rlogind.c revision 31405 
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
34#ifndef lint
35static const char copyright[] =
36"@(#) Copyright (c) 1983, 1988, 1989, 1993\n\
37	The Regents of the University of California.  All rights reserved.\n";
38#endif /* not lint */
39
40#ifndef lint
41#if 0
42static const char sccsid[] = "@(#)rlogind.c	8.1 (Berkeley) 6/4/93";
43#endif
44static const char rcsid[] =
45	"$Id$";
46#endif /* not lint */
47
48/*
49 * remote login server:
50 *	\0
51 *	remuser\0
52 *	locuser\0
53 *	terminal_type/speed\0
54 *	data
55 */
56
57#define	FD_SETSIZE	16		/* don't need many bits for select */
58#include <sys/types.h>
59#include <sys/param.h>
60#include <sys/stat.h>
61#include <sys/ioctl.h>
62#include <signal.h>
63#include <termios.h>
64
65#include <sys/socket.h>
66#include <netinet/in.h>
67#include <netinet/in_systm.h>
68#include <netinet/ip.h>
69#include <netinet/tcp.h>
70#include <arpa/inet.h>
71#include <netdb.h>
72
73#include <errno.h>
74#include <libutil.h>
75#include <pwd.h>
76#include <syslog.h>
77#include <stdio.h>
78#include <stdlib.h>
79#include <string.h>
80#include <unistd.h>
81#include "pathnames.h"
82
83#ifndef TIOCPKT_WINDOW
84#define TIOCPKT_WINDOW 0x80
85#endif
86
87#ifdef	KERBEROS
88#include <des.h>
89#include <krb.h>
90#define	SECURE_MESSAGE "This rlogin session is using DES encryption for all transmissions.\r\n"
91
92AUTH_DAT	*kdata;
93KTEXT		ticket;
94u_char		auth_buf[sizeof(AUTH_DAT)];
95u_char		tick_buf[sizeof(KTEXT_ST)];
96Key_schedule	schedule;
97int		doencrypt, retval, use_kerberos, vacuous;
98
99#define		ARGSTR			"Dalnkvx"
100#else
101#define		ARGSTR			"Daln"
102#endif	/* KERBEROS */
103
104char	*env[2];
105#define	NMAX 30
106char	lusername[NMAX+1], rusername[NMAX+1];
107static	char term[64] = "TERM=";
108#define	ENVSIZE	(sizeof("TERM=")-1)	/* skip null for concatenation */
109int	keepalive = 1;
110int	check_all = 0;
111int	no_delay;
112
113struct	passwd *pwd;
114
115void	doit __P((int, struct sockaddr_in *));
116int	control __P((int, char *, int));
117void	protocol __P((int, int));
118void	cleanup __P((int));
119void	fatal __P((int, char *, int));
120int	do_rlogin __P((struct sockaddr_in *));
121void	getstr __P((char *, int, char *));
122void	setup_term __P((int));
123int	do_krb_login __P((struct sockaddr_in *));
124void	usage __P((void));
125int	local_domain __P((char *));
126char	*topdomain __P((char *));
127
128int
129main(argc, argv)
130	int argc;
131	char *argv[];
132{
133	extern int __check_rhosts_file;
134	struct sockaddr_in from;
135	int ch, fromlen, on;
136
137	openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
138
139	opterr = 0;
140	while ((ch = getopt(argc, argv, ARGSTR)) != -1)
141		switch (ch) {
142		case 'D':
143			no_delay = 1;
144			break;
145		case 'a':
146			check_all = 1;
147			break;
148		case 'l':
149			__check_rhosts_file = 0;
150			break;
151		case 'n':
152			keepalive = 0;
153			break;
154#ifdef KERBEROS
155		case 'k':
156			use_kerberos = 1;
157			break;
158		case 'v':
159			vacuous = 1;
160			break;
161#ifdef CRYPT
162		case 'x':
163			doencrypt = 1;
164			break;
165#endif
166#endif
167		case '?':
168		default:
169			usage();
170			break;
171		}
172	argc -= optind;
173	argv += optind;
174
175#ifdef	KERBEROS
176	if (use_kerberos && vacuous) {
177		usage();
178		fatal(STDERR_FILENO, "only one of -k and -v allowed", 0);
179	}
180#endif
181	fromlen = sizeof (from);
182	if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
183		syslog(LOG_ERR,"Can't get peer name of remote host: %m");
184		fatal(STDERR_FILENO, "Can't get peer name of remote host", 1);
185	}
186	on = 1;
187	if (keepalive &&
188	    setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0)
189		syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
190	if (no_delay &&
191	    setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
192		syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
193	on = IPTOS_LOWDELAY;
194	if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
195		syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
196
197	doit(0, &from);
198	return 0;
199}
200
201int	child;
202int	netf;
203char	line[MAXPATHLEN];
204int	confirmed;
205
206struct winsize win = { 0, 0, 0, 0 };
207
208
209void
210doit(f, fromp)
211	int f;
212	struct sockaddr_in *fromp;
213{
214	int master, pid, on = 1;
215	int authenticated = 0;
216	register struct hostent *hp;
217	char hostname[2 * MAXHOSTNAMELEN + 1];
218	char c;
219
220	alarm(60);
221	read(f, &c, 1);
222
223	if (c != 0)
224		exit(1);
225#ifdef	KERBEROS
226	if (vacuous)
227		fatal(f, "Remote host requires Kerberos authentication", 0);
228#endif
229
230	alarm(0);
231	fromp->sin_port = ntohs((u_short)fromp->sin_port);
232	hp = gethostbyaddr((char *)&fromp->sin_addr, sizeof(struct in_addr),
233	    fromp->sin_family);
234	if (hp) {
235		(void)strncpy(hostname, hp->h_name, sizeof(hostname));
236	} else {
237		(void)strncpy(hostname, inet_ntoa(fromp->sin_addr), sizeof(hostname));
238	}
239	hostname[sizeof(hostname) - 1] = '\0';
240
241#ifdef	KERBEROS
242	if (use_kerberos) {
243		retval = do_krb_login(fromp);
244		if (retval == 0)
245			authenticated++;
246		else if (retval > 0)
247			fatal(f, krb_err_txt[retval], 0);
248		write(f, &c, 1);
249		confirmed = 1;		/* we sent the null! */
250	} else
251#endif
252	{
253		if (fromp->sin_family != AF_INET ||
254		    fromp->sin_port >= IPPORT_RESERVED ||
255		    fromp->sin_port < IPPORT_RESERVED/2) {
256			syslog(LOG_NOTICE, "Connection from %s on illegal port",
257				inet_ntoa(fromp->sin_addr));
258			fatal(f, "Permission denied", 0);
259		}
260#ifdef IP_OPTIONS
261		{
262		u_char optbuf[BUFSIZ/3];
263		int optsize = sizeof(optbuf), ipproto, i;
264		struct protoent *ip;
265
266		if ((ip = getprotobyname("ip")) != NULL)
267			ipproto = ip->p_proto;
268		else
269			ipproto = IPPROTO_IP;
270		if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
271		    &optsize) == 0 && optsize != 0) {
272			for (i = 0; i < optsize; ) {
273				u_char c = optbuf[i];
274				if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
275					syslog(LOG_NOTICE,
276						"Connection refused from %s with IP option %s",
277						inet_ntoa(fromp->sin_addr),
278						c == IPOPT_LSRR ? "LSRR" : "SSRR");
279					exit(1);
280				}
281				if (c == IPOPT_EOL)
282					break;
283				i += (c == IPOPT_NOP) ? 1 : optbuf[i+1];
284			}
285		}
286		}
287#endif
288		if (do_rlogin(fromp) == 0)
289			authenticated++;
290	}
291	if (confirmed == 0) {
292		write(f, "", 1);
293		confirmed = 1;		/* we sent the null! */
294	}
295#ifdef	KERBEROS
296#ifdef	CRYPT
297	if (doencrypt)
298		(void) des_enc_write(f,
299				     SECURE_MESSAGE,
300				     strlen(SECURE_MESSAGE),
301				     schedule, &kdata->session);
302#endif
303#endif
304	netf = f;
305
306	pid = forkpty(&master, line, NULL, &win);
307	if (pid < 0) {
308		if (errno == ENOENT)
309			fatal(f, "Out of ptys", 0);
310		else
311			fatal(f, "Forkpty", 1);
312	}
313	if (pid == 0) {
314		if (f > 2)	/* f should always be 0, but... */
315			(void) close(f);
316		setup_term(0);
317		 if (*lusername=='-') {
318			syslog(LOG_ERR, "tried to pass user \"%s\" to login",
319			       lusername);
320			fatal(STDERR_FILENO, "invalid user", 0);
321		}
322		if (authenticated) {
323#ifdef	KERBEROS
324			if (use_kerberos && (pwd->pw_uid == 0))
325				syslog(LOG_INFO|LOG_AUTH,
326				    "ROOT Kerberos login from %s.%s@%s on %s\n",
327				    kdata->pname, kdata->pinst, kdata->prealm,
328				    hostname);
329#endif
330
331			execl(_PATH_LOGIN, "login", "-p",
332			    "-h", hostname, "-f", lusername, (char *)NULL);
333		} else
334			execl(_PATH_LOGIN, "login", "-p",
335			    "-h", hostname, lusername, (char *)NULL);
336		fatal(STDERR_FILENO, _PATH_LOGIN, 1);
337		/*NOTREACHED*/
338	}
339#ifdef	CRYPT
340#ifdef	KERBEROS
341	/*
342	 * If encrypted, don't turn on NBIO or the des read/write
343	 * routines will croak.
344	 */
345
346	if (!doencrypt)
347#endif
348#endif
349		ioctl(f, FIONBIO, &on);
350	ioctl(master, FIONBIO, &on);
351	ioctl(master, TIOCPKT, &on);
352	signal(SIGCHLD, cleanup);
353	protocol(f, master);
354	signal(SIGCHLD, SIG_IGN);
355	cleanup(0);
356}
357
358char	magic[2] = { 0377, 0377 };
359char	oobdata[] = {TIOCPKT_WINDOW};
360
361/*
362 * Handle a "control" request (signaled by magic being present)
363 * in the data stream.  For now, we are only willing to handle
364 * window size changes.
365 */
366int
367control(pty, cp, n)
368	int pty;
369	char *cp;
370	int n;
371{
372	struct winsize w;
373
374	if (n < 4+sizeof (w) || cp[2] != 's' || cp[3] != 's')
375		return (0);
376	oobdata[0] &= ~TIOCPKT_WINDOW;	/* we know he heard */
377	bcopy(cp+4, (char *)&w, sizeof(w));
378	w.ws_row = ntohs(w.ws_row);
379	w.ws_col = ntohs(w.ws_col);
380	w.ws_xpixel = ntohs(w.ws_xpixel);
381	w.ws_ypixel = ntohs(w.ws_ypixel);
382	(void)ioctl(pty, TIOCSWINSZ, &w);
383	return (4+sizeof (w));
384}
385
386/*
387 * rlogin "protocol" machine.
388 */
389void
390protocol(f, p)
391	register int f, p;
392{
393	char pibuf[1024+1], fibuf[1024], *pbp, *fbp;
394	register pcc = 0, fcc = 0;
395	int cc, nfd, n;
396	char cntl;
397
398	/*
399	 * Must ignore SIGTTOU, otherwise we'll stop
400	 * when we try and set slave pty's window shape
401	 * (our controlling tty is the master pty).
402	 */
403	(void) signal(SIGTTOU, SIG_IGN);
404	send(f, oobdata, 1, MSG_OOB);	/* indicate new rlogin */
405	if (f > p)
406		nfd = f + 1;
407	else
408		nfd = p + 1;
409	if (nfd > FD_SETSIZE) {
410		syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
411		fatal(f, "internal error (select mask too small)", 0);
412	}
413	for (;;) {
414		fd_set ibits, obits, ebits, *omask;
415
416		FD_ZERO(&ebits);
417		FD_ZERO(&ibits);
418		FD_ZERO(&obits);
419		omask = (fd_set *)NULL;
420		if (fcc) {
421			FD_SET(p, &obits);
422			omask = &obits;
423		} else
424			FD_SET(f, &ibits);
425		if (pcc >= 0)
426			if (pcc) {
427				FD_SET(f, &obits);
428				omask = &obits;
429			} else
430				FD_SET(p, &ibits);
431		FD_SET(p, &ebits);
432		if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
433			if (errno == EINTR)
434				continue;
435			fatal(f, "select", 1);
436		}
437		if (n == 0) {
438			/* shouldn't happen... */
439			sleep(5);
440			continue;
441		}
442#define	pkcontrol(c)	((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
443		if (FD_ISSET(p, &ebits)) {
444			cc = read(p, &cntl, 1);
445			if (cc == 1 && pkcontrol(cntl)) {
446				cntl |= oobdata[0];
447				send(f, &cntl, 1, MSG_OOB);
448				if (cntl & TIOCPKT_FLUSHWRITE) {
449					pcc = 0;
450					FD_CLR(p, &ibits);
451				}
452			}
453		}
454		if (FD_ISSET(f, &ibits)) {
455#ifdef	CRYPT
456#ifdef	KERBEROS
457			if (doencrypt)
458				fcc = des_enc_read(f, fibuf, sizeof(fibuf),
459					schedule, &kdata->session);
460			else
461#endif
462#endif
463				fcc = read(f, fibuf, sizeof(fibuf));
464			if (fcc < 0 && errno == EWOULDBLOCK)
465				fcc = 0;
466			else {
467				register char *cp;
468				int left, n;
469
470				if (fcc <= 0)
471					break;
472				fbp = fibuf;
473
474			top:
475				for (cp = fibuf; cp < fibuf+fcc-1; cp++)
476					if (cp[0] == magic[0] &&
477					    cp[1] == magic[1]) {
478						left = fcc - (cp-fibuf);
479						n = control(p, cp, left);
480						if (n) {
481							left -= n;
482							if (left > 0)
483								bcopy(cp+n, cp, left);
484							fcc -= n;
485							goto top; /* n^2 */
486						}
487					}
488				FD_SET(p, &obits);		/* try write */
489			}
490		}
491
492		if (FD_ISSET(p, &obits) && fcc > 0) {
493			cc = write(p, fbp, fcc);
494			if (cc > 0) {
495				fcc -= cc;
496				fbp += cc;
497			}
498		}
499
500		if (FD_ISSET(p, &ibits)) {
501			pcc = read(p, pibuf, sizeof (pibuf));
502			pbp = pibuf;
503			if (pcc < 0 && errno == EWOULDBLOCK)
504				pcc = 0;
505			else if (pcc <= 0)
506				break;
507			else if (pibuf[0] == 0) {
508				pbp++, pcc--;
509#ifdef	CRYPT
510#ifdef	KERBEROS
511				if (!doencrypt)
512#endif
513#endif
514					FD_SET(f, &obits);	/* try write */
515			} else {
516				if (pkcontrol(pibuf[0])) {
517					pibuf[0] |= oobdata[0];
518					send(f, &pibuf[0], 1, MSG_OOB);
519				}
520				pcc = 0;
521			}
522		}
523		if ((FD_ISSET(f, &obits)) && pcc > 0) {
524#ifdef	CRYPT
525#ifdef	KERBEROS
526			if (doencrypt)
527				cc = des_enc_write(f, pbp, pcc,
528					schedule, &kdata->session);
529			else
530#endif
531#endif
532				cc = write(f, pbp, pcc);
533			if (cc < 0 && errno == EWOULDBLOCK) {
534				/*
535				 * This happens when we try write after read
536				 * from p, but some old kernels balk at large
537				 * writes even when select returns true.
538				 */
539				if (!FD_ISSET(p, &ibits))
540					sleep(5);
541				continue;
542			}
543			if (cc > 0) {
544				pcc -= cc;
545				pbp += cc;
546			}
547		}
548	}
549}
550
551void
552cleanup(signo)
553	int signo;
554{
555	char *p;
556
557	p = line + sizeof(_PATH_DEV) - 1;
558	if (logout(p))
559		logwtmp(p, "", "");
560	(void)chmod(line, 0666);
561	(void)chown(line, 0, 0);
562	*p = 'p';
563	(void)chmod(line, 0666);
564	(void)chown(line, 0, 0);
565	shutdown(netf, 2);
566	exit(1);
567}
568
569void
570fatal(f, msg, syserr)
571	int f;
572	char *msg;
573	int syserr;
574{
575	int len;
576	char buf[BUFSIZ], *bp = buf;
577
578	/*
579	 * Prepend binary one to message if we haven't sent
580	 * the magic null as confirmation.
581	 */
582	if (!confirmed)
583		*bp++ = '\01';		/* error indicator */
584	if (syserr)
585		len = sprintf(bp, "rlogind: %s: %s.\r\n",
586		    msg, strerror(errno));
587	else
588		len = sprintf(bp, "rlogind: %s.\r\n", msg);
589	(void) write(f, buf, bp + len - buf);
590	exit(1);
591}
592
593int
594do_rlogin(dest)
595	struct sockaddr_in *dest;
596{
597	getstr(rusername, sizeof(rusername), "remuser too long");
598	getstr(lusername, sizeof(lusername), "locuser too long");
599	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
600
601	pwd = getpwnam(lusername);
602	if (pwd == NULL)
603		return (-1);
604	/* XXX why don't we syslog() failure? */
605	return (iruserok(dest->sin_addr.s_addr, pwd->pw_uid == 0,
606		rusername, lusername));
607}
608
609void
610getstr(buf, cnt, errmsg)
611	char *buf;
612	int cnt;
613	char *errmsg;
614{
615	char c;
616
617	do {
618		if (read(0, &c, 1) != 1)
619			exit(1);
620		if (--cnt < 0)
621			fatal(STDOUT_FILENO, errmsg, 0);
622		*buf++ = c;
623	} while (c != 0);
624}
625
626extern	char **environ;
627
628void
629setup_term(fd)
630	int fd;
631{
632	register char *cp = index(term+ENVSIZE, '/');
633	char *speed;
634	struct termios tt;
635
636#ifndef notyet
637	tcgetattr(fd, &tt);
638	if (cp) {
639		*cp++ = '\0';
640		speed = cp;
641		cp = index(speed, '/');
642		if (cp)
643			*cp++ = '\0';
644		cfsetspeed(&tt, atoi(speed));
645	}
646
647	tt.c_iflag = TTYDEF_IFLAG;
648	tt.c_oflag = TTYDEF_OFLAG;
649	tt.c_lflag = TTYDEF_LFLAG;
650	tcsetattr(fd, TCSAFLUSH, &tt);
651#else
652	if (cp) {
653		*cp++ = '\0';
654		speed = cp;
655		cp = index(speed, '/');
656		if (cp)
657			*cp++ = '\0';
658		tcgetattr(fd, &tt);
659		cfsetspeed(&tt, atoi(speed));
660		tcsetattr(fd, TCSAFLUSH, &tt);
661	}
662#endif
663
664	env[0] = term;
665	env[1] = 0;
666	environ = env;
667}
668
669#ifdef	KERBEROS
670#define	VERSION_SIZE	9
671
672/*
673 * Do the remote kerberos login to the named host with the
674 * given inet address
675 *
676 * Return 0 on valid authorization
677 * Return -1 on valid authentication, no authorization
678 * Return >0 for error conditions
679 */
680int
681do_krb_login(dest)
682	struct sockaddr_in *dest;
683{
684	int rc;
685	char instance[INST_SZ], version[VERSION_SIZE];
686	long authopts = 0L;	/* !mutual */
687	struct sockaddr_in faddr;
688
689	kdata = (AUTH_DAT *) auth_buf;
690	ticket = (KTEXT) tick_buf;
691
692	instance[0] = '*';
693	instance[1] = '\0';
694
695#ifdef	CRYPT
696	if (doencrypt) {
697		rc = sizeof(faddr);
698		if (getsockname(0, (struct sockaddr *)&faddr, &rc))
699			return (-1);
700		authopts = KOPT_DO_MUTUAL;
701		rc = krb_recvauth(
702			authopts, 0,
703			ticket, "rcmd",
704			instance, dest, &faddr,
705			kdata, "", schedule, version);
706		 des_set_key(&kdata->session, schedule);
707
708	} else
709#endif
710		rc = krb_recvauth(
711			authopts, 0,
712			ticket, "rcmd",
713			instance, dest, (struct sockaddr_in *) 0,
714			kdata, "", NULL, version);
715
716	if (rc != KSUCCESS)
717		return (rc);
718
719	getstr(lusername, sizeof(lusername), "locuser");
720	/* get the "cmd" in the rcmd protocol */
721	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type");
722
723	pwd = getpwnam(lusername);
724	if (pwd == NULL)
725		return (-1);
726
727	/* returns nonzero for no access */
728	if (kuserok(kdata, lusername) != 0)
729		return (-1);
730
731	return (0);
732
733}
734#endif /* KERBEROS */
735
736void
737usage()
738{
739#ifdef KERBEROS
740	syslog(LOG_ERR, "usage: rlogind [-Daln] [-k | -v]");
741#else
742	syslog(LOG_ERR, "usage: rlogind [-Daln]");
743#endif
744}
745
746/*
747 * Check whether host h is in our local domain,
748 * defined as sharing the last two components of the domain part,
749 * or the entire domain part if the local domain has only one component.
750 * If either name is unqualified (contains no '.'),
751 * assume that the host is local, as it will be
752 * interpreted as such.
753 */
754int
755local_domain(h)
756	char *h;
757{
758	char localhost[MAXHOSTNAMELEN];
759	char *p1, *p2;
760
761	localhost[0] = 0;
762	(void) gethostname(localhost, sizeof(localhost));
763	p1 = topdomain(localhost);
764	p2 = topdomain(h);
765	if (p1 == NULL || p2 == NULL || !strcasecmp(p1, p2))
766		return (1);
767	return (0);
768}
769
770char *
771topdomain(h)
772	char *h;
773{
774	register char *p;
775	char *maybe = NULL;
776	int dots = 0;
777
778	for (p = h + strlen(h); p >= h; p--) {
779		if (*p == '.') {
780			if (++dots == 2)
781				return (p);
782			maybe = p;
783		}
784	}
785	return (maybe);
786}
787