ssh-keyscan.c revision 295367 
1/* $OpenBSD: ssh-keyscan.c,v 1.101 2015/04/10 00:08:55 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#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 "ssh1.h"
36#include "sshbuf.h"
37#include "sshkey.h"
38#include "cipher.h"
39#include "kex.h"
40#include "compat.h"
41#include "myproposal.h"
42#include "packet.h"
43#include "dispatch.h"
44#include "log.h"
45#include "atomicio.h"
46#include "misc.h"
47#include "hostfile.h"
48#include "ssherr.h"
49#include "ssh_api.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. */
53int IPv4or6 = AF_UNSPEC;
54
55int ssh_port = SSH_DEFAULT_PORT;
56
57#define KT_RSA1		1
58#define KT_DSA		2
59#define KT_RSA		4
60#define KT_ECDSA	8
61#define KT_ED25519	16
62
63int get_keytypes = KT_RSA|KT_ECDSA|KT_ED25519;
64
65int hash_hosts = 0;		/* Hash hostname on output */
66
67#define MAXMAXFD 256
68
69/* The number of seconds after which to give up on a TCP connection */
70int timeout = 5;
71
72int maxfd;
73#define MAXCON (maxfd - 10)
74
75extern char *__progname;
76fd_set *read_wait;
77size_t read_wait_nfdset;
78int ncon;
79
80struct ssh *active_state = NULL; /* XXX needed for linking */
81
82/*
83 * Keep a connection structure for each file descriptor.  The state
84 * associated with file descriptor n is held in fdcon[n].
85 */
86typedef struct Connection {
87	u_char c_status;	/* State of connection on this file desc. */
88#define CS_UNUSED 0		/* File descriptor unused */
89#define CS_CON 1		/* Waiting to connect/read greeting */
90#define CS_SIZE 2		/* Waiting to read initial packet size */
91#define CS_KEYS 3		/* Waiting to read public key packet */
92	int c_fd;		/* Quick lookup: c->c_fd == c - fdcon */
93	int c_plen;		/* Packet length field for ssh packet */
94	int c_len;		/* Total bytes which must be read. */
95	int c_off;		/* Length of data read so far. */
96	int c_keytype;		/* Only one of KT_RSA1, KT_DSA, or KT_RSA */
97	sig_atomic_t c_done;	/* SSH2 done */
98	char *c_namebase;	/* Address to free for c_name and c_namelist */
99	char *c_name;		/* Hostname of connection for errors */
100	char *c_namelist;	/* Pointer to other possible addresses */
101	char *c_output_name;	/* Hostname of connection for output */
102	char *c_data;		/* Data read from this fd */
103	struct ssh *c_ssh;	/* SSH-connection */
104	struct timeval c_tv;	/* Time at which connection gets aborted */
105	TAILQ_ENTRY(Connection) c_link;	/* List of connections in timeout order. */
106} con;
107
108TAILQ_HEAD(conlist, Connection) tq;	/* Timeout Queue */
109con *fdcon;
110
111static void keyprint(con *c, struct sshkey *key);
112
113static int
114fdlim_get(int hard)
115{
116#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
117	struct rlimit rlfd;
118
119	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
120		return (-1);
121	if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY)
122		return SSH_SYSFDMAX;
123	else
124		return hard ? rlfd.rlim_max : rlfd.rlim_cur;
125#else
126	return SSH_SYSFDMAX;
127#endif
128}
129
130static int
131fdlim_set(int lim)
132{
133#if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
134	struct rlimit rlfd;
135#endif
136
137	if (lim <= 0)
138		return (-1);
139#if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
140	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
141		return (-1);
142	rlfd.rlim_cur = lim;
143	if (setrlimit(RLIMIT_NOFILE, &rlfd) < 0)
144		return (-1);
145#elif defined (HAVE_SETDTABLESIZE)
146	setdtablesize(lim);
147#endif
148	return (0);
149}
150
151/*
152 * This is an strsep function that returns a null field for adjacent
153 * separators.  This is the same as the 4.4BSD strsep, but different from the
154 * one in the GNU libc.
155 */
156static char *
157xstrsep(char **str, const char *delim)
158{
159	char *s, *e;
160
161	if (!**str)
162		return (NULL);
163
164	s = *str;
165	e = s + strcspn(s, delim);
166
167	if (*e != '\0')
168		*e++ = '\0';
169	*str = e;
170
171	return (s);
172}
173
174/*
175 * Get the next non-null token (like GNU strsep).  Strsep() will return a
176 * null token for two adjacent separators, so we may have to loop.
177 */
178static char *
179strnnsep(char **stringp, char *delim)
180{
181	char *tok;
182
183	do {
184		tok = xstrsep(stringp, delim);
185	} while (tok && *tok == '\0');
186	return (tok);
187}
188
189#ifdef WITH_SSH1
190static struct sshkey *
191keygrab_ssh1(con *c)
192{
193	static struct sshkey *rsa;
194	static struct sshbuf *msg;
195	int r;
196	u_char type;
197
198	if (rsa == NULL) {
199		if ((rsa = sshkey_new(KEY_RSA1)) == NULL) {
200			error("%s: sshkey_new failed", __func__);
201			return NULL;
202		}
203		if ((msg = sshbuf_new()) == NULL)
204			fatal("%s: sshbuf_new failed", __func__);
205	}
206	if ((r = sshbuf_put(msg, c->c_data, c->c_plen)) != 0 ||
207	    (r = sshbuf_consume(msg, 8 - (c->c_plen & 7))) != 0 || /* padding */
208	    (r = sshbuf_get_u8(msg, &type)) != 0)
209		goto buf_err;
210	if (type != (int) SSH_SMSG_PUBLIC_KEY) {
211		error("%s: invalid packet type", c->c_name);
212		sshbuf_reset(msg);
213		return NULL;
214	}
215	if ((r = sshbuf_consume(msg, 8)) != 0 || /* cookie */
216	    /* server key */
217	    (r = sshbuf_get_u32(msg, NULL)) != 0 ||
218	    (r = sshbuf_get_bignum1(msg, NULL)) != 0 ||
219	    (r = sshbuf_get_bignum1(msg, NULL)) != 0 ||
220	    /* host key */
221	    (r = sshbuf_get_u32(msg, NULL)) != 0 ||
222	    (r = sshbuf_get_bignum1(msg, rsa->rsa->e)) != 0 ||
223	    (r = sshbuf_get_bignum1(msg, rsa->rsa->n)) != 0) {
224 buf_err:
225		error("%s: buffer error: %s", __func__, ssh_err(r));
226		sshbuf_reset(msg);
227		return NULL;
228	}
229
230	sshbuf_reset(msg);
231
232	return (rsa);
233}
234#endif
235
236static int
237key_print_wrapper(struct sshkey *hostkey, struct ssh *ssh)
238{
239	con *c;
240
241	if ((c = ssh_get_app_data(ssh)) != NULL)
242		keyprint(c, hostkey);
243	/* always abort key exchange */
244	return -1;
245}
246
247static int
248ssh2_capable(int remote_major, int remote_minor)
249{
250	switch (remote_major) {
251	case 1:
252		if (remote_minor == 99)
253			return 1;
254		break;
255	case 2:
256		return 1;
257	default:
258		break;
259	}
260	return 0;
261}
262
263static void
264keygrab_ssh2(con *c)
265{
266	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
267	int r;
268
269	enable_compat20();
270	myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
271	    c->c_keytype == KT_DSA ?  "ssh-dss" :
272	    (c->c_keytype == KT_RSA ? "ssh-rsa" :
273	    (c->c_keytype == KT_ED25519 ? "ssh-ed25519" :
274	    "ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521"));
275	if ((r = kex_setup(c->c_ssh, myproposal)) != 0) {
276		free(c->c_ssh);
277		fprintf(stderr, "kex_setup: %s\n", ssh_err(r));
278		exit(1);
279	}
280#ifdef WITH_OPENSSL
281	c->c_ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
282	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
283	c->c_ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
284	c->c_ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
285# ifdef OPENSSL_HAS_ECC
286	c->c_ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
287# endif
288#endif
289	c->c_ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client;
290	ssh_set_verify_host_key_callback(c->c_ssh, key_print_wrapper);
291	/*
292	 * do the key-exchange until an error occurs or until
293	 * the key_print_wrapper() callback sets c_done.
294	 */
295	ssh_dispatch_run(c->c_ssh, DISPATCH_BLOCK, &c->c_done, c->c_ssh);
296}
297
298static void
299keyprint(con *c, struct sshkey *key)
300{
301	char *host = c->c_output_name ? c->c_output_name : c->c_name;
302	char *hostport = NULL;
303
304	if (!key)
305		return;
306	if (hash_hosts && (host = host_hash(host, NULL, 0)) == NULL)
307		fatal("host_hash failed");
308
309	hostport = put_host_port(host, ssh_port);
310	fprintf(stdout, "%s ", hostport);
311	sshkey_write(key, stdout);
312	fputs("\n", stdout);
313	free(hostport);
314}
315
316static int
317tcpconnect(char *host)
318{
319	struct addrinfo hints, *ai, *aitop;
320	char strport[NI_MAXSERV];
321	int gaierr, s = -1;
322
323	snprintf(strport, sizeof strport, "%d", ssh_port);
324	memset(&hints, 0, sizeof(hints));
325	hints.ai_family = IPv4or6;
326	hints.ai_socktype = SOCK_STREAM;
327	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
328		error("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr));
329		return -1;
330	}
331	for (ai = aitop; ai; ai = ai->ai_next) {
332		s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
333		if (s < 0) {
334			error("socket: %s", strerror(errno));
335			continue;
336		}
337		if (set_nonblock(s) == -1)
338			fatal("%s: set_nonblock(%d)", __func__, s);
339		if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0 &&
340		    errno != EINPROGRESS)
341			error("connect (`%s'): %s", host, strerror(errno));
342		else
343			break;
344		close(s);
345		s = -1;
346	}
347	freeaddrinfo(aitop);
348	return s;
349}
350
351static int
352conalloc(char *iname, char *oname, int keytype)
353{
354	char *namebase, *name, *namelist;
355	int s;
356
357	namebase = namelist = xstrdup(iname);
358
359	do {
360		name = xstrsep(&namelist, ",");
361		if (!name) {
362			free(namebase);
363			return (-1);
364		}
365	} while ((s = tcpconnect(name)) < 0);
366
367	if (s >= maxfd)
368		fatal("conalloc: fdno %d too high", s);
369	if (fdcon[s].c_status)
370		fatal("conalloc: attempt to reuse fdno %d", s);
371
372	fdcon[s].c_fd = s;
373	fdcon[s].c_status = CS_CON;
374	fdcon[s].c_namebase = namebase;
375	fdcon[s].c_name = name;
376	fdcon[s].c_namelist = namelist;
377	fdcon[s].c_output_name = xstrdup(oname);
378	fdcon[s].c_data = (char *) &fdcon[s].c_plen;
379	fdcon[s].c_len = 4;
380	fdcon[s].c_off = 0;
381	fdcon[s].c_keytype = keytype;
382	gettimeofday(&fdcon[s].c_tv, NULL);
383	fdcon[s].c_tv.tv_sec += timeout;
384	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
385	FD_SET(s, read_wait);
386	ncon++;
387	return (s);
388}
389
390static void
391confree(int s)
392{
393	if (s >= maxfd || fdcon[s].c_status == CS_UNUSED)
394		fatal("confree: attempt to free bad fdno %d", s);
395	close(s);
396	free(fdcon[s].c_namebase);
397	free(fdcon[s].c_output_name);
398	if (fdcon[s].c_status == CS_KEYS)
399		free(fdcon[s].c_data);
400	fdcon[s].c_status = CS_UNUSED;
401	fdcon[s].c_keytype = 0;
402	if (fdcon[s].c_ssh) {
403		ssh_packet_close(fdcon[s].c_ssh);
404		free(fdcon[s].c_ssh);
405		fdcon[s].c_ssh = NULL;
406	}
407	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
408	FD_CLR(s, read_wait);
409	ncon--;
410}
411
412static void
413contouch(int s)
414{
415	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
416	gettimeofday(&fdcon[s].c_tv, NULL);
417	fdcon[s].c_tv.tv_sec += timeout;
418	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
419}
420
421static int
422conrecycle(int s)
423{
424	con *c = &fdcon[s];
425	int ret;
426
427	ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
428	confree(s);
429	return (ret);
430}
431
432static void
433congreet(int s)
434{
435	int n = 0, remote_major = 0, remote_minor = 0;
436	char buf[256], *cp;
437	char remote_version[sizeof buf];
438	size_t bufsiz;
439	con *c = &fdcon[s];
440
441	for (;;) {
442		memset(buf, '\0', sizeof(buf));
443		bufsiz = sizeof(buf);
444		cp = buf;
445		while (bufsiz-- &&
446		    (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') {
447			if (*cp == '\r')
448				*cp = '\n';
449			cp++;
450		}
451		if (n != 1 || strncmp(buf, "SSH-", 4) == 0)
452			break;
453	}
454	if (n == 0) {
455		switch (errno) {
456		case EPIPE:
457			error("%s: Connection closed by remote host", c->c_name);
458			break;
459		case ECONNREFUSED:
460			break;
461		default:
462			error("read (%s): %s", c->c_name, strerror(errno));
463			break;
464		}
465		conrecycle(s);
466		return;
467	}
468	if (*cp != '\n' && *cp != '\r') {
469		error("%s: bad greeting", c->c_name);
470		confree(s);
471		return;
472	}
473	*cp = '\0';
474	if ((c->c_ssh = ssh_packet_set_connection(NULL, s, s)) == NULL)
475		fatal("ssh_packet_set_connection failed");
476	ssh_packet_set_timeout(c->c_ssh, timeout, 1);
477	ssh_set_app_data(c->c_ssh, c);	/* back link */
478	if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
479	    &remote_major, &remote_minor, remote_version) == 3)
480		c->c_ssh->compat = compat_datafellows(remote_version);
481	else
482		c->c_ssh->compat = 0;
483	if (c->c_keytype != KT_RSA1) {
484		if (!ssh2_capable(remote_major, remote_minor)) {
485			debug("%s doesn't support ssh2", c->c_name);
486			confree(s);
487			return;
488		}
489	} else if (remote_major != 1) {
490		debug("%s doesn't support ssh1", c->c_name);
491		confree(s);
492		return;
493	}
494	fprintf(stderr, "# %s:%d %s\n", c->c_name, ssh_port, chop(buf));
495	n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
496	    c->c_keytype == KT_RSA1? PROTOCOL_MAJOR_1 : PROTOCOL_MAJOR_2,
497	    c->c_keytype == KT_RSA1? PROTOCOL_MINOR_1 : PROTOCOL_MINOR_2);
498	if (n < 0 || (size_t)n >= sizeof(buf)) {
499		error("snprintf: buffer too small");
500		confree(s);
501		return;
502	}
503	if (atomicio(vwrite, s, buf, n) != (size_t)n) {
504		error("write (%s): %s", c->c_name, strerror(errno));
505		confree(s);
506		return;
507	}
508	if (c->c_keytype != KT_RSA1) {
509		keygrab_ssh2(c);
510		confree(s);
511		return;
512	}
513	c->c_status = CS_SIZE;
514	contouch(s);
515}
516
517static void
518conread(int s)
519{
520	con *c = &fdcon[s];
521	size_t n;
522
523	if (c->c_status == CS_CON) {
524		congreet(s);
525		return;
526	}
527	n = atomicio(read, s, c->c_data + c->c_off, c->c_len - c->c_off);
528	if (n == 0) {
529		error("read (%s): %s", c->c_name, strerror(errno));
530		confree(s);
531		return;
532	}
533	c->c_off += n;
534
535	if (c->c_off == c->c_len)
536		switch (c->c_status) {
537		case CS_SIZE:
538			c->c_plen = htonl(c->c_plen);
539			c->c_len = c->c_plen + 8 - (c->c_plen & 7);
540			c->c_off = 0;
541			c->c_data = xmalloc(c->c_len);
542			c->c_status = CS_KEYS;
543			break;
544#ifdef WITH_SSH1
545		case CS_KEYS:
546			keyprint(c, keygrab_ssh1(c));
547			confree(s);
548			return;
549#endif
550		default:
551			fatal("conread: invalid status %d", c->c_status);
552			break;
553		}
554
555	contouch(s);
556}
557
558static void
559conloop(void)
560{
561	struct timeval seltime, now;
562	fd_set *r, *e;
563	con *c;
564	int i;
565
566	gettimeofday(&now, NULL);
567	c = TAILQ_FIRST(&tq);
568
569	if (c && (c->c_tv.tv_sec > now.tv_sec ||
570	    (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec > now.tv_usec))) {
571		seltime = c->c_tv;
572		seltime.tv_sec -= now.tv_sec;
573		seltime.tv_usec -= now.tv_usec;
574		if (seltime.tv_usec < 0) {
575			seltime.tv_usec += 1000000;
576			seltime.tv_sec--;
577		}
578	} else
579		timerclear(&seltime);
580
581	r = xcalloc(read_wait_nfdset, sizeof(fd_mask));
582	e = xcalloc(read_wait_nfdset, sizeof(fd_mask));
583	memcpy(r, read_wait, read_wait_nfdset * sizeof(fd_mask));
584	memcpy(e, read_wait, read_wait_nfdset * sizeof(fd_mask));
585
586	while (select(maxfd, r, NULL, e, &seltime) == -1 &&
587	    (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK))
588		;
589
590	for (i = 0; i < maxfd; i++) {
591		if (FD_ISSET(i, e)) {
592			error("%s: exception!", fdcon[i].c_name);
593			confree(i);
594		} else if (FD_ISSET(i, r))
595			conread(i);
596	}
597	free(r);
598	free(e);
599
600	c = TAILQ_FIRST(&tq);
601	while (c && (c->c_tv.tv_sec < now.tv_sec ||
602	    (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec < now.tv_usec))) {
603		int s = c->c_fd;
604
605		c = TAILQ_NEXT(c, c_link);
606		conrecycle(s);
607	}
608}
609
610static void
611do_host(char *host)
612{
613	char *name = strnnsep(&host, " \t\n");
614	int j;
615
616	if (name == NULL)
617		return;
618	for (j = KT_RSA1; j <= KT_ED25519; j *= 2) {
619		if (get_keytypes & j) {
620			while (ncon >= MAXCON)
621				conloop();
622			conalloc(name, *host ? host : name, j);
623		}
624	}
625}
626
627void
628fatal(const char *fmt,...)
629{
630	va_list args;
631
632	va_start(args, fmt);
633	do_log(SYSLOG_LEVEL_FATAL, fmt, args);
634	va_end(args);
635	exit(255);
636}
637
638static void
639usage(void)
640{
641	fprintf(stderr,
642	    "usage: %s [-46Hv] [-f file] [-p port] [-T timeout] [-t type]\n"
643	    "\t\t   [host | addrlist namelist] ...\n",
644	    __progname);
645	exit(1);
646}
647
648int
649main(int argc, char **argv)
650{
651	int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
652	int opt, fopt_count = 0, j;
653	char *tname, *cp, line[NI_MAXHOST];
654	FILE *fp;
655	u_long linenum;
656
657	extern int optind;
658	extern char *optarg;
659
660	__progname = ssh_get_progname(argv[0]);
661	seed_rng();
662	TAILQ_INIT(&tq);
663
664	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
665	sanitise_stdfd();
666
667	if (argc <= 1)
668		usage();
669
670	while ((opt = getopt(argc, argv, "Hv46p:T:t:f:")) != -1) {
671		switch (opt) {
672		case 'H':
673			hash_hosts = 1;
674			break;
675		case 'p':
676			ssh_port = a2port(optarg);
677			if (ssh_port <= 0) {
678				fprintf(stderr, "Bad port '%s'\n", optarg);
679				exit(1);
680			}
681			break;
682		case 'T':
683			timeout = convtime(optarg);
684			if (timeout == -1 || timeout == 0) {
685				fprintf(stderr, "Bad timeout '%s'\n", optarg);
686				usage();
687			}
688			break;
689		case 'v':
690			if (!debug_flag) {
691				debug_flag = 1;
692				log_level = SYSLOG_LEVEL_DEBUG1;
693			}
694			else if (log_level < SYSLOG_LEVEL_DEBUG3)
695				log_level++;
696			else
697				fatal("Too high debugging level.");
698			break;
699		case 'f':
700			if (strcmp(optarg, "-") == 0)
701				optarg = NULL;
702			argv[fopt_count++] = optarg;
703			break;
704		case 't':
705			get_keytypes = 0;
706			tname = strtok(optarg, ",");
707			while (tname) {
708				int type = sshkey_type_from_name(tname);
709				switch (type) {
710				case KEY_RSA1:
711					get_keytypes |= KT_RSA1;
712					break;
713				case KEY_DSA:
714					get_keytypes |= KT_DSA;
715					break;
716				case KEY_ECDSA:
717					get_keytypes |= KT_ECDSA;
718					break;
719				case KEY_RSA:
720					get_keytypes |= KT_RSA;
721					break;
722				case KEY_ED25519:
723					get_keytypes |= KT_ED25519;
724					break;
725				case KEY_UNSPEC:
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
758	read_wait_nfdset = howmany(maxfd, NFDBITS);
759	read_wait = xcalloc(read_wait_nfdset, sizeof(fd_mask));
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],
766			    strerror(errno));
767		linenum = 0;
768
769		while (read_keyfile_line(fp,
770		    argv[j] == NULL ? "(stdin)" : argv[j], line, sizeof(line),
771		    &linenum) != -1) {
772			/* Chomp off trailing whitespace and comments */
773			if ((cp = strchr(line, '#')) == NULL)
774				cp = line + strlen(line) - 1;
775			while (cp >= line) {
776				if (*cp == ' ' || *cp == '\t' ||
777				    *cp == '\n' || *cp == '#')
778					*cp-- = '\0';
779				else
780					break;
781			}
782
783			/* Skip empty lines */
784			if (*line == '\0')
785				continue;
786
787			do_host(line);
788		}
789
790		if (ferror(fp))
791			fatal("%s: %s: %s", __progname, argv[j],
792			    strerror(errno));
793
794		fclose(fp);
795	}
796
797	while (optind < argc)
798		do_host(argv[optind++]);
799
800	while (ncon > 0)
801		conloop();
802
803	return (0);
804}
805