xref: /freebsd/crypto/openssh/ssh-keyscan.c (revision f388f5ef2694c14a9c45d0b328d12bdc2c2e6d83) 
1 /*
2  * Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>.
3  *
4  * Modification and redistribution in source and binary forms is
5  * permitted provided that due credit is given to the author and the
6  * OpenBSD project by leaving this copyright notice intact.
7  */
8 
9 #include "includes.h"
10 RCSID("$OpenBSD: ssh-keyscan.c,v 1.40 2002/07/06 17:47:58 stevesk Exp $");
11 RCSID("$FreeBSD$");
12 
13 #include "openbsd-compat/sys-queue.h"
14 
15 #include <openssl/bn.h>
16 
17 #include <setjmp.h>
18 #include "xmalloc.h"
19 #include "ssh.h"
20 #include "ssh1.h"
21 #include "key.h"
22 #include "kex.h"
23 #include "compat.h"
24 #include "myproposal.h"
25 #include "packet.h"
26 #include "dispatch.h"
27 #include "buffer.h"
28 #include "bufaux.h"
29 #include "log.h"
30 #include "atomicio.h"
31 #include "misc.h"
32 
33 /* Flag indicating whether IPv4 or IPv6.  This can be set on the command line.
34    Default value is AF_UNSPEC means both IPv4 and IPv6. */
35 #ifdef IPV4_DEFAULT
36 int IPv4or6 = AF_INET;
37 #else
38 int IPv4or6 = AF_UNSPEC;
39 #endif
40 
41 int ssh_port = SSH_DEFAULT_PORT;
42 
43 #define KT_RSA1	1
44 #define KT_DSA	2
45 #define KT_RSA	4
46 
47 int get_keytypes = KT_RSA1;	/* Get only RSA1 keys by default */
48 
49 #define MAXMAXFD 256
50 
51 /* The number of seconds after which to give up on a TCP connection */
52 int timeout = 5;
53 
54 int maxfd;
55 #define MAXCON (maxfd - 10)
56 
57 #ifdef HAVE___PROGNAME
58 extern char *__progname;
59 #else
60 char *__progname;
61 #endif
62 fd_set *read_wait;
63 size_t read_wait_size;
64 int ncon;
65 int nonfatal_fatal = 0;
66 jmp_buf kexjmp;
67 Key *kexjmp_key;
68 
69 /*
70  * Keep a connection structure for each file descriptor.  The state
71  * associated with file descriptor n is held in fdcon[n].
72  */
73 typedef struct Connection {
74 	u_char c_status;	/* State of connection on this file desc. */
75 #define CS_UNUSED 0		/* File descriptor unused */
76 #define CS_CON 1		/* Waiting to connect/read greeting */
77 #define CS_SIZE 2		/* Waiting to read initial packet size */
78 #define CS_KEYS 3		/* Waiting to read public key packet */
79 	int c_fd;		/* Quick lookup: c->c_fd == c - fdcon */
80 	int c_plen;		/* Packet length field for ssh packet */
81 	int c_len;		/* Total bytes which must be read. */
82 	int c_off;		/* Length of data read so far. */
83 	int c_keytype;		/* Only one of KT_RSA1, KT_DSA, or KT_RSA */
84 	char *c_namebase;	/* Address to free for c_name and c_namelist */
85 	char *c_name;		/* Hostname of connection for errors */
86 	char *c_namelist;	/* Pointer to other possible addresses */
87 	char *c_output_name;	/* Hostname of connection for output */
88 	char *c_data;		/* Data read from this fd */
89 	Kex *c_kex;		/* The key-exchange struct for ssh2 */
90 	struct timeval c_tv;	/* Time at which connection gets aborted */
91 	TAILQ_ENTRY(Connection) c_link;	/* List of connections in timeout order. */
92 } con;
93 
94 TAILQ_HEAD(conlist, Connection) tq;	/* Timeout Queue */
95 con *fdcon;
96 
97 /*
98  *  This is just a wrapper around fgets() to make it usable.
99  */
100 
101 /* Stress-test.  Increase this later. */
102 #define LINEBUF_SIZE 16
103 
104 typedef struct {
105 	char *buf;
106 	u_int size;
107 	int lineno;
108 	const char *filename;
109 	FILE *stream;
110 	void (*errfun) (const char *,...);
111 } Linebuf;
112 
113 static Linebuf *
114 Linebuf_alloc(const char *filename, void (*errfun) (const char *,...))
115 {
116 	Linebuf *lb;
117 
118 	if (!(lb = malloc(sizeof(*lb)))) {
119 		if (errfun)
120 			(*errfun) ("linebuf (%s): malloc failed\n",
121 			    filename ? filename : "(stdin)");
122 		return (NULL);
123 	}
124 	if (filename) {
125 		lb->filename = filename;
126 		if (!(lb->stream = fopen(filename, "r"))) {
127 			xfree(lb);
128 			if (errfun)
129 				(*errfun) ("%s: %s\n", filename, strerror(errno));
130 			return (NULL);
131 		}
132 	} else {
133 		lb->filename = "(stdin)";
134 		lb->stream = stdin;
135 	}
136 
137 	if (!(lb->buf = malloc(lb->size = LINEBUF_SIZE))) {
138 		if (errfun)
139 			(*errfun) ("linebuf (%s): malloc failed\n", lb->filename);
140 		xfree(lb);
141 		return (NULL);
142 	}
143 	lb->errfun = errfun;
144 	lb->lineno = 0;
145 	return (lb);
146 }
147 
148 static void
149 Linebuf_free(Linebuf * lb)
150 {
151 	fclose(lb->stream);
152 	xfree(lb->buf);
153 	xfree(lb);
154 }
155 
156 #if 0
157 static void
158 Linebuf_restart(Linebuf * lb)
159 {
160 	clearerr(lb->stream);
161 	rewind(lb->stream);
162 	lb->lineno = 0;
163 }
164 
165 static int
166 Linebuf_lineno(Linebuf * lb)
167 {
168 	return (lb->lineno);
169 }
170 #endif
171 
172 static char *
173 Linebuf_getline(Linebuf * lb)
174 {
175 	int n = 0;
176 	void *p;
177 
178 	lb->lineno++;
179 	for (;;) {
180 		/* Read a line */
181 		if (!fgets(&lb->buf[n], lb->size - n, lb->stream)) {
182 			if (ferror(lb->stream) && lb->errfun)
183 				(*lb->errfun)("%s: %s\n", lb->filename,
184 				    strerror(errno));
185 			return (NULL);
186 		}
187 		n = strlen(lb->buf);
188 
189 		/* Return it or an error if it fits */
190 		if (n > 0 && lb->buf[n - 1] == '\n') {
191 			lb->buf[n - 1] = '\0';
192 			return (lb->buf);
193 		}
194 		if (n != lb->size - 1) {
195 			if (lb->errfun)
196 				(*lb->errfun)("%s: skipping incomplete last line\n",
197 				    lb->filename);
198 			return (NULL);
199 		}
200 		/* Double the buffer if we need more space */
201 		lb->size *= 2;
202 		if ((p = realloc(lb->buf, lb->size)) == NULL) {
203 			lb->size /= 2;
204 			if (lb->errfun)
205 				(*lb->errfun)("linebuf (%s): realloc failed\n",
206 				    lb->filename);
207 			return (NULL);
208 		}
209 		lb->buf = p;
210 	}
211 }
212 
213 static int
214 fdlim_get(int hard)
215 {
216 #if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
217 	struct rlimit rlfd;
218 
219 	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
220 		return (-1);
221 	if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY)
222 		return 10000;
223 	else
224 		return hard ? rlfd.rlim_max : rlfd.rlim_cur;
225 #elif defined (HAVE_SYSCONF)
226 	return sysconf (_SC_OPEN_MAX);
227 #else
228 	return 10000;
229 #endif
230 }
231 
232 static int
233 fdlim_set(int lim)
234 {
235 #if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
236 	struct rlimit rlfd;
237 #endif
238 
239 	if (lim <= 0)
240 		return (-1);
241 #if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
242 	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
243 		return (-1);
244 	rlfd.rlim_cur = lim;
245 	if (setrlimit(RLIMIT_NOFILE, &rlfd) < 0)
246 		return (-1);
247 #elif defined (HAVE_SETDTABLESIZE)
248 	setdtablesize(lim);
249 #endif
250 	return (0);
251 }
252 
253 /*
254  * This is an strsep function that returns a null field for adjacent
255  * separators.  This is the same as the 4.4BSD strsep, but different from the
256  * one in the GNU libc.
257  */
258 static char *
259 xstrsep(char **str, const char *delim)
260 {
261 	char *s, *e;
262 
263 	if (!**str)
264 		return (NULL);
265 
266 	s = *str;
267 	e = s + strcspn(s, delim);
268 
269 	if (*e != '\0')
270 		*e++ = '\0';
271 	*str = e;
272 
273 	return (s);
274 }
275 
276 /*
277  * Get the next non-null token (like GNU strsep).  Strsep() will return a
278  * null token for two adjacent separators, so we may have to loop.
279  */
280 static char *
281 strnnsep(char **stringp, char *delim)
282 {
283 	char *tok;
284 
285 	do {
286 		tok = xstrsep(stringp, delim);
287 	} while (tok && *tok == '\0');
288 	return (tok);
289 }
290 
291 static Key *
292 keygrab_ssh1(con *c)
293 {
294 	static Key *rsa;
295 	static Buffer msg;
296 
297 	if (rsa == NULL) {
298 		buffer_init(&msg);
299 		rsa = key_new(KEY_RSA1);
300 	}
301 	buffer_append(&msg, c->c_data, c->c_plen);
302 	buffer_consume(&msg, 8 - (c->c_plen & 7));	/* padding */
303 	if (buffer_get_char(&msg) != (int) SSH_SMSG_PUBLIC_KEY) {
304 		error("%s: invalid packet type", c->c_name);
305 		buffer_clear(&msg);
306 		return NULL;
307 	}
308 	buffer_consume(&msg, 8);		/* cookie */
309 
310 	/* server key */
311 	(void) buffer_get_int(&msg);
312 	buffer_get_bignum(&msg, rsa->rsa->e);
313 	buffer_get_bignum(&msg, rsa->rsa->n);
314 
315 	/* host key */
316 	(void) buffer_get_int(&msg);
317 	buffer_get_bignum(&msg, rsa->rsa->e);
318 	buffer_get_bignum(&msg, rsa->rsa->n);
319 
320 	buffer_clear(&msg);
321 
322 	return (rsa);
323 }
324 
325 static int
326 hostjump(Key *hostkey)
327 {
328 	kexjmp_key = hostkey;
329 	longjmp(kexjmp, 1);
330 }
331 
332 static int
333 ssh2_capable(int remote_major, int remote_minor)
334 {
335 	switch (remote_major) {
336 	case 1:
337 		if (remote_minor == 99)
338 			return 1;
339 		break;
340 	case 2:
341 		return 1;
342 	default:
343 		break;
344 	}
345 	return 0;
346 }
347 
348 static Key *
349 keygrab_ssh2(con *c)
350 {
351 	int j;
352 
353 	packet_set_connection(c->c_fd, c->c_fd);
354 	enable_compat20();
355 	myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = c->c_keytype == KT_DSA?
356 	    "ssh-dss": "ssh-rsa";
357 	c->c_kex = kex_setup(myproposal);
358 	c->c_kex->verify_host_key = hostjump;
359 
360 	if (!(j = setjmp(kexjmp))) {
361 		nonfatal_fatal = 1;
362 		dispatch_run(DISPATCH_BLOCK, &c->c_kex->done, c->c_kex);
363 		fprintf(stderr, "Impossible! dispatch_run() returned!\n");
364 		exit(1);
365 	}
366 	nonfatal_fatal = 0;
367 	xfree(c->c_kex);
368 	c->c_kex = NULL;
369 	packet_close();
370 
371 	return j < 0? NULL : kexjmp_key;
372 }
373 
374 static void
375 keyprint(con *c, Key *key)
376 {
377 	if (!key)
378 		return;
379 
380 	fprintf(stdout, "%s ", c->c_output_name ? c->c_output_name : c->c_name);
381 	key_write(key, stdout);
382 	fputs("\n", stdout);
383 }
384 
385 static int
386 tcpconnect(char *host)
387 {
388 	struct addrinfo hints, *ai, *aitop;
389 	char strport[NI_MAXSERV];
390 	int gaierr, s = -1;
391 
392 	snprintf(strport, sizeof strport, "%d", ssh_port);
393 	memset(&hints, 0, sizeof(hints));
394 	hints.ai_family = IPv4or6;
395 	hints.ai_socktype = SOCK_STREAM;
396 	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
397 		fatal("getaddrinfo %s: %s", host, gai_strerror(gaierr));
398 	for (ai = aitop; ai; ai = ai->ai_next) {
399 		s = socket(ai->ai_family, SOCK_STREAM, 0);
400 		if (s < 0) {
401 			error("socket: %s", strerror(errno));
402 			continue;
403 		}
404 		if (fcntl(s, F_SETFL, O_NONBLOCK) < 0)
405 			fatal("F_SETFL: %s", strerror(errno));
406 		if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0 &&
407 		    errno != EINPROGRESS)
408 			error("connect (`%s'): %s", host, strerror(errno));
409 		else
410 			break;
411 		close(s);
412 		s = -1;
413 	}
414 	freeaddrinfo(aitop);
415 	return s;
416 }
417 
418 static int
419 conalloc(char *iname, char *oname, int keytype)
420 {
421 	char *namebase, *name, *namelist;
422 	int s;
423 
424 	namebase = namelist = xstrdup(iname);
425 
426 	do {
427 		name = xstrsep(&namelist, ",");
428 		if (!name) {
429 			xfree(namebase);
430 			return (-1);
431 		}
432 	} while ((s = tcpconnect(name)) < 0);
433 
434 	if (s >= maxfd)
435 		fatal("conalloc: fdno %d too high", s);
436 	if (fdcon[s].c_status)
437 		fatal("conalloc: attempt to reuse fdno %d", s);
438 
439 	fdcon[s].c_fd = s;
440 	fdcon[s].c_status = CS_CON;
441 	fdcon[s].c_namebase = namebase;
442 	fdcon[s].c_name = name;
443 	fdcon[s].c_namelist = namelist;
444 	fdcon[s].c_output_name = xstrdup(oname);
445 	fdcon[s].c_data = (char *) &fdcon[s].c_plen;
446 	fdcon[s].c_len = 4;
447 	fdcon[s].c_off = 0;
448 	fdcon[s].c_keytype = keytype;
449 	gettimeofday(&fdcon[s].c_tv, NULL);
450 	fdcon[s].c_tv.tv_sec += timeout;
451 	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
452 	FD_SET(s, read_wait);
453 	ncon++;
454 	return (s);
455 }
456 
457 static void
458 confree(int s)
459 {
460 	if (s >= maxfd || fdcon[s].c_status == CS_UNUSED)
461 		fatal("confree: attempt to free bad fdno %d", s);
462 	close(s);
463 	xfree(fdcon[s].c_namebase);
464 	xfree(fdcon[s].c_output_name);
465 	if (fdcon[s].c_status == CS_KEYS)
466 		xfree(fdcon[s].c_data);
467 	fdcon[s].c_status = CS_UNUSED;
468 	fdcon[s].c_keytype = 0;
469 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
470 	FD_CLR(s, read_wait);
471 	ncon--;
472 }
473 
474 static void
475 contouch(int s)
476 {
477 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
478 	gettimeofday(&fdcon[s].c_tv, NULL);
479 	fdcon[s].c_tv.tv_sec += timeout;
480 	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
481 }
482 
483 static int
484 conrecycle(int s)
485 {
486 	con *c = &fdcon[s];
487 	int ret;
488 
489 	ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
490 	confree(s);
491 	return (ret);
492 }
493 
494 static void
495 congreet(int s)
496 {
497 	int remote_major, remote_minor, n = 0;
498 	char buf[256], *cp;
499 	char remote_version[sizeof buf];
500 	size_t bufsiz;
501 	con *c = &fdcon[s];
502 
503 	bufsiz = sizeof(buf);
504 	cp = buf;
505 	while (bufsiz-- && (n = read(s, cp, 1)) == 1 && *cp != '\n') {
506 		if (*cp == '\r')
507 			*cp = '\n';
508 		cp++;
509 	}
510 	if (n < 0) {
511 		if (errno != ECONNREFUSED)
512 			error("read (%s): %s", c->c_name, strerror(errno));
513 		conrecycle(s);
514 		return;
515 	}
516 	if (n == 0) {
517 		error("%s: Connection closed by remote host", c->c_name);
518 		conrecycle(s);
519 		return;
520 	}
521 	if (*cp != '\n' && *cp != '\r') {
522 		error("%s: bad greeting", c->c_name);
523 		confree(s);
524 		return;
525 	}
526 	*cp = '\0';
527 	if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
528 	    &remote_major, &remote_minor, remote_version) == 3)
529 		compat_datafellows(remote_version);
530 	else
531 		datafellows = 0;
532 	if (c->c_keytype != KT_RSA1) {
533 		if (!ssh2_capable(remote_major, remote_minor)) {
534 			debug("%s doesn't support ssh2", c->c_name);
535 			confree(s);
536 			return;
537 		}
538 	} else if (remote_major != 1) {
539 		debug("%s doesn't support ssh1", c->c_name);
540 		confree(s);
541 		return;
542 	}
543 	fprintf(stderr, "# %s %s\n", c->c_name, chop(buf));
544 	n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
545 	    c->c_keytype == KT_RSA1? PROTOCOL_MAJOR_1 : PROTOCOL_MAJOR_2,
546 	    c->c_keytype == KT_RSA1? PROTOCOL_MINOR_1 : PROTOCOL_MINOR_2);
547 	if (atomicio(write, s, buf, n) != n) {
548 		error("write (%s): %s", c->c_name, strerror(errno));
549 		confree(s);
550 		return;
551 	}
552 	if (c->c_keytype != KT_RSA1) {
553 		keyprint(c, keygrab_ssh2(c));
554 		confree(s);
555 		return;
556 	}
557 	c->c_status = CS_SIZE;
558 	contouch(s);
559 }
560 
561 static void
562 conread(int s)
563 {
564 	con *c = &fdcon[s];
565 	int n;
566 
567 	if (c->c_status == CS_CON) {
568 		congreet(s);
569 		return;
570 	}
571 	n = read(s, c->c_data + c->c_off, c->c_len - c->c_off);
572 	if (n < 0) {
573 		error("read (%s): %s", c->c_name, strerror(errno));
574 		confree(s);
575 		return;
576 	}
577 	c->c_off += n;
578 
579 	if (c->c_off == c->c_len)
580 		switch (c->c_status) {
581 		case CS_SIZE:
582 			c->c_plen = htonl(c->c_plen);
583 			c->c_len = c->c_plen + 8 - (c->c_plen & 7);
584 			c->c_off = 0;
585 			c->c_data = xmalloc(c->c_len);
586 			c->c_status = CS_KEYS;
587 			break;
588 		case CS_KEYS:
589 			keyprint(c, keygrab_ssh1(c));
590 			confree(s);
591 			return;
592 			break;
593 		default:
594 			fatal("conread: invalid status %d", c->c_status);
595 			break;
596 		}
597 
598 	contouch(s);
599 }
600 
601 static void
602 conloop(void)
603 {
604 	struct timeval seltime, now;
605 	fd_set *r, *e;
606 	con *c;
607 	int i;
608 
609 	gettimeofday(&now, NULL);
610 	c = TAILQ_FIRST(&tq);
611 
612 	if (c && (c->c_tv.tv_sec > now.tv_sec ||
613 	    (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec > now.tv_usec))) {
614 		seltime = c->c_tv;
615 		seltime.tv_sec -= now.tv_sec;
616 		seltime.tv_usec -= now.tv_usec;
617 		if (seltime.tv_usec < 0) {
618 			seltime.tv_usec += 1000000;
619 			seltime.tv_sec--;
620 		}
621 	} else
622 		seltime.tv_sec = seltime.tv_usec = 0;
623 
624 	r = xmalloc(read_wait_size);
625 	memcpy(r, read_wait, read_wait_size);
626 	e = xmalloc(read_wait_size);
627 	memcpy(e, read_wait, read_wait_size);
628 
629 	while (select(maxfd, r, NULL, e, &seltime) == -1 &&
630 	    (errno == EAGAIN || errno == EINTR))
631 		;
632 
633 	for (i = 0; i < maxfd; i++) {
634 		if (FD_ISSET(i, e)) {
635 			error("%s: exception!", fdcon[i].c_name);
636 			confree(i);
637 		} else if (FD_ISSET(i, r))
638 			conread(i);
639 	}
640 	xfree(r);
641 	xfree(e);
642 
643 	c = TAILQ_FIRST(&tq);
644 	while (c && (c->c_tv.tv_sec < now.tv_sec ||
645 	    (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec < now.tv_usec))) {
646 		int s = c->c_fd;
647 
648 		c = TAILQ_NEXT(c, c_link);
649 		conrecycle(s);
650 	}
651 }
652 
653 static void
654 do_host(char *host)
655 {
656 	char *name = strnnsep(&host, " \t\n");
657 	int j;
658 
659 	if (name == NULL)
660 		return;
661 	for (j = KT_RSA1; j <= KT_RSA; j *= 2) {
662 		if (get_keytypes & j) {
663 			while (ncon >= MAXCON)
664 				conloop();
665 			conalloc(name, *host ? host : name, j);
666 		}
667 	}
668 }
669 
670 void
671 fatal(const char *fmt,...)
672 {
673 	va_list args;
674 
675 	va_start(args, fmt);
676 	do_log(SYSLOG_LEVEL_FATAL, fmt, args);
677 	va_end(args);
678 	if (nonfatal_fatal)
679 		longjmp(kexjmp, -1);
680 	else
681 		fatal_cleanup();
682 }
683 
684 static void
685 usage(void)
686 {
687 	fprintf(stderr, "usage: %s [-v46] [-p port] [-T timeout] [-f file]\n"
688 	    "\t\t   [host | addrlist namelist] [...]\n",
689 	    __progname);
690 	exit(1);
691 }
692 
693 int
694 main(int argc, char **argv)
695 {
696 	int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
697 	int opt, fopt_count = 0;
698 	char *tname;
699 
700 	extern int optind;
701 	extern char *optarg;
702 
703 	__progname = get_progname(argv[0]);
704 	init_rng();
705 	seed_rng();
706 	TAILQ_INIT(&tq);
707 
708 	if (argc <= 1)
709 		usage();
710 
711 	while ((opt = getopt(argc, argv, "v46p:T:t:f:")) != -1) {
712 		switch (opt) {
713 		case 'p':
714 			ssh_port = a2port(optarg);
715 			if (ssh_port == 0) {
716 				fprintf(stderr, "Bad port '%s'\n", optarg);
717 				exit(1);
718 			}
719 			break;
720 		case 'T':
721 			timeout = convtime(optarg);
722 			if (timeout == -1 || timeout == 0) {
723 				fprintf(stderr, "Bad timeout '%s'\n", optarg);
724 				usage();
725 			}
726 			break;
727 		case 'v':
728 			if (!debug_flag) {
729 				debug_flag = 1;
730 				log_level = SYSLOG_LEVEL_DEBUG1;
731 			}
732 			else if (log_level < SYSLOG_LEVEL_DEBUG3)
733 				log_level++;
734 			else
735 				fatal("Too high debugging level.");
736 			break;
737 		case 'f':
738 			if (strcmp(optarg, "-") == 0)
739 				optarg = NULL;
740 			argv[fopt_count++] = optarg;
741 			break;
742 		case 't':
743 			get_keytypes = 0;
744 			tname = strtok(optarg, ",");
745 			while (tname) {
746 				int type = key_type_from_name(tname);
747 				switch (type) {
748 				case KEY_RSA1:
749 					get_keytypes |= KT_RSA1;
750 					break;
751 				case KEY_DSA:
752 					get_keytypes |= KT_DSA;
753 					break;
754 				case KEY_RSA:
755 					get_keytypes |= KT_RSA;
756 					break;
757 				case KEY_UNSPEC:
758 					fatal("unknown key type %s", tname);
759 				}
760 				tname = strtok(NULL, ",");
761 			}
762 			break;
763 		case '4':
764 			IPv4or6 = AF_INET;
765 			break;
766 		case '6':
767 			IPv4or6 = AF_INET6;
768 			break;
769 		case '?':
770 		default:
771 			usage();
772 		}
773 	}
774 	if (optind == argc && !fopt_count)
775 		usage();
776 
777 	log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1);
778 
779 	maxfd = fdlim_get(1);
780 	if (maxfd < 0)
781 		fatal("%s: fdlim_get: bad value", __progname);
782 	if (maxfd > MAXMAXFD)
783 		maxfd = MAXMAXFD;
784 	if (MAXCON <= 0)
785 		fatal("%s: not enough file descriptors", __progname);
786 	if (maxfd > fdlim_get(0))
787 		fdlim_set(maxfd);
788 	fdcon = xmalloc(maxfd * sizeof(con));
789 	memset(fdcon, 0, maxfd * sizeof(con));
790 
791 	read_wait_size = howmany(maxfd, NFDBITS) * sizeof(fd_mask);
792 	read_wait = xmalloc(read_wait_size);
793 	memset(read_wait, 0, read_wait_size);
794 
795 	if (fopt_count) {
796 		Linebuf *lb;
797 		char *line;
798 		int j;
799 
800 		for (j = 0; j < fopt_count; j++) {
801 			lb = Linebuf_alloc(argv[j], error);
802 			if (!lb)
803 				continue;
804 			while ((line = Linebuf_getline(lb)) != NULL)
805 				do_host(line);
806 			Linebuf_free(lb);
807 		}
808 	}
809 
810 	while (optind < argc)
811 		do_host(argv[optind++]);
812 
813 	while (ncon > 0)
814 		conloop();
815 
816 	return (0);
817 }
818