xref: /openbsd-src/usr.bin/ssh/ssh-keyscan.c (revision f84b1df5a16cdd762c93854218de246e79975d3b) 
1 /* $OpenBSD: ssh-keyscan.c,v 1.145 2022/01/21 00:53:40 deraadt 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 <sys/types.h>
11 #include <sys/socket.h>
12 #include <sys/queue.h>
13 #include <sys/time.h>
14 #include <sys/resource.h>
15 
16 #ifdef WITH_OPENSSL
17 #include <openssl/bn.h>
18 #endif
19 
20 #include <errno.h>
21 #include <netdb.h>
22 #include <stdarg.h>
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <poll.h>
26 #include <signal.h>
27 #include <string.h>
28 #include <unistd.h>
29 
30 #include "xmalloc.h"
31 #include "ssh.h"
32 #include "sshbuf.h"
33 #include "sshkey.h"
34 #include "cipher.h"
35 #include "kex.h"
36 #include "compat.h"
37 #include "myproposal.h"
38 #include "packet.h"
39 #include "dispatch.h"
40 #include "log.h"
41 #include "atomicio.h"
42 #include "misc.h"
43 #include "hostfile.h"
44 #include "ssherr.h"
45 #include "ssh_api.h"
46 #include "dns.h"
47 
48 /* Flag indicating whether IPv4 or IPv6.  This can be set on the command line.
49    Default value is AF_UNSPEC means both IPv4 and IPv6. */
50 int IPv4or6 = AF_UNSPEC;
51 
52 int ssh_port = SSH_DEFAULT_PORT;
53 
54 #define KT_DSA		(1)
55 #define KT_RSA		(1<<1)
56 #define KT_ECDSA	(1<<2)
57 #define KT_ED25519	(1<<3)
58 #define KT_XMSS		(1<<4)
59 #define KT_ECDSA_SK	(1<<5)
60 #define KT_ED25519_SK	(1<<6)
61 
62 #define KT_MIN		KT_DSA
63 #define KT_MAX		KT_ED25519_SK
64 
65 int get_cert = 0;
66 int get_keytypes = KT_RSA|KT_ECDSA|KT_ED25519|KT_ECDSA_SK|KT_ED25519_SK;
67 
68 int hash_hosts = 0;		/* Hash hostname on output */
69 
70 int print_sshfp = 0;		/* Print SSHFP records instead of known_hosts */
71 
72 int found_one = 0;		/* Successfully found a key */
73 
74 #define MAXMAXFD 256
75 
76 /* The number of seconds after which to give up on a TCP connection */
77 int timeout = 5;
78 
79 int maxfd;
80 #define MAXCON (maxfd - 10)
81 
82 extern char *__progname;
83 struct pollfd *read_wait;
84 int ncon;
85 
86 /*
87  * Keep a connection structure for each file descriptor.  The state
88  * associated with file descriptor n is held in fdcon[n].
89  */
90 typedef struct Connection {
91 	u_char c_status;	/* State of connection on this file desc. */
92 #define CS_UNUSED 0		/* File descriptor unused */
93 #define CS_CON 1		/* Waiting to connect/read greeting */
94 #define CS_SIZE 2		/* Waiting to read initial packet size */
95 #define CS_KEYS 3		/* Waiting to read public key packet */
96 	int c_fd;		/* Quick lookup: c->c_fd == c - fdcon */
97 	int c_plen;		/* Packet length field for ssh packet */
98 	int c_len;		/* Total bytes which must be read. */
99 	int c_off;		/* Length of data read so far. */
100 	int c_keytype;		/* Only one of KT_* */
101 	sig_atomic_t c_done;	/* SSH2 done */
102 	char *c_namebase;	/* Address to free for c_name and c_namelist */
103 	char *c_name;		/* Hostname of connection for errors */
104 	char *c_namelist;	/* Pointer to other possible addresses */
105 	char *c_output_name;	/* Hostname of connection for output */
106 	char *c_data;		/* Data read from this fd */
107 	struct ssh *c_ssh;	/* SSH-connection */
108 	struct timespec c_ts;	/* Time at which connection gets aborted */
109 	TAILQ_ENTRY(Connection) c_link;	/* List of connections in timeout order. */
110 } con;
111 
112 TAILQ_HEAD(conlist, Connection) tq;	/* Timeout Queue */
113 con *fdcon;
114 
115 static void keyprint(con *c, struct sshkey *key);
116 
117 static int
118 fdlim_get(int hard)
119 {
120 	struct rlimit rlfd;
121 
122 	if (getrlimit(RLIMIT_NOFILE, &rlfd) == -1)
123 		return (-1);
124 	if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY)
125 		return sysconf(_SC_OPEN_MAX);
126 	else
127 		return hard ? rlfd.rlim_max : rlfd.rlim_cur;
128 }
129 
130 static int
131 fdlim_set(int lim)
132 {
133 	struct rlimit rlfd;
134 
135 	if (lim <= 0)
136 		return (-1);
137 	if (getrlimit(RLIMIT_NOFILE, &rlfd) == -1)
138 		return (-1);
139 	rlfd.rlim_cur = lim;
140 	if (setrlimit(RLIMIT_NOFILE, &rlfd) == -1)
141 		return (-1);
142 	return (0);
143 }
144 
145 /*
146  * This is an strsep function that returns a null field for adjacent
147  * separators.  This is the same as the 4.4BSD strsep, but different from the
148  * one in the GNU libc.
149  */
150 static char *
151 xstrsep(char **str, const char *delim)
152 {
153 	char *s, *e;
154 
155 	if (!**str)
156 		return (NULL);
157 
158 	s = *str;
159 	e = s + strcspn(s, delim);
160 
161 	if (*e != '\0')
162 		*e++ = '\0';
163 	*str = e;
164 
165 	return (s);
166 }
167 
168 /*
169  * Get the next non-null token (like GNU strsep).  Strsep() will return a
170  * null token for two adjacent separators, so we may have to loop.
171  */
172 static char *
173 strnnsep(char **stringp, char *delim)
174 {
175 	char *tok;
176 
177 	do {
178 		tok = xstrsep(stringp, delim);
179 	} while (tok && *tok == '\0');
180 	return (tok);
181 }
182 
183 
184 static int
185 key_print_wrapper(struct sshkey *hostkey, struct ssh *ssh)
186 {
187 	con *c;
188 
189 	if ((c = ssh_get_app_data(ssh)) != NULL)
190 		keyprint(c, hostkey);
191 	/* always abort key exchange */
192 	return -1;
193 }
194 
195 static int
196 ssh2_capable(int remote_major, int remote_minor)
197 {
198 	switch (remote_major) {
199 	case 1:
200 		if (remote_minor == 99)
201 			return 1;
202 		break;
203 	case 2:
204 		return 1;
205 	default:
206 		break;
207 	}
208 	return 0;
209 }
210 
211 static void
212 keygrab_ssh2(con *c)
213 {
214 	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
215 	int r;
216 
217 	switch (c->c_keytype) {
218 	case KT_DSA:
219 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
220 		    "ssh-dss-cert-v01@openssh.com" : "ssh-dss";
221 		break;
222 	case KT_RSA:
223 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
224 		    "rsa-sha2-512-cert-v01@openssh.com,"
225 		    "rsa-sha2-256-cert-v01@openssh.com,"
226 		    "ssh-rsa-cert-v01@openssh.com" :
227 		    "rsa-sha2-512,"
228 		    "rsa-sha2-256,"
229 		    "ssh-rsa";
230 		break;
231 	case KT_ED25519:
232 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
233 		    "ssh-ed25519-cert-v01@openssh.com" : "ssh-ed25519";
234 		break;
235 	case KT_XMSS:
236 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
237 		    "ssh-xmss-cert-v01@openssh.com" : "ssh-xmss@openssh.com";
238 		break;
239 	case KT_ECDSA:
240 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
241 		    "ecdsa-sha2-nistp256-cert-v01@openssh.com,"
242 		    "ecdsa-sha2-nistp384-cert-v01@openssh.com,"
243 		    "ecdsa-sha2-nistp521-cert-v01@openssh.com" :
244 		    "ecdsa-sha2-nistp256,"
245 		    "ecdsa-sha2-nistp384,"
246 		    "ecdsa-sha2-nistp521";
247 		break;
248 	case KT_ECDSA_SK:
249 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
250 		    "sk-ecdsa-sha2-nistp256-cert-v01@openssh.com" :
251 		    "sk-ecdsa-sha2-nistp256@openssh.com";
252 		break;
253 	case KT_ED25519_SK:
254 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
255 		    "sk-ssh-ed25519-cert-v01@openssh.com" :
256 		    "sk-ssh-ed25519@openssh.com";
257 		break;
258 	default:
259 		fatal("unknown key type %d", c->c_keytype);
260 		break;
261 	}
262 	if ((r = kex_setup(c->c_ssh, myproposal)) != 0) {
263 		free(c->c_ssh);
264 		fprintf(stderr, "kex_setup: %s\n", ssh_err(r));
265 		exit(1);
266 	}
267 #ifdef WITH_OPENSSL
268 	c->c_ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client;
269 	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client;
270 	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client;
271 	c->c_ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client;
272 	c->c_ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client;
273 	c->c_ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
274 	c->c_ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
275 	c->c_ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
276 #endif
277 	c->c_ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
278 	c->c_ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client;
279 	ssh_set_verify_host_key_callback(c->c_ssh, key_print_wrapper);
280 	/*
281 	 * do the key-exchange until an error occurs or until
282 	 * the key_print_wrapper() callback sets c_done.
283 	 */
284 	ssh_dispatch_run(c->c_ssh, DISPATCH_BLOCK, &c->c_done);
285 }
286 
287 static void
288 keyprint_one(const char *host, struct sshkey *key)
289 {
290 	char *hostport = NULL, *hashed = NULL;
291 	const char *known_host;
292 
293 	found_one = 1;
294 
295 	if (print_sshfp) {
296 		export_dns_rr(host, key, stdout, 0);
297 		return;
298 	}
299 
300 	hostport = put_host_port(host, ssh_port);
301 	lowercase(hostport);
302 	if (hash_hosts && (hashed = host_hash(hostport, NULL, 0)) == NULL)
303 		fatal("host_hash failed");
304 	known_host = hash_hosts ? hashed : hostport;
305 	if (!get_cert)
306 		fprintf(stdout, "%s ", known_host);
307 	sshkey_write(key, stdout);
308 	fputs("\n", stdout);
309 	free(hashed);
310 	free(hostport);
311 }
312 
313 static void
314 keyprint(con *c, struct sshkey *key)
315 {
316 	char *hosts = c->c_output_name ? c->c_output_name : c->c_name;
317 	char *host, *ohosts;
318 
319 	if (key == NULL)
320 		return;
321 	if (get_cert || (!hash_hosts && ssh_port == SSH_DEFAULT_PORT)) {
322 		keyprint_one(hosts, key);
323 		return;
324 	}
325 	ohosts = hosts = xstrdup(hosts);
326 	while ((host = strsep(&hosts, ",")) != NULL)
327 		keyprint_one(host, key);
328 	free(ohosts);
329 }
330 
331 static int
332 tcpconnect(char *host)
333 {
334 	struct addrinfo hints, *ai, *aitop;
335 	char strport[NI_MAXSERV];
336 	int gaierr, s = -1;
337 
338 	snprintf(strport, sizeof strport, "%d", ssh_port);
339 	memset(&hints, 0, sizeof(hints));
340 	hints.ai_family = IPv4or6;
341 	hints.ai_socktype = SOCK_STREAM;
342 	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
343 		error("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr));
344 		return -1;
345 	}
346 	for (ai = aitop; ai; ai = ai->ai_next) {
347 		s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
348 		if (s == -1) {
349 			error("socket: %s", strerror(errno));
350 			continue;
351 		}
352 		if (set_nonblock(s) == -1)
353 			fatal_f("set_nonblock(%d)", s);
354 		if (connect(s, ai->ai_addr, ai->ai_addrlen) == -1 &&
355 		    errno != EINPROGRESS)
356 			error("connect (`%s'): %s", host, strerror(errno));
357 		else
358 			break;
359 		close(s);
360 		s = -1;
361 	}
362 	freeaddrinfo(aitop);
363 	return s;
364 }
365 
366 static int
367 conalloc(char *iname, char *oname, int keytype)
368 {
369 	char *namebase, *name, *namelist;
370 	int s;
371 
372 	namebase = namelist = xstrdup(iname);
373 
374 	do {
375 		name = xstrsep(&namelist, ",");
376 		if (!name) {
377 			free(namebase);
378 			return (-1);
379 		}
380 	} while ((s = tcpconnect(name)) < 0);
381 
382 	if (s >= maxfd)
383 		fatal("conalloc: fdno %d too high", s);
384 	if (fdcon[s].c_status)
385 		fatal("conalloc: attempt to reuse fdno %d", s);
386 
387 	debug3_f("oname %s kt %d", oname, keytype);
388 	fdcon[s].c_fd = s;
389 	fdcon[s].c_status = CS_CON;
390 	fdcon[s].c_namebase = namebase;
391 	fdcon[s].c_name = name;
392 	fdcon[s].c_namelist = namelist;
393 	fdcon[s].c_output_name = xstrdup(oname);
394 	fdcon[s].c_data = (char *) &fdcon[s].c_plen;
395 	fdcon[s].c_len = 4;
396 	fdcon[s].c_off = 0;
397 	fdcon[s].c_keytype = keytype;
398 	monotime_ts(&fdcon[s].c_ts);
399 	fdcon[s].c_ts.tv_sec += timeout;
400 	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
401 	read_wait[s].fd = s;
402 	read_wait[s].events = POLLIN;
403 	ncon++;
404 	return (s);
405 }
406 
407 static void
408 confree(int s)
409 {
410 	if (s >= maxfd || fdcon[s].c_status == CS_UNUSED)
411 		fatal("confree: attempt to free bad fdno %d", s);
412 	free(fdcon[s].c_namebase);
413 	free(fdcon[s].c_output_name);
414 	if (fdcon[s].c_status == CS_KEYS)
415 		free(fdcon[s].c_data);
416 	fdcon[s].c_status = CS_UNUSED;
417 	fdcon[s].c_keytype = 0;
418 	if (fdcon[s].c_ssh) {
419 		ssh_packet_close(fdcon[s].c_ssh);
420 		free(fdcon[s].c_ssh);
421 		fdcon[s].c_ssh = NULL;
422 	} else
423 		close(s);
424 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
425 	read_wait[s].fd = -1;
426 	read_wait[s].events = 0;
427 	ncon--;
428 }
429 
430 static void
431 contouch(int s)
432 {
433 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
434 	monotime_ts(&fdcon[s].c_ts);
435 	fdcon[s].c_ts.tv_sec += timeout;
436 	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
437 }
438 
439 static int
440 conrecycle(int s)
441 {
442 	con *c = &fdcon[s];
443 	int ret;
444 
445 	ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
446 	confree(s);
447 	return (ret);
448 }
449 
450 static void
451 congreet(int s)
452 {
453 	int n = 0, remote_major = 0, remote_minor = 0;
454 	char buf[256], *cp;
455 	char remote_version[sizeof buf];
456 	size_t bufsiz;
457 	con *c = &fdcon[s];
458 
459 	/* send client banner */
460 	n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
461 	    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2);
462 	if (n < 0 || (size_t)n >= sizeof(buf)) {
463 		error("snprintf: buffer too small");
464 		confree(s);
465 		return;
466 	}
467 	if (atomicio(vwrite, s, buf, n) != (size_t)n) {
468 		error("write (%s): %s", c->c_name, strerror(errno));
469 		confree(s);
470 		return;
471 	}
472 
473 	for (;;) {
474 		memset(buf, '\0', sizeof(buf));
475 		bufsiz = sizeof(buf);
476 		cp = buf;
477 		while (bufsiz-- &&
478 		    (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') {
479 			if (*cp == '\r')
480 				*cp = '\n';
481 			cp++;
482 		}
483 		if (n != 1 || strncmp(buf, "SSH-", 4) == 0)
484 			break;
485 	}
486 	if (n == 0) {
487 		switch (errno) {
488 		case EPIPE:
489 			error("%s: Connection closed by remote host", c->c_name);
490 			break;
491 		case ECONNREFUSED:
492 			break;
493 		default:
494 			error("read (%s): %s", c->c_name, strerror(errno));
495 			break;
496 		}
497 		conrecycle(s);
498 		return;
499 	}
500 	if (*cp != '\n' && *cp != '\r') {
501 		error("%s: bad greeting", c->c_name);
502 		confree(s);
503 		return;
504 	}
505 	*cp = '\0';
506 	if ((c->c_ssh = ssh_packet_set_connection(NULL, s, s)) == NULL)
507 		fatal("ssh_packet_set_connection failed");
508 	ssh_packet_set_timeout(c->c_ssh, timeout, 1);
509 	ssh_set_app_data(c->c_ssh, c);	/* back link */
510 	c->c_ssh->compat = 0;
511 	if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
512 	    &remote_major, &remote_minor, remote_version) == 3)
513 		compat_banner(c->c_ssh, remote_version);
514 	if (!ssh2_capable(remote_major, remote_minor)) {
515 		debug("%s doesn't support ssh2", c->c_name);
516 		confree(s);
517 		return;
518 	}
519 	fprintf(stderr, "%c %s:%d %s\n", print_sshfp ? ';' : '#',
520 	    c->c_name, ssh_port, chop(buf));
521 	keygrab_ssh2(c);
522 	confree(s);
523 }
524 
525 static void
526 conread(int s)
527 {
528 	con *c = &fdcon[s];
529 	size_t n;
530 
531 	if (c->c_status == CS_CON) {
532 		congreet(s);
533 		return;
534 	}
535 	n = atomicio(read, s, c->c_data + c->c_off, c->c_len - c->c_off);
536 	if (n == 0) {
537 		error("read (%s): %s", c->c_name, strerror(errno));
538 		confree(s);
539 		return;
540 	}
541 	c->c_off += n;
542 
543 	if (c->c_off == c->c_len)
544 		switch (c->c_status) {
545 		case CS_SIZE:
546 			c->c_plen = htonl(c->c_plen);
547 			c->c_len = c->c_plen + 8 - (c->c_plen & 7);
548 			c->c_off = 0;
549 			c->c_data = xmalloc(c->c_len);
550 			c->c_status = CS_KEYS;
551 			break;
552 		default:
553 			fatal("conread: invalid status %d", c->c_status);
554 			break;
555 		}
556 
557 	contouch(s);
558 }
559 
560 static void
561 conloop(void)
562 {
563 	struct timespec seltime, now;
564 	con *c;
565 	int i;
566 
567 	monotime_ts(&now);
568 	c = TAILQ_FIRST(&tq);
569 
570 	if (c && timespeccmp(&c->c_ts, &now, >))
571 		timespecsub(&c->c_ts, &now, &seltime);
572 	else
573 		timespecclear(&seltime);
574 
575 	while (ppoll(read_wait, maxfd, &seltime, NULL) == -1) {
576 		if (errno == EAGAIN || errno == EINTR)
577 			continue;
578 		error("poll error");
579 	}
580 
581 	for (i = 0; i < maxfd; i++) {
582 		if (read_wait[i].revents & (POLLHUP|POLLERR|POLLNVAL))
583 			confree(i);
584 		else if (read_wait[i].revents & (POLLIN|POLLHUP))
585 			conread(i);
586 	}
587 
588 	c = TAILQ_FIRST(&tq);
589 	while (c && timespeccmp(&c->c_ts, &now, <)) {
590 		int s = c->c_fd;
591 
592 		c = TAILQ_NEXT(c, c_link);
593 		conrecycle(s);
594 	}
595 }
596 
597 static void
598 do_host(char *host)
599 {
600 	char *name = strnnsep(&host, " \t\n");
601 	int j;
602 
603 	if (name == NULL)
604 		return;
605 	for (j = KT_MIN; j <= KT_MAX; j *= 2) {
606 		if (get_keytypes & j) {
607 			while (ncon >= MAXCON)
608 				conloop();
609 			conalloc(name, *host ? host : name, j);
610 		}
611 	}
612 }
613 
614 void
615 sshfatal(const char *file, const char *func, int line, int showfunc,
616     LogLevel level, const char *suffix, const char *fmt, ...)
617 {
618 	va_list args;
619 
620 	va_start(args, fmt);
621 	sshlogv(file, func, line, showfunc, level, suffix, fmt, args);
622 	va_end(args);
623 	cleanup_exit(255);
624 }
625 
626 static void
627 usage(void)
628 {
629 	fprintf(stderr,
630 	    "usage: %s [-46cDHv] [-f file] [-p port] [-T timeout] [-t type]\n"
631 	    "\t\t   [host | addrlist namelist]\n",
632 	    __progname);
633 	exit(1);
634 }
635 
636 int
637 main(int argc, char **argv)
638 {
639 	int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
640 	int opt, fopt_count = 0, j;
641 	char *tname, *cp, *line = NULL;
642 	size_t linesize = 0;
643 	FILE *fp;
644 
645 	extern int optind;
646 	extern char *optarg;
647 
648 	TAILQ_INIT(&tq);
649 
650 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
651 	sanitise_stdfd();
652 
653 	if (argc <= 1)
654 		usage();
655 
656 	while ((opt = getopt(argc, argv, "cDHv46p:T:t:f:")) != -1) {
657 		switch (opt) {
658 		case 'H':
659 			hash_hosts = 1;
660 			break;
661 		case 'c':
662 			get_cert = 1;
663 			break;
664 		case 'D':
665 			print_sshfp = 1;
666 			break;
667 		case 'p':
668 			ssh_port = a2port(optarg);
669 			if (ssh_port <= 0) {
670 				fprintf(stderr, "Bad port '%s'\n", optarg);
671 				exit(1);
672 			}
673 			break;
674 		case 'T':
675 			timeout = convtime(optarg);
676 			if (timeout == -1 || timeout == 0) {
677 				fprintf(stderr, "Bad timeout '%s'\n", optarg);
678 				usage();
679 			}
680 			break;
681 		case 'v':
682 			if (!debug_flag) {
683 				debug_flag = 1;
684 				log_level = SYSLOG_LEVEL_DEBUG1;
685 			}
686 			else if (log_level < SYSLOG_LEVEL_DEBUG3)
687 				log_level++;
688 			else
689 				fatal("Too high debugging level.");
690 			break;
691 		case 'f':
692 			if (strcmp(optarg, "-") == 0)
693 				optarg = NULL;
694 			argv[fopt_count++] = optarg;
695 			break;
696 		case 't':
697 			get_keytypes = 0;
698 			tname = strtok(optarg, ",");
699 			while (tname) {
700 				int type = sshkey_type_from_name(tname);
701 
702 				switch (type) {
703 				case KEY_DSA:
704 					get_keytypes |= KT_DSA;
705 					break;
706 				case KEY_ECDSA:
707 					get_keytypes |= KT_ECDSA;
708 					break;
709 				case KEY_RSA:
710 					get_keytypes |= KT_RSA;
711 					break;
712 				case KEY_ED25519:
713 					get_keytypes |= KT_ED25519;
714 					break;
715 				case KEY_XMSS:
716 					get_keytypes |= KT_XMSS;
717 					break;
718 				case KEY_ED25519_SK:
719 					get_keytypes |= KT_ED25519_SK;
720 					break;
721 				case KEY_ECDSA_SK:
722 					get_keytypes |= KT_ECDSA_SK;
723 					break;
724 				case KEY_UNSPEC:
725 				default:
726 					fatal("Unknown key type \"%s\"", tname);
727 				}
728 				tname = strtok(NULL, ",");
729 			}
730 			break;
731 		case '4':
732 			IPv4or6 = AF_INET;
733 			break;
734 		case '6':
735 			IPv4or6 = AF_INET6;
736 			break;
737 		case '?':
738 		default:
739 			usage();
740 		}
741 	}
742 	if (optind == argc && !fopt_count)
743 		usage();
744 
745 	log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1);
746 
747 	maxfd = fdlim_get(1);
748 	if (maxfd < 0)
749 		fatal("%s: fdlim_get: bad value", __progname);
750 	if (maxfd > MAXMAXFD)
751 		maxfd = MAXMAXFD;
752 	if (MAXCON <= 0)
753 		fatal("%s: not enough file descriptors", __progname);
754 	if (maxfd > fdlim_get(0))
755 		fdlim_set(maxfd);
756 	fdcon = xcalloc(maxfd, sizeof(con));
757 	read_wait = xcalloc(maxfd, sizeof(struct pollfd));
758 	for (j = 0; j < maxfd; j++)
759 		read_wait[j].fd = -1;
760 
761 	for (j = 0; j < fopt_count; j++) {
762 		if (argv[j] == NULL)
763 			fp = stdin;
764 		else if ((fp = fopen(argv[j], "r")) == NULL)
765 			fatal("%s: %s: %s", __progname, argv[j], strerror(errno));
766 
767 		while (getline(&line, &linesize, fp) != -1) {
768 			/* Chomp off trailing whitespace and comments */
769 			if ((cp = strchr(line, '#')) == NULL)
770 				cp = line + strlen(line) - 1;
771 			while (cp >= line) {
772 				if (*cp == ' ' || *cp == '\t' ||
773 				    *cp == '\n' || *cp == '#')
774 					*cp-- = '\0';
775 				else
776 					break;
777 			}
778 
779 			/* Skip empty lines */
780 			if (*line == '\0')
781 				continue;
782 
783 			do_host(line);
784 		}
785 
786 		if (ferror(fp))
787 			fatal("%s: %s: %s", __progname, argv[j], strerror(errno));
788 
789 		fclose(fp);
790 	}
791 	free(line);
792 
793 	while (optind < argc)
794 		do_host(argv[optind++]);
795 
796 	while (ncon > 0)
797 		conloop();
798 
799 	return found_one ? 0 : 1;
800 }
801