rlogind.c revision 29916 
1/*-
2 * Copyright (c) 1983, 1988, 1989, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 *	$Id: rlogind.c,v 1.17 1997/03/28 15:48:16 imp Exp $
34 */
35
36#ifndef lint
37static const char copyright[] =
38"@(#) Copyright (c) 1983, 1988, 1989, 1993\n\
39	The Regents of the University of California.  All rights reserved.\n";
40#endif /* not lint */
41
42#ifndef lint
43static const char sccsid[] = "@(#)rlogind.c	8.1 (Berkeley) 6/4/93";
44#endif /* not lint */
45
46/*
47 * remote login server:
48 *	\0
49 *	remuser\0
50 *	locuser\0
51 *	terminal_type/speed\0
52 *	data
53 */
54
55#define	FD_SETSIZE	16		/* don't need many bits for select */
56#include <sys/types.h>
57#include <sys/param.h>
58#include <sys/stat.h>
59#include <sys/ioctl.h>
60#include <signal.h>
61#include <termios.h>
62
63#include <sys/socket.h>
64#include <netinet/in.h>
65#include <netinet/in_systm.h>
66#include <netinet/ip.h>
67#include <netinet/tcp.h>
68#include <arpa/inet.h>
69#include <netdb.h>
70
71#include <pwd.h>
72#include <syslog.h>
73#include <errno.h>
74#include <stdio.h>
75#include <unistd.h>
76#include <stdlib.h>
77#include <string.h>
78#include <libutil.h>
79#include "pathnames.h"
80
81#ifndef TIOCPKT_WINDOW
82#define TIOCPKT_WINDOW 0x80
83#endif
84
85#ifdef	KERBEROS
86#include <des.h>
87#include <krb.h>
88#define	SECURE_MESSAGE "This rlogin session is using DES encryption for all transmissions.\r\n"
89
90AUTH_DAT	*kdata;
91KTEXT		ticket;
92u_char		auth_buf[sizeof(AUTH_DAT)];
93u_char		tick_buf[sizeof(KTEXT_ST)];
94Key_schedule	schedule;
95int		doencrypt, retval, use_kerberos, vacuous;
96
97#define		ARGSTR			"Dalnkvx"
98#else
99#define		ARGSTR			"Daln"
100#endif	/* KERBEROS */
101
102char	*env[2];
103#define	NMAX 30
104char	lusername[NMAX+1], rusername[NMAX+1];
105static	char term[64] = "TERM=";
106#define	ENVSIZE	(sizeof("TERM=")-1)	/* skip null for concatenation */
107int	keepalive = 1;
108int	check_all = 0;
109int	no_delay;
110
111struct	passwd *pwd;
112
113void	doit __P((int, struct sockaddr_in *));
114int	control __P((int, char *, int));
115void	protocol __P((int, int));
116void	cleanup __P((int));
117void	fatal __P((int, char *, int));
118int	do_rlogin __P((struct sockaddr_in *));
119void	getstr __P((char *, int, char *));
120void	setup_term __P((int));
121int	do_krb_login __P((struct sockaddr_in *));
122void	usage __P((void));
123int	local_domain __P((char *));
124char	*topdomain __P((char *));
125
126int
127main(argc, argv)
128	int argc;
129	char *argv[];
130{
131	extern int __check_rhosts_file;
132	struct sockaddr_in from;
133	int ch, fromlen, on;
134
135	openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
136
137	opterr = 0;
138	while ((ch = getopt(argc, argv, ARGSTR)) != -1)
139		switch (ch) {
140		case 'D':
141			no_delay = 1;
142			break;
143		case 'a':
144			check_all = 1;
145			break;
146		case 'l':
147			__check_rhosts_file = 0;
148			break;
149		case 'n':
150			keepalive = 0;
151			break;
152#ifdef KERBEROS
153		case 'k':
154			use_kerberos = 1;
155			break;
156		case 'v':
157			vacuous = 1;
158			break;
159#ifdef CRYPT
160		case 'x':
161			doencrypt = 1;
162			break;
163#endif
164#endif
165		case '?':
166		default:
167			usage();
168			break;
169		}
170	argc -= optind;
171	argv += optind;
172
173#ifdef	KERBEROS
174	if (use_kerberos && vacuous) {
175		usage();
176		fatal(STDERR_FILENO, "only one of -k and -v allowed", 0);
177	}
178#endif
179	fromlen = sizeof (from);
180	if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
181		syslog(LOG_ERR,"Can't get peer name of remote host: %m");
182		fatal(STDERR_FILENO, "Can't get peer name of remote host", 1);
183	}
184	on = 1;
185	if (keepalive &&
186	    setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0)
187		syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
188	if (no_delay &&
189	    setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
190		syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
191	on = IPTOS_LOWDELAY;
192	if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
193		syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
194
195	doit(0, &from);
196	return 0;
197}
198
199int	child;
200int	netf;
201char	line[MAXPATHLEN];
202int	confirmed;
203
204struct winsize win = { 0, 0, 0, 0 };
205
206
207void
208doit(f, fromp)
209	int f;
210	struct sockaddr_in *fromp;
211{
212	int master, pid, on = 1;
213	int authenticated = 0;
214	register struct hostent *hp;
215	char hostname[2 * MAXHOSTNAMELEN + 1];
216	char c;
217
218	alarm(60);
219	read(f, &c, 1);
220
221	if (c != 0)
222		exit(1);
223#ifdef	KERBEROS
224	if (vacuous)
225		fatal(f, "Remote host requires Kerberos authentication", 0);
226#endif
227
228	alarm(0);
229	fromp->sin_port = ntohs((u_short)fromp->sin_port);
230	hp = gethostbyaddr((char *)&fromp->sin_addr, sizeof(struct in_addr),
231	    fromp->sin_family);
232	if (hp) {
233		(void)strncpy(hostname, hp->h_name, sizeof(hostname));
234	} else {
235		(void)strncpy(hostname, inet_ntoa(fromp->sin_addr), sizeof(hostname));
236	}
237	hostname[sizeof(hostname) - 1] = '\0';
238
239#ifdef	KERBEROS
240	if (use_kerberos) {
241		retval = do_krb_login(fromp);
242		if (retval == 0)
243			authenticated++;
244		else if (retval > 0)
245			fatal(f, krb_err_txt[retval], 0);
246		write(f, &c, 1);
247		confirmed = 1;		/* we sent the null! */
248	} else
249#endif
250	{
251		if (fromp->sin_family != AF_INET ||
252		    fromp->sin_port >= IPPORT_RESERVED ||
253		    fromp->sin_port < IPPORT_RESERVED/2) {
254			syslog(LOG_NOTICE, "Connection from %s on illegal port",
255				inet_ntoa(fromp->sin_addr));
256			fatal(f, "Permission denied", 0);
257		}
258#ifdef IP_OPTIONS
259		{
260		u_char optbuf[BUFSIZ/3];
261		int optsize = sizeof(optbuf), ipproto, i;
262		struct protoent *ip;
263
264		if ((ip = getprotobyname("ip")) != NULL)
265			ipproto = ip->p_proto;
266		else
267			ipproto = IPPROTO_IP;
268		if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
269		    &optsize) == 0 && optsize != 0) {
270			for (i = 0; i < optsize; ) {
271				u_char c = optbuf[i];
272				if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
273					syslog(LOG_NOTICE,
274						"Connection refused from %s with IP option %s",
275						inet_ntoa(fromp->sin_addr),
276						c == IPOPT_LSRR ? "LSRR" : "SSRR");
277					exit(1);
278				}
279				if (c == IPOPT_EOL)
280					break;
281				i += (c == IPOPT_NOP) ? 1 : optbuf[i+1];
282			}
283		}
284		}
285#endif
286		if (do_rlogin(fromp) == 0)
287			authenticated++;
288	}
289	if (confirmed == 0) {
290		write(f, "", 1);
291		confirmed = 1;		/* we sent the null! */
292	}
293#ifdef	KERBEROS
294#ifdef	CRYPT
295	if (doencrypt)
296		(void) des_enc_write(f,
297				     SECURE_MESSAGE,
298				     strlen(SECURE_MESSAGE),
299				     schedule, &kdata->session);
300#endif
301#endif
302	netf = f;
303
304	pid = forkpty(&master, line, NULL, &win);
305	if (pid < 0) {
306		if (errno == ENOENT)
307			fatal(f, "Out of ptys", 0);
308		else
309			fatal(f, "Forkpty", 1);
310	}
311	if (pid == 0) {
312		if (f > 2)	/* f should always be 0, but... */
313			(void) close(f);
314		setup_term(0);
315		 if (*lusername=='-') {
316			syslog(LOG_ERR, "tried to pass user \"%s\" to login",
317			       lusername);
318			fatal(STDERR_FILENO, "invalid user", 0);
319		}
320		if (authenticated) {
321#ifdef	KERBEROS
322			if (use_kerberos && (pwd->pw_uid == 0))
323				syslog(LOG_INFO|LOG_AUTH,
324				    "ROOT Kerberos login from %s.%s@%s on %s\n",
325				    kdata->pname, kdata->pinst, kdata->prealm,
326				    hostname);
327#endif
328
329			execl(_PATH_LOGIN, "login", "-p",
330			    "-h", hostname, "-f", lusername, (char *)NULL);
331		} else
332			execl(_PATH_LOGIN, "login", "-p",
333			    "-h", hostname, lusername, (char *)NULL);
334		fatal(STDERR_FILENO, _PATH_LOGIN, 1);
335		/*NOTREACHED*/
336	}
337#ifdef	CRYPT
338#ifdef	KERBEROS
339	/*
340	 * If encrypted, don't turn on NBIO or the des read/write
341	 * routines will croak.
342	 */
343
344	if (!doencrypt)
345#endif
346#endif
347		ioctl(f, FIONBIO, &on);
348	ioctl(master, FIONBIO, &on);
349	ioctl(master, TIOCPKT, &on);
350	signal(SIGCHLD, cleanup);
351	protocol(f, master);
352	signal(SIGCHLD, SIG_IGN);
353	cleanup(0);
354}
355
356char	magic[2] = { 0377, 0377 };
357char	oobdata[] = {TIOCPKT_WINDOW};
358
359/*
360 * Handle a "control" request (signaled by magic being present)
361 * in the data stream.  For now, we are only willing to handle
362 * window size changes.
363 */
364int
365control(pty, cp, n)
366	int pty;
367	char *cp;
368	int n;
369{
370	struct winsize w;
371
372	if (n < 4+sizeof (w) || cp[2] != 's' || cp[3] != 's')
373		return (0);
374	oobdata[0] &= ~TIOCPKT_WINDOW;	/* we know he heard */
375	bcopy(cp+4, (char *)&w, sizeof(w));
376	w.ws_row = ntohs(w.ws_row);
377	w.ws_col = ntohs(w.ws_col);
378	w.ws_xpixel = ntohs(w.ws_xpixel);
379	w.ws_ypixel = ntohs(w.ws_ypixel);
380	(void)ioctl(pty, TIOCSWINSZ, &w);
381	return (4+sizeof (w));
382}
383
384/*
385 * rlogin "protocol" machine.
386 */
387void
388protocol(f, p)
389	register int f, p;
390{
391	char pibuf[1024+1], fibuf[1024], *pbp, *fbp;
392	register pcc = 0, fcc = 0;
393	int cc, nfd, n;
394	char cntl;
395
396	/*
397	 * Must ignore SIGTTOU, otherwise we'll stop
398	 * when we try and set slave pty's window shape
399	 * (our controlling tty is the master pty).
400	 */
401	(void) signal(SIGTTOU, SIG_IGN);
402	send(f, oobdata, 1, MSG_OOB);	/* indicate new rlogin */
403	if (f > p)
404		nfd = f + 1;
405	else
406		nfd = p + 1;
407	if (nfd > FD_SETSIZE) {
408		syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
409		fatal(f, "internal error (select mask too small)", 0);
410	}
411	for (;;) {
412		fd_set ibits, obits, ebits, *omask;
413
414		FD_ZERO(&ebits);
415		FD_ZERO(&ibits);
416		FD_ZERO(&obits);
417		omask = (fd_set *)NULL;
418		if (fcc) {
419			FD_SET(p, &obits);
420			omask = &obits;
421		} else
422			FD_SET(f, &ibits);
423		if (pcc >= 0)
424			if (pcc) {
425				FD_SET(f, &obits);
426				omask = &obits;
427			} else
428				FD_SET(p, &ibits);
429		FD_SET(p, &ebits);
430		if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
431			if (errno == EINTR)
432				continue;
433			fatal(f, "select", 1);
434		}
435		if (n == 0) {
436			/* shouldn't happen... */
437			sleep(5);
438			continue;
439		}
440#define	pkcontrol(c)	((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
441		if (FD_ISSET(p, &ebits)) {
442			cc = read(p, &cntl, 1);
443			if (cc == 1 && pkcontrol(cntl)) {
444				cntl |= oobdata[0];
445				send(f, &cntl, 1, MSG_OOB);
446				if (cntl & TIOCPKT_FLUSHWRITE) {
447					pcc = 0;
448					FD_CLR(p, &ibits);
449				}
450			}
451		}
452		if (FD_ISSET(f, &ibits)) {
453#ifdef	CRYPT
454#ifdef	KERBEROS
455			if (doencrypt)
456				fcc = des_enc_read(f, fibuf, sizeof(fibuf),
457					schedule, &kdata->session);
458			else
459#endif
460#endif
461				fcc = read(f, fibuf, sizeof(fibuf));
462			if (fcc < 0 && errno == EWOULDBLOCK)
463				fcc = 0;
464			else {
465				register char *cp;
466				int left, n;
467
468				if (fcc <= 0)
469					break;
470				fbp = fibuf;
471
472			top:
473				for (cp = fibuf; cp < fibuf+fcc-1; cp++)
474					if (cp[0] == magic[0] &&
475					    cp[1] == magic[1]) {
476						left = fcc - (cp-fibuf);
477						n = control(p, cp, left);
478						if (n) {
479							left -= n;
480							if (left > 0)
481								bcopy(cp+n, cp, left);
482							fcc -= n;
483							goto top; /* n^2 */
484						}
485					}
486				FD_SET(p, &obits);		/* try write */
487			}
488		}
489
490		if (FD_ISSET(p, &obits) && fcc > 0) {
491			cc = write(p, fbp, fcc);
492			if (cc > 0) {
493				fcc -= cc;
494				fbp += cc;
495			}
496		}
497
498		if (FD_ISSET(p, &ibits)) {
499			pcc = read(p, pibuf, sizeof (pibuf));
500			pbp = pibuf;
501			if (pcc < 0 && errno == EWOULDBLOCK)
502				pcc = 0;
503			else if (pcc <= 0)
504				break;
505			else if (pibuf[0] == 0) {
506				pbp++, pcc--;
507#ifdef	CRYPT
508#ifdef	KERBEROS
509				if (!doencrypt)
510#endif
511#endif
512					FD_SET(f, &obits);	/* try write */
513			} else {
514				if (pkcontrol(pibuf[0])) {
515					pibuf[0] |= oobdata[0];
516					send(f, &pibuf[0], 1, MSG_OOB);
517				}
518				pcc = 0;
519			}
520		}
521		if ((FD_ISSET(f, &obits)) && pcc > 0) {
522#ifdef	CRYPT
523#ifdef	KERBEROS
524			if (doencrypt)
525				cc = des_enc_write(f, pbp, pcc,
526					schedule, &kdata->session);
527			else
528#endif
529#endif
530				cc = write(f, pbp, pcc);
531			if (cc < 0 && errno == EWOULDBLOCK) {
532				/*
533				 * This happens when we try write after read
534				 * from p, but some old kernels balk at large
535				 * writes even when select returns true.
536				 */
537				if (!FD_ISSET(p, &ibits))
538					sleep(5);
539				continue;
540			}
541			if (cc > 0) {
542				pcc -= cc;
543				pbp += cc;
544			}
545		}
546	}
547}
548
549void
550cleanup(signo)
551	int signo;
552{
553	char *p;
554
555	p = line + sizeof(_PATH_DEV) - 1;
556	if (logout(p))
557		logwtmp(p, "", "");
558	(void)chmod(line, 0666);
559	(void)chown(line, 0, 0);
560	*p = 'p';
561	(void)chmod(line, 0666);
562	(void)chown(line, 0, 0);
563	shutdown(netf, 2);
564	exit(1);
565}
566
567void
568fatal(f, msg, syserr)
569	int f;
570	char *msg;
571	int syserr;
572{
573	int len;
574	char buf[BUFSIZ], *bp = buf;
575
576	/*
577	 * Prepend binary one to message if we haven't sent
578	 * the magic null as confirmation.
579	 */
580	if (!confirmed)
581		*bp++ = '\01';		/* error indicator */
582	if (syserr)
583		len = sprintf(bp, "rlogind: %s: %s.\r\n",
584		    msg, strerror(errno));
585	else
586		len = sprintf(bp, "rlogind: %s.\r\n", msg);
587	(void) write(f, buf, bp + len - buf);
588	exit(1);
589}
590
591int
592do_rlogin(dest)
593	struct sockaddr_in *dest;
594{
595	getstr(rusername, sizeof(rusername), "remuser too long");
596	getstr(lusername, sizeof(lusername), "locuser too long");
597	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
598
599	pwd = getpwnam(lusername);
600	if (pwd == NULL)
601		return (-1);
602	/* XXX why don't we syslog() failure? */
603	return (iruserok(dest->sin_addr.s_addr, pwd->pw_uid == 0,
604		rusername, lusername));
605}
606
607void
608getstr(buf, cnt, errmsg)
609	char *buf;
610	int cnt;
611	char *errmsg;
612{
613	char c;
614
615	do {
616		if (read(0, &c, 1) != 1)
617			exit(1);
618		if (--cnt < 0)
619			fatal(STDOUT_FILENO, errmsg, 0);
620		*buf++ = c;
621	} while (c != 0);
622}
623
624extern	char **environ;
625
626void
627setup_term(fd)
628	int fd;
629{
630	register char *cp = index(term+ENVSIZE, '/');
631	char *speed;
632	struct termios tt;
633
634#ifndef notyet
635	tcgetattr(fd, &tt);
636	if (cp) {
637		*cp++ = '\0';
638		speed = cp;
639		cp = index(speed, '/');
640		if (cp)
641			*cp++ = '\0';
642		cfsetspeed(&tt, atoi(speed));
643	}
644
645	tt.c_iflag = TTYDEF_IFLAG;
646	tt.c_oflag = TTYDEF_OFLAG;
647	tt.c_lflag = TTYDEF_LFLAG;
648	tcsetattr(fd, TCSAFLUSH, &tt);
649#else
650	if (cp) {
651		*cp++ = '\0';
652		speed = cp;
653		cp = index(speed, '/');
654		if (cp)
655			*cp++ = '\0';
656		tcgetattr(fd, &tt);
657		cfsetspeed(&tt, atoi(speed));
658		tcsetattr(fd, TCSAFLUSH, &tt);
659	}
660#endif
661
662	env[0] = term;
663	env[1] = 0;
664	environ = env;
665}
666
667#ifdef	KERBEROS
668#define	VERSION_SIZE	9
669
670/*
671 * Do the remote kerberos login to the named host with the
672 * given inet address
673 *
674 * Return 0 on valid authorization
675 * Return -1 on valid authentication, no authorization
676 * Return >0 for error conditions
677 */
678int
679do_krb_login(dest)
680	struct sockaddr_in *dest;
681{
682	int rc;
683	char instance[INST_SZ], version[VERSION_SIZE];
684	long authopts = 0L;	/* !mutual */
685	struct sockaddr_in faddr;
686
687	kdata = (AUTH_DAT *) auth_buf;
688	ticket = (KTEXT) tick_buf;
689
690	instance[0] = '*';
691	instance[1] = '\0';
692
693#ifdef	CRYPT
694	if (doencrypt) {
695		rc = sizeof(faddr);
696		if (getsockname(0, (struct sockaddr *)&faddr, &rc))
697			return (-1);
698		authopts = KOPT_DO_MUTUAL;
699		rc = krb_recvauth(
700			authopts, 0,
701			ticket, "rcmd",
702			instance, dest, &faddr,
703			kdata, "", schedule, version);
704		 des_set_key(&kdata->session, schedule);
705
706	} else
707#endif
708		rc = krb_recvauth(
709			authopts, 0,
710			ticket, "rcmd",
711			instance, dest, (struct sockaddr_in *) 0,
712			kdata, "", NULL, version);
713
714	if (rc != KSUCCESS)
715		return (rc);
716
717	getstr(lusername, sizeof(lusername), "locuser");
718	/* get the "cmd" in the rcmd protocol */
719	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type");
720
721	pwd = getpwnam(lusername);
722	if (pwd == NULL)
723		return (-1);
724
725	/* returns nonzero for no access */
726	if (kuserok(kdata, lusername) != 0)
727		return (-1);
728
729	return (0);
730
731}
732#endif /* KERBEROS */
733
734void
735usage()
736{
737#ifdef KERBEROS
738	syslog(LOG_ERR, "usage: rlogind [-Daln] [-k | -v]");
739#else
740	syslog(LOG_ERR, "usage: rlogind [-Daln]");
741#endif
742}
743
744/*
745 * Check whether host h is in our local domain,
746 * defined as sharing the last two components of the domain part,
747 * or the entire domain part if the local domain has only one component.
748 * If either name is unqualified (contains no '.'),
749 * assume that the host is local, as it will be
750 * interpreted as such.
751 */
752int
753local_domain(h)
754	char *h;
755{
756	char localhost[MAXHOSTNAMELEN];
757	char *p1, *p2;
758
759	localhost[0] = 0;
760	(void) gethostname(localhost, sizeof(localhost));
761	p1 = topdomain(localhost);
762	p2 = topdomain(h);
763	if (p1 == NULL || p2 == NULL || !strcasecmp(p1, p2))
764		return (1);
765	return (0);
766}
767
768char *
769topdomain(h)
770	char *h;
771{
772	register char *p;
773	char *maybe = NULL;
774	int dots = 0;
775
776	for (p = h + strlen(h); p >= h; p--) {
777		if (*p == '.') {
778			if (++dots == 2)
779				return (p);
780			maybe = p;
781		}
782	}
783	return (maybe);
784}
785