1 /* $OpenBSD: netcat.c,v 1.109 2012/07/07 15:33:02 haesbaert Exp $ */ 2 /* 3 * Copyright (c) 2001 Eric Jackson <ericj@monkey.org> 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * $FreeBSD$ 29 */ 30 31 /* 32 * Re-written nc(1) for OpenBSD. Original implementation by 33 * *Hobbit* <hobbit@avian.org>. 34 */ 35 36 #include <sys/limits.h> 37 #include <sys/types.h> 38 #include <sys/socket.h> 39 #include <sys/sysctl.h> 40 #include <sys/time.h> 41 #include <sys/un.h> 42 43 #include <netinet/in.h> 44 #include <netinet/in_systm.h> 45 #ifdef IPSEC 46 #include <netipsec/ipsec.h> 47 #endif 48 #include <netinet/tcp.h> 49 #include <netinet/ip.h> 50 #include <arpa/telnet.h> 51 52 #include <err.h> 53 #include <errno.h> 54 #include <getopt.h> 55 #include <netdb.h> 56 #include <poll.h> 57 #include <stdarg.h> 58 #include <stdio.h> 59 #include <stdlib.h> 60 #include <string.h> 61 #include <unistd.h> 62 #include <fcntl.h> 63 #include <limits.h> 64 #include "atomicio.h" 65 66 #ifndef SUN_LEN 67 #define SUN_LEN(su) \ 68 (sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path)) 69 #endif 70 71 #define PORT_MAX 65535 72 #define PORT_MAX_LEN 6 73 #define UNIX_DG_TMP_SOCKET_SIZE 19 74 75 /* Command Line Options */ 76 int dflag; /* detached, no stdin */ 77 unsigned int iflag; /* Interval Flag */ 78 int kflag; /* More than one connect */ 79 int lflag; /* Bind to local port */ 80 int nflag; /* Don't do name look up */ 81 int FreeBSD_Oflag; /* Do not use TCP options */ 82 char *Pflag; /* Proxy username */ 83 char *pflag; /* Localport flag */ 84 int rflag; /* Random ports flag */ 85 char *sflag; /* Source Address */ 86 int tflag; /* Telnet Emulation */ 87 int uflag; /* UDP - Default to TCP */ 88 int vflag; /* Verbosity */ 89 int xflag; /* Socks proxy */ 90 int zflag; /* Port Scan Flag */ 91 int Dflag; /* sodebug */ 92 int Iflag; /* TCP receive buffer size */ 93 int Oflag; /* TCP send buffer size */ 94 int Sflag; /* TCP MD5 signature option */ 95 int Tflag = -1; /* IP Type of Service */ 96 u_int rtableid; 97 98 int timeout = -1; 99 int family = AF_UNSPEC; 100 char *portlist[PORT_MAX+1]; 101 char *unix_dg_tmp_socket; 102 103 void atelnet(int, unsigned char *, unsigned int); 104 void build_ports(char *); 105 void help(void); 106 int local_listen(char *, char *, struct addrinfo); 107 void readwrite(int); 108 int remote_connect(const char *, const char *, struct addrinfo); 109 int timeout_connect(int, const struct sockaddr *, socklen_t); 110 int socks_connect(const char *, const char *, struct addrinfo, 111 const char *, const char *, struct addrinfo, int, const char *); 112 int udptest(int); 113 int unix_bind(char *); 114 int unix_connect(char *); 115 int unix_listen(char *); 116 void set_common_sockopts(int); 117 int map_tos(char *, int *); 118 void report_connect(const struct sockaddr *, socklen_t); 119 void usage(int); 120 121 #ifdef IPSEC 122 void add_ipsec_policy(int, char *); 123 124 char *ipsec_policy[2]; 125 #endif 126 127 int 128 main(int argc, char *argv[]) 129 { 130 int ch, s, ret, socksv, ipsec_count; 131 int numfibs; 132 size_t intsize = sizeof(int); 133 char *host, *uport; 134 struct addrinfo hints; 135 struct servent *sv; 136 socklen_t len; 137 struct sockaddr_storage cliaddr; 138 char *proxy; 139 const char *errstr, *proxyhost = "", *proxyport = NULL; 140 struct addrinfo proxyhints; 141 char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE]; 142 struct option longopts[] = { 143 { "no-tcpopt", no_argument, &FreeBSD_Oflag, 1 }, 144 { NULL, 0, NULL, 0 } 145 }; 146 147 ret = 1; 148 ipsec_count = 0; 149 s = 0; 150 socksv = 5; 151 host = NULL; 152 uport = NULL; 153 sv = NULL; 154 155 while ((ch = getopt_long(argc, argv, 156 "46DdEe:hI:i:klnoO:P:p:rSs:tT:UuV:vw:X:x:z", 157 longopts, NULL)) != -1) { 158 switch (ch) { 159 case '4': 160 family = AF_INET; 161 break; 162 case '6': 163 family = AF_INET6; 164 break; 165 case 'U': 166 family = AF_UNIX; 167 break; 168 case 'X': 169 if (strcasecmp(optarg, "connect") == 0) 170 socksv = -1; /* HTTP proxy CONNECT */ 171 else if (strcmp(optarg, "4") == 0) 172 socksv = 4; /* SOCKS v.4 */ 173 else if (strcmp(optarg, "5") == 0) 174 socksv = 5; /* SOCKS v.5 */ 175 else 176 errx(1, "unsupported proxy protocol"); 177 break; 178 case 'd': 179 dflag = 1; 180 break; 181 case 'e': 182 #ifdef IPSEC 183 ipsec_policy[ipsec_count++ % 2] = optarg; 184 #else 185 errx(1, "IPsec support unavailable."); 186 #endif 187 break; 188 case 'E': 189 #ifdef IPSEC 190 ipsec_policy[0] = "in ipsec esp/transport//require"; 191 ipsec_policy[1] = "out ipsec esp/transport//require"; 192 #else 193 errx(1, "IPsec support unavailable."); 194 #endif 195 break; 196 case 'h': 197 help(); 198 break; 199 case 'i': 200 iflag = strtonum(optarg, 0, UINT_MAX, &errstr); 201 if (errstr) 202 errx(1, "interval %s: %s", errstr, optarg); 203 break; 204 case 'k': 205 kflag = 1; 206 break; 207 case 'l': 208 lflag = 1; 209 break; 210 case 'n': 211 nflag = 1; 212 break; 213 case 'o': 214 fprintf(stderr, "option -o is deprecated.\n"); 215 break; 216 case 'P': 217 Pflag = optarg; 218 break; 219 case 'p': 220 pflag = optarg; 221 break; 222 case 'r': 223 rflag = 1; 224 break; 225 case 's': 226 sflag = optarg; 227 break; 228 case 't': 229 tflag = 1; 230 break; 231 case 'u': 232 uflag = 1; 233 break; 234 case 'V': 235 if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1) 236 errx(1, "Multiple FIBS not supported"); 237 rtableid = (unsigned int)strtonum(optarg, 0, 238 numfibs - 1, &errstr); 239 if (errstr) 240 errx(1, "rtable %s: %s", errstr, optarg); 241 break; 242 case 'v': 243 vflag = 1; 244 break; 245 case 'w': 246 timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr); 247 if (errstr) 248 errx(1, "timeout %s: %s", errstr, optarg); 249 timeout *= 1000; 250 break; 251 case 'x': 252 xflag = 1; 253 if ((proxy = strdup(optarg)) == NULL) 254 err(1, NULL); 255 break; 256 case 'z': 257 zflag = 1; 258 break; 259 case 'D': 260 Dflag = 1; 261 break; 262 case 'I': 263 Iflag = strtonum(optarg, 1, 65536 << 14, &errstr); 264 if (errstr != NULL) 265 errx(1, "TCP receive window %s: %s", 266 errstr, optarg); 267 break; 268 case 'O': 269 Oflag = strtonum(optarg, 1, 65536 << 14, &errstr); 270 if (errstr != NULL) { 271 if (strcmp(errstr, "invalid") != 0) 272 errx(1, "TCP send window %s: %s", 273 errstr, optarg); 274 } 275 break; 276 case 'S': 277 Sflag = 1; 278 break; 279 case 'T': 280 errstr = NULL; 281 errno = 0; 282 if (map_tos(optarg, &Tflag)) 283 break; 284 if (strlen(optarg) > 1 && optarg[0] == '0' && 285 optarg[1] == 'x') 286 Tflag = (int)strtol(optarg, NULL, 16); 287 else 288 Tflag = (int)strtonum(optarg, 0, 255, 289 &errstr); 290 if (Tflag < 0 || Tflag > 255 || errstr || errno) 291 errx(1, "illegal tos value %s", optarg); 292 break; 293 default: 294 usage(1); 295 } 296 } 297 argc -= optind; 298 argv += optind; 299 300 /* Cruft to make sure options are clean, and used properly. */ 301 if (argv[0] && !argv[1] && family == AF_UNIX) { 302 host = argv[0]; 303 uport = NULL; 304 } else if (argv[0] && !argv[1]) { 305 if (!lflag) 306 usage(1); 307 uport = argv[0]; 308 host = NULL; 309 } else if (argv[0] && argv[1]) { 310 host = argv[0]; 311 uport = argv[1]; 312 } else 313 usage(1); 314 315 if (lflag && sflag) 316 errx(1, "cannot use -s and -l"); 317 if (lflag && pflag) 318 errx(1, "cannot use -p and -l"); 319 if (lflag && zflag) 320 errx(1, "cannot use -z and -l"); 321 if (!lflag && kflag) 322 errx(1, "must use -l with -k"); 323 324 /* Get name of temporary socket for unix datagram client */ 325 if ((family == AF_UNIX) && uflag && !lflag) { 326 if (sflag) { 327 unix_dg_tmp_socket = sflag; 328 } else { 329 strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX", 330 UNIX_DG_TMP_SOCKET_SIZE); 331 if (mktemp(unix_dg_tmp_socket_buf) == NULL) 332 err(1, "mktemp"); 333 unix_dg_tmp_socket = unix_dg_tmp_socket_buf; 334 } 335 } 336 337 /* Initialize addrinfo structure. */ 338 if (family != AF_UNIX) { 339 memset(&hints, 0, sizeof(struct addrinfo)); 340 hints.ai_family = family; 341 hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 342 hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 343 if (nflag) 344 hints.ai_flags |= AI_NUMERICHOST; 345 } 346 347 if (xflag) { 348 if (uflag) 349 errx(1, "no proxy support for UDP mode"); 350 351 if (lflag) 352 errx(1, "no proxy support for listen"); 353 354 if (family == AF_UNIX) 355 errx(1, "no proxy support for unix sockets"); 356 357 /* XXX IPv6 transport to proxy would probably work */ 358 if (family == AF_INET6) 359 errx(1, "no proxy support for IPv6"); 360 361 if (sflag) 362 errx(1, "no proxy support for local source address"); 363 364 proxyhost = strsep(&proxy, ":"); 365 proxyport = proxy; 366 367 memset(&proxyhints, 0, sizeof(struct addrinfo)); 368 proxyhints.ai_family = family; 369 proxyhints.ai_socktype = SOCK_STREAM; 370 proxyhints.ai_protocol = IPPROTO_TCP; 371 if (nflag) 372 proxyhints.ai_flags |= AI_NUMERICHOST; 373 } 374 375 if (lflag) { 376 int connfd; 377 ret = 0; 378 379 if (family == AF_UNIX) { 380 if (uflag) 381 s = unix_bind(host); 382 else 383 s = unix_listen(host); 384 } 385 386 /* Allow only one connection at a time, but stay alive. */ 387 for (;;) { 388 if (family != AF_UNIX) 389 s = local_listen(host, uport, hints); 390 if (s < 0) 391 err(1, NULL); 392 /* 393 * For UDP and -k, don't connect the socket, let it 394 * receive datagrams from multiple socket pairs. 395 */ 396 if (uflag && kflag) 397 readwrite(s); 398 /* 399 * For UDP and not -k, we will use recvfrom() initially 400 * to wait for a caller, then use the regular functions 401 * to talk to the caller. 402 */ 403 else if (uflag && !kflag) { 404 int rv, plen; 405 char buf[16384]; 406 struct sockaddr_storage z; 407 408 len = sizeof(z); 409 plen = 2048; 410 rv = recvfrom(s, buf, plen, MSG_PEEK, 411 (struct sockaddr *)&z, &len); 412 if (rv < 0) 413 err(1, "recvfrom"); 414 415 rv = connect(s, (struct sockaddr *)&z, len); 416 if (rv < 0) 417 err(1, "connect"); 418 419 if (vflag) 420 report_connect((struct sockaddr *)&z, len); 421 422 readwrite(s); 423 } else { 424 len = sizeof(cliaddr); 425 connfd = accept(s, (struct sockaddr *)&cliaddr, 426 &len); 427 if (connfd == -1) 428 err(1, "accept"); 429 430 if (vflag) 431 report_connect((struct sockaddr *)&cliaddr, len); 432 433 readwrite(connfd); 434 close(connfd); 435 } 436 437 if (family != AF_UNIX) 438 close(s); 439 else if (uflag) { 440 if (connect(s, NULL, 0) < 0) 441 err(1, "connect"); 442 } 443 444 if (!kflag) 445 break; 446 } 447 } else if (family == AF_UNIX) { 448 ret = 0; 449 450 if ((s = unix_connect(host)) > 0 && !zflag) { 451 readwrite(s); 452 close(s); 453 } else 454 ret = 1; 455 456 if (uflag) 457 unlink(unix_dg_tmp_socket); 458 exit(ret); 459 460 } else { 461 int i = 0; 462 463 /* Construct the portlist[] array. */ 464 build_ports(uport); 465 466 /* Cycle through portlist, connecting to each port. */ 467 for (i = 0; portlist[i] != NULL; i++) { 468 if (s) 469 close(s); 470 471 if (xflag) 472 s = socks_connect(host, portlist[i], hints, 473 proxyhost, proxyport, proxyhints, socksv, 474 Pflag); 475 else 476 s = remote_connect(host, portlist[i], hints); 477 478 if (s < 0) 479 continue; 480 481 ret = 0; 482 if (vflag || zflag) { 483 /* For UDP, make sure we are connected. */ 484 if (uflag) { 485 if (udptest(s) == -1) { 486 ret = 1; 487 continue; 488 } 489 } 490 491 /* Don't look up port if -n. */ 492 if (nflag) 493 sv = NULL; 494 else { 495 sv = getservbyport( 496 ntohs(atoi(portlist[i])), 497 uflag ? "udp" : "tcp"); 498 } 499 500 fprintf(stderr, 501 "Connection to %s %s port [%s/%s] " 502 "succeeded!\n", host, portlist[i], 503 uflag ? "udp" : "tcp", 504 sv ? sv->s_name : "*"); 505 } 506 if (!zflag) 507 readwrite(s); 508 } 509 } 510 511 if (s) 512 close(s); 513 514 exit(ret); 515 } 516 517 /* 518 * unix_bind() 519 * Returns a unix socket bound to the given path 520 */ 521 int 522 unix_bind(char *path) 523 { 524 struct sockaddr_un sun; 525 int s; 526 527 /* Create unix domain socket. */ 528 if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM, 529 0)) < 0) 530 return (-1); 531 532 memset(&sun, 0, sizeof(struct sockaddr_un)); 533 sun.sun_family = AF_UNIX; 534 535 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 536 sizeof(sun.sun_path)) { 537 close(s); 538 errno = ENAMETOOLONG; 539 return (-1); 540 } 541 542 if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 543 close(s); 544 return (-1); 545 } 546 return (s); 547 } 548 549 /* 550 * unix_connect() 551 * Returns a socket connected to a local unix socket. Returns -1 on failure. 552 */ 553 int 554 unix_connect(char *path) 555 { 556 struct sockaddr_un sun; 557 int s; 558 559 if (uflag) { 560 if ((s = unix_bind(unix_dg_tmp_socket)) < 0) 561 return (-1); 562 } else { 563 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 564 return (-1); 565 } 566 (void)fcntl(s, F_SETFD, 1); 567 568 memset(&sun, 0, sizeof(struct sockaddr_un)); 569 sun.sun_family = AF_UNIX; 570 571 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 572 sizeof(sun.sun_path)) { 573 close(s); 574 errno = ENAMETOOLONG; 575 return (-1); 576 } 577 if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 578 close(s); 579 return (-1); 580 } 581 return (s); 582 583 } 584 585 /* 586 * unix_listen() 587 * Create a unix domain socket, and listen on it. 588 */ 589 int 590 unix_listen(char *path) 591 { 592 int s; 593 if ((s = unix_bind(path)) < 0) 594 return (-1); 595 596 if (listen(s, 5) < 0) { 597 close(s); 598 return (-1); 599 } 600 return (s); 601 } 602 603 /* 604 * remote_connect() 605 * Returns a socket connected to a remote host. Properly binds to a local 606 * port or source address if needed. Returns -1 on failure. 607 */ 608 int 609 remote_connect(const char *host, const char *port, struct addrinfo hints) 610 { 611 struct addrinfo *res, *res0; 612 int s, error, on = 1; 613 614 if ((error = getaddrinfo(host, port, &hints, &res))) 615 errx(1, "getaddrinfo: %s", gai_strerror(error)); 616 617 res0 = res; 618 do { 619 if ((s = socket(res0->ai_family, res0->ai_socktype, 620 res0->ai_protocol)) < 0) 621 continue; 622 #ifdef IPSEC 623 if (ipsec_policy[0] != NULL) 624 add_ipsec_policy(s, ipsec_policy[0]); 625 if (ipsec_policy[1] != NULL) 626 add_ipsec_policy(s, ipsec_policy[1]); 627 #endif 628 629 if (rtableid) { 630 if (setsockopt(s, SOL_SOCKET, SO_SETFIB, &rtableid, 631 sizeof(rtableid)) == -1) 632 err(1, "setsockopt(.., SO_SETFIB, %u, ..)", 633 rtableid); 634 } 635 636 /* Bind to a local port or source address if specified. */ 637 if (sflag || pflag) { 638 struct addrinfo ahints, *ares; 639 640 /* try IP_BINDANY, but don't insist */ 641 setsockopt(s, IPPROTO_IP, IP_BINDANY, &on, sizeof(on)); 642 memset(&ahints, 0, sizeof(struct addrinfo)); 643 ahints.ai_family = res0->ai_family; 644 ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 645 ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 646 ahints.ai_flags = AI_PASSIVE; 647 if ((error = getaddrinfo(sflag, pflag, &ahints, &ares))) 648 errx(1, "getaddrinfo: %s", gai_strerror(error)); 649 650 if (bind(s, (struct sockaddr *)ares->ai_addr, 651 ares->ai_addrlen) < 0) 652 errx(1, "bind failed: %s", strerror(errno)); 653 freeaddrinfo(ares); 654 } 655 656 set_common_sockopts(s); 657 658 if (timeout_connect(s, res0->ai_addr, res0->ai_addrlen) == 0) 659 break; 660 else if (vflag) 661 warn("connect to %s port %s (%s) failed", host, port, 662 uflag ? "udp" : "tcp"); 663 664 close(s); 665 s = -1; 666 } while ((res0 = res0->ai_next) != NULL); 667 668 freeaddrinfo(res); 669 670 return (s); 671 } 672 673 int 674 timeout_connect(int s, const struct sockaddr *name, socklen_t namelen) 675 { 676 struct pollfd pfd; 677 socklen_t optlen; 678 int flags, optval; 679 int ret; 680 681 if (timeout != -1) { 682 flags = fcntl(s, F_GETFL, 0); 683 if (fcntl(s, F_SETFL, flags | O_NONBLOCK) == -1) 684 err(1, "set non-blocking mode"); 685 } 686 687 if ((ret = connect(s, name, namelen)) != 0 && errno == EINPROGRESS) { 688 pfd.fd = s; 689 pfd.events = POLLOUT; 690 if ((ret = poll(&pfd, 1, timeout)) == 1) { 691 optlen = sizeof(optval); 692 if ((ret = getsockopt(s, SOL_SOCKET, SO_ERROR, 693 &optval, &optlen)) == 0) { 694 errno = optval; 695 ret = optval == 0 ? 0 : -1; 696 } 697 } else if (ret == 0) { 698 errno = ETIMEDOUT; 699 ret = -1; 700 } else 701 err(1, "poll failed"); 702 } 703 704 if (timeout != -1 && fcntl(s, F_SETFL, flags) == -1) 705 err(1, "restoring flags"); 706 707 return (ret); 708 } 709 710 /* 711 * local_listen() 712 * Returns a socket listening on a local port, binds to specified source 713 * address. Returns -1 on failure. 714 */ 715 int 716 local_listen(char *host, char *port, struct addrinfo hints) 717 { 718 struct addrinfo *res, *res0; 719 int s, ret, x = 1; 720 int error; 721 722 /* Allow nodename to be null. */ 723 hints.ai_flags |= AI_PASSIVE; 724 725 /* 726 * In the case of binding to a wildcard address 727 * default to binding to an ipv4 address. 728 */ 729 if (host == NULL && hints.ai_family == AF_UNSPEC) 730 hints.ai_family = AF_INET; 731 732 if ((error = getaddrinfo(host, port, &hints, &res))) 733 errx(1, "getaddrinfo: %s", gai_strerror(error)); 734 735 res0 = res; 736 do { 737 if ((s = socket(res0->ai_family, res0->ai_socktype, 738 res0->ai_protocol)) < 0) 739 continue; 740 741 if (rtableid) { 742 ret = setsockopt(s, SOL_SOCKET, SO_SETFIB, &rtableid, 743 sizeof(rtableid)); 744 if (ret == -1) 745 err(1, "setsockopt(.., SO_SETFIB, %u, ..)", 746 rtableid); 747 } 748 749 ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x)); 750 if (ret == -1) 751 err(1, NULL); 752 #ifdef IPSEC 753 if (ipsec_policy[0] != NULL) 754 add_ipsec_policy(s, ipsec_policy[0]); 755 if (ipsec_policy[1] != NULL) 756 add_ipsec_policy(s, ipsec_policy[1]); 757 #endif 758 if (FreeBSD_Oflag) { 759 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 760 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 761 err(1, "disable TCP options"); 762 } 763 764 if (bind(s, (struct sockaddr *)res0->ai_addr, 765 res0->ai_addrlen) == 0) 766 break; 767 768 close(s); 769 s = -1; 770 } while ((res0 = res0->ai_next) != NULL); 771 772 if (!uflag && s != -1) { 773 if (listen(s, 1) < 0) 774 err(1, "listen"); 775 } 776 777 freeaddrinfo(res); 778 779 return (s); 780 } 781 782 /* 783 * readwrite() 784 * Loop that polls on the network file descriptor and stdin. 785 */ 786 void 787 readwrite(int nfd) 788 { 789 struct pollfd pfd[2]; 790 unsigned char buf[16384]; 791 int n, wfd = fileno(stdin); 792 int lfd = fileno(stdout); 793 int plen; 794 795 plen = 2048; 796 797 /* Setup Network FD */ 798 pfd[0].fd = nfd; 799 pfd[0].events = POLLIN; 800 801 /* Set up STDIN FD. */ 802 pfd[1].fd = wfd; 803 pfd[1].events = POLLIN; 804 805 while (pfd[0].fd != -1) { 806 if (iflag) 807 sleep(iflag); 808 809 if ((n = poll(pfd, 2 - dflag, timeout)) < 0) { 810 close(nfd); 811 err(1, "Polling Error"); 812 } 813 814 if (n == 0) 815 return; 816 817 if (pfd[0].revents & POLLIN) { 818 if ((n = read(nfd, buf, plen)) < 0) 819 return; 820 else if (n == 0) { 821 shutdown(nfd, SHUT_RD); 822 pfd[0].fd = -1; 823 pfd[0].events = 0; 824 } else { 825 if (tflag) 826 atelnet(nfd, buf, n); 827 if (atomicio(vwrite, lfd, buf, n) != n) 828 return; 829 } 830 } 831 832 if (!dflag && pfd[1].revents & POLLIN) { 833 if ((n = read(wfd, buf, plen)) < 0) 834 return; 835 else if (n == 0) { 836 shutdown(nfd, SHUT_WR); 837 pfd[1].fd = -1; 838 pfd[1].events = 0; 839 } else { 840 if (atomicio(vwrite, nfd, buf, n) != n) 841 return; 842 } 843 } 844 } 845 } 846 847 /* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */ 848 void 849 atelnet(int nfd, unsigned char *buf, unsigned int size) 850 { 851 unsigned char *p, *end; 852 unsigned char obuf[4]; 853 854 if (size < 3) 855 return; 856 end = buf + size - 2; 857 858 for (p = buf; p < end; p++) { 859 if (*p != IAC) 860 continue; 861 862 obuf[0] = IAC; 863 p++; 864 if ((*p == WILL) || (*p == WONT)) 865 obuf[1] = DONT; 866 else if ((*p == DO) || (*p == DONT)) 867 obuf[1] = WONT; 868 else 869 continue; 870 871 p++; 872 obuf[2] = *p; 873 if (atomicio(vwrite, nfd, obuf, 3) != 3) 874 warn("Write Error!"); 875 } 876 } 877 878 /* 879 * build_ports() 880 * Build an array of ports in portlist[], listing each port 881 * that we should try to connect to. 882 */ 883 void 884 build_ports(char *p) 885 { 886 const char *errstr; 887 char *n; 888 int hi, lo, cp; 889 int x = 0; 890 891 if ((n = strchr(p, '-')) != NULL) { 892 *n = '\0'; 893 n++; 894 895 /* Make sure the ports are in order: lowest->highest. */ 896 hi = strtonum(n, 1, PORT_MAX, &errstr); 897 if (errstr) 898 errx(1, "port number %s: %s", errstr, n); 899 lo = strtonum(p, 1, PORT_MAX, &errstr); 900 if (errstr) 901 errx(1, "port number %s: %s", errstr, p); 902 903 if (lo > hi) { 904 cp = hi; 905 hi = lo; 906 lo = cp; 907 } 908 909 /* Load ports sequentially. */ 910 for (cp = lo; cp <= hi; cp++) { 911 portlist[x] = calloc(1, PORT_MAX_LEN); 912 if (portlist[x] == NULL) 913 err(1, NULL); 914 snprintf(portlist[x], PORT_MAX_LEN, "%d", cp); 915 x++; 916 } 917 918 /* Randomly swap ports. */ 919 if (rflag) { 920 int y; 921 char *c; 922 923 for (x = 0; x <= (hi - lo); x++) { 924 y = (arc4random() & 0xFFFF) % (hi - lo); 925 c = portlist[x]; 926 portlist[x] = portlist[y]; 927 portlist[y] = c; 928 } 929 } 930 } else { 931 hi = strtonum(p, 1, PORT_MAX, &errstr); 932 if (errstr) 933 errx(1, "port number %s: %s", errstr, p); 934 portlist[0] = strdup(p); 935 if (portlist[0] == NULL) 936 err(1, NULL); 937 } 938 } 939 940 /* 941 * udptest() 942 * Do a few writes to see if the UDP port is there. 943 * Fails once PF state table is full. 944 */ 945 int 946 udptest(int s) 947 { 948 int i, ret; 949 950 for (i = 0; i <= 3; i++) { 951 if (write(s, "X", 1) == 1) 952 ret = 1; 953 else 954 ret = -1; 955 } 956 return (ret); 957 } 958 959 void 960 set_common_sockopts(int s) 961 { 962 int x = 1; 963 964 if (Sflag) { 965 if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG, 966 &x, sizeof(x)) == -1) 967 err(1, NULL); 968 } 969 if (Dflag) { 970 if (setsockopt(s, SOL_SOCKET, SO_DEBUG, 971 &x, sizeof(x)) == -1) 972 err(1, NULL); 973 } 974 if (Tflag != -1) { 975 if (setsockopt(s, IPPROTO_IP, IP_TOS, 976 &Tflag, sizeof(Tflag)) == -1) 977 err(1, "set IP ToS"); 978 } 979 if (Iflag) { 980 if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, 981 &Iflag, sizeof(Iflag)) == -1) 982 err(1, "set TCP receive buffer size"); 983 } 984 if (Oflag) { 985 if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, 986 &Oflag, sizeof(Oflag)) == -1) 987 err(1, "set TCP send buffer size"); 988 } 989 if (FreeBSD_Oflag) { 990 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 991 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 992 err(1, "disable TCP options"); 993 } 994 } 995 996 int 997 map_tos(char *s, int *val) 998 { 999 /* DiffServ Codepoints and other TOS mappings */ 1000 const struct toskeywords { 1001 const char *keyword; 1002 int val; 1003 } *t, toskeywords[] = { 1004 { "af11", IPTOS_DSCP_AF11 }, 1005 { "af12", IPTOS_DSCP_AF12 }, 1006 { "af13", IPTOS_DSCP_AF13 }, 1007 { "af21", IPTOS_DSCP_AF21 }, 1008 { "af22", IPTOS_DSCP_AF22 }, 1009 { "af23", IPTOS_DSCP_AF23 }, 1010 { "af31", IPTOS_DSCP_AF31 }, 1011 { "af32", IPTOS_DSCP_AF32 }, 1012 { "af33", IPTOS_DSCP_AF33 }, 1013 { "af41", IPTOS_DSCP_AF41 }, 1014 { "af42", IPTOS_DSCP_AF42 }, 1015 { "af43", IPTOS_DSCP_AF43 }, 1016 { "critical", IPTOS_PREC_CRITIC_ECP }, 1017 { "cs0", IPTOS_DSCP_CS0 }, 1018 { "cs1", IPTOS_DSCP_CS1 }, 1019 { "cs2", IPTOS_DSCP_CS2 }, 1020 { "cs3", IPTOS_DSCP_CS3 }, 1021 { "cs4", IPTOS_DSCP_CS4 }, 1022 { "cs5", IPTOS_DSCP_CS5 }, 1023 { "cs6", IPTOS_DSCP_CS6 }, 1024 { "cs7", IPTOS_DSCP_CS7 }, 1025 { "ef", IPTOS_DSCP_EF }, 1026 { "inetcontrol", IPTOS_PREC_INTERNETCONTROL }, 1027 { "lowdelay", IPTOS_LOWDELAY }, 1028 { "netcontrol", IPTOS_PREC_NETCONTROL }, 1029 { "reliability", IPTOS_RELIABILITY }, 1030 { "throughput", IPTOS_THROUGHPUT }, 1031 { NULL, -1 }, 1032 }; 1033 1034 for (t = toskeywords; t->keyword != NULL; t++) { 1035 if (strcmp(s, t->keyword) == 0) { 1036 *val = t->val; 1037 return (1); 1038 } 1039 } 1040 1041 return (0); 1042 } 1043 1044 void 1045 report_connect(const struct sockaddr *sa, socklen_t salen) 1046 { 1047 char remote_host[NI_MAXHOST]; 1048 char remote_port[NI_MAXSERV]; 1049 int herr; 1050 int flags = NI_NUMERICSERV; 1051 1052 if (nflag) 1053 flags |= NI_NUMERICHOST; 1054 1055 if ((herr = getnameinfo(sa, salen, 1056 remote_host, sizeof(remote_host), 1057 remote_port, sizeof(remote_port), 1058 flags)) != 0) { 1059 if (herr == EAI_SYSTEM) 1060 err(1, "getnameinfo"); 1061 else 1062 errx(1, "getnameinfo: %s", gai_strerror(herr)); 1063 } 1064 1065 fprintf(stderr, 1066 "Connection from %s %s " 1067 "received!\n", remote_host, remote_port); 1068 } 1069 1070 void 1071 help(void) 1072 { 1073 usage(0); 1074 fprintf(stderr, "\tCommand Summary:\n\ 1075 \t-4 Use IPv4\n\ 1076 \t-6 Use IPv6\n\ 1077 \t-D Enable the debug socket option\n\ 1078 \t-d Detach from stdin\n"); 1079 #ifdef IPSEC 1080 fprintf(stderr, "\ 1081 \t-E Use IPsec ESP\n\ 1082 \t-e policy Use specified IPsec policy\n"); 1083 #endif 1084 fprintf(stderr, "\ 1085 \t-h This help text\n\ 1086 \t-I length TCP receive buffer length\n\ 1087 \t-i secs\t Delay interval for lines sent, ports scanned\n\ 1088 \t-k Keep inbound sockets open for multiple connects\n\ 1089 \t-l Listen mode, for inbound connects\n\ 1090 \t-n Suppress name/port resolutions\n\ 1091 \t--no-tcpopt Disable TCP options\n\ 1092 \t-O length TCP send buffer length\n\ 1093 \t-P proxyuser\tUsername for proxy authentication\n\ 1094 \t-p port\t Specify local port for remote connects\n\ 1095 \t-r Randomize remote ports\n\ 1096 \t-S Enable the TCP MD5 signature option\n\ 1097 \t-s addr\t Local source address\n\ 1098 \t-T toskeyword\tSet IP Type of Service\n\ 1099 \t-t Answer TELNET negotiation\n\ 1100 \t-U Use UNIX domain socket\n\ 1101 \t-u UDP mode\n\ 1102 \t-V rtable Specify alternate routing table\n\ 1103 \t-v Verbose\n\ 1104 \t-w secs\t Timeout for connects and final net reads\n\ 1105 \t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\ 1106 \t-x addr[:port]\tSpecify proxy address and port\n\ 1107 \t-z Zero-I/O mode [used for scanning]\n\ 1108 Port numbers can be individual or ranges: lo-hi [inclusive]\n"); 1109 #ifdef IPSEC 1110 fprintf(stderr, "See ipsec_set_policy(3) for -e argument format\n"); 1111 #endif 1112 exit(1); 1113 } 1114 1115 #ifdef IPSEC 1116 void 1117 add_ipsec_policy(int s, char *policy) 1118 { 1119 char *raw; 1120 int e; 1121 1122 raw = ipsec_set_policy(policy, strlen(policy)); 1123 if (raw == NULL) 1124 errx(1, "ipsec_set_policy `%s': %s", policy, 1125 ipsec_strerror()); 1126 e = setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, raw, 1127 ipsec_get_policylen(raw)); 1128 if (e < 0) 1129 err(1, "ipsec policy cannot be configured"); 1130 free(raw); 1131 if (vflag) 1132 fprintf(stderr, "ipsec policy configured: `%s'\n", policy); 1133 return; 1134 } 1135 #endif /* IPSEC */ 1136 1137 void 1138 usage(int ret) 1139 { 1140 fprintf(stderr, 1141 #ifdef IPSEC 1142 "usage: nc [-46DdEhklnrStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n" 1143 #else 1144 "usage: nc [-46DdhklnrStUuvz] [-I length] [-i interval] [-O length]\n" 1145 #endif 1146 "\t [-P proxy_username] [-p source_port] [-s source] [-T ToS]\n" 1147 "\t [-V rtable] [-w timeout] [-X proxy_protocol]\n" 1148 "\t [-x proxy_address[:port]] [destination] [port]\n"); 1149 if (ret) 1150 exit(1); 1151 } 1152