xref: /dragonfly/crypto/openssh/ssh-keyscan.c (revision a72de5ad) 
1 /* $OpenBSD: ssh-keyscan.c,v 1.115 2017/06/30 04:17:23 dtucker Exp $ */
2 /*
3  * Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>.
4  *
5  * Modification and redistribution in source and binary forms is
6  * permitted provided that due credit is given to the author and the
7  * OpenBSD project by leaving this copyright notice intact.
8  */
9 
10 #include "includes.h"
11 
12 #include <sys/types.h>
13 #include "openbsd-compat/sys-queue.h"
14 #include <sys/resource.h>
15 #ifdef HAVE_SYS_TIME_H
16 # include <sys/time.h>
17 #endif
18 
19 #include <netinet/in.h>
20 #include <arpa/inet.h>
21 
22 #include <openssl/bn.h>
23 
24 #include <netdb.h>
25 #include <errno.h>
26 #include <stdarg.h>
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <signal.h>
30 #include <string.h>
31 #include <unistd.h>
32 
33 #include "xmalloc.h"
34 #include "ssh.h"
35 #include "sshbuf.h"
36 #include "sshkey.h"
37 #include "cipher.h"
38 #include "kex.h"
39 #include "compat.h"
40 #include "myproposal.h"
41 #include "packet.h"
42 #include "dispatch.h"
43 #include "log.h"
44 #include "atomicio.h"
45 #include "misc.h"
46 #include "hostfile.h"
47 #include "ssherr.h"
48 #include "ssh_api.h"
49 
50 /* Flag indicating whether IPv4 or IPv6.  This can be set on the command line.
51    Default value is AF_UNSPEC means both IPv4 and IPv6. */
52 int IPv4or6 = AF_UNSPEC;
53 
54 int ssh_port = SSH_DEFAULT_PORT;
55 
56 #define KT_DSA		(1)
57 #define KT_RSA		(1<<1)
58 #define KT_ECDSA	(1<<2)
59 #define KT_ED25519	(1<<3)
60 
61 #define KT_MIN		KT_DSA
62 #define KT_MAX		KT_ED25519
63 
64 int get_cert = 0;
65 int get_keytypes = KT_RSA|KT_ECDSA|KT_ED25519;
66 
67 int hash_hosts = 0;		/* Hash hostname on output */
68 
69 #define MAXMAXFD 256
70 
71 /* The number of seconds after which to give up on a TCP connection */
72 int timeout = 5;
73 
74 int maxfd;
75 #define MAXCON (maxfd - 10)
76 
77 extern char *__progname;
78 fd_set *read_wait;
79 size_t read_wait_nfdset;
80 int ncon;
81 
82 struct ssh *active_state = NULL; /* XXX needed for linking */
83 
84 /*
85  * Keep a connection structure for each file descriptor.  The state
86  * associated with file descriptor n is held in fdcon[n].
87  */
88 typedef struct Connection {
89 	u_char c_status;	/* State of connection on this file desc. */
90 #define CS_UNUSED 0		/* File descriptor unused */
91 #define CS_CON 1		/* Waiting to connect/read greeting */
92 #define CS_SIZE 2		/* Waiting to read initial packet size */
93 #define CS_KEYS 3		/* Waiting to read public key packet */
94 	int c_fd;		/* Quick lookup: c->c_fd == c - fdcon */
95 	int c_plen;		/* Packet length field for ssh packet */
96 	int c_len;		/* Total bytes which must be read. */
97 	int c_off;		/* Length of data read so far. */
98 	int c_keytype;		/* Only one of KT_* */
99 	sig_atomic_t c_done;	/* SSH2 done */
100 	char *c_namebase;	/* Address to free for c_name and c_namelist */
101 	char *c_name;		/* Hostname of connection for errors */
102 	char *c_namelist;	/* Pointer to other possible addresses */
103 	char *c_output_name;	/* Hostname of connection for output */
104 	char *c_data;		/* Data read from this fd */
105 	struct ssh *c_ssh;	/* SSH-connection */
106 	struct timeval c_tv;	/* Time at which connection gets aborted */
107 	TAILQ_ENTRY(Connection) c_link;	/* List of connections in timeout order. */
108 } con;
109 
110 TAILQ_HEAD(conlist, Connection) tq;	/* Timeout Queue */
111 con *fdcon;
112 
113 static void keyprint(con *c, struct sshkey *key);
114 
115 static int
116 fdlim_get(int hard)
117 {
118 #if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
119 	struct rlimit rlfd;
120 
121 	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
122 		return (-1);
123 	if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY)
124 		return SSH_SYSFDMAX;
125 	else
126 		return hard ? rlfd.rlim_max : rlfd.rlim_cur;
127 #else
128 	return SSH_SYSFDMAX;
129 #endif
130 }
131 
132 static int
133 fdlim_set(int lim)
134 {
135 #if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
136 	struct rlimit rlfd;
137 #endif
138 
139 	if (lim <= 0)
140 		return (-1);
141 #if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
142 	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
143 		return (-1);
144 	rlfd.rlim_cur = lim;
145 	if (setrlimit(RLIMIT_NOFILE, &rlfd) < 0)
146 		return (-1);
147 #elif defined (HAVE_SETDTABLESIZE)
148 	setdtablesize(lim);
149 #endif
150 	return (0);
151 }
152 
153 /*
154  * This is an strsep function that returns a null field for adjacent
155  * separators.  This is the same as the 4.4BSD strsep, but different from the
156  * one in the GNU libc.
157  */
158 static char *
159 xstrsep(char **str, const char *delim)
160 {
161 	char *s, *e;
162 
163 	if (!**str)
164 		return (NULL);
165 
166 	s = *str;
167 	e = s + strcspn(s, delim);
168 
169 	if (*e != '\0')
170 		*e++ = '\0';
171 	*str = e;
172 
173 	return (s);
174 }
175 
176 /*
177  * Get the next non-null token (like GNU strsep).  Strsep() will return a
178  * null token for two adjacent separators, so we may have to loop.
179  */
180 static char *
181 strnnsep(char **stringp, char *delim)
182 {
183 	char *tok;
184 
185 	do {
186 		tok = xstrsep(stringp, delim);
187 	} while (tok && *tok == '\0');
188 	return (tok);
189 }
190 
191 
192 static int
193 key_print_wrapper(struct sshkey *hostkey, struct ssh *ssh)
194 {
195 	con *c;
196 
197 	if ((c = ssh_get_app_data(ssh)) != NULL)
198 		keyprint(c, hostkey);
199 	/* always abort key exchange */
200 	return -1;
201 }
202 
203 static int
204 ssh2_capable(int remote_major, int remote_minor)
205 {
206 	switch (remote_major) {
207 	case 1:
208 		if (remote_minor == 99)
209 			return 1;
210 		break;
211 	case 2:
212 		return 1;
213 	default:
214 		break;
215 	}
216 	return 0;
217 }
218 
219 static void
220 keygrab_ssh2(con *c)
221 {
222 	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
223 	int r;
224 
225 	switch (c->c_keytype) {
226 	case KT_DSA:
227 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
228 		    "ssh-dss-cert-v01@openssh.com" : "ssh-dss";
229 		break;
230 	case KT_RSA:
231 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
232 		    "ssh-rsa-cert-v01@openssh.com" : "ssh-rsa";
233 		break;
234 	case KT_ED25519:
235 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
236 		    "ssh-ed25519-cert-v01@openssh.com" : "ssh-ed25519";
237 		break;
238 	case KT_ECDSA:
239 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
240 		    "ecdsa-sha2-nistp256-cert-v01@openssh.com,"
241 		    "ecdsa-sha2-nistp384-cert-v01@openssh.com,"
242 		    "ecdsa-sha2-nistp521-cert-v01@openssh.com" :
243 		    "ecdsa-sha2-nistp256,"
244 		    "ecdsa-sha2-nistp384,"
245 		    "ecdsa-sha2-nistp521";
246 		break;
247 	default:
248 		fatal("unknown key type %d", c->c_keytype);
249 		break;
250 	}
251 	if ((r = kex_setup(c->c_ssh, myproposal)) != 0) {
252 		free(c->c_ssh);
253 		fprintf(stderr, "kex_setup: %s\n", ssh_err(r));
254 		exit(1);
255 	}
256 #ifdef WITH_OPENSSL
257 	c->c_ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
258 	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
259 	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client;
260 	c->c_ssh->kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client;
261 	c->c_ssh->kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client;
262 	c->c_ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
263 	c->c_ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
264 # ifdef OPENSSL_HAS_ECC
265 	c->c_ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
266 # endif
267 #endif
268 	c->c_ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client;
269 	ssh_set_verify_host_key_callback(c->c_ssh, key_print_wrapper);
270 	/*
271 	 * do the key-exchange until an error occurs or until
272 	 * the key_print_wrapper() callback sets c_done.
273 	 */
274 	ssh_dispatch_run(c->c_ssh, DISPATCH_BLOCK, &c->c_done);
275 }
276 
277 static void
278 keyprint_one(const char *host, struct sshkey *key)
279 {
280 	char *hostport;
281 	const char *known_host, *hashed;
282 
283 	hostport = put_host_port(host, ssh_port);
284 	lowercase(hostport);
285 	if (hash_hosts && (hashed = host_hash(host, NULL, 0)) == NULL)
286 		fatal("host_hash failed");
287 	known_host = hash_hosts ? hashed : hostport;
288 	if (!get_cert)
289 		fprintf(stdout, "%s ", known_host);
290 	sshkey_write(key, stdout);
291 	fputs("\n", stdout);
292 	free(hostport);
293 }
294 
295 static void
296 keyprint(con *c, struct sshkey *key)
297 {
298 	char *hosts = c->c_output_name ? c->c_output_name : c->c_name;
299 	char *host, *ohosts;
300 
301 	if (key == NULL)
302 		return;
303 	if (get_cert || (!hash_hosts && ssh_port == SSH_DEFAULT_PORT)) {
304 		keyprint_one(hosts, key);
305 		return;
306 	}
307 	ohosts = hosts = xstrdup(hosts);
308 	while ((host = strsep(&hosts, ",")) != NULL)
309 		keyprint_one(host, key);
310 	free(ohosts);
311 }
312 
313 static int
314 tcpconnect(char *host)
315 {
316 	struct addrinfo hints, *ai, *aitop;
317 	char strport[NI_MAXSERV];
318 	int gaierr, s = -1;
319 
320 	snprintf(strport, sizeof strport, "%d", ssh_port);
321 	memset(&hints, 0, sizeof(hints));
322 	hints.ai_family = IPv4or6;
323 	hints.ai_socktype = SOCK_STREAM;
324 	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
325 		error("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr));
326 		return -1;
327 	}
328 	for (ai = aitop; ai; ai = ai->ai_next) {
329 		s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
330 		if (s < 0) {
331 			error("socket: %s", strerror(errno));
332 			continue;
333 		}
334 		if (set_nonblock(s) == -1)
335 			fatal("%s: set_nonblock(%d)", __func__, s);
336 		if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0 &&
337 		    errno != EINPROGRESS)
338 			error("connect (`%s'): %s", host, strerror(errno));
339 		else
340 			break;
341 		close(s);
342 		s = -1;
343 	}
344 	freeaddrinfo(aitop);
345 	return s;
346 }
347 
348 static int
349 conalloc(char *iname, char *oname, int keytype)
350 {
351 	char *namebase, *name, *namelist;
352 	int s;
353 
354 	namebase = namelist = xstrdup(iname);
355 
356 	do {
357 		name = xstrsep(&namelist, ",");
358 		if (!name) {
359 			free(namebase);
360 			return (-1);
361 		}
362 	} while ((s = tcpconnect(name)) < 0);
363 
364 	if (s >= maxfd)
365 		fatal("conalloc: fdno %d too high", s);
366 	if (fdcon[s].c_status)
367 		fatal("conalloc: attempt to reuse fdno %d", s);
368 
369 	debug3("%s: oname %s kt %d", __func__, oname, keytype);
370 	fdcon[s].c_fd = s;
371 	fdcon[s].c_status = CS_CON;
372 	fdcon[s].c_namebase = namebase;
373 	fdcon[s].c_name = name;
374 	fdcon[s].c_namelist = namelist;
375 	fdcon[s].c_output_name = xstrdup(oname);
376 	fdcon[s].c_data = (char *) &fdcon[s].c_plen;
377 	fdcon[s].c_len = 4;
378 	fdcon[s].c_off = 0;
379 	fdcon[s].c_keytype = keytype;
380 	gettimeofday(&fdcon[s].c_tv, NULL);
381 	fdcon[s].c_tv.tv_sec += timeout;
382 	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
383 	FD_SET(s, read_wait);
384 	ncon++;
385 	return (s);
386 }
387 
388 static void
389 confree(int s)
390 {
391 	if (s >= maxfd || fdcon[s].c_status == CS_UNUSED)
392 		fatal("confree: attempt to free bad fdno %d", s);
393 	free(fdcon[s].c_namebase);
394 	free(fdcon[s].c_output_name);
395 	if (fdcon[s].c_status == CS_KEYS)
396 		free(fdcon[s].c_data);
397 	fdcon[s].c_status = CS_UNUSED;
398 	fdcon[s].c_keytype = 0;
399 	if (fdcon[s].c_ssh) {
400 		ssh_packet_close(fdcon[s].c_ssh);
401 		free(fdcon[s].c_ssh);
402 		fdcon[s].c_ssh = NULL;
403 	} else
404 		close(s);
405 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
406 	FD_CLR(s, read_wait);
407 	ncon--;
408 }
409 
410 static void
411 contouch(int s)
412 {
413 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
414 	gettimeofday(&fdcon[s].c_tv, NULL);
415 	fdcon[s].c_tv.tv_sec += timeout;
416 	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
417 }
418 
419 static int
420 conrecycle(int s)
421 {
422 	con *c = &fdcon[s];
423 	int ret;
424 
425 	ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
426 	confree(s);
427 	return (ret);
428 }
429 
430 static void
431 congreet(int s)
432 {
433 	int n = 0, remote_major = 0, remote_minor = 0;
434 	char buf[256], *cp;
435 	char remote_version[sizeof buf];
436 	size_t bufsiz;
437 	con *c = &fdcon[s];
438 
439 	/* send client banner */
440 	n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
441 	    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2);
442 	if (n < 0 || (size_t)n >= sizeof(buf)) {
443 		error("snprintf: buffer too small");
444 		confree(s);
445 		return;
446 	}
447 	if (atomicio(vwrite, s, buf, n) != (size_t)n) {
448 		error("write (%s): %s", c->c_name, strerror(errno));
449 		confree(s);
450 		return;
451 	}
452 
453 	for (;;) {
454 		memset(buf, '\0', sizeof(buf));
455 		bufsiz = sizeof(buf);
456 		cp = buf;
457 		while (bufsiz-- &&
458 		    (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') {
459 			if (*cp == '\r')
460 				*cp = '\n';
461 			cp++;
462 		}
463 		if (n != 1 || strncmp(buf, "SSH-", 4) == 0)
464 			break;
465 	}
466 	if (n == 0) {
467 		switch (errno) {
468 		case EPIPE:
469 			error("%s: Connection closed by remote host", c->c_name);
470 			break;
471 		case ECONNREFUSED:
472 			break;
473 		default:
474 			error("read (%s): %s", c->c_name, strerror(errno));
475 			break;
476 		}
477 		conrecycle(s);
478 		return;
479 	}
480 	if (*cp != '\n' && *cp != '\r') {
481 		error("%s: bad greeting", c->c_name);
482 		confree(s);
483 		return;
484 	}
485 	*cp = '\0';
486 	if ((c->c_ssh = ssh_packet_set_connection(NULL, s, s)) == NULL)
487 		fatal("ssh_packet_set_connection failed");
488 	ssh_packet_set_timeout(c->c_ssh, timeout, 1);
489 	ssh_set_app_data(c->c_ssh, c);	/* back link */
490 	if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
491 	    &remote_major, &remote_minor, remote_version) == 3)
492 		c->c_ssh->compat = compat_datafellows(remote_version);
493 	else
494 		c->c_ssh->compat = 0;
495 	if (!ssh2_capable(remote_major, remote_minor)) {
496 		debug("%s doesn't support ssh2", c->c_name);
497 		confree(s);
498 		return;
499 	}
500 	fprintf(stderr, "# %s:%d %s\n", c->c_name, ssh_port, chop(buf));
501 	keygrab_ssh2(c);
502 	confree(s);
503 }
504 
505 static void
506 conread(int s)
507 {
508 	con *c = &fdcon[s];
509 	size_t n;
510 
511 	if (c->c_status == CS_CON) {
512 		congreet(s);
513 		return;
514 	}
515 	n = atomicio(read, s, c->c_data + c->c_off, c->c_len - c->c_off);
516 	if (n == 0) {
517 		error("read (%s): %s", c->c_name, strerror(errno));
518 		confree(s);
519 		return;
520 	}
521 	c->c_off += n;
522 
523 	if (c->c_off == c->c_len)
524 		switch (c->c_status) {
525 		case CS_SIZE:
526 			c->c_plen = htonl(c->c_plen);
527 			c->c_len = c->c_plen + 8 - (c->c_plen & 7);
528 			c->c_off = 0;
529 			c->c_data = xmalloc(c->c_len);
530 			c->c_status = CS_KEYS;
531 			break;
532 		default:
533 			fatal("conread: invalid status %d", c->c_status);
534 			break;
535 		}
536 
537 	contouch(s);
538 }
539 
540 static void
541 conloop(void)
542 {
543 	struct timeval seltime, now;
544 	fd_set *r, *e;
545 	con *c;
546 	int i;
547 
548 	gettimeofday(&now, NULL);
549 	c = TAILQ_FIRST(&tq);
550 
551 	if (c && (c->c_tv.tv_sec > now.tv_sec ||
552 	    (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec > now.tv_usec))) {
553 		seltime = c->c_tv;
554 		seltime.tv_sec -= now.tv_sec;
555 		seltime.tv_usec -= now.tv_usec;
556 		if (seltime.tv_usec < 0) {
557 			seltime.tv_usec += 1000000;
558 			seltime.tv_sec--;
559 		}
560 	} else
561 		timerclear(&seltime);
562 
563 	r = xcalloc(read_wait_nfdset, sizeof(fd_mask));
564 	e = xcalloc(read_wait_nfdset, sizeof(fd_mask));
565 	memcpy(r, read_wait, read_wait_nfdset * sizeof(fd_mask));
566 	memcpy(e, read_wait, read_wait_nfdset * sizeof(fd_mask));
567 
568 	while (select(maxfd, r, NULL, e, &seltime) == -1 &&
569 	    (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK))
570 		;
571 
572 	for (i = 0; i < maxfd; i++) {
573 		if (FD_ISSET(i, e)) {
574 			error("%s: exception!", fdcon[i].c_name);
575 			confree(i);
576 		} else if (FD_ISSET(i, r))
577 			conread(i);
578 	}
579 	free(r);
580 	free(e);
581 
582 	c = TAILQ_FIRST(&tq);
583 	while (c && (c->c_tv.tv_sec < now.tv_sec ||
584 	    (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec < now.tv_usec))) {
585 		int s = c->c_fd;
586 
587 		c = TAILQ_NEXT(c, c_link);
588 		conrecycle(s);
589 	}
590 }
591 
592 static void
593 do_host(char *host)
594 {
595 	char *name = strnnsep(&host, " \t\n");
596 	int j;
597 
598 	if (name == NULL)
599 		return;
600 	for (j = KT_MIN; j <= KT_MAX; j *= 2) {
601 		if (get_keytypes & j) {
602 			while (ncon >= MAXCON)
603 				conloop();
604 			conalloc(name, *host ? host : name, j);
605 		}
606 	}
607 }
608 
609 void
610 fatal(const char *fmt,...)
611 {
612 	va_list args;
613 
614 	va_start(args, fmt);
615 	do_log(SYSLOG_LEVEL_FATAL, fmt, args);
616 	va_end(args);
617 	exit(255);
618 }
619 
620 static void
621 usage(void)
622 {
623 	fprintf(stderr,
624 	    "usage: %s [-46cHv] [-f file] [-p port] [-T timeout] [-t type]\n"
625 	    "\t\t   [host | addrlist namelist] ...\n",
626 	    __progname);
627 	exit(1);
628 }
629 
630 int
631 main(int argc, char **argv)
632 {
633 	int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
634 	int opt, fopt_count = 0, j;
635 	char *tname, *cp, line[NI_MAXHOST];
636 	FILE *fp;
637 	u_long linenum;
638 
639 	extern int optind;
640 	extern char *optarg;
641 
642 	ssh_malloc_init();	/* must be called before any mallocs */
643 	__progname = ssh_get_progname(argv[0]);
644 	seed_rng();
645 	TAILQ_INIT(&tq);
646 
647 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
648 	sanitise_stdfd();
649 
650 	if (argc <= 1)
651 		usage();
652 
653 	while ((opt = getopt(argc, argv, "cHv46p:T:t:f:")) != -1) {
654 		switch (opt) {
655 		case 'H':
656 			hash_hosts = 1;
657 			break;
658 		case 'c':
659 			get_cert = 1;
660 			break;
661 		case 'p':
662 			ssh_port = a2port(optarg);
663 			if (ssh_port <= 0) {
664 				fprintf(stderr, "Bad port '%s'\n", optarg);
665 				exit(1);
666 			}
667 			break;
668 		case 'T':
669 			timeout = convtime(optarg);
670 			if (timeout == -1 || timeout == 0) {
671 				fprintf(stderr, "Bad timeout '%s'\n", optarg);
672 				usage();
673 			}
674 			break;
675 		case 'v':
676 			if (!debug_flag) {
677 				debug_flag = 1;
678 				log_level = SYSLOG_LEVEL_DEBUG1;
679 			}
680 			else if (log_level < SYSLOG_LEVEL_DEBUG3)
681 				log_level++;
682 			else
683 				fatal("Too high debugging level.");
684 			break;
685 		case 'f':
686 			if (strcmp(optarg, "-") == 0)
687 				optarg = NULL;
688 			argv[fopt_count++] = optarg;
689 			break;
690 		case 't':
691 			get_keytypes = 0;
692 			tname = strtok(optarg, ",");
693 			while (tname) {
694 				int type = sshkey_type_from_name(tname);
695 
696 				switch (type) {
697 				case KEY_DSA:
698 					get_keytypes |= KT_DSA;
699 					break;
700 				case KEY_ECDSA:
701 					get_keytypes |= KT_ECDSA;
702 					break;
703 				case KEY_RSA:
704 					get_keytypes |= KT_RSA;
705 					break;
706 				case KEY_ED25519:
707 					get_keytypes |= KT_ED25519;
708 					break;
709 				case KEY_UNSPEC:
710 				default:
711 					fatal("Unknown key type \"%s\"", tname);
712 				}
713 				tname = strtok(NULL, ",");
714 			}
715 			break;
716 		case '4':
717 			IPv4or6 = AF_INET;
718 			break;
719 		case '6':
720 			IPv4or6 = AF_INET6;
721 			break;
722 		case '?':
723 		default:
724 			usage();
725 		}
726 	}
727 	if (optind == argc && !fopt_count)
728 		usage();
729 
730 	log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1);
731 
732 	maxfd = fdlim_get(1);
733 	if (maxfd < 0)
734 		fatal("%s: fdlim_get: bad value", __progname);
735 	if (maxfd > MAXMAXFD)
736 		maxfd = MAXMAXFD;
737 	if (MAXCON <= 0)
738 		fatal("%s: not enough file descriptors", __progname);
739 	if (maxfd > fdlim_get(0))
740 		fdlim_set(maxfd);
741 	fdcon = xcalloc(maxfd, sizeof(con));
742 
743 	read_wait_nfdset = howmany(maxfd, NFDBITS);
744 	read_wait = xcalloc(read_wait_nfdset, sizeof(fd_mask));
745 
746 	for (j = 0; j < fopt_count; j++) {
747 		if (argv[j] == NULL)
748 			fp = stdin;
749 		else if ((fp = fopen(argv[j], "r")) == NULL)
750 			fatal("%s: %s: %s", __progname, argv[j],
751 			    strerror(errno));
752 		linenum = 0;
753 
754 		while (read_keyfile_line(fp,
755 		    argv[j] == NULL ? "(stdin)" : argv[j], line, sizeof(line),
756 		    &linenum) != -1) {
757 			/* Chomp off trailing whitespace and comments */
758 			if ((cp = strchr(line, '#')) == NULL)
759 				cp = line + strlen(line) - 1;
760 			while (cp >= line) {
761 				if (*cp == ' ' || *cp == '\t' ||
762 				    *cp == '\n' || *cp == '#')
763 					*cp-- = '\0';
764 				else
765 					break;
766 			}
767 
768 			/* Skip empty lines */
769 			if (*line == '\0')
770 				continue;
771 
772 			do_host(line);
773 		}
774 
775 		if (ferror(fp))
776 			fatal("%s: %s: %s", __progname, argv[j],
777 			    strerror(errno));
778 
779 		fclose(fp);
780 	}
781 
782 	while (optind < argc)
783 		do_host(argv[optind++]);
784 
785 	while (ncon > 0)
786 		conloop();
787 
788 	return (0);
789 }
790