xref: /openbsd-src/usr.bin/ssh/ssh-keyscan.c (revision 256a93a44f36679bee503f12e49566c2183f6181) 
1 /* $OpenBSD: ssh-keyscan.c,v 1.151 2023/02/10 06:41:53 jmc 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 "digest.h"
36 #include "kex.h"
37 #include "compat.h"
38 #include "myproposal.h"
39 #include "packet.h"
40 #include "dispatch.h"
41 #include "log.h"
42 #include "atomicio.h"
43 #include "misc.h"
44 #include "hostfile.h"
45 #include "ssherr.h"
46 #include "ssh_api.h"
47 #include "dns.h"
48 #include "addr.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 #define KT_XMSS		(1<<4)
61 #define KT_ECDSA_SK	(1<<5)
62 #define KT_ED25519_SK	(1<<6)
63 
64 #define KT_MIN		KT_DSA
65 #define KT_MAX		KT_ED25519_SK
66 
67 int get_cert = 0;
68 int get_keytypes = KT_RSA|KT_ECDSA|KT_ED25519|KT_ECDSA_SK|KT_ED25519_SK;
69 
70 int hash_hosts = 0;		/* Hash hostname on output */
71 
72 int print_sshfp = 0;		/* Print SSHFP records instead of known_hosts */
73 
74 int found_one = 0;		/* Successfully found a key */
75 
76 int hashalg = -1;		/* Hash for SSHFP records or -1 for all */
77 
78 #define MAXMAXFD 256
79 
80 /* The number of seconds after which to give up on a TCP connection */
81 int timeout = 5;
82 
83 int maxfd;
84 #define MAXCON (maxfd - 10)
85 
86 extern char *__progname;
87 struct pollfd *read_wait;
88 int ncon;
89 
90 /*
91  * Keep a connection structure for each file descriptor.  The state
92  * associated with file descriptor n is held in fdcon[n].
93  */
94 typedef struct Connection {
95 	u_char c_status;	/* State of connection on this file desc. */
96 #define CS_UNUSED 0		/* File descriptor unused */
97 #define CS_CON 1		/* Waiting to connect/read greeting */
98 #define CS_SIZE 2		/* Waiting to read initial packet size */
99 #define CS_KEYS 3		/* Waiting to read public key packet */
100 	int c_fd;		/* Quick lookup: c->c_fd == c - fdcon */
101 	int c_plen;		/* Packet length field for ssh packet */
102 	int c_len;		/* Total bytes which must be read. */
103 	int c_off;		/* Length of data read so far. */
104 	int c_keytype;		/* Only one of KT_* */
105 	sig_atomic_t c_done;	/* SSH2 done */
106 	char *c_namebase;	/* Address to free for c_name and c_namelist */
107 	char *c_name;		/* Hostname of connection for errors */
108 	char *c_namelist;	/* Pointer to other possible addresses */
109 	char *c_output_name;	/* Hostname of connection for output */
110 	char *c_data;		/* Data read from this fd */
111 	struct ssh *c_ssh;	/* SSH-connection */
112 	struct timespec c_ts;	/* Time at which connection gets aborted */
113 	TAILQ_ENTRY(Connection) c_link;	/* List of connections in timeout order. */
114 } con;
115 
116 TAILQ_HEAD(conlist, Connection) tq;	/* Timeout Queue */
117 con *fdcon;
118 
119 static void keyprint(con *c, struct sshkey *key);
120 
121 static int
122 fdlim_get(int hard)
123 {
124 	struct rlimit rlfd;
125 
126 	if (getrlimit(RLIMIT_NOFILE, &rlfd) == -1)
127 		return (-1);
128 	if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY)
129 		return sysconf(_SC_OPEN_MAX);
130 	else
131 		return hard ? rlfd.rlim_max : rlfd.rlim_cur;
132 }
133 
134 static int
135 fdlim_set(int lim)
136 {
137 	struct rlimit rlfd;
138 
139 	if (lim <= 0)
140 		return (-1);
141 	if (getrlimit(RLIMIT_NOFILE, &rlfd) == -1)
142 		return (-1);
143 	rlfd.rlim_cur = lim;
144 	if (setrlimit(RLIMIT_NOFILE, &rlfd) == -1)
145 		return (-1);
146 	return (0);
147 }
148 
149 /*
150  * This is an strsep function that returns a null field for adjacent
151  * separators.  This is the same as the 4.4BSD strsep, but different from the
152  * one in the GNU libc.
153  */
154 static char *
155 xstrsep(char **str, const char *delim)
156 {
157 	char *s, *e;
158 
159 	if (!**str)
160 		return (NULL);
161 
162 	s = *str;
163 	e = s + strcspn(s, delim);
164 
165 	if (*e != '\0')
166 		*e++ = '\0';
167 	*str = e;
168 
169 	return (s);
170 }
171 
172 /*
173  * Get the next non-null token (like GNU strsep).  Strsep() will return a
174  * null token for two adjacent separators, so we may have to loop.
175  */
176 static char *
177 strnnsep(char **stringp, char *delim)
178 {
179 	char *tok;
180 
181 	do {
182 		tok = xstrsep(stringp, delim);
183 	} while (tok && *tok == '\0');
184 	return (tok);
185 }
186 
187 
188 static int
189 key_print_wrapper(struct sshkey *hostkey, struct ssh *ssh)
190 {
191 	con *c;
192 
193 	if ((c = ssh_get_app_data(ssh)) != NULL)
194 		keyprint(c, hostkey);
195 	/* always abort key exchange */
196 	return -1;
197 }
198 
199 static int
200 ssh2_capable(int remote_major, int remote_minor)
201 {
202 	switch (remote_major) {
203 	case 1:
204 		if (remote_minor == 99)
205 			return 1;
206 		break;
207 	case 2:
208 		return 1;
209 	default:
210 		break;
211 	}
212 	return 0;
213 }
214 
215 static void
216 keygrab_ssh2(con *c)
217 {
218 	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
219 	int r;
220 
221 	switch (c->c_keytype) {
222 	case KT_DSA:
223 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
224 		    "ssh-dss-cert-v01@openssh.com" : "ssh-dss";
225 		break;
226 	case KT_RSA:
227 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
228 		    "rsa-sha2-512-cert-v01@openssh.com,"
229 		    "rsa-sha2-256-cert-v01@openssh.com,"
230 		    "ssh-rsa-cert-v01@openssh.com" :
231 		    "rsa-sha2-512,"
232 		    "rsa-sha2-256,"
233 		    "ssh-rsa";
234 		break;
235 	case KT_ED25519:
236 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
237 		    "ssh-ed25519-cert-v01@openssh.com" : "ssh-ed25519";
238 		break;
239 	case KT_XMSS:
240 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
241 		    "ssh-xmss-cert-v01@openssh.com" : "ssh-xmss@openssh.com";
242 		break;
243 	case KT_ECDSA:
244 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
245 		    "ecdsa-sha2-nistp256-cert-v01@openssh.com,"
246 		    "ecdsa-sha2-nistp384-cert-v01@openssh.com,"
247 		    "ecdsa-sha2-nistp521-cert-v01@openssh.com" :
248 		    "ecdsa-sha2-nistp256,"
249 		    "ecdsa-sha2-nistp384,"
250 		    "ecdsa-sha2-nistp521";
251 		break;
252 	case KT_ECDSA_SK:
253 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
254 		    "sk-ecdsa-sha2-nistp256-cert-v01@openssh.com" :
255 		    "sk-ecdsa-sha2-nistp256@openssh.com";
256 		break;
257 	case KT_ED25519_SK:
258 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
259 		    "sk-ssh-ed25519-cert-v01@openssh.com" :
260 		    "sk-ssh-ed25519@openssh.com";
261 		break;
262 	default:
263 		fatal("unknown key type %d", c->c_keytype);
264 		break;
265 	}
266 	if ((r = kex_setup(c->c_ssh, myproposal)) != 0) {
267 		free(c->c_ssh);
268 		fprintf(stderr, "kex_setup: %s\n", ssh_err(r));
269 		exit(1);
270 	}
271 #ifdef WITH_OPENSSL
272 	c->c_ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client;
273 	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client;
274 	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client;
275 	c->c_ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client;
276 	c->c_ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client;
277 	c->c_ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
278 	c->c_ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
279 	c->c_ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
280 #endif
281 	c->c_ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
282 	c->c_ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client;
283 	ssh_set_verify_host_key_callback(c->c_ssh, key_print_wrapper);
284 	/*
285 	 * do the key-exchange until an error occurs or until
286 	 * the key_print_wrapper() callback sets c_done.
287 	 */
288 	ssh_dispatch_run(c->c_ssh, DISPATCH_BLOCK, &c->c_done);
289 }
290 
291 static void
292 keyprint_one(const char *host, struct sshkey *key)
293 {
294 	char *hostport = NULL, *hashed = NULL;
295 	const char *known_host;
296 
297 	found_one = 1;
298 
299 	if (print_sshfp) {
300 		export_dns_rr(host, key, stdout, 0, hashalg);
301 		return;
302 	}
303 
304 	hostport = put_host_port(host, ssh_port);
305 	lowercase(hostport);
306 	if (hash_hosts && (hashed = host_hash(hostport, NULL, 0)) == NULL)
307 		fatal("host_hash failed");
308 	known_host = hash_hosts ? hashed : hostport;
309 	if (!get_cert)
310 		fprintf(stdout, "%s ", known_host);
311 	sshkey_write(key, stdout);
312 	fputs("\n", stdout);
313 	free(hashed);
314 	free(hostport);
315 }
316 
317 static void
318 keyprint(con *c, struct sshkey *key)
319 {
320 	char *hosts = c->c_output_name ? c->c_output_name : c->c_name;
321 	char *host, *ohosts;
322 
323 	if (key == NULL)
324 		return;
325 	if (get_cert || (!hash_hosts && ssh_port == SSH_DEFAULT_PORT)) {
326 		keyprint_one(hosts, key);
327 		return;
328 	}
329 	ohosts = hosts = xstrdup(hosts);
330 	while ((host = strsep(&hosts, ",")) != NULL)
331 		keyprint_one(host, key);
332 	free(ohosts);
333 }
334 
335 static int
336 tcpconnect(char *host)
337 {
338 	struct addrinfo hints, *ai, *aitop;
339 	char strport[NI_MAXSERV];
340 	int gaierr, s = -1;
341 
342 	snprintf(strport, sizeof strport, "%d", ssh_port);
343 	memset(&hints, 0, sizeof(hints));
344 	hints.ai_family = IPv4or6;
345 	hints.ai_socktype = SOCK_STREAM;
346 	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
347 		error("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr));
348 		return -1;
349 	}
350 	for (ai = aitop; ai; ai = ai->ai_next) {
351 		s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
352 		if (s == -1) {
353 			error("socket: %s", strerror(errno));
354 			continue;
355 		}
356 		if (set_nonblock(s) == -1)
357 			fatal_f("set_nonblock(%d)", s);
358 		if (connect(s, ai->ai_addr, ai->ai_addrlen) == -1 &&
359 		    errno != EINPROGRESS)
360 			error("connect (`%s'): %s", host, strerror(errno));
361 		else
362 			break;
363 		close(s);
364 		s = -1;
365 	}
366 	freeaddrinfo(aitop);
367 	return s;
368 }
369 
370 static int
371 conalloc(const char *iname, const char *oname, int keytype)
372 {
373 	char *namebase, *name, *namelist;
374 	int s;
375 
376 	namebase = namelist = xstrdup(iname);
377 
378 	do {
379 		name = xstrsep(&namelist, ",");
380 		if (!name) {
381 			free(namebase);
382 			return (-1);
383 		}
384 	} while ((s = tcpconnect(name)) < 0);
385 
386 	if (s >= maxfd)
387 		fatal("conalloc: fdno %d too high", s);
388 	if (fdcon[s].c_status)
389 		fatal("conalloc: attempt to reuse fdno %d", s);
390 
391 	debug3_f("oname %s kt %d", oname, keytype);
392 	fdcon[s].c_fd = s;
393 	fdcon[s].c_status = CS_CON;
394 	fdcon[s].c_namebase = namebase;
395 	fdcon[s].c_name = name;
396 	fdcon[s].c_namelist = namelist;
397 	fdcon[s].c_output_name = xstrdup(oname);
398 	fdcon[s].c_data = (char *) &fdcon[s].c_plen;
399 	fdcon[s].c_len = 4;
400 	fdcon[s].c_off = 0;
401 	fdcon[s].c_keytype = keytype;
402 	monotime_ts(&fdcon[s].c_ts);
403 	fdcon[s].c_ts.tv_sec += timeout;
404 	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
405 	read_wait[s].fd = s;
406 	read_wait[s].events = POLLIN;
407 	ncon++;
408 	return (s);
409 }
410 
411 static void
412 confree(int s)
413 {
414 	if (s >= maxfd || fdcon[s].c_status == CS_UNUSED)
415 		fatal("confree: attempt to free bad fdno %d", s);
416 	free(fdcon[s].c_namebase);
417 	free(fdcon[s].c_output_name);
418 	if (fdcon[s].c_status == CS_KEYS)
419 		free(fdcon[s].c_data);
420 	fdcon[s].c_status = CS_UNUSED;
421 	fdcon[s].c_keytype = 0;
422 	if (fdcon[s].c_ssh) {
423 		ssh_packet_close(fdcon[s].c_ssh);
424 		free(fdcon[s].c_ssh);
425 		fdcon[s].c_ssh = NULL;
426 	} else
427 		close(s);
428 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
429 	read_wait[s].fd = -1;
430 	read_wait[s].events = 0;
431 	ncon--;
432 }
433 
434 static void
435 contouch(int s)
436 {
437 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
438 	monotime_ts(&fdcon[s].c_ts);
439 	fdcon[s].c_ts.tv_sec += timeout;
440 	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
441 }
442 
443 static int
444 conrecycle(int s)
445 {
446 	con *c = &fdcon[s];
447 	int ret;
448 
449 	ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
450 	confree(s);
451 	return (ret);
452 }
453 
454 static void
455 congreet(int s)
456 {
457 	int n = 0, remote_major = 0, remote_minor = 0;
458 	char buf[256], *cp;
459 	char remote_version[sizeof buf];
460 	size_t bufsiz;
461 	con *c = &fdcon[s];
462 
463 	/* send client banner */
464 	n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
465 	    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2);
466 	if (n < 0 || (size_t)n >= sizeof(buf)) {
467 		error("snprintf: buffer too small");
468 		confree(s);
469 		return;
470 	}
471 	if (atomicio(vwrite, s, buf, n) != (size_t)n) {
472 		error("write (%s): %s", c->c_name, strerror(errno));
473 		confree(s);
474 		return;
475 	}
476 
477 	/*
478 	 * Read the server banner as per RFC4253 section 4.2.  The "SSH-"
479 	 * protocol identification string may be preceeded by an arbitrarily
480 	 * large banner which we must read and ignore.  Loop while reading
481 	 * newline-terminated lines until we have one starting with "SSH-".
482 	 * The ID string cannot be longer than 255 characters although the
483 	 * preceeding banner lines may (in which case they'll be discarded
484 	 * in multiple iterations of the outer loop).
485 	 */
486 	for (;;) {
487 		memset(buf, '\0', sizeof(buf));
488 		bufsiz = sizeof(buf);
489 		cp = buf;
490 		while (bufsiz-- &&
491 		    (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') {
492 			if (*cp == '\r')
493 				*cp = '\n';
494 			cp++;
495 		}
496 		if (n != 1 || strncmp(buf, "SSH-", 4) == 0)
497 			break;
498 	}
499 	if (n == 0) {
500 		switch (errno) {
501 		case EPIPE:
502 			error("%s: Connection closed by remote host", c->c_name);
503 			break;
504 		case ECONNREFUSED:
505 			break;
506 		default:
507 			error("read (%s): %s", c->c_name, strerror(errno));
508 			break;
509 		}
510 		conrecycle(s);
511 		return;
512 	}
513 	if (cp >= buf + sizeof(buf)) {
514 		error("%s: greeting exceeds allowable length", c->c_name);
515 		confree(s);
516 		return;
517 	}
518 	if (*cp != '\n' && *cp != '\r') {
519 		error("%s: bad greeting", c->c_name);
520 		confree(s);
521 		return;
522 	}
523 	*cp = '\0';
524 	if ((c->c_ssh = ssh_packet_set_connection(NULL, s, s)) == NULL)
525 		fatal("ssh_packet_set_connection failed");
526 	ssh_packet_set_timeout(c->c_ssh, timeout, 1);
527 	ssh_set_app_data(c->c_ssh, c);	/* back link */
528 	c->c_ssh->compat = 0;
529 	if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
530 	    &remote_major, &remote_minor, remote_version) == 3)
531 		compat_banner(c->c_ssh, remote_version);
532 	if (!ssh2_capable(remote_major, remote_minor)) {
533 		debug("%s doesn't support ssh2", c->c_name);
534 		confree(s);
535 		return;
536 	}
537 	fprintf(stderr, "%c %s:%d %s\n", print_sshfp ? ';' : '#',
538 	    c->c_name, ssh_port, chop(buf));
539 	keygrab_ssh2(c);
540 	confree(s);
541 }
542 
543 static void
544 conread(int s)
545 {
546 	con *c = &fdcon[s];
547 	size_t n;
548 
549 	if (c->c_status == CS_CON) {
550 		congreet(s);
551 		return;
552 	}
553 	n = atomicio(read, s, c->c_data + c->c_off, c->c_len - c->c_off);
554 	if (n == 0) {
555 		error("read (%s): %s", c->c_name, strerror(errno));
556 		confree(s);
557 		return;
558 	}
559 	c->c_off += n;
560 
561 	if (c->c_off == c->c_len)
562 		switch (c->c_status) {
563 		case CS_SIZE:
564 			c->c_plen = htonl(c->c_plen);
565 			c->c_len = c->c_plen + 8 - (c->c_plen & 7);
566 			c->c_off = 0;
567 			c->c_data = xmalloc(c->c_len);
568 			c->c_status = CS_KEYS;
569 			break;
570 		default:
571 			fatal("conread: invalid status %d", c->c_status);
572 			break;
573 		}
574 
575 	contouch(s);
576 }
577 
578 static void
579 conloop(void)
580 {
581 	struct timespec seltime, now;
582 	con *c;
583 	int i;
584 
585 	monotime_ts(&now);
586 	c = TAILQ_FIRST(&tq);
587 
588 	if (c && timespeccmp(&c->c_ts, &now, >))
589 		timespecsub(&c->c_ts, &now, &seltime);
590 	else
591 		timespecclear(&seltime);
592 
593 	while (ppoll(read_wait, maxfd, &seltime, NULL) == -1) {
594 		if (errno == EAGAIN || errno == EINTR)
595 			continue;
596 		error("poll error");
597 	}
598 
599 	for (i = 0; i < maxfd; i++) {
600 		if (read_wait[i].revents & (POLLHUP|POLLERR|POLLNVAL))
601 			confree(i);
602 		else if (read_wait[i].revents & (POLLIN|POLLHUP))
603 			conread(i);
604 	}
605 
606 	c = TAILQ_FIRST(&tq);
607 	while (c && timespeccmp(&c->c_ts, &now, <)) {
608 		int s = c->c_fd;
609 
610 		c = TAILQ_NEXT(c, c_link);
611 		conrecycle(s);
612 	}
613 }
614 
615 static void
616 do_one_host(char *host)
617 {
618 	char *name = strnnsep(&host, " \t\n");
619 	int j;
620 
621 	if (name == NULL)
622 		return;
623 	for (j = KT_MIN; j <= KT_MAX; j *= 2) {
624 		if (get_keytypes & j) {
625 			while (ncon >= MAXCON)
626 				conloop();
627 			conalloc(name, *host ? host : name, j);
628 		}
629 	}
630 }
631 
632 static void
633 do_host(char *host)
634 {
635 	char daddr[128];
636 	struct xaddr addr, end_addr;
637 	u_int masklen;
638 
639 	if (host == NULL)
640 		return;
641 	if (addr_pton_cidr(host, &addr, &masklen) != 0) {
642 		/* Assume argument is a hostname */
643 		do_one_host(host);
644 	} else {
645 		/* Argument is a CIDR range */
646 		debug("CIDR range %s", host);
647 		end_addr = addr;
648 		if (addr_host_to_all1s(&end_addr, masklen) != 0)
649 			goto badaddr;
650 		/*
651 		 * Note: we deliberately include the all-zero/ones addresses.
652 		 */
653 		for (;;) {
654 			if (addr_ntop(&addr, daddr, sizeof(daddr)) != 0) {
655  badaddr:
656 				error("Invalid address %s", host);
657 				return;
658 			}
659 			debug("CIDR expand: address %s", daddr);
660 			do_one_host(daddr);
661 			if (addr_cmp(&addr, &end_addr) == 0)
662 				break;
663 			addr_increment(&addr);
664 		};
665 	}
666 }
667 
668 void
669 sshfatal(const char *file, const char *func, int line, int showfunc,
670     LogLevel level, const char *suffix, const char *fmt, ...)
671 {
672 	va_list args;
673 
674 	va_start(args, fmt);
675 	sshlogv(file, func, line, showfunc, level, suffix, fmt, args);
676 	va_end(args);
677 	cleanup_exit(255);
678 }
679 
680 static void
681 usage(void)
682 {
683 	fprintf(stderr,
684 	    "usage: ssh-keyscan [-46cDHv] [-f file] [-O option] [-p port] [-T timeout]\n"
685 	    "                   [-t type] [host | addrlist namelist]\n");
686 	exit(1);
687 }
688 
689 int
690 main(int argc, char **argv)
691 {
692 	int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
693 	int opt, fopt_count = 0, j;
694 	char *tname, *cp, *line = NULL;
695 	size_t linesize = 0;
696 	FILE *fp;
697 
698 	extern int optind;
699 	extern char *optarg;
700 
701 	TAILQ_INIT(&tq);
702 
703 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
704 	sanitise_stdfd();
705 
706 	if (argc <= 1)
707 		usage();
708 
709 	while ((opt = getopt(argc, argv, "cDHv46O:p:T:t:f:")) != -1) {
710 		switch (opt) {
711 		case 'H':
712 			hash_hosts = 1;
713 			break;
714 		case 'c':
715 			get_cert = 1;
716 			break;
717 		case 'D':
718 			print_sshfp = 1;
719 			break;
720 		case 'p':
721 			ssh_port = a2port(optarg);
722 			if (ssh_port <= 0) {
723 				fprintf(stderr, "Bad port '%s'\n", optarg);
724 				exit(1);
725 			}
726 			break;
727 		case 'T':
728 			timeout = convtime(optarg);
729 			if (timeout == -1 || timeout == 0) {
730 				fprintf(stderr, "Bad timeout '%s'\n", optarg);
731 				usage();
732 			}
733 			break;
734 		case 'v':
735 			if (!debug_flag) {
736 				debug_flag = 1;
737 				log_level = SYSLOG_LEVEL_DEBUG1;
738 			}
739 			else if (log_level < SYSLOG_LEVEL_DEBUG3)
740 				log_level++;
741 			else
742 				fatal("Too high debugging level.");
743 			break;
744 		case 'f':
745 			if (strcmp(optarg, "-") == 0)
746 				optarg = NULL;
747 			argv[fopt_count++] = optarg;
748 			break;
749 		case 'O':
750 			/* Maybe other misc options in the future too */
751 			if (strncmp(optarg, "hashalg=", 8) != 0)
752 				fatal("Unsupported -O option");
753 			if ((hashalg = ssh_digest_alg_by_name(
754 			    optarg + 8)) == -1)
755 				fatal("Unsupported hash algorithm");
756 			break;
757 		case 't':
758 			get_keytypes = 0;
759 			tname = strtok(optarg, ",");
760 			while (tname) {
761 				int type = sshkey_type_from_name(tname);
762 
763 				switch (type) {
764 				case KEY_DSA:
765 					get_keytypes |= KT_DSA;
766 					break;
767 				case KEY_ECDSA:
768 					get_keytypes |= KT_ECDSA;
769 					break;
770 				case KEY_RSA:
771 					get_keytypes |= KT_RSA;
772 					break;
773 				case KEY_ED25519:
774 					get_keytypes |= KT_ED25519;
775 					break;
776 				case KEY_XMSS:
777 					get_keytypes |= KT_XMSS;
778 					break;
779 				case KEY_ED25519_SK:
780 					get_keytypes |= KT_ED25519_SK;
781 					break;
782 				case KEY_ECDSA_SK:
783 					get_keytypes |= KT_ECDSA_SK;
784 					break;
785 				case KEY_UNSPEC:
786 				default:
787 					fatal("Unknown key type \"%s\"", tname);
788 				}
789 				tname = strtok(NULL, ",");
790 			}
791 			break;
792 		case '4':
793 			IPv4or6 = AF_INET;
794 			break;
795 		case '6':
796 			IPv4or6 = AF_INET6;
797 			break;
798 		default:
799 			usage();
800 		}
801 	}
802 	if (optind == argc && !fopt_count)
803 		usage();
804 
805 	log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1);
806 
807 	maxfd = fdlim_get(1);
808 	if (maxfd < 0)
809 		fatal("%s: fdlim_get: bad value", __progname);
810 	if (maxfd > MAXMAXFD)
811 		maxfd = MAXMAXFD;
812 	if (MAXCON <= 0)
813 		fatal("%s: not enough file descriptors", __progname);
814 	if (maxfd > fdlim_get(0))
815 		fdlim_set(maxfd);
816 	fdcon = xcalloc(maxfd, sizeof(con));
817 	read_wait = xcalloc(maxfd, sizeof(struct pollfd));
818 	for (j = 0; j < maxfd; j++)
819 		read_wait[j].fd = -1;
820 
821 	for (j = 0; j < fopt_count; j++) {
822 		if (argv[j] == NULL)
823 			fp = stdin;
824 		else if ((fp = fopen(argv[j], "r")) == NULL)
825 			fatal("%s: %s: %s", __progname, argv[j], strerror(errno));
826 
827 		while (getline(&line, &linesize, fp) != -1) {
828 			/* Chomp off trailing whitespace and comments */
829 			if ((cp = strchr(line, '#')) == NULL)
830 				cp = line + strlen(line) - 1;
831 			while (cp >= line) {
832 				if (*cp == ' ' || *cp == '\t' ||
833 				    *cp == '\n' || *cp == '#')
834 					*cp-- = '\0';
835 				else
836 					break;
837 			}
838 
839 			/* Skip empty lines */
840 			if (*line == '\0')
841 				continue;
842 
843 			do_host(line);
844 		}
845 
846 		if (ferror(fp))
847 			fatal("%s: %s: %s", __progname, argv[j], strerror(errno));
848 
849 		fclose(fp);
850 	}
851 	free(line);
852 
853 	while (optind < argc)
854 		do_host(argv[optind++]);
855 
856 	while (ncon > 0)
857 		conloop();
858 
859 	return found_one ? 0 : 1;
860 }
861