
 677         register_signal(SIGTERM, signal_handler);
 678         register_signal(SIGPIPE, signal_handler);
 679
 680         header();
 681
 682         curve25519_selftest();
 683
 684         switch (wmode) {
 685         case MODE_KEYGEN:
 686                 ret = main_keygen(home);
 687                 break;
 688         case MODE_EXPORT:
 689                 ret = main_export(home);
 690                 break;
 691         case MODE_DUMPC:
 692                 ret = main_dumpc(home);
 693                 break;
 694         case MODE_DUMPS:
 695                 ret = main_dumps(home);
 696                 break;
 697         case MODE_CLIENT:
 698                 ret = main_client(home, dev, alias, daemon);
 699                 break;
 700         case MODE_SERVER:
 701                 if (!port)
 702                         panic("No port specified!\n");
 703                 if (stun)
 704                         print_stun_probe(stun, 3478, strtoul(port, NULL, 10));
 705                 ret = main_server(home, dev, port, udp, ipv4, daemon, log);
 706                 break;
 707         default:
 708                 die();
 709         }
 710
 711         if (dev)
 712                 xfree(dev);
 713         if (stun)
 714                 xfree(stun);
 715         if (port)
 716                 xfree(port);
 717         if (alias)
 718                 xfree(alias);
 719
 720         return ret;
 721 }