rlogind.c revision 21673 
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 *	$FreeBSD: head/libexec/rlogind/rlogind.c 21673 1997-01-14 07:20:47Z jkh $
34 */
35
36#ifndef lint
37static 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 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/param.h>
57#include <sys/stat.h>
58#include <sys/ioctl.h>
59#include <signal.h>
60#include <termios.h>
61
62#include <sys/socket.h>
63#include <netinet/in.h>
64#include <netinet/in_systm.h>
65#include <netinet/ip.h>
66#include <netinet/tcp.h>
67#include <arpa/inet.h>
68#include <netdb.h>
69
70#include <pwd.h>
71#include <syslog.h>
72#include <errno.h>
73#include <stdio.h>
74#include <unistd.h>
75#include <stdlib.h>
76#include <string.h>
77#include "pathnames.h"
78
79#ifndef TIOCPKT_WINDOW
80#define TIOCPKT_WINDOW 0x80
81#endif
82
83#ifdef	KERBEROS
84#include <des.h>
85#include <kerberosIV/krb.h>
86#define	SECURE_MESSAGE "This rlogin session is using DES encryption for all transmissions.\r\n"
87
88AUTH_DAT	*kdata;
89KTEXT		ticket;
90u_char		auth_buf[sizeof(AUTH_DAT)];
91u_char		tick_buf[sizeof(KTEXT_ST)];
92Key_schedule	schedule;
93int		doencrypt, retval, use_kerberos, vacuous;
94
95#define		ARGSTR			"Dalnkvx"
96#else
97#define		ARGSTR			"Daln"
98#endif	/* KERBEROS */
99
100char	*env[2];
101#define	NMAX 30
102char	lusername[NMAX+1], rusername[NMAX+1];
103static	char term[64] = "TERM=";
104#define	ENVSIZE	(sizeof("TERM=")-1)	/* skip null for concatenation */
105int	keepalive = 1;
106int	check_all = 0;
107int	no_delay;
108
109struct	passwd *pwd;
110
111void	doit __P((int, struct sockaddr_in *));
112int	control __P((int, char *, int));
113void	protocol __P((int, int));
114void	cleanup __P((int));
115void	fatal __P((int, char *, int));
116int	do_rlogin __P((struct sockaddr_in *));
117void	getstr __P((char *, int, char *));
118void	setup_term __P((int));
119int	do_krb_login __P((struct sockaddr_in *));
120void	usage __P((void));
121int	local_domain __P((char *));
122char	*topdomain __P((char *));
123
124int
125main(argc, argv)
126	int argc;
127	char *argv[];
128{
129	extern int __check_rhosts_file;
130	struct sockaddr_in from;
131	int ch, fromlen, on;
132
133	openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
134
135	opterr = 0;
136	while ((ch = getopt(argc, argv, ARGSTR)) != EOF)
137		switch (ch) {
138		case 'D':
139			no_delay = 1;
140			break;
141		case 'a':
142			check_all = 1;
143			break;
144		case 'l':
145			__check_rhosts_file = 0;
146			break;
147		case 'n':
148			keepalive = 0;
149			break;
150#ifdef KERBEROS
151		case 'k':
152			use_kerberos = 1;
153			break;
154		case 'v':
155			vacuous = 1;
156			break;
157#ifdef CRYPT
158		case 'x':
159			doencrypt = 1;
160			break;
161#endif
162#endif
163		case '?':
164		default:
165			usage();
166			break;
167		}
168	argc -= optind;
169	argv += optind;
170
171#ifdef	KERBEROS
172	if (use_kerberos && vacuous) {
173		usage();
174		fatal(STDERR_FILENO, "only one of -k and -v allowed", 0);
175	}
176#endif
177	fromlen = sizeof (from);
178	if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
179		syslog(LOG_ERR,"Can't get peer name of remote host: %m");
180		fatal(STDERR_FILENO, "Can't get peer name of remote host", 1);
181	}
182	on = 1;
183	if (keepalive &&
184	    setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0)
185		syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
186	if (no_delay &&
187	    setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
188		syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
189	on = IPTOS_LOWDELAY;
190	if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
191		syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
192
193	doit(0, &from);
194}
195
196int	child;
197int	netf;
198char	line[MAXPATHLEN];
199int	confirmed;
200
201struct winsize win = { 0, 0, 0, 0 };
202
203
204void
205doit(f, fromp)
206	int f;
207	struct sockaddr_in *fromp;
208{
209	int master, pid, on = 1;
210	int authenticated = 0;
211	register struct hostent *hp;
212	char hostname[2 * MAXHOSTNAMELEN + 1];
213	char c;
214
215	alarm(60);
216	read(f, &c, 1);
217
218	if (c != 0)
219		exit(1);
220#ifdef	KERBEROS
221	if (vacuous)
222		fatal(f, "Remote host requires Kerberos authentication", 0);
223#endif
224
225	alarm(0);
226	fromp->sin_port = ntohs((u_short)fromp->sin_port);
227	hp = gethostbyaddr((char *)&fromp->sin_addr, sizeof(struct in_addr),
228	    fromp->sin_family);
229	if (hp)
230		(void)strcpy(hostname, hp->h_name);
231	else
232		(void)strcpy(hostname, inet_ntoa(fromp->sin_addr));
233
234#ifdef	KERBEROS
235	if (use_kerberos) {
236		retval = do_krb_login(fromp);
237		if (retval == 0)
238			authenticated++;
239		else if (retval > 0)
240			fatal(f, krb_err_txt[retval], 0);
241		write(f, &c, 1);
242		confirmed = 1;		/* we sent the null! */
243	} else
244#endif
245	{
246		if (fromp->sin_family != AF_INET ||
247		    fromp->sin_port >= IPPORT_RESERVED ||
248		    fromp->sin_port < IPPORT_RESERVED/2) {
249			syslog(LOG_NOTICE, "Connection from %s on illegal port",
250				inet_ntoa(fromp->sin_addr));
251			fatal(f, "Permission denied", 0);
252		}
253#ifdef IP_OPTIONS
254		{
255		u_char optbuf[BUFSIZ/3], *cp;
256		char lbuf[BUFSIZ], *lp;
257		int optsize = sizeof(optbuf), ipproto;
258		struct protoent *ip;
259
260		if ((ip = getprotobyname("ip")) != NULL)
261			ipproto = ip->p_proto;
262		else
263			ipproto = IPPROTO_IP;
264		if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
265		    &optsize) == 0 && optsize != 0) {
266			lp = lbuf;
267			for (cp = optbuf; optsize > 0; cp++, optsize--, lp += 3)
268				sprintf(lp, " %2.2x", *cp);
269			syslog(LOG_NOTICE,
270			    "Connection received using IP options (ignored):%s",
271			    lbuf);
272			if (setsockopt(0, ipproto, IP_OPTIONS,
273			    (char *)NULL, optsize) != 0) {
274				syslog(LOG_ERR,
275				    "setsockopt IP_OPTIONS NULL: %m");
276				exit(1);
277			}
278		}
279		}
280#endif
281		if (do_rlogin(fromp) == 0)
282			authenticated++;
283	}
284	if (confirmed == 0) {
285		write(f, "", 1);
286		confirmed = 1;		/* we sent the null! */
287	}
288#ifdef	KERBEROS
289#ifdef	CRYPT
290	if (doencrypt)
291		(void) des_write(f, SECURE_MESSAGE, sizeof(SECURE_MESSAGE) - 1);
292#endif
293#endif
294	netf = f;
295
296	pid = forkpty(&master, line, NULL, &win);
297	if (pid < 0) {
298		if (errno == ENOENT)
299			fatal(f, "Out of ptys", 0);
300		else
301			fatal(f, "Forkpty", 1);
302	}
303	if (pid == 0) {
304		if (f > 2)	/* f should always be 0, but... */
305			(void) close(f);
306		setup_term(0);
307		 if (*lusername=='-') {
308			syslog(LOG_ERR, "tried to pass user \"%s\" to login",
309			       lusername);
310			fatal(STDERR_FILENO, "invalid user", 0);
311		}
312		if (authenticated) {
313#ifdef	KERBEROS
314			if (use_kerberos && (pwd->pw_uid == 0))
315				syslog(LOG_INFO|LOG_AUTH,
316				    "ROOT Kerberos login from %s.%s@%s on %s\n",
317				    kdata->pname, kdata->pinst, kdata->prealm,
318				    hostname);
319#endif
320
321			execl(_PATH_LOGIN, "login", "-p",
322			    "-h", hostname, "-f", lusername, (char *)NULL);
323		} else
324			execl(_PATH_LOGIN, "login", "-p",
325			    "-h", hostname, lusername, (char *)NULL);
326		fatal(STDERR_FILENO, _PATH_LOGIN, 1);
327		/*NOTREACHED*/
328	}
329#ifdef	CRYPT
330#ifdef	KERBEROS
331	/*
332	 * If encrypted, don't turn on NBIO or the des read/write
333	 * routines will croak.
334	 */
335
336	if (!doencrypt)
337#endif
338#endif
339		ioctl(f, FIONBIO, &on);
340	ioctl(master, FIONBIO, &on);
341	ioctl(master, TIOCPKT, &on);
342	signal(SIGCHLD, cleanup);
343	protocol(f, master);
344	signal(SIGCHLD, SIG_IGN);
345	cleanup(0);
346}
347
348char	magic[2] = { 0377, 0377 };
349char	oobdata[] = {TIOCPKT_WINDOW};
350
351/*
352 * Handle a "control" request (signaled by magic being present)
353 * in the data stream.  For now, we are only willing to handle
354 * window size changes.
355 */
356int
357control(pty, cp, n)
358	int pty;
359	char *cp;
360	int n;
361{
362	struct winsize w;
363
364	if (n < 4+sizeof (w) || cp[2] != 's' || cp[3] != 's')
365		return (0);
366	oobdata[0] &= ~TIOCPKT_WINDOW;	/* we know he heard */
367	bcopy(cp+4, (char *)&w, sizeof(w));
368	w.ws_row = ntohs(w.ws_row);
369	w.ws_col = ntohs(w.ws_col);
370	w.ws_xpixel = ntohs(w.ws_xpixel);
371	w.ws_ypixel = ntohs(w.ws_ypixel);
372	(void)ioctl(pty, TIOCSWINSZ, &w);
373	return (4+sizeof (w));
374}
375
376/*
377 * rlogin "protocol" machine.
378 */
379void
380protocol(f, p)
381	register int f, p;
382{
383	char pibuf[1024+1], fibuf[1024], *pbp, *fbp;
384	register pcc = 0, fcc = 0;
385	int cc, nfd, n;
386	char cntl;
387
388	/*
389	 * Must ignore SIGTTOU, otherwise we'll stop
390	 * when we try and set slave pty's window shape
391	 * (our controlling tty is the master pty).
392	 */
393	(void) signal(SIGTTOU, SIG_IGN);
394	send(f, oobdata, 1, MSG_OOB);	/* indicate new rlogin */
395	if (f > p)
396		nfd = f + 1;
397	else
398		nfd = p + 1;
399	if (nfd > FD_SETSIZE) {
400		syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
401		fatal(f, "internal error (select mask too small)", 0);
402	}
403	for (;;) {
404		fd_set ibits, obits, ebits, *omask;
405
406		FD_ZERO(&ebits);
407		FD_ZERO(&ibits);
408		FD_ZERO(&obits);
409		omask = (fd_set *)NULL;
410		if (fcc) {
411			FD_SET(p, &obits);
412			omask = &obits;
413		} else
414			FD_SET(f, &ibits);
415		if (pcc >= 0)
416			if (pcc) {
417				FD_SET(f, &obits);
418				omask = &obits;
419			} else
420				FD_SET(p, &ibits);
421		FD_SET(p, &ebits);
422		if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
423			if (errno == EINTR)
424				continue;
425			fatal(f, "select", 1);
426		}
427		if (n == 0) {
428			/* shouldn't happen... */
429			sleep(5);
430			continue;
431		}
432#define	pkcontrol(c)	((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
433		if (FD_ISSET(p, &ebits)) {
434			cc = read(p, &cntl, 1);
435			if (cc == 1 && pkcontrol(cntl)) {
436				cntl |= oobdata[0];
437				send(f, &cntl, 1, MSG_OOB);
438				if (cntl & TIOCPKT_FLUSHWRITE) {
439					pcc = 0;
440					FD_CLR(p, &ibits);
441				}
442			}
443		}
444		if (FD_ISSET(f, &ibits)) {
445#ifdef	CRYPT
446#ifdef	KERBEROS
447			if (doencrypt)
448				fcc = des_read(f, fibuf, sizeof(fibuf));
449			else
450#endif
451#endif
452				fcc = read(f, fibuf, sizeof(fibuf));
453			if (fcc < 0 && errno == EWOULDBLOCK)
454				fcc = 0;
455			else {
456				register char *cp;
457				int left, n;
458
459				if (fcc <= 0)
460					break;
461				fbp = fibuf;
462
463			top:
464				for (cp = fibuf; cp < fibuf+fcc-1; cp++)
465					if (cp[0] == magic[0] &&
466					    cp[1] == magic[1]) {
467						left = fcc - (cp-fibuf);
468						n = control(p, cp, left);
469						if (n) {
470							left -= n;
471							if (left > 0)
472								bcopy(cp+n, cp, left);
473							fcc -= n;
474							goto top; /* n^2 */
475						}
476					}
477				FD_SET(p, &obits);		/* try write */
478			}
479		}
480
481		if (FD_ISSET(p, &obits) && fcc > 0) {
482			cc = write(p, fbp, fcc);
483			if (cc > 0) {
484				fcc -= cc;
485				fbp += cc;
486			}
487		}
488
489		if (FD_ISSET(p, &ibits)) {
490			pcc = read(p, pibuf, sizeof (pibuf));
491			pbp = pibuf;
492			if (pcc < 0 && errno == EWOULDBLOCK)
493				pcc = 0;
494			else if (pcc <= 0)
495				break;
496			else if (pibuf[0] == 0) {
497				pbp++, pcc--;
498#ifdef	CRYPT
499#ifdef	KERBEROS
500				if (!doencrypt)
501#endif
502#endif
503					FD_SET(f, &obits);	/* try write */
504			} else {
505				if (pkcontrol(pibuf[0])) {
506					pibuf[0] |= oobdata[0];
507					send(f, &pibuf[0], 1, MSG_OOB);
508				}
509				pcc = 0;
510			}
511		}
512		if ((FD_ISSET(f, &obits)) && pcc > 0) {
513#ifdef	CRYPT
514#ifdef	KERBEROS
515			if (doencrypt)
516				cc = des_write(f, pbp, pcc);
517			else
518#endif
519#endif
520				cc = write(f, pbp, pcc);
521			if (cc < 0 && errno == EWOULDBLOCK) {
522				/*
523				 * This happens when we try write after read
524				 * from p, but some old kernels balk at large
525				 * writes even when select returns true.
526				 */
527				if (!FD_ISSET(p, &ibits))
528					sleep(5);
529				continue;
530			}
531			if (cc > 0) {
532				pcc -= cc;
533				pbp += cc;
534			}
535		}
536	}
537}
538
539void
540cleanup(signo)
541	int signo;
542{
543	char *p;
544
545	p = line + sizeof(_PATH_DEV) - 1;
546	if (logout(p))
547		logwtmp(p, "", "");
548	(void)chmod(line, 0666);
549	(void)chown(line, 0, 0);
550	*p = 'p';
551	(void)chmod(line, 0666);
552	(void)chown(line, 0, 0);
553	shutdown(netf, 2);
554	exit(1);
555}
556
557void
558fatal(f, msg, syserr)
559	int f;
560	char *msg;
561	int syserr;
562{
563	int len;
564	char buf[BUFSIZ], *bp = buf;
565
566	/*
567	 * Prepend binary one to message if we haven't sent
568	 * the magic null as confirmation.
569	 */
570	if (!confirmed)
571		*bp++ = '\01';		/* error indicator */
572	if (syserr)
573		len = sprintf(bp, "rlogind: %s: %s.\r\n",
574		    msg, strerror(errno));
575	else
576		len = sprintf(bp, "rlogind: %s.\r\n", msg);
577	(void) write(f, buf, bp + len - buf);
578	exit(1);
579}
580
581int
582do_rlogin(dest)
583	struct sockaddr_in *dest;
584{
585	getstr(rusername, sizeof(rusername), "remuser too long");
586	getstr(lusername, sizeof(lusername), "locuser too long");
587	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
588
589	pwd = getpwnam(lusername);
590	if (pwd == NULL)
591		return (-1);
592	/* XXX why don't we syslog() failure? */
593	return (iruserok(dest->sin_addr.s_addr, pwd->pw_uid == 0,
594		rusername, lusername));
595}
596
597void
598getstr(buf, cnt, errmsg)
599	char *buf;
600	int cnt;
601	char *errmsg;
602{
603	char c;
604
605	do {
606		if (read(0, &c, 1) != 1)
607			exit(1);
608		if (--cnt < 0)
609			fatal(STDOUT_FILENO, errmsg, 0);
610		*buf++ = c;
611	} while (c != 0);
612}
613
614extern	char **environ;
615
616void
617setup_term(fd)
618	int fd;
619{
620	register char *cp = index(term+ENVSIZE, '/');
621	char *speed;
622	struct termios tt;
623
624#ifndef notyet
625	tcgetattr(fd, &tt);
626	if (cp) {
627		*cp++ = '\0';
628		speed = cp;
629		cp = index(speed, '/');
630		if (cp)
631			*cp++ = '\0';
632		cfsetspeed(&tt, atoi(speed));
633	}
634
635	tt.c_iflag = TTYDEF_IFLAG;
636	tt.c_oflag = TTYDEF_OFLAG;
637	tt.c_lflag = TTYDEF_LFLAG;
638	tcsetattr(fd, TCSAFLUSH, &tt);
639#else
640	if (cp) {
641		*cp++ = '\0';
642		speed = cp;
643		cp = index(speed, '/');
644		if (cp)
645			*cp++ = '\0';
646		tcgetattr(fd, &tt);
647		cfsetspeed(&tt, atoi(speed));
648		tcsetattr(fd, TCSAFLUSH, &tt);
649	}
650#endif
651
652	env[0] = term;
653	env[1] = 0;
654	environ = env;
655}
656
657#ifdef	KERBEROS
658#define	VERSION_SIZE	9
659
660/*
661 * Do the remote kerberos login to the named host with the
662 * given inet address
663 *
664 * Return 0 on valid authorization
665 * Return -1 on valid authentication, no authorization
666 * Return >0 for error conditions
667 */
668int
669do_krb_login(dest)
670	struct sockaddr_in *dest;
671{
672	int rc;
673	char instance[INST_SZ], version[VERSION_SIZE];
674	long authopts = 0L;	/* !mutual */
675	struct sockaddr_in faddr;
676
677	kdata = (AUTH_DAT *) auth_buf;
678	ticket = (KTEXT) tick_buf;
679
680	instance[0] = '*';
681	instance[1] = '\0';
682
683#ifdef	CRYPT
684	if (doencrypt) {
685		rc = sizeof(faddr);
686		if (getsockname(0, (struct sockaddr *)&faddr, &rc))
687			return (-1);
688		authopts = KOPT_DO_MUTUAL;
689		rc = krb_recvauth(
690			authopts, 0,
691			ticket, "rcmd",
692			instance, dest, &faddr,
693			kdata, "", schedule, version);
694		 des_set_key_krb(&kdata->session, schedule);
695
696	} else
697#endif
698		rc = krb_recvauth(
699			authopts, 0,
700			ticket, "rcmd",
701			instance, dest, (struct sockaddr_in *) 0,
702			kdata, "", NULL, version);
703
704	if (rc != KSUCCESS)
705		return (rc);
706
707	getstr(lusername, sizeof(lusername), "locuser");
708	/* get the "cmd" in the rcmd protocol */
709	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type");
710
711	pwd = getpwnam(lusername);
712	if (pwd == NULL)
713		return (-1);
714
715	/* returns nonzero for no access */
716	if (kuserok(kdata, lusername) != 0)
717		return (-1);
718
719	return (0);
720
721}
722#endif /* KERBEROS */
723
724void
725usage()
726{
727#ifdef KERBEROS
728	syslog(LOG_ERR, "usage: rlogind [-Daln] [-k | -v]");
729#else
730	syslog(LOG_ERR, "usage: rlogind [-Daln]");
731#endif
732}
733
734/*
735 * Check whether host h is in our local domain,
736 * defined as sharing the last two components of the domain part,
737 * or the entire domain part if the local domain has only one component.
738 * If either name is unqualified (contains no '.'),
739 * assume that the host is local, as it will be
740 * interpreted as such.
741 */
742int
743local_domain(h)
744	char *h;
745{
746	char localhost[MAXHOSTNAMELEN];
747	char *p1, *p2;
748
749	localhost[0] = 0;
750	(void) gethostname(localhost, sizeof(localhost));
751	p1 = topdomain(localhost);
752	p2 = topdomain(h);
753	if (p1 == NULL || p2 == NULL || !strcasecmp(p1, p2))
754		return (1);
755	return (0);
756}
757
758char *
759topdomain(h)
760	char *h;
761{
762	register char *p;
763	char *maybe = NULL;
764	int dots = 0;
765
766	for (p = h + strlen(h); p >= h; p--) {
767		if (*p == '.') {
768			if (++dots == 2)
769				return (p);
770			maybe = p;
771		}
772	}
773	return (maybe);
774}
775