1 /* $OpenBSD: netcat.c,v 1.95 2010/02/27 00:58:56 nicm 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 74 /* Command Line Options */ 75 int Eflag; /* Use IPsec ESP */ 76 int dflag; /* detached, no stdin */ 77 unsigned int iflag; /* Interval Flag */ 78 int jflag; /* use jumbo frames if we can */ 79 int kflag; /* More than one connect */ 80 int lflag; /* Bind to local port */ 81 int nflag; /* Don't do name look up */ 82 int oflag; /* Once only: stop on EOF */ 83 int FreeBSD_Oflag; /* Do not use TCP options */ 84 char *Pflag; /* Proxy username */ 85 char *pflag; /* Localport flag */ 86 int rflag; /* Random ports flag */ 87 char *sflag; /* Source Address */ 88 int tflag; /* Telnet Emulation */ 89 int uflag; /* UDP - Default to TCP */ 90 int vflag; /* Verbosity */ 91 int xflag; /* Socks proxy */ 92 int zflag; /* Port Scan Flag */ 93 int Dflag; /* sodebug */ 94 int Iflag; /* TCP receive buffer size */ 95 int Oflag; /* TCP send buffer size */ 96 int Sflag; /* TCP MD5 signature option */ 97 int Tflag = -1; /* IP Type of Service */ 98 u_int rdomain; 99 100 int timeout = -1; 101 int family = AF_UNSPEC; 102 char *portlist[PORT_MAX+1]; 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 socks_connect(const char *, const char *, struct addrinfo, 111 const char *, const char *, struct addrinfo, int, const char *); 112 int udptest(int); 113 int unix_connect(char *); 114 int unix_listen(char *); 115 void set_common_sockopts(int); 116 int parse_iptos(char *); 117 void usage(int); 118 119 #ifdef IPSEC 120 void add_ipsec_policy(int, char *); 121 122 char *ipsec_policy[2]; 123 #endif 124 125 int 126 main(int argc, char *argv[]) 127 { 128 int ch, s, ret, socksv, ipsec_count; 129 int numfibs; 130 size_t intsize = sizeof(int); 131 char *host, *uport; 132 struct addrinfo hints; 133 struct servent *sv; 134 socklen_t len; 135 struct sockaddr_storage cliaddr; 136 char *proxy; 137 const char *errstr, *proxyhost = "", *proxyport = NULL; 138 struct addrinfo proxyhints; 139 struct option longopts[] = { 140 { "no-tcpopt", no_argument, &FreeBSD_Oflag, 1 }, 141 { NULL, 0, NULL, 0 } 142 }; 143 144 rdomain = 0; 145 ret = 1; 146 ipsec_count = 0; 147 s = 0; 148 socksv = 5; 149 host = NULL; 150 uport = NULL; 151 sv = NULL; 152 153 while ((ch = getopt_long(argc, argv, 154 "46DdEe:hI:i:jklnO:oP:p:rSs:tT:UuV:vw:X:x:z", 155 longopts, NULL)) != -1) { 156 switch (ch) { 157 case '4': 158 family = AF_INET; 159 break; 160 case '6': 161 family = AF_INET6; 162 break; 163 case 'U': 164 family = AF_UNIX; 165 break; 166 case 'X': 167 if (strcasecmp(optarg, "connect") == 0) 168 socksv = -1; /* HTTP proxy CONNECT */ 169 else if (strcmp(optarg, "4") == 0) 170 socksv = 4; /* SOCKS v.4 */ 171 else if (strcmp(optarg, "5") == 0) 172 socksv = 5; /* SOCKS v.5 */ 173 else 174 errx(1, "unsupported proxy protocol"); 175 break; 176 case 'd': 177 dflag = 1; 178 break; 179 case 'e': 180 #ifdef IPSEC 181 ipsec_policy[ipsec_count++ % 2] = optarg; 182 #else 183 errx(1, "IPsec support unavailable."); 184 #endif 185 break; 186 case 'E': 187 #ifdef IPSEC 188 ipsec_policy[0] = "in ipsec esp/transport//require"; 189 ipsec_policy[1] = "out ipsec esp/transport//require"; 190 #else 191 errx(1, "IPsec support unavailable."); 192 #endif 193 break; 194 case 'h': 195 help(); 196 break; 197 case 'i': 198 iflag = strtonum(optarg, 0, UINT_MAX, &errstr); 199 if (errstr) 200 errx(1, "interval %s: %s", errstr, optarg); 201 break; 202 #ifdef SO_JUMBO 203 case 'j': 204 jflag = 1; 205 break; 206 #endif 207 case 'k': 208 kflag = 1; 209 break; 210 case 'l': 211 lflag = 1; 212 break; 213 case 'n': 214 nflag = 1; 215 break; 216 case 'o': 217 oflag = 1; 218 break; 219 case 'P': 220 Pflag = optarg; 221 break; 222 case 'p': 223 pflag = optarg; 224 break; 225 case 'r': 226 rflag = 1; 227 break; 228 case 's': 229 sflag = optarg; 230 break; 231 case 't': 232 tflag = 1; 233 break; 234 case 'u': 235 uflag = 1; 236 break; 237 case 'V': 238 if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1) 239 errx(1, "Multiple FIBS not supported"); 240 rdomain = (unsigned int)strtonum(optarg, 0, 241 numfibs - 1, &errstr); 242 if (errstr) 243 errx(1, "FIB %s: %s", errstr, optarg); 244 break; 245 case 'v': 246 vflag = 1; 247 break; 248 case 'w': 249 timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr); 250 if (errstr) 251 errx(1, "timeout %s: %s", errstr, optarg); 252 timeout *= 1000; 253 break; 254 case 'x': 255 xflag = 1; 256 if ((proxy = strdup(optarg)) == NULL) 257 err(1, NULL); 258 break; 259 case 'z': 260 zflag = 1; 261 break; 262 case 'D': 263 Dflag = 1; 264 break; 265 case 'I': 266 Iflag = strtonum(optarg, 1, 65536 << 14, &errstr); 267 if (errstr != NULL) 268 errx(1, "TCP receive window %s: %s", 269 errstr, optarg); 270 break; 271 case 'O': 272 Oflag = strtonum(optarg, 1, 65536 << 14, &errstr); 273 if (errstr != NULL) { 274 if (strcmp(errstr, "invalid") != 0) 275 errx(1, "TCP send window %s: %s", 276 errstr, optarg); 277 } 278 break; 279 case 'S': 280 Sflag = 1; 281 break; 282 case 'T': 283 Tflag = parse_iptos(optarg); 284 break; 285 case 0: 286 break; 287 default: 288 usage(1); 289 } 290 } 291 argc -= optind; 292 argv += optind; 293 294 /* Cruft to make sure options are clean, and used properly. */ 295 if (argv[0] && !argv[1] && family == AF_UNIX) { 296 if (uflag) 297 errx(1, "cannot use -u and -U"); 298 host = argv[0]; 299 uport = NULL; 300 } else if (argv[0] && !argv[1]) { 301 if (!lflag) 302 usage(1); 303 uport = argv[0]; 304 host = NULL; 305 } else if (argv[0] && argv[1]) { 306 host = argv[0]; 307 uport = argv[1]; 308 } else 309 usage(1); 310 311 if (lflag && sflag) 312 errx(1, "cannot use -s and -l"); 313 if (lflag && pflag) 314 errx(1, "cannot use -p and -l"); 315 if (lflag && zflag) 316 errx(1, "cannot use -z and -l"); 317 if (!lflag && kflag) 318 errx(1, "must use -l with -k"); 319 320 /* Initialize addrinfo structure. */ 321 if (family != AF_UNIX) { 322 memset(&hints, 0, sizeof(struct addrinfo)); 323 hints.ai_family = family; 324 hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 325 hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 326 if (nflag) 327 hints.ai_flags |= AI_NUMERICHOST; 328 } 329 330 if (xflag) { 331 if (uflag) 332 errx(1, "no proxy support for UDP mode"); 333 334 if (lflag) 335 errx(1, "no proxy support for listen"); 336 337 if (family == AF_UNIX) 338 errx(1, "no proxy support for unix sockets"); 339 340 /* XXX IPv6 transport to proxy would probably work */ 341 if (family == AF_INET6) 342 errx(1, "no proxy support for IPv6"); 343 344 if (sflag) 345 errx(1, "no proxy support for local source address"); 346 347 proxyhost = strsep(&proxy, ":"); 348 proxyport = proxy; 349 350 memset(&proxyhints, 0, sizeof(struct addrinfo)); 351 proxyhints.ai_family = family; 352 proxyhints.ai_socktype = SOCK_STREAM; 353 proxyhints.ai_protocol = IPPROTO_TCP; 354 if (nflag) 355 proxyhints.ai_flags |= AI_NUMERICHOST; 356 } 357 358 if (lflag) { 359 int connfd; 360 ret = 0; 361 362 if (family == AF_UNIX) 363 s = unix_listen(host); 364 365 /* Allow only one connection at a time, but stay alive. */ 366 for (;;) { 367 if (family != AF_UNIX) 368 s = local_listen(host, uport, hints); 369 if (s < 0) 370 err(1, NULL); 371 /* 372 * For UDP, we will use recvfrom() initially 373 * to wait for a caller, then use the regular 374 * functions to talk to the caller. 375 */ 376 if (uflag) { 377 int rv, plen; 378 char buf[8192]; 379 struct sockaddr_storage z; 380 381 len = sizeof(z); 382 plen = jflag ? 8192 : 1024; 383 rv = recvfrom(s, buf, plen, MSG_PEEK, 384 (struct sockaddr *)&z, &len); 385 if (rv < 0) 386 err(1, "recvfrom"); 387 388 rv = connect(s, (struct sockaddr *)&z, len); 389 if (rv < 0) 390 err(1, "connect"); 391 392 connfd = s; 393 } else { 394 len = sizeof(cliaddr); 395 connfd = accept(s, (struct sockaddr *)&cliaddr, 396 &len); 397 } 398 399 readwrite(connfd); 400 close(connfd); 401 if (family != AF_UNIX) 402 close(s); 403 404 if (!kflag) 405 break; 406 } 407 } else if (family == AF_UNIX) { 408 ret = 0; 409 410 if ((s = unix_connect(host)) > 0 && !zflag) { 411 readwrite(s); 412 close(s); 413 } else 414 ret = 1; 415 416 exit(ret); 417 418 } else { 419 int i = 0; 420 421 /* Construct the portlist[] array. */ 422 build_ports(uport); 423 424 /* Cycle through portlist, connecting to each port. */ 425 for (i = 0; portlist[i] != NULL; i++) { 426 if (s) 427 close(s); 428 429 if (xflag) 430 s = socks_connect(host, portlist[i], hints, 431 proxyhost, proxyport, proxyhints, socksv, 432 Pflag); 433 else 434 s = remote_connect(host, portlist[i], hints); 435 436 if (s < 0) 437 continue; 438 439 ret = 0; 440 if (vflag || zflag) { 441 /* For UDP, make sure we are connected. */ 442 if (uflag) { 443 if (udptest(s) == -1) { 444 ret = 1; 445 continue; 446 } 447 } 448 449 /* Don't look up port if -n. */ 450 if (nflag) 451 sv = NULL; 452 else { 453 sv = getservbyport( 454 ntohs(atoi(portlist[i])), 455 uflag ? "udp" : "tcp"); 456 } 457 458 fprintf(stderr, 459 "Connection to %s %s port [%s/%s] " 460 "succeeded!\n", host, portlist[i], 461 uflag ? "udp" : "tcp", 462 sv ? sv->s_name : "*"); 463 } 464 if (!zflag) 465 readwrite(s); 466 } 467 } 468 469 if (s) 470 close(s); 471 472 exit(ret); 473 } 474 475 /* 476 * unix_connect() 477 * Returns a socket connected to a local unix socket. Returns -1 on failure. 478 */ 479 int 480 unix_connect(char *path) 481 { 482 struct sockaddr_un sun; 483 int s; 484 485 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 486 return (-1); 487 (void)fcntl(s, F_SETFD, 1); 488 489 memset(&sun, 0, sizeof(struct sockaddr_un)); 490 sun.sun_family = AF_UNIX; 491 492 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 493 sizeof(sun.sun_path)) { 494 close(s); 495 errno = ENAMETOOLONG; 496 return (-1); 497 } 498 if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 499 close(s); 500 return (-1); 501 } 502 return (s); 503 504 } 505 506 /* 507 * unix_listen() 508 * Create a unix domain socket, and listen on it. 509 */ 510 int 511 unix_listen(char *path) 512 { 513 struct sockaddr_un sun; 514 int s; 515 516 /* Create unix domain socket. */ 517 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 518 return (-1); 519 520 memset(&sun, 0, sizeof(struct sockaddr_un)); 521 sun.sun_family = AF_UNIX; 522 523 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 524 sizeof(sun.sun_path)) { 525 close(s); 526 errno = ENAMETOOLONG; 527 return (-1); 528 } 529 530 if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 531 close(s); 532 return (-1); 533 } 534 535 if (listen(s, 5) < 0) { 536 close(s); 537 return (-1); 538 } 539 return (s); 540 } 541 542 /* 543 * remote_connect() 544 * Returns a socket connected to a remote host. Properly binds to a local 545 * port or source address if needed. Returns -1 on failure. 546 */ 547 int 548 remote_connect(const char *host, const char *port, struct addrinfo hints) 549 { 550 struct addrinfo *res, *res0; 551 int s, error, on = 1; 552 553 if ((error = getaddrinfo(host, port, &hints, &res))) 554 errx(1, "getaddrinfo: %s", gai_strerror(error)); 555 556 res0 = res; 557 do { 558 if ((s = socket(res0->ai_family, res0->ai_socktype, 559 res0->ai_protocol)) < 0) 560 continue; 561 #ifdef IPSEC 562 if (ipsec_policy[0] != NULL) 563 add_ipsec_policy(s, ipsec_policy[0]); 564 if (ipsec_policy[1] != NULL) 565 add_ipsec_policy(s, ipsec_policy[1]); 566 #endif 567 568 if (rdomain) { 569 if (setfib(rdomain) == -1) 570 err(1, "setfib"); 571 } 572 573 /* Bind to a local port or source address if specified. */ 574 if (sflag || pflag) { 575 struct addrinfo ahints, *ares; 576 577 #ifdef SO_BINDANY 578 /* try SO_BINDANY, but don't insist */ 579 setsockopt(s, SOL_SOCKET, SO_BINDANY, &on, sizeof(on)); 580 #endif 581 memset(&ahints, 0, sizeof(struct addrinfo)); 582 ahints.ai_family = res0->ai_family; 583 ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 584 ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 585 ahints.ai_flags = AI_PASSIVE; 586 if ((error = getaddrinfo(sflag, pflag, &ahints, &ares))) 587 errx(1, "getaddrinfo: %s", gai_strerror(error)); 588 589 if (bind(s, (struct sockaddr *)ares->ai_addr, 590 ares->ai_addrlen) < 0) 591 errx(1, "bind failed: %s", strerror(errno)); 592 freeaddrinfo(ares); 593 } 594 595 set_common_sockopts(s); 596 597 if (connect(s, res0->ai_addr, res0->ai_addrlen) == 0) 598 break; 599 else if (vflag) 600 warn("connect to %s port %s (%s) failed", host, port, 601 uflag ? "udp" : "tcp"); 602 603 close(s); 604 s = -1; 605 } while ((res0 = res0->ai_next) != NULL); 606 607 freeaddrinfo(res); 608 609 return (s); 610 } 611 612 /* 613 * local_listen() 614 * Returns a socket listening on a local port, binds to specified source 615 * address. Returns -1 on failure. 616 */ 617 int 618 local_listen(char *host, char *port, struct addrinfo hints) 619 { 620 struct addrinfo *res, *res0; 621 int s, ret, x = 1; 622 int error; 623 624 /* Allow nodename to be null. */ 625 hints.ai_flags |= AI_PASSIVE; 626 627 /* 628 * In the case of binding to a wildcard address 629 * default to binding to an ipv4 address. 630 */ 631 if (host == NULL && hints.ai_family == AF_UNSPEC) 632 hints.ai_family = AF_INET; 633 634 if ((error = getaddrinfo(host, port, &hints, &res))) 635 errx(1, "getaddrinfo: %s", gai_strerror(error)); 636 637 res0 = res; 638 do { 639 if ((s = socket(res0->ai_family, res0->ai_socktype, 640 res0->ai_protocol)) < 0) 641 continue; 642 643 if (rdomain) { 644 if (setfib(rdomain) == -1) 645 err(1, "setfib"); 646 } 647 648 ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x)); 649 if (ret == -1) 650 err(1, NULL); 651 #ifdef IPSEC 652 if (ipsec_policy[0] != NULL) 653 add_ipsec_policy(s, ipsec_policy[0]); 654 if (ipsec_policy[1] != NULL) 655 add_ipsec_policy(s, ipsec_policy[1]); 656 #endif 657 if (FreeBSD_Oflag) { 658 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 659 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 660 err(1, "disable TCP options"); 661 } 662 663 if (bind(s, (struct sockaddr *)res0->ai_addr, 664 res0->ai_addrlen) == 0) 665 break; 666 667 close(s); 668 s = -1; 669 } while ((res0 = res0->ai_next) != NULL); 670 671 if (!uflag && s != -1) { 672 if (listen(s, 1) < 0) 673 err(1, "listen"); 674 } 675 676 freeaddrinfo(res); 677 678 return (s); 679 } 680 681 /* 682 * readwrite() 683 * Loop that polls on the network file descriptor and stdin. 684 */ 685 void 686 readwrite(int nfd) 687 { 688 struct pollfd pfd[2]; 689 unsigned char buf[8192]; 690 int n, wfd = fileno(stdin); 691 int lfd = fileno(stdout); 692 int plen; 693 694 plen = jflag ? 8192 : 1024; 695 696 /* Setup Network FD */ 697 pfd[0].fd = nfd; 698 pfd[0].events = POLLIN; 699 700 /* Set up STDIN FD. */ 701 pfd[1].fd = wfd; 702 pfd[1].events = POLLIN; 703 704 while (pfd[0].fd != -1) { 705 if (iflag) 706 sleep(iflag); 707 708 if ((n = poll(pfd, 2 - dflag, timeout)) < 0) { 709 close(nfd); 710 err(1, "Polling Error"); 711 } 712 713 if (n == 0) 714 return; 715 716 if (pfd[0].revents & POLLIN) { 717 if ((n = read(nfd, buf, plen)) < 0) 718 return; 719 else if (n == 0) { 720 shutdown(nfd, SHUT_RD); 721 pfd[0].fd = -1; 722 pfd[0].events = 0; 723 } else { 724 if (tflag) 725 atelnet(nfd, buf, n); 726 if (atomicio(vwrite, lfd, buf, n) != n) 727 return; 728 } 729 } 730 731 if (!dflag && pfd[1].revents & POLLIN) { 732 if ((n = read(wfd, buf, plen)) < 0 || 733 (oflag && n == 0)) { 734 return; 735 } else if (n == 0) { 736 shutdown(nfd, SHUT_WR); 737 pfd[1].fd = -1; 738 pfd[1].events = 0; 739 } else { 740 if (atomicio(vwrite, nfd, buf, n) != n) 741 return; 742 } 743 } 744 } 745 } 746 747 /* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */ 748 void 749 atelnet(int nfd, unsigned char *buf, unsigned int size) 750 { 751 unsigned char *p, *end; 752 unsigned char obuf[4]; 753 754 if (size < 3) 755 return; 756 end = buf + size - 2; 757 758 for (p = buf; p < end; p++) { 759 if (*p != IAC) 760 continue; 761 762 obuf[0] = IAC; 763 p++; 764 if ((*p == WILL) || (*p == WONT)) 765 obuf[1] = DONT; 766 else if ((*p == DO) || (*p == DONT)) 767 obuf[1] = WONT; 768 else 769 continue; 770 771 p++; 772 obuf[2] = *p; 773 if (atomicio(vwrite, nfd, obuf, 3) != 3) 774 warn("Write Error!"); 775 } 776 } 777 778 /* 779 * build_ports() 780 * Build an array or ports in portlist[], listing each port 781 * that we should try to connect to. 782 */ 783 void 784 build_ports(char *p) 785 { 786 const char *errstr; 787 char *n; 788 int hi, lo, cp; 789 int x = 0; 790 791 if ((n = strchr(p, '-')) != NULL) { 792 if (lflag) 793 errx(1, "Cannot use -l with multiple ports!"); 794 795 *n = '\0'; 796 n++; 797 798 /* Make sure the ports are in order: lowest->highest. */ 799 hi = strtonum(n, 1, PORT_MAX, &errstr); 800 if (errstr) 801 errx(1, "port number %s: %s", errstr, n); 802 lo = strtonum(p, 1, PORT_MAX, &errstr); 803 if (errstr) 804 errx(1, "port number %s: %s", errstr, p); 805 806 if (lo > hi) { 807 cp = hi; 808 hi = lo; 809 lo = cp; 810 } 811 812 /* Load ports sequentially. */ 813 for (cp = lo; cp <= hi; cp++) { 814 portlist[x] = calloc(1, PORT_MAX_LEN); 815 if (portlist[x] == NULL) 816 err(1, NULL); 817 snprintf(portlist[x], PORT_MAX_LEN, "%d", cp); 818 x++; 819 } 820 821 /* Randomly swap ports. */ 822 if (rflag) { 823 int y; 824 char *c; 825 826 for (x = 0; x <= (hi - lo); x++) { 827 y = (arc4random() & 0xFFFF) % (hi - lo); 828 c = portlist[x]; 829 portlist[x] = portlist[y]; 830 portlist[y] = c; 831 } 832 } 833 } else { 834 hi = strtonum(p, 1, PORT_MAX, &errstr); 835 if (errstr) 836 errx(1, "port number %s: %s", errstr, p); 837 portlist[0] = calloc(1, PORT_MAX_LEN); 838 if (portlist[0] == NULL) 839 err(1, NULL); 840 portlist[0] = p; 841 } 842 } 843 844 /* 845 * udptest() 846 * Do a few writes to see if the UDP port is there. 847 * XXX - Better way of doing this? Doesn't work for IPv6. 848 * Also fails after around 100 ports checked. 849 */ 850 int 851 udptest(int s) 852 { 853 int i, ret; 854 855 for (i = 0; i <= 3; i++) { 856 if (write(s, "X", 1) == 1) 857 ret = 1; 858 else 859 ret = -1; 860 } 861 return (ret); 862 } 863 864 void 865 set_common_sockopts(int s) 866 { 867 int x = 1; 868 869 if (Sflag) { 870 if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG, 871 &x, sizeof(x)) == -1) 872 err(1, NULL); 873 } 874 if (Dflag) { 875 if (setsockopt(s, SOL_SOCKET, SO_DEBUG, 876 &x, sizeof(x)) == -1) 877 err(1, NULL); 878 } 879 #ifdef SO_JUMBO 880 if (jflag) { 881 if (setsockopt(s, SOL_SOCKET, SO_JUMBO, 882 &x, sizeof(x)) == -1) 883 err(1, NULL); 884 } 885 #endif 886 if (Tflag != -1) { 887 if (setsockopt(s, IPPROTO_IP, IP_TOS, 888 &Tflag, sizeof(Tflag)) == -1) 889 err(1, "set IP ToS"); 890 } 891 if (Iflag) { 892 if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, 893 &Iflag, sizeof(Iflag)) == -1) 894 err(1, "set TCP receive buffer size"); 895 } 896 if (Oflag) { 897 if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, 898 &Oflag, sizeof(Oflag)) == -1) 899 err(1, "set TCP send buffer size"); 900 } 901 if (FreeBSD_Oflag) { 902 if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT, 903 &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1) 904 err(1, "disable TCP options"); 905 } 906 } 907 908 int 909 parse_iptos(char *s) 910 { 911 int tos = -1; 912 913 if (strcmp(s, "lowdelay") == 0) 914 return (IPTOS_LOWDELAY); 915 if (strcmp(s, "throughput") == 0) 916 return (IPTOS_THROUGHPUT); 917 if (strcmp(s, "reliability") == 0) 918 return (IPTOS_RELIABILITY); 919 920 if (sscanf(s, "0x%x", &tos) != 1 || tos < 0 || tos > 0xff) 921 errx(1, "invalid IP Type of Service"); 922 return (tos); 923 } 924 925 void 926 help(void) 927 { 928 usage(0); 929 fprintf(stderr, "\tCommand Summary:\n\ 930 \t-4 Use IPv4\n\ 931 \t-6 Use IPv6\n\ 932 \t-D Enable the debug socket option\n\ 933 \t-d Detach from stdin\n"); 934 #ifdef IPSEC 935 fprintf(stderr, "\ 936 \t-E Use IPsec ESP\n\ 937 \t-e policy Use specified IPsec policy\n"); 938 #endif 939 fprintf(stderr, "\ 940 \t-h This help text\n\ 941 \t-I length TCP receive buffer length\n\ 942 \t-i secs\t Delay interval for lines sent, ports scanned\n\ 943 \t-k Keep inbound sockets open for multiple connects\n\ 944 \t-l Listen mode, for inbound connects\n\ 945 \t-n Suppress name/port resolutions\n\ 946 \t--no-tcpopt Disable TCP options\n\ 947 \t-O length TCP send buffer length\n\ 948 \t-o Terminate on EOF on input\n\ 949 \t-P proxyuser\tUsername for proxy authentication\n\ 950 \t-p port\t Specify local port for remote connects\n\ 951 \t-r Randomize remote ports\n\ 952 \t-S Enable the TCP MD5 signature option\n\ 953 \t-s addr\t Local source address\n\ 954 \t-T ToS\t Set IP Type of Service\n\ 955 \t-t Answer TELNET negotiation\n\ 956 \t-U Use UNIX domain socket\n\ 957 \t-u UDP mode\n\ 958 \t-V fib Specify alternate routing table (FIB)\n\ 959 \t-v Verbose\n\ 960 \t-w secs\t Timeout for connects and final net reads\n\ 961 \t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\ 962 \t-x addr[:port]\tSpecify proxy address and port\n\ 963 \t-z Zero-I/O mode [used for scanning]\n\ 964 Port numbers can be individual or ranges: lo-hi [inclusive]\n"); 965 #ifdef IPSEC 966 fprintf(stderr, "See ipsec_set_policy(3) for -e argument format\n"); 967 #endif 968 exit(1); 969 } 970 971 #ifdef IPSEC 972 void 973 add_ipsec_policy(int s, char *policy) 974 { 975 char *raw; 976 int e; 977 978 raw = ipsec_set_policy(policy, strlen(policy)); 979 if (raw == NULL) 980 errx(1, "ipsec_set_policy `%s': %s", policy, 981 ipsec_strerror()); 982 e = setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, raw, 983 ipsec_get_policylen(raw)); 984 if (e < 0) 985 err(1, "ipsec policy cannot be configured"); 986 free(raw); 987 if (vflag) 988 fprintf(stderr, "ipsec policy configured: `%s'\n", policy); 989 return; 990 } 991 #endif /* IPSEC */ 992 993 void 994 usage(int ret) 995 { 996 fprintf(stderr, 997 #ifdef IPSEC 998 "usage: nc [-46DdEhklnorStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n" 999 #else 1000 "usage: nc [-46DdhklnorStUuvz] [-I length] [-i interval] [-O length]\n" 1001 #endif 1002 "\t [-P proxy_username] [-p source_port] [-s source_ip_address] [-T ToS]\n" 1003 "\t [-V fib] [-w timeout] [-X proxy_protocol]\n" 1004 "\t [-x proxy_address[:port]] [hostname] [port]\n"); 1005 if (ret) 1006 exit(1); 1007 } 1008