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-rw-r--r--src/usr.bin/nc/netcat.c1047
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diff --git a/src/usr.bin/nc/netcat.c b/src/usr.bin/nc/netcat.c
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--- a/src/usr.bin/nc/netcat.c
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1/* $OpenBSD: netcat.c,v 1.109 2012/07/07 15:33:02 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 */
68int dflag; /* detached, no stdin */
69unsigned int iflag; /* Interval Flag */
70int kflag; /* More than one connect */
71int lflag; /* Bind to local port */
72int nflag; /* Don't do name look up */
73char *Pflag; /* Proxy username */
74char *pflag; /* Localport flag */
75int rflag; /* Random ports flag */
76char *sflag; /* Source Address */
77int tflag; /* Telnet Emulation */
78int uflag; /* UDP - Default to TCP */
79int vflag; /* Verbosity */
80int xflag; /* Socks proxy */
81int zflag; /* Port Scan Flag */
82int Dflag; /* sodebug */
83int Iflag; /* TCP receive buffer size */
84int Oflag; /* TCP send buffer size */
85int Sflag; /* TCP MD5 signature option */
86int Tflag = -1; /* IP Type of Service */
87u_int rtableid;
88
89int timeout = -1;
90int family = AF_UNSPEC;
91char *portlist[PORT_MAX+1];
92char *unix_dg_tmp_socket;
93
94void atelnet(int, unsigned char *, unsigned int);
95void build_ports(char *);
96void help(void);
97int local_listen(char *, char *, struct addrinfo);
98void readwrite(int);
99int remote_connect(const char *, const char *, struct addrinfo);
100int timeout_connect(int, const struct sockaddr *, socklen_t);
101int socks_connect(const char *, const char *, struct addrinfo,
102 const char *, const char *, struct addrinfo, int, const char *);
103int udptest(int);
104int unix_bind(char *);
105int unix_connect(char *);
106int unix_listen(char *);
107void set_common_sockopts(int);
108int map_tos(char *, int *);
109void report_connect(const struct sockaddr *, socklen_t);
110void usage(int);
111
112int
113main(int argc, char *argv[])
114{
115 int ch, s, ret, socksv;
116 char *host, *uport;
117 struct addrinfo hints;
118 struct servent *sv;
119 socklen_t len;
120 struct sockaddr_storage cliaddr;
121 char *proxy;
122 const char *errstr, *proxyhost = "", *proxyport = NULL;
123 struct addrinfo proxyhints;
124 char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE];
125
126 ret = 1;
127 s = 0;
128 socksv = 5;
129 host = NULL;
130 uport = NULL;
131 sv = NULL;
132
133 while ((ch = getopt(argc, argv,
134 "46DdhI:i:klnO:P:p:rSs:tT:UuV:vw:X:x:z")) != -1) {
135 switch (ch) {
136 case '4':
137 family = AF_INET;
138 break;
139 case '6':
140 family = AF_INET6;
141 break;
142 case 'U':
143 family = AF_UNIX;
144 break;
145 case 'X':
146 if (strcasecmp(optarg, "connect") == 0)
147 socksv = -1; /* HTTP proxy CONNECT */
148 else if (strcmp(optarg, "4") == 0)
149 socksv = 4; /* SOCKS v.4 */
150 else if (strcmp(optarg, "5") == 0)
151 socksv = 5; /* SOCKS v.5 */
152 else
153 errx(1, "unsupported proxy protocol");
154 break;
155 case 'd':
156 dflag = 1;
157 break;
158 case 'h':
159 help();
160 break;
161 case 'i':
162 iflag = strtonum(optarg, 0, UINT_MAX, &errstr);
163 if (errstr)
164 errx(1, "interval %s: %s", errstr, optarg);
165 break;
166 case 'k':
167 kflag = 1;
168 break;
169 case 'l':
170 lflag = 1;
171 break;
172 case 'n':
173 nflag = 1;
174 break;
175 case 'P':
176 Pflag = optarg;
177 break;
178 case 'p':
179 pflag = optarg;
180 break;
181 case 'r':
182 rflag = 1;
183 break;
184 case 's':
185 sflag = optarg;
186 break;
187 case 't':
188 tflag = 1;
189 break;
190 case 'u':
191 uflag = 1;
192 break;
193 case 'V':
194 rtableid = (unsigned int)strtonum(optarg, 0,
195 RT_TABLEID_MAX, &errstr);
196 if (errstr)
197 errx(1, "rtable %s: %s", errstr, optarg);
198 break;
199 case 'v':
200 vflag = 1;
201 break;
202 case 'w':
203 timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr);
204 if (errstr)
205 errx(1, "timeout %s: %s", errstr, optarg);
206 timeout *= 1000;
207 break;
208 case 'x':
209 xflag = 1;
210 if ((proxy = strdup(optarg)) == NULL)
211 err(1, NULL);
212 break;
213 case 'z':
214 zflag = 1;
215 break;
216 case 'D':
217 Dflag = 1;
218 break;
219 case 'I':
220 Iflag = strtonum(optarg, 1, 65536 << 14, &errstr);
221 if (errstr != NULL)
222 errx(1, "TCP receive window %s: %s",
223 errstr, optarg);
224 break;
225 case 'O':
226 Oflag = strtonum(optarg, 1, 65536 << 14, &errstr);
227 if (errstr != NULL)
228 errx(1, "TCP send window %s: %s",
229 errstr, optarg);
230 break;
231 case 'S':
232 Sflag = 1;
233 break;
234 case 'T':
235 errstr = NULL;
236 errno = 0;
237 if (map_tos(optarg, &Tflag))
238 break;
239 if (strlen(optarg) > 1 && optarg[0] == '0' &&
240 optarg[1] == 'x')
241 Tflag = (int)strtol(optarg, NULL, 16);
242 else
243 Tflag = (int)strtonum(optarg, 0, 255,
244 &errstr);
245 if (Tflag < 0 || Tflag > 255 || errstr || errno)
246 errx(1, "illegal tos value %s", optarg);
247 break;
248 default:
249 usage(1);
250 }
251 }
252 argc -= optind;
253 argv += optind;
254
255 /* Cruft to make sure options are clean, and used properly. */
256 if (argv[0] && !argv[1] && family == AF_UNIX) {
257 host = argv[0];
258 uport = NULL;
259 } else if (argv[0] && !argv[1]) {
260 if (!lflag)
261 usage(1);
262 uport = argv[0];
263 host = NULL;
264 } else if (argv[0] && argv[1]) {
265 host = argv[0];
266 uport = argv[1];
267 } else
268 usage(1);
269
270 if (lflag && sflag)
271 errx(1, "cannot use -s and -l");
272 if (lflag && pflag)
273 errx(1, "cannot use -p and -l");
274 if (lflag && zflag)
275 errx(1, "cannot use -z and -l");
276 if (!lflag && kflag)
277 errx(1, "must use -l with -k");
278
279 /* Get name of temporary socket for unix datagram client */
280 if ((family == AF_UNIX) && uflag && !lflag) {
281 if (sflag) {
282 unix_dg_tmp_socket = sflag;
283 } else {
284 strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX",
285 UNIX_DG_TMP_SOCKET_SIZE);
286 if (mktemp(unix_dg_tmp_socket_buf) == NULL)
287 err(1, "mktemp");
288 unix_dg_tmp_socket = unix_dg_tmp_socket_buf;
289 }
290 }
291
292 /* Initialize addrinfo structure. */
293 if (family != AF_UNIX) {
294 memset(&hints, 0, sizeof(struct addrinfo));
295 hints.ai_family = family;
296 hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM;
297 hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP;
298 if (nflag)
299 hints.ai_flags |= AI_NUMERICHOST;
300 }
301
302 if (xflag) {
303 if (uflag)
304 errx(1, "no proxy support for UDP mode");
305
306 if (lflag)
307 errx(1, "no proxy support for listen");
308
309 if (family == AF_UNIX)
310 errx(1, "no proxy support for unix sockets");
311
312 /* XXX IPv6 transport to proxy would probably work */
313 if (family == AF_INET6)
314 errx(1, "no proxy support for IPv6");
315
316 if (sflag)
317 errx(1, "no proxy support for local source address");
318
319 proxyhost = strsep(&proxy, ":");
320 proxyport = proxy;
321
322 memset(&proxyhints, 0, sizeof(struct addrinfo));
323 proxyhints.ai_family = family;
324 proxyhints.ai_socktype = SOCK_STREAM;
325 proxyhints.ai_protocol = IPPROTO_TCP;
326 if (nflag)
327 proxyhints.ai_flags |= AI_NUMERICHOST;
328 }
329
330 if (lflag) {
331 int connfd;
332 ret = 0;
333
334 if (family == AF_UNIX) {
335 if (uflag)
336 s = unix_bind(host);
337 else
338 s = unix_listen(host);
339 }
340
341 /* Allow only one connection at a time, but stay alive. */
342 for (;;) {
343 if (family != AF_UNIX)
344 s = local_listen(host, uport, hints);
345 if (s < 0)
346 err(1, NULL);
347 /*
348 * For UDP and -k, don't connect the socket, let it
349 * receive datagrams from multiple socket pairs.
350 */
351 if (uflag && kflag)
352 readwrite(s);
353 /*
354 * For UDP and not -k, we will use recvfrom() initially
355 * to wait for a caller, then use the regular functions
356 * to talk to the caller.
357 */
358 else if (uflag && !kflag) {
359 int rv, plen;
360 char buf[16384];
361 struct sockaddr_storage z;
362
363 len = sizeof(z);
364 plen = 2048;
365 rv = recvfrom(s, buf, plen, MSG_PEEK,
366 (struct sockaddr *)&z, &len);
367 if (rv < 0)
368 err(1, "recvfrom");
369
370 rv = connect(s, (struct sockaddr *)&z, len);
371 if (rv < 0)
372 err(1, "connect");
373
374 if (vflag)
375 report_connect((struct sockaddr *)&z, len);
376
377 readwrite(s);
378 } else {
379 len = sizeof(cliaddr);
380 connfd = accept(s, (struct sockaddr *)&cliaddr,
381 &len);
382 if (connfd == -1)
383 err(1, "accept");
384
385 if (vflag)
386 report_connect((struct sockaddr *)&cliaddr, len);
387
388 readwrite(connfd);
389 close(connfd);
390 }
391
392 if (family != AF_UNIX)
393 close(s);
394 else if (uflag) {
395 if (connect(s, NULL, 0) < 0)
396 err(1, "connect");
397 }
398
399 if (!kflag)
400 break;
401 }
402 } else if (family == AF_UNIX) {
403 ret = 0;
404
405 if ((s = unix_connect(host)) > 0 && !zflag) {
406 readwrite(s);
407 close(s);
408 } else
409 ret = 1;
410
411 if (uflag)
412 unlink(unix_dg_tmp_socket);
413 exit(ret);
414
415 } else {
416 int i = 0;
417
418 /* Construct the portlist[] array. */
419 build_ports(uport);
420
421 /* Cycle through portlist, connecting to each port. */
422 for (i = 0; portlist[i] != NULL; i++) {
423 if (s)
424 close(s);
425
426 if (xflag)
427 s = socks_connect(host, portlist[i], hints,
428 proxyhost, proxyport, proxyhints, socksv,
429 Pflag);
430 else
431 s = remote_connect(host, portlist[i], hints);
432
433 if (s < 0)
434 continue;
435
436 ret = 0;
437 if (vflag || zflag) {
438 /* For UDP, make sure we are connected. */
439 if (uflag) {
440 if (udptest(s) == -1) {
441 ret = 1;
442 continue;
443 }
444 }
445
446 /* Don't look up port if -n. */
447 if (nflag)
448 sv = NULL;
449 else {
450 sv = getservbyport(
451 ntohs(atoi(portlist[i])),
452 uflag ? "udp" : "tcp");
453 }
454
455 fprintf(stderr,
456 "Connection to %s %s port [%s/%s] "
457 "succeeded!\n", host, portlist[i],
458 uflag ? "udp" : "tcp",
459 sv ? sv->s_name : "*");
460 }
461 if (!zflag)
462 readwrite(s);
463 }
464 }
465
466 if (s)
467 close(s);
468
469 exit(ret);
470}
471
472/*
473 * unix_bind()
474 * Returns a unix socket bound to the given path
475 */
476int
477unix_bind(char *path)
478{
479 struct sockaddr_un sun;
480 int s;
481
482 /* Create unix domain socket. */
483 if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM,
484 0)) < 0)
485 return (-1);
486
487 memset(&sun, 0, sizeof(struct sockaddr_un));
488 sun.sun_family = AF_UNIX;
489
490 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >=
491 sizeof(sun.sun_path)) {
492 close(s);
493 errno = ENAMETOOLONG;
494 return (-1);
495 }
496
497 if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
498 close(s);
499 return (-1);
500 }
501 return (s);
502}
503
504/*
505 * unix_connect()
506 * Returns a socket connected to a local unix socket. Returns -1 on failure.
507 */
508int
509unix_connect(char *path)
510{
511 struct sockaddr_un sun;
512 int s;
513
514 if (uflag) {
515 if ((s = unix_bind(unix_dg_tmp_socket)) < 0)
516 return (-1);
517 } else {
518 if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
519 return (-1);
520 }
521 (void)fcntl(s, F_SETFD, 1);
522
523 memset(&sun, 0, sizeof(struct sockaddr_un));
524 sun.sun_family = AF_UNIX;
525
526 if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >=
527 sizeof(sun.sun_path)) {
528 close(s);
529 errno = ENAMETOOLONG;
530 return (-1);
531 }
532 if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
533 close(s);
534 return (-1);
535 }
536 return (s);
537
538}
539
540/*
541 * unix_listen()
542 * Create a unix domain socket, and listen on it.
543 */
544int
545unix_listen(char *path)
546{
547 int s;
548 if ((s = unix_bind(path)) < 0)
549 return (-1);
550
551 if (listen(s, 5) < 0) {
552 close(s);
553 return (-1);
554 }
555 return (s);
556}
557
558/*
559 * remote_connect()
560 * Returns a socket connected to a remote host. Properly binds to a local
561 * port or source address if needed. Returns -1 on failure.
562 */
563int
564remote_connect(const char *host, const char *port, struct addrinfo hints)
565{
566 struct addrinfo *res, *res0;
567 int s, error, on = 1;
568
569 if ((error = getaddrinfo(host, port, &hints, &res)))
570 errx(1, "getaddrinfo: %s", gai_strerror(error));
571
572 res0 = res;
573 do {
574 if ((s = socket(res0->ai_family, res0->ai_socktype,
575 res0->ai_protocol)) < 0)
576 continue;
577
578 if (rtableid) {
579 if (setsockopt(s, SOL_SOCKET, SO_RTABLE, &rtableid,
580 sizeof(rtableid)) == -1)
581 err(1, "setsockopt SO_RTABLE");
582 }
583
584 /* Bind to a local port or source address if specified. */
585 if (sflag || pflag) {
586 struct addrinfo ahints, *ares;
587
588 /* try SO_BINDANY, but don't insist */
589 setsockopt(s, SOL_SOCKET, SO_BINDANY, &on, sizeof(on));
590 memset(&ahints, 0, sizeof(struct addrinfo));
591 ahints.ai_family = res0->ai_family;
592 ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM;
593 ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP;
594 ahints.ai_flags = AI_PASSIVE;
595 if ((error = getaddrinfo(sflag, pflag, &ahints, &ares)))
596 errx(1, "getaddrinfo: %s", gai_strerror(error));
597
598 if (bind(s, (struct sockaddr *)ares->ai_addr,
599 ares->ai_addrlen) < 0)
600 errx(1, "bind failed: %s", strerror(errno));
601 freeaddrinfo(ares);
602 }
603
604 set_common_sockopts(s);
605
606 if (timeout_connect(s, res0->ai_addr, res0->ai_addrlen) == 0)
607 break;
608 else if (vflag)
609 warn("connect to %s port %s (%s) failed", host, port,
610 uflag ? "udp" : "tcp");
611
612 close(s);
613 s = -1;
614 } while ((res0 = res0->ai_next) != NULL);
615
616 freeaddrinfo(res);
617
618 return (s);
619}
620
621int
622timeout_connect(int s, const struct sockaddr *name, socklen_t namelen)
623{
624 struct pollfd pfd;
625 socklen_t optlen;
626 int flags, optval;
627 int ret;
628
629 if (timeout != -1) {
630 flags = fcntl(s, F_GETFL, 0);
631 if (fcntl(s, F_SETFL, flags | O_NONBLOCK) == -1)
632 err(1, "set non-blocking mode");
633 }
634
635 if ((ret = connect(s, name, namelen)) != 0 && errno == EINPROGRESS) {
636 pfd.fd = s;
637 pfd.events = POLLOUT;
638 if ((ret = poll(&pfd, 1, timeout)) == 1) {
639 optlen = sizeof(optval);
640 if ((ret = getsockopt(s, SOL_SOCKET, SO_ERROR,
641 &optval, &optlen)) == 0) {
642 errno = optval;
643 ret = optval == 0 ? 0 : -1;
644 }
645 } else if (ret == 0) {
646 errno = ETIMEDOUT;
647 ret = -1;
648 } else
649 err(1, "poll failed");
650 }
651
652 if (timeout != -1 && fcntl(s, F_SETFL, flags) == -1)
653 err(1, "restoring flags");
654
655 return (ret);
656}
657
658/*
659 * local_listen()
660 * Returns a socket listening on a local port, binds to specified source
661 * address. Returns -1 on failure.
662 */
663int
664local_listen(char *host, char *port, struct addrinfo hints)
665{
666 struct addrinfo *res, *res0;
667 int s, ret, x = 1;
668 int error;
669
670 /* Allow nodename to be null. */
671 hints.ai_flags |= AI_PASSIVE;
672
673 /*
674 * In the case of binding to a wildcard address
675 * default to binding to an ipv4 address.
676 */
677 if (host == NULL && hints.ai_family == AF_UNSPEC)
678 hints.ai_family = AF_INET;
679
680 if ((error = getaddrinfo(host, port, &hints, &res)))
681 errx(1, "getaddrinfo: %s", gai_strerror(error));
682
683 res0 = res;
684 do {
685 if ((s = socket(res0->ai_family, res0->ai_socktype,
686 res0->ai_protocol)) < 0)
687 continue;
688
689 if (rtableid) {
690 if (setsockopt(s, IPPROTO_IP, SO_RTABLE, &rtableid,
691 sizeof(rtableid)) == -1)
692 err(1, "setsockopt SO_RTABLE");
693 }
694
695 ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x));
696 if (ret == -1)
697 err(1, NULL);
698
699 set_common_sockopts(s);
700
701 if (bind(s, (struct sockaddr *)res0->ai_addr,
702 res0->ai_addrlen) == 0)
703 break;
704
705 close(s);
706 s = -1;
707 } while ((res0 = res0->ai_next) != NULL);
708
709 if (!uflag && s != -1) {
710 if (listen(s, 1) < 0)
711 err(1, "listen");
712 }
713
714 freeaddrinfo(res);
715
716 return (s);
717}
718
719/*
720 * readwrite()
721 * Loop that polls on the network file descriptor and stdin.
722 */
723void
724readwrite(int nfd)
725{
726 struct pollfd pfd[2];
727 unsigned char buf[16384];
728 int n, wfd = fileno(stdin);
729 int lfd = fileno(stdout);
730 int plen;
731
732 plen = 2048;
733
734 /* Setup Network FD */
735 pfd[0].fd = nfd;
736 pfd[0].events = POLLIN;
737
738 /* Set up STDIN FD. */
739 pfd[1].fd = wfd;
740 pfd[1].events = POLLIN;
741
742 while (pfd[0].fd != -1) {
743 if (iflag)
744 sleep(iflag);
745
746 if ((n = poll(pfd, 2 - dflag, timeout)) < 0) {
747 close(nfd);
748 err(1, "Polling Error");
749 }
750
751 if (n == 0)
752 return;
753
754 if (pfd[0].revents & POLLIN) {
755 if ((n = read(nfd, buf, plen)) < 0)
756 return;
757 else if (n == 0) {
758 shutdown(nfd, SHUT_RD);
759 pfd[0].fd = -1;
760 pfd[0].events = 0;
761 } else {
762 if (tflag)
763 atelnet(nfd, buf, n);
764 if (atomicio(vwrite, lfd, buf, n) != n)
765 return;
766 }
767 }
768
769 if (!dflag && pfd[1].revents & POLLIN) {
770 if ((n = read(wfd, buf, plen)) < 0)
771 return;
772 else if (n == 0) {
773 shutdown(nfd, SHUT_WR);
774 pfd[1].fd = -1;
775 pfd[1].events = 0;
776 } else {
777 if (atomicio(vwrite, nfd, buf, n) != n)
778 return;
779 }
780 }
781 }
782}
783
784/* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */
785void
786atelnet(int nfd, unsigned char *buf, unsigned int size)
787{
788 unsigned char *p, *end;
789 unsigned char obuf[4];
790
791 if (size < 3)
792 return;
793 end = buf + size - 2;
794
795 for (p = buf; p < end; p++) {
796 if (*p != IAC)
797 continue;
798
799 obuf[0] = IAC;
800 p++;
801 if ((*p == WILL) || (*p == WONT))
802 obuf[1] = DONT;
803 else if ((*p == DO) || (*p == DONT))
804 obuf[1] = WONT;
805 else
806 continue;
807
808 p++;
809 obuf[2] = *p;
810 if (atomicio(vwrite, nfd, obuf, 3) != 3)
811 warn("Write Error!");
812 }
813}
814
815/*
816 * build_ports()
817 * Build an array of ports in portlist[], listing each port
818 * that we should try to connect to.
819 */
820void
821build_ports(char *p)
822{
823 const char *errstr;
824 char *n;
825 int hi, lo, cp;
826 int x = 0;
827
828 if ((n = strchr(p, '-')) != NULL) {
829 *n = '\0';
830 n++;
831
832 /* Make sure the ports are in order: lowest->highest. */
833 hi = strtonum(n, 1, PORT_MAX, &errstr);
834 if (errstr)
835 errx(1, "port number %s: %s", errstr, n);
836 lo = strtonum(p, 1, PORT_MAX, &errstr);
837 if (errstr)
838 errx(1, "port number %s: %s", errstr, p);
839
840 if (lo > hi) {
841 cp = hi;
842 hi = lo;
843 lo = cp;
844 }
845
846 /* Load ports sequentially. */
847 for (cp = lo; cp <= hi; cp++) {
848 portlist[x] = calloc(1, PORT_MAX_LEN);
849 if (portlist[x] == NULL)
850 err(1, NULL);
851 snprintf(portlist[x], PORT_MAX_LEN, "%d", cp);
852 x++;
853 }
854
855 /* Randomly swap ports. */
856 if (rflag) {
857 int y;
858 char *c;
859
860 for (x = 0; x <= (hi - lo); x++) {
861 y = (arc4random() & 0xFFFF) % (hi - lo);
862 c = portlist[x];
863 portlist[x] = portlist[y];
864 portlist[y] = c;
865 }
866 }
867 } else {
868 hi = strtonum(p, 1, PORT_MAX, &errstr);
869 if (errstr)
870 errx(1, "port number %s: %s", errstr, p);
871 portlist[0] = strdup(p);
872 if (portlist[0] == NULL)
873 err(1, NULL);
874 }
875}
876
877/*
878 * udptest()
879 * Do a few writes to see if the UDP port is there.
880 * Fails once PF state table is full.
881 */
882int
883udptest(int s)
884{
885 int i, ret;
886
887 for (i = 0; i <= 3; i++) {
888 if (write(s, "X", 1) == 1)
889 ret = 1;
890 else
891 ret = -1;
892 }
893 return (ret);
894}
895
896void
897set_common_sockopts(int s)
898{
899 int x = 1;
900
901 if (Sflag) {
902 if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG,
903 &x, sizeof(x)) == -1)
904 err(1, NULL);
905 }
906 if (Dflag) {
907 if (setsockopt(s, SOL_SOCKET, SO_DEBUG,
908 &x, sizeof(x)) == -1)
909 err(1, NULL);
910 }
911 if (Tflag != -1) {
912 if (setsockopt(s, IPPROTO_IP, IP_TOS,
913 &Tflag, sizeof(Tflag)) == -1)
914 err(1, "set IP ToS");
915 }
916 if (Iflag) {
917 if (setsockopt(s, SOL_SOCKET, SO_RCVBUF,
918 &Iflag, sizeof(Iflag)) == -1)
919 err(1, "set TCP receive buffer size");
920 }
921 if (Oflag) {
922 if (setsockopt(s, SOL_SOCKET, SO_SNDBUF,
923 &Oflag, sizeof(Oflag)) == -1)
924 err(1, "set TCP send buffer size");
925 }
926}
927
928int
929map_tos(char *s, int *val)
930{
931 /* DiffServ Codepoints and other TOS mappings */
932 const struct toskeywords {
933 const char *keyword;
934 int val;
935 } *t, toskeywords[] = {
936 { "af11", IPTOS_DSCP_AF11 },
937 { "af12", IPTOS_DSCP_AF12 },
938 { "af13", IPTOS_DSCP_AF13 },
939 { "af21", IPTOS_DSCP_AF21 },
940 { "af22", IPTOS_DSCP_AF22 },
941 { "af23", IPTOS_DSCP_AF23 },
942 { "af31", IPTOS_DSCP_AF31 },
943 { "af32", IPTOS_DSCP_AF32 },
944 { "af33", IPTOS_DSCP_AF33 },
945 { "af41", IPTOS_DSCP_AF41 },
946 { "af42", IPTOS_DSCP_AF42 },
947 { "af43", IPTOS_DSCP_AF43 },
948 { "critical", IPTOS_PREC_CRITIC_ECP },
949 { "cs0", IPTOS_DSCP_CS0 },
950 { "cs1", IPTOS_DSCP_CS1 },
951 { "cs2", IPTOS_DSCP_CS2 },
952 { "cs3", IPTOS_DSCP_CS3 },
953 { "cs4", IPTOS_DSCP_CS4 },
954 { "cs5", IPTOS_DSCP_CS5 },
955 { "cs6", IPTOS_DSCP_CS6 },
956 { "cs7", IPTOS_DSCP_CS7 },
957 { "ef", IPTOS_DSCP_EF },
958 { "inetcontrol", IPTOS_PREC_INTERNETCONTROL },
959 { "lowdelay", IPTOS_LOWDELAY },
960 { "netcontrol", IPTOS_PREC_NETCONTROL },
961 { "reliability", IPTOS_RELIABILITY },
962 { "throughput", IPTOS_THROUGHPUT },
963 { NULL, -1 },
964 };
965
966 for (t = toskeywords; t->keyword != NULL; t++) {
967 if (strcmp(s, t->keyword) == 0) {
968 *val = t->val;
969 return (1);
970 }
971 }
972
973 return (0);
974}
975
976void
977report_connect(const struct sockaddr *sa, socklen_t salen)
978{
979 char remote_host[NI_MAXHOST];
980 char remote_port[NI_MAXSERV];
981 int herr;
982 int flags = NI_NUMERICSERV;
983
984 if (nflag)
985 flags |= NI_NUMERICHOST;
986
987 if ((herr = getnameinfo(sa, salen,
988 remote_host, sizeof(remote_host),
989 remote_port, sizeof(remote_port),
990 flags)) != 0) {
991 if (herr == EAI_SYSTEM)
992 err(1, "getnameinfo");
993 else
994 errx(1, "getnameinfo: %s", gai_strerror(herr));
995 }
996
997 fprintf(stderr,
998 "Connection from %s %s "
999 "received!\n", remote_host, remote_port);
1000}
1001
1002void
1003help(void)
1004{
1005 usage(0);
1006 fprintf(stderr, "\tCommand Summary:\n\
1007 \t-4 Use IPv4\n\
1008 \t-6 Use IPv6\n\
1009 \t-D Enable the debug socket option\n\
1010 \t-d Detach from stdin\n\
1011 \t-h This help text\n\
1012 \t-I length TCP receive buffer length\n\
1013 \t-i secs\t Delay interval for lines sent, ports scanned\n\
1014 \t-k Keep inbound sockets open for multiple connects\n\
1015 \t-l Listen mode, for inbound connects\n\
1016 \t-n Suppress name/port resolutions\n\
1017 \t-O length TCP send buffer length\n\
1018 \t-P proxyuser\tUsername for proxy authentication\n\
1019 \t-p port\t Specify local port for remote connects\n\
1020 \t-r Randomize remote ports\n\
1021 \t-S Enable the TCP MD5 signature option\n\
1022 \t-s addr\t Local source address\n\
1023 \t-T toskeyword\tSet IP Type of Service\n\
1024 \t-t Answer TELNET negotiation\n\
1025 \t-U Use UNIX domain socket\n\
1026 \t-u UDP mode\n\
1027 \t-V rtable Specify alternate routing table\n\
1028 \t-v Verbose\n\
1029 \t-w secs\t Timeout for connects and final net reads\n\
1030 \t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\
1031 \t-x addr[:port]\tSpecify proxy address and port\n\
1032 \t-z Zero-I/O mode [used for scanning]\n\
1033 Port numbers can be individual or ranges: lo-hi [inclusive]\n");
1034 exit(1);
1035}
1036
1037void
1038usage(int ret)
1039{
1040 fprintf(stderr,
1041 "usage: nc [-46DdhklnrStUuvz] [-I length] [-i interval] [-O length]\n"
1042 "\t [-P proxy_username] [-p source_port] [-s source] [-T ToS]\n"
1043 "\t [-V rtable] [-w timeout] [-X proxy_protocol]\n"
1044 "\t [-x proxy_address[:port]] [destination] [port]\n");
1045 if (ret)
1046 exit(1);
1047}
generated by cgit v1.2.3-55-g6feb (git 2.39.1) at 2026-01-12 10:00:20 +0000