1 /* $OpenBSD: netcat.c,v 1.130 2015/07/26 19:12:28 chl 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 #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 <fcntl.h> 56 #include <limits.h> 57 #include <netdb.h> 58 #include <poll.h> 59 #include <signal.h> 60 #include <stdarg.h> 61 #include <stdio.h> 62 #include <stdlib.h> 63 #include <string.h> 64 #include <unistd.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 #define POLL_STDIN 0 77 #define POLL_NETOUT 1 78 #define POLL_NETIN 2 79 #define POLL_STDOUT 3 80 #define BUFSIZE 16384 81 82 /* Command Line Options */ 83 int dflag; /* detached, no stdin */ 84 int Fflag; /* fdpass sock to stdout */ 85 unsigned int iflag; /* Interval Flag */ 86 int kflag; /* More than one connect */ 87 int lflag; /* Bind to local port */ 88 int Nflag; /* shutdown() network socket */ 89 int nflag; /* Don't do name look up */ 90 int FreeBSD_Oflag; /* Do not use TCP options */ 91 char *Pflag; /* Proxy username */ 92 char *pflag; /* Localport flag */ 93 int rflag; /* Random ports flag */ 94 char *sflag; /* Source Address */ 95 int tflag; /* Telnet Emulation */ 96 int uflag; /* UDP - Default to TCP */ 97 int vflag; /* Verbosity */ 98 int xflag; /* Socks proxy */ 99 int zflag; /* Port Scan Flag */ 100 int Dflag; /* sodebug */ 101 int Iflag; /* TCP receive buffer size */ 102 int Oflag; /* TCP send buffer size */ 103 int Sflag; /* TCP MD5 signature option */ 104 int Tflag = -1; /* IP Type of Service */ 105 int rtableid = -1; 106 107 int timeout = -1; 108 int family = AF_UNSPEC; 109 char *portlist[PORT_MAX+1]; 110 char *unix_dg_tmp_socket; 111 112 void atelnet(int, unsigned char *, unsigned int); 113 void build_ports(char *); 114 void help(void); 115 int local_listen(char *, char *, struct addrinfo); 116 void readwrite(int); 117 void fdpass(int nfd) __attribute__((noreturn)); 118 int remote_connect(const char *, const char *, struct addrinfo); 119 int timeout_connect(int, const struct sockaddr *, socklen_t); 120 int socks_connect(const char *, const char *, struct addrinfo, 121 const char *, const char *, struct addrinfo, int, const char *); 122 int udptest(int); 123 int unix_bind(char *); 124 int unix_connect(char *); 125 int unix_listen(char *); 126 void set_common_sockopts(int, int); 127 int map_tos(char *, int *); 128 void report_connect(const struct sockaddr *, socklen_t); 129 void usage(int); 130 ssize_t drainbuf(int, unsigned char *, size_t *); 131 ssize_t fillbuf(int, unsigned char *, size_t *); 132 133 #ifdef IPSEC 134 void add_ipsec_policy(int, char *); 135 136 char *ipsec_policy[2]; 137 #endif 138 139 int 140 main(int argc, char *argv[]) 141 { 142 int ch, s, ret, socksv, ipsec_count; 143 int numfibs; 144 size_t intsize = sizeof(int); 145 char *host, *uport; 146 struct addrinfo hints; 147 struct servent *sv; 148 socklen_t len; 149 struct sockaddr_storage cliaddr; 150 char *proxy; 151 const char *errstr, *proxyhost = "", *proxyport = NULL; 152 struct addrinfo proxyhints; 153 char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE]; 154 struct option longopts[] = { 155 { "no-tcpopt", no_argument, &FreeBSD_Oflag, 1 }, 156 { NULL, 0, NULL, 0 } 157 }; 158 159 ret = 1; 160 ipsec_count = 0; 161 s = 0; 162 socksv = 5; 163 host = NULL; 164 uport = NULL; 165 sv = NULL; 166 167 signal(SIGPIPE, SIG_IGN); 168 169 while ((ch = getopt_long(argc, argv, 170 "46DdEe:FhI:i:klNnoO:P:p:rSs:tT:UuV:vw:X:x:z", 171 longopts, NULL)) != -1) { 172 switch (ch) { 173 case '4': 174 family = AF_INET; 175 break; 176 case '6': 177 family = AF_INET6; 178 break; 179 case 'U': 180 family = AF_UNIX; 181 break; 182 case 'X': 183 if (strcasecmp(optarg, "connect") == 0) 184 socksv = -1; /* HTTP proxy CONNECT */ 185 else if (strcmp(optarg, "4") == 0) 186 socksv = 4; /* SOCKS v.4 */ 187 else if (strcmp(optarg, "5") == 0) 188 socksv = 5; /* SOCKS v.5 */ 189 else 190 errx(1, "unsupported proxy protocol"); 191 break; 192 case 'd': 193 dflag = 1; 194 break; 195 case 'e': 196 #ifdef IPSEC 197 ipsec_policy[ipsec_count++ % 2] = optarg; 198 #else 199 errx(1, "IPsec support unavailable."); 200 #endif 201 break; 202 case 'E': 203 #ifdef IPSEC 204 ipsec_policy[0] = "in ipsec esp/transport//require"; 205 ipsec_policy[1] = "out ipsec esp/transport//require"; 206 #else 207 errx(1, "IPsec support unavailable."); 208 #endif 209 break; 210 case 'F': 211 Fflag = 1; 212 break; 213 case 'h': 214 help(); 215 break; 216 case 'i': 217 iflag = strtonum(optarg, 0, UINT_MAX, &errstr); 218 if (errstr) 219 errx(1, "interval %s: %s", errstr, optarg); 220 break; 221 case 'k': 222 kflag = 1; 223 break; 224 case 'l': 225 lflag = 1; 226 break; 227 case 'N': 228 Nflag = 1; 229 break; 230 case 'n': 231 nflag = 1; 232 break; 233 case 'o': 234 fprintf(stderr, "option -o is deprecated.\n"); 235 break; 236 case 'P': 237 Pflag = optarg; 238 break; 239 case 'p': 240 pflag = optarg; 241 break; 242 case 'r': 243 rflag = 1; 244 break; 245 case 's': 246 sflag = optarg; 247 break; 248 case 't': 249 tflag = 1; 250 break; 251 case 'u': 252 uflag = 1; 253 break; 254 case 'V': 255 if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1) 256 errx(1, "Multiple FIBS not supported"); 257 rtableid = (int)strtonum(optarg, 0, 258 numfibs - 1, &errstr); 259 if (errstr) 260 errx(1, "rtable %s: %s", errstr, optarg); 261 break; 262 case 'v': 263 vflag = 1; 264 break; 265 case 'w': 266 timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr); 267 if (errstr) 268 errx(1, "timeout %s: %s", errstr, optarg); 269 timeout *= 1000; 270 break; 271 case 'x': 272 xflag = 1; 273 if ((proxy = strdup(optarg)) == NULL) 274 err(1, NULL); 275 break; 276 case 'z': 277 zflag = 1; 278 break; 279 case 'D': 280 Dflag = 1; 281 break; 282 case 'I': 283 Iflag = strtonum(optarg, 1, 65536 << 14, &errstr); 284 if (errstr != NULL) 285 errx(1, "TCP receive window %s: %s", 286 errstr, optarg); 287 break; 288 case 'O': 289 Oflag = strtonum(optarg, 1, 65536 << 14, &errstr); 290 if (errstr != NULL) { 291 if (strcmp(errstr, "invalid") != 0) 292 errx(1, "TCP send window %s: %s", 293 errstr, optarg); 294 } 295 break; 296 case 'S': 297 Sflag = 1; 298 break; 299 case 'T': 300 errstr = NULL; 301 errno = 0; 302 if (map_tos(optarg, &Tflag)) 303 break; 304 if (strlen(optarg) > 1 && optarg[0] == '0' && 305 optarg[1] == 'x') 306 Tflag = (int)strtol(optarg, NULL, 16); 307 else 308 Tflag = (int)strtonum(optarg, 0, 255, 309 &errstr); 310 if (Tflag < 0 || Tflag > 255 || errstr || errno) 311 errx(1, "illegal tos value %s", optarg); 312 break; 313 default: 314 usage(1); 315 } 316 } 317 argc -= optind; 318 argv += optind; 319 320 /* Cruft to make sure options are clean, and used properly. */ 321 if (argv[0] && !argv[1] && family == AF_UNIX) { 322 host = argv[0]; 323 uport = NULL; 324 } else if (argv[0] && !argv[1]) { 325 if (!lflag) 326 usage(1); 327 uport = argv[0]; 328 host = NULL; 329 } else if (argv[0] && argv[1]) { 330 host = argv[0]; 331 uport = argv[1]; 332 } else 333 usage(1); 334 335 if (lflag && sflag) 336 errx(1, "cannot use -s and -l"); 337 if (lflag && pflag) 338 errx(1, "cannot use -p and -l"); 339 if (lflag && zflag) 340 errx(1, "cannot use -z and -l"); 341 if (!lflag && kflag) 342 errx(1, "must use -l with -k"); 343 344 /* Get name of temporary socket for unix datagram client */ 345 if ((family == AF_UNIX) && uflag && !lflag) { 346 if (sflag) { 347 unix_dg_tmp_socket = sflag; 348 } else { 349 strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX", 350 UNIX_DG_TMP_SOCKET_SIZE); 351 if (mktemp(unix_dg_tmp_socket_buf) == NULL) 352 err(1, "mktemp"); 353 unix_dg_tmp_socket = unix_dg_tmp_socket_buf; 354 } 355 } 356 357 /* Initialize addrinfo structure. */ 358 if (family != AF_UNIX) { 359 memset(&hints, 0, sizeof(struct addrinfo)); 360 hints.ai_family = family; 361 hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 362 hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 363 if (nflag) 364 hints.ai_flags |= AI_NUMERICHOST; 365 } 366 367 if (xflag) { 368 if (uflag) 369 errx(1, "no proxy support for UDP mode"); 370 371 if (lflag) 372 errx(1, "no proxy support for listen"); 373 374 if (family == AF_UNIX) 375 errx(1, "no proxy support for unix sockets"); 376 377 /* XXX IPv6 transport to proxy would probably work */ 378 if (family == AF_INET6) 379 errx(1, "no proxy support for IPv6"); 380 381 if (sflag) 382 errx(1, "no proxy support for local source address"); 383 384 proxyhost = strsep(&proxy, ":"); 385 proxyport = proxy; 386 387 memset(&proxyhints, 0, sizeof(struct addrinfo)); 388 proxyhints.ai_family = family; 389 proxyhints.ai_socktype = SOCK_STREAM; 390 proxyhints.ai_protocol = IPPROTO_TCP; 391 if (nflag) 392 proxyhints.ai_flags |= AI_NUMERICHOST; 393 } 394 395 if (lflag) { 396 int connfd; 397 ret = 0; 398 399 if (family == AF_UNIX) { 400 if (uflag) 401 s = unix_bind(host); 402 else 403 s = unix_listen(host); 404 } 405 406 /* Allow only one connection at a time, but stay alive. */ 407 for (;;) { 408 if (family != AF_UNIX) 409 s = local_listen(host, uport, hints); 410 if (s < 0) 411 err(1, NULL); 412 /* 413 * For UDP and -k, don't connect the socket, let it 414 * receive datagrams from multiple socket pairs. 415 */ 416 if (uflag && kflag) 417 readwrite(s); 418 /* 419 * For UDP and not -k, we will use recvfrom() initially 420 * to wait for a caller, then use the regular functions 421 * to talk to the caller. 422 */ 423 else if (uflag && !kflag) { 424 int rv, plen; 425 char buf[16384]; 426 struct sockaddr_storage z; 427 428 len = sizeof(z); 429 plen = 2048; 430 rv = recvfrom(s, buf, plen, MSG_PEEK, 431 (struct sockaddr *)&z, &len); 432 if (rv < 0) 433 err(1, "recvfrom"); 434 435 rv = connect(s, (struct sockaddr *)&z, len); 436 if (rv < 0) 437 err(1, "connect"); 438 439 if (vflag) 440 report_connect((struct sockaddr *)&z, len); 441 442 readwrite(s); 443 } else { 444 len = sizeof(cliaddr); 445 connfd = accept(s, (struct sockaddr *)&cliaddr, 446 &len); 447 if (connfd == -1) { 448 /* For now, all errnos are fatal */ 449 err(1, "accept"); 450 } 451 if (vflag) 452 report_connect((struct sockaddr *)&cliaddr, len); 453 454 readwrite(connfd); 455 close(connfd); 456 } 457 458 if (family != AF_UNIX) 459 close(s); 460 else if (uflag) { 461 if (connect(s, NULL, 0) < 0) 462 err(1, "connect"); 463 } 464 465 if (!kflag) 466 break; 467 } 468 } else if (family == AF_UNIX) { 469 ret = 0; 470 471 if ((s = unix_connect(host)) > 0 && !zflag) { 472 readwrite(s); 473 close(s); 474 } else 475 ret = 1; 476 477 if (uflag) 478 unlink(unix_dg_tmp_socket); 479 exit(ret); 480 481 } else { 482 int i = 0; 483 484 /* Construct the portlist[] array. */ 485 build_ports(uport); 486 487 /* Cycle through portlist, connecting to each port. */ 488 for (i = 0; portlist[i] != NULL; i++) { 489 if (s) 490 close(s); 491 492 if (xflag) 493 s = socks_connect(host, portlist[i], hints, 494 proxyhost, proxyport, proxyhints, socksv, 495 Pflag); 496 else 497 s = remote_connect(host, portlist[i], hints); 498 499 if (s < 0) 500 continue; 501 502 ret = 0; 503 if (vflag || zflag) { 504 /* For UDP, make sure we are connected. */ 505 if (uflag) { 506 if (udptest(s) == -1) { 507 ret = 1; 508 continue; 509 } 510 } 511 512 /* Don't look up port if -n. */ 513 if (nflag) 514 sv = NULL; 515 else { 516 sv = getservbyport( 517 ntohs(atoi(portlist[i])), 518 uflag ? "udp" : "tcp"); 519 } 520 521 fprintf(stderr, 522 "Connection to %s %s port [%s/%s] " 523 "succeeded!\n", host, portlist[i], 524 uflag ? "udp" : "tcp", 525 sv ? sv->s_name : "*"); 526 } 527 if (Fflag) 528 fdpass(s); 529 else if (!zflag) 530 readwrite(s); 531 } 532 } 533 534 if (s) 535 close(s); 536 537 exit(ret); 538 } 539 540 /* 541 * unix_bind() 542 * Returns a unix socket bound to the given path 543 */ 544 int 545 unix_bind(char *path) 546 { 547 struct sockaddr_un sun; 548 int s; 549 550 /* Create unix domain socket. */ 551 if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM, 552 0)) < 0) 553 return (-1); 554 555 memset(&sun, 0, sizeof(struct sockaddr_un)); 556 sun.sun_family = AF_UNIX; 557 558 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 559 sizeof(sun.sun_path)) { 560 close(s); 561 errno = ENAMETOOLONG; 562 return (-1); 563 } 564 565 if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 566 close(s); 567 return (-1); 568 } 569 return (s); 570 } 571 572 /* 573 * unix_connect() 574 * Returns a socket connected to a local unix socket. Returns -1 on failure. 575 */ 576 int 577 unix_connect(char *path) 578 { 579 struct sockaddr_un sun; 580 int s; 581 582 if (uflag) { 583 if ((s = unix_bind(unix_dg_tmp_socket)) < 0) 584 return (-1); 585 } else { 586 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 587 return (-1); 588 } 589 (void)fcntl(s, F_SETFD, FD_CLOEXEC); 590 591 memset(&sun, 0, sizeof(struct sockaddr_un)); 592 sun.sun_family = AF_UNIX; 593 594 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 595 sizeof(sun.sun_path)) { 596 close(s); 597 errno = ENAMETOOLONG; 598 return (-1); 599 } 600 if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 601 close(s); 602 return (-1); 603 } 604 return (s); 605 606 } 607 608 /* 609 * unix_listen() 610 * Create a unix domain socket, and listen on it. 611 */ 612 int 613 unix_listen(char *path) 614 { 615 int s; 616 if ((s = unix_bind(path)) < 0) 617 return (-1); 618 619 if (listen(s, 5) < 0) { 620 close(s); 621 return (-1); 622 } 623 return (s); 624 } 625 626 /* 627 * remote_connect() 628 * Returns a socket connected to a remote host. Properly binds to a local 629 * port or source address if needed. Returns -1 on failure. 630 */ 631 int 632 remote_connect(const char *host, const char *port, struct addrinfo hints) 633 { 634 struct addrinfo *res, *res0; 635 int s, error, on = 1; 636 637 if ((error = getaddrinfo(host, port, &hints, &res))) 638 errx(1, "getaddrinfo: %s", gai_strerror(error)); 639 640 res0 = res; 641 do { 642 if ((s = socket(res0->ai_family, res0->ai_socktype, 643 res0->ai_protocol)) < 0) 644 continue; 645 #ifdef IPSEC 646 if (ipsec_policy[0] != NULL) 647 add_ipsec_policy(s, ipsec_policy[0]); 648 if (ipsec_policy[1] != NULL) 649 add_ipsec_policy(s, ipsec_policy[1]); 650 #endif 651 652 if (rtableid >= 0 && (setsockopt(s, SOL_SOCKET, SO_SETFIB, 653 &rtableid, sizeof(rtableid)) == -1)) 654 err(1, "setsockopt SO_SETFIB"); 655 656 /* Bind to a local port or source address if specified. */ 657 if (sflag || pflag) { 658 struct addrinfo ahints, *ares; 659 660 /* try IP_BINDANY, but don't insist */ 661 setsockopt(s, IPPROTO_IP, IP_BINDANY, &on, sizeof(on)); 662 memset(&ahints, 0, sizeof(struct addrinfo)); 663 ahints.ai_family = res0->ai_family; 664 ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 665 ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 666 ahints.ai_flags = AI_PASSIVE; 667 if ((error = getaddrinfo(sflag, pflag, &ahints, &ares))) 668 errx(1, "getaddrinfo: %s", gai_strerror(error)); 669 670 if (bind(s, (struct sockaddr *)ares->ai_addr, 671 ares->ai_addrlen) < 0) 672 err(1, "bind failed"); 673 freeaddrinfo(ares); 674 } 675 676 set_common_sockopts(s, res0->ai_family); 677 678 if (timeout_connect(s, res0->ai_addr, res0->ai_addrlen) == 0) 679 break; 680 else if (vflag) 681 warn("connect to %s port %s (%s) failed", host, port, 682 uflag ? "udp" : "tcp"); 683 684 close(s); 685 s = -1; 686 } while ((res0 = res0->ai_next) != NULL); 687 688 freeaddrinfo(res); 689 690 return (s); 691 } 692 693 int 694 timeout_connect(int s, const struct sockaddr *name, socklen_t namelen) 695 { 696 struct pollfd pfd; 697 socklen_t optlen; 698 int flags, optval; 699 int ret; 700 701 if (timeout != -1) { 702 flags = fcntl(s, F_GETFL, 0); 703 if (fcntl(s, F_SETFL, flags | O_NONBLOCK) == -1) 704 err(1, "set non-blocking mode"); 705 } 706 707 if ((ret = connect(s, name, namelen)) != 0 && errno == EINPROGRESS) { 708 pfd.fd = s; 709 pfd.events = POLLOUT; 710 if ((ret = poll(&pfd, 1, timeout)) == 1) { 711 optlen = sizeof(optval); 712 if ((ret = getsockopt(s, SOL_SOCKET, SO_ERROR, 713 &optval, &optlen)) == 0) { 714 errno = optval; 715 ret = optval == 0 ? 0 : -1; 716 } 717 } else if (ret == 0) { 718 errno = ETIMEDOUT; 719 ret = -1; 720 } else 721 err(1, "poll failed"); 722 } 723 724 if (timeout != -1 && fcntl(s, F_SETFL, flags) == -1) 725 err(1, "restoring flags"); 726 727 return (ret); 728 } 729 730 /* 731 * local_listen() 732 * Returns a socket listening on a local port, binds to specified source 733 * address. Returns -1 on failure. 734 */ 735 int 736 local_listen(char *host, char *port, struct addrinfo hints) 737 { 738 struct addrinfo *res, *res0; 739 int s, ret, x = 1; 740 int error; 741 742 /* Allow nodename to be null. */ 743 hints.ai_flags |= AI_PASSIVE; 744 745 /* 746 * In the case of binding to a wildcard address 747 * default to binding to an ipv4 address. 748 */ 749 if (host == NULL && hints.ai_family == AF_UNSPEC) 750 hints.ai_family = AF_INET; 751 752 if ((error = getaddrinfo(host, port, &hints, &res))) 753 errx(1, "getaddrinfo: %s", gai_strerror(error)); 754 755 res0 = res; 756 do { 757 if ((s = socket(res0->ai_family, res0->ai_socktype, 758 res0->ai_protocol)) < 0) 759 continue; 760 761 if (rtableid >= 0 && (setsockopt(s, SOL_SOCKET, SO_SETFIB, 762 &rtableid, sizeof(rtableid)) == -1)) 763 err(1, "setsockopt SO_SETFIB"); 764 765 ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x)); 766 if (ret == -1) 767 err(1, NULL); 768 #ifdef IPSEC 769 if (ipsec_policy[0] != NULL) 770 add_ipsec_policy(s, ipsec_policy[0]); 771 if (ipsec_policy[1] != NULL) 772 add_ipsec_policy(s, ipsec_policy[1]); 773 #endif 774 if (FreeBSD_Oflag) { 775 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 776 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 777 err(1, "disable TCP options"); 778 } 779 780 set_common_sockopts(s, res0->ai_family); 781 782 if (bind(s, (struct sockaddr *)res0->ai_addr, 783 res0->ai_addrlen) == 0) 784 break; 785 786 close(s); 787 s = -1; 788 } while ((res0 = res0->ai_next) != NULL); 789 790 if (!uflag && s != -1) { 791 if (listen(s, 1) < 0) 792 err(1, "listen"); 793 } 794 795 freeaddrinfo(res); 796 797 return (s); 798 } 799 800 /* 801 * readwrite() 802 * Loop that polls on the network file descriptor and stdin. 803 */ 804 void 805 readwrite(int net_fd) 806 { 807 struct pollfd pfd[4]; 808 int stdin_fd = STDIN_FILENO; 809 int stdout_fd = STDOUT_FILENO; 810 unsigned char netinbuf[BUFSIZE]; 811 size_t netinbufpos = 0; 812 unsigned char stdinbuf[BUFSIZE]; 813 size_t stdinbufpos = 0; 814 int n, num_fds; 815 ssize_t ret; 816 817 /* don't read from stdin if requested */ 818 if (dflag) 819 stdin_fd = -1; 820 821 /* stdin */ 822 pfd[POLL_STDIN].fd = stdin_fd; 823 pfd[POLL_STDIN].events = POLLIN; 824 825 /* network out */ 826 pfd[POLL_NETOUT].fd = net_fd; 827 pfd[POLL_NETOUT].events = 0; 828 829 /* network in */ 830 pfd[POLL_NETIN].fd = net_fd; 831 pfd[POLL_NETIN].events = POLLIN; 832 833 /* stdout */ 834 pfd[POLL_STDOUT].fd = stdout_fd; 835 pfd[POLL_STDOUT].events = 0; 836 837 while (1) { 838 /* both inputs are gone, buffers are empty, we are done */ 839 if (pfd[POLL_STDIN].fd == -1 && pfd[POLL_NETIN].fd == -1 840 && stdinbufpos == 0 && netinbufpos == 0) { 841 close(net_fd); 842 return; 843 } 844 /* both outputs are gone, we can't continue */ 845 if (pfd[POLL_NETOUT].fd == -1 && pfd[POLL_STDOUT].fd == -1) { 846 close(net_fd); 847 return; 848 } 849 /* listen and net in gone, queues empty, done */ 850 if (lflag && pfd[POLL_NETIN].fd == -1 851 && stdinbufpos == 0 && netinbufpos == 0) { 852 close(net_fd); 853 return; 854 } 855 856 /* help says -i is for "wait between lines sent". We read and 857 * write arbitrary amounts of data, and we don't want to start 858 * scanning for newlines, so this is as good as it gets */ 859 if (iflag) 860 sleep(iflag); 861 862 /* poll */ 863 num_fds = poll(pfd, 4, timeout); 864 865 /* treat poll errors */ 866 if (num_fds == -1) { 867 close(net_fd); 868 err(1, "polling error"); 869 } 870 871 /* timeout happened */ 872 if (num_fds == 0) 873 return; 874 875 /* treat socket error conditions */ 876 for (n = 0; n < 4; n++) { 877 if (pfd[n].revents & (POLLERR|POLLNVAL)) { 878 pfd[n].fd = -1; 879 } 880 } 881 /* reading is possible after HUP */ 882 if (pfd[POLL_STDIN].events & POLLIN && 883 pfd[POLL_STDIN].revents & POLLHUP && 884 ! (pfd[POLL_STDIN].revents & POLLIN)) 885 pfd[POLL_STDIN].fd = -1; 886 887 if (pfd[POLL_NETIN].events & POLLIN && 888 pfd[POLL_NETIN].revents & POLLHUP && 889 ! (pfd[POLL_NETIN].revents & POLLIN)) 890 pfd[POLL_NETIN].fd = -1; 891 892 if (pfd[POLL_NETOUT].revents & POLLHUP) { 893 if (Nflag) 894 shutdown(pfd[POLL_NETOUT].fd, SHUT_WR); 895 pfd[POLL_NETOUT].fd = -1; 896 } 897 /* if HUP, stop watching stdout */ 898 if (pfd[POLL_STDOUT].revents & POLLHUP) 899 pfd[POLL_STDOUT].fd = -1; 900 /* if no net out, stop watching stdin */ 901 if (pfd[POLL_NETOUT].fd == -1) 902 pfd[POLL_STDIN].fd = -1; 903 /* if no stdout, stop watching net in */ 904 if (pfd[POLL_STDOUT].fd == -1) { 905 if (pfd[POLL_NETIN].fd != -1) 906 shutdown(pfd[POLL_NETIN].fd, SHUT_RD); 907 pfd[POLL_NETIN].fd = -1; 908 } 909 910 /* try to read from stdin */ 911 if (pfd[POLL_STDIN].revents & POLLIN && stdinbufpos < BUFSIZE) { 912 ret = fillbuf(pfd[POLL_STDIN].fd, stdinbuf, 913 &stdinbufpos); 914 /* error or eof on stdin - remove from pfd */ 915 if (ret == 0 || ret == -1) 916 pfd[POLL_STDIN].fd = -1; 917 /* read something - poll net out */ 918 if (stdinbufpos > 0) 919 pfd[POLL_NETOUT].events = POLLOUT; 920 /* filled buffer - remove self from polling */ 921 if (stdinbufpos == BUFSIZE) 922 pfd[POLL_STDIN].events = 0; 923 } 924 /* try to write to network */ 925 if (pfd[POLL_NETOUT].revents & POLLOUT && stdinbufpos > 0) { 926 ret = drainbuf(pfd[POLL_NETOUT].fd, stdinbuf, 927 &stdinbufpos); 928 if (ret == -1) 929 pfd[POLL_NETOUT].fd = -1; 930 /* buffer empty - remove self from polling */ 931 if (stdinbufpos == 0) 932 pfd[POLL_NETOUT].events = 0; 933 /* buffer no longer full - poll stdin again */ 934 if (stdinbufpos < BUFSIZE) 935 pfd[POLL_STDIN].events = POLLIN; 936 } 937 /* try to read from network */ 938 if (pfd[POLL_NETIN].revents & POLLIN && netinbufpos < BUFSIZE) { 939 ret = fillbuf(pfd[POLL_NETIN].fd, netinbuf, 940 &netinbufpos); 941 if (ret == -1) 942 pfd[POLL_NETIN].fd = -1; 943 /* eof on net in - remove from pfd */ 944 if (ret == 0) { 945 shutdown(pfd[POLL_NETIN].fd, SHUT_RD); 946 pfd[POLL_NETIN].fd = -1; 947 } 948 /* read something - poll stdout */ 949 if (netinbufpos > 0) 950 pfd[POLL_STDOUT].events = POLLOUT; 951 /* filled buffer - remove self from polling */ 952 if (netinbufpos == BUFSIZE) 953 pfd[POLL_NETIN].events = 0; 954 /* handle telnet */ 955 if (tflag) 956 atelnet(pfd[POLL_NETIN].fd, netinbuf, 957 netinbufpos); 958 } 959 /* try to write to stdout */ 960 if (pfd[POLL_STDOUT].revents & POLLOUT && netinbufpos > 0) { 961 ret = drainbuf(pfd[POLL_STDOUT].fd, netinbuf, 962 &netinbufpos); 963 if (ret == -1) 964 pfd[POLL_STDOUT].fd = -1; 965 /* buffer empty - remove self from polling */ 966 if (netinbufpos == 0) 967 pfd[POLL_STDOUT].events = 0; 968 /* buffer no longer full - poll net in again */ 969 if (netinbufpos < BUFSIZE) 970 pfd[POLL_NETIN].events = POLLIN; 971 } 972 973 /* stdin gone and queue empty? */ 974 if (pfd[POLL_STDIN].fd == -1 && stdinbufpos == 0) { 975 if (pfd[POLL_NETOUT].fd != -1 && Nflag) 976 shutdown(pfd[POLL_NETOUT].fd, SHUT_WR); 977 pfd[POLL_NETOUT].fd = -1; 978 } 979 /* net in gone and queue empty? */ 980 if (pfd[POLL_NETIN].fd == -1 && netinbufpos == 0) { 981 pfd[POLL_STDOUT].fd = -1; 982 } 983 } 984 } 985 986 ssize_t 987 drainbuf(int fd, unsigned char *buf, size_t *bufpos) 988 { 989 ssize_t n; 990 ssize_t adjust; 991 992 n = write(fd, buf, *bufpos); 993 /* don't treat EAGAIN, EINTR as error */ 994 if (n == -1 && (errno == EAGAIN || errno == EINTR)) 995 n = -2; 996 if (n <= 0) 997 return n; 998 /* adjust buffer */ 999 adjust = *bufpos - n; 1000 if (adjust > 0) 1001 memmove(buf, buf + n, adjust); 1002 *bufpos -= n; 1003 return n; 1004 } 1005 1006 1007 ssize_t 1008 fillbuf(int fd, unsigned char *buf, size_t *bufpos) 1009 { 1010 size_t num = BUFSIZE - *bufpos; 1011 ssize_t n; 1012 1013 n = read(fd, buf + *bufpos, num); 1014 /* don't treat EAGAIN, EINTR as error */ 1015 if (n == -1 && (errno == EAGAIN || errno == EINTR)) 1016 n = -2; 1017 if (n <= 0) 1018 return n; 1019 *bufpos += n; 1020 return n; 1021 } 1022 1023 /* 1024 * fdpass() 1025 * Pass the connected file descriptor to stdout and exit. 1026 */ 1027 void 1028 fdpass(int nfd) 1029 { 1030 struct msghdr mh; 1031 union { 1032 struct cmsghdr hdr; 1033 char buf[CMSG_SPACE(sizeof(int))]; 1034 } cmsgbuf; 1035 struct cmsghdr *cmsg; 1036 struct iovec iov; 1037 char c = '\0'; 1038 ssize_t r; 1039 struct pollfd pfd; 1040 1041 /* Avoid obvious stupidity */ 1042 if (isatty(STDOUT_FILENO)) 1043 errx(1, "Cannot pass file descriptor to tty"); 1044 1045 bzero(&mh, sizeof(mh)); 1046 bzero(&cmsgbuf, sizeof(cmsgbuf)); 1047 bzero(&iov, sizeof(iov)); 1048 1049 mh.msg_control = (caddr_t)&cmsgbuf.buf; 1050 mh.msg_controllen = sizeof(cmsgbuf.buf); 1051 cmsg = CMSG_FIRSTHDR(&mh); 1052 cmsg->cmsg_len = CMSG_LEN(sizeof(int)); 1053 cmsg->cmsg_level = SOL_SOCKET; 1054 cmsg->cmsg_type = SCM_RIGHTS; 1055 *(int *)CMSG_DATA(cmsg) = nfd; 1056 1057 iov.iov_base = &c; 1058 iov.iov_len = 1; 1059 mh.msg_iov = &iov; 1060 mh.msg_iovlen = 1; 1061 1062 bzero(&pfd, sizeof(pfd)); 1063 pfd.fd = STDOUT_FILENO; 1064 pfd.events = POLLOUT; 1065 for (;;) { 1066 r = sendmsg(STDOUT_FILENO, &mh, 0); 1067 if (r == -1) { 1068 if (errno == EAGAIN || errno == EINTR) { 1069 if (poll(&pfd, 1, -1) == -1) 1070 err(1, "poll"); 1071 continue; 1072 } 1073 err(1, "sendmsg"); 1074 } else if (r != 1) 1075 errx(1, "sendmsg: unexpected return value %zd", r); 1076 else 1077 break; 1078 } 1079 exit(0); 1080 } 1081 1082 /* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */ 1083 void 1084 atelnet(int nfd, unsigned char *buf, unsigned int size) 1085 { 1086 unsigned char *p, *end; 1087 unsigned char obuf[4]; 1088 1089 if (size < 3) 1090 return; 1091 end = buf + size - 2; 1092 1093 for (p = buf; p < end; p++) { 1094 if (*p != IAC) 1095 continue; 1096 1097 obuf[0] = IAC; 1098 p++; 1099 if ((*p == WILL) || (*p == WONT)) 1100 obuf[1] = DONT; 1101 else if ((*p == DO) || (*p == DONT)) 1102 obuf[1] = WONT; 1103 else 1104 continue; 1105 1106 p++; 1107 obuf[2] = *p; 1108 if (atomicio(vwrite, nfd, obuf, 3) != 3) 1109 warn("Write Error!"); 1110 } 1111 } 1112 1113 /* 1114 * build_ports() 1115 * Build an array of ports in portlist[], listing each port 1116 * that we should try to connect to. 1117 */ 1118 void 1119 build_ports(char *p) 1120 { 1121 const char *errstr; 1122 char *n; 1123 int hi, lo, cp; 1124 int x = 0; 1125 1126 if ((n = strchr(p, '-')) != NULL) { 1127 *n = '\0'; 1128 n++; 1129 1130 /* Make sure the ports are in order: lowest->highest. */ 1131 hi = strtonum(n, 1, PORT_MAX, &errstr); 1132 if (errstr) 1133 errx(1, "port number %s: %s", errstr, n); 1134 lo = strtonum(p, 1, PORT_MAX, &errstr); 1135 if (errstr) 1136 errx(1, "port number %s: %s", errstr, p); 1137 1138 if (lo > hi) { 1139 cp = hi; 1140 hi = lo; 1141 lo = cp; 1142 } 1143 1144 /* Load ports sequentially. */ 1145 for (cp = lo; cp <= hi; cp++) { 1146 portlist[x] = calloc(1, PORT_MAX_LEN); 1147 if (portlist[x] == NULL) 1148 err(1, NULL); 1149 snprintf(portlist[x], PORT_MAX_LEN, "%d", cp); 1150 x++; 1151 } 1152 1153 /* Randomly swap ports. */ 1154 if (rflag) { 1155 int y; 1156 char *c; 1157 1158 for (x = 0; x <= (hi - lo); x++) { 1159 y = (arc4random() & 0xFFFF) % (hi - lo); 1160 c = portlist[x]; 1161 portlist[x] = portlist[y]; 1162 portlist[y] = c; 1163 } 1164 } 1165 } else { 1166 hi = strtonum(p, 1, PORT_MAX, &errstr); 1167 if (errstr) 1168 errx(1, "port number %s: %s", errstr, p); 1169 portlist[0] = strdup(p); 1170 if (portlist[0] == NULL) 1171 err(1, NULL); 1172 } 1173 } 1174 1175 /* 1176 * udptest() 1177 * Do a few writes to see if the UDP port is there. 1178 * Fails once PF state table is full. 1179 */ 1180 int 1181 udptest(int s) 1182 { 1183 int i, ret; 1184 1185 for (i = 0; i <= 3; i++) { 1186 if (write(s, "X", 1) == 1) 1187 ret = 1; 1188 else 1189 ret = -1; 1190 } 1191 return (ret); 1192 } 1193 1194 void 1195 set_common_sockopts(int s, int af) 1196 { 1197 int x = 1; 1198 1199 if (Sflag) { 1200 if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG, 1201 &x, sizeof(x)) == -1) 1202 err(1, NULL); 1203 } 1204 if (Dflag) { 1205 if (setsockopt(s, SOL_SOCKET, SO_DEBUG, 1206 &x, sizeof(x)) == -1) 1207 err(1, NULL); 1208 } 1209 if (Tflag != -1) { 1210 int proto, option; 1211 1212 if (af == AF_INET6) { 1213 proto = IPPROTO_IPV6; 1214 option = IPV6_TCLASS; 1215 } else { 1216 proto = IPPROTO_IP; 1217 option = IP_TOS; 1218 } 1219 1220 if (setsockopt(s, proto, option, &Tflag, sizeof(Tflag)) == -1) 1221 err(1, "set IP ToS"); 1222 } 1223 if (Iflag) { 1224 if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, 1225 &Iflag, sizeof(Iflag)) == -1) 1226 err(1, "set TCP receive buffer size"); 1227 } 1228 if (Oflag) { 1229 if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, 1230 &Oflag, sizeof(Oflag)) == -1) 1231 err(1, "set TCP send buffer size"); 1232 } 1233 if (FreeBSD_Oflag) { 1234 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 1235 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 1236 err(1, "disable TCP options"); 1237 } 1238 } 1239 1240 int 1241 map_tos(char *s, int *val) 1242 { 1243 /* DiffServ Codepoints and other TOS mappings */ 1244 const struct toskeywords { 1245 const char *keyword; 1246 int val; 1247 } *t, toskeywords[] = { 1248 { "af11", IPTOS_DSCP_AF11 }, 1249 { "af12", IPTOS_DSCP_AF12 }, 1250 { "af13", IPTOS_DSCP_AF13 }, 1251 { "af21", IPTOS_DSCP_AF21 }, 1252 { "af22", IPTOS_DSCP_AF22 }, 1253 { "af23", IPTOS_DSCP_AF23 }, 1254 { "af31", IPTOS_DSCP_AF31 }, 1255 { "af32", IPTOS_DSCP_AF32 }, 1256 { "af33", IPTOS_DSCP_AF33 }, 1257 { "af41", IPTOS_DSCP_AF41 }, 1258 { "af42", IPTOS_DSCP_AF42 }, 1259 { "af43", IPTOS_DSCP_AF43 }, 1260 { "critical", IPTOS_PREC_CRITIC_ECP }, 1261 { "cs0", IPTOS_DSCP_CS0 }, 1262 { "cs1", IPTOS_DSCP_CS1 }, 1263 { "cs2", IPTOS_DSCP_CS2 }, 1264 { "cs3", IPTOS_DSCP_CS3 }, 1265 { "cs4", IPTOS_DSCP_CS4 }, 1266 { "cs5", IPTOS_DSCP_CS5 }, 1267 { "cs6", IPTOS_DSCP_CS6 }, 1268 { "cs7", IPTOS_DSCP_CS7 }, 1269 { "ef", IPTOS_DSCP_EF }, 1270 { "inetcontrol", IPTOS_PREC_INTERNETCONTROL }, 1271 { "lowdelay", IPTOS_LOWDELAY }, 1272 { "netcontrol", IPTOS_PREC_NETCONTROL }, 1273 { "reliability", IPTOS_RELIABILITY }, 1274 { "throughput", IPTOS_THROUGHPUT }, 1275 { NULL, -1 }, 1276 }; 1277 1278 for (t = toskeywords; t->keyword != NULL; t++) { 1279 if (strcmp(s, t->keyword) == 0) { 1280 *val = t->val; 1281 return (1); 1282 } 1283 } 1284 1285 return (0); 1286 } 1287 1288 void 1289 report_connect(const struct sockaddr *sa, socklen_t salen) 1290 { 1291 char remote_host[NI_MAXHOST]; 1292 char remote_port[NI_MAXSERV]; 1293 int herr; 1294 int flags = NI_NUMERICSERV; 1295 1296 if (nflag) 1297 flags |= NI_NUMERICHOST; 1298 1299 if ((herr = getnameinfo(sa, salen, 1300 remote_host, sizeof(remote_host), 1301 remote_port, sizeof(remote_port), 1302 flags)) != 0) { 1303 if (herr == EAI_SYSTEM) 1304 err(1, "getnameinfo"); 1305 else 1306 errx(1, "getnameinfo: %s", gai_strerror(herr)); 1307 } 1308 1309 fprintf(stderr, 1310 "Connection from %s %s " 1311 "received!\n", remote_host, remote_port); 1312 } 1313 1314 void 1315 help(void) 1316 { 1317 usage(0); 1318 fprintf(stderr, "\tCommand Summary:\n\ 1319 \t-4 Use IPv4\n\ 1320 \t-6 Use IPv6\n\ 1321 \t-D Enable the debug socket option\n\ 1322 \t-d Detach from stdin\n"); 1323 #ifdef IPSEC 1324 fprintf(stderr, "\ 1325 \t-E Use IPsec ESP\n\ 1326 \t-e policy Use specified IPsec policy\n"); 1327 #endif 1328 fprintf(stderr, "\ 1329 \t-F Pass socket fd\n\ 1330 \t-h This help text\n\ 1331 \t-I length TCP receive buffer length\n\ 1332 \t-i secs\t Delay interval for lines sent, ports scanned\n\ 1333 \t-k Keep inbound sockets open for multiple connects\n\ 1334 \t-l Listen mode, for inbound connects\n\ 1335 \t-N Shutdown the network socket after EOF on stdin\n\ 1336 \t-n Suppress name/port resolutions\n\ 1337 \t--no-tcpopt Disable TCP options\n\ 1338 \t-O length TCP send buffer length\n\ 1339 \t-P proxyuser\tUsername for proxy authentication\n\ 1340 \t-p port\t Specify local port for remote connects\n\ 1341 \t-r Randomize remote ports\n\ 1342 \t-S Enable the TCP MD5 signature option\n\ 1343 \t-s addr\t Local source address\n\ 1344 \t-T toskeyword\tSet IP Type of Service\n\ 1345 \t-t Answer TELNET negotiation\n\ 1346 \t-U Use UNIX domain socket\n\ 1347 \t-u UDP mode\n\ 1348 \t-V rtable Specify alternate routing table\n\ 1349 \t-v Verbose\n\ 1350 \t-w secs\t Timeout for connects and final net reads\n\ 1351 \t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\ 1352 \t-x addr[:port]\tSpecify proxy address and port\n\ 1353 \t-z Zero-I/O mode [used for scanning]\n\ 1354 Port numbers can be individual or ranges: lo-hi [inclusive]\n"); 1355 #ifdef IPSEC 1356 fprintf(stderr, "See ipsec_set_policy(3) for -e argument format\n"); 1357 #endif 1358 exit(1); 1359 } 1360 1361 #ifdef IPSEC 1362 void 1363 add_ipsec_policy(int s, char *policy) 1364 { 1365 char *raw; 1366 int e; 1367 1368 raw = ipsec_set_policy(policy, strlen(policy)); 1369 if (raw == NULL) 1370 errx(1, "ipsec_set_policy `%s': %s", policy, 1371 ipsec_strerror()); 1372 e = setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, raw, 1373 ipsec_get_policylen(raw)); 1374 if (e < 0) 1375 err(1, "ipsec policy cannot be configured"); 1376 free(raw); 1377 if (vflag) 1378 fprintf(stderr, "ipsec policy configured: `%s'\n", policy); 1379 return; 1380 } 1381 #endif /* IPSEC */ 1382 1383 void 1384 usage(int ret) 1385 { 1386 fprintf(stderr, 1387 #ifdef IPSEC 1388 "usage: nc [-46DdEFhklNnrStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n" 1389 #else 1390 "usage: nc [-46DdFhklNnrStUuvz] [-I length] [-i interval] [-O length]\n" 1391 #endif 1392 "\t [-P proxy_username] [-p source_port] [-s source] [-T ToS]\n" 1393 "\t [-V rtable] [-w timeout] [-X proxy_protocol]\n" 1394 "\t [-x proxy_address[:port]] [destination] [port]\n"); 1395 if (ret) 1396 exit(1); 1397 } 1398