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 <sys/fsuid.h>
  48 #include <netinet/in.h>
  49 #include <unistd.h>
  50 #include <signal.h>
  51
  52 #include "xutils.h"
  53 #include "die.h"
  54 #include "xmalloc.h"
  55 #include "curvetun.h"
  56 #include "curve.h"
  57 #include "ct_usermgmt.h"
  58 #include "ct_servmgmt.h"
  59 #include "xio.h"
  60 #include "tprintf.h"
  61 #include "crypto_verify_32.h"
  62 #include "crypto_box_curve25519xsalsa20poly1305.h"
  63 #include "crypto_scalarmult_curve25519.h"
  64 #include "crypto_auth_hmacsha512256.h"
  65
  66 #define CURVETUN_ENTROPY_SOURCE "/dev/random"
  67
  68 extern void print_stun_probe(char *server, uint16_t sport, uint16_t tunport);
  69
  70 enum working_mode {
  71         MODE_UNKNOW,
  72         MODE_KEYGEN,
  73         MODE_EXPORT,
  74         MODE_DUMPC,
  75         MODE_DUMPS,
  76         MODE_CLIENT,
  77         MODE_SERVER,
  78 };
  79
  80 volatile sig_atomic_t sigint = 0;
  81
  82 static const char *short_options = "kxc::svhp:t:d:uCS46DN";
  83 static const struct option long_options[] = {
  84         {"client",      optional_argument,      NULL, 'c'},
  85         {"dev",         required_argument,      NULL, 'd'},
  86         {"port",        required_argument,      NULL, 'p'},
  87         {"stun",        required_argument,      NULL, 't'},
  88         {"keygen",      no_argument,            NULL, 'k'},
  89         {"export",      no_argument,            NULL, 'x'},
  90         {"dumpc",       no_argument,            NULL, 'C'},
  91         {"dumps",       no_argument,            NULL, 'S'},
  92         {"no-logging",  no_argument,            NULL, 'N'},
  93         {"server",      no_argument,            NULL, 's'},
  94         {"udp",         no_argument,            NULL, 'u'},
  95         {"ipv4",        no_argument,            NULL, '4'},
  96         {"ipv6",        no_argument,            NULL, '6'},
  97         {"nofork",      no_argument,            NULL, 'D'},
  98         {"version",     no_argument,            NULL, 'v'},
  99         {"help",        no_argument,            NULL, 'h'},
 100         {NULL, 0, NULL, 0}
 101 };
 102
 103 static void signal_handler(int number)
 104 {
 105         switch (number) {
 106         case SIGINT:
 107                 sigint = 1;
 108                 break;
 109         default:
 110                 break;
 111         }
 112 }
 113
 114 static void header(void)
 115 {
 116         printf("%s%s%s\n", colorize_start(bold), "curvetun "
 117                VERSION_STRING, colorize_end());
 118 }
 119
 120 static void help(void)
 121 {
 122         printf("\ncurvetun %s, lightweight curve25519-based VPN/IP tunnel\n",
 123                VERSION_STRING);
 124         puts("http://www.netsniff-ng.org\n\n"
 125              "Usage: curvetun [options]\n"
 126              "Options, general:\n"
 127              "  -k|--keygen             Generate public/private keypair\n"
 128              "  -x|--export             Export your public data for remote servers\n"
 129              "  -C|--dumpc              Dump parsed clients\n"
 130              "  -S|--dumps              Dump parsed servers\n"
 131              "  -D|--nofork             Do not daemonize\n"
 132              "  -d|--dev <tun>          Networking tunnel device, e.g. tun0\n"
 133              "  -v|--version            Print version\n"
 134              "  -h|--help               Print this help\n"
 135              "  -c|--client[=alias]     Client mode, server alias optional\n"
 136              "  -s|--server             Server mode, options follow below\n"
 137              "  -N|--no-logging         Disable server logging (for better anonymity)\n"
 138              "  -p|--port <num>         Server port number (mandatory)\n"
 139              "  -t|--stun <server>      Show public IP/Port mapping via STUN\n"
 140              "  -u|--udp                Use UDP as carrier instead of TCP\n"
 141              "  -4|--ipv4               Tunnel devices are IPv4\n"
 142              "  -6|--ipv6               Tunnel devices are IPv6\n"
 143              "                          (default: same as carrier protocol)\n\n"
 144              "Example:\n"
 145              "  See Documentation/Curvetun for a configuration example.\n"
 146              "  curvetun --keygen\n"
 147              "  curvetun --export\n"
 148              "  curvetun --server -4 -u -N --port 6666 --stun stunserver.org\n"
 149              "  curvetun --client=ethz\n\n"
 150              "Note:\n"
 151              "  There is no default port specified, so that you are forced\n"
 152              "  to select your own! For client/server status messages see syslog!\n"
 153              "  This software is an experimental prototype intended for researchers.\n\n"
 154              "Secret ingredient: 7647-14-5\n\n"
 155              "Please report bugs to <bugs@netsniff-ng.org>\n"
 156              "Copyright (C) 2011-2012 Daniel Borkmann <dborkma@tik.ee.ethz.ch>,\n"
 157              "License: GNU GPL version 2.0\n"
 158              "This is free software: you are free to change and redistribute it.\n"
 159              "There is NO WARRANTY, to the extent permitted by law.\n");
 160         die();
 161 }
 162
 163 static void version(void)
 164 {
 165         printf("\ncurvetun %s, lightweight curve25519-based VPN/IP tunnel\n",
 166                VERSION_STRING);
 167         puts("http://www.netsniff-ng.org\n\n"
 168              "Please report bugs to <bugs@netsniff-ng.org>\n"
 169              "Copyright (C) 2011-2012 Daniel Borkmann <daniel@netsniff-ng.org>\n"
 170              "License: GNU GPL version 2.0\n"
 171              "This is free software: you are free to change and redistribute it.\n"
 172              "There is NO WARRANTY, to the extent permitted by law.\n");
 173         die();
 174 }
 175
 176 static void check_file_or_die(char *home, char *file, int maybeempty)
 177 {
 178         char path[PATH_MAX];
 179         struct stat st;
 180
 181         memset(path, 0, sizeof(path));
 182         slprintf(path, sizeof(path), "%s/%s", home, file);
 183
 184         if (stat(path, &st))
 185                 panic("No such file %s! Type --help for further information\n",
 186                       path);
 187
 188         if (!S_ISREG(st.st_mode))
 189                 panic("%s is not a regular file!\n", path);
 190
 191         if ((st.st_mode & ~S_IFREG) != (S_IRUSR | S_IWUSR))
 192                 panic("You have set too many permissions on %s (%o)!\n",
 193                       path, st.st_mode);
 194
 195         if (maybeempty == 0 && st.st_size == 0)
 196                 panic("%s is empty!\n", path);
 197 }
 198
 199 static void check_config_exists_or_die(char *home)
 200 {
 201         if (!home)
 202                 panic("No home dir specified!\n");
 203
 204         check_file_or_die(home, FILE_CLIENTS, 1);
 205         check_file_or_die(home, FILE_SERVERS, 1);
 206         check_file_or_die(home, FILE_PRIVKEY, 0);
 207         check_file_or_die(home, FILE_PUBKEY, 0);
 208         check_file_or_die(home, FILE_USERNAM, 0);
 209 }
 210
 211 static char *fetch_home_dir(void)
 212 {
 213         char *home = getenv("HOME");
 214         if (!home)
 215                 panic("No HOME defined!\n");
 216         return home;
 217 }
 218
 219 static void write_username(char *home)
 220 {
 221         int fd, ret;
 222         char path[PATH_MAX];
 223         char user[512];
 224
 225         memset(path, 0, sizeof(path));
 226         slprintf(path, sizeof(path), "%s/%s", home, FILE_USERNAM);
 227
 228         printf("Username: [%s] ", getenv("USER"));
 229         fflush(stdout);
 230
 231         memset(user, 0, sizeof(user));
 232         if (fgets(user, sizeof(user), stdin) == NULL)
 233                 panic("Could not read from stdin!\n");
 234         user[sizeof(user) - 1] = 0;
 235         user[strlen(user) - 1] = 0; /* omit last \n */
 236         if (strlen(user) == 0)
 237                 strlcpy(user, getenv("USER"), sizeof(user));
 238
 239         fd = open_or_die_m(path, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
 240
 241         ret = write(fd, user, strlen(user));
 242         if (ret != strlen(user))
 243                 panic("Could not write username!\n");
 244
 245         close(fd);
 246
 247         printf("Username written to %s!\n", path);
 248 }
 249
 250 static void create_curvedir(char *home)
 251 {
 252         int ret;
 253         char path[PATH_MAX];
 254
 255         memset(path, 0, sizeof(path));
 256         slprintf(path, sizeof(path), "%s/%s", home, ".curvetun/");
 257
 258         errno = 0;
 259
 260         ret = mkdir(path, S_IRWXU);
 261         if (ret < 0 && errno != EEXIST)
 262                 panic("Cannot create curvetun dir!\n");
 263
 264         printf("curvetun directory %s created!\n", path);
 265         /* We also create empty files for clients and servers! */
 266
 267         memset(path, 0, sizeof(path));
 268         slprintf(path, sizeof(path), "%s/%s", home, FILE_CLIENTS);
 269
 270         create_or_die(path, S_IRUSR | S_IWUSR);
 271
 272         printf("Empty client file written to %s!\n", path);
 273
 274         memset(path, 0, sizeof(path));
 275         slprintf(path, sizeof(path), "%s/%s", home, FILE_SERVERS);
 276
 277         create_or_die(path, S_IRUSR | S_IWUSR);
 278
 279         printf("Empty server file written to %s!\n", path);
 280 }
 281
 282 static void create_keypair(char *home)
 283 {
 284         int fd, err = 0;
 285         ssize_t ret;
 286         unsigned char publickey[crypto_box_curve25519xsalsa20poly1305_PUBLICKEYBYTES] = { 0 };
 287         unsigned char secretkey[crypto_box_curve25519xsalsa20poly1305_SECRETKEYBYTES] = { 0 };
 288         char path[PATH_MAX];
 289         const char * errstr = NULL;
 290
 291         printf("Reading from %s (this may take a while) ...\n", CURVETUN_ENTROPY_SOURCE);
 292
 293         fd = open_or_die(CURVETUN_ENTROPY_SOURCE, O_RDONLY);
 294
 295         ret = read_exact(fd, secretkey, sizeof(secretkey), 0);
 296         if (ret != sizeof(secretkey)) {
 297                 err = EIO;
 298                 errstr = "Cannot read from "CURVETUN_ENTROPY_SOURCE"!\n";
 299                 goto out;
 300         }
 301
 302         close(fd);
 303
 304         crypto_scalarmult_curve25519_base(publickey, secretkey);
 305
 306         memset(path, 0, sizeof(path));
 307         slprintf(path, sizeof(path), "%s/%s", home, FILE_PUBKEY);
 308
 309         fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
 310         if (fd < 0) {
 311                 err = EIO;
 312                 errstr = "Cannot open pubkey file!\n";
 313                 goto out;
 314         }
 315
 316         ret = write(fd, publickey, sizeof(publickey));
 317         if (ret != sizeof(publickey)) {
 318                 err = EIO;
 319                 errstr = "Cannot write public key!\n";
 320                 goto out;
 321         }
 322
 323         close(fd);
 324
 325         printf("Public key written to %s!\n", path);
 326
 327         memset(path, 0, sizeof(path));
 328         slprintf(path, sizeof(path), "%s/%s", home, FILE_PRIVKEY);
 329
 330         fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
 331         if (fd < 0) {
 332                 err = EIO;
 333                 errstr = "Cannot open privkey file!\n";
 334                 goto out;
 335         }
 336
 337         ret = write(fd, secretkey, sizeof(secretkey));
 338         if (ret != sizeof(secretkey)) {
 339                 err = EIO;
 340                 errstr = "Cannot write private key!\n";
 341                 goto out;
 342         }
 343 out:
 344         close(fd);
 345
 346         xmemset(publickey, 0, sizeof(publickey));
 347         xmemset(secretkey, 0, sizeof(secretkey));
 348
 349         if (err)
 350                 panic("%s: %s", errstr, strerror(errno));
 351         else
 352                 printf("Private key written to %s!\n", path);
 353 }
 354
 355 static void check_config_keypair_or_die(char *home)
 356 {
 357         int fd, err;
 358         ssize_t ret;
 359         const char * errstr = NULL;
 360         unsigned char publickey[crypto_box_curve25519xsalsa20poly1305_PUBLICKEYBYTES];
 361         unsigned char publicres[crypto_box_curve25519xsalsa20poly1305_PUBLICKEYBYTES];
 362         unsigned char secretkey[crypto_box_curve25519xsalsa20poly1305_SECRETKEYBYTES];
 363         char path[PATH_MAX];
 364
 365         memset(path, 0, sizeof(path));
 366         slprintf(path, sizeof(path), "%s/%s", home, FILE_PRIVKEY);
 367
 368         fd = open(path, O_RDONLY);
 369         if (fd < 0) {
 370                 err = EIO;
 371                 errstr = "Cannot open privkey file!\n";
 372                 goto out;
 373         }
 374
 375         ret = read(fd, secretkey, sizeof(secretkey));
 376         if (ret != sizeof(secretkey)) {
 377                 err = EIO;
 378                 errstr = "Cannot read private key!\n";
 379                 goto out;
 380         }
 381
 382         close(fd);
 383
 384         memset(path, 0, sizeof(path));
 385         slprintf(path, sizeof(path), "%s/%s", home, FILE_PUBKEY);
 386
 387         fd = open(path, O_RDONLY);
 388         if (fd < 0) {
 389                 err = EIO;
 390                 errstr = "Cannot open pubkey file!\n";
 391                 goto out;
 392         }
 393
 394         ret = read(fd, publickey, sizeof(publickey));
 395         if (ret != sizeof(publickey)) {
 396                 err = EIO;
 397                 errstr = "Cannot read public key!\n";
 398                 goto out;
 399         }
 400
 401         crypto_scalarmult_curve25519_base(publicres, secretkey);
 402
 403         err = crypto_verify_32(publicres, publickey);
 404         if (err) {
 405                 err = EINVAL;
 406                 errstr = "WARNING: your keypair is corrupted!!! You need to "
 407                          "generate new keys!!!\n";
 408                 goto out;
 409         }
 410 out:
 411         close(fd);
 412
 413         xmemset(publickey, 0, sizeof(publickey));
 414         xmemset(publicres, 0, sizeof(publicres));
 415         xmemset(secretkey, 0, sizeof(secretkey));
 416
 417         if (err)
 418                 panic("%s: %s\n", errstr, strerror(errno));
 419 }
 420
 421 static int main_keygen(char *home)
 422 {
 423         create_curvedir(home);
 424         write_username(home);
 425         create_keypair(home);
 426         check_config_keypair_or_die(home);
 427
 428         return 0;
 429 }
 430
 431 static int main_export(char *home)
 432 {
 433         int fd, i;
 434         ssize_t ret;
 435         char path[PATH_MAX], tmp[64];
 436
 437         check_config_exists_or_die(home);
 438         check_config_keypair_or_die(home);
 439
 440         printf("Your exported public information:\n\n");
 441
 442         memset(path, 0, sizeof(path));
 443         slprintf(path, sizeof(path), "%s/%s", home, FILE_USERNAM);
 444
 445         fd = open_or_die(path, O_RDONLY);
 446
 447         while ((ret = read(fd, tmp, sizeof(tmp))) > 0) {
 448                 ret = write(STDOUT_FILENO, tmp, ret);
 449         }
 450
 451         close(fd);
 452
 453         printf(";");
 454
 455         memset(path, 0, sizeof(path));
 456         slprintf(path, sizeof(path), "%s/%s", home, FILE_PUBKEY);
 457
 458         fd = open_or_die(path, O_RDONLY);
 459
 460         ret = read(fd, tmp, sizeof(tmp));
 461         if (ret != crypto_box_curve25519xsalsa20poly1305_PUBLICKEYBYTES)
 462                 panic("Cannot read public key!\n");
 463
 464         for (i = 0; i < ret; ++i)
 465                 if (i == ret - 1)
 466                         printf("%02x\n\n", (unsigned char) tmp[i]);
 467                 else
 468                         printf("%02x:", (unsigned char) tmp[i]);
 469
 470         close(fd);
 471         fflush(stdout);
 472
 473         return 0;
 474 }
 475
 476 static int main_dumpc(char *home)
 477 {
 478         check_config_exists_or_die(home);
 479         check_config_keypair_or_die(home);
 480
 481         printf("Your clients:\n\n");
 482
 483         parse_userfile_and_generate_user_store_or_die(home);
 484
 485         dump_user_store();
 486
 487         destroy_user_store();
 488
 489         printf("\n");
 490         die();
 491         return 0;
 492 }
 493
 494 static int main_dumps(char *home)
 495 {
 496         check_config_exists_or_die(home);
 497         check_config_keypair_or_die(home);
 498
 499         printf("Your servers:\n\n");
 500
 501         parse_userfile_and_generate_serv_store_or_die(home);
 502
 503         dump_serv_store();
 504
 505         destroy_serv_store();
 506
 507         printf("\n");
 508         die();
 509         return 0;
 510 }
 511
 512 static void daemonize(const char *lockfile)
 513 {
 514         char pidstr[8];
 515         mode_t lperm = S_IRWXU | S_IRGRP | S_IXGRP; /* 0750 */
 516         int lfp;
 517
 518         if (getppid() == 1)
 519                 return;
 520
 521         if (daemon(0, 0))
 522                 panic("Cannot daemonize: %s", strerror(errno));
 523
 524         umask(lperm);
 525         if (lockfile) {
 526                 lfp = open(lockfile, O_RDWR | O_CREAT | O_EXCL,
 527                            S_IRUSR | S_IWUSR | S_IRGRP);
 528                 if (lfp < 0)
 529                         syslog_panic("Cannot create lockfile at %s! "
 530                                      "curvetun server already running?\n",
 531                                      lockfile);
 532
 533                 slprintf(pidstr, sizeof(pidstr), "%u", getpid());
 534                 if (write(lfp, pidstr, strlen(pidstr)) <= 0)
 535                         syslog_panic("Could not write pid to pidfile %s",
 536                                      lockfile);
 537
 538                 close(lfp);
 539         }
 540 }
 541
 542 static int main_client(char *home, char *dev, char *alias, int daemon)
 543 {
 544         int ret, udp;
 545         char *host, *port;
 546
 547         check_config_exists_or_die(home);
 548         check_config_keypair_or_die(home);
 549
 550         parse_userfile_and_generate_serv_store_or_die(home);
 551
 552         get_serv_store_entry_by_alias(alias, alias ? strlen(alias) + 1 : 0,
 553                                       &host, &port, &udp);
 554         if (!host || !port || udp < 0)
 555                 panic("Did not find alias/entry in configuration!\n");
 556
 557         printf("Using [%s] -> %s:%s via %s as endpoint!\n",
 558                alias ? : "default", host, port, udp ? "udp" : "tcp");
 559         if (daemon)
 560                 daemonize(NULL);
 561
 562         ret = client_main(home, dev, host, port, udp);
 563
 564         destroy_serv_store();
 565
 566         return ret;
 567 }
 568
 569 static int main_server(char *home, char *dev, char *port, int udp,
 570                        int ipv4, int daemon, int log)
 571 {
 572         int ret;
 573
 574         check_config_exists_or_die(home);
 575         check_config_keypair_or_die(home);
 576
 577         if (daemon)
 578                 daemonize(LOCKFILE);
 579
 580         ret = server_main(home, dev, port, udp, ipv4, log);
 581
 582         unlink(LOCKFILE);
 583
 584         return ret;
 585 }
 586
 587 int main(int argc, char **argv)
 588 {
 589         int ret = 0, c, opt_index, udp = 0, ipv4 = -1, daemon = 1, log = 1;
 590         char *port = NULL, *stun = NULL, *dev = NULL, *home = NULL, *alias = NULL;
 591         enum working_mode wmode = MODE_UNKNOW;
 592
 593         setfsuid(getuid());
 594         setfsgid(getgid());
 595
 596         home = fetch_home_dir();
 597
 598         while ((c = getopt_long(argc, argv, short_options, long_options,
 599                &opt_index)) != EOF) {
 600                 switch (c) {
 601                 case 'h':
 602                         help();
 603                         break;
 604                 case 'v':
 605                         version();
 606                         break;
 607                 case 'D':
 608                         daemon = 0;
 609                         break;
 610                 case 'N':
 611                         log = 0;
 612                         break;
 613                 case 'C':
 614                         wmode = MODE_DUMPC;
 615                         break;
 616                 case 'S':
 617                         wmode = MODE_DUMPS;
 618                         break;
 619                 case 'c':
 620                         wmode = MODE_CLIENT;
 621                         if (optarg) {
 622                                 if (*optarg == '=')
 623                                         optarg++;
 624                                 alias = xstrdup(optarg);
 625                         }
 626                         break;
 627                 case 'd':
 628                         dev = xstrdup(optarg);
 629                         break;
 630                 case 'k':
 631                         wmode = MODE_KEYGEN;
 632                         break;
 633                 case '4':
 634                         ipv4 = 1;
 635                         break;
 636                 case '6':
 637                         ipv4 = 0;
 638                         break;
 639                 case 'x':
 640                         wmode = MODE_EXPORT;
 641                         break;
 642                 case 's':
 643                         wmode = MODE_SERVER;
 644                         break;
 645                 case 'u':
 646                         udp = 1;
 647                         break;
 648                 case 't':
 649                         stun = xstrdup(optarg);
 650                         break;
 651                 case 'p':
 652                         port = xstrdup(optarg);
 653                         break;
 654                 case '?':
 655                         switch (optopt) {
 656                         case 't':
 657                         case 'd':
 658                         case 'u':
 659                         case 'p':
 660                                 panic("Option -%c requires an argument!\n",
 661                                       optopt);
 662                         default:
 663                                 if (isprint(optopt))
 664                                         whine("Unknown option character "
 665                                               "`0x%X\'!\n", optopt);
 666                                 die();
 667                         }
 668                 default:
 669                         break;
 670                 }
 671         }
 672
 673         if (argc < 2)
 674                 help();
 675
 676         register_signal(SIGINT, signal_handler);
 677         register_signal(SIGHUP, signal_handler);
 678         register_signal(SIGTERM, signal_handler);
 679         register_signal(SIGPIPE, signal_handler);
 680
 681         header();
 682
 683         curve25519_selftest();
 684
 685         switch (wmode) {
 686         case MODE_KEYGEN:
 687                 ret = main_keygen(home);
 688                 break;
 689         case MODE_EXPORT:
 690                 ret = main_export(home);
 691                 break;
 692         case MODE_DUMPC:
 693                 ret = main_dumpc(home);
 694                 break;
 695         case MODE_DUMPS:
 696                 ret = main_dumps(home);
 697                 break;
 698         case MODE_CLIENT:
 699                 ret = main_client(home, dev, alias, daemon);
 700                 break;
 701         case MODE_SERVER:
 702                 if (!port)
 703                         panic("No port specified!\n");
 704                 if (stun)
 705                         print_stun_probe(stun, 3478, strtoul(port, NULL, 10));
 706                 ret = main_server(home, dev, port, udp, ipv4, daemon, log);
 707                 break;
 708         default:
 709                 die();
 710         }
 711
 712         if (dev)
 713                 xfree(dev);
 714         if (stun)
 715                 xfree(stun);
 716         if (port)
 717                 xfree(port);
 718         if (alias)
 719                 xfree(alias);
 720
 721         return ret;
 722 }