summaryrefslogtreecommitdiff
path: root/ssh-keyscan.c
blob: 15059f6fa3626dc8582fe7274f14c1aa802a52ca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
/* $OpenBSD: ssh-keyscan.c,v 1.117 2018/02/23 05:14:05 djm Exp $ */
/*
 * Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>.
 *
 * Modification and redistribution in source and binary forms is
 * permitted provided that due credit is given to the author and the
 * OpenBSD project by leaving this copyright notice intact.
 */

#include "includes.h"
 
#include <sys/types.h>
#include "openbsd-compat/sys-queue.h"
#include <sys/resource.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif

#include <netinet/in.h>
#include <arpa/inet.h>

#include <openssl/bn.h>

#include <netdb.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>

#include "xmalloc.h"
#include "ssh.h"
#include "sshbuf.h"
#include "sshkey.h"
#include "cipher.h"
#include "kex.h"
#include "compat.h"
#include "myproposal.h"
#include "packet.h"
#include "dispatch.h"
#include "log.h"
#include "atomicio.h"
#include "misc.h"
#include "hostfile.h"
#include "ssherr.h"
#include "ssh_api.h"
#include "dns.h"

/* Flag indicating whether IPv4 or IPv6.  This can be set on the command line.
   Default value is AF_UNSPEC means both IPv4 and IPv6. */
int IPv4or6 = AF_UNSPEC;

int ssh_port = SSH_DEFAULT_PORT;

#define KT_DSA		(1)
#define KT_RSA		(1<<1)
#define KT_ECDSA	(1<<2)
#define KT_ED25519	(1<<3)

#define KT_MIN		KT_DSA
#define KT_MAX		KT_ED25519

int get_cert = 0;
int get_keytypes = KT_RSA|KT_ECDSA|KT_ED25519;

int hash_hosts = 0;		/* Hash hostname on output */

int print_sshfp = 0;		/* Print SSHFP records instead of known_hosts */

#define MAXMAXFD 256

/* The number of seconds after which to give up on a TCP connection */
int timeout = 5;

int maxfd;
#define MAXCON (maxfd - 10)

extern char *__progname;
fd_set *read_wait;
size_t read_wait_nfdset;
int ncon;

struct ssh *active_state = NULL; /* XXX needed for linking */

/*
 * Keep a connection structure for each file descriptor.  The state
 * associated with file descriptor n is held in fdcon[n].
 */
typedef struct Connection {
	u_char c_status;	/* State of connection on this file desc. */
#define CS_UNUSED 0		/* File descriptor unused */
#define CS_CON 1		/* Waiting to connect/read greeting */
#define CS_SIZE 2		/* Waiting to read initial packet size */
#define CS_KEYS 3		/* Waiting to read public key packet */
	int c_fd;		/* Quick lookup: c->c_fd == c - fdcon */
	int c_plen;		/* Packet length field for ssh packet */
	int c_len;		/* Total bytes which must be read. */
	int c_off;		/* Length of data read so far. */
	int c_keytype;		/* Only one of KT_* */
	sig_atomic_t c_done;	/* SSH2 done */
	char *c_namebase;	/* Address to free for c_name and c_namelist */
	char *c_name;		/* Hostname of connection for errors */
	char *c_namelist;	/* Pointer to other possible addresses */
	char *c_output_name;	/* Hostname of connection for output */
	char *c_data;		/* Data read from this fd */
	struct ssh *c_ssh;	/* SSH-connection */
	struct timeval c_tv;	/* Time at which connection gets aborted */
	TAILQ_ENTRY(Connection) c_link;	/* List of connections in timeout order. */
} con;

TAILQ_HEAD(conlist, Connection) tq;	/* Timeout Queue */
con *fdcon;

static void keyprint(con *c, struct sshkey *key);

static int
fdlim_get(int hard)
{
#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
	struct rlimit rlfd;

	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
		return (-1);
	if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY)
		return SSH_SYSFDMAX;
	else
		return hard ? rlfd.rlim_max : rlfd.rlim_cur;
#else
	return SSH_SYSFDMAX;
#endif
}

static int
fdlim_set(int lim)
{
#if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
	struct rlimit rlfd;
#endif

	if (lim <= 0)
		return (-1);
#if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
		return (-1);
	rlfd.rlim_cur = lim;
	if (setrlimit(RLIMIT_NOFILE, &rlfd) < 0)
		return (-1);
#elif defined (HAVE_SETDTABLESIZE)
	setdtablesize(lim);
#endif
	return (0);
}

/*
 * This is an strsep function that returns a null field for adjacent
 * separators.  This is the same as the 4.4BSD strsep, but different from the
 * one in the GNU libc.
 */
static char *
xstrsep(char **str, const char *delim)
{
	char *s, *e;

	if (!**str)
		return (NULL);

	s = *str;
	e = s + strcspn(s, delim);

	if (*e != '\0')
		*e++ = '\0';
	*str = e;

	return (s);
}

/*
 * Get the next non-null token (like GNU strsep).  Strsep() will return a
 * null token for two adjacent separators, so we may have to loop.
 */
static char *
strnnsep(char **stringp, char *delim)
{
	char *tok;

	do {
		tok = xstrsep(stringp, delim);
	} while (tok && *tok == '\0');
	return (tok);
}


static int
key_print_wrapper(struct sshkey *hostkey, struct ssh *ssh)
{
	con *c;

	if ((c = ssh_get_app_data(ssh)) != NULL)
		keyprint(c, hostkey);
	/* always abort key exchange */
	return -1;
}

static int
ssh2_capable(int remote_major, int remote_minor)
{
	switch (remote_major) {
	case 1:
		if (remote_minor == 99)
			return 1;
		break;
	case 2:
		return 1;
	default:
		break;
	}
	return 0;
}

static void
keygrab_ssh2(con *c)
{
	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
	int r;

	switch (c->c_keytype) {
	case KT_DSA:
		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
		    "ssh-dss-cert-v01@openssh.com" : "ssh-dss";
		break;
	case KT_RSA:
		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
		    "ssh-rsa-cert-v01@openssh.com" : "ssh-rsa";
		break;
	case KT_ED25519:
		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
		    "ssh-ed25519-cert-v01@openssh.com" : "ssh-ed25519";
		break;
	case KT_ECDSA:
		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
		    "ecdsa-sha2-nistp256-cert-v01@openssh.com,"
		    "ecdsa-sha2-nistp384-cert-v01@openssh.com,"
		    "ecdsa-sha2-nistp521-cert-v01@openssh.com" :
		    "ecdsa-sha2-nistp256,"
		    "ecdsa-sha2-nistp384,"
		    "ecdsa-sha2-nistp521";
		break;
	default:
		fatal("unknown key type %d", c->c_keytype);
		break;
	}
	if ((r = kex_setup(c->c_ssh, myproposal)) != 0) {
		free(c->c_ssh);
		fprintf(stderr, "kex_setup: %s\n", ssh_err(r));
		exit(1);
	}
#ifdef WITH_OPENSSL
	c->c_ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client;
	c->c_ssh->kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client;
	c->c_ssh->kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client;
	c->c_ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
	c->c_ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
# ifdef OPENSSL_HAS_ECC
	c->c_ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
# endif
#endif
	c->c_ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client;
	ssh_set_verify_host_key_callback(c->c_ssh, key_print_wrapper);
	/*
	 * do the key-exchange until an error occurs or until
	 * the key_print_wrapper() callback sets c_done.
	 */
	ssh_dispatch_run(c->c_ssh, DISPATCH_BLOCK, &c->c_done);
}

static void
keyprint_one(const char *host, struct sshkey *key)
{
	char *hostport;
	const char *known_host, *hashed;

	if (print_sshfp) {
		export_dns_rr(host, key, stdout, 0);
		return;
	}

	hostport = put_host_port(host, ssh_port);
	lowercase(hostport);
	if (hash_hosts && (hashed = host_hash(host, NULL, 0)) == NULL)
		fatal("host_hash failed");
	known_host = hash_hosts ? hashed : hostport;
	if (!get_cert)
		fprintf(stdout, "%s ", known_host);
	sshkey_write(key, stdout);
	fputs("\n", stdout);
	free(hostport);
}

static void
keyprint(con *c, struct sshkey *key)
{
	char *hosts = c->c_output_name ? c->c_output_name : c->c_name;
	char *host, *ohosts;

	if (key == NULL)
		return;
	if (get_cert || (!hash_hosts && ssh_port == SSH_DEFAULT_PORT)) {
		keyprint_one(hosts, key);
		return;
	}
	ohosts = hosts = xstrdup(hosts);
	while ((host = strsep(&hosts, ",")) != NULL)
		keyprint_one(host, key);
	free(ohosts);
}

static int
tcpconnect(char *host)
{
	struct addrinfo hints, *ai, *aitop;
	char strport[NI_MAXSERV];
	int gaierr, s = -1;

	snprintf(strport, sizeof strport, "%d", ssh_port);
	memset(&hints, 0, sizeof(hints));
	hints.ai_family = IPv4or6;
	hints.ai_socktype = SOCK_STREAM;
	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
		error("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr));
		return -1;
	}
	for (ai = aitop; ai; ai = ai->ai_next) {
		s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
		if (s < 0) {
			error("socket: %s", strerror(errno));
			continue;
		}
		if (set_nonblock(s) == -1)
			fatal("%s: set_nonblock(%d)", __func__, s);
		if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0 &&
		    errno != EINPROGRESS)
			error("connect (`%s'): %s", host, strerror(errno));
		else
			break;
		close(s);
		s = -1;
	}
	freeaddrinfo(aitop);
	return s;
}

static int
conalloc(char *iname, char *oname, int keytype)
{
	char *namebase, *name, *namelist;
	int s;

	namebase = namelist = xstrdup(iname);

	do {
		name = xstrsep(&namelist, ",");
		if (!name) {
			free(namebase);
			return (-1);
		}
	} while ((s = tcpconnect(name)) < 0);

	if (s >= maxfd)
		fatal("conalloc: fdno %d too high", s);
	if (fdcon[s].c_status)
		fatal("conalloc: attempt to reuse fdno %d", s);

	debug3("%s: oname %s kt %d", __func__, oname, keytype);
	fdcon[s].c_fd = s;
	fdcon[s].c_status = CS_CON;
	fdcon[s].c_namebase = namebase;
	fdcon[s].c_name = name;
	fdcon[s].c_namelist = namelist;
	fdcon[s].c_output_name = xstrdup(oname);
	fdcon[s].c_data = (char *) &fdcon[s].c_plen;
	fdcon[s].c_len = 4;
	fdcon[s].c_off = 0;
	fdcon[s].c_keytype = keytype;
	monotime_tv(&fdcon[s].c_tv);
	fdcon[s].c_tv.tv_sec += timeout;
	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
	FD_SET(s, read_wait);
	ncon++;
	return (s);
}

static void
confree(int s)
{
	if (s >= maxfd || fdcon[s].c_status == CS_UNUSED)
		fatal("confree: attempt to free bad fdno %d", s);
	free(fdcon[s].c_namebase);
	free(fdcon[s].c_output_name);
	if (fdcon[s].c_status == CS_KEYS)
		free(fdcon[s].c_data);
	fdcon[s].c_status = CS_UNUSED;
	fdcon[s].c_keytype = 0;
	if (fdcon[s].c_ssh) {
		ssh_packet_close(fdcon[s].c_ssh);
		free(fdcon[s].c_ssh);
		fdcon[s].c_ssh = NULL;
	} else
		close(s);
	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
	FD_CLR(s, read_wait);
	ncon--;
}

static void
contouch(int s)
{
	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
	monotime_tv(&fdcon[s].c_tv);
	fdcon[s].c_tv.tv_sec += timeout;
	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
}

static int
conrecycle(int s)
{
	con *c = &fdcon[s];
	int ret;

	ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
	confree(s);
	return (ret);
}

static void
congreet(int s)
{
	int n = 0, remote_major = 0, remote_minor = 0;
	char buf[256], *cp;
	char remote_version[sizeof buf];
	size_t bufsiz;
	con *c = &fdcon[s];

	/* send client banner */
	n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
	    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2);
	if (n < 0 || (size_t)n >= sizeof(buf)) {
		error("snprintf: buffer too small");
		confree(s);
		return;
	}
	if (atomicio(vwrite, s, buf, n) != (size_t)n) {
		error("write (%s): %s", c->c_name, strerror(errno));
		confree(s);
		return;
	}

	for (;;) {
		memset(buf, '\0', sizeof(buf));
		bufsiz = sizeof(buf);
		cp = buf;
		while (bufsiz-- &&
		    (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') {
			if (*cp == '\r')
				*cp = '\n';
			cp++;
		}
		if (n != 1 || strncmp(buf, "SSH-", 4) == 0)
			break;
	}
	if (n == 0) {
		switch (errno) {
		case EPIPE:
			error("%s: Connection closed by remote host", c->c_name);
			break;
		case ECONNREFUSED:
			break;
		default:
			error("read (%s): %s", c->c_name, strerror(errno));
			break;
		}
		conrecycle(s);
		return;
	}
	if (*cp != '\n' && *cp != '\r') {
		error("%s: bad greeting", c->c_name);
		confree(s);
		return;
	}
	*cp = '\0';
	if ((c->c_ssh = ssh_packet_set_connection(NULL, s, s)) == NULL)
		fatal("ssh_packet_set_connection failed");
	ssh_packet_set_timeout(c->c_ssh, timeout, 1);
	ssh_set_app_data(c->c_ssh, c);	/* back link */
	if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
	    &remote_major, &remote_minor, remote_version) == 3)
		c->c_ssh->compat = compat_datafellows(remote_version);
	else
		c->c_ssh->compat = 0;
	if (!ssh2_capable(remote_major, remote_minor)) {
		debug("%s doesn't support ssh2", c->c_name);
		confree(s);
		return;
	}
	fprintf(stderr, "%c %s:%d %s\n", print_sshfp ? ';' : '#',
	    c->c_name, ssh_port, chop(buf));
	keygrab_ssh2(c);
	confree(s);
}

static void
conread(int s)
{
	con *c = &fdcon[s];
	size_t n;

	if (c->c_status == CS_CON) {
		congreet(s);
		return;
	}
	n = atomicio(read, s, c->c_data + c->c_off, c->c_len - c->c_off);
	if (n == 0) {
		error("read (%s): %s", c->c_name, strerror(errno));
		confree(s);
		return;
	}
	c->c_off += n;

	if (c->c_off == c->c_len)
		switch (c->c_status) {
		case CS_SIZE:
			c->c_plen = htonl(c->c_plen);
			c->c_len = c->c_plen + 8 - (c->c_plen & 7);
			c->c_off = 0;
			c->c_data = xmalloc(c->c_len);
			c->c_status = CS_KEYS;
			break;
		default:
			fatal("conread: invalid status %d", c->c_status);
			break;
		}

	contouch(s);
}

static void
conloop(void)
{
	struct timeval seltime, now;
	fd_set *r, *e;
	con *c;
	int i;

	monotime_tv(&now);
	c = TAILQ_FIRST(&tq);

	if (c && (c->c_tv.tv_sec > now.tv_sec ||
	    (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec > now.tv_usec))) {
		seltime = c->c_tv;
		seltime.tv_sec -= now.tv_sec;
		seltime.tv_usec -= now.tv_usec;
		if (seltime.tv_usec < 0) {
			seltime.tv_usec += 1000000;
			seltime.tv_sec--;
		}
	} else
		timerclear(&seltime);

	r = xcalloc(read_wait_nfdset, sizeof(fd_mask));
	e = xcalloc(read_wait_nfdset, sizeof(fd_mask));
	memcpy(r, read_wait, read_wait_nfdset * sizeof(fd_mask));
	memcpy(e, read_wait, read_wait_nfdset * sizeof(fd_mask));

	while (select(maxfd, r, NULL, e, &seltime) == -1 &&
	    (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK))
		;

	for (i = 0; i < maxfd; i++) {
		if (FD_ISSET(i, e)) {
			error("%s: exception!", fdcon[i].c_name);
			confree(i);
		} else if (FD_ISSET(i, r))
			conread(i);
	}
	free(r);
	free(e);

	c = TAILQ_FIRST(&tq);
	while (c && (c->c_tv.tv_sec < now.tv_sec ||
	    (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec < now.tv_usec))) {
		int s = c->c_fd;

		c = TAILQ_NEXT(c, c_link);
		conrecycle(s);
	}
}

static void
do_host(char *host)
{
	char *name = strnnsep(&host, " \t\n");
	int j;

	if (name == NULL)
		return;
	for (j = KT_MIN; j <= KT_MAX; j *= 2) {
		if (get_keytypes & j) {
			while (ncon >= MAXCON)
				conloop();
			conalloc(name, *host ? host : name, j);
		}
	}
}

void
fatal(const char *fmt,...)
{
	va_list args;

	va_start(args, fmt);
	do_log(SYSLOG_LEVEL_FATAL, fmt, args);
	va_end(args);
	exit(255);
}

static void
usage(void)
{
	fprintf(stderr,
	    "usage: %s [-46cDHv] [-f file] [-p port] [-T timeout] [-t type]\n"
	    "\t\t   [host | addrlist namelist] ...\n",
	    __progname);
	exit(1);
}

int
main(int argc, char **argv)
{
	int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
	int opt, fopt_count = 0, j;
	char *tname, *cp, line[NI_MAXHOST];
	FILE *fp;
	u_long linenum;

	extern int optind;
	extern char *optarg;

	ssh_malloc_init();	/* must be called before any mallocs */
	__progname = ssh_get_progname(argv[0]);
	seed_rng();
	TAILQ_INIT(&tq);

	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
	sanitise_stdfd();

	if (argc <= 1)
		usage();

	while ((opt = getopt(argc, argv, "cDHv46p:T:t:f:")) != -1) {
		switch (opt) {
		case 'H':
			hash_hosts = 1;
			break;
		case 'c':
			get_cert = 1;
			break;
		case 'D':
			print_sshfp = 1;
			break;
		case 'p':
			ssh_port = a2port(optarg);
			if (ssh_port <= 0) {
				fprintf(stderr, "Bad port '%s'\n", optarg);
				exit(1);
			}
			break;
		case 'T':
			timeout = convtime(optarg);
			if (timeout == -1 || timeout == 0) {
				fprintf(stderr, "Bad timeout '%s'\n", optarg);
				usage();
			}
			break;
		case 'v':
			if (!debug_flag) {
				debug_flag = 1;
				log_level = SYSLOG_LEVEL_DEBUG1;
			}
			else if (log_level < SYSLOG_LEVEL_DEBUG3)
				log_level++;
			else
				fatal("Too high debugging level.");
			break;
		case 'f':
			if (strcmp(optarg, "-") == 0)
				optarg = NULL;
			argv[fopt_count++] = optarg;
			break;
		case 't':
			get_keytypes = 0;
			tname = strtok(optarg, ",");
			while (tname) {
				int type = sshkey_type_from_name(tname);

				switch (type) {
				case KEY_DSA:
					get_keytypes |= KT_DSA;
					break;
				case KEY_ECDSA:
					get_keytypes |= KT_ECDSA;
					break;
				case KEY_RSA:
					get_keytypes |= KT_RSA;
					break;
				case KEY_ED25519:
					get_keytypes |= KT_ED25519;
					break;
				case KEY_UNSPEC:
				default:
					fatal("Unknown key type \"%s\"", tname);
				}
				tname = strtok(NULL, ",");
			}
			break;
		case '4':
			IPv4or6 = AF_INET;
			break;
		case '6':
			IPv4or6 = AF_INET6;
			break;
		case '?':
		default:
			usage();
		}
	}
	if (optind == argc && !fopt_count)
		usage();

	log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1);

	maxfd = fdlim_get(1);
	if (maxfd < 0)
		fatal("%s: fdlim_get: bad value", __progname);
	if (maxfd > MAXMAXFD)
		maxfd = MAXMAXFD;
	if (MAXCON <= 0)
		fatal("%s: not enough file descriptors", __progname);
	if (maxfd > fdlim_get(0))
		fdlim_set(maxfd);
	fdcon = xcalloc(maxfd, sizeof(con));

	read_wait_nfdset = howmany(maxfd, NFDBITS);
	read_wait = xcalloc(read_wait_nfdset, sizeof(fd_mask));

	for (j = 0; j < fopt_count; j++) {
		if (argv[j] == NULL)
			fp = stdin;
		else if ((fp = fopen(argv[j], "r")) == NULL)
			fatal("%s: %s: %s", __progname, argv[j],
			    strerror(errno));
		linenum = 0;

		while (read_keyfile_line(fp,
		    argv[j] == NULL ? "(stdin)" : argv[j], line, sizeof(line),
		    &linenum) != -1) {
			/* Chomp off trailing whitespace and comments */
			if ((cp = strchr(line, '#')) == NULL)
				cp = line + strlen(line) - 1;
			while (cp >= line) {
				if (*cp == ' ' || *cp == '\t' ||
				    *cp == '\n' || *cp == '#')
					*cp-- = '\0';
				else
					break;
			}

			/* Skip empty lines */
			if (*line == '\0')
				continue;

			do_host(line);
		}

		if (ferror(fp))
			fatal("%s: %s: %s", __progname, argv[j],
			    strerror(errno));

		fclose(fp);
	}

	while (optind < argc)
		do_host(argv[optind++]);

	while (ncon > 0)
		conloop();

	return (0);
}