netcat.c revision 241906 
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 * $FreeBSD: head/contrib/netcat/netcat.c 241906 2012-10-22 18:56:31Z delphij $
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 */
76int	dflag;					/* detached, no stdin */
77unsigned int iflag;				/* Interval Flag */
78int	kflag;					/* More than one connect */
79int	lflag;					/* Bind to local port */
80int	nflag;					/* Don't do name look up */
81int	FreeBSD_Oflag;				/* Do not use TCP options */
82char   *Pflag;					/* Proxy username */
83char   *pflag;					/* Localport flag */
84int	rflag;					/* Random ports flag */
85char   *sflag;					/* Source Address */
86int	tflag;					/* Telnet Emulation */
87int	uflag;					/* UDP - Default to TCP */
88int	vflag;					/* Verbosity */
89int	xflag;					/* Socks proxy */
90int	zflag;					/* Port Scan Flag */
91int	Dflag;					/* sodebug */
92int	Iflag;					/* TCP receive buffer size */
93int	Oflag;					/* TCP send buffer size */
94int	Sflag;					/* TCP MD5 signature option */
95int	Tflag = -1;				/* IP Type of Service */
96u_int	rtableid;
97
98int timeout = -1;
99int family = AF_UNSPEC;
100char *portlist[PORT_MAX+1];
101char *unix_dg_tmp_socket;
102
103void	atelnet(int, unsigned char *, unsigned int);
104void	build_ports(char *);
105void	help(void);
106int	local_listen(char *, char *, struct addrinfo);
107void	readwrite(int);
108int	remote_connect(const char *, const char *, struct addrinfo);
109int	timeout_connect(int, const struct sockaddr *, socklen_t);
110int	socks_connect(const char *, const char *, struct addrinfo,
111	    const char *, const char *, struct addrinfo, int, const char *);
112int	udptest(int);
113int	unix_bind(char *);
114int	unix_connect(char *);
115int	unix_listen(char *);
116void	set_common_sockopts(int);
117int	map_tos(char *, int *);
118void	report_connect(const struct sockaddr *, socklen_t);
119void	usage(int);
120
121#ifdef IPSEC
122void	add_ipsec_policy(int, char *);
123
124char	*ipsec_policy[2];
125#endif
126
127int
128main(int argc, char *argv[])
129{
130	int ch, s, ret, socksv, ipsec_count;
131	int numfibs;
132	size_t intsize = sizeof(int);
133	char *host, *uport;
134	struct addrinfo hints;
135	struct servent *sv;
136	socklen_t len;
137	struct sockaddr_storage cliaddr;
138	char *proxy;
139	const char *errstr, *proxyhost = "", *proxyport = NULL;
140	struct addrinfo proxyhints;
141	char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE];
142	struct option longopts[] = {
143		{ "no-tcpopt",	no_argument,	&FreeBSD_Oflag,	1 },
144		{ NULL,		0,		NULL,		0 }
145	};
146
147	ret = 1;
148	ipsec_count = 0;
149	s = 0;
150	socksv = 5;
151	host = NULL;
152	uport = NULL;
153	sv = NULL;
154
155	while ((ch = getopt_long(argc, argv,
156	    "46DdEe:hI:i:klnoO:P:p:rSs:tT:UuV:vw:X:x:z",
157	    longopts, NULL)) != -1) {
158		switch (ch) {
159		case '4':
160			family = AF_INET;
161			break;
162		case '6':
163			family = AF_INET6;
164			break;
165		case 'U':
166			family = AF_UNIX;
167			break;
168		case 'X':
169			if (strcasecmp(optarg, "connect") == 0)
170				socksv = -1; /* HTTP proxy CONNECT */
171			else if (strcmp(optarg, "4") == 0)
172				socksv = 4; /* SOCKS v.4 */
173			else if (strcmp(optarg, "5") == 0)
174				socksv = 5; /* SOCKS v.5 */
175			else
176				errx(1, "unsupported proxy protocol");
177			break;
178		case 'd':
179			dflag = 1;
180			break;
181		case 'e':
182#ifdef IPSEC
183			ipsec_policy[ipsec_count++ % 2] = optarg;
184#else
185			errx(1, "IPsec support unavailable.");
186#endif
187			break;
188		case 'E':
189#ifdef IPSEC
190			ipsec_policy[0] = "in  ipsec esp/transport//require";
191			ipsec_policy[1] = "out ipsec esp/transport//require";
192#else
193			errx(1, "IPsec support unavailable.");
194#endif
195			break;
196		case 'h':
197			help();
198			break;
199		case 'i':
200			iflag = strtonum(optarg, 0, UINT_MAX, &errstr);
201			if (errstr)
202				errx(1, "interval %s: %s", errstr, optarg);
203			break;
204		case 'k':
205			kflag = 1;
206			break;
207		case 'l':
208			lflag = 1;
209			break;
210		case 'n':
211			nflag = 1;
212			break;
213		case 'o':
214			fprintf(stderr, "option -o is deprecated.\n");
215			break;
216		case 'P':
217			Pflag = optarg;
218			break;
219		case 'p':
220			pflag = optarg;
221			break;
222		case 'r':
223			rflag = 1;
224			break;
225		case 's':
226			sflag = optarg;
227			break;
228		case 't':
229			tflag = 1;
230			break;
231		case 'u':
232			uflag = 1;
233			break;
234		case 'V':
235			if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1)
236				errx(1, "Multiple FIBS not supported");
237			rtableid = (unsigned int)strtonum(optarg, 0,
238			    numfibs - 1, &errstr);
239			if (errstr)
240				errx(1, "rtable %s: %s", errstr, optarg);
241			break;
242		case 'v':
243			vflag = 1;
244			break;
245		case 'w':
246			timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr);
247			if (errstr)
248				errx(1, "timeout %s: %s", errstr, optarg);
249			timeout *= 1000;
250			break;
251		case 'x':
252			xflag = 1;
253			if ((proxy = strdup(optarg)) == NULL)
254				err(1, NULL);
255			break;
256		case 'z':
257			zflag = 1;
258			break;
259		case 'D':
260			Dflag = 1;
261			break;
262		case 'I':
263			Iflag = strtonum(optarg, 1, 65536 << 14, &errstr);
264			if (errstr != NULL)
265				errx(1, "TCP receive window %s: %s",
266				    errstr, optarg);
267			break;
268		case 'O':
269			Oflag = strtonum(optarg, 1, 65536 << 14, &errstr);
270			if (errstr != NULL) {
271			    if (strcmp(errstr, "invalid") != 0)
272				errx(1, "TCP send window %s: %s",
273				    errstr, optarg);
274			}
275			break;
276		case 'S':
277			Sflag = 1;
278			break;
279		case 'T':
280			errstr = NULL;
281			errno = 0;
282			if (map_tos(optarg, &Tflag))
283				break;
284			if (strlen(optarg) > 1 && optarg[0] == '0' &&
285			    optarg[1] == 'x')
286				Tflag = (int)strtol(optarg, NULL, 16);
287			else
288				Tflag = (int)strtonum(optarg, 0, 255,
289				    &errstr);
290			if (Tflag < 0 || Tflag > 255 || errstr || errno)
291				errx(1, "illegal tos value %s", optarg);
292			break;
293		default:
294			usage(1);
295		}
296	}
297	argc -= optind;
298	argv += optind;
299
300	/* Cruft to make sure options are clean, and used properly. */
301	if (argv[0] && !argv[1] && family == AF_UNIX) {
302		host = argv[0];
303		uport = NULL;
304	} else if (argv[0] && !argv[1]) {
305		if  (!lflag)
306			usage(1);
307		uport = argv[0];
308		host = NULL;
309	} else if (argv[0] && argv[1]) {
310		host = argv[0];
311		uport = argv[1];
312	} else
313		usage(1);
314
315	if (lflag && sflag)
316		errx(1, "cannot use -s and -l");
317	if (lflag && pflag)
318		errx(1, "cannot use -p and -l");
319	if (lflag && zflag)
320		errx(1, "cannot use -z and -l");
321	if (!lflag && kflag)
322		errx(1, "must use -l with -k");
323
324	/* Get name of temporary socket for unix datagram client */
325	if ((family == AF_UNIX) && uflag && !lflag) {
326		if (sflag) {
327			unix_dg_tmp_socket = sflag;
328		} else {
329			strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX",
330				UNIX_DG_TMP_SOCKET_SIZE);
331			if (mktemp(unix_dg_tmp_socket_buf) == NULL)
332				err(1, "mktemp");
333			unix_dg_tmp_socket = unix_dg_tmp_socket_buf;
334		}
335	}
336
337	/* Initialize addrinfo structure. */
338	if (family != AF_UNIX) {
339		memset(&hints, 0, sizeof(struct addrinfo));
340		hints.ai_family = family;
341		hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM;
342		hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP;
343		if (nflag)
344			hints.ai_flags |= AI_NUMERICHOST;
345	}
346
347	if (xflag) {
348		if (uflag)
349			errx(1, "no proxy support for UDP mode");
350
351		if (lflag)
352			errx(1, "no proxy support for listen");
353
354		if (family == AF_UNIX)
355			errx(1, "no proxy support for unix sockets");
356
357		/* XXX IPv6 transport to proxy would probably work */
358		if (family == AF_INET6)
359			errx(1, "no proxy support for IPv6");
360
361		if (sflag)
362			errx(1, "no proxy support for local source address");
363
364		proxyhost = strsep(&proxy, ":");
365		proxyport = proxy;
366
367		memset(&proxyhints, 0, sizeof(struct addrinfo));
368		proxyhints.ai_family = family;
369		proxyhints.ai_socktype = SOCK_STREAM;
370		proxyhints.ai_protocol = IPPROTO_TCP;
371		if (nflag)
372			proxyhints.ai_flags |= AI_NUMERICHOST;
373	}
374
375	if (lflag) {
376		int connfd;
377		ret = 0;
378
379		if (family == AF_UNIX) {
380			if (uflag)
381				s = unix_bind(host);
382			else
383				s = unix_listen(host);
384		}
385
386		/* Allow only one connection at a time, but stay alive. */
387		for (;;) {
388			if (family != AF_UNIX)
389				s = local_listen(host, uport, hints);
390			if (s < 0)
391				err(1, NULL);
392			/*
393			 * For UDP and -k, don't connect the socket, let it
394			 * receive datagrams from multiple socket pairs.
395			 */
396			if (uflag && kflag)
397				readwrite(s);
398			/*
399			 * For UDP and not -k, we will use recvfrom() initially
400			 * to wait for a caller, then use the regular functions
401			 * to talk to the caller.
402			 */
403			else if (uflag && !kflag) {
404				int rv, plen;
405				char buf[16384];
406				struct sockaddr_storage z;
407
408				len = sizeof(z);
409				plen = 2048;
410				rv = recvfrom(s, buf, plen, MSG_PEEK,
411				    (struct sockaddr *)&z, &len);
412				if (rv < 0)
413					err(1, "recvfrom");
414
415				rv = connect(s, (struct sockaddr *)&z, len);
416				if (rv < 0)
417					err(1, "connect");
418
419				if (vflag)
420					report_connect((struct sockaddr *)&z, len);
421
422				readwrite(s);
423			} else {
424				len = sizeof(cliaddr);
425				connfd = accept(s, (struct sockaddr *)&cliaddr,
426				    &len);
427				if (connfd == -1)
428					err(1, "accept");
429
430				if (vflag)
431					report_connect((struct sockaddr *)&cliaddr, len);
432
433				readwrite(connfd);
434				close(connfd);
435			}
436
437			if (family != AF_UNIX)
438				close(s);
439			else if (uflag) {
440				if (connect(s, NULL, 0) < 0)
441					err(1, "connect");
442			}
443
444			if (!kflag)
445				break;
446		}
447	} else if (family == AF_UNIX) {
448		ret = 0;
449
450		if ((s = unix_connect(host)) > 0 && !zflag) {
451			readwrite(s);
452			close(s);
453		} else
454			ret = 1;
455
456		if (uflag)
457			unlink(unix_dg_tmp_socket);
458		exit(ret);
459
460	} else {
461		int i = 0;
462
463		/* Construct the portlist[] array. */
464		build_ports(uport);
465
466		/* Cycle through portlist, connecting to each port. */
467		for (i = 0; portlist[i] != NULL; i++) {
468			if (s)
469				close(s);
470
471			if (xflag)
472				s = socks_connect(host, portlist[i], hints,
473				    proxyhost, proxyport, proxyhints, socksv,
474				    Pflag);
475			else
476				s = remote_connect(host, portlist[i], hints);
477
478			if (s < 0)
479				continue;
480
481			ret = 0;
482			if (vflag || zflag) {
483				/* For UDP, make sure we are connected. */
484				if (uflag) {
485					if (udptest(s) == -1) {
486						ret = 1;
487						continue;
488					}
489				}
490
491				/* Don't look up port if -n. */
492				if (nflag)
493					sv = NULL;
494				else {
495					sv = getservbyport(
496					    ntohs(atoi(portlist[i])),
497					    uflag ? "udp" : "tcp");
498				}
499
500				fprintf(stderr,
501				    "Connection to %s %s port [%s/%s] "
502				    "succeeded!\n", host, portlist[i],
503				    uflag ? "udp" : "tcp",
504				    sv ? sv->s_name : "*");
505			}
506			if (!zflag)
507				readwrite(s);
508		}
509	}
510
511	if (s)
512		close(s);
513
514	exit(ret);
515}
516
517/*
518 * unix_bind()
519 * Returns a unix socket bound to the given path
520 */
521int
522unix_bind(char *path)
523{
524	struct sockaddr_un sun;
525	int s;
526
527	/* Create unix domain socket. */
528	if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM,
529	     0)) < 0)
530		return (-1);
531
532	memset(&sun, 0, sizeof(struct sockaddr_un));
533	sun.sun_family = AF_UNIX;
534
535	if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >=
536	    sizeof(sun.sun_path)) {
537		close(s);
538		errno = ENAMETOOLONG;
539		return (-1);
540	}
541
542	if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
543		close(s);
544		return (-1);
545	}
546	return (s);
547}
548
549/*
550 * unix_connect()
551 * Returns a socket connected to a local unix socket. Returns -1 on failure.
552 */
553int
554unix_connect(char *path)
555{
556	struct sockaddr_un sun;
557	int s;
558
559	if (uflag) {
560		if ((s = unix_bind(unix_dg_tmp_socket)) < 0)
561			return (-1);
562	} else {
563		if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
564			return (-1);
565	}
566	(void)fcntl(s, F_SETFD, 1);
567
568	memset(&sun, 0, sizeof(struct sockaddr_un));
569	sun.sun_family = AF_UNIX;
570
571	if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >=
572	    sizeof(sun.sun_path)) {
573		close(s);
574		errno = ENAMETOOLONG;
575		return (-1);
576	}
577	if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
578		close(s);
579		return (-1);
580	}
581	return (s);
582
583}
584
585/*
586 * unix_listen()
587 * Create a unix domain socket, and listen on it.
588 */
589int
590unix_listen(char *path)
591{
592	int s;
593	if ((s = unix_bind(path)) < 0)
594		return (-1);
595
596	if (listen(s, 5) < 0) {
597		close(s);
598		return (-1);
599	}
600	return (s);
601}
602
603/*
604 * remote_connect()
605 * Returns a socket connected to a remote host. Properly binds to a local
606 * port or source address if needed. Returns -1 on failure.
607 */
608int
609remote_connect(const char *host, const char *port, struct addrinfo hints)
610{
611	struct addrinfo *res, *res0;
612	int s, error, on = 1;
613
614	if ((error = getaddrinfo(host, port, &hints, &res)))
615		errx(1, "getaddrinfo: %s", gai_strerror(error));
616
617	res0 = res;
618	do {
619		if ((s = socket(res0->ai_family, res0->ai_socktype,
620		    res0->ai_protocol)) < 0)
621			continue;
622#ifdef IPSEC
623		if (ipsec_policy[0] != NULL)
624			add_ipsec_policy(s, ipsec_policy[0]);
625		if (ipsec_policy[1] != NULL)
626			add_ipsec_policy(s, ipsec_policy[1]);
627#endif
628
629		if (rtableid) {
630			if (setsockopt(s, SOL_SOCKET, SO_SETFIB, &rtableid,
631			    sizeof(rtableid)) == -1)
632				err(1, "setsockopt(.., SO_SETFIB, %u, ..)",
633				    rtableid);
634		}
635
636		/* Bind to a local port or source address if specified. */
637		if (sflag || pflag) {
638			struct addrinfo ahints, *ares;
639
640			/* try IP_BINDANY, but don't insist */
641			setsockopt(s, IPPROTO_IP, IP_BINDANY, &on, sizeof(on));
642			memset(&ahints, 0, sizeof(struct addrinfo));
643			ahints.ai_family = res0->ai_family;
644			ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM;
645			ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP;
646			ahints.ai_flags = AI_PASSIVE;
647			if ((error = getaddrinfo(sflag, pflag, &ahints, &ares)))
648				errx(1, "getaddrinfo: %s", gai_strerror(error));
649
650			if (bind(s, (struct sockaddr *)ares->ai_addr,
651			    ares->ai_addrlen) < 0)
652				errx(1, "bind failed: %s", strerror(errno));
653			freeaddrinfo(ares);
654		}
655
656		set_common_sockopts(s);
657
658		if (timeout_connect(s, res0->ai_addr, res0->ai_addrlen) == 0)
659			break;
660		else if (vflag)
661			warn("connect to %s port %s (%s) failed", host, port,
662			    uflag ? "udp" : "tcp");
663
664		close(s);
665		s = -1;
666	} while ((res0 = res0->ai_next) != NULL);
667
668	freeaddrinfo(res);
669
670	return (s);
671}
672
673int
674timeout_connect(int s, const struct sockaddr *name, socklen_t namelen)
675{
676	struct pollfd pfd;
677	socklen_t optlen;
678	int flags, optval;
679	int ret;
680
681	if (timeout != -1) {
682		flags = fcntl(s, F_GETFL, 0);
683		if (fcntl(s, F_SETFL, flags | O_NONBLOCK) == -1)
684			err(1, "set non-blocking mode");
685	}
686
687	if ((ret = connect(s, name, namelen)) != 0 && errno == EINPROGRESS) {
688		pfd.fd = s;
689		pfd.events = POLLOUT;
690		if ((ret = poll(&pfd, 1, timeout)) == 1) {
691			optlen = sizeof(optval);
692			if ((ret = getsockopt(s, SOL_SOCKET, SO_ERROR,
693			    &optval, &optlen)) == 0) {
694				errno = optval;
695				ret = optval == 0 ? 0 : -1;
696			}
697		} else if (ret == 0) {
698			errno = ETIMEDOUT;
699			ret = -1;
700		} else
701			err(1, "poll failed");
702	}
703
704	if (timeout != -1 && fcntl(s, F_SETFL, flags) == -1)
705		err(1, "restoring flags");
706
707	return (ret);
708}
709
710/*
711 * local_listen()
712 * Returns a socket listening on a local port, binds to specified source
713 * address. Returns -1 on failure.
714 */
715int
716local_listen(char *host, char *port, struct addrinfo hints)
717{
718	struct addrinfo *res, *res0;
719	int s, ret, x = 1;
720	int error;
721
722	/* Allow nodename to be null. */
723	hints.ai_flags |= AI_PASSIVE;
724
725	/*
726	 * In the case of binding to a wildcard address
727	 * default to binding to an ipv4 address.
728	 */
729	if (host == NULL && hints.ai_family == AF_UNSPEC)
730		hints.ai_family = AF_INET;
731
732	if ((error = getaddrinfo(host, port, &hints, &res)))
733		errx(1, "getaddrinfo: %s", gai_strerror(error));
734
735	res0 = res;
736	do {
737		if ((s = socket(res0->ai_family, res0->ai_socktype,
738		    res0->ai_protocol)) < 0)
739			continue;
740
741		if (rtableid) {
742			ret = setsockopt(s, SOL_SOCKET, SO_SETFIB, &rtableid,
743			    sizeof(rtableid));
744			if (ret == -1)
745				err(1, "setsockopt(.., SO_SETFIB, %u, ..)",
746				    rtableid);
747		}
748
749		ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x));
750		if (ret == -1)
751			err(1, NULL);
752#ifdef IPSEC
753		if (ipsec_policy[0] != NULL)
754			add_ipsec_policy(s, ipsec_policy[0]);
755		if (ipsec_policy[1] != NULL)
756			add_ipsec_policy(s, ipsec_policy[1]);
757#endif
758		if (FreeBSD_Oflag) {
759			if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT,
760			    &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1)
761				err(1, "disable TCP options");
762		}
763
764		if (bind(s, (struct sockaddr *)res0->ai_addr,
765		    res0->ai_addrlen) == 0)
766			break;
767
768		close(s);
769		s = -1;
770	} while ((res0 = res0->ai_next) != NULL);
771
772	if (!uflag && s != -1) {
773		if (listen(s, 1) < 0)
774			err(1, "listen");
775	}
776
777	freeaddrinfo(res);
778
779	return (s);
780}
781
782/*
783 * readwrite()
784 * Loop that polls on the network file descriptor and stdin.
785 */
786void
787readwrite(int nfd)
788{
789	struct pollfd pfd[2];
790	unsigned char buf[16384];
791	int n, wfd = fileno(stdin);
792	int lfd = fileno(stdout);
793	int plen;
794
795	plen = 2048;
796
797	/* Setup Network FD */
798	pfd[0].fd = nfd;
799	pfd[0].events = POLLIN;
800
801	/* Set up STDIN FD. */
802	pfd[1].fd = wfd;
803	pfd[1].events = POLLIN;
804
805	while (pfd[0].fd != -1) {
806		if (iflag)
807			sleep(iflag);
808
809		if ((n = poll(pfd, 2 - dflag, timeout)) < 0) {
810			close(nfd);
811			err(1, "Polling Error");
812		}
813
814		if (n == 0)
815			return;
816
817		if (pfd[0].revents & POLLIN) {
818			if ((n = read(nfd, buf, plen)) < 0)
819				return;
820			else if (n == 0) {
821				shutdown(nfd, SHUT_RD);
822				pfd[0].fd = -1;
823				pfd[0].events = 0;
824			} else {
825				if (tflag)
826					atelnet(nfd, buf, n);
827				if (atomicio(vwrite, lfd, buf, n) != n)
828					return;
829			}
830		}
831
832		if (!dflag && pfd[1].revents & POLLIN) {
833			if ((n = read(wfd, buf, plen)) < 0)
834				return;
835			else if (n == 0) {
836				shutdown(nfd, SHUT_WR);
837				pfd[1].fd = -1;
838				pfd[1].events = 0;
839			} else {
840				if (atomicio(vwrite, nfd, buf, n) != n)
841					return;
842			}
843		}
844	}
845}
846
847/* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */
848void
849atelnet(int nfd, unsigned char *buf, unsigned int size)
850{
851	unsigned char *p, *end;
852	unsigned char obuf[4];
853
854	if (size < 3)
855		return;
856	end = buf + size - 2;
857
858	for (p = buf; p < end; p++) {
859		if (*p != IAC)
860			continue;
861
862		obuf[0] = IAC;
863		p++;
864		if ((*p == WILL) || (*p == WONT))
865			obuf[1] = DONT;
866		else if ((*p == DO) || (*p == DONT))
867			obuf[1] = WONT;
868		else
869			continue;
870
871		p++;
872		obuf[2] = *p;
873		if (atomicio(vwrite, nfd, obuf, 3) != 3)
874			warn("Write Error!");
875	}
876}
877
878/*
879 * build_ports()
880 * Build an array of ports in portlist[], listing each port
881 * that we should try to connect to.
882 */
883void
884build_ports(char *p)
885{
886	const char *errstr;
887	char *n;
888	int hi, lo, cp;
889	int x = 0;
890
891	if ((n = strchr(p, '-')) != NULL) {
892		*n = '\0';
893		n++;
894
895		/* Make sure the ports are in order: lowest->highest. */
896		hi = strtonum(n, 1, PORT_MAX, &errstr);
897		if (errstr)
898			errx(1, "port number %s: %s", errstr, n);
899		lo = strtonum(p, 1, PORT_MAX, &errstr);
900		if (errstr)
901			errx(1, "port number %s: %s", errstr, p);
902
903		if (lo > hi) {
904			cp = hi;
905			hi = lo;
906			lo = cp;
907		}
908
909		/* Load ports sequentially. */
910		for (cp = lo; cp <= hi; cp++) {
911			portlist[x] = calloc(1, PORT_MAX_LEN);
912			if (portlist[x] == NULL)
913				err(1, NULL);
914			snprintf(portlist[x], PORT_MAX_LEN, "%d", cp);
915			x++;
916		}
917
918		/* Randomly swap ports. */
919		if (rflag) {
920			int y;
921			char *c;
922
923			for (x = 0; x <= (hi - lo); x++) {
924				y = (arc4random() & 0xFFFF) % (hi - lo);
925				c = portlist[x];
926				portlist[x] = portlist[y];
927				portlist[y] = c;
928			}
929		}
930	} else {
931		hi = strtonum(p, 1, PORT_MAX, &errstr);
932		if (errstr)
933			errx(1, "port number %s: %s", errstr, p);
934		portlist[0] = strdup(p);
935		if (portlist[0] == NULL)
936			err(1, NULL);
937	}
938}
939
940/*
941 * udptest()
942 * Do a few writes to see if the UDP port is there.
943 * Fails once PF state table is full.
944 */
945int
946udptest(int s)
947{
948	int i, ret;
949
950	for (i = 0; i <= 3; i++) {
951		if (write(s, "X", 1) == 1)
952			ret = 1;
953		else
954			ret = -1;
955	}
956	return (ret);
957}
958
959void
960set_common_sockopts(int s)
961{
962	int x = 1;
963
964	if (Sflag) {
965		if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG,
966			&x, sizeof(x)) == -1)
967			err(1, NULL);
968	}
969	if (Dflag) {
970		if (setsockopt(s, SOL_SOCKET, SO_DEBUG,
971			&x, sizeof(x)) == -1)
972			err(1, NULL);
973	}
974	if (Tflag != -1) {
975		if (setsockopt(s, IPPROTO_IP, IP_TOS,
976		    &Tflag, sizeof(Tflag)) == -1)
977			err(1, "set IP ToS");
978	}
979	if (Iflag) {
980		if (setsockopt(s, SOL_SOCKET, SO_RCVBUF,
981		    &Iflag, sizeof(Iflag)) == -1)
982			err(1, "set TCP receive buffer size");
983	}
984	if (Oflag) {
985		if (setsockopt(s, SOL_SOCKET, SO_SNDBUF,
986		    &Oflag, sizeof(Oflag)) == -1)
987			err(1, "set TCP send buffer size");
988	}
989	if (FreeBSD_Oflag) {
990		if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT,
991		    &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1)
992			err(1, "disable TCP options");
993	}
994}
995
996int
997map_tos(char *s, int *val)
998{
999	/* DiffServ Codepoints and other TOS mappings */
1000	const struct toskeywords {
1001		const char	*keyword;
1002		int		 val;
1003	} *t, toskeywords[] = {
1004		{ "af11",		IPTOS_DSCP_AF11 },
1005		{ "af12",		IPTOS_DSCP_AF12 },
1006		{ "af13",		IPTOS_DSCP_AF13 },
1007		{ "af21",		IPTOS_DSCP_AF21 },
1008		{ "af22",		IPTOS_DSCP_AF22 },
1009		{ "af23",		IPTOS_DSCP_AF23 },
1010		{ "af31",		IPTOS_DSCP_AF31 },
1011		{ "af32",		IPTOS_DSCP_AF32 },
1012		{ "af33",		IPTOS_DSCP_AF33 },
1013		{ "af41",		IPTOS_DSCP_AF41 },
1014		{ "af42",		IPTOS_DSCP_AF42 },
1015		{ "af43",		IPTOS_DSCP_AF43 },
1016		{ "critical",		IPTOS_PREC_CRITIC_ECP },
1017		{ "cs0",		IPTOS_DSCP_CS0 },
1018		{ "cs1",		IPTOS_DSCP_CS1 },
1019		{ "cs2",		IPTOS_DSCP_CS2 },
1020		{ "cs3",		IPTOS_DSCP_CS3 },
1021		{ "cs4",		IPTOS_DSCP_CS4 },
1022		{ "cs5",		IPTOS_DSCP_CS5 },
1023		{ "cs6",		IPTOS_DSCP_CS6 },
1024		{ "cs7",		IPTOS_DSCP_CS7 },
1025		{ "ef",			IPTOS_DSCP_EF },
1026		{ "inetcontrol",	IPTOS_PREC_INTERNETCONTROL },
1027		{ "lowdelay",		IPTOS_LOWDELAY },
1028		{ "netcontrol",		IPTOS_PREC_NETCONTROL },
1029		{ "reliability",	IPTOS_RELIABILITY },
1030		{ "throughput",		IPTOS_THROUGHPUT },
1031		{ NULL, 		-1 },
1032	};
1033
1034	for (t = toskeywords; t->keyword != NULL; t++) {
1035		if (strcmp(s, t->keyword) == 0) {
1036			*val = t->val;
1037			return (1);
1038		}
1039	}
1040
1041	return (0);
1042}
1043
1044void
1045report_connect(const struct sockaddr *sa, socklen_t salen)
1046{
1047	char remote_host[NI_MAXHOST];
1048	char remote_port[NI_MAXSERV];
1049	int herr;
1050	int flags = NI_NUMERICSERV;
1051
1052	if (nflag)
1053		flags |= NI_NUMERICHOST;
1054
1055	if ((herr = getnameinfo(sa, salen,
1056	    remote_host, sizeof(remote_host),
1057	    remote_port, sizeof(remote_port),
1058	    flags)) != 0) {
1059		if (herr == EAI_SYSTEM)
1060			err(1, "getnameinfo");
1061		else
1062			errx(1, "getnameinfo: %s", gai_strerror(herr));
1063	}
1064
1065	fprintf(stderr,
1066	    "Connection from %s %s "
1067	    "received!\n", remote_host, remote_port);
1068}
1069
1070void
1071help(void)
1072{
1073	usage(0);
1074	fprintf(stderr, "\tCommand Summary:\n\
1075	\t-4		Use IPv4\n\
1076	\t-6		Use IPv6\n\
1077	\t-D		Enable the debug socket option\n\
1078	\t-d		Detach from stdin\n");
1079#ifdef IPSEC
1080	fprintf(stderr, "\
1081	\t-E		Use IPsec ESP\n\
1082	\t-e policy	Use specified IPsec policy\n");
1083#endif
1084	fprintf(stderr, "\
1085	\t-h		This help text\n\
1086	\t-I length	TCP receive buffer length\n\
1087	\t-i secs\t	Delay interval for lines sent, ports scanned\n\
1088	\t-k		Keep inbound sockets open for multiple connects\n\
1089	\t-l		Listen mode, for inbound connects\n\
1090	\t-n		Suppress name/port resolutions\n\
1091	\t--no-tcpopt	Disable TCP options\n\
1092	\t-O length	TCP send buffer length\n\
1093	\t-P proxyuser\tUsername for proxy authentication\n\
1094	\t-p port\t	Specify local port for remote connects\n\
1095	\t-r		Randomize remote ports\n\
1096	\t-S		Enable the TCP MD5 signature option\n\
1097	\t-s addr\t	Local source address\n\
1098	\t-T toskeyword\tSet IP Type of Service\n\
1099	\t-t		Answer TELNET negotiation\n\
1100	\t-U		Use UNIX domain socket\n\
1101	\t-u		UDP mode\n\
1102	\t-V rtable	Specify alternate routing table\n\
1103	\t-v		Verbose\n\
1104	\t-w secs\t	Timeout for connects and final net reads\n\
1105	\t-X proto	Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\
1106	\t-x addr[:port]\tSpecify proxy address and port\n\
1107	\t-z		Zero-I/O mode [used for scanning]\n\
1108	Port numbers can be individual or ranges: lo-hi [inclusive]\n");
1109#ifdef IPSEC
1110	fprintf(stderr, "See ipsec_set_policy(3) for -e argument format\n");
1111#endif
1112	exit(1);
1113}
1114
1115#ifdef IPSEC
1116void
1117add_ipsec_policy(int s, char *policy)
1118{
1119	char *raw;
1120	int e;
1121
1122	raw = ipsec_set_policy(policy, strlen(policy));
1123	if (raw == NULL)
1124		errx(1, "ipsec_set_policy `%s': %s", policy,
1125		     ipsec_strerror());
1126	e = setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, raw,
1127			ipsec_get_policylen(raw));
1128	if (e < 0)
1129		err(1, "ipsec policy cannot be configured");
1130	free(raw);
1131	if (vflag)
1132		fprintf(stderr, "ipsec policy configured: `%s'\n", policy);
1133	return;
1134}
1135#endif /* IPSEC */
1136
1137void
1138usage(int ret)
1139{
1140	fprintf(stderr,
1141#ifdef IPSEC
1142	    "usage: nc [-46DdEhklnrStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n"
1143#else
1144	    "usage: nc [-46DdhklnrStUuvz] [-I length] [-i interval] [-O length]\n"
1145#endif
1146	    "\t  [-P proxy_username] [-p source_port] [-s source] [-T ToS]\n"
1147	    "\t  [-V rtable] [-w timeout] [-X proxy_protocol]\n"
1148	    "\t  [-x proxy_address[:port]] [destination] [port]\n");
1149	if (ret)
1150		exit(1);
1151}
1152