1 /* $OpenBSD: netcat.c,v 1.102 2011/09/17 14:10:05 haesbaert Exp $ */ 2 /* 3 * Copyright (c) 2001 Eric Jackson <ericj@monkey.org> 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * Re-written nc(1) for OpenBSD. Original implementation by 31 * *Hobbit* <hobbit@avian.org>. 32 */ 33 34 #include <sys/types.h> 35 #include <sys/socket.h> 36 #include <sys/time.h> 37 #include <sys/un.h> 38 39 #include <netinet/in.h> 40 #include <netinet/in_systm.h> 41 #include <netinet/tcp.h> 42 #include <netinet/ip.h> 43 #include <arpa/telnet.h> 44 45 #include <err.h> 46 #include <errno.h> 47 #include <netdb.h> 48 #include <poll.h> 49 #include <stdarg.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 #include <fcntl.h> 55 #include <limits.h> 56 #include "atomicio.h" 57 58 #ifndef SUN_LEN 59 #define SUN_LEN(su) \ 60 (sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path)) 61 #endif 62 63 #define PORT_MAX 65535 64 #define PORT_MAX_LEN 6 65 #define UNIX_DG_TMP_SOCKET_SIZE 19 66 67 /* Command Line Options */ 68 int dflag; /* detached, no stdin */ 69 unsigned int iflag; /* Interval Flag */ 70 int jflag; /* use jumbo frames if we can */ 71 int kflag; /* More than one connect */ 72 int lflag; /* Bind to local port */ 73 int nflag; /* Don't do name look up */ 74 char *Pflag; /* Proxy username */ 75 char *pflag; /* Localport flag */ 76 int rflag; /* Random ports flag */ 77 char *sflag; /* Source Address */ 78 int tflag; /* Telnet Emulation */ 79 int uflag; /* UDP - Default to TCP */ 80 int vflag; /* Verbosity */ 81 int xflag; /* Socks proxy */ 82 int zflag; /* Port Scan Flag */ 83 int Dflag; /* sodebug */ 84 int Iflag; /* TCP receive buffer size */ 85 int Oflag; /* TCP send buffer size */ 86 int Sflag; /* TCP MD5 signature option */ 87 int Tflag = -1; /* IP Type of Service */ 88 u_int rtableid; 89 90 int timeout = -1; 91 int family = AF_UNSPEC; 92 char *portlist[PORT_MAX+1]; 93 char *unix_dg_tmp_socket; 94 95 void atelnet(int, unsigned char *, unsigned int); 96 void build_ports(char *); 97 void help(void); 98 int local_listen(char *, char *, struct addrinfo); 99 void readwrite(int); 100 int remote_connect(const char *, const char *, struct addrinfo); 101 int socks_connect(const char *, const char *, struct addrinfo, 102 const char *, const char *, struct addrinfo, int, const char *); 103 int udptest(int); 104 int unix_bind(char *); 105 int unix_connect(char *); 106 int unix_listen(char *); 107 void set_common_sockopts(int); 108 int map_tos(char *, int *); 109 void usage(int); 110 111 int 112 main(int argc, char *argv[]) 113 { 114 int ch, s, ret, socksv; 115 char *host, *uport; 116 struct addrinfo hints; 117 struct servent *sv; 118 socklen_t len; 119 struct sockaddr_storage cliaddr; 120 char *proxy; 121 const char *errstr, *proxyhost = "", *proxyport = NULL; 122 struct addrinfo proxyhints; 123 char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE]; 124 125 ret = 1; 126 s = 0; 127 socksv = 5; 128 host = NULL; 129 uport = NULL; 130 sv = NULL; 131 132 while ((ch = getopt(argc, argv, 133 "46DdhI:i:jklnO:P:p:rSs:tT:UuV:vw:X:x:z")) != -1) { 134 switch (ch) { 135 case '4': 136 family = AF_INET; 137 break; 138 case '6': 139 family = AF_INET6; 140 break; 141 case 'U': 142 family = AF_UNIX; 143 break; 144 case 'X': 145 if (strcasecmp(optarg, "connect") == 0) 146 socksv = -1; /* HTTP proxy CONNECT */ 147 else if (strcmp(optarg, "4") == 0) 148 socksv = 4; /* SOCKS v.4 */ 149 else if (strcmp(optarg, "5") == 0) 150 socksv = 5; /* SOCKS v.5 */ 151 else 152 errx(1, "unsupported proxy protocol"); 153 break; 154 case 'd': 155 dflag = 1; 156 break; 157 case 'h': 158 help(); 159 break; 160 case 'i': 161 iflag = strtonum(optarg, 0, UINT_MAX, &errstr); 162 if (errstr) 163 errx(1, "interval %s: %s", errstr, optarg); 164 break; 165 case 'j': 166 jflag = 1; 167 break; 168 case 'k': 169 kflag = 1; 170 break; 171 case 'l': 172 lflag = 1; 173 break; 174 case 'n': 175 nflag = 1; 176 break; 177 case 'P': 178 Pflag = optarg; 179 break; 180 case 'p': 181 pflag = optarg; 182 break; 183 case 'r': 184 rflag = 1; 185 break; 186 case 's': 187 sflag = optarg; 188 break; 189 case 't': 190 tflag = 1; 191 break; 192 case 'u': 193 uflag = 1; 194 break; 195 case 'V': 196 rtableid = (unsigned int)strtonum(optarg, 0, 197 RT_TABLEID_MAX, &errstr); 198 if (errstr) 199 errx(1, "rtable %s: %s", errstr, optarg); 200 break; 201 case 'v': 202 vflag = 1; 203 break; 204 case 'w': 205 timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr); 206 if (errstr) 207 errx(1, "timeout %s: %s", errstr, optarg); 208 timeout *= 1000; 209 break; 210 case 'x': 211 xflag = 1; 212 if ((proxy = strdup(optarg)) == NULL) 213 err(1, NULL); 214 break; 215 case 'z': 216 zflag = 1; 217 break; 218 case 'D': 219 Dflag = 1; 220 break; 221 case 'I': 222 Iflag = strtonum(optarg, 1, 65536 << 14, &errstr); 223 if (errstr != NULL) 224 errx(1, "TCP receive window %s: %s", 225 errstr, optarg); 226 break; 227 case 'O': 228 Oflag = strtonum(optarg, 1, 65536 << 14, &errstr); 229 if (errstr != NULL) 230 errx(1, "TCP send window %s: %s", 231 errstr, optarg); 232 break; 233 case 'S': 234 Sflag = 1; 235 break; 236 case 'T': 237 errstr = NULL; 238 errno = 0; 239 if (map_tos(optarg, &Tflag)) 240 break; 241 if (strlen(optarg) > 1 && optarg[0] == '0' && 242 optarg[1] == 'x') 243 Tflag = (int)strtol(optarg, NULL, 16); 244 else 245 Tflag = (int)strtonum(optarg, 0, 255, 246 &errstr); 247 if (Tflag < 0 || Tflag > 255 || errstr || errno) 248 errx(1, "illegal tos value %s", optarg); 249 break; 250 default: 251 usage(1); 252 } 253 } 254 argc -= optind; 255 argv += optind; 256 257 /* Cruft to make sure options are clean, and used properly. */ 258 if (argv[0] && !argv[1] && family == AF_UNIX) { 259 host = argv[0]; 260 uport = NULL; 261 } else if (argv[0] && !argv[1]) { 262 if (!lflag) 263 usage(1); 264 uport = argv[0]; 265 host = NULL; 266 } else if (argv[0] && argv[1]) { 267 host = argv[0]; 268 uport = argv[1]; 269 } else 270 usage(1); 271 272 if (lflag && sflag) 273 errx(1, "cannot use -s and -l"); 274 if (lflag && pflag) 275 errx(1, "cannot use -p and -l"); 276 if (lflag && zflag) 277 errx(1, "cannot use -z and -l"); 278 if (!lflag && kflag) 279 errx(1, "must use -l with -k"); 280 281 /* Get name of temporary socket for unix datagram client */ 282 if ((family == AF_UNIX) && uflag && !lflag) { 283 if (sflag) { 284 unix_dg_tmp_socket = sflag; 285 } else { 286 strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX", 287 UNIX_DG_TMP_SOCKET_SIZE); 288 if (mktemp(unix_dg_tmp_socket_buf) == NULL) 289 err(1, "mktemp"); 290 unix_dg_tmp_socket = unix_dg_tmp_socket_buf; 291 } 292 } 293 294 /* Initialize addrinfo structure. */ 295 if (family != AF_UNIX) { 296 memset(&hints, 0, sizeof(struct addrinfo)); 297 hints.ai_family = family; 298 hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 299 hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 300 if (nflag) 301 hints.ai_flags |= AI_NUMERICHOST; 302 } 303 304 if (xflag) { 305 if (uflag) 306 errx(1, "no proxy support for UDP mode"); 307 308 if (lflag) 309 errx(1, "no proxy support for listen"); 310 311 if (family == AF_UNIX) 312 errx(1, "no proxy support for unix sockets"); 313 314 /* XXX IPv6 transport to proxy would probably work */ 315 if (family == AF_INET6) 316 errx(1, "no proxy support for IPv6"); 317 318 if (sflag) 319 errx(1, "no proxy support for local source address"); 320 321 proxyhost = strsep(&proxy, ":"); 322 proxyport = proxy; 323 324 memset(&proxyhints, 0, sizeof(struct addrinfo)); 325 proxyhints.ai_family = family; 326 proxyhints.ai_socktype = SOCK_STREAM; 327 proxyhints.ai_protocol = IPPROTO_TCP; 328 if (nflag) 329 proxyhints.ai_flags |= AI_NUMERICHOST; 330 } 331 332 if (lflag) { 333 int connfd; 334 ret = 0; 335 336 if (family == AF_UNIX) { 337 if (uflag) 338 s = unix_bind(host); 339 else 340 s = unix_listen(host); 341 } 342 343 /* Allow only one connection at a time, but stay alive. */ 344 for (;;) { 345 if (family != AF_UNIX) 346 s = local_listen(host, uport, hints); 347 if (s < 0) 348 err(1, NULL); 349 /* 350 * For UDP, we will use recvfrom() initially 351 * to wait for a caller, then use the regular 352 * functions to talk to the caller. 353 */ 354 if (uflag) { 355 int rv, plen; 356 char buf[16384]; 357 struct sockaddr_storage z; 358 359 len = sizeof(z); 360 plen = jflag ? 16384 : 2048; 361 rv = recvfrom(s, buf, plen, MSG_PEEK, 362 (struct sockaddr *)&z, &len); 363 if (rv < 0) 364 err(1, "recvfrom"); 365 366 rv = connect(s, (struct sockaddr *)&z, len); 367 if (rv < 0) 368 err(1, "connect"); 369 370 readwrite(s); 371 } else { 372 len = sizeof(cliaddr); 373 connfd = accept(s, (struct sockaddr *)&cliaddr, 374 &len); 375 readwrite(connfd); 376 close(connfd); 377 } 378 379 if (family != AF_UNIX) 380 close(s); 381 else if (uflag) { 382 if (connect(s, NULL, 0) < 0) 383 err(1, "connect"); 384 } 385 386 if (!kflag) 387 break; 388 } 389 } else if (family == AF_UNIX) { 390 ret = 0; 391 392 if ((s = unix_connect(host)) > 0 && !zflag) { 393 readwrite(s); 394 close(s); 395 } else 396 ret = 1; 397 398 if (uflag) 399 unlink(unix_dg_tmp_socket); 400 exit(ret); 401 402 } else { 403 int i = 0; 404 405 /* Construct the portlist[] array. */ 406 build_ports(uport); 407 408 /* Cycle through portlist, connecting to each port. */ 409 for (i = 0; portlist[i] != NULL; i++) { 410 if (s) 411 close(s); 412 413 if (xflag) 414 s = socks_connect(host, portlist[i], hints, 415 proxyhost, proxyport, proxyhints, socksv, 416 Pflag); 417 else 418 s = remote_connect(host, portlist[i], hints); 419 420 if (s < 0) 421 continue; 422 423 ret = 0; 424 if (vflag || zflag) { 425 /* For UDP, make sure we are connected. */ 426 if (uflag) { 427 if (udptest(s) == -1) { 428 ret = 1; 429 continue; 430 } 431 } 432 433 /* Don't look up port if -n. */ 434 if (nflag) 435 sv = NULL; 436 else { 437 sv = getservbyport( 438 ntohs(atoi(portlist[i])), 439 uflag ? "udp" : "tcp"); 440 } 441 442 fprintf(stderr, 443 "Connection to %s %s port [%s/%s] " 444 "succeeded!\n", host, portlist[i], 445 uflag ? "udp" : "tcp", 446 sv ? sv->s_name : "*"); 447 } 448 if (!zflag) 449 readwrite(s); 450 } 451 } 452 453 if (s) 454 close(s); 455 456 exit(ret); 457 } 458 459 /* 460 * unix_bind() 461 * Returns a unix socket bound to the given path 462 */ 463 int 464 unix_bind(char *path) 465 { 466 struct sockaddr_un sun; 467 int s; 468 469 /* Create unix domain socket. */ 470 if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM, 471 0)) < 0) 472 return (-1); 473 474 memset(&sun, 0, sizeof(struct sockaddr_un)); 475 sun.sun_family = AF_UNIX; 476 477 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 478 sizeof(sun.sun_path)) { 479 close(s); 480 errno = ENAMETOOLONG; 481 return (-1); 482 } 483 484 if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 485 close(s); 486 return (-1); 487 } 488 return (s); 489 } 490 491 /* 492 * unix_connect() 493 * Returns a socket connected to a local unix socket. Returns -1 on failure. 494 */ 495 int 496 unix_connect(char *path) 497 { 498 struct sockaddr_un sun; 499 int s; 500 501 if (uflag) { 502 if ((s = unix_bind(unix_dg_tmp_socket)) < 0) 503 return (-1); 504 } else { 505 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) 506 return (-1); 507 } 508 (void)fcntl(s, F_SETFD, 1); 509 510 memset(&sun, 0, sizeof(struct sockaddr_un)); 511 sun.sun_family = AF_UNIX; 512 513 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >= 514 sizeof(sun.sun_path)) { 515 close(s); 516 errno = ENAMETOOLONG; 517 return (-1); 518 } 519 if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) { 520 close(s); 521 return (-1); 522 } 523 return (s); 524 525 } 526 527 /* 528 * unix_listen() 529 * Create a unix domain socket, and listen on it. 530 */ 531 int 532 unix_listen(char *path) 533 { 534 int s; 535 if ((s = unix_bind(path)) < 0) 536 return (-1); 537 538 if (listen(s, 5) < 0) { 539 close(s); 540 return (-1); 541 } 542 return (s); 543 } 544 545 /* 546 * remote_connect() 547 * Returns a socket connected to a remote host. Properly binds to a local 548 * port or source address if needed. Returns -1 on failure. 549 */ 550 int 551 remote_connect(const char *host, const char *port, struct addrinfo hints) 552 { 553 struct addrinfo *res, *res0; 554 int s, error, on = 1; 555 556 if ((error = getaddrinfo(host, port, &hints, &res))) 557 errx(1, "getaddrinfo: %s", gai_strerror(error)); 558 559 res0 = res; 560 do { 561 if ((s = socket(res0->ai_family, res0->ai_socktype, 562 res0->ai_protocol)) < 0) 563 continue; 564 565 if (rtableid) { 566 if (setsockopt(s, SOL_SOCKET, SO_RTABLE, &rtableid, 567 sizeof(rtableid)) == -1) 568 err(1, "setsockopt SO_RTABLE"); 569 } 570 571 /* Bind to a local port or source address if specified. */ 572 if (sflag || pflag) { 573 struct addrinfo ahints, *ares; 574 575 /* try SO_BINDANY, but don't insist */ 576 setsockopt(s, SOL_SOCKET, SO_BINDANY, &on, sizeof(on)); 577 memset(&ahints, 0, sizeof(struct addrinfo)); 578 ahints.ai_family = res0->ai_family; 579 ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM; 580 ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP; 581 ahints.ai_flags = AI_PASSIVE; 582 if ((error = getaddrinfo(sflag, pflag, &ahints, &ares))) 583 errx(1, "getaddrinfo: %s", gai_strerror(error)); 584 585 if (bind(s, (struct sockaddr *)ares->ai_addr, 586 ares->ai_addrlen) < 0) 587 errx(1, "bind failed: %s", strerror(errno)); 588 freeaddrinfo(ares); 589 } 590 591 set_common_sockopts(s); 592 593 if (connect(s, res0->ai_addr, res0->ai_addrlen) == 0) 594 break; 595 else if (vflag) 596 warn("connect to %s port %s (%s) failed", host, port, 597 uflag ? "udp" : "tcp"); 598 599 close(s); 600 s = -1; 601 } while ((res0 = res0->ai_next) != NULL); 602 603 freeaddrinfo(res); 604 605 return (s); 606 } 607 608 /* 609 * local_listen() 610 * Returns a socket listening on a local port, binds to specified source 611 * address. Returns -1 on failure. 612 */ 613 int 614 local_listen(char *host, char *port, struct addrinfo hints) 615 { 616 struct addrinfo *res, *res0; 617 int s, ret, x = 1; 618 int error; 619 620 /* Allow nodename to be null. */ 621 hints.ai_flags |= AI_PASSIVE; 622 623 /* 624 * In the case of binding to a wildcard address 625 * default to binding to an ipv4 address. 626 */ 627 if (host == NULL && hints.ai_family == AF_UNSPEC) 628 hints.ai_family = AF_INET; 629 630 if ((error = getaddrinfo(host, port, &hints, &res))) 631 errx(1, "getaddrinfo: %s", gai_strerror(error)); 632 633 res0 = res; 634 do { 635 if ((s = socket(res0->ai_family, res0->ai_socktype, 636 res0->ai_protocol)) < 0) 637 continue; 638 639 if (rtableid) { 640 if (setsockopt(s, IPPROTO_IP, SO_RTABLE, &rtableid, 641 sizeof(rtableid)) == -1) 642 err(1, "setsockopt SO_RTABLE"); 643 } 644 645 ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x)); 646 if (ret == -1) 647 err(1, NULL); 648 649 set_common_sockopts(s); 650 651 if (bind(s, (struct sockaddr *)res0->ai_addr, 652 res0->ai_addrlen) == 0) 653 break; 654 655 close(s); 656 s = -1; 657 } while ((res0 = res0->ai_next) != NULL); 658 659 if (!uflag && s != -1) { 660 if (listen(s, 1) < 0) 661 err(1, "listen"); 662 } 663 664 freeaddrinfo(res); 665 666 return (s); 667 } 668 669 /* 670 * readwrite() 671 * Loop that polls on the network file descriptor and stdin. 672 */ 673 void 674 readwrite(int nfd) 675 { 676 struct pollfd pfd[2]; 677 unsigned char buf[16384]; 678 int n, wfd = fileno(stdin); 679 int lfd = fileno(stdout); 680 int plen; 681 682 plen = jflag ? 16384 : 2048; 683 684 /* Setup Network FD */ 685 pfd[0].fd = nfd; 686 pfd[0].events = POLLIN; 687 688 /* Set up STDIN FD. */ 689 pfd[1].fd = wfd; 690 pfd[1].events = POLLIN; 691 692 while (pfd[0].fd != -1) { 693 if (iflag) 694 sleep(iflag); 695 696 if ((n = poll(pfd, 2 - dflag, timeout)) < 0) { 697 close(nfd); 698 err(1, "Polling Error"); 699 } 700 701 if (n == 0) 702 return; 703 704 if (pfd[0].revents & POLLIN) { 705 if ((n = read(nfd, buf, plen)) < 0) 706 return; 707 else if (n == 0) { 708 shutdown(nfd, SHUT_RD); 709 pfd[0].fd = -1; 710 pfd[0].events = 0; 711 } else { 712 if (tflag) 713 atelnet(nfd, buf, n); 714 if (atomicio(vwrite, lfd, buf, n) != n) 715 return; 716 } 717 } 718 719 if (!dflag && pfd[1].revents & POLLIN) { 720 if ((n = read(wfd, buf, plen)) < 0) 721 return; 722 else if (n == 0) { 723 shutdown(nfd, SHUT_WR); 724 pfd[1].fd = -1; 725 pfd[1].events = 0; 726 } else { 727 if (atomicio(vwrite, nfd, buf, n) != n) 728 return; 729 } 730 } 731 } 732 } 733 734 /* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */ 735 void 736 atelnet(int nfd, unsigned char *buf, unsigned int size) 737 { 738 unsigned char *p, *end; 739 unsigned char obuf[4]; 740 741 if (size < 3) 742 return; 743 end = buf + size - 2; 744 745 for (p = buf; p < end; p++) { 746 if (*p != IAC) 747 continue; 748 749 obuf[0] = IAC; 750 p++; 751 if ((*p == WILL) || (*p == WONT)) 752 obuf[1] = DONT; 753 else if ((*p == DO) || (*p == DONT)) 754 obuf[1] = WONT; 755 else 756 continue; 757 758 p++; 759 obuf[2] = *p; 760 if (atomicio(vwrite, nfd, obuf, 3) != 3) 761 warn("Write Error!"); 762 } 763 } 764 765 /* 766 * build_ports() 767 * Build an array or ports in portlist[], listing each port 768 * that we should try to connect to. 769 */ 770 void 771 build_ports(char *p) 772 { 773 const char *errstr; 774 char *n; 775 int hi, lo, cp; 776 int x = 0; 777 778 if ((n = strchr(p, '-')) != NULL) { 779 if (lflag) 780 errx(1, "Cannot use -l with multiple ports!"); 781 782 *n = '\0'; 783 n++; 784 785 /* Make sure the ports are in order: lowest->highest. */ 786 hi = strtonum(n, 1, PORT_MAX, &errstr); 787 if (errstr) 788 errx(1, "port number %s: %s", errstr, n); 789 lo = strtonum(p, 1, PORT_MAX, &errstr); 790 if (errstr) 791 errx(1, "port number %s: %s", errstr, p); 792 793 if (lo > hi) { 794 cp = hi; 795 hi = lo; 796 lo = cp; 797 } 798 799 /* Load ports sequentially. */ 800 for (cp = lo; cp <= hi; cp++) { 801 portlist[x] = calloc(1, PORT_MAX_LEN); 802 if (portlist[x] == NULL) 803 err(1, NULL); 804 snprintf(portlist[x], PORT_MAX_LEN, "%d", cp); 805 x++; 806 } 807 808 /* Randomly swap ports. */ 809 if (rflag) { 810 int y; 811 char *c; 812 813 for (x = 0; x <= (hi - lo); x++) { 814 y = (arc4random() & 0xFFFF) % (hi - lo); 815 c = portlist[x]; 816 portlist[x] = portlist[y]; 817 portlist[y] = c; 818 } 819 } 820 } else { 821 hi = strtonum(p, 1, PORT_MAX, &errstr); 822 if (errstr) 823 errx(1, "port number %s: %s", errstr, p); 824 portlist[0] = strdup(p); 825 if (portlist[0] == NULL) 826 err(1, NULL); 827 } 828 } 829 830 /* 831 * udptest() 832 * Do a few writes to see if the UDP port is there. 833 * XXX - Better way of doing this? Doesn't work for IPv6. 834 * Also fails after around 100 ports checked. 835 */ 836 int 837 udptest(int s) 838 { 839 int i, ret; 840 841 for (i = 0; i <= 3; i++) { 842 if (write(s, "X", 1) == 1) 843 ret = 1; 844 else 845 ret = -1; 846 } 847 return (ret); 848 } 849 850 void 851 set_common_sockopts(int s) 852 { 853 int x = 1; 854 855 if (Sflag) { 856 if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG, 857 &x, sizeof(x)) == -1) 858 err(1, NULL); 859 } 860 if (Dflag) { 861 if (setsockopt(s, SOL_SOCKET, SO_DEBUG, 862 &x, sizeof(x)) == -1) 863 err(1, NULL); 864 } 865 if (jflag) { 866 if (setsockopt(s, SOL_SOCKET, SO_JUMBO, 867 &x, sizeof(x)) == -1) 868 err(1, NULL); 869 } 870 if (Tflag != -1) { 871 if (setsockopt(s, IPPROTO_IP, IP_TOS, 872 &Tflag, sizeof(Tflag)) == -1) 873 err(1, "set IP ToS"); 874 } 875 if (Iflag) { 876 if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, 877 &Iflag, sizeof(Iflag)) == -1) 878 err(1, "set TCP receive buffer size"); 879 } 880 if (Oflag) { 881 if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, 882 &Oflag, sizeof(Oflag)) == -1) 883 err(1, "set TCP send buffer size"); 884 } 885 } 886 887 int 888 map_tos(char *s, int *val) 889 { 890 /* DiffServ Codepoints and other TOS mappings */ 891 const struct toskeywords { 892 const char *keyword; 893 int val; 894 } *t, toskeywords[] = { 895 { "af11", IPTOS_DSCP_AF11 }, 896 { "af12", IPTOS_DSCP_AF12 }, 897 { "af13", IPTOS_DSCP_AF13 }, 898 { "af21", IPTOS_DSCP_AF21 }, 899 { "af22", IPTOS_DSCP_AF22 }, 900 { "af23", IPTOS_DSCP_AF23 }, 901 { "af31", IPTOS_DSCP_AF31 }, 902 { "af32", IPTOS_DSCP_AF32 }, 903 { "af33", IPTOS_DSCP_AF33 }, 904 { "af41", IPTOS_DSCP_AF41 }, 905 { "af42", IPTOS_DSCP_AF42 }, 906 { "af43", IPTOS_DSCP_AF43 }, 907 { "critical", IPTOS_PREC_CRITIC_ECP }, 908 { "cs0", IPTOS_DSCP_CS0 }, 909 { "cs1", IPTOS_DSCP_CS1 }, 910 { "cs2", IPTOS_DSCP_CS2 }, 911 { "cs3", IPTOS_DSCP_CS3 }, 912 { "cs4", IPTOS_DSCP_CS4 }, 913 { "cs5", IPTOS_DSCP_CS5 }, 914 { "cs6", IPTOS_DSCP_CS6 }, 915 { "cs7", IPTOS_DSCP_CS7 }, 916 { "ef", IPTOS_DSCP_EF }, 917 { "inetcontrol", IPTOS_PREC_INTERNETCONTROL }, 918 { "lowdelay", IPTOS_LOWDELAY }, 919 { "netcontrol", IPTOS_PREC_NETCONTROL }, 920 { "reliability", IPTOS_RELIABILITY }, 921 { "throughput", IPTOS_THROUGHPUT }, 922 { NULL, -1 }, 923 }; 924 925 for (t = toskeywords; t->keyword != NULL; t++) { 926 if (strcmp(s, t->keyword) == 0) { 927 *val = t->val; 928 return (1); 929 } 930 } 931 932 return (0); 933 } 934 935 void 936 help(void) 937 { 938 usage(0); 939 fprintf(stderr, "\tCommand Summary:\n\ 940 \t-4 Use IPv4\n\ 941 \t-6 Use IPv6\n\ 942 \t-D Enable the debug socket option\n\ 943 \t-d Detach from stdin\n\ 944 \t-h This help text\n\ 945 \t-I length TCP receive buffer length\n\ 946 \t-i secs\t Delay interval for lines sent, ports scanned\n\ 947 \t-k Keep inbound sockets open for multiple connects\n\ 948 \t-l Listen mode, for inbound connects\n\ 949 \t-n Suppress name/port resolutions\n\ 950 \t-O length TCP send buffer length\n\ 951 \t-P proxyuser\tUsername for proxy authentication\n\ 952 \t-p port\t Specify local port for remote connects\n\ 953 \t-r Randomize remote ports\n\ 954 \t-S Enable the TCP MD5 signature option\n\ 955 \t-s addr\t Local source address\n\ 956 \t-T toskeyword\tSet IP Type of Service\n\ 957 \t-t Answer TELNET negotiation\n\ 958 \t-U Use UNIX domain socket\n\ 959 \t-u UDP mode\n\ 960 \t-V rtable Specify alternate routing table\n\ 961 \t-v Verbose\n\ 962 \t-w secs\t Timeout for connects and final net reads\n\ 963 \t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\ 964 \t-x addr[:port]\tSpecify proxy address and port\n\ 965 \t-z Zero-I/O mode [used for scanning]\n\ 966 Port numbers can be individual or ranges: lo-hi [inclusive]\n"); 967 exit(1); 968 } 969 970 void 971 usage(int ret) 972 { 973 fprintf(stderr, 974 "usage: nc [-46DdhklnrStUuvz] [-I length] [-i interval] [-O length]\n" 975 "\t [-P proxy_username] [-p source_port] [-s source] [-T ToS]\n" 976 "\t [-V rtable] [-w timeout] [-X proxy_protocol]\n" 977 "\t [-x proxy_address[:port]] [destination] [port]\n"); 978 if (ret) 979 exit(1); 980 } 981