1 /* $OpenBSD: netcat.c,v 1.111 2013/03/20 09:27:56 sthen 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; /* shutdown() network socket */ 81 int nflag; /* Don't do name look up */ 82 int FreeBSD_Oflag; /* Do not use TCP options */ 83 char *Pflag; /* Proxy username */ 84 char *pflag; /* Localport flag */ 85 int rflag; /* Random ports flag */ 86 char *sflag; /* Source Address */ 87 int tflag; /* Telnet Emulation */ 88 int uflag; /* UDP - Default to TCP */ 89 int vflag; /* Verbosity */ 90 int xflag; /* Socks proxy */ 91 int zflag; /* Port Scan Flag */ 92 int Dflag; /* sodebug */ 93 int Iflag; /* TCP receive buffer size */ 94 int Oflag; /* TCP send buffer size */ 95 int Sflag; /* TCP MD5 signature option */ 96 int Tflag = -1; /* IP Type of Service */ 97 u_int rtableid; 98 99 int timeout = -1; 100 int family = AF_UNSPEC; 101 char *portlist[PORT_MAX+1]; 102 char *unix_dg_tmp_socket; 103 104 void atelnet(int, unsigned char *, unsigned int); 105 void build_ports(char *); 106 void help(void); 107 int local_listen(char *, char *, struct addrinfo); 108 void readwrite(int); 109 int remote_connect(const char *, const char *, struct addrinfo); 110 int timeout_connect(int, const struct sockaddr *, socklen_t); 111 int socks_connect(const char *, const char *, struct addrinfo, 112 const char *, const char *, struct addrinfo, int, const char *); 113 int udptest(int); 114 int unix_bind(char *); 115 int unix_connect(char *); 116 int unix_listen(char *); 117 void set_common_sockopts(int); 118 int map_tos(char *, int *); 119 void report_connect(const struct sockaddr *, socklen_t); 120 void usage(int); 121 122 #ifdef IPSEC 123 void add_ipsec_policy(int, char *); 124 125 char *ipsec_policy[2]; 126 #endif 127 128 int 129 main(int argc, char *argv[]) 130 { 131 int ch, s, ret, socksv, ipsec_count; 132 int numfibs; 133 size_t intsize = sizeof(int); 134 char *host, *uport; 135 struct addrinfo hints; 136 struct servent *sv; 137 socklen_t len; 138 struct sockaddr_storage cliaddr; 139 char *proxy; 140 const char *errstr, *proxyhost = "", *proxyport = NULL; 141 struct addrinfo proxyhints; 142 char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE]; 143 struct option longopts[] = { 144 { "no-tcpopt", no_argument, &FreeBSD_Oflag, 1 }, 145 { NULL, 0, NULL, 0 } 146 }; 147 148 ret = 1; 149 ipsec_count = 0; 150 s = 0; 151 socksv = 5; 152 host = NULL; 153 uport = NULL; 154 sv = NULL; 155 156 while ((ch = getopt_long(argc, argv, 157 "46DdEe:hI:i:klNnoO:P:p:rSs:tT:UuV:vw:X:x:z", 158 longopts, NULL)) != -1) { 159 switch (ch) { 160 case '4': 161 family = AF_INET; 162 break; 163 case '6': 164 family = AF_INET6; 165 break; 166 case 'U': 167 family = AF_UNIX; 168 break; 169 case 'X': 170 if (strcasecmp(optarg, "connect") == 0) 171 socksv = -1; /* HTTP proxy CONNECT */ 172 else if (strcmp(optarg, "4") == 0) 173 socksv = 4; /* SOCKS v.4 */ 174 else if (strcmp(optarg, "5") == 0) 175 socksv = 5; /* SOCKS v.5 */ 176 else 177 errx(1, "unsupported proxy protocol"); 178 break; 179 case 'd': 180 dflag = 1; 181 break; 182 case 'e': 183 #ifdef IPSEC 184 ipsec_policy[ipsec_count++ % 2] = optarg; 185 #else 186 errx(1, "IPsec support unavailable."); 187 #endif 188 break; 189 case 'E': 190 #ifdef IPSEC 191 ipsec_policy[0] = "in ipsec esp/transport//require"; 192 ipsec_policy[1] = "out ipsec esp/transport//require"; 193 #else 194 errx(1, "IPsec support unavailable."); 195 #endif 196 break; 197 case 'h': 198 help(); 199 break; 200 case 'i': 201 iflag = strtonum(optarg, 0, UINT_MAX, &errstr); 202 if (errstr) 203 errx(1, "interval %s: %s", errstr, optarg); 204 break; 205 case 'k': 206 kflag = 1; 207 break; 208 case 'l': 209 lflag = 1; 210 break; 211 case 'N': 212 Nflag = 1; 213 break; 214 case 'n': 215 nflag = 1; 216 break; 217 case 'o': 218 fprintf(stderr, "option -o is deprecated.\n"); 219 break; 220 case 'P': 221 Pflag = optarg; 222 break; 223 case 'p': 224 pflag = optarg; 225 break; 226 case 'r': 227 rflag = 1; 228 break; 229 case 's': 230 sflag = optarg; 231 break; 232 case 't': 233 tflag = 1; 234 break; 235 case 'u': 236 uflag = 1; 237 break; 238 case 'V': 239 if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1) 240 errx(1, "Multiple FIBS not supported"); 241 rtableid = (unsigned int)strtonum(optarg, 0, 242 numfibs - 1, &errstr); 243 if (errstr) 244 errx(1, "rtable %s: %s", errstr, optarg); 245 break; 246 case 'v': 247 vflag = 1; 248 break; 249 case 'w': 250 timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr); 251 if (errstr) 252 errx(1, "timeout %s: %s", errstr, optarg); 253 timeout *= 1000; 254 break; 255 case 'x': 256 xflag = 1; 257 if ((proxy = strdup(optarg)) == NULL) 258 err(1, NULL); 259 break; 260 case 'z': 261 zflag = 1; 262 break; 263 case 'D': 264 Dflag = 1; 265 break; 266 case 'I': 267 Iflag = strtonum(optarg, 1, 65536 << 14, &errstr); 268 if (errstr != NULL) 269 errx(1, "TCP receive window %s: %s", 270 errstr, optarg); 271 break; 272 case 'O': 273 Oflag = strtonum(optarg, 1, 65536 << 14, &errstr); 274 if (errstr != NULL) { 275 if (strcmp(errstr, "invalid") != 0) 276 errx(1, "TCP send window %s: %s", 277 errstr, optarg); 278 } 279 break; 280 case 'S': 281 Sflag = 1; 282 break; 283 case 'T': 284 errstr = NULL; 285 errno = 0; 286 if (map_tos(optarg, &Tflag)) 287 break; 288 if (strlen(optarg) > 1 && optarg[0] == '0' && 289 optarg[1] == 'x') 290 Tflag = (int)strtol(optarg, NULL, 16); 291 else 292 Tflag = (int)strtonum(optarg, 0, 255, 293 &errstr); 294 if (Tflag < 0 || Tflag > 255 || errstr || errno) 295 errx(1, "illegal tos value %s", optarg); 296 break; 297 default: 298 usage(1); 299 } 300 } 301 argc -= optind; 302 argv += optind; 303 304 /* Cruft to make sure options are clean, and used properly. */ 305 if (argv[0] && !argv[1] && family == AF_UNIX) { 306 host = argv[0]; 307 uport = NULL; 308 } else if (argv[0] && !argv[1]) { 309 if (!lflag) 310 usage(1); 311 uport = argv[0]; 312 host = NULL; 313 } else if (argv[0] && argv[1]) { 314 host = argv[0]; 315 uport = argv[1]; 316 } else 317 usage(1); 318 319 if (lflag && sflag) 320 errx(1, "cannot use -s and -l"); 321 if (lflag && pflag) 322 errx(1, "cannot use -p and -l"); 323 if (lflag && zflag) 324 errx(1, "cannot use -z and -l"); 325 if (!lflag && kflag) 326 errx(1, "must use -l with -k"); 327 328 /* Get name of temporary socket for unix datagram client */ 329 if ((family == AF_UNIX) && uflag && !lflag) { 330 if (sflag) { 331 unix_dg_tmp_socket = sflag; 332 } else { 333 strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX", 334 UNIX_DG_TMP_SOCKET_SIZE); 335 if (mktemp(unix_dg_tmp_socket_buf) == NULL) 336 err(1, "mktemp"); 337 unix_dg_tmp_socket = unix_dg_tmp_socket_buf; 338 } 339 } 340 341 /* Initialize addrinfo structure. */ 342 if (family != AF_UNIX) { 343 memset(&hints, 0, sizeof(struct addrinfo)); 344 hints.ai_family = family; 345 hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 346 hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 347 if (nflag) 348 hints.ai_flags |= AI_NUMERICHOST; 349 } 350 351 if (xflag) { 352 if (uflag) 353 errx(1, "no proxy support for UDP mode"); 354 355 if (lflag) 356 errx(1, "no proxy support for listen"); 357 358 if (family == AF_UNIX) 359 errx(1, "no proxy support for unix sockets"); 360 361 /* XXX IPv6 transport to proxy would probably work */ 362 if (family == AF_INET6) 363 errx(1, "no proxy support for IPv6"); 364 365 if (sflag) 366 errx(1, "no proxy support for local source address"); 367 368 proxyhost = strsep(&proxy, ":"); 369 proxyport = proxy; 370 371 memset(&proxyhints, 0, sizeof(struct addrinfo)); 372 proxyhints.ai_family = family; 373 proxyhints.ai_socktype = SOCK_STREAM; 374 proxyhints.ai_protocol = IPPROTO_TCP; 375 if (nflag) 376 proxyhints.ai_flags |= AI_NUMERICHOST; 377 } 378 379 if (lflag) { 380 int connfd; 381 ret = 0; 382 383 if (family == AF_UNIX) { 384 if (uflag) 385 s = unix_bind(host); 386 else 387 s = unix_listen(host); 388 } 389 390 /* Allow only one connection at a time, but stay alive. */ 391 for (;;) { 392 if (family != AF_UNIX) 393 s = local_listen(host, uport, hints); 394 if (s < 0) 395 err(1, NULL); 396 /* 397 * For UDP and -k, don't connect the socket, let it 398 * receive datagrams from multiple socket pairs. 399 */ 400 if (uflag && kflag) 401 readwrite(s); 402 /* 403 * For UDP and not -k, we will use recvfrom() initially 404 * to wait for a caller, then use the regular functions 405 * to talk to the caller. 406 */ 407 else if (uflag && !kflag) { 408 int rv, plen; 409 char buf[16384]; 410 struct sockaddr_storage z; 411 412 len = sizeof(z); 413 plen = 2048; 414 rv = recvfrom(s, buf, plen, MSG_PEEK, 415 (struct sockaddr *)&z, &len); 416 if (rv < 0) 417 err(1, "recvfrom"); 418 419 rv = connect(s, (struct sockaddr *)&z, len); 420 if (rv < 0) 421 err(1, "connect"); 422 423 if (vflag) 424 report_connect((struct sockaddr *)&z, len); 425 426 readwrite(s); 427 } else { 428 len = sizeof(cliaddr); 429 connfd = accept(s, (struct sockaddr *)&cliaddr, 430 &len); 431 if (connfd == -1) { 432 /* For now, all errnos are fatal */ 433 err(1, "accept"); 434 } 435 if (vflag) 436 report_connect((struct sockaddr *)&cliaddr, len); 437 438 readwrite(connfd); 439 close(connfd); 440 } 441 442 if (family != AF_UNIX) 443 close(s); 444 else if (uflag) { 445 if (connect(s, NULL, 0) < 0) 446 err(1, "connect"); 447 } 448 449 if (!kflag) 450 break; 451 } 452 } else if (family == AF_UNIX) { 453 ret = 0; 454 455 if ((s = unix_connect(host)) > 0 && !zflag) { 456 readwrite(s); 457 close(s); 458 } else 459 ret = 1; 460 461 if (uflag) 462 unlink(unix_dg_tmp_socket); 463 exit(ret); 464 465 } else { 466 int i = 0; 467 468 /* Construct the portlist[] array. */ 469 build_ports(uport); 470 471 /* Cycle through portlist, connecting to each port. */ 472 for (i = 0; portlist[i] != NULL; i++) { 473 if (s) 474 close(s); 475 476 if (xflag) 477 s = socks_connect(host, portlist[i], hints, 478 proxyhost, proxyport, proxyhints, socksv, 479 Pflag); 480 else 481 s = remote_connect(host, portlist[i], hints); 482 483 if (s < 0) 484 continue; 485 486 ret = 0; 487 if (vflag || zflag) { 488 /* For UDP, make sure we are connected. */ 489 if (uflag) { 490 if (udptest(s) == -1) { 491 ret = 1; 492 continue; 493 } 494 } 495 496 /* Don't look up port if -n. */ 497 if (nflag) 498 sv = NULL; 499 else { 500 sv = getservbyport( 501 ntohs(atoi(portlist[i])), 502 uflag ? "udp" : "tcp"); 503 } 504 505 fprintf(stderr, 506 "Connection to %s %s port [%s/%s] " 507 "succeeded!\n", host, portlist[i], 508 uflag ? "udp" : "tcp", 509 sv ? sv->s_name : "*"); 510 } 511 if (!zflag) 512 readwrite(s); 513 } 514 } 515 516 if (s) 517 close(s); 518 519 exit(ret); 520 } 521 522 /* 523 * unix_bind() 524 * Returns a unix socket bound to the given path 525 */ 526 int 527 unix_bind(char *path) 528 { 529 struct sockaddr_un sun; 530 int s; 531 532 /* Create unix domain socket. */ 533 if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM, 534 0)) < 0) 535 return (-1); 536 537 memset(&sun, 0, sizeof(struct sockaddr_un)); 538 sun.sun_family = AF_UNIX; 539 540 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 541 sizeof(sun.sun_path)) { 542 close(s); 543 errno = ENAMETOOLONG; 544 return (-1); 545 } 546 547 if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 548 close(s); 549 return (-1); 550 } 551 return (s); 552 } 553 554 /* 555 * unix_connect() 556 * Returns a socket connected to a local unix socket. Returns -1 on failure. 557 */ 558 int 559 unix_connect(char *path) 560 { 561 struct sockaddr_un sun; 562 int s; 563 564 if (uflag) { 565 if ((s = unix_bind(unix_dg_tmp_socket)) < 0) 566 return (-1); 567 } else { 568 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 569 return (-1); 570 } 571 (void)fcntl(s, F_SETFD, 1); 572 573 memset(&sun, 0, sizeof(struct sockaddr_un)); 574 sun.sun_family = AF_UNIX; 575 576 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 577 sizeof(sun.sun_path)) { 578 close(s); 579 errno = ENAMETOOLONG; 580 return (-1); 581 } 582 if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 583 close(s); 584 return (-1); 585 } 586 return (s); 587 588 } 589 590 /* 591 * unix_listen() 592 * Create a unix domain socket, and listen on it. 593 */ 594 int 595 unix_listen(char *path) 596 { 597 int s; 598 if ((s = unix_bind(path)) < 0) 599 return (-1); 600 601 if (listen(s, 5) < 0) { 602 close(s); 603 return (-1); 604 } 605 return (s); 606 } 607 608 /* 609 * remote_connect() 610 * Returns a socket connected to a remote host. Properly binds to a local 611 * port or source address if needed. Returns -1 on failure. 612 */ 613 int 614 remote_connect(const char *host, const char *port, struct addrinfo hints) 615 { 616 struct addrinfo *res, *res0; 617 int s, error, on = 1; 618 619 if ((error = getaddrinfo(host, port, &hints, &res))) 620 errx(1, "getaddrinfo: %s", gai_strerror(error)); 621 622 res0 = res; 623 do { 624 if ((s = socket(res0->ai_family, res0->ai_socktype, 625 res0->ai_protocol)) < 0) 626 continue; 627 #ifdef IPSEC 628 if (ipsec_policy[0] != NULL) 629 add_ipsec_policy(s, ipsec_policy[0]); 630 if (ipsec_policy[1] != NULL) 631 add_ipsec_policy(s, ipsec_policy[1]); 632 #endif 633 634 if (rtableid) { 635 if (setsockopt(s, SOL_SOCKET, SO_SETFIB, &rtableid, 636 sizeof(rtableid)) == -1) 637 err(1, "setsockopt(.., SO_SETFIB, %u, ..)", 638 rtableid); 639 } 640 641 /* Bind to a local port or source address if specified. */ 642 if (sflag || pflag) { 643 struct addrinfo ahints, *ares; 644 645 /* try IP_BINDANY, but don't insist */ 646 setsockopt(s, IPPROTO_IP, IP_BINDANY, &on, sizeof(on)); 647 memset(&ahints, 0, sizeof(struct addrinfo)); 648 ahints.ai_family = res0->ai_family; 649 ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 650 ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 651 ahints.ai_flags = AI_PASSIVE; 652 if ((error = getaddrinfo(sflag, pflag, &ahints, &ares))) 653 errx(1, "getaddrinfo: %s", gai_strerror(error)); 654 655 if (bind(s, (struct sockaddr *)ares->ai_addr, 656 ares->ai_addrlen) < 0) 657 errx(1, "bind failed: %s", strerror(errno)); 658 freeaddrinfo(ares); 659 } 660 661 set_common_sockopts(s); 662 663 if (timeout_connect(s, res0->ai_addr, res0->ai_addrlen) == 0) 664 break; 665 else if (vflag) 666 warn("connect to %s port %s (%s) failed", host, port, 667 uflag ? "udp" : "tcp"); 668 669 close(s); 670 s = -1; 671 } while ((res0 = res0->ai_next) != NULL); 672 673 freeaddrinfo(res); 674 675 return (s); 676 } 677 678 int 679 timeout_connect(int s, const struct sockaddr *name, socklen_t namelen) 680 { 681 struct pollfd pfd; 682 socklen_t optlen; 683 int flags, optval; 684 int ret; 685 686 if (timeout != -1) { 687 flags = fcntl(s, F_GETFL, 0); 688 if (fcntl(s, F_SETFL, flags | O_NONBLOCK) == -1) 689 err(1, "set non-blocking mode"); 690 } 691 692 if ((ret = connect(s, name, namelen)) != 0 && errno == EINPROGRESS) { 693 pfd.fd = s; 694 pfd.events = POLLOUT; 695 if ((ret = poll(&pfd, 1, timeout)) == 1) { 696 optlen = sizeof(optval); 697 if ((ret = getsockopt(s, SOL_SOCKET, SO_ERROR, 698 &optval, &optlen)) == 0) { 699 errno = optval; 700 ret = optval == 0 ? 0 : -1; 701 } 702 } else if (ret == 0) { 703 errno = ETIMEDOUT; 704 ret = -1; 705 } else 706 err(1, "poll failed"); 707 } 708 709 if (timeout != -1 && fcntl(s, F_SETFL, flags) == -1) 710 err(1, "restoring flags"); 711 712 return (ret); 713 } 714 715 /* 716 * local_listen() 717 * Returns a socket listening on a local port, binds to specified source 718 * address. Returns -1 on failure. 719 */ 720 int 721 local_listen(char *host, char *port, struct addrinfo hints) 722 { 723 struct addrinfo *res, *res0; 724 int s, ret, x = 1; 725 int error; 726 727 /* Allow nodename to be null. */ 728 hints.ai_flags |= AI_PASSIVE; 729 730 /* 731 * In the case of binding to a wildcard address 732 * default to binding to an ipv4 address. 733 */ 734 if (host == NULL && hints.ai_family == AF_UNSPEC) 735 hints.ai_family = AF_INET; 736 737 if ((error = getaddrinfo(host, port, &hints, &res))) 738 errx(1, "getaddrinfo: %s", gai_strerror(error)); 739 740 res0 = res; 741 do { 742 if ((s = socket(res0->ai_family, res0->ai_socktype, 743 res0->ai_protocol)) < 0) 744 continue; 745 746 if (rtableid) { 747 ret = setsockopt(s, SOL_SOCKET, SO_SETFIB, &rtableid, 748 sizeof(rtableid)); 749 if (ret == -1) 750 err(1, "setsockopt(.., SO_SETFIB, %u, ..)", 751 rtableid); 752 } 753 754 ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x)); 755 if (ret == -1) 756 err(1, NULL); 757 #ifdef IPSEC 758 if (ipsec_policy[0] != NULL) 759 add_ipsec_policy(s, ipsec_policy[0]); 760 if (ipsec_policy[1] != NULL) 761 add_ipsec_policy(s, ipsec_policy[1]); 762 #endif 763 if (FreeBSD_Oflag) { 764 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 765 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 766 err(1, "disable TCP options"); 767 } 768 769 if (bind(s, (struct sockaddr *)res0->ai_addr, 770 res0->ai_addrlen) == 0) 771 break; 772 773 close(s); 774 s = -1; 775 } while ((res0 = res0->ai_next) != NULL); 776 777 if (!uflag && s != -1) { 778 if (listen(s, 1) < 0) 779 err(1, "listen"); 780 } 781 782 freeaddrinfo(res); 783 784 return (s); 785 } 786 787 /* 788 * readwrite() 789 * Loop that polls on the network file descriptor and stdin. 790 */ 791 void 792 readwrite(int nfd) 793 { 794 struct pollfd pfd[2]; 795 unsigned char buf[16384]; 796 int n, wfd = fileno(stdin); 797 int lfd = fileno(stdout); 798 int plen; 799 800 plen = 2048; 801 802 /* Setup Network FD */ 803 pfd[0].fd = nfd; 804 pfd[0].events = POLLIN; 805 806 /* Set up STDIN FD. */ 807 pfd[1].fd = wfd; 808 pfd[1].events = POLLIN; 809 810 while (pfd[0].fd != -1) { 811 if (iflag) 812 sleep(iflag); 813 814 if ((n = poll(pfd, 2 - dflag, timeout)) < 0) { 815 close(nfd); 816 err(1, "Polling Error"); 817 } 818 819 if (n == 0) 820 return; 821 822 if (pfd[0].revents & POLLIN) { 823 if ((n = read(nfd, buf, plen)) < 0) 824 return; 825 else if (n == 0) { 826 shutdown(nfd, SHUT_RD); 827 pfd[0].fd = -1; 828 pfd[0].events = 0; 829 } else { 830 if (tflag) 831 atelnet(nfd, buf, n); 832 if (atomicio(vwrite, lfd, buf, n) != n) 833 return; 834 } 835 } 836 837 if (!dflag && pfd[1].revents & POLLIN) { 838 if ((n = read(wfd, buf, plen)) < 0) 839 return; 840 else if (n == 0) { 841 if (Nflag) 842 shutdown(nfd, SHUT_WR); 843 pfd[1].fd = -1; 844 pfd[1].events = 0; 845 } else { 846 if (atomicio(vwrite, nfd, buf, n) != n) 847 return; 848 } 849 } 850 } 851 } 852 853 /* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */ 854 void 855 atelnet(int nfd, unsigned char *buf, unsigned int size) 856 { 857 unsigned char *p, *end; 858 unsigned char obuf[4]; 859 860 if (size < 3) 861 return; 862 end = buf + size - 2; 863 864 for (p = buf; p < end; p++) { 865 if (*p != IAC) 866 continue; 867 868 obuf[0] = IAC; 869 p++; 870 if ((*p == WILL) || (*p == WONT)) 871 obuf[1] = DONT; 872 else if ((*p == DO) || (*p == DONT)) 873 obuf[1] = WONT; 874 else 875 continue; 876 877 p++; 878 obuf[2] = *p; 879 if (atomicio(vwrite, nfd, obuf, 3) != 3) 880 warn("Write Error!"); 881 } 882 } 883 884 /* 885 * build_ports() 886 * Build an array of ports in portlist[], listing each port 887 * that we should try to connect to. 888 */ 889 void 890 build_ports(char *p) 891 { 892 const char *errstr; 893 char *n; 894 int hi, lo, cp; 895 int x = 0; 896 897 if ((n = strchr(p, '-')) != NULL) { 898 *n = '\0'; 899 n++; 900 901 /* Make sure the ports are in order: lowest->highest. */ 902 hi = strtonum(n, 1, PORT_MAX, &errstr); 903 if (errstr) 904 errx(1, "port number %s: %s", errstr, n); 905 lo = strtonum(p, 1, PORT_MAX, &errstr); 906 if (errstr) 907 errx(1, "port number %s: %s", errstr, p); 908 909 if (lo > hi) { 910 cp = hi; 911 hi = lo; 912 lo = cp; 913 } 914 915 /* Load ports sequentially. */ 916 for (cp = lo; cp <= hi; cp++) { 917 portlist[x] = calloc(1, PORT_MAX_LEN); 918 if (portlist[x] == NULL) 919 err(1, NULL); 920 snprintf(portlist[x], PORT_MAX_LEN, "%d", cp); 921 x++; 922 } 923 924 /* Randomly swap ports. */ 925 if (rflag) { 926 int y; 927 char *c; 928 929 for (x = 0; x <= (hi - lo); x++) { 930 y = (arc4random() & 0xFFFF) % (hi - lo); 931 c = portlist[x]; 932 portlist[x] = portlist[y]; 933 portlist[y] = c; 934 } 935 } 936 } else { 937 hi = strtonum(p, 1, PORT_MAX, &errstr); 938 if (errstr) 939 errx(1, "port number %s: %s", errstr, p); 940 portlist[0] = strdup(p); 941 if (portlist[0] == NULL) 942 err(1, NULL); 943 } 944 } 945 946 /* 947 * udptest() 948 * Do a few writes to see if the UDP port is there. 949 * Fails once PF state table is full. 950 */ 951 int 952 udptest(int s) 953 { 954 int i, ret; 955 956 for (i = 0; i <= 3; i++) { 957 if (write(s, "X", 1) == 1) 958 ret = 1; 959 else 960 ret = -1; 961 } 962 return (ret); 963 } 964 965 void 966 set_common_sockopts(int s) 967 { 968 int x = 1; 969 970 if (Sflag) { 971 if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG, 972 &x, sizeof(x)) == -1) 973 err(1, NULL); 974 } 975 if (Dflag) { 976 if (setsockopt(s, SOL_SOCKET, SO_DEBUG, 977 &x, sizeof(x)) == -1) 978 err(1, NULL); 979 } 980 if (Tflag != -1) { 981 if (setsockopt(s, IPPROTO_IP, IP_TOS, 982 &Tflag, sizeof(Tflag)) == -1) 983 err(1, "set IP ToS"); 984 } 985 if (Iflag) { 986 if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, 987 &Iflag, sizeof(Iflag)) == -1) 988 err(1, "set TCP receive buffer size"); 989 } 990 if (Oflag) { 991 if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, 992 &Oflag, sizeof(Oflag)) == -1) 993 err(1, "set TCP send buffer size"); 994 } 995 if (FreeBSD_Oflag) { 996 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 997 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 998 err(1, "disable TCP options"); 999 } 1000 } 1001 1002 int 1003 map_tos(char *s, int *val) 1004 { 1005 /* DiffServ Codepoints and other TOS mappings */ 1006 const struct toskeywords { 1007 const char *keyword; 1008 int val; 1009 } *t, toskeywords[] = { 1010 { "af11", IPTOS_DSCP_AF11 }, 1011 { "af12", IPTOS_DSCP_AF12 }, 1012 { "af13", IPTOS_DSCP_AF13 }, 1013 { "af21", IPTOS_DSCP_AF21 }, 1014 { "af22", IPTOS_DSCP_AF22 }, 1015 { "af23", IPTOS_DSCP_AF23 }, 1016 { "af31", IPTOS_DSCP_AF31 }, 1017 { "af32", IPTOS_DSCP_AF32 }, 1018 { "af33", IPTOS_DSCP_AF33 }, 1019 { "af41", IPTOS_DSCP_AF41 }, 1020 { "af42", IPTOS_DSCP_AF42 }, 1021 { "af43", IPTOS_DSCP_AF43 }, 1022 { "critical", IPTOS_PREC_CRITIC_ECP }, 1023 { "cs0", IPTOS_DSCP_CS0 }, 1024 { "cs1", IPTOS_DSCP_CS1 }, 1025 { "cs2", IPTOS_DSCP_CS2 }, 1026 { "cs3", IPTOS_DSCP_CS3 }, 1027 { "cs4", IPTOS_DSCP_CS4 }, 1028 { "cs5", IPTOS_DSCP_CS5 }, 1029 { "cs6", IPTOS_DSCP_CS6 }, 1030 { "cs7", IPTOS_DSCP_CS7 }, 1031 { "ef", IPTOS_DSCP_EF }, 1032 { "inetcontrol", IPTOS_PREC_INTERNETCONTROL }, 1033 { "lowdelay", IPTOS_LOWDELAY }, 1034 { "netcontrol", IPTOS_PREC_NETCONTROL }, 1035 { "reliability", IPTOS_RELIABILITY }, 1036 { "throughput", IPTOS_THROUGHPUT }, 1037 { NULL, -1 }, 1038 }; 1039 1040 for (t = toskeywords; t->keyword != NULL; t++) { 1041 if (strcmp(s, t->keyword) == 0) { 1042 *val = t->val; 1043 return (1); 1044 } 1045 } 1046 1047 return (0); 1048 } 1049 1050 void 1051 report_connect(const struct sockaddr *sa, socklen_t salen) 1052 { 1053 char remote_host[NI_MAXHOST]; 1054 char remote_port[NI_MAXSERV]; 1055 int herr; 1056 int flags = NI_NUMERICSERV; 1057 1058 if (nflag) 1059 flags |= NI_NUMERICHOST; 1060 1061 if ((herr = getnameinfo(sa, salen, 1062 remote_host, sizeof(remote_host), 1063 remote_port, sizeof(remote_port), 1064 flags)) != 0) { 1065 if (herr == EAI_SYSTEM) 1066 err(1, "getnameinfo"); 1067 else 1068 errx(1, "getnameinfo: %s", gai_strerror(herr)); 1069 } 1070 1071 fprintf(stderr, 1072 "Connection from %s %s " 1073 "received!\n", remote_host, remote_port); 1074 } 1075 1076 void 1077 help(void) 1078 { 1079 usage(0); 1080 fprintf(stderr, "\tCommand Summary:\n\ 1081 \t-4 Use IPv4\n\ 1082 \t-6 Use IPv6\n\ 1083 \t-D Enable the debug socket option\n\ 1084 \t-d Detach from stdin\n"); 1085 #ifdef IPSEC 1086 fprintf(stderr, "\ 1087 \t-E Use IPsec ESP\n\ 1088 \t-e policy Use specified IPsec policy\n"); 1089 #endif 1090 fprintf(stderr, "\ 1091 \t-h This help text\n\ 1092 \t-I length TCP receive buffer length\n\ 1093 \t-i secs\t Delay interval for lines sent, ports scanned\n\ 1094 \t-k Keep inbound sockets open for multiple connects\n\ 1095 \t-l Listen mode, for inbound connects\n\ 1096 \t-N Shutdown the network socket after EOF on stdin\n\ 1097 \t-n Suppress name/port resolutions\n\ 1098 \t--no-tcpopt Disable TCP options\n\ 1099 \t-O length TCP send buffer length\n\ 1100 \t-P proxyuser\tUsername for proxy authentication\n\ 1101 \t-p port\t Specify local port for remote connects\n\ 1102 \t-r Randomize remote ports\n\ 1103 \t-S Enable the TCP MD5 signature option\n\ 1104 \t-s addr\t Local source address\n\ 1105 \t-T toskeyword\tSet IP Type of Service\n\ 1106 \t-t Answer TELNET negotiation\n\ 1107 \t-U Use UNIX domain socket\n\ 1108 \t-u UDP mode\n\ 1109 \t-V rtable Specify alternate routing table\n\ 1110 \t-v Verbose\n\ 1111 \t-w secs\t Timeout for connects and final net reads\n\ 1112 \t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\ 1113 \t-x addr[:port]\tSpecify proxy address and port\n\ 1114 \t-z Zero-I/O mode [used for scanning]\n\ 1115 Port numbers can be individual or ranges: lo-hi [inclusive]\n"); 1116 #ifdef IPSEC 1117 fprintf(stderr, "See ipsec_set_policy(3) for -e argument format\n"); 1118 #endif 1119 exit(1); 1120 } 1121 1122 #ifdef IPSEC 1123 void 1124 add_ipsec_policy(int s, char *policy) 1125 { 1126 char *raw; 1127 int e; 1128 1129 raw = ipsec_set_policy(policy, strlen(policy)); 1130 if (raw == NULL) 1131 errx(1, "ipsec_set_policy `%s': %s", policy, 1132 ipsec_strerror()); 1133 e = setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, raw, 1134 ipsec_get_policylen(raw)); 1135 if (e < 0) 1136 err(1, "ipsec policy cannot be configured"); 1137 free(raw); 1138 if (vflag) 1139 fprintf(stderr, "ipsec policy configured: `%s'\n", policy); 1140 return; 1141 } 1142 #endif /* IPSEC */ 1143 1144 void 1145 usage(int ret) 1146 { 1147 fprintf(stderr, 1148 #ifdef IPSEC 1149 "usage: nc [-46DdEhklNnrStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n" 1150 #else 1151 "usage: nc [-46DdhklNnrStUuvz] [-I length] [-i interval] [-O length]\n" 1152 #endif 1153 "\t [-P proxy_username] [-p source_port] [-s source] [-T ToS]\n" 1154 "\t [-V rtable] [-w timeout] [-X proxy_protocol]\n" 1155 "\t [-x proxy_address[:port]] [destination] [port]\n"); 1156 if (ret) 1157 exit(1); 1158 } 1159