1 /* $OpenBSD: netcat.c,v 1.122 2014/07/20 01:38:40 guenther 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/uio.h> 42 #include <sys/un.h> 43 44 #include <netinet/in.h> 45 #include <netinet/in_systm.h> 46 #ifdef IPSEC 47 #include <netipsec/ipsec.h> 48 #endif 49 #include <netinet/tcp.h> 50 #include <netinet/ip.h> 51 #include <arpa/telnet.h> 52 53 #include <err.h> 54 #include <errno.h> 55 #include <getopt.h> 56 #include <netdb.h> 57 #include <poll.h> 58 #include <stdarg.h> 59 #include <stdio.h> 60 #include <stdlib.h> 61 #include <string.h> 62 #include <unistd.h> 63 #include <fcntl.h> 64 #include <limits.h> 65 #include "atomicio.h" 66 67 #ifndef SUN_LEN 68 #define SUN_LEN(su) \ 69 (sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path)) 70 #endif 71 72 #define PORT_MAX 65535 73 #define PORT_MAX_LEN 6 74 #define UNIX_DG_TMP_SOCKET_SIZE 19 75 76 /* Command Line Options */ 77 int dflag; /* detached, no stdin */ 78 int Fflag; /* fdpass sock to stdout */ 79 unsigned int iflag; /* Interval Flag */ 80 int kflag; /* More than one connect */ 81 int lflag; /* Bind to local port */ 82 int Nflag; /* shutdown() network socket */ 83 int nflag; /* Don't do name look up */ 84 int FreeBSD_Oflag; /* Do not use TCP options */ 85 char *Pflag; /* Proxy username */ 86 char *pflag; /* Localport flag */ 87 int rflag; /* Random ports flag */ 88 char *sflag; /* Source Address */ 89 int tflag; /* Telnet Emulation */ 90 int uflag; /* UDP - Default to TCP */ 91 int vflag; /* Verbosity */ 92 int xflag; /* Socks proxy */ 93 int zflag; /* Port Scan Flag */ 94 int Dflag; /* sodebug */ 95 int Iflag; /* TCP receive buffer size */ 96 int Oflag; /* TCP send buffer size */ 97 int Sflag; /* TCP MD5 signature option */ 98 int Tflag = -1; /* IP Type of Service */ 99 int rtableid = -1; 100 101 int timeout = -1; 102 int family = AF_UNSPEC; 103 char *portlist[PORT_MAX+1]; 104 char *unix_dg_tmp_socket; 105 106 void atelnet(int, unsigned char *, unsigned int); 107 void build_ports(char *); 108 void help(void); 109 int local_listen(char *, char *, struct addrinfo); 110 void readwrite(int); 111 void fdpass(int nfd) __attribute__((noreturn)); 112 int remote_connect(const char *, const char *, struct addrinfo); 113 int timeout_connect(int, const struct sockaddr *, socklen_t); 114 int socks_connect(const char *, const char *, struct addrinfo, 115 const char *, const char *, struct addrinfo, int, const char *); 116 int udptest(int); 117 int unix_bind(char *); 118 int unix_connect(char *); 119 int unix_listen(char *); 120 void set_common_sockopts(int); 121 int map_tos(char *, int *); 122 void report_connect(const struct sockaddr *, socklen_t); 123 void usage(int); 124 125 #ifdef IPSEC 126 void add_ipsec_policy(int, char *); 127 128 char *ipsec_policy[2]; 129 #endif 130 131 int 132 main(int argc, char *argv[]) 133 { 134 int ch, s, ret, socksv, ipsec_count; 135 int numfibs; 136 size_t intsize = sizeof(int); 137 char *host, *uport; 138 struct addrinfo hints; 139 struct servent *sv; 140 socklen_t len; 141 struct sockaddr_storage cliaddr; 142 char *proxy; 143 const char *errstr, *proxyhost = "", *proxyport = NULL; 144 struct addrinfo proxyhints; 145 char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE]; 146 struct option longopts[] = { 147 { "no-tcpopt", no_argument, &FreeBSD_Oflag, 1 }, 148 { NULL, 0, NULL, 0 } 149 }; 150 151 ret = 1; 152 ipsec_count = 0; 153 s = 0; 154 socksv = 5; 155 host = NULL; 156 uport = NULL; 157 sv = NULL; 158 159 while ((ch = getopt_long(argc, argv, 160 "46DdEe:FhI:i:klNnoO:P:p:rSs:tT:UuV:vw:X:x:z", 161 longopts, NULL)) != -1) { 162 switch (ch) { 163 case '4': 164 family = AF_INET; 165 break; 166 case '6': 167 family = AF_INET6; 168 break; 169 case 'U': 170 family = AF_UNIX; 171 break; 172 case 'X': 173 if (strcasecmp(optarg, "connect") == 0) 174 socksv = -1; /* HTTP proxy CONNECT */ 175 else if (strcmp(optarg, "4") == 0) 176 socksv = 4; /* SOCKS v.4 */ 177 else if (strcmp(optarg, "5") == 0) 178 socksv = 5; /* SOCKS v.5 */ 179 else 180 errx(1, "unsupported proxy protocol"); 181 break; 182 case 'd': 183 dflag = 1; 184 break; 185 case 'e': 186 #ifdef IPSEC 187 ipsec_policy[ipsec_count++ % 2] = optarg; 188 #else 189 errx(1, "IPsec support unavailable."); 190 #endif 191 break; 192 case 'E': 193 #ifdef IPSEC 194 ipsec_policy[0] = "in ipsec esp/transport//require"; 195 ipsec_policy[1] = "out ipsec esp/transport//require"; 196 #else 197 errx(1, "IPsec support unavailable."); 198 #endif 199 break; 200 case 'F': 201 Fflag = 1; 202 break; 203 case 'h': 204 help(); 205 break; 206 case 'i': 207 iflag = strtonum(optarg, 0, UINT_MAX, &errstr); 208 if (errstr) 209 errx(1, "interval %s: %s", errstr, optarg); 210 break; 211 case 'k': 212 kflag = 1; 213 break; 214 case 'l': 215 lflag = 1; 216 break; 217 case 'N': 218 Nflag = 1; 219 break; 220 case 'n': 221 nflag = 1; 222 break; 223 case 'o': 224 fprintf(stderr, "option -o is deprecated.\n"); 225 break; 226 case 'P': 227 Pflag = optarg; 228 break; 229 case 'p': 230 pflag = optarg; 231 break; 232 case 'r': 233 rflag = 1; 234 break; 235 case 's': 236 sflag = optarg; 237 break; 238 case 't': 239 tflag = 1; 240 break; 241 case 'u': 242 uflag = 1; 243 break; 244 case 'V': 245 if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1) 246 errx(1, "Multiple FIBS not supported"); 247 rtableid = (int)strtonum(optarg, 0, 248 numfibs - 1, &errstr); 249 if (errstr) 250 errx(1, "rtable %s: %s", errstr, optarg); 251 break; 252 case 'v': 253 vflag = 1; 254 break; 255 case 'w': 256 timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr); 257 if (errstr) 258 errx(1, "timeout %s: %s", errstr, optarg); 259 timeout *= 1000; 260 break; 261 case 'x': 262 xflag = 1; 263 if ((proxy = strdup(optarg)) == NULL) 264 err(1, NULL); 265 break; 266 case 'z': 267 zflag = 1; 268 break; 269 case 'D': 270 Dflag = 1; 271 break; 272 case 'I': 273 Iflag = strtonum(optarg, 1, 65536 << 14, &errstr); 274 if (errstr != NULL) 275 errx(1, "TCP receive window %s: %s", 276 errstr, optarg); 277 break; 278 case 'O': 279 Oflag = strtonum(optarg, 1, 65536 << 14, &errstr); 280 if (errstr != NULL) { 281 if (strcmp(errstr, "invalid") != 0) 282 errx(1, "TCP send window %s: %s", 283 errstr, optarg); 284 } 285 break; 286 case 'S': 287 Sflag = 1; 288 break; 289 case 'T': 290 errstr = NULL; 291 errno = 0; 292 if (map_tos(optarg, &Tflag)) 293 break; 294 if (strlen(optarg) > 1 && optarg[0] == '0' && 295 optarg[1] == 'x') 296 Tflag = (int)strtol(optarg, NULL, 16); 297 else 298 Tflag = (int)strtonum(optarg, 0, 255, 299 &errstr); 300 if (Tflag < 0 || Tflag > 255 || errstr || errno) 301 errx(1, "illegal tos value %s", optarg); 302 break; 303 default: 304 usage(1); 305 } 306 } 307 argc -= optind; 308 argv += optind; 309 310 /* Cruft to make sure options are clean, and used properly. */ 311 if (argv[0] && !argv[1] && family == AF_UNIX) { 312 host = argv[0]; 313 uport = NULL; 314 } else if (argv[0] && !argv[1]) { 315 if (!lflag) 316 usage(1); 317 uport = argv[0]; 318 host = NULL; 319 } else if (argv[0] && argv[1]) { 320 host = argv[0]; 321 uport = argv[1]; 322 } else 323 usage(1); 324 325 if (lflag && sflag) 326 errx(1, "cannot use -s and -l"); 327 if (lflag && pflag) 328 errx(1, "cannot use -p and -l"); 329 if (lflag && zflag) 330 errx(1, "cannot use -z and -l"); 331 if (!lflag && kflag) 332 errx(1, "must use -l with -k"); 333 334 /* Get name of temporary socket for unix datagram client */ 335 if ((family == AF_UNIX) && uflag && !lflag) { 336 if (sflag) { 337 unix_dg_tmp_socket = sflag; 338 } else { 339 strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX", 340 UNIX_DG_TMP_SOCKET_SIZE); 341 if (mktemp(unix_dg_tmp_socket_buf) == NULL) 342 err(1, "mktemp"); 343 unix_dg_tmp_socket = unix_dg_tmp_socket_buf; 344 } 345 } 346 347 /* Initialize addrinfo structure. */ 348 if (family != AF_UNIX) { 349 memset(&hints, 0, sizeof(struct addrinfo)); 350 hints.ai_family = family; 351 hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 352 hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 353 if (nflag) 354 hints.ai_flags |= AI_NUMERICHOST; 355 } 356 357 if (xflag) { 358 if (uflag) 359 errx(1, "no proxy support for UDP mode"); 360 361 if (lflag) 362 errx(1, "no proxy support for listen"); 363 364 if (family == AF_UNIX) 365 errx(1, "no proxy support for unix sockets"); 366 367 /* XXX IPv6 transport to proxy would probably work */ 368 if (family == AF_INET6) 369 errx(1, "no proxy support for IPv6"); 370 371 if (sflag) 372 errx(1, "no proxy support for local source address"); 373 374 proxyhost = strsep(&proxy, ":"); 375 proxyport = proxy; 376 377 memset(&proxyhints, 0, sizeof(struct addrinfo)); 378 proxyhints.ai_family = family; 379 proxyhints.ai_socktype = SOCK_STREAM; 380 proxyhints.ai_protocol = IPPROTO_TCP; 381 if (nflag) 382 proxyhints.ai_flags |= AI_NUMERICHOST; 383 } 384 385 if (lflag) { 386 int connfd; 387 ret = 0; 388 389 if (family == AF_UNIX) { 390 if (uflag) 391 s = unix_bind(host); 392 else 393 s = unix_listen(host); 394 } 395 396 /* Allow only one connection at a time, but stay alive. */ 397 for (;;) { 398 if (family != AF_UNIX) 399 s = local_listen(host, uport, hints); 400 if (s < 0) 401 err(1, NULL); 402 /* 403 * For UDP and -k, don't connect the socket, let it 404 * receive datagrams from multiple socket pairs. 405 */ 406 if (uflag && kflag) 407 readwrite(s); 408 /* 409 * For UDP and not -k, we will use recvfrom() initially 410 * to wait for a caller, then use the regular functions 411 * to talk to the caller. 412 */ 413 else if (uflag && !kflag) { 414 int rv, plen; 415 char buf[16384]; 416 struct sockaddr_storage z; 417 418 len = sizeof(z); 419 plen = 2048; 420 rv = recvfrom(s, buf, plen, MSG_PEEK, 421 (struct sockaddr *)&z, &len); 422 if (rv < 0) 423 err(1, "recvfrom"); 424 425 rv = connect(s, (struct sockaddr *)&z, len); 426 if (rv < 0) 427 err(1, "connect"); 428 429 if (vflag) 430 report_connect((struct sockaddr *)&z, len); 431 432 readwrite(s); 433 } else { 434 len = sizeof(cliaddr); 435 connfd = accept(s, (struct sockaddr *)&cliaddr, 436 &len); 437 if (connfd == -1) { 438 /* For now, all errnos are fatal */ 439 err(1, "accept"); 440 } 441 if (vflag) 442 report_connect((struct sockaddr *)&cliaddr, len); 443 444 readwrite(connfd); 445 close(connfd); 446 } 447 448 if (family != AF_UNIX) 449 close(s); 450 else if (uflag) { 451 if (connect(s, NULL, 0) < 0) 452 err(1, "connect"); 453 } 454 455 if (!kflag) 456 break; 457 } 458 } else if (family == AF_UNIX) { 459 ret = 0; 460 461 if ((s = unix_connect(host)) > 0 && !zflag) { 462 readwrite(s); 463 close(s); 464 } else 465 ret = 1; 466 467 if (uflag) 468 unlink(unix_dg_tmp_socket); 469 exit(ret); 470 471 } else { 472 int i = 0; 473 474 /* Construct the portlist[] array. */ 475 build_ports(uport); 476 477 /* Cycle through portlist, connecting to each port. */ 478 for (i = 0; portlist[i] != NULL; i++) { 479 if (s) 480 close(s); 481 482 if (xflag) 483 s = socks_connect(host, portlist[i], hints, 484 proxyhost, proxyport, proxyhints, socksv, 485 Pflag); 486 else 487 s = remote_connect(host, portlist[i], hints); 488 489 if (s < 0) 490 continue; 491 492 ret = 0; 493 if (vflag || zflag) { 494 /* For UDP, make sure we are connected. */ 495 if (uflag) { 496 if (udptest(s) == -1) { 497 ret = 1; 498 continue; 499 } 500 } 501 502 /* Don't look up port if -n. */ 503 if (nflag) 504 sv = NULL; 505 else { 506 sv = getservbyport( 507 ntohs(atoi(portlist[i])), 508 uflag ? "udp" : "tcp"); 509 } 510 511 fprintf(stderr, 512 "Connection to %s %s port [%s/%s] " 513 "succeeded!\n", host, portlist[i], 514 uflag ? "udp" : "tcp", 515 sv ? sv->s_name : "*"); 516 } 517 if (Fflag) 518 fdpass(s); 519 else if (!zflag) 520 readwrite(s); 521 } 522 } 523 524 if (s) 525 close(s); 526 527 exit(ret); 528 } 529 530 /* 531 * unix_bind() 532 * Returns a unix socket bound to the given path 533 */ 534 int 535 unix_bind(char *path) 536 { 537 struct sockaddr_un sun; 538 int s; 539 540 /* Create unix domain socket. */ 541 if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM, 542 0)) < 0) 543 return (-1); 544 545 memset(&sun, 0, sizeof(struct sockaddr_un)); 546 sun.sun_family = AF_UNIX; 547 548 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 549 sizeof(sun.sun_path)) { 550 close(s); 551 errno = ENAMETOOLONG; 552 return (-1); 553 } 554 555 if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 556 close(s); 557 return (-1); 558 } 559 return (s); 560 } 561 562 /* 563 * unix_connect() 564 * Returns a socket connected to a local unix socket. Returns -1 on failure. 565 */ 566 int 567 unix_connect(char *path) 568 { 569 struct sockaddr_un sun; 570 int s; 571 572 if (uflag) { 573 if ((s = unix_bind(unix_dg_tmp_socket)) < 0) 574 return (-1); 575 } else { 576 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 577 return (-1); 578 } 579 (void)fcntl(s, F_SETFD, FD_CLOEXEC); 580 581 memset(&sun, 0, sizeof(struct sockaddr_un)); 582 sun.sun_family = AF_UNIX; 583 584 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 585 sizeof(sun.sun_path)) { 586 close(s); 587 errno = ENAMETOOLONG; 588 return (-1); 589 } 590 if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 591 close(s); 592 return (-1); 593 } 594 return (s); 595 596 } 597 598 /* 599 * unix_listen() 600 * Create a unix domain socket, and listen on it. 601 */ 602 int 603 unix_listen(char *path) 604 { 605 int s; 606 if ((s = unix_bind(path)) < 0) 607 return (-1); 608 609 if (listen(s, 5) < 0) { 610 close(s); 611 return (-1); 612 } 613 return (s); 614 } 615 616 /* 617 * remote_connect() 618 * Returns a socket connected to a remote host. Properly binds to a local 619 * port or source address if needed. Returns -1 on failure. 620 */ 621 int 622 remote_connect(const char *host, const char *port, struct addrinfo hints) 623 { 624 struct addrinfo *res, *res0; 625 int s, error, on = 1; 626 627 if ((error = getaddrinfo(host, port, &hints, &res))) 628 errx(1, "getaddrinfo: %s", gai_strerror(error)); 629 630 res0 = res; 631 do { 632 if ((s = socket(res0->ai_family, res0->ai_socktype, 633 res0->ai_protocol)) < 0) 634 continue; 635 #ifdef IPSEC 636 if (ipsec_policy[0] != NULL) 637 add_ipsec_policy(s, ipsec_policy[0]); 638 if (ipsec_policy[1] != NULL) 639 add_ipsec_policy(s, ipsec_policy[1]); 640 #endif 641 642 if (rtableid >= 0 && (setsockopt(s, SOL_SOCKET, SO_SETFIB, 643 &rtableid, sizeof(rtableid)) == -1)) 644 err(1, "setsockopt SO_SETFIB"); 645 646 /* Bind to a local port or source address if specified. */ 647 if (sflag || pflag) { 648 struct addrinfo ahints, *ares; 649 650 /* try IP_BINDANY, but don't insist */ 651 setsockopt(s, IPPROTO_IP, IP_BINDANY, &on, sizeof(on)); 652 memset(&ahints, 0, sizeof(struct addrinfo)); 653 ahints.ai_family = res0->ai_family; 654 ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 655 ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 656 ahints.ai_flags = AI_PASSIVE; 657 if ((error = getaddrinfo(sflag, pflag, &ahints, &ares))) 658 errx(1, "getaddrinfo: %s", gai_strerror(error)); 659 660 if (bind(s, (struct sockaddr *)ares->ai_addr, 661 ares->ai_addrlen) < 0) 662 err(1, "bind failed"); 663 freeaddrinfo(ares); 664 } 665 666 set_common_sockopts(s); 667 668 if (timeout_connect(s, res0->ai_addr, res0->ai_addrlen) == 0) 669 break; 670 else if (vflag) 671 warn("connect to %s port %s (%s) failed", host, port, 672 uflag ? "udp" : "tcp"); 673 674 close(s); 675 s = -1; 676 } while ((res0 = res0->ai_next) != NULL); 677 678 freeaddrinfo(res); 679 680 return (s); 681 } 682 683 int 684 timeout_connect(int s, const struct sockaddr *name, socklen_t namelen) 685 { 686 struct pollfd pfd; 687 socklen_t optlen; 688 int flags, optval; 689 int ret; 690 691 if (timeout != -1) { 692 flags = fcntl(s, F_GETFL, 0); 693 if (fcntl(s, F_SETFL, flags | O_NONBLOCK) == -1) 694 err(1, "set non-blocking mode"); 695 } 696 697 if ((ret = connect(s, name, namelen)) != 0 && errno == EINPROGRESS) { 698 pfd.fd = s; 699 pfd.events = POLLOUT; 700 if ((ret = poll(&pfd, 1, timeout)) == 1) { 701 optlen = sizeof(optval); 702 if ((ret = getsockopt(s, SOL_SOCKET, SO_ERROR, 703 &optval, &optlen)) == 0) { 704 errno = optval; 705 ret = optval == 0 ? 0 : -1; 706 } 707 } else if (ret == 0) { 708 errno = ETIMEDOUT; 709 ret = -1; 710 } else 711 err(1, "poll failed"); 712 } 713 714 if (timeout != -1 && fcntl(s, F_SETFL, flags) == -1) 715 err(1, "restoring flags"); 716 717 return (ret); 718 } 719 720 /* 721 * local_listen() 722 * Returns a socket listening on a local port, binds to specified source 723 * address. Returns -1 on failure. 724 */ 725 int 726 local_listen(char *host, char *port, struct addrinfo hints) 727 { 728 struct addrinfo *res, *res0; 729 int s, ret, x = 1; 730 int error; 731 732 /* Allow nodename to be null. */ 733 hints.ai_flags |= AI_PASSIVE; 734 735 /* 736 * In the case of binding to a wildcard address 737 * default to binding to an ipv4 address. 738 */ 739 if (host == NULL && hints.ai_family == AF_UNSPEC) 740 hints.ai_family = AF_INET; 741 742 if ((error = getaddrinfo(host, port, &hints, &res))) 743 errx(1, "getaddrinfo: %s", gai_strerror(error)); 744 745 res0 = res; 746 do { 747 if ((s = socket(res0->ai_family, res0->ai_socktype, 748 res0->ai_protocol)) < 0) 749 continue; 750 751 if (rtableid >= 0 && (setsockopt(s, SOL_SOCKET, SO_SETFIB, 752 &rtableid, sizeof(rtableid)) == -1)) 753 err(1, "setsockopt SO_SETFIB"); 754 755 ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x)); 756 if (ret == -1) 757 err(1, NULL); 758 #ifdef IPSEC 759 if (ipsec_policy[0] != NULL) 760 add_ipsec_policy(s, ipsec_policy[0]); 761 if (ipsec_policy[1] != NULL) 762 add_ipsec_policy(s, ipsec_policy[1]); 763 #endif 764 if (FreeBSD_Oflag) { 765 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 766 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 767 err(1, "disable TCP options"); 768 } 769 770 if (bind(s, (struct sockaddr *)res0->ai_addr, 771 res0->ai_addrlen) == 0) 772 break; 773 774 close(s); 775 s = -1; 776 } while ((res0 = res0->ai_next) != NULL); 777 778 if (!uflag && s != -1) { 779 if (listen(s, 1) < 0) 780 err(1, "listen"); 781 } 782 783 freeaddrinfo(res); 784 785 return (s); 786 } 787 788 /* 789 * readwrite() 790 * Loop that polls on the network file descriptor and stdin. 791 */ 792 void 793 readwrite(int nfd) 794 { 795 struct pollfd pfd[2]; 796 unsigned char buf[16 * 1024]; 797 int n, wfd = fileno(stdin); 798 int lfd = fileno(stdout); 799 int plen; 800 801 plen = sizeof(buf); 802 803 /* Setup Network FD */ 804 pfd[0].fd = nfd; 805 pfd[0].events = POLLIN; 806 807 /* Set up STDIN FD. */ 808 pfd[1].fd = wfd; 809 pfd[1].events = POLLIN; 810 811 while (pfd[0].fd != -1) { 812 if (iflag) 813 sleep(iflag); 814 815 if ((n = poll(pfd, 2 - dflag, timeout)) < 0) { 816 int saved_errno = errno; 817 close(nfd); 818 errc(1, saved_errno, "Polling Error"); 819 } 820 821 if (n == 0) 822 return; 823 824 if (pfd[0].revents & POLLIN) { 825 if ((n = read(nfd, buf, plen)) < 0) 826 return; 827 else if (n == 0) { 828 shutdown(nfd, SHUT_RD); 829 pfd[0].fd = -1; 830 pfd[0].events = 0; 831 } else { 832 if (tflag) 833 atelnet(nfd, buf, n); 834 if (atomicio(vwrite, lfd, buf, n) != n) 835 return; 836 } 837 } 838 839 if (!dflag && pfd[1].revents & POLLIN) { 840 if ((n = read(wfd, buf, plen)) < 0) 841 return; 842 else if (n == 0) { 843 if (Nflag) 844 shutdown(nfd, SHUT_WR); 845 pfd[1].fd = -1; 846 pfd[1].events = 0; 847 } else { 848 if (atomicio(vwrite, nfd, buf, n) != n) 849 return; 850 } 851 } 852 } 853 } 854 855 /* 856 * fdpass() 857 * Pass the connected file descriptor to stdout and exit. 858 */ 859 void 860 fdpass(int nfd) 861 { 862 struct msghdr mh; 863 union { 864 struct cmsghdr hdr; 865 char buf[CMSG_SPACE(sizeof(int))]; 866 } cmsgbuf; 867 struct cmsghdr *cmsg; 868 struct iovec iov; 869 char c = '\0'; 870 ssize_t r; 871 struct pollfd pfd; 872 873 /* Avoid obvious stupidity */ 874 if (isatty(STDOUT_FILENO)) 875 errx(1, "Cannot pass file descriptor to tty"); 876 877 bzero(&mh, sizeof(mh)); 878 bzero(&cmsgbuf, sizeof(cmsgbuf)); 879 bzero(&iov, sizeof(iov)); 880 bzero(&pfd, sizeof(pfd)); 881 882 mh.msg_control = (caddr_t)&cmsgbuf.buf; 883 mh.msg_controllen = sizeof(cmsgbuf.buf); 884 cmsg = CMSG_FIRSTHDR(&mh); 885 cmsg->cmsg_len = CMSG_LEN(sizeof(int)); 886 cmsg->cmsg_level = SOL_SOCKET; 887 cmsg->cmsg_type = SCM_RIGHTS; 888 *(int *)CMSG_DATA(cmsg) = nfd; 889 890 iov.iov_base = &c; 891 iov.iov_len = 1; 892 mh.msg_iov = &iov; 893 mh.msg_iovlen = 1; 894 895 bzero(&pfd, sizeof(pfd)); 896 pfd.fd = STDOUT_FILENO; 897 for (;;) { 898 r = sendmsg(STDOUT_FILENO, &mh, 0); 899 if (r == -1) { 900 if (errno == EAGAIN || errno == EINTR) { 901 pfd.events = POLLOUT; 902 if (poll(&pfd, 1, -1) == -1) 903 err(1, "poll"); 904 continue; 905 } 906 err(1, "sendmsg"); 907 } else if (r == -1) 908 errx(1, "sendmsg: unexpected return value %zd", r); 909 else 910 break; 911 } 912 exit(0); 913 } 914 915 /* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */ 916 void 917 atelnet(int nfd, unsigned char *buf, unsigned int size) 918 { 919 unsigned char *p, *end; 920 unsigned char obuf[4]; 921 922 if (size < 3) 923 return; 924 end = buf + size - 2; 925 926 for (p = buf; p < end; p++) { 927 if (*p != IAC) 928 continue; 929 930 obuf[0] = IAC; 931 p++; 932 if ((*p == WILL) || (*p == WONT)) 933 obuf[1] = DONT; 934 else if ((*p == DO) || (*p == DONT)) 935 obuf[1] = WONT; 936 else 937 continue; 938 939 p++; 940 obuf[2] = *p; 941 if (atomicio(vwrite, nfd, obuf, 3) != 3) 942 warn("Write Error!"); 943 } 944 } 945 946 /* 947 * build_ports() 948 * Build an array of ports in portlist[], listing each port 949 * that we should try to connect to. 950 */ 951 void 952 build_ports(char *p) 953 { 954 const char *errstr; 955 char *n; 956 int hi, lo, cp; 957 int x = 0; 958 959 if ((n = strchr(p, '-')) != NULL) { 960 *n = '\0'; 961 n++; 962 963 /* Make sure the ports are in order: lowest->highest. */ 964 hi = strtonum(n, 1, PORT_MAX, &errstr); 965 if (errstr) 966 errx(1, "port number %s: %s", errstr, n); 967 lo = strtonum(p, 1, PORT_MAX, &errstr); 968 if (errstr) 969 errx(1, "port number %s: %s", errstr, p); 970 971 if (lo > hi) { 972 cp = hi; 973 hi = lo; 974 lo = cp; 975 } 976 977 /* Load ports sequentially. */ 978 for (cp = lo; cp <= hi; cp++) { 979 portlist[x] = calloc(1, PORT_MAX_LEN); 980 if (portlist[x] == NULL) 981 err(1, NULL); 982 snprintf(portlist[x], PORT_MAX_LEN, "%d", cp); 983 x++; 984 } 985 986 /* Randomly swap ports. */ 987 if (rflag) { 988 int y; 989 char *c; 990 991 for (x = 0; x <= (hi - lo); x++) { 992 y = (arc4random() & 0xFFFF) % (hi - lo); 993 c = portlist[x]; 994 portlist[x] = portlist[y]; 995 portlist[y] = c; 996 } 997 } 998 } else { 999 hi = strtonum(p, 1, PORT_MAX, &errstr); 1000 if (errstr) 1001 errx(1, "port number %s: %s", errstr, p); 1002 portlist[0] = strdup(p); 1003 if (portlist[0] == NULL) 1004 err(1, NULL); 1005 } 1006 } 1007 1008 /* 1009 * udptest() 1010 * Do a few writes to see if the UDP port is there. 1011 * Fails once PF state table is full. 1012 */ 1013 int 1014 udptest(int s) 1015 { 1016 int i, ret; 1017 1018 for (i = 0; i <= 3; i++) { 1019 if (write(s, "X", 1) == 1) 1020 ret = 1; 1021 else 1022 ret = -1; 1023 } 1024 return (ret); 1025 } 1026 1027 void 1028 set_common_sockopts(int s) 1029 { 1030 int x = 1; 1031 1032 if (Sflag) { 1033 if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG, 1034 &x, sizeof(x)) == -1) 1035 err(1, NULL); 1036 } 1037 if (Dflag) { 1038 if (setsockopt(s, SOL_SOCKET, SO_DEBUG, 1039 &x, sizeof(x)) == -1) 1040 err(1, NULL); 1041 } 1042 if (Tflag != -1) { 1043 if (setsockopt(s, IPPROTO_IP, IP_TOS, 1044 &Tflag, sizeof(Tflag)) == -1) 1045 err(1, "set IP ToS"); 1046 } 1047 if (Iflag) { 1048 if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, 1049 &Iflag, sizeof(Iflag)) == -1) 1050 err(1, "set TCP receive buffer size"); 1051 } 1052 if (Oflag) { 1053 if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, 1054 &Oflag, sizeof(Oflag)) == -1) 1055 err(1, "set TCP send buffer size"); 1056 } 1057 if (FreeBSD_Oflag) { 1058 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 1059 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 1060 err(1, "disable TCP options"); 1061 } 1062 } 1063 1064 int 1065 map_tos(char *s, int *val) 1066 { 1067 /* DiffServ Codepoints and other TOS mappings */ 1068 const struct toskeywords { 1069 const char *keyword; 1070 int val; 1071 } *t, toskeywords[] = { 1072 { "af11", IPTOS_DSCP_AF11 }, 1073 { "af12", IPTOS_DSCP_AF12 }, 1074 { "af13", IPTOS_DSCP_AF13 }, 1075 { "af21", IPTOS_DSCP_AF21 }, 1076 { "af22", IPTOS_DSCP_AF22 }, 1077 { "af23", IPTOS_DSCP_AF23 }, 1078 { "af31", IPTOS_DSCP_AF31 }, 1079 { "af32", IPTOS_DSCP_AF32 }, 1080 { "af33", IPTOS_DSCP_AF33 }, 1081 { "af41", IPTOS_DSCP_AF41 }, 1082 { "af42", IPTOS_DSCP_AF42 }, 1083 { "af43", IPTOS_DSCP_AF43 }, 1084 { "critical", IPTOS_PREC_CRITIC_ECP }, 1085 { "cs0", IPTOS_DSCP_CS0 }, 1086 { "cs1", IPTOS_DSCP_CS1 }, 1087 { "cs2", IPTOS_DSCP_CS2 }, 1088 { "cs3", IPTOS_DSCP_CS3 }, 1089 { "cs4", IPTOS_DSCP_CS4 }, 1090 { "cs5", IPTOS_DSCP_CS5 }, 1091 { "cs6", IPTOS_DSCP_CS6 }, 1092 { "cs7", IPTOS_DSCP_CS7 }, 1093 { "ef", IPTOS_DSCP_EF }, 1094 { "inetcontrol", IPTOS_PREC_INTERNETCONTROL }, 1095 { "lowdelay", IPTOS_LOWDELAY }, 1096 { "netcontrol", IPTOS_PREC_NETCONTROL }, 1097 { "reliability", IPTOS_RELIABILITY }, 1098 { "throughput", IPTOS_THROUGHPUT }, 1099 { NULL, -1 }, 1100 }; 1101 1102 for (t = toskeywords; t->keyword != NULL; t++) { 1103 if (strcmp(s, t->keyword) == 0) { 1104 *val = t->val; 1105 return (1); 1106 } 1107 } 1108 1109 return (0); 1110 } 1111 1112 void 1113 report_connect(const struct sockaddr *sa, socklen_t salen) 1114 { 1115 char remote_host[NI_MAXHOST]; 1116 char remote_port[NI_MAXSERV]; 1117 int herr; 1118 int flags = NI_NUMERICSERV; 1119 1120 if (nflag) 1121 flags |= NI_NUMERICHOST; 1122 1123 if ((herr = getnameinfo(sa, salen, 1124 remote_host, sizeof(remote_host), 1125 remote_port, sizeof(remote_port), 1126 flags)) != 0) { 1127 if (herr == EAI_SYSTEM) 1128 err(1, "getnameinfo"); 1129 else 1130 errx(1, "getnameinfo: %s", gai_strerror(herr)); 1131 } 1132 1133 fprintf(stderr, 1134 "Connection from %s %s " 1135 "received!\n", remote_host, remote_port); 1136 } 1137 1138 void 1139 help(void) 1140 { 1141 usage(0); 1142 fprintf(stderr, "\tCommand Summary:\n\ 1143 \t-4 Use IPv4\n\ 1144 \t-6 Use IPv6\n\ 1145 \t-D Enable the debug socket option\n\ 1146 \t-d Detach from stdin\n"); 1147 #ifdef IPSEC 1148 fprintf(stderr, "\ 1149 \t-E Use IPsec ESP\n\ 1150 \t-e policy Use specified IPsec policy\n"); 1151 #endif 1152 fprintf(stderr, "\ 1153 \t-F Pass socket fd\n\ 1154 \t-h This help text\n\ 1155 \t-I length TCP receive buffer length\n\ 1156 \t-i secs\t Delay interval for lines sent, ports scanned\n\ 1157 \t-k Keep inbound sockets open for multiple connects\n\ 1158 \t-l Listen mode, for inbound connects\n\ 1159 \t-N Shutdown the network socket after EOF on stdin\n\ 1160 \t-n Suppress name/port resolutions\n\ 1161 \t--no-tcpopt Disable TCP options\n\ 1162 \t-O length TCP send buffer length\n\ 1163 \t-P proxyuser\tUsername for proxy authentication\n\ 1164 \t-p port\t Specify local port for remote connects\n\ 1165 \t-r Randomize remote ports\n\ 1166 \t-S Enable the TCP MD5 signature option\n\ 1167 \t-s addr\t Local source address\n\ 1168 \t-T toskeyword\tSet IP Type of Service\n\ 1169 \t-t Answer TELNET negotiation\n\ 1170 \t-U Use UNIX domain socket\n\ 1171 \t-u UDP mode\n\ 1172 \t-V rtable Specify alternate routing table\n\ 1173 \t-v Verbose\n\ 1174 \t-w secs\t Timeout for connects and final net reads\n\ 1175 \t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\ 1176 \t-x addr[:port]\tSpecify proxy address and port\n\ 1177 \t-z Zero-I/O mode [used for scanning]\n\ 1178 Port numbers can be individual or ranges: lo-hi [inclusive]\n"); 1179 #ifdef IPSEC 1180 fprintf(stderr, "See ipsec_set_policy(3) for -e argument format\n"); 1181 #endif 1182 exit(1); 1183 } 1184 1185 #ifdef IPSEC 1186 void 1187 add_ipsec_policy(int s, char *policy) 1188 { 1189 char *raw; 1190 int e; 1191 1192 raw = ipsec_set_policy(policy, strlen(policy)); 1193 if (raw == NULL) 1194 errx(1, "ipsec_set_policy `%s': %s", policy, 1195 ipsec_strerror()); 1196 e = setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, raw, 1197 ipsec_get_policylen(raw)); 1198 if (e < 0) 1199 err(1, "ipsec policy cannot be configured"); 1200 free(raw); 1201 if (vflag) 1202 fprintf(stderr, "ipsec policy configured: `%s'\n", policy); 1203 return; 1204 } 1205 #endif /* IPSEC */ 1206 1207 void 1208 usage(int ret) 1209 { 1210 fprintf(stderr, 1211 #ifdef IPSEC 1212 "usage: nc [-46DdEFhklNnrStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n" 1213 #else 1214 "usage: nc [-46DdFhklNnrStUuvz] [-I length] [-i interval] [-O length]\n" 1215 #endif 1216 "\t [-P proxy_username] [-p source_port] [-s source] [-T ToS]\n" 1217 "\t [-V rtable] [-w timeout] [-X proxy_protocol]\n" 1218 "\t [-x proxy_address[:port]] [destination] [port]\n"); 1219 if (ret) 1220 exit(1); 1221 } 1222