xref: /openbsd/usr.bin/ssh/ssh-keyscan.c (revision 28a658e2)
1 /* $OpenBSD: ssh-keyscan.c,v 1.164 2024/10/18 05:32:51 djm 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 <limits.h>
22 #include <netdb.h>
23 #include <stdarg.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <poll.h>
27 #include <signal.h>
28 #include <string.h>
29 #include <unistd.h>
30 
31 #include "xmalloc.h"
32 #include "ssh.h"
33 #include "sshbuf.h"
34 #include "sshkey.h"
35 #include "cipher.h"
36 #include "digest.h"
37 #include "kex.h"
38 #include "compat.h"
39 #include "myproposal.h"
40 #include "packet.h"
41 #include "dispatch.h"
42 #include "log.h"
43 #include "atomicio.h"
44 #include "misc.h"
45 #include "hostfile.h"
46 #include "ssherr.h"
47 #include "ssh_api.h"
48 #include "dns.h"
49 #include "addr.h"
50 
51 /* Flag indicating whether IPv4 or IPv6.  This can be set on the command line.
52    Default value is AF_UNSPEC means both IPv4 and IPv6. */
53 int IPv4or6 = AF_UNSPEC;
54 
55 int ssh_port = SSH_DEFAULT_PORT;
56 
57 #define KT_DSA		(1)
58 #define KT_RSA		(1<<1)
59 #define KT_ECDSA	(1<<2)
60 #define KT_ED25519	(1<<3)
61 #define KT_XMSS		(1<<4)
62 #define KT_ECDSA_SK	(1<<5)
63 #define KT_ED25519_SK	(1<<6)
64 
65 #define KT_MIN		KT_DSA
66 #define KT_MAX		KT_ED25519_SK
67 
68 int get_cert = 0;
69 int get_keytypes = KT_RSA|KT_ECDSA|KT_ED25519|KT_ECDSA_SK|KT_ED25519_SK;
70 
71 int hash_hosts = 0;		/* Hash hostname on output */
72 
73 int print_sshfp = 0;		/* Print SSHFP records instead of known_hosts */
74 
75 int found_one = 0;		/* Successfully found a key */
76 
77 int hashalg = -1;		/* Hash for SSHFP records or -1 for all */
78 
79 int quiet = 0;			/* Don't print key comment lines */
80 
81 #define MAXMAXFD 256
82 
83 /* The number of seconds after which to give up on a TCP connection */
84 int timeout = 5;
85 
86 int maxfd;
87 #define MAXCON (maxfd - 10)
88 
89 extern char *__progname;
90 struct pollfd *read_wait;
91 int ncon;
92 
93 /*
94  * Keep a connection structure for each file descriptor.  The state
95  * associated with file descriptor n is held in fdcon[n].
96  */
97 typedef struct Connection {
98 	u_char c_status;	/* State of connection on this file desc. */
99 #define CS_UNUSED 0		/* File descriptor unused */
100 #define CS_CON 1		/* Waiting to connect/read greeting */
101 	int c_fd;		/* Quick lookup: c->c_fd == c - fdcon */
102 	int c_keytype;		/* Only one of KT_* */
103 	sig_atomic_t c_done;	/* SSH2 done */
104 	char *c_namebase;	/* Address to free for c_name and c_namelist */
105 	char *c_name;		/* Hostname of connection for errors */
106 	char *c_namelist;	/* Pointer to other possible addresses */
107 	char *c_output_name;	/* Hostname of connection for output */
108 	struct ssh *c_ssh;	/* SSH-connection */
109 	struct timespec c_ts;	/* Time at which connection gets aborted */
110 	TAILQ_ENTRY(Connection) c_link;	/* List of connections in timeout order. */
111 } con;
112 
113 TAILQ_HEAD(conlist, Connection) tq;	/* Timeout Queue */
114 con *fdcon;
115 
116 static void keyprint(con *c, struct sshkey *key);
117 
118 static int
fdlim_get(int hard)119 fdlim_get(int hard)
120 {
121 	struct rlimit rlfd;
122 
123 	if (getrlimit(RLIMIT_NOFILE, &rlfd) == -1)
124 		return (-1);
125 	if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY ||
126 	    (hard ? rlfd.rlim_max : rlfd.rlim_cur) > INT_MAX)
127 		return sysconf(_SC_OPEN_MAX);
128 	return hard ? rlfd.rlim_max : rlfd.rlim_cur;
129 }
130 
131 static int
fdlim_set(int lim)132 fdlim_set(int lim)
133 {
134 	struct rlimit rlfd;
135 
136 	if (lim <= 0)
137 		return (-1);
138 	if (getrlimit(RLIMIT_NOFILE, &rlfd) == -1)
139 		return (-1);
140 	rlfd.rlim_cur = lim;
141 	if (setrlimit(RLIMIT_NOFILE, &rlfd) == -1)
142 		return (-1);
143 	return (0);
144 }
145 
146 /*
147  * This is an strsep function that returns a null field for adjacent
148  * separators.  This is the same as the 4.4BSD strsep, but different from the
149  * one in the GNU libc.
150  */
151 static char *
xstrsep(char ** str,const char * delim)152 xstrsep(char **str, const char *delim)
153 {
154 	char *s, *e;
155 
156 	if (!**str)
157 		return (NULL);
158 
159 	s = *str;
160 	e = s + strcspn(s, delim);
161 
162 	if (*e != '\0')
163 		*e++ = '\0';
164 	*str = e;
165 
166 	return (s);
167 }
168 
169 /*
170  * Get the next non-null token (like GNU strsep).  Strsep() will return a
171  * null token for two adjacent separators, so we may have to loop.
172  */
173 static char *
strnnsep(char ** stringp,char * delim)174 strnnsep(char **stringp, char *delim)
175 {
176 	char *tok;
177 
178 	do {
179 		tok = xstrsep(stringp, delim);
180 	} while (tok && *tok == '\0');
181 	return (tok);
182 }
183 
184 
185 static int
key_print_wrapper(struct sshkey * hostkey,struct ssh * ssh)186 key_print_wrapper(struct sshkey *hostkey, struct ssh *ssh)
187 {
188 	con *c;
189 
190 	if ((c = ssh_get_app_data(ssh)) != NULL)
191 		keyprint(c, hostkey);
192 	/* always abort key exchange */
193 	return -1;
194 }
195 
196 static int
ssh2_capable(int remote_major,int remote_minor)197 ssh2_capable(int remote_major, int remote_minor)
198 {
199 	switch (remote_major) {
200 	case 1:
201 		if (remote_minor == 99)
202 			return 1;
203 		break;
204 	case 2:
205 		return 1;
206 	default:
207 		break;
208 	}
209 	return 0;
210 }
211 
212 static void
keygrab_ssh2(con * c)213 keygrab_ssh2(con *c)
214 {
215 	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
216 	int r;
217 
218 	switch (c->c_keytype) {
219 	case KT_DSA:
220 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
221 		    "ssh-dss-cert-v01@openssh.com" : "ssh-dss";
222 		break;
223 	case KT_RSA:
224 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
225 		    "rsa-sha2-512-cert-v01@openssh.com,"
226 		    "rsa-sha2-256-cert-v01@openssh.com,"
227 		    "ssh-rsa-cert-v01@openssh.com" :
228 		    "rsa-sha2-512,"
229 		    "rsa-sha2-256,"
230 		    "ssh-rsa";
231 		break;
232 	case KT_ED25519:
233 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
234 		    "ssh-ed25519-cert-v01@openssh.com" : "ssh-ed25519";
235 		break;
236 	case KT_XMSS:
237 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
238 		    "ssh-xmss-cert-v01@openssh.com" : "ssh-xmss@openssh.com";
239 		break;
240 	case KT_ECDSA:
241 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
242 		    "ecdsa-sha2-nistp256-cert-v01@openssh.com,"
243 		    "ecdsa-sha2-nistp384-cert-v01@openssh.com,"
244 		    "ecdsa-sha2-nistp521-cert-v01@openssh.com" :
245 		    "ecdsa-sha2-nistp256,"
246 		    "ecdsa-sha2-nistp384,"
247 		    "ecdsa-sha2-nistp521";
248 		break;
249 	case KT_ECDSA_SK:
250 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
251 		    "sk-ecdsa-sha2-nistp256-cert-v01@openssh.com" :
252 		    "sk-ecdsa-sha2-nistp256@openssh.com";
253 		break;
254 	case KT_ED25519_SK:
255 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
256 		    "sk-ssh-ed25519-cert-v01@openssh.com" :
257 		    "sk-ssh-ed25519@openssh.com";
258 		break;
259 	default:
260 		fatal("unknown key type %d", c->c_keytype);
261 		break;
262 	}
263 	if ((r = kex_setup(c->c_ssh, myproposal)) != 0) {
264 		free(c->c_ssh);
265 		fprintf(stderr, "kex_setup: %s\n", ssh_err(r));
266 		exit(1);
267 	}
268 #ifdef WITH_OPENSSL
269 	c->c_ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client;
270 	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client;
271 	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client;
272 	c->c_ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client;
273 	c->c_ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client;
274 	c->c_ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
275 	c->c_ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
276 	c->c_ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
277 #endif
278 	c->c_ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
279 	c->c_ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client;
280 	c->c_ssh->kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_client;
281 	ssh_set_verify_host_key_callback(c->c_ssh, key_print_wrapper);
282 	/*
283 	 * do the key-exchange until an error occurs or until
284 	 * the key_print_wrapper() callback sets c_done.
285 	 */
286 	ssh_dispatch_run(c->c_ssh, DISPATCH_BLOCK, &c->c_done);
287 }
288 
289 static void
keyprint_one(const char * host,struct sshkey * key)290 keyprint_one(const char *host, struct sshkey *key)
291 {
292 	char *hostport = NULL, *hashed = NULL;
293 	const char *known_host;
294 	int r = 0;
295 
296 	found_one = 1;
297 
298 	if (print_sshfp) {
299 		export_dns_rr(host, key, stdout, 0, hashalg);
300 		return;
301 	}
302 
303 	hostport = put_host_port(host, ssh_port);
304 	lowercase(hostport);
305 	if (hash_hosts && (hashed = host_hash(hostport, NULL, 0)) == NULL)
306 		fatal("host_hash failed");
307 	known_host = hash_hosts ? hashed : hostport;
308 	if (!get_cert)
309 		r = fprintf(stdout, "%s ", known_host);
310 	if (r >= 0 && sshkey_write(key, stdout) == 0)
311 		(void)fputs("\n", stdout);
312 	free(hashed);
313 	free(hostport);
314 }
315 
316 static void
keyprint(con * c,struct sshkey * key)317 keyprint(con *c, struct sshkey *key)
318 {
319 	char *hosts = c->c_output_name ? c->c_output_name : c->c_name;
320 	char *host, *ohosts;
321 
322 	if (key == NULL)
323 		return;
324 	if (get_cert || (!hash_hosts && ssh_port == SSH_DEFAULT_PORT)) {
325 		keyprint_one(hosts, key);
326 		return;
327 	}
328 	ohosts = hosts = xstrdup(hosts);
329 	while ((host = strsep(&hosts, ",")) != NULL)
330 		keyprint_one(host, key);
331 	free(ohosts);
332 }
333 
334 static int
tcpconnect(char * host)335 tcpconnect(char *host)
336 {
337 	struct addrinfo hints, *ai, *aitop;
338 	char strport[NI_MAXSERV];
339 	int gaierr, s = -1;
340 
341 	snprintf(strport, sizeof strport, "%d", ssh_port);
342 	memset(&hints, 0, sizeof(hints));
343 	hints.ai_family = IPv4or6;
344 	hints.ai_socktype = SOCK_STREAM;
345 	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
346 		error("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr));
347 		return -1;
348 	}
349 	for (ai = aitop; ai; ai = ai->ai_next) {
350 		s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
351 		if (s == -1) {
352 			error("socket: %s", strerror(errno));
353 			continue;
354 		}
355 		if (set_nonblock(s) == -1)
356 			fatal_f("set_nonblock(%d)", s);
357 		if (connect(s, ai->ai_addr, ai->ai_addrlen) == -1 &&
358 		    errno != EINPROGRESS)
359 			error("connect (`%s'): %s", host, strerror(errno));
360 		else
361 			break;
362 		close(s);
363 		s = -1;
364 	}
365 	freeaddrinfo(aitop);
366 	return s;
367 }
368 
369 static int
conalloc(const char * iname,const char * oname,int keytype)370 conalloc(const char *iname, const char *oname, int keytype)
371 {
372 	char *namebase, *name, *namelist;
373 	int s;
374 
375 	namebase = namelist = xstrdup(iname);
376 
377 	do {
378 		name = xstrsep(&namelist, ",");
379 		if (!name) {
380 			free(namebase);
381 			return (-1);
382 		}
383 	} while ((s = tcpconnect(name)) < 0);
384 
385 	if (s >= maxfd)
386 		fatal("conalloc: fdno %d too high", s);
387 	if (fdcon[s].c_status)
388 		fatal("conalloc: attempt to reuse fdno %d", s);
389 
390 	debug3_f("oname %s kt %d", oname, keytype);
391 	fdcon[s].c_fd = s;
392 	fdcon[s].c_status = CS_CON;
393 	fdcon[s].c_namebase = namebase;
394 	fdcon[s].c_name = name;
395 	fdcon[s].c_namelist = namelist;
396 	fdcon[s].c_output_name = xstrdup(oname);
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
confree(int s)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 	fdcon[s].c_status = CS_UNUSED;
415 	fdcon[s].c_keytype = 0;
416 	if (fdcon[s].c_ssh) {
417 		ssh_packet_close(fdcon[s].c_ssh);
418 		free(fdcon[s].c_ssh);
419 		fdcon[s].c_ssh = NULL;
420 	} else
421 		close(s);
422 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
423 	read_wait[s].fd = -1;
424 	read_wait[s].events = 0;
425 	ncon--;
426 }
427 
428 static int
conrecycle(int s)429 conrecycle(int s)
430 {
431 	con *c = &fdcon[s];
432 	int ret;
433 
434 	ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
435 	confree(s);
436 	return (ret);
437 }
438 
439 static void
congreet(int s)440 congreet(int s)
441 {
442 	int n = 0, remote_major = 0, remote_minor = 0;
443 	char buf[256], *cp;
444 	char remote_version[sizeof buf];
445 	size_t bufsiz;
446 	con *c = &fdcon[s];
447 
448 	/* send client banner */
449 	n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
450 	    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2);
451 	if (n < 0 || (size_t)n >= sizeof(buf)) {
452 		error("snprintf: buffer too small");
453 		confree(s);
454 		return;
455 	}
456 	if (atomicio(vwrite, s, buf, n) != (size_t)n) {
457 		error("write (%s): %s", c->c_name, strerror(errno));
458 		confree(s);
459 		return;
460 	}
461 
462 	/*
463 	 * Read the server banner as per RFC4253 section 4.2.  The "SSH-"
464 	 * protocol identification string may be preceded by an arbitrarily
465 	 * large banner which we must read and ignore.  Loop while reading
466 	 * newline-terminated lines until we have one starting with "SSH-".
467 	 * The ID string cannot be longer than 255 characters although the
468 	 * preceding banner lines may (in which case they'll be discarded
469 	 * in multiple iterations of the outer loop).
470 	 */
471 	for (;;) {
472 		memset(buf, '\0', sizeof(buf));
473 		bufsiz = sizeof(buf);
474 		cp = buf;
475 		while (bufsiz-- &&
476 		    (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') {
477 			if (*cp == '\r')
478 				*cp = '\n';
479 			cp++;
480 		}
481 		if (n != 1 || strncmp(buf, "SSH-", 4) == 0)
482 			break;
483 	}
484 	if (n == 0) {
485 		switch (errno) {
486 		case EPIPE:
487 			error("%s: Connection closed by remote host", c->c_name);
488 			break;
489 		case ECONNREFUSED:
490 			break;
491 		default:
492 			error("read (%s): %s", c->c_name, strerror(errno));
493 			break;
494 		}
495 		conrecycle(s);
496 		return;
497 	}
498 	if (cp >= buf + sizeof(buf)) {
499 		error("%s: greeting exceeds allowable length", c->c_name);
500 		confree(s);
501 		return;
502 	}
503 	if (*cp != '\n' && *cp != '\r') {
504 		error("%s: bad greeting", c->c_name);
505 		confree(s);
506 		return;
507 	}
508 	*cp = '\0';
509 	if ((c->c_ssh = ssh_packet_set_connection(NULL, s, s)) == NULL)
510 		fatal("ssh_packet_set_connection failed");
511 	ssh_packet_set_timeout(c->c_ssh, timeout, 1);
512 	ssh_set_app_data(c->c_ssh, c);	/* back link */
513 	c->c_ssh->compat = 0;
514 	if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
515 	    &remote_major, &remote_minor, remote_version) == 3)
516 		compat_banner(c->c_ssh, remote_version);
517 	if (!ssh2_capable(remote_major, remote_minor)) {
518 		debug("%s doesn't support ssh2", c->c_name);
519 		confree(s);
520 		return;
521 	}
522 	if (!quiet) {
523 		fprintf(stdout, "%c %s:%d %s\n", print_sshfp ? ';' : '#',
524 		    c->c_name, ssh_port, chop(buf));
525 	}
526 	keygrab_ssh2(c);
527 	confree(s);
528 }
529 
530 static void
conread(int s)531 conread(int s)
532 {
533 	con *c = &fdcon[s];
534 
535 	if (c->c_status != CS_CON)
536 		fatal("conread: invalid status %d", c->c_status);
537 
538 	congreet(s);
539 }
540 
541 static void
conloop(void)542 conloop(void)
543 {
544 	struct timespec seltime, now;
545 	con *c;
546 	int i;
547 
548 	monotime_ts(&now);
549 	c = TAILQ_FIRST(&tq);
550 
551 	if (c && timespeccmp(&c->c_ts, &now, >))
552 		timespecsub(&c->c_ts, &now, &seltime);
553 	else
554 		timespecclear(&seltime);
555 
556 	while (ppoll(read_wait, maxfd, &seltime, NULL) == -1) {
557 		if (errno == EAGAIN || errno == EINTR)
558 			continue;
559 		error("poll error");
560 	}
561 
562 	for (i = 0; i < maxfd; i++) {
563 		if (read_wait[i].revents & (POLLHUP|POLLERR|POLLNVAL))
564 			confree(i);
565 		else if (read_wait[i].revents & (POLLIN))
566 			conread(i);
567 	}
568 
569 	c = TAILQ_FIRST(&tq);
570 	while (c && timespeccmp(&c->c_ts, &now, <)) {
571 		int s = c->c_fd;
572 
573 		c = TAILQ_NEXT(c, c_link);
574 		conrecycle(s);
575 	}
576 }
577 
578 static void
do_one_host(char * host)579 do_one_host(char *host)
580 {
581 	char *name = strnnsep(&host, " \t\n");
582 	int j;
583 
584 	if (name == NULL)
585 		return;
586 	for (j = KT_MIN; j <= KT_MAX; j *= 2) {
587 		if (get_keytypes & j) {
588 			while (ncon >= MAXCON)
589 				conloop();
590 			conalloc(name, *host ? host : name, j);
591 		}
592 	}
593 }
594 
595 static void
do_host(char * host)596 do_host(char *host)
597 {
598 	char daddr[128];
599 	struct xaddr addr, end_addr;
600 	u_int masklen;
601 
602 	if (host == NULL)
603 		return;
604 	if (addr_pton_cidr(host, &addr, &masklen) != 0) {
605 		/* Assume argument is a hostname */
606 		do_one_host(host);
607 	} else {
608 		/* Argument is a CIDR range */
609 		debug("CIDR range %s", host);
610 		end_addr = addr;
611 		if (addr_host_to_all1s(&end_addr, masklen) != 0)
612 			goto badaddr;
613 		/*
614 		 * Note: we deliberately include the all-zero/ones addresses.
615 		 */
616 		for (;;) {
617 			if (addr_ntop(&addr, daddr, sizeof(daddr)) != 0) {
618  badaddr:
619 				error("Invalid address %s", host);
620 				return;
621 			}
622 			debug("CIDR expand: address %s", daddr);
623 			do_one_host(daddr);
624 			if (addr_cmp(&addr, &end_addr) == 0)
625 				break;
626 			addr_increment(&addr);
627 		}
628 	}
629 }
630 
631 static void
usage(void)632 usage(void)
633 {
634 	fprintf(stderr,
635 	    "usage: ssh-keyscan [-46cDHqv] [-f file] [-O option] [-p port] [-T timeout]\n"
636 	    "                   [-t type] [host | addrlist namelist]\n");
637 	exit(1);
638 }
639 
640 int
main(int argc,char ** argv)641 main(int argc, char **argv)
642 {
643 	int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
644 	int opt, fopt_count = 0, j;
645 	char *tname, *cp, *line = NULL;
646 	size_t linesize = 0;
647 	FILE *fp;
648 
649 	extern int optind;
650 	extern char *optarg;
651 
652 	TAILQ_INIT(&tq);
653 
654 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
655 	sanitise_stdfd();
656 
657 	if (argc <= 1)
658 		usage();
659 
660 	while ((opt = getopt(argc, argv, "cDHqv46O:p:T:t:f:")) != -1) {
661 		switch (opt) {
662 		case 'H':
663 			hash_hosts = 1;
664 			break;
665 		case 'c':
666 			get_cert = 1;
667 			break;
668 		case 'D':
669 			print_sshfp = 1;
670 			break;
671 		case 'p':
672 			ssh_port = a2port(optarg);
673 			if (ssh_port <= 0) {
674 				fprintf(stderr, "Bad port '%s'\n", optarg);
675 				exit(1);
676 			}
677 			break;
678 		case 'T':
679 			timeout = convtime(optarg);
680 			if (timeout == -1 || timeout == 0) {
681 				fprintf(stderr, "Bad timeout '%s'\n", optarg);
682 				usage();
683 			}
684 			break;
685 		case 'v':
686 			if (!debug_flag) {
687 				debug_flag = 1;
688 				log_level = SYSLOG_LEVEL_DEBUG1;
689 			}
690 			else if (log_level < SYSLOG_LEVEL_DEBUG3)
691 				log_level++;
692 			else
693 				fatal("Too high debugging level.");
694 			break;
695 		case 'q':
696 			quiet = 1;
697 			break;
698 		case 'f':
699 			if (strcmp(optarg, "-") == 0)
700 				optarg = NULL;
701 			argv[fopt_count++] = optarg;
702 			break;
703 		case 'O':
704 			/* Maybe other misc options in the future too */
705 			if (strncmp(optarg, "hashalg=", 8) != 0)
706 				fatal("Unsupported -O option");
707 			if ((hashalg = ssh_digest_alg_by_name(
708 			    optarg + 8)) == -1)
709 				fatal("Unsupported hash algorithm");
710 			break;
711 		case 't':
712 			get_keytypes = 0;
713 			tname = strtok(optarg, ",");
714 			while (tname) {
715 				int type = sshkey_type_from_shortname(tname);
716 
717 				switch (type) {
718 #ifdef WITH_DSA
719 				case KEY_DSA:
720 					get_keytypes |= KT_DSA;
721 					break;
722 #endif
723 				case KEY_ECDSA:
724 					get_keytypes |= KT_ECDSA;
725 					break;
726 				case KEY_RSA:
727 					get_keytypes |= KT_RSA;
728 					break;
729 				case KEY_ED25519:
730 					get_keytypes |= KT_ED25519;
731 					break;
732 				case KEY_XMSS:
733 					get_keytypes |= KT_XMSS;
734 					break;
735 				case KEY_ED25519_SK:
736 					get_keytypes |= KT_ED25519_SK;
737 					break;
738 				case KEY_ECDSA_SK:
739 					get_keytypes |= KT_ECDSA_SK;
740 					break;
741 				case KEY_UNSPEC:
742 				default:
743 					fatal("Unknown key type \"%s\"", tname);
744 				}
745 				tname = strtok(NULL, ",");
746 			}
747 			break;
748 		case '4':
749 			IPv4or6 = AF_INET;
750 			break;
751 		case '6':
752 			IPv4or6 = AF_INET6;
753 			break;
754 		default:
755 			usage();
756 		}
757 	}
758 	if (optind == argc && !fopt_count)
759 		usage();
760 
761 	log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1);
762 
763 	maxfd = fdlim_get(1);
764 	if (maxfd < 0)
765 		fatal("%s: fdlim_get: bad value", __progname);
766 	if (maxfd > MAXMAXFD)
767 		maxfd = MAXMAXFD;
768 	if (MAXCON <= 0)
769 		fatal("%s: not enough file descriptors", __progname);
770 	if (maxfd > fdlim_get(0))
771 		fdlim_set(maxfd);
772 	fdcon = xcalloc(maxfd, sizeof(con));
773 	read_wait = xcalloc(maxfd, sizeof(struct pollfd));
774 	for (j = 0; j < maxfd; j++)
775 		read_wait[j].fd = -1;
776 
777 	for (j = 0; j < fopt_count; j++) {
778 		if (argv[j] == NULL)
779 			fp = stdin;
780 		else if ((fp = fopen(argv[j], "r")) == NULL)
781 			fatal("%s: %s: %s", __progname,
782 			    fp == stdin ? "<stdin>" : argv[j], strerror(errno));
783 
784 		while (getline(&line, &linesize, fp) != -1) {
785 			/* Chomp off trailing whitespace and comments */
786 			if ((cp = strchr(line, '#')) == NULL)
787 				cp = line + strlen(line) - 1;
788 			while (cp >= line) {
789 				if (*cp == ' ' || *cp == '\t' ||
790 				    *cp == '\n' || *cp == '#')
791 					*cp-- = '\0';
792 				else
793 					break;
794 			}
795 
796 			/* Skip empty lines */
797 			if (*line == '\0')
798 				continue;
799 
800 			do_host(line);
801 		}
802 
803 		if (ferror(fp))
804 			fatal("%s: %s: %s", __progname,
805 			    fp == stdin ? "<stdin>" : argv[j], strerror(errno));
806 
807 		if (fp != stdin)
808 			fclose(fp);
809 	}
810 	free(line);
811 
812 	while (optind < argc)
813 		do_host(argv[optind++]);
814 
815 	while (ncon > 0)
816 		conloop();
817 
818 	return found_one ? 0 : 1;
819 }
820