xref: /freebsd/contrib/netcat/netcat.c (revision f976241773df2260e6170317080761d1c5814fe5)
1 /* $OpenBSD: netcat.c,v 1.130 2015/07/26 19:12:28 chl 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 <errno.h>
37 #include <stdio.h>
38 #include <sys/arb.h>
39 #include <sys/limits.h>
40 #include <sys/types.h>
41 #include <sys/sbuf.h>
42 #include <sys/socket.h>
43 #include <sys/sysctl.h>
44 #include <sys/qmath.h>
45 #include <sys/stats.h>
46 #include <sys/time.h>
47 #include <sys/uio.h>
48 #include <sys/un.h>
49 
50 #include <netinet/in.h>
51 #ifdef IPSEC
52 #include <netipsec/ipsec.h>
53 #endif
54 #include <netinet/tcp.h>
55 #include <netinet/ip.h>
56 #include <arpa/telnet.h>
57 
58 #include <err.h>
59 #include <getopt.h>
60 #include <fcntl.h>
61 #include <limits.h>
62 #include <netdb.h>
63 #include <poll.h>
64 #include <signal.h>
65 #include <stdarg.h>
66 #include <stdlib.h>
67 #include <string.h>
68 #include <unistd.h>
69 #include "atomicio.h"
70 
71 #ifndef SUN_LEN
72 #define SUN_LEN(su) \
73 	(sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path))
74 #endif
75 
76 #define PORT_MAX	65535
77 #define PORT_MAX_LEN	6
78 #define UNIX_DG_TMP_SOCKET_SIZE	19
79 
80 #define POLL_STDIN 0
81 #define POLL_NETOUT 1
82 #define POLL_NETIN 2
83 #define POLL_STDOUT 3
84 #define BUFSIZE 16384
85 
86 /* Command Line Options */
87 int	dflag;					/* detached, no stdin */
88 int	Fflag;					/* fdpass sock to stdout */
89 unsigned int iflag;				/* Interval Flag */
90 int	kflag;					/* More than one connect */
91 int	lflag;					/* Bind to local port */
92 int	FreeBSD_Mflag;				/* Measure using stats(3) */
93 int	Nflag;					/* shutdown() network socket */
94 int	nflag;					/* Don't do name look up */
95 int	FreeBSD_Oflag;				/* Do not use TCP options */
96 char   *Pflag;					/* Proxy username */
97 char   *pflag;					/* Localport flag */
98 int	rflag;					/* Random ports flag */
99 char   *sflag;					/* Source Address */
100 int	tflag;					/* Telnet Emulation */
101 int	uflag;					/* UDP - Default to TCP */
102 int	vflag;					/* Verbosity */
103 int	xflag;					/* Socks proxy */
104 int	zflag;					/* Port Scan Flag */
105 int	Dflag;					/* sodebug */
106 int	Iflag;					/* TCP receive buffer size */
107 int	Oflag;					/* TCP send buffer size */
108 int	Sflag;					/* TCP MD5 signature option */
109 int	Tflag = -1;				/* IP Type of Service */
110 int	rtableid = -1;
111 
112 int timeout = -1;
113 int family = AF_UNSPEC;
114 char *portlist[PORT_MAX+1];
115 char *unix_dg_tmp_socket;
116 
117 void	atelnet(int, unsigned char *, unsigned int);
118 void	build_ports(char *);
119 void	help(void);
120 int	local_listen(char *, char *, struct addrinfo);
121 void	readwrite(int);
122 void	fdpass(int nfd) __attribute__((noreturn));
123 int	remote_connect(const char *, const char *, struct addrinfo);
124 int	timeout_connect(int, const struct sockaddr *, socklen_t);
125 int	socks_connect(const char *, const char *, struct addrinfo,
126 	    const char *, const char *, struct addrinfo, int, const char *);
127 int	udptest(int);
128 int	unix_bind(char *);
129 int	unix_connect(char *);
130 int	unix_listen(char *);
131 void	FreeBSD_stats_setup(int);
132 void	FreeBSD_stats_print(int);
133 void	set_common_sockopts(int, int);
134 int	map_tos(char *, int *);
135 void	report_connect(const struct sockaddr *, socklen_t);
136 void	usage(int);
137 ssize_t drainbuf(int, unsigned char *, size_t *);
138 ssize_t fillbuf(int, unsigned char *, size_t *);
139 
140 #ifdef IPSEC
141 void	add_ipsec_policy(int, int, char *);
142 
143 char	*ipsec_policy[2];
144 #endif
145 
146 int
147 main(int argc, char *argv[])
148 {
149 	int ch, s, ret, socksv, ipsec_count;
150 	int numfibs;
151 	size_t intsize = sizeof(int);
152 	char *host, *uport;
153 	struct addrinfo hints;
154 	struct servent *sv;
155 	socklen_t len;
156 	struct sockaddr_storage cliaddr;
157 	char *proxy;
158 	const char *errstr, *proxyhost = "", *proxyport = NULL;
159 	struct addrinfo proxyhints;
160 	char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE];
161 	struct option longopts[] = {
162 		{ "no-tcpopt",	no_argument,	&FreeBSD_Oflag,	1 },
163 		{ NULL,		0,		NULL,		0 }
164 	};
165 
166 	ret = 1;
167 	ipsec_count = 0;
168 	s = 0;
169 	socksv = 5;
170 	host = NULL;
171 	uport = NULL;
172 	sv = NULL;
173 
174 	signal(SIGPIPE, SIG_IGN);
175 
176 	while ((ch = getopt_long(argc, argv,
177 	    "46DdEe:FhI:i:klMNnoO:P:p:rSs:tT:UuV:vw:X:x:z",
178 	    longopts, NULL)) != -1) {
179 		switch (ch) {
180 		case '4':
181 			family = AF_INET;
182 			break;
183 		case '6':
184 			family = AF_INET6;
185 			break;
186 		case 'U':
187 			family = AF_UNIX;
188 			break;
189 		case 'X':
190 			if (strcasecmp(optarg, "connect") == 0)
191 				socksv = -1; /* HTTP proxy CONNECT */
192 			else if (strcmp(optarg, "4") == 0)
193 				socksv = 4; /* SOCKS v.4 */
194 			else if (strcmp(optarg, "5") == 0)
195 				socksv = 5; /* SOCKS v.5 */
196 			else
197 				errx(1, "unsupported proxy protocol");
198 			break;
199 		case 'd':
200 			dflag = 1;
201 			break;
202 		case 'e':
203 #ifdef IPSEC
204 			ipsec_policy[ipsec_count++ % 2] = optarg;
205 #else
206 			errx(1, "IPsec support unavailable.");
207 #endif
208 			break;
209 		case 'E':
210 #ifdef IPSEC
211 			ipsec_policy[0] = "in  ipsec esp/transport//require";
212 			ipsec_policy[1] = "out ipsec esp/transport//require";
213 #else
214 			errx(1, "IPsec support unavailable.");
215 #endif
216 			break;
217 		case 'F':
218 			Fflag = 1;
219 			break;
220 		case 'h':
221 			help();
222 			break;
223 		case 'i':
224 			iflag = strtonum(optarg, 0, UINT_MAX, &errstr);
225 			if (errstr)
226 				errx(1, "interval %s: %s", errstr, optarg);
227 			break;
228 		case 'k':
229 			kflag = 1;
230 			break;
231 		case 'l':
232 			lflag = 1;
233 			break;
234 		case 'M':
235 #ifndef WITH_STATS
236 			errx(1, "-M requires stats(3) support");
237 #else
238 			FreeBSD_Mflag = 1;
239 #endif
240 			break;
241 		case 'N':
242 			Nflag = 1;
243 			break;
244 		case 'n':
245 			nflag = 1;
246 			break;
247 		case 'o':
248 			fprintf(stderr, "option -o is deprecated.\n");
249 			break;
250 		case 'P':
251 			Pflag = optarg;
252 			break;
253 		case 'p':
254 			pflag = optarg;
255 			break;
256 		case 'r':
257 			rflag = 1;
258 			break;
259 		case 's':
260 			sflag = optarg;
261 			break;
262 		case 't':
263 			tflag = 1;
264 			break;
265 		case 'u':
266 			uflag = 1;
267 			break;
268 		case 'V':
269 			if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1)
270 				errx(1, "Multiple FIBS not supported");
271 			rtableid = (int)strtonum(optarg, 0,
272 			    numfibs - 1, &errstr);
273 			if (errstr)
274 				errx(1, "rtable %s: %s", errstr, optarg);
275 			break;
276 		case 'v':
277 			vflag = 1;
278 			break;
279 		case 'w':
280 			timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr);
281 			if (errstr)
282 				errx(1, "timeout %s: %s", errstr, optarg);
283 			timeout *= 1000;
284 			break;
285 		case 'x':
286 			xflag = 1;
287 			if ((proxy = strdup(optarg)) == NULL)
288 				err(1, NULL);
289 			break;
290 		case 'z':
291 			zflag = 1;
292 			break;
293 		case 'D':
294 			Dflag = 1;
295 			break;
296 		case 'I':
297 			Iflag = strtonum(optarg, 1, 65536 << 14, &errstr);
298 			if (errstr != NULL)
299 				errx(1, "TCP receive window %s: %s",
300 				    errstr, optarg);
301 			break;
302 		case 'O':
303 			Oflag = strtonum(optarg, 1, 65536 << 14, &errstr);
304 			if (errstr != NULL) {
305 			    if (strcmp(errstr, "invalid") != 0)
306 				errx(1, "TCP send window %s: %s",
307 				    errstr, optarg);
308 			}
309 			break;
310 		case 'S':
311 			Sflag = 1;
312 			break;
313 		case 'T':
314 			errstr = NULL;
315 			errno = 0;
316 			if (map_tos(optarg, &Tflag))
317 				break;
318 			if (strlen(optarg) > 1 && optarg[0] == '0' &&
319 			    optarg[1] == 'x')
320 				Tflag = (int)strtol(optarg, NULL, 16);
321 			else
322 				Tflag = (int)strtonum(optarg, 0, 255,
323 				    &errstr);
324 			if (Tflag < 0 || Tflag > 255 || errstr || errno)
325 				errx(1, "illegal tos value %s", optarg);
326 			break;
327 		default:
328 			usage(1);
329 		}
330 	}
331 	argc -= optind;
332 	argv += optind;
333 
334 	/* Cruft to make sure options are clean, and used properly. */
335 	if (argv[0] && !argv[1] && family == AF_UNIX) {
336 		host = argv[0];
337 		uport = NULL;
338 	} else if (argv[0] && !argv[1]) {
339 		if  (!lflag)
340 			usage(1);
341 		uport = argv[0];
342 		host = NULL;
343 	} else if (argv[0] && argv[1]) {
344 		host = argv[0];
345 		uport = argv[1];
346 	} else
347 		usage(1);
348 
349 	if (lflag && sflag)
350 		errx(1, "cannot use -s and -l");
351 	if (lflag && pflag)
352 		errx(1, "cannot use -p and -l");
353 	if (lflag && zflag)
354 		errx(1, "cannot use -z and -l");
355 	if (!lflag && kflag)
356 		errx(1, "must use -l with -k");
357 
358 	/* Get name of temporary socket for unix datagram client */
359 	if ((family == AF_UNIX) && uflag && !lflag) {
360 		if (sflag) {
361 			unix_dg_tmp_socket = sflag;
362 		} else {
363 			strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX",
364 				UNIX_DG_TMP_SOCKET_SIZE);
365 			if (mktemp(unix_dg_tmp_socket_buf) == NULL)
366 				err(1, "mktemp");
367 			unix_dg_tmp_socket = unix_dg_tmp_socket_buf;
368 		}
369 	}
370 
371 	/* Initialize addrinfo structure. */
372 	if (family != AF_UNIX) {
373 		memset(&hints, 0, sizeof(struct addrinfo));
374 		hints.ai_family = family;
375 		hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM;
376 		hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP;
377 		if (nflag)
378 			hints.ai_flags |= AI_NUMERICHOST;
379 	}
380 
381 	if (xflag) {
382 		if (uflag)
383 			errx(1, "no proxy support for UDP mode");
384 
385 		if (lflag)
386 			errx(1, "no proxy support for listen");
387 
388 		if (family == AF_UNIX)
389 			errx(1, "no proxy support for unix sockets");
390 
391 		/* XXX IPv6 transport to proxy would probably work */
392 		if (family == AF_INET6)
393 			errx(1, "no proxy support for IPv6");
394 
395 		if (sflag)
396 			errx(1, "no proxy support for local source address");
397 
398 		proxyhost = strsep(&proxy, ":");
399 		proxyport = proxy;
400 
401 		memset(&proxyhints, 0, sizeof(struct addrinfo));
402 		proxyhints.ai_family = family;
403 		proxyhints.ai_socktype = SOCK_STREAM;
404 		proxyhints.ai_protocol = IPPROTO_TCP;
405 		if (nflag)
406 			proxyhints.ai_flags |= AI_NUMERICHOST;
407 	}
408 
409 	if (lflag) {
410 		int connfd;
411 		ret = 0;
412 
413 		if (family == AF_UNIX) {
414 			if (uflag)
415 				s = unix_bind(host);
416 			else
417 				s = unix_listen(host);
418 		}
419 
420 		/* Allow only one connection at a time, but stay alive. */
421 		for (;;) {
422 			if (family != AF_UNIX)
423 				s = local_listen(host, uport, hints);
424 			if (s < 0)
425 				err(1, NULL);
426 			/*
427 			 * For UDP and -k, don't connect the socket, let it
428 			 * receive datagrams from multiple socket pairs.
429 			 */
430 			if (uflag && kflag)
431 				readwrite(s);
432 			/*
433 			 * For UDP and not -k, we will use recvfrom() initially
434 			 * to wait for a caller, then use the regular functions
435 			 * to talk to the caller.
436 			 */
437 			else if (uflag && !kflag) {
438 				int rv, plen;
439 				char buf[16384];
440 				struct sockaddr_storage z;
441 
442 				len = sizeof(z);
443 				plen = 2048;
444 				rv = recvfrom(s, buf, plen, MSG_PEEK,
445 				    (struct sockaddr *)&z, &len);
446 				if (rv < 0)
447 					err(1, "recvfrom");
448 
449 				rv = connect(s, (struct sockaddr *)&z, len);
450 				if (rv < 0)
451 					err(1, "connect");
452 
453 				if (vflag)
454 					report_connect((struct sockaddr *)&z, len);
455 
456 				readwrite(s);
457 			} else {
458 				len = sizeof(cliaddr);
459 				connfd = accept(s, (struct sockaddr *)&cliaddr,
460 				    &len);
461 				if (connfd == -1) {
462 					/* For now, all errnos are fatal */
463 					err(1, "accept");
464 				}
465 				if (vflag)
466 					report_connect((struct sockaddr *)&cliaddr, len);
467 
468 				if (FreeBSD_Mflag)
469 					FreeBSD_stats_setup(connfd);
470 				readwrite(connfd);
471 				close(connfd);
472 			}
473 
474 			if (family != AF_UNIX)
475 				close(s);
476 			else if (uflag) {
477 				if (connect(s, NULL, 0) < 0)
478 					err(1, "connect");
479 			}
480 
481 			if (!kflag)
482 				break;
483 		}
484 	} else if (family == AF_UNIX) {
485 		ret = 0;
486 
487 		if ((s = unix_connect(host)) > 0 && !zflag) {
488 			readwrite(s);
489 			close(s);
490 		} else
491 			ret = 1;
492 
493 		if (uflag)
494 			unlink(unix_dg_tmp_socket);
495 		exit(ret);
496 
497 	} else {
498 		int i = 0;
499 
500 		/* Construct the portlist[] array. */
501 		build_ports(uport);
502 
503 		/* Cycle through portlist, connecting to each port. */
504 		for (i = 0; portlist[i] != NULL; i++) {
505 			if (s)
506 				close(s);
507 
508 			if (xflag)
509 				s = socks_connect(host, portlist[i], hints,
510 				    proxyhost, proxyport, proxyhints, socksv,
511 				    Pflag);
512 			else
513 				s = remote_connect(host, portlist[i], hints);
514 
515 			if (s < 0)
516 				continue;
517 
518 			ret = 0;
519 			if (vflag || zflag) {
520 				/* For UDP, make sure we are connected. */
521 				if (uflag) {
522 					if (udptest(s) == -1) {
523 						ret = 1;
524 						continue;
525 					}
526 				}
527 
528 				/* Don't look up port if -n. */
529 				if (nflag)
530 					sv = NULL;
531 				else {
532 					sv = getservbyport(
533 					    ntohs(atoi(portlist[i])),
534 					    uflag ? "udp" : "tcp");
535 				}
536 
537 				fprintf(stderr,
538 				    "Connection to %s %s port [%s/%s] "
539 				    "succeeded!\n", host, portlist[i],
540 				    uflag ? "udp" : "tcp",
541 				    sv ? sv->s_name : "*");
542 			}
543 			if (Fflag)
544 				fdpass(s);
545 			else if (!zflag)
546 				readwrite(s);
547 		}
548 	}
549 
550 	if (s)
551 		close(s);
552 
553 	exit(ret);
554 }
555 
556 /*
557  * unix_bind()
558  * Returns a unix socket bound to the given path
559  */
560 int
561 unix_bind(char *path)
562 {
563 	struct sockaddr_un sun;
564 	int s;
565 
566 	/* Create unix domain socket. */
567 	if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM,
568 	     0)) < 0)
569 		return (-1);
570 
571 	memset(&sun, 0, sizeof(struct sockaddr_un));
572 	sun.sun_family = AF_UNIX;
573 
574 	if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >=
575 	    sizeof(sun.sun_path)) {
576 		close(s);
577 		errno = ENAMETOOLONG;
578 		return (-1);
579 	}
580 
581 	if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
582 		close(s);
583 		return (-1);
584 	}
585 	return (s);
586 }
587 
588 /*
589  * unix_connect()
590  * Returns a socket connected to a local unix socket. Returns -1 on failure.
591  */
592 int
593 unix_connect(char *path)
594 {
595 	struct sockaddr_un sun;
596 	int s;
597 
598 	if (uflag) {
599 		if ((s = unix_bind(unix_dg_tmp_socket)) < 0)
600 			return (-1);
601 	} else {
602 		if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
603 			return (-1);
604 	}
605 	(void)fcntl(s, F_SETFD, FD_CLOEXEC);
606 
607 	memset(&sun, 0, sizeof(struct sockaddr_un));
608 	sun.sun_family = AF_UNIX;
609 
610 	if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >=
611 	    sizeof(sun.sun_path)) {
612 		close(s);
613 		errno = ENAMETOOLONG;
614 		return (-1);
615 	}
616 	if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
617 		close(s);
618 		return (-1);
619 	}
620 	return (s);
621 
622 }
623 
624 /*
625  * unix_listen()
626  * Create a unix domain socket, and listen on it.
627  */
628 int
629 unix_listen(char *path)
630 {
631 	int s;
632 	if ((s = unix_bind(path)) < 0)
633 		return (-1);
634 
635 	if (listen(s, 5) < 0) {
636 		close(s);
637 		return (-1);
638 	}
639 	return (s);
640 }
641 
642 /*
643  * remote_connect()
644  * Returns a socket connected to a remote host. Properly binds to a local
645  * port or source address if needed. Returns -1 on failure.
646  */
647 int
648 remote_connect(const char *host, const char *port, struct addrinfo hints)
649 {
650 	struct addrinfo *res, *res0;
651 	int s, error, on = 1;
652 
653 	if ((error = getaddrinfo(host, port, &hints, &res)))
654 		errx(1, "getaddrinfo: %s", gai_strerror(error));
655 
656 	res0 = res;
657 	do {
658 		if ((s = socket(res0->ai_family, res0->ai_socktype,
659 		    res0->ai_protocol)) < 0)
660 			continue;
661 
662 		if (rtableid >= 0 && (setsockopt(s, SOL_SOCKET, SO_SETFIB,
663 		    &rtableid, sizeof(rtableid)) == -1))
664 			err(1, "setsockopt SO_SETFIB");
665 
666 		/* Bind to a local port or source address if specified. */
667 		if (sflag || pflag) {
668 			struct addrinfo ahints, *ares;
669 
670 			/* try IP_BINDANY, but don't insist */
671 			setsockopt(s, IPPROTO_IP, IP_BINDANY, &on, sizeof(on));
672 			memset(&ahints, 0, sizeof(struct addrinfo));
673 			ahints.ai_family = res0->ai_family;
674 			ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM;
675 			ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP;
676 			ahints.ai_flags = AI_PASSIVE;
677 			if ((error = getaddrinfo(sflag, pflag, &ahints, &ares)))
678 				errx(1, "getaddrinfo: %s", gai_strerror(error));
679 
680 			if (bind(s, (struct sockaddr *)ares->ai_addr,
681 			    ares->ai_addrlen) < 0)
682 				err(1, "bind failed");
683 			freeaddrinfo(ares);
684 		}
685 
686 		set_common_sockopts(s, res0->ai_family);
687 
688 		if (timeout_connect(s, res0->ai_addr, res0->ai_addrlen) == 0)
689 			break;
690 		else if (vflag)
691 			warn("connect to %s port %s (%s) failed", host, port,
692 			    uflag ? "udp" : "tcp");
693 
694 		close(s);
695 		s = -1;
696 	} while ((res0 = res0->ai_next) != NULL);
697 
698 	freeaddrinfo(res);
699 
700 	return (s);
701 }
702 
703 int
704 timeout_connect(int s, const struct sockaddr *name, socklen_t namelen)
705 {
706 	struct pollfd pfd;
707 	socklen_t optlen;
708 	int flags, optval;
709 	int ret;
710 
711 	if (timeout != -1) {
712 		flags = fcntl(s, F_GETFL, 0);
713 		if (fcntl(s, F_SETFL, flags | O_NONBLOCK) == -1)
714 			err(1, "set non-blocking mode");
715 	}
716 
717 	if ((ret = connect(s, name, namelen)) != 0 && errno == EINPROGRESS) {
718 		pfd.fd = s;
719 		pfd.events = POLLOUT;
720 		if ((ret = poll(&pfd, 1, timeout)) == 1) {
721 			optlen = sizeof(optval);
722 			if ((ret = getsockopt(s, SOL_SOCKET, SO_ERROR,
723 			    &optval, &optlen)) == 0) {
724 				errno = optval;
725 				ret = optval == 0 ? 0 : -1;
726 			}
727 		} else if (ret == 0) {
728 			errno = ETIMEDOUT;
729 			ret = -1;
730 		} else
731 			err(1, "poll failed");
732 	}
733 
734 	if (timeout != -1 && fcntl(s, F_SETFL, flags) == -1)
735 		err(1, "restoring flags");
736 
737 	return (ret);
738 }
739 
740 /*
741  * local_listen()
742  * Returns a socket listening on a local port, binds to specified source
743  * address. Returns -1 on failure.
744  */
745 int
746 local_listen(char *host, char *port, struct addrinfo hints)
747 {
748 	struct addrinfo *res, *res0;
749 	int s, ret, x = 1;
750 	int error;
751 
752 	/* Allow nodename to be null. */
753 	hints.ai_flags |= AI_PASSIVE;
754 
755 	/*
756 	 * In the case of binding to a wildcard address
757 	 * default to binding to an ipv4 address.
758 	 */
759 	if (host == NULL && hints.ai_family == AF_UNSPEC)
760 		hints.ai_family = AF_INET;
761 
762 	if ((error = getaddrinfo(host, port, &hints, &res)))
763 		errx(1, "getaddrinfo: %s", gai_strerror(error));
764 
765 	res0 = res;
766 	do {
767 		if ((s = socket(res0->ai_family, res0->ai_socktype,
768 		    res0->ai_protocol)) < 0)
769 			continue;
770 
771 		if (rtableid >= 0 && (setsockopt(s, SOL_SOCKET, SO_SETFIB,
772 		    &rtableid, sizeof(rtableid)) == -1))
773 			err(1, "setsockopt SO_SETFIB");
774 
775 		ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x));
776 		if (ret == -1)
777 			err(1, NULL);
778 
779 		if (FreeBSD_Oflag) {
780 			if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT,
781 			    &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1)
782 				err(1, "disable TCP options");
783 		}
784 
785 		set_common_sockopts(s, res0->ai_family);
786 
787 		if (bind(s, (struct sockaddr *)res0->ai_addr,
788 		    res0->ai_addrlen) == 0)
789 			break;
790 
791 		close(s);
792 		s = -1;
793 	} while ((res0 = res0->ai_next) != NULL);
794 
795 	if (!uflag && s != -1) {
796 		if (listen(s, 1) < 0)
797 			err(1, "listen");
798 	}
799 
800 	freeaddrinfo(res);
801 
802 	return (s);
803 }
804 
805 /*
806  * readwrite()
807  * Loop that polls on the network file descriptor and stdin.
808  */
809 void
810 readwrite(int net_fd)
811 {
812 	struct pollfd pfd[4];
813 	int stdin_fd = STDIN_FILENO;
814 	int stdout_fd = STDOUT_FILENO;
815 	unsigned char netinbuf[BUFSIZE];
816 	size_t netinbufpos = 0;
817 	unsigned char stdinbuf[BUFSIZE];
818 	size_t stdinbufpos = 0;
819 	int n, num_fds;
820 	int stats_printed = 0;
821 	ssize_t ret;
822 
823 	/* don't read from stdin if requested */
824 	if (dflag)
825 		stdin_fd = -1;
826 
827 	/* stdin */
828 	pfd[POLL_STDIN].fd = stdin_fd;
829 	pfd[POLL_STDIN].events = POLLIN;
830 
831 	/* network out */
832 	pfd[POLL_NETOUT].fd = net_fd;
833 	pfd[POLL_NETOUT].events = 0;
834 
835 	/* network in */
836 	pfd[POLL_NETIN].fd = net_fd;
837 	pfd[POLL_NETIN].events = POLLIN;
838 
839 	/* stdout */
840 	pfd[POLL_STDOUT].fd = stdout_fd;
841 	pfd[POLL_STDOUT].events = 0;
842 
843 	while (1) {
844 		/* both inputs are gone, buffers are empty, we are done */
845 		if (pfd[POLL_STDIN].fd == -1 && pfd[POLL_NETIN].fd == -1
846 		    && stdinbufpos == 0 && netinbufpos == 0) {
847 			if (FreeBSD_Mflag && !stats_printed)
848 				FreeBSD_stats_print(net_fd);
849 			close(net_fd);
850 			return;
851 		}
852 		/* both outputs are gone, we can't continue */
853 		if (pfd[POLL_NETOUT].fd == -1 && pfd[POLL_STDOUT].fd == -1) {
854 			if (FreeBSD_Mflag && !stats_printed)
855 				FreeBSD_stats_print(net_fd);
856 			close(net_fd);
857 			return;
858 		}
859 		/* listen and net in gone, queues empty, done */
860 		if (lflag && pfd[POLL_NETIN].fd == -1
861 		    && stdinbufpos == 0 && netinbufpos == 0) {
862 			if (FreeBSD_Mflag && !stats_printed)
863 				FreeBSD_stats_print(net_fd);
864 			close(net_fd);
865 			return;
866 		}
867 
868 		/* help says -i is for "wait between lines sent". We read and
869 		 * write arbitrary amounts of data, and we don't want to start
870 		 * scanning for newlines, so this is as good as it gets */
871 		if (iflag)
872 			sleep(iflag);
873 
874 		/* poll */
875 		num_fds = poll(pfd, 4, timeout);
876 
877 		/* treat poll errors */
878 		if (num_fds == -1) {
879 			close(net_fd);
880 			err(1, "polling error");
881 		}
882 
883 		/* timeout happened */
884 		if (num_fds == 0) {
885 			if (FreeBSD_Mflag)
886 				FreeBSD_stats_print(net_fd);
887 			return;
888 		}
889 
890 		/* treat socket error conditions */
891 		for (n = 0; n < 4; n++) {
892 			if (pfd[n].revents & (POLLERR|POLLNVAL)) {
893 				pfd[n].fd = -1;
894 			}
895 		}
896 		/* reading is possible after HUP */
897 		if (pfd[POLL_STDIN].events & POLLIN &&
898 		    pfd[POLL_STDIN].revents & POLLHUP &&
899 		    ! (pfd[POLL_STDIN].revents & POLLIN))
900 				pfd[POLL_STDIN].fd = -1;
901 
902 		if (pfd[POLL_NETIN].events & POLLIN &&
903 		    pfd[POLL_NETIN].revents & POLLHUP &&
904 		    ! (pfd[POLL_NETIN].revents & POLLIN))
905 				pfd[POLL_NETIN].fd = -1;
906 
907 		if (pfd[POLL_NETOUT].revents & POLLHUP) {
908 			if (Nflag)
909 				shutdown(pfd[POLL_NETOUT].fd, SHUT_WR);
910 			pfd[POLL_NETOUT].fd = -1;
911 		}
912 		/* if HUP, stop watching stdout */
913 		if (pfd[POLL_STDOUT].revents & POLLHUP)
914 			pfd[POLL_STDOUT].fd = -1;
915 		/* if no net out, stop watching stdin */
916 		if (pfd[POLL_NETOUT].fd == -1)
917 			pfd[POLL_STDIN].fd = -1;
918 		/* if no stdout, stop watching net in */
919 		if (pfd[POLL_STDOUT].fd == -1) {
920 			if (pfd[POLL_NETIN].fd != -1)
921 				shutdown(pfd[POLL_NETIN].fd, SHUT_RD);
922 			pfd[POLL_NETIN].fd = -1;
923 		}
924 
925 		/* try to read from stdin */
926 		if (pfd[POLL_STDIN].revents & POLLIN && stdinbufpos < BUFSIZE) {
927 			ret = fillbuf(pfd[POLL_STDIN].fd, stdinbuf,
928 			    &stdinbufpos);
929 			/* error or eof on stdin - remove from pfd */
930 			if (ret == 0 || ret == -1)
931 				pfd[POLL_STDIN].fd = -1;
932 			/* read something - poll net out */
933 			if (stdinbufpos > 0)
934 				pfd[POLL_NETOUT].events = POLLOUT;
935 			/* filled buffer - remove self from polling */
936 			if (stdinbufpos == BUFSIZE)
937 				pfd[POLL_STDIN].events = 0;
938 		}
939 		/* try to write to network */
940 		if (pfd[POLL_NETOUT].revents & POLLOUT && stdinbufpos > 0) {
941 			ret = drainbuf(pfd[POLL_NETOUT].fd, stdinbuf,
942 			    &stdinbufpos);
943 			if (ret == -1)
944 				pfd[POLL_NETOUT].fd = -1;
945 			/* buffer empty - remove self from polling */
946 			if (stdinbufpos == 0)
947 				pfd[POLL_NETOUT].events = 0;
948 			/* buffer no longer full - poll stdin again */
949 			if (stdinbufpos < BUFSIZE)
950 				pfd[POLL_STDIN].events = POLLIN;
951 		}
952 		/* try to read from network */
953 		if (pfd[POLL_NETIN].revents & POLLIN && netinbufpos < BUFSIZE) {
954 			ret = fillbuf(pfd[POLL_NETIN].fd, netinbuf,
955 			    &netinbufpos);
956 			if (ret == -1)
957 				pfd[POLL_NETIN].fd = -1;
958 			/* eof on net in - remove from pfd */
959 			if (ret == 0) {
960 				shutdown(pfd[POLL_NETIN].fd, SHUT_RD);
961 				pfd[POLL_NETIN].fd = -1;
962 			}
963 			/* read something - poll stdout */
964 			if (netinbufpos > 0)
965 				pfd[POLL_STDOUT].events = POLLOUT;
966 			/* filled buffer - remove self from polling */
967 			if (netinbufpos == BUFSIZE)
968 				pfd[POLL_NETIN].events = 0;
969 			/* handle telnet */
970 			if (tflag)
971 				atelnet(pfd[POLL_NETIN].fd, netinbuf,
972 				    netinbufpos);
973 		}
974 		/* try to write to stdout */
975 		if (pfd[POLL_STDOUT].revents & POLLOUT && netinbufpos > 0) {
976 			ret = drainbuf(pfd[POLL_STDOUT].fd, netinbuf,
977 			    &netinbufpos);
978 			if (ret == -1)
979 				pfd[POLL_STDOUT].fd = -1;
980 			/* buffer empty - remove self from polling */
981 			if (netinbufpos == 0)
982 				pfd[POLL_STDOUT].events = 0;
983 			/* buffer no longer full - poll net in again */
984 			if (netinbufpos < BUFSIZE)
985 				pfd[POLL_NETIN].events = POLLIN;
986 		}
987 
988 		/* stdin gone and queue empty? */
989 		if (pfd[POLL_STDIN].fd == -1 && stdinbufpos == 0) {
990 			if (pfd[POLL_NETOUT].fd != -1 && Nflag) {
991 				if (FreeBSD_Mflag) {
992 					FreeBSD_stats_print(net_fd);
993 					stats_printed = 1;
994 				}
995 				shutdown(pfd[POLL_NETOUT].fd, SHUT_WR);
996 			}
997 			pfd[POLL_NETOUT].fd = -1;
998 		}
999 		/* net in gone and queue empty? */
1000 		if (pfd[POLL_NETIN].fd == -1 && netinbufpos == 0) {
1001 			pfd[POLL_STDOUT].fd = -1;
1002 		}
1003 	}
1004 }
1005 
1006 ssize_t
1007 drainbuf(int fd, unsigned char *buf, size_t *bufpos)
1008 {
1009 	ssize_t n;
1010 	ssize_t adjust;
1011 
1012 	n = write(fd, buf, *bufpos);
1013 	/* don't treat EAGAIN, EINTR as error */
1014 	if (n == -1 && (errno == EAGAIN || errno == EINTR))
1015 		n = -2;
1016 	if (n <= 0)
1017 		return n;
1018 	/* adjust buffer */
1019 	adjust = *bufpos - n;
1020 	if (adjust > 0)
1021 		memmove(buf, buf + n, adjust);
1022 	*bufpos -= n;
1023 	return n;
1024 }
1025 
1026 
1027 ssize_t
1028 fillbuf(int fd, unsigned char *buf, size_t *bufpos)
1029 {
1030 	size_t num = BUFSIZE - *bufpos;
1031 	ssize_t n;
1032 
1033 	n = read(fd, buf + *bufpos, num);
1034 	/* don't treat EAGAIN, EINTR as error */
1035 	if (n == -1 && (errno == EAGAIN || errno == EINTR))
1036 		n = -2;
1037 	if (n <= 0)
1038 		return n;
1039 	*bufpos += n;
1040 	return n;
1041 }
1042 
1043 /*
1044  * fdpass()
1045  * Pass the connected file descriptor to stdout and exit.
1046  */
1047 void
1048 fdpass(int nfd)
1049 {
1050 	struct msghdr mh;
1051 	union {
1052 		struct cmsghdr hdr;
1053 		char buf[CMSG_SPACE(sizeof(int))];
1054 	} cmsgbuf;
1055 	struct cmsghdr *cmsg;
1056 	struct iovec iov;
1057 	char c = '\0';
1058 	ssize_t r;
1059 	struct pollfd pfd;
1060 
1061 	/* Avoid obvious stupidity */
1062 	if (isatty(STDOUT_FILENO))
1063 		errx(1, "Cannot pass file descriptor to tty");
1064 
1065 	bzero(&mh, sizeof(mh));
1066 	bzero(&cmsgbuf, sizeof(cmsgbuf));
1067 	bzero(&iov, sizeof(iov));
1068 
1069 	mh.msg_control = (caddr_t)&cmsgbuf.buf;
1070 	mh.msg_controllen = sizeof(cmsgbuf.buf);
1071 	cmsg = CMSG_FIRSTHDR(&mh);
1072 	cmsg->cmsg_len = CMSG_LEN(sizeof(int));
1073 	cmsg->cmsg_level = SOL_SOCKET;
1074 	cmsg->cmsg_type = SCM_RIGHTS;
1075 	*(int *)CMSG_DATA(cmsg) = nfd;
1076 
1077 	iov.iov_base = &c;
1078 	iov.iov_len = 1;
1079 	mh.msg_iov = &iov;
1080 	mh.msg_iovlen = 1;
1081 
1082 	bzero(&pfd, sizeof(pfd));
1083 	pfd.fd = STDOUT_FILENO;
1084 	pfd.events = POLLOUT;
1085 	for (;;) {
1086 		r = sendmsg(STDOUT_FILENO, &mh, 0);
1087 		if (r == -1) {
1088 			if (errno == EAGAIN || errno == EINTR) {
1089 				if (poll(&pfd, 1, -1) == -1)
1090 					err(1, "poll");
1091 				continue;
1092 			}
1093 			err(1, "sendmsg");
1094 		} else if (r != 1)
1095 			errx(1, "sendmsg: unexpected return value %zd", r);
1096 		else
1097 			break;
1098 	}
1099 	exit(0);
1100 }
1101 
1102 /* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */
1103 void
1104 atelnet(int nfd, unsigned char *buf, unsigned int size)
1105 {
1106 	unsigned char *p, *end;
1107 	unsigned char obuf[4];
1108 
1109 	if (size < 3)
1110 		return;
1111 	end = buf + size - 2;
1112 
1113 	for (p = buf; p < end; p++) {
1114 		if (*p != IAC)
1115 			continue;
1116 
1117 		obuf[0] = IAC;
1118 		p++;
1119 		if ((*p == WILL) || (*p == WONT))
1120 			obuf[1] = DONT;
1121 		else if ((*p == DO) || (*p == DONT))
1122 			obuf[1] = WONT;
1123 		else
1124 			continue;
1125 
1126 		p++;
1127 		obuf[2] = *p;
1128 		if (atomicio(vwrite, nfd, obuf, 3) != 3)
1129 			warn("Write Error!");
1130 	}
1131 }
1132 
1133 /*
1134  * build_ports()
1135  * Build an array of ports in portlist[], listing each port
1136  * that we should try to connect to.
1137  */
1138 void
1139 build_ports(char *p)
1140 {
1141 	const char *errstr;
1142 	char *n;
1143 	int hi, lo, cp;
1144 	int x = 0;
1145 
1146 	if ((n = strchr(p, '-')) != NULL) {
1147 		*n = '\0';
1148 		n++;
1149 
1150 		/* Make sure the ports are in order: lowest->highest. */
1151 		hi = strtonum(n, 1, PORT_MAX, &errstr);
1152 		if (errstr)
1153 			errx(1, "port number %s: %s", errstr, n);
1154 		lo = strtonum(p, 1, PORT_MAX, &errstr);
1155 		if (errstr)
1156 			errx(1, "port number %s: %s", errstr, p);
1157 
1158 		if (lo > hi) {
1159 			cp = hi;
1160 			hi = lo;
1161 			lo = cp;
1162 		}
1163 
1164 		/* Load ports sequentially. */
1165 		for (cp = lo; cp <= hi; cp++) {
1166 			portlist[x] = calloc(1, PORT_MAX_LEN);
1167 			if (portlist[x] == NULL)
1168 				err(1, NULL);
1169 			snprintf(portlist[x], PORT_MAX_LEN, "%d", cp);
1170 			x++;
1171 		}
1172 
1173 		/* Randomly swap ports. */
1174 		if (rflag) {
1175 			int y;
1176 			char *c;
1177 
1178 			for (x = 0; x <= (hi - lo); x++) {
1179 				y = (arc4random() & 0xFFFF) % (hi - lo);
1180 				c = portlist[x];
1181 				portlist[x] = portlist[y];
1182 				portlist[y] = c;
1183 			}
1184 		}
1185 	} else {
1186 		hi = strtonum(p, 1, PORT_MAX, &errstr);
1187 		if (errstr)
1188 			errx(1, "port number %s: %s", errstr, p);
1189 		portlist[0] = strdup(p);
1190 		if (portlist[0] == NULL)
1191 			err(1, NULL);
1192 	}
1193 }
1194 
1195 /*
1196  * udptest()
1197  * Do a few writes to see if the UDP port is there.
1198  * Fails once PF state table is full.
1199  */
1200 int
1201 udptest(int s)
1202 {
1203 	int i, ret;
1204 
1205 	for (i = 0; i <= 3; i++) {
1206 		if (write(s, "X", 1) == 1)
1207 			ret = 1;
1208 		else
1209 			ret = -1;
1210 	}
1211 	return (ret);
1212 }
1213 
1214 void
1215 FreeBSD_stats_setup(int s)
1216 {
1217 
1218 	if (setsockopt(s, IPPROTO_TCP, TCP_STATS,
1219 	    &FreeBSD_Mflag, sizeof(FreeBSD_Mflag)) == -1) {
1220 		if (errno == EOPNOTSUPP) {
1221 			warnx("getsockopt(TCP_STATS) failed; "
1222 			    "kernel built without \"options STATS\"?");
1223 		}
1224 		err(1, "enable TCP_STATS gathering");
1225 	}
1226 }
1227 
1228 void
1229 FreeBSD_stats_print(int s)
1230 {
1231 #ifdef WITH_STATS
1232 	struct statsblob *statsb;
1233 	struct sbuf *sb;
1234 	socklen_t sockoptlen;
1235 	int error;
1236 
1237 	/*
1238 	 * This usleep is a workaround for TCP_STATS reporting
1239 	 * incorrect values for TXPB.
1240 	 */
1241 	usleep(100000);
1242 
1243 	sockoptlen = 2048;
1244 	statsb = malloc(sockoptlen);
1245 	if (statsb == NULL)
1246 		err(1, "malloc");
1247 	error = getsockopt(s, IPPROTO_TCP, TCP_STATS, statsb, &sockoptlen);
1248 	if (error != 0) {
1249 		if (errno == EOVERFLOW && statsb->cursz > sockoptlen) {
1250 			/* Retry with a larger size. */
1251 			sockoptlen = statsb->cursz;
1252 			statsb = realloc(statsb, sockoptlen);
1253 			if (statsb == NULL)
1254 				err(1, "realloc");
1255 			error = getsockopt(s, IPPROTO_TCP, TCP_STATS,
1256 			    statsb, &sockoptlen);
1257 		}
1258 		if (error != 0)
1259 			err(1, "getsockopt");
1260 	}
1261 
1262 	sb = sbuf_new_auto();
1263 	error = stats_blob_tostr(statsb, sb, SB_STRFMT_JSON, SB_TOSTR_META);
1264 	if (error != 0)
1265 		errc(1, error, "stats_blob_tostr");
1266 
1267 	error = sbuf_finish(sb);
1268 	if (error != 0)
1269 		err(1, "sbuf_finish");
1270 
1271 	fprintf(stderr, "%s\n", sbuf_data(sb));
1272 #endif
1273 }
1274 
1275 void
1276 set_common_sockopts(int s, int af)
1277 {
1278 	int x = 1;
1279 
1280 	if (Sflag) {
1281 		if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG,
1282 			&x, sizeof(x)) == -1)
1283 			err(1, NULL);
1284 	}
1285 	if (Dflag) {
1286 		if (setsockopt(s, SOL_SOCKET, SO_DEBUG,
1287 			&x, sizeof(x)) == -1)
1288 			err(1, NULL);
1289 	}
1290 	if (Tflag != -1) {
1291 		int proto, option;
1292 
1293 		if (af == AF_INET6) {
1294 			proto = IPPROTO_IPV6;
1295 			option = IPV6_TCLASS;
1296 		} else {
1297 			proto = IPPROTO_IP;
1298 			option = IP_TOS;
1299 		}
1300 
1301 		if (setsockopt(s, proto, option, &Tflag, sizeof(Tflag)) == -1)
1302 			err(1, "set IP ToS");
1303 	}
1304 	if (Iflag) {
1305 		if (setsockopt(s, SOL_SOCKET, SO_RCVBUF,
1306 		    &Iflag, sizeof(Iflag)) == -1)
1307 			err(1, "set TCP receive buffer size");
1308 	}
1309 	if (Oflag) {
1310 		if (setsockopt(s, SOL_SOCKET, SO_SNDBUF,
1311 		    &Oflag, sizeof(Oflag)) == -1)
1312 			err(1, "set TCP send buffer size");
1313 	}
1314 	if (FreeBSD_Oflag) {
1315 		if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT,
1316 		    &FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1)
1317 			err(1, "disable TCP options");
1318 	}
1319 	if (FreeBSD_Mflag)
1320 		FreeBSD_stats_setup(s);
1321 #ifdef IPSEC
1322 	if (ipsec_policy[0] != NULL)
1323 		add_ipsec_policy(s, af, ipsec_policy[0]);
1324 	if (ipsec_policy[1] != NULL)
1325 		add_ipsec_policy(s, af, ipsec_policy[1]);
1326 #endif
1327 }
1328 
1329 int
1330 map_tos(char *s, int *val)
1331 {
1332 	/* DiffServ Codepoints and other TOS mappings */
1333 	const struct toskeywords {
1334 		const char	*keyword;
1335 		int		 val;
1336 	} *t, toskeywords[] = {
1337 		{ "af11",		IPTOS_DSCP_AF11 },
1338 		{ "af12",		IPTOS_DSCP_AF12 },
1339 		{ "af13",		IPTOS_DSCP_AF13 },
1340 		{ "af21",		IPTOS_DSCP_AF21 },
1341 		{ "af22",		IPTOS_DSCP_AF22 },
1342 		{ "af23",		IPTOS_DSCP_AF23 },
1343 		{ "af31",		IPTOS_DSCP_AF31 },
1344 		{ "af32",		IPTOS_DSCP_AF32 },
1345 		{ "af33",		IPTOS_DSCP_AF33 },
1346 		{ "af41",		IPTOS_DSCP_AF41 },
1347 		{ "af42",		IPTOS_DSCP_AF42 },
1348 		{ "af43",		IPTOS_DSCP_AF43 },
1349 		{ "critical",		IPTOS_PREC_CRITIC_ECP },
1350 		{ "cs0",		IPTOS_DSCP_CS0 },
1351 		{ "cs1",		IPTOS_DSCP_CS1 },
1352 		{ "cs2",		IPTOS_DSCP_CS2 },
1353 		{ "cs3",		IPTOS_DSCP_CS3 },
1354 		{ "cs4",		IPTOS_DSCP_CS4 },
1355 		{ "cs5",		IPTOS_DSCP_CS5 },
1356 		{ "cs6",		IPTOS_DSCP_CS6 },
1357 		{ "cs7",		IPTOS_DSCP_CS7 },
1358 		{ "ef",			IPTOS_DSCP_EF },
1359 		{ "inetcontrol",	IPTOS_PREC_INTERNETCONTROL },
1360 		{ "lowdelay",		IPTOS_LOWDELAY },
1361 		{ "netcontrol",		IPTOS_PREC_NETCONTROL },
1362 		{ "reliability",	IPTOS_RELIABILITY },
1363 		{ "throughput",		IPTOS_THROUGHPUT },
1364 		{ NULL, 		-1 },
1365 	};
1366 
1367 	for (t = toskeywords; t->keyword != NULL; t++) {
1368 		if (strcmp(s, t->keyword) == 0) {
1369 			*val = t->val;
1370 			return (1);
1371 		}
1372 	}
1373 
1374 	return (0);
1375 }
1376 
1377 void
1378 report_connect(const struct sockaddr *sa, socklen_t salen)
1379 {
1380 	char remote_host[NI_MAXHOST];
1381 	char remote_port[NI_MAXSERV];
1382 	int herr;
1383 	int flags = NI_NUMERICSERV;
1384 
1385 	if (nflag)
1386 		flags |= NI_NUMERICHOST;
1387 
1388 	if ((herr = getnameinfo(sa, salen,
1389 	    remote_host, sizeof(remote_host),
1390 	    remote_port, sizeof(remote_port),
1391 	    flags)) != 0) {
1392 		if (herr == EAI_SYSTEM)
1393 			err(1, "getnameinfo");
1394 		else
1395 			errx(1, "getnameinfo: %s", gai_strerror(herr));
1396 	}
1397 
1398 	fprintf(stderr,
1399 	    "Connection from %s %s "
1400 	    "received!\n", remote_host, remote_port);
1401 }
1402 
1403 void
1404 help(void)
1405 {
1406 	usage(0);
1407 	fprintf(stderr, "\tCommand Summary:\n\
1408 	\t-4		Use IPv4\n\
1409 	\t-6		Use IPv6\n\
1410 	\t-D		Enable the debug socket option\n\
1411 	\t-d		Detach from stdin\n");
1412 #ifdef IPSEC
1413 	fprintf(stderr, "\
1414 	\t-E		Use IPsec ESP\n\
1415 	\t-e policy	Use specified IPsec policy\n");
1416 #endif
1417 	fprintf(stderr, "\
1418 	\t-F		Pass socket fd\n\
1419 	\t-h		This help text\n\
1420 	\t-I length	TCP receive buffer length\n\
1421 	\t-i secs\t	Delay interval for lines sent, ports scanned\n\
1422 	\t-k		Keep inbound sockets open for multiple connects\n\
1423 	\t-l		Listen mode, for inbound connects\n\
1424 	\t-N		Shutdown the network socket after EOF on stdin\n\
1425 	\t-n		Suppress name/port resolutions\n\
1426 	\t--no-tcpopt	Disable TCP options\n\
1427 	\t-O length	TCP send buffer length\n\
1428 	\t-P proxyuser\tUsername for proxy authentication\n\
1429 	\t-p port\t	Specify local port for remote connects\n\
1430 	\t-r		Randomize remote ports\n\
1431 	\t-S		Enable the TCP MD5 signature option\n\
1432 	\t-s addr\t	Local source address\n\
1433 	\t-T toskeyword\tSet IP Type of Service\n\
1434 	\t-t		Answer TELNET negotiation\n\
1435 	\t-U		Use UNIX domain socket\n\
1436 	\t-u		UDP mode\n\
1437 	\t-V rtable	Specify alternate routing table\n\
1438 	\t-v		Verbose\n\
1439 	\t-w secs\t	Timeout for connects and final net reads\n\
1440 	\t-X proto	Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\
1441 	\t-x addr[:port]\tSpecify proxy address and port\n\
1442 	\t-z		Zero-I/O mode [used for scanning]\n\
1443 	Port numbers can be individual or ranges: lo-hi [inclusive]\n");
1444 #ifdef IPSEC
1445 	fprintf(stderr, "See ipsec_set_policy(3) for -e argument format\n");
1446 #endif
1447 	exit(1);
1448 }
1449 
1450 #ifdef IPSEC
1451 void
1452 add_ipsec_policy(int s, int af, char *policy)
1453 {
1454 	char *raw;
1455 	int e;
1456 
1457 	raw = ipsec_set_policy(policy, strlen(policy));
1458 	if (raw == NULL)
1459 		errx(1, "ipsec_set_policy `%s': %s", policy,
1460 		     ipsec_strerror());
1461 	if (af == AF_INET)
1462 		e = setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, raw,
1463 		    ipsec_get_policylen(raw));
1464 	if (af == AF_INET6)
1465 		e = setsockopt(s, IPPROTO_IPV6, IPV6_IPSEC_POLICY, raw,
1466 		    ipsec_get_policylen(raw));
1467 	if (e < 0)
1468 		err(1, "ipsec policy cannot be configured");
1469 	free(raw);
1470 	if (vflag)
1471 		fprintf(stderr, "ipsec policy configured: `%s'\n", policy);
1472 	return;
1473 }
1474 #endif /* IPSEC */
1475 
1476 void
1477 usage(int ret)
1478 {
1479 	fprintf(stderr,
1480 #ifdef IPSEC
1481 	    "usage: nc [-46DdEFhklNnrStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n"
1482 #else
1483 	    "usage: nc [-46DdFhklNnrStUuvz] [-I length] [-i interval] [-O length]\n"
1484 #endif
1485 	    "\t  [-P proxy_username] [-p source_port] [-s source] [-T ToS]\n"
1486 	    "\t  [-V rtable] [-w timeout] [-X proxy_protocol]\n"
1487 	    "\t  [-x proxy_address[:port]] [destination] [port]\n");
1488 	if (ret)
1489 		exit(1);
1490 }
1491