xref: /freebsd/crypto/openssh/ssh-keyscan.c (revision 3fb2e045791eb6f003205902cdc4f74702770ec6) 
1 /* $OpenBSD: ssh-keyscan.c,v 1.155 2024/01/11 01:45:36 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 "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 #ifdef WITH_OPENSSL
23 #include <openssl/bn.h>
24 #endif
25 
26 #include <limits.h>
27 #include <netdb.h>
28 #include <errno.h>
29 #ifdef HAVE_POLL_H
30 #include <poll.h>
31 #endif
32 #include <stdarg.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <signal.h>
36 #include <string.h>
37 #include <unistd.h>
38 
39 #include "xmalloc.h"
40 #include "ssh.h"
41 #include "sshbuf.h"
42 #include "sshkey.h"
43 #include "cipher.h"
44 #include "digest.h"
45 #include "kex.h"
46 #include "compat.h"
47 #include "myproposal.h"
48 #include "packet.h"
49 #include "dispatch.h"
50 #include "log.h"
51 #include "atomicio.h"
52 #include "misc.h"
53 #include "hostfile.h"
54 #include "ssherr.h"
55 #include "ssh_api.h"
56 #include "dns.h"
57 #include "addr.h"
58 
59 /* Flag indicating whether IPv4 or IPv6.  This can be set on the command line.
60    Default value is AF_UNSPEC means both IPv4 and IPv6. */
61 int IPv4or6 = AF_UNSPEC;
62 
63 int ssh_port = SSH_DEFAULT_PORT;
64 
65 #define KT_DSA		(1)
66 #define KT_RSA		(1<<1)
67 #define KT_ECDSA	(1<<2)
68 #define KT_ED25519	(1<<3)
69 #define KT_XMSS		(1<<4)
70 #define KT_ECDSA_SK	(1<<5)
71 #define KT_ED25519_SK	(1<<6)
72 
73 #define KT_MIN		KT_DSA
74 #define KT_MAX		KT_ED25519_SK
75 
76 int get_cert = 0;
77 int get_keytypes = KT_RSA|KT_ECDSA|KT_ED25519|KT_ECDSA_SK|KT_ED25519_SK;
78 
79 int hash_hosts = 0;		/* Hash hostname on output */
80 
81 int print_sshfp = 0;		/* Print SSHFP records instead of known_hosts */
82 
83 int found_one = 0;		/* Successfully found a key */
84 
85 int hashalg = -1;		/* Hash for SSHFP records or -1 for all */
86 
87 #define MAXMAXFD 256
88 
89 /* The number of seconds after which to give up on a TCP connection */
90 int timeout = 5;
91 
92 int maxfd;
93 #define MAXCON (maxfd - 10)
94 
95 extern char *__progname;
96 struct pollfd *read_wait;
97 int ncon;
98 
99 /*
100  * Keep a connection structure for each file descriptor.  The state
101  * associated with file descriptor n is held in fdcon[n].
102  */
103 typedef struct Connection {
104 	u_char c_status;	/* State of connection on this file desc. */
105 #define CS_UNUSED 0		/* File descriptor unused */
106 #define CS_CON 1		/* Waiting to connect/read greeting */
107 #define CS_SIZE 2		/* Waiting to read initial packet size */
108 #define CS_KEYS 3		/* Waiting to read public key packet */
109 	int c_fd;		/* Quick lookup: c->c_fd == c - fdcon */
110 	int c_plen;		/* Packet length field for ssh packet */
111 	int c_len;		/* Total bytes which must be read. */
112 	int c_off;		/* Length of data read so far. */
113 	int c_keytype;		/* Only one of KT_* */
114 	sig_atomic_t c_done;	/* SSH2 done */
115 	char *c_namebase;	/* Address to free for c_name and c_namelist */
116 	char *c_name;		/* Hostname of connection for errors */
117 	char *c_namelist;	/* Pointer to other possible addresses */
118 	char *c_output_name;	/* Hostname of connection for output */
119 	char *c_data;		/* Data read from this fd */
120 	struct ssh *c_ssh;	/* SSH-connection */
121 	struct timespec c_ts;	/* Time at which connection gets aborted */
122 	TAILQ_ENTRY(Connection) c_link;	/* List of connections in timeout order. */
123 } con;
124 
125 TAILQ_HEAD(conlist, Connection) tq;	/* Timeout Queue */
126 con *fdcon;
127 
128 static void keyprint(con *c, struct sshkey *key);
129 
130 static int
131 fdlim_get(int hard)
132 {
133 #if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
134 	struct rlimit rlfd;
135 	rlim_t lim;
136 
137 	if (getrlimit(RLIMIT_NOFILE, &rlfd) == -1)
138 		return -1;
139 	lim = hard ? rlfd.rlim_max : rlfd.rlim_cur;
140 	if (lim <= 0)
141 		return -1;
142 	if (lim == RLIM_INFINITY)
143 		lim = SSH_SYSFDMAX;
144 	if (lim >= INT_MAX)
145 		lim = INT_MAX;
146 	return lim;
147 #else
148 	return (SSH_SYSFDMAX <= 0) ? -1 :
149 	    ((SSH_SYSFDMAX >= INT_MAX) ? INT_MAX : SSH_SYSFDMAX);
150 #endif
151 }
152 
153 static int
154 fdlim_set(int lim)
155 {
156 #if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
157 	struct rlimit rlfd;
158 #endif
159 
160 	if (lim <= 0)
161 		return (-1);
162 #if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
163 	if (getrlimit(RLIMIT_NOFILE, &rlfd) == -1)
164 		return (-1);
165 	rlfd.rlim_cur = lim;
166 	if (setrlimit(RLIMIT_NOFILE, &rlfd) == -1)
167 		return (-1);
168 #elif defined (HAVE_SETDTABLESIZE)
169 	setdtablesize(lim);
170 #endif
171 	return (0);
172 }
173 
174 /*
175  * This is an strsep function that returns a null field for adjacent
176  * separators.  This is the same as the 4.4BSD strsep, but different from the
177  * one in the GNU libc.
178  */
179 static char *
180 xstrsep(char **str, const char *delim)
181 {
182 	char *s, *e;
183 
184 	if (!**str)
185 		return (NULL);
186 
187 	s = *str;
188 	e = s + strcspn(s, delim);
189 
190 	if (*e != '\0')
191 		*e++ = '\0';
192 	*str = e;
193 
194 	return (s);
195 }
196 
197 /*
198  * Get the next non-null token (like GNU strsep).  Strsep() will return a
199  * null token for two adjacent separators, so we may have to loop.
200  */
201 static char *
202 strnnsep(char **stringp, char *delim)
203 {
204 	char *tok;
205 
206 	do {
207 		tok = xstrsep(stringp, delim);
208 	} while (tok && *tok == '\0');
209 	return (tok);
210 }
211 
212 
213 static int
214 key_print_wrapper(struct sshkey *hostkey, struct ssh *ssh)
215 {
216 	con *c;
217 
218 	if ((c = ssh_get_app_data(ssh)) != NULL)
219 		keyprint(c, hostkey);
220 	/* always abort key exchange */
221 	return -1;
222 }
223 
224 static int
225 ssh2_capable(int remote_major, int remote_minor)
226 {
227 	switch (remote_major) {
228 	case 1:
229 		if (remote_minor == 99)
230 			return 1;
231 		break;
232 	case 2:
233 		return 1;
234 	default:
235 		break;
236 	}
237 	return 0;
238 }
239 
240 static void
241 keygrab_ssh2(con *c)
242 {
243 	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
244 	int r;
245 
246 	switch (c->c_keytype) {
247 	case KT_DSA:
248 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
249 		    "ssh-dss-cert-v01@openssh.com" : "ssh-dss";
250 		break;
251 	case KT_RSA:
252 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
253 		    "rsa-sha2-512-cert-v01@openssh.com,"
254 		    "rsa-sha2-256-cert-v01@openssh.com,"
255 		    "ssh-rsa-cert-v01@openssh.com" :
256 		    "rsa-sha2-512,"
257 		    "rsa-sha2-256,"
258 		    "ssh-rsa";
259 		break;
260 	case KT_ED25519:
261 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
262 		    "ssh-ed25519-cert-v01@openssh.com" : "ssh-ed25519";
263 		break;
264 	case KT_XMSS:
265 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
266 		    "ssh-xmss-cert-v01@openssh.com" : "ssh-xmss@openssh.com";
267 		break;
268 	case KT_ECDSA:
269 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
270 		    "ecdsa-sha2-nistp256-cert-v01@openssh.com,"
271 		    "ecdsa-sha2-nistp384-cert-v01@openssh.com,"
272 		    "ecdsa-sha2-nistp521-cert-v01@openssh.com" :
273 		    "ecdsa-sha2-nistp256,"
274 		    "ecdsa-sha2-nistp384,"
275 		    "ecdsa-sha2-nistp521";
276 		break;
277 	case KT_ECDSA_SK:
278 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
279 		    "sk-ecdsa-sha2-nistp256-cert-v01@openssh.com" :
280 		    "sk-ecdsa-sha2-nistp256@openssh.com";
281 		break;
282 	case KT_ED25519_SK:
283 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
284 		    "sk-ssh-ed25519-cert-v01@openssh.com" :
285 		    "sk-ssh-ed25519@openssh.com";
286 		break;
287 	default:
288 		fatal("unknown key type %d", c->c_keytype);
289 		break;
290 	}
291 	if ((r = kex_setup(c->c_ssh, myproposal)) != 0) {
292 		free(c->c_ssh);
293 		fprintf(stderr, "kex_setup: %s\n", ssh_err(r));
294 		exit(1);
295 	}
296 #ifdef WITH_OPENSSL
297 	c->c_ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client;
298 	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client;
299 	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client;
300 	c->c_ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client;
301 	c->c_ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client;
302 	c->c_ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
303 	c->c_ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
304 # ifdef OPENSSL_HAS_ECC
305 	c->c_ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
306 # endif
307 #endif
308 	c->c_ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
309 	c->c_ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client;
310 	ssh_set_verify_host_key_callback(c->c_ssh, key_print_wrapper);
311 	/*
312 	 * do the key-exchange until an error occurs or until
313 	 * the key_print_wrapper() callback sets c_done.
314 	 */
315 	ssh_dispatch_run(c->c_ssh, DISPATCH_BLOCK, &c->c_done);
316 }
317 
318 static void
319 keyprint_one(const char *host, struct sshkey *key)
320 {
321 	char *hostport = NULL, *hashed = NULL;
322 	const char *known_host;
323 	int r = 0;
324 
325 	found_one = 1;
326 
327 	if (print_sshfp) {
328 		export_dns_rr(host, key, stdout, 0, hashalg);
329 		return;
330 	}
331 
332 	hostport = put_host_port(host, ssh_port);
333 	lowercase(hostport);
334 	if (hash_hosts && (hashed = host_hash(hostport, NULL, 0)) == NULL)
335 		fatal("host_hash failed");
336 	known_host = hash_hosts ? hashed : hostport;
337 	if (!get_cert)
338 		r = fprintf(stdout, "%s ", known_host);
339 	if (r >= 0 && sshkey_write(key, stdout) == 0)
340 		(void)fputs("\n", stdout);
341 	free(hashed);
342 	free(hostport);
343 }
344 
345 static void
346 keyprint(con *c, struct sshkey *key)
347 {
348 	char *hosts = c->c_output_name ? c->c_output_name : c->c_name;
349 	char *host, *ohosts;
350 
351 	if (key == NULL)
352 		return;
353 	if (get_cert || (!hash_hosts && ssh_port == SSH_DEFAULT_PORT)) {
354 		keyprint_one(hosts, key);
355 		return;
356 	}
357 	ohosts = hosts = xstrdup(hosts);
358 	while ((host = strsep(&hosts, ",")) != NULL)
359 		keyprint_one(host, key);
360 	free(ohosts);
361 }
362 
363 static int
364 tcpconnect(char *host)
365 {
366 	struct addrinfo hints, *ai, *aitop;
367 	char strport[NI_MAXSERV];
368 	int gaierr, s = -1;
369 
370 	snprintf(strport, sizeof strport, "%d", ssh_port);
371 	memset(&hints, 0, sizeof(hints));
372 	hints.ai_family = IPv4or6;
373 	hints.ai_socktype = SOCK_STREAM;
374 	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
375 		error("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr));
376 		return -1;
377 	}
378 	for (ai = aitop; ai; ai = ai->ai_next) {
379 		s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
380 		if (s == -1) {
381 			error("socket: %s", strerror(errno));
382 			continue;
383 		}
384 		if (set_nonblock(s) == -1)
385 			fatal_f("set_nonblock(%d)", s);
386 		if (connect(s, ai->ai_addr, ai->ai_addrlen) == -1 &&
387 		    errno != EINPROGRESS)
388 			error("connect (`%s'): %s", host, strerror(errno));
389 		else
390 			break;
391 		close(s);
392 		s = -1;
393 	}
394 	freeaddrinfo(aitop);
395 	return s;
396 }
397 
398 static int
399 conalloc(const char *iname, const char *oname, int keytype)
400 {
401 	char *namebase, *name, *namelist;
402 	int s;
403 
404 	namebase = namelist = xstrdup(iname);
405 
406 	do {
407 		name = xstrsep(&namelist, ",");
408 		if (!name) {
409 			free(namebase);
410 			return (-1);
411 		}
412 	} while ((s = tcpconnect(name)) < 0);
413 
414 	if (s >= maxfd)
415 		fatal("conalloc: fdno %d too high", s);
416 	if (fdcon[s].c_status)
417 		fatal("conalloc: attempt to reuse fdno %d", s);
418 
419 	debug3_f("oname %s kt %d", oname, keytype);
420 	fdcon[s].c_fd = s;
421 	fdcon[s].c_status = CS_CON;
422 	fdcon[s].c_namebase = namebase;
423 	fdcon[s].c_name = name;
424 	fdcon[s].c_namelist = namelist;
425 	fdcon[s].c_output_name = xstrdup(oname);
426 	fdcon[s].c_data = (char *) &fdcon[s].c_plen;
427 	fdcon[s].c_len = 4;
428 	fdcon[s].c_off = 0;
429 	fdcon[s].c_keytype = keytype;
430 	monotime_ts(&fdcon[s].c_ts);
431 	fdcon[s].c_ts.tv_sec += timeout;
432 	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
433 	read_wait[s].fd = s;
434 	read_wait[s].events = POLLIN;
435 	ncon++;
436 	return (s);
437 }
438 
439 static void
440 confree(int s)
441 {
442 	if (s >= maxfd || fdcon[s].c_status == CS_UNUSED)
443 		fatal("confree: attempt to free bad fdno %d", s);
444 	free(fdcon[s].c_namebase);
445 	free(fdcon[s].c_output_name);
446 	if (fdcon[s].c_status == CS_KEYS)
447 		free(fdcon[s].c_data);
448 	fdcon[s].c_status = CS_UNUSED;
449 	fdcon[s].c_keytype = 0;
450 	if (fdcon[s].c_ssh) {
451 		ssh_packet_close(fdcon[s].c_ssh);
452 		free(fdcon[s].c_ssh);
453 		fdcon[s].c_ssh = NULL;
454 	} else
455 		close(s);
456 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
457 	read_wait[s].fd = -1;
458 	read_wait[s].events = 0;
459 	ncon--;
460 }
461 
462 static void
463 contouch(int s)
464 {
465 	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
466 	monotime_ts(&fdcon[s].c_ts);
467 	fdcon[s].c_ts.tv_sec += timeout;
468 	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
469 }
470 
471 static int
472 conrecycle(int s)
473 {
474 	con *c = &fdcon[s];
475 	int ret;
476 
477 	ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
478 	confree(s);
479 	return (ret);
480 }
481 
482 static void
483 congreet(int s)
484 {
485 	int n = 0, remote_major = 0, remote_minor = 0;
486 	char buf[256], *cp;
487 	char remote_version[sizeof buf];
488 	size_t bufsiz;
489 	con *c = &fdcon[s];
490 
491 	/* send client banner */
492 	n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
493 	    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2);
494 	if (n < 0 || (size_t)n >= sizeof(buf)) {
495 		error("snprintf: buffer too small");
496 		confree(s);
497 		return;
498 	}
499 	if (atomicio(vwrite, s, buf, n) != (size_t)n) {
500 		error("write (%s): %s", c->c_name, strerror(errno));
501 		confree(s);
502 		return;
503 	}
504 
505 	/*
506 	 * Read the server banner as per RFC4253 section 4.2.  The "SSH-"
507 	 * protocol identification string may be preceded by an arbitrarily
508 	 * large banner which we must read and ignore.  Loop while reading
509 	 * newline-terminated lines until we have one starting with "SSH-".
510 	 * The ID string cannot be longer than 255 characters although the
511 	 * preceding banner lines may (in which case they'll be discarded
512 	 * in multiple iterations of the outer loop).
513 	 */
514 	for (;;) {
515 		memset(buf, '\0', sizeof(buf));
516 		bufsiz = sizeof(buf);
517 		cp = buf;
518 		while (bufsiz-- &&
519 		    (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') {
520 			if (*cp == '\r')
521 				*cp = '\n';
522 			cp++;
523 		}
524 		if (n != 1 || strncmp(buf, "SSH-", 4) == 0)
525 			break;
526 	}
527 	if (n == 0) {
528 		switch (errno) {
529 		case EPIPE:
530 			error("%s: Connection closed by remote host", c->c_name);
531 			break;
532 		case ECONNREFUSED:
533 			break;
534 		default:
535 			error("read (%s): %s", c->c_name, strerror(errno));
536 			break;
537 		}
538 		conrecycle(s);
539 		return;
540 	}
541 	if (cp >= buf + sizeof(buf)) {
542 		error("%s: greeting exceeds allowable length", c->c_name);
543 		confree(s);
544 		return;
545 	}
546 	if (*cp != '\n' && *cp != '\r') {
547 		error("%s: bad greeting", c->c_name);
548 		confree(s);
549 		return;
550 	}
551 	*cp = '\0';
552 	if ((c->c_ssh = ssh_packet_set_connection(NULL, s, s)) == NULL)
553 		fatal("ssh_packet_set_connection failed");
554 	ssh_packet_set_timeout(c->c_ssh, timeout, 1);
555 	ssh_set_app_data(c->c_ssh, c);	/* back link */
556 	c->c_ssh->compat = 0;
557 	if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
558 	    &remote_major, &remote_minor, remote_version) == 3)
559 		compat_banner(c->c_ssh, remote_version);
560 	if (!ssh2_capable(remote_major, remote_minor)) {
561 		debug("%s doesn't support ssh2", c->c_name);
562 		confree(s);
563 		return;
564 	}
565 	fprintf(stderr, "%c %s:%d %s\n", print_sshfp ? ';' : '#',
566 	    c->c_name, ssh_port, chop(buf));
567 	keygrab_ssh2(c);
568 	confree(s);
569 }
570 
571 static void
572 conread(int s)
573 {
574 	con *c = &fdcon[s];
575 	size_t n;
576 
577 	if (c->c_status == CS_CON) {
578 		congreet(s);
579 		return;
580 	}
581 	n = atomicio(read, s, c->c_data + c->c_off, c->c_len - c->c_off);
582 	if (n == 0) {
583 		error("read (%s): %s", c->c_name, strerror(errno));
584 		confree(s);
585 		return;
586 	}
587 	c->c_off += n;
588 
589 	if (c->c_off == c->c_len)
590 		switch (c->c_status) {
591 		case CS_SIZE:
592 			c->c_plen = htonl(c->c_plen);
593 			c->c_len = c->c_plen + 8 - (c->c_plen & 7);
594 			c->c_off = 0;
595 			c->c_data = xmalloc(c->c_len);
596 			c->c_status = CS_KEYS;
597 			break;
598 		default:
599 			fatal("conread: invalid status %d", c->c_status);
600 			break;
601 		}
602 
603 	contouch(s);
604 }
605 
606 static void
607 conloop(void)
608 {
609 	struct timespec seltime, now;
610 	con *c;
611 	int i;
612 
613 	monotime_ts(&now);
614 	c = TAILQ_FIRST(&tq);
615 
616 	if (c && timespeccmp(&c->c_ts, &now, >))
617 		timespecsub(&c->c_ts, &now, &seltime);
618 	else
619 		timespecclear(&seltime);
620 
621 	while (ppoll(read_wait, maxfd, &seltime, NULL) == -1) {
622 		if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK)
623 			continue;
624 		error("poll error");
625 	}
626 
627 	for (i = 0; i < maxfd; i++) {
628 		if (read_wait[i].revents & (POLLHUP|POLLERR|POLLNVAL))
629 			confree(i);
630 		else if (read_wait[i].revents & (POLLIN|POLLHUP))
631 			conread(i);
632 	}
633 
634 	c = TAILQ_FIRST(&tq);
635 	while (c && timespeccmp(&c->c_ts, &now, <)) {
636 		int s = c->c_fd;
637 
638 		c = TAILQ_NEXT(c, c_link);
639 		conrecycle(s);
640 	}
641 }
642 
643 static void
644 do_one_host(char *host)
645 {
646 	char *name = strnnsep(&host, " \t\n");
647 	int j;
648 
649 	if (name == NULL)
650 		return;
651 	for (j = KT_MIN; j <= KT_MAX; j *= 2) {
652 		if (get_keytypes & j) {
653 			while (ncon >= MAXCON)
654 				conloop();
655 			conalloc(name, *host ? host : name, j);
656 		}
657 	}
658 }
659 
660 static void
661 do_host(char *host)
662 {
663 	char daddr[128];
664 	struct xaddr addr, end_addr;
665 	u_int masklen;
666 
667 	if (host == NULL)
668 		return;
669 	if (addr_pton_cidr(host, &addr, &masklen) != 0) {
670 		/* Assume argument is a hostname */
671 		do_one_host(host);
672 	} else {
673 		/* Argument is a CIDR range */
674 		debug("CIDR range %s", host);
675 		end_addr = addr;
676 		if (addr_host_to_all1s(&end_addr, masklen) != 0)
677 			goto badaddr;
678 		/*
679 		 * Note: we deliberately include the all-zero/ones addresses.
680 		 */
681 		for (;;) {
682 			if (addr_ntop(&addr, daddr, sizeof(daddr)) != 0) {
683  badaddr:
684 				error("Invalid address %s", host);
685 				return;
686 			}
687 			debug("CIDR expand: address %s", daddr);
688 			do_one_host(daddr);
689 			if (addr_cmp(&addr, &end_addr) == 0)
690 				break;
691 			addr_increment(&addr);
692 		};
693 	}
694 }
695 
696 void
697 sshfatal(const char *file, const char *func, int line, int showfunc,
698     LogLevel level, const char *suffix, const char *fmt, ...)
699 {
700 	va_list args;
701 
702 	va_start(args, fmt);
703 	sshlogv(file, func, line, showfunc, level, suffix, fmt, args);
704 	va_end(args);
705 	cleanup_exit(255);
706 }
707 
708 static void
709 usage(void)
710 {
711 	fprintf(stderr,
712 	    "usage: ssh-keyscan [-46cDHv] [-f file] [-O option] [-p port] [-T timeout]\n"
713 	    "                   [-t type] [host | addrlist namelist]\n");
714 	exit(1);
715 }
716 
717 int
718 main(int argc, char **argv)
719 {
720 	int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
721 	int opt, fopt_count = 0, j;
722 	char *tname, *cp, *line = NULL;
723 	size_t linesize = 0;
724 	FILE *fp;
725 
726 	extern int optind;
727 	extern char *optarg;
728 
729 	__progname = ssh_get_progname(argv[0]);
730 	seed_rng();
731 	TAILQ_INIT(&tq);
732 
733 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
734 	sanitise_stdfd();
735 
736 	if (argc <= 1)
737 		usage();
738 
739 	while ((opt = getopt(argc, argv, "cDHv46O:p:T:t:f:")) != -1) {
740 		switch (opt) {
741 		case 'H':
742 			hash_hosts = 1;
743 			break;
744 		case 'c':
745 			get_cert = 1;
746 			break;
747 		case 'D':
748 			print_sshfp = 1;
749 			break;
750 		case 'p':
751 			ssh_port = a2port(optarg);
752 			if (ssh_port <= 0) {
753 				fprintf(stderr, "Bad port '%s'\n", optarg);
754 				exit(1);
755 			}
756 			break;
757 		case 'T':
758 			timeout = convtime(optarg);
759 			if (timeout == -1 || timeout == 0) {
760 				fprintf(stderr, "Bad timeout '%s'\n", optarg);
761 				usage();
762 			}
763 			break;
764 		case 'v':
765 			if (!debug_flag) {
766 				debug_flag = 1;
767 				log_level = SYSLOG_LEVEL_DEBUG1;
768 			}
769 			else if (log_level < SYSLOG_LEVEL_DEBUG3)
770 				log_level++;
771 			else
772 				fatal("Too high debugging level.");
773 			break;
774 		case 'f':
775 			if (strcmp(optarg, "-") == 0)
776 				optarg = NULL;
777 			argv[fopt_count++] = optarg;
778 			break;
779 		case 'O':
780 			/* Maybe other misc options in the future too */
781 			if (strncmp(optarg, "hashalg=", 8) != 0)
782 				fatal("Unsupported -O option");
783 			if ((hashalg = ssh_digest_alg_by_name(
784 			    optarg + 8)) == -1)
785 				fatal("Unsupported hash algorithm");
786 			break;
787 		case 't':
788 			get_keytypes = 0;
789 			tname = strtok(optarg, ",");
790 			while (tname) {
791 				int type = sshkey_type_from_name(tname);
792 
793 				switch (type) {
794 #ifdef WITH_DSA
795 				case KEY_DSA:
796 					get_keytypes |= KT_DSA;
797 					break;
798 #endif
799 				case KEY_ECDSA:
800 					get_keytypes |= KT_ECDSA;
801 					break;
802 				case KEY_RSA:
803 					get_keytypes |= KT_RSA;
804 					break;
805 				case KEY_ED25519:
806 					get_keytypes |= KT_ED25519;
807 					break;
808 				case KEY_XMSS:
809 					get_keytypes |= KT_XMSS;
810 					break;
811 				case KEY_ED25519_SK:
812 					get_keytypes |= KT_ED25519_SK;
813 					break;
814 				case KEY_ECDSA_SK:
815 					get_keytypes |= KT_ECDSA_SK;
816 					break;
817 				case KEY_UNSPEC:
818 				default:
819 					fatal("Unknown key type \"%s\"", tname);
820 				}
821 				tname = strtok(NULL, ",");
822 			}
823 			break;
824 		case '4':
825 			IPv4or6 = AF_INET;
826 			break;
827 		case '6':
828 			IPv4or6 = AF_INET6;
829 			break;
830 		default:
831 			usage();
832 		}
833 	}
834 	if (optind == argc && !fopt_count)
835 		usage();
836 
837 	log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1);
838 
839 	maxfd = fdlim_get(1);
840 	if (maxfd < 0)
841 		fatal("%s: fdlim_get: bad value", __progname);
842 	if (maxfd > MAXMAXFD)
843 		maxfd = MAXMAXFD;
844 	if (MAXCON <= 0)
845 		fatal("%s: not enough file descriptors", __progname);
846 	if (maxfd > fdlim_get(0))
847 		fdlim_set(maxfd);
848 	fdcon = xcalloc(maxfd, sizeof(con));
849 	read_wait = xcalloc(maxfd, sizeof(struct pollfd));
850 	for (j = 0; j < maxfd; j++)
851 		read_wait[j].fd = -1;
852 
853 	for (j = 0; j < fopt_count; j++) {
854 		if (argv[j] == NULL)
855 			fp = stdin;
856 		else if ((fp = fopen(argv[j], "r")) == NULL)
857 			fatal("%s: %s: %s", __progname, argv[j], strerror(errno));
858 
859 		while (getline(&line, &linesize, fp) != -1) {
860 			/* Chomp off trailing whitespace and comments */
861 			if ((cp = strchr(line, '#')) == NULL)
862 				cp = line + strlen(line) - 1;
863 			while (cp >= line) {
864 				if (*cp == ' ' || *cp == '\t' ||
865 				    *cp == '\n' || *cp == '#')
866 					*cp-- = '\0';
867 				else
868 					break;
869 			}
870 
871 			/* Skip empty lines */
872 			if (*line == '\0')
873 				continue;
874 
875 			do_host(line);
876 		}
877 
878 		if (ferror(fp))
879 			fatal("%s: %s: %s", __progname, argv[j], strerror(errno));
880 
881 		fclose(fp);
882 	}
883 	free(line);
884 
885 	while (optind < argc)
886 		do_host(argv[optind++]);
887 
888 	while (ncon > 0)
889 		conloop();
890 
891 	return found_one ? 0 : 1;
892 }
893