1/* $OpenBSD: ssh-keyscan.c,v 1.120 2018/06/06 18:29:18 markus 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 "sshbuf.h"
36#include "sshkey.h"
37#include "cipher.h"
38#include "kex.h"
39#include "compat.h"
40#include "myproposal.h"
41#include "packet.h"
42#include "dispatch.h"
43#include "log.h"
44#include "atomicio.h"
45#include "misc.h"
46#include "hostfile.h"
47#include "ssherr.h"
48#include "ssh_api.h"
49#include "dns.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_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
63#define KT_MIN		KT_DSA
64#define KT_MAX		KT_XMSS
65
66int get_cert = 0;
67int get_keytypes = KT_RSA|KT_ECDSA|KT_ED25519;
68
69int hash_hosts = 0;		/* Hash hostname on output */
70
71int print_sshfp = 0;		/* Print SSHFP records instead of known_hosts */
72
73#define MAXMAXFD 256
74
75/* The number of seconds after which to give up on a TCP connection */
76int timeout = 5;
77
78int maxfd;
79#define MAXCON (maxfd - 10)
80
81extern char *__progname;
82fd_set *read_wait;
83size_t read_wait_nfdset;
84int ncon;
85
86struct ssh *active_state = NULL; /* XXX needed for linking */
87
88/*
89 * Keep a connection structure for each file descriptor.  The state
90 * associated with file descriptor n is held in fdcon[n].
91 */
92typedef struct Connection {
93	u_char c_status;	/* State of connection on this file desc. */
94#define CS_UNUSED 0		/* File descriptor unused */
95#define CS_CON 1		/* Waiting to connect/read greeting */
96#define CS_SIZE 2		/* Waiting to read initial packet size */
97#define CS_KEYS 3		/* Waiting to read public key packet */
98	int c_fd;		/* Quick lookup: c->c_fd == c - fdcon */
99	int c_plen;		/* Packet length field for ssh packet */
100	int c_len;		/* Total bytes which must be read. */
101	int c_off;		/* Length of data read so far. */
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	char *c_data;		/* Data read from this fd */
109	struct ssh *c_ssh;	/* SSH-connection */
110	struct timeval c_tv;	/* Time at which connection gets aborted */
111	TAILQ_ENTRY(Connection) c_link;	/* List of connections in timeout order. */
112} con;
113
114TAILQ_HEAD(conlist, Connection) tq;	/* Timeout Queue */
115con *fdcon;
116
117static void keyprint(con *c, struct sshkey *key);
118
119static int
120fdlim_get(int hard)
121{
122#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
123	struct rlimit rlfd;
124
125	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
126		return (-1);
127	if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY)
128		return SSH_SYSFDMAX;
129	else
130		return hard ? rlfd.rlim_max : rlfd.rlim_cur;
131#else
132	return SSH_SYSFDMAX;
133#endif
134}
135
136static int
137fdlim_set(int lim)
138{
139#if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
140	struct rlimit rlfd;
141#endif
142
143	if (lim <= 0)
144		return (-1);
145#if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
146	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
147		return (-1);
148	rlfd.rlim_cur = lim;
149	if (setrlimit(RLIMIT_NOFILE, &rlfd) < 0)
150		return (-1);
151#elif defined (HAVE_SETDTABLESIZE)
152	setdtablesize(lim);
153#endif
154	return (0);
155}
156
157/*
158 * This is an strsep function that returns a null field for adjacent
159 * separators.  This is the same as the 4.4BSD strsep, but different from the
160 * one in the GNU libc.
161 */
162static char *
163xstrsep(char **str, const char *delim)
164{
165	char *s, *e;
166
167	if (!**str)
168		return (NULL);
169
170	s = *str;
171	e = s + strcspn(s, delim);
172
173	if (*e != '\0')
174		*e++ = '\0';
175	*str = e;
176
177	return (s);
178}
179
180/*
181 * Get the next non-null token (like GNU strsep).  Strsep() will return a
182 * null token for two adjacent separators, so we may have to loop.
183 */
184static char *
185strnnsep(char **stringp, char *delim)
186{
187	char *tok;
188
189	do {
190		tok = xstrsep(stringp, delim);
191	} while (tok && *tok == '\0');
192	return (tok);
193}
194
195
196static int
197key_print_wrapper(struct sshkey *hostkey, struct ssh *ssh)
198{
199	con *c;
200
201	if ((c = ssh_get_app_data(ssh)) != NULL)
202		keyprint(c, hostkey);
203	/* always abort key exchange */
204	return -1;
205}
206
207static int
208ssh2_capable(int remote_major, int remote_minor)
209{
210	switch (remote_major) {
211	case 1:
212		if (remote_minor == 99)
213			return 1;
214		break;
215	case 2:
216		return 1;
217	default:
218		break;
219	}
220	return 0;
221}
222
223static void
224keygrab_ssh2(con *c)
225{
226	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
227	int r;
228
229	switch (c->c_keytype) {
230	case KT_DSA:
231		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
232		    "ssh-dss-cert-v01@openssh.com" : "ssh-dss";
233		break;
234	case KT_RSA:
235		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
236		    "ssh-rsa-cert-v01@openssh.com" : "ssh-rsa";
237		break;
238	case KT_ED25519:
239		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
240		    "ssh-ed25519-cert-v01@openssh.com" : "ssh-ed25519";
241		break;
242	case KT_XMSS:
243		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
244		    "ssh-xmss-cert-v01@openssh.com" : "ssh-xmss@openssh.com";
245		break;
246	case KT_ECDSA:
247		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ?
248		    "ecdsa-sha2-nistp256-cert-v01@openssh.com,"
249		    "ecdsa-sha2-nistp384-cert-v01@openssh.com,"
250		    "ecdsa-sha2-nistp521-cert-v01@openssh.com" :
251		    "ecdsa-sha2-nistp256,"
252		    "ecdsa-sha2-nistp384,"
253		    "ecdsa-sha2-nistp521";
254		break;
255	default:
256		fatal("unknown key type %d", c->c_keytype);
257		break;
258	}
259	if ((r = kex_setup(c->c_ssh, myproposal)) != 0) {
260		free(c->c_ssh);
261		fprintf(stderr, "kex_setup: %s\n", ssh_err(r));
262		exit(1);
263	}
264#ifdef WITH_OPENSSL
265	c->c_ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
266	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
267	c->c_ssh->kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client;
268	c->c_ssh->kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client;
269	c->c_ssh->kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client;
270	c->c_ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
271	c->c_ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
272# ifdef OPENSSL_HAS_ECC
273	c->c_ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
274# endif
275#endif
276	c->c_ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client;
277	ssh_set_verify_host_key_callback(c->c_ssh, key_print_wrapper);
278	/*
279	 * do the key-exchange until an error occurs or until
280	 * the key_print_wrapper() callback sets c_done.
281	 */
282	ssh_dispatch_run(c->c_ssh, DISPATCH_BLOCK, &c->c_done);
283}
284
285static void
286keyprint_one(const char *host, struct sshkey *key)
287{
288	char *hostport;
289	const char *known_host, *hashed;
290
291	if (print_sshfp) {
292		export_dns_rr(host, key, stdout, 0);
293		return;
294	}
295
296	hostport = put_host_port(host, ssh_port);
297	lowercase(hostport);
298	if (hash_hosts && (hashed = host_hash(host, NULL, 0)) == NULL)
299		fatal("host_hash failed");
300	known_host = hash_hosts ? hashed : hostport;
301	if (!get_cert)
302		fprintf(stdout, "%s ", known_host);
303	sshkey_write(key, stdout);
304	fputs("\n", stdout);
305	free(hostport);
306}
307
308static void
309keyprint(con *c, struct sshkey *key)
310{
311	char *hosts = c->c_output_name ? c->c_output_name : c->c_name;
312	char *host, *ohosts;
313
314	if (key == NULL)
315		return;
316	if (get_cert || (!hash_hosts && ssh_port == SSH_DEFAULT_PORT)) {
317		keyprint_one(hosts, key);
318		return;
319	}
320	ohosts = hosts = xstrdup(hosts);
321	while ((host = strsep(&hosts, ",")) != NULL)
322		keyprint_one(host, key);
323	free(ohosts);
324}
325
326static int
327tcpconnect(char *host)
328{
329	struct addrinfo hints, *ai, *aitop;
330	char strport[NI_MAXSERV];
331	int gaierr, s = -1;
332
333	snprintf(strport, sizeof strport, "%d", ssh_port);
334	memset(&hints, 0, sizeof(hints));
335	hints.ai_family = IPv4or6;
336	hints.ai_socktype = SOCK_STREAM;
337	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
338		error("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr));
339		return -1;
340	}
341	for (ai = aitop; ai; ai = ai->ai_next) {
342		s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
343		if (s < 0) {
344			error("socket: %s", strerror(errno));
345			continue;
346		}
347		if (set_nonblock(s) == -1)
348			fatal("%s: set_nonblock(%d)", __func__, s);
349		if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0 &&
350		    errno != EINPROGRESS)
351			error("connect (`%s'): %s", host, strerror(errno));
352		else
353			break;
354		close(s);
355		s = -1;
356	}
357	freeaddrinfo(aitop);
358	return s;
359}
360
361static int
362conalloc(char *iname, char *oname, int keytype)
363{
364	char *namebase, *name, *namelist;
365	int s;
366
367	namebase = namelist = xstrdup(iname);
368
369	do {
370		name = xstrsep(&namelist, ",");
371		if (!name) {
372			free(namebase);
373			return (-1);
374		}
375	} while ((s = tcpconnect(name)) < 0);
376
377	if (s >= maxfd)
378		fatal("conalloc: fdno %d too high", s);
379	if (fdcon[s].c_status)
380		fatal("conalloc: attempt to reuse fdno %d", s);
381
382	debug3("%s: oname %s kt %d", __func__, oname, keytype);
383	fdcon[s].c_fd = s;
384	fdcon[s].c_status = CS_CON;
385	fdcon[s].c_namebase = namebase;
386	fdcon[s].c_name = name;
387	fdcon[s].c_namelist = namelist;
388	fdcon[s].c_output_name = xstrdup(oname);
389	fdcon[s].c_data = (char *) &fdcon[s].c_plen;
390	fdcon[s].c_len = 4;
391	fdcon[s].c_off = 0;
392	fdcon[s].c_keytype = keytype;
393	monotime_tv(&fdcon[s].c_tv);
394	fdcon[s].c_tv.tv_sec += timeout;
395	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
396	FD_SET(s, read_wait);
397	ncon++;
398	return (s);
399}
400
401static void
402confree(int s)
403{
404	if (s >= maxfd || fdcon[s].c_status == CS_UNUSED)
405		fatal("confree: attempt to free bad fdno %d", s);
406	free(fdcon[s].c_namebase);
407	free(fdcon[s].c_output_name);
408	if (fdcon[s].c_status == CS_KEYS)
409		free(fdcon[s].c_data);
410	fdcon[s].c_status = CS_UNUSED;
411	fdcon[s].c_keytype = 0;
412	if (fdcon[s].c_ssh) {
413		ssh_packet_close(fdcon[s].c_ssh);
414		free(fdcon[s].c_ssh);
415		fdcon[s].c_ssh = NULL;
416	} else
417		close(s);
418	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
419	FD_CLR(s, read_wait);
420	ncon--;
421}
422
423static void
424contouch(int s)
425{
426	TAILQ_REMOVE(&tq, &fdcon[s], c_link);
427	monotime_tv(&fdcon[s].c_tv);
428	fdcon[s].c_tv.tv_sec += timeout;
429	TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
430}
431
432static int
433conrecycle(int s)
434{
435	con *c = &fdcon[s];
436	int ret;
437
438	ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
439	confree(s);
440	return (ret);
441}
442
443static void
444congreet(int s)
445{
446	int n = 0, remote_major = 0, remote_minor = 0;
447	char buf[256], *cp;
448	char remote_version[sizeof buf];
449	size_t bufsiz;
450	con *c = &fdcon[s];
451
452	/* send client banner */
453	n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
454	    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2);
455	if (n < 0 || (size_t)n >= sizeof(buf)) {
456		error("snprintf: buffer too small");
457		confree(s);
458		return;
459	}
460	if (atomicio(vwrite, s, buf, n) != (size_t)n) {
461		error("write (%s): %s", c->c_name, strerror(errno));
462		confree(s);
463		return;
464	}
465
466	for (;;) {
467		memset(buf, '\0', sizeof(buf));
468		bufsiz = sizeof(buf);
469		cp = buf;
470		while (bufsiz-- &&
471		    (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') {
472			if (*cp == '\r')
473				*cp = '\n';
474			cp++;
475		}
476		if (n != 1 || strncmp(buf, "SSH-", 4) == 0)
477			break;
478	}
479	if (n == 0) {
480		switch (errno) {
481		case EPIPE:
482			error("%s: Connection closed by remote host", c->c_name);
483			break;
484		case ECONNREFUSED:
485			break;
486		default:
487			error("read (%s): %s", c->c_name, strerror(errno));
488			break;
489		}
490		conrecycle(s);
491		return;
492	}
493	if (*cp != '\n' && *cp != '\r') {
494		error("%s: bad greeting", c->c_name);
495		confree(s);
496		return;
497	}
498	*cp = '\0';
499	if ((c->c_ssh = ssh_packet_set_connection(NULL, s, s)) == NULL)
500		fatal("ssh_packet_set_connection failed");
501	ssh_packet_set_timeout(c->c_ssh, timeout, 1);
502	ssh_set_app_data(c->c_ssh, c);	/* back link */
503	if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
504	    &remote_major, &remote_minor, remote_version) == 3)
505		c->c_ssh->compat = compat_datafellows(remote_version);
506	else
507		c->c_ssh->compat = 0;
508	if (!ssh2_capable(remote_major, remote_minor)) {
509		debug("%s doesn't support ssh2", c->c_name);
510		confree(s);
511		return;
512	}
513	fprintf(stderr, "%c %s:%d %s\n", print_sshfp ? ';' : '#',
514	    c->c_name, ssh_port, chop(buf));
515	keygrab_ssh2(c);
516	confree(s);
517}
518
519static void
520conread(int s)
521{
522	con *c = &fdcon[s];
523	size_t n;
524
525	if (c->c_status == CS_CON) {
526		congreet(s);
527		return;
528	}
529	n = atomicio(read, s, c->c_data + c->c_off, c->c_len - c->c_off);
530	if (n == 0) {
531		error("read (%s): %s", c->c_name, strerror(errno));
532		confree(s);
533		return;
534	}
535	c->c_off += n;
536
537	if (c->c_off == c->c_len)
538		switch (c->c_status) {
539		case CS_SIZE:
540			c->c_plen = htonl(c->c_plen);
541			c->c_len = c->c_plen + 8 - (c->c_plen & 7);
542			c->c_off = 0;
543			c->c_data = xmalloc(c->c_len);
544			c->c_status = CS_KEYS;
545			break;
546		default:
547			fatal("conread: invalid status %d", c->c_status);
548			break;
549		}
550
551	contouch(s);
552}
553
554static void
555conloop(void)
556{
557	struct timeval seltime, now;
558	fd_set *r, *e;
559	con *c;
560	int i;
561
562	monotime_tv(&now);
563	c = TAILQ_FIRST(&tq);
564
565	if (c && (c->c_tv.tv_sec > now.tv_sec ||
566	    (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec > now.tv_usec))) {
567		seltime = c->c_tv;
568		seltime.tv_sec -= now.tv_sec;
569		seltime.tv_usec -= now.tv_usec;
570		if (seltime.tv_usec < 0) {
571			seltime.tv_usec += 1000000;
572			seltime.tv_sec--;
573		}
574	} else
575		timerclear(&seltime);
576
577	r = xcalloc(read_wait_nfdset, sizeof(fd_mask));
578	e = xcalloc(read_wait_nfdset, sizeof(fd_mask));
579	memcpy(r, read_wait, read_wait_nfdset * sizeof(fd_mask));
580	memcpy(e, read_wait, read_wait_nfdset * sizeof(fd_mask));
581
582	while (select(maxfd, r, NULL, e, &seltime) == -1 &&
583	    (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK))
584		;
585
586	for (i = 0; i < maxfd; i++) {
587		if (FD_ISSET(i, e)) {
588			error("%s: exception!", fdcon[i].c_name);
589			confree(i);
590		} else if (FD_ISSET(i, r))
591			conread(i);
592	}
593	free(r);
594	free(e);
595
596	c = TAILQ_FIRST(&tq);
597	while (c && (c->c_tv.tv_sec < now.tv_sec ||
598	    (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec < now.tv_usec))) {
599		int s = c->c_fd;
600
601		c = TAILQ_NEXT(c, c_link);
602		conrecycle(s);
603	}
604}
605
606static void
607do_host(char *host)
608{
609	char *name = strnnsep(&host, " \t\n");
610	int j;
611
612	if (name == NULL)
613		return;
614	for (j = KT_MIN; j <= KT_MAX; j *= 2) {
615		if (get_keytypes & j) {
616			while (ncon >= MAXCON)
617				conloop();
618			conalloc(name, *host ? host : name, j);
619		}
620	}
621}
622
623void
624fatal(const char *fmt,...)
625{
626	va_list args;
627
628	va_start(args, fmt);
629	do_log(SYSLOG_LEVEL_FATAL, fmt, args);
630	va_end(args);
631	exit(255);
632}
633
634static void
635usage(void)
636{
637	fprintf(stderr,
638	    "usage: %s [-46cDHv] [-f file] [-p port] [-T timeout] [-t type]\n"
639	    "\t\t   [host | addrlist namelist]\n",
640	    __progname);
641	exit(1);
642}
643
644int
645main(int argc, char **argv)
646{
647	int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
648	int opt, fopt_count = 0, j;
649	char *tname, *cp, *line = NULL;
650	size_t linesize = 0;
651	FILE *fp;
652
653	extern int optind;
654	extern char *optarg;
655
656	ssh_malloc_init();	/* must be called before any mallocs */
657	__progname = ssh_get_progname(argv[0]);
658	seed_rng();
659	TAILQ_INIT(&tq);
660
661	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
662	sanitise_stdfd();
663
664	if (argc <= 1)
665		usage();
666
667	while ((opt = getopt(argc, argv, "cDHv46p:T:t:f:")) != -1) {
668		switch (opt) {
669		case 'H':
670			hash_hosts = 1;
671			break;
672		case 'c':
673			get_cert = 1;
674			break;
675		case 'D':
676			print_sshfp = 1;
677			break;
678		case 'p':
679			ssh_port = a2port(optarg);
680			if (ssh_port <= 0) {
681				fprintf(stderr, "Bad port '%s'\n", optarg);
682				exit(1);
683			}
684			break;
685		case 'T':
686			timeout = convtime(optarg);
687			if (timeout == -1 || timeout == 0) {
688				fprintf(stderr, "Bad timeout '%s'\n", optarg);
689				usage();
690			}
691			break;
692		case 'v':
693			if (!debug_flag) {
694				debug_flag = 1;
695				log_level = SYSLOG_LEVEL_DEBUG1;
696			}
697			else if (log_level < SYSLOG_LEVEL_DEBUG3)
698				log_level++;
699			else
700				fatal("Too high debugging level.");
701			break;
702		case 'f':
703			if (strcmp(optarg, "-") == 0)
704				optarg = NULL;
705			argv[fopt_count++] = optarg;
706			break;
707		case 't':
708			get_keytypes = 0;
709			tname = strtok(optarg, ",");
710			while (tname) {
711				int type = sshkey_type_from_name(tname);
712
713				switch (type) {
714				case KEY_DSA:
715					get_keytypes |= KT_DSA;
716					break;
717				case KEY_ECDSA:
718					get_keytypes |= KT_ECDSA;
719					break;
720				case KEY_RSA:
721					get_keytypes |= KT_RSA;
722					break;
723				case KEY_ED25519:
724					get_keytypes |= KT_ED25519;
725					break;
726				case KEY_XMSS:
727					get_keytypes |= KT_XMSS;
728					break;
729				case KEY_UNSPEC:
730				default:
731					fatal("Unknown key type \"%s\"", tname);
732				}
733				tname = strtok(NULL, ",");
734			}
735			break;
736		case '4':
737			IPv4or6 = AF_INET;
738			break;
739		case '6':
740			IPv4or6 = AF_INET6;
741			break;
742		case '?':
743		default:
744			usage();
745		}
746	}
747	if (optind == argc && !fopt_count)
748		usage();
749
750	log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1);
751
752	maxfd = fdlim_get(1);
753	if (maxfd < 0)
754		fatal("%s: fdlim_get: bad value", __progname);
755	if (maxfd > MAXMAXFD)
756		maxfd = MAXMAXFD;
757	if (MAXCON <= 0)
758		fatal("%s: not enough file descriptors", __progname);
759	if (maxfd > fdlim_get(0))
760		fdlim_set(maxfd);
761	fdcon = xcalloc(maxfd, sizeof(con));
762
763	read_wait_nfdset = howmany(maxfd, NFDBITS);
764	read_wait = xcalloc(read_wait_nfdset, sizeof(fd_mask));
765
766	for (j = 0; j < fopt_count; j++) {
767		if (argv[j] == NULL)
768			fp = stdin;
769		else if ((fp = fopen(argv[j], "r")) == NULL)
770			fatal("%s: %s: %s", __progname, argv[j],
771			    strerror(errno));
772
773		while (getline(&line, &linesize, fp) != -1) {
774			/* Chomp off trailing whitespace and comments */
775			if ((cp = strchr(line, '#')) == NULL)
776				cp = line + strlen(line) - 1;
777			while (cp >= line) {
778				if (*cp == ' ' || *cp == '\t' ||
779				    *cp == '\n' || *cp == '#')
780					*cp-- = '\0';
781				else
782					break;
783			}
784
785			/* Skip empty lines */
786			if (*line == '\0')
787				continue;
788
789			do_host(line);
790		}
791
792		if (ferror(fp))
793			fatal("%s: %s: %s", __progname, argv[j],
794			    strerror(errno));
795
796		fclose(fp);
797	}
798	free(line);
799
800	while (optind < argc)
801		do_host(argv[optind++]);
802
803	while (ncon > 0)
804		conloop();
805
806	return (0);
807}
808