xref: /freebsd/lib/libc/net/rcmd.c (revision 262e143bd46171a6415a5b28af260a5efa2a3db8)
1 /*
2  * Copyright (c) 1983, 1993, 1994
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 #if defined(LIBC_SCCS) && !defined(lint)
35 static char sccsid[] = "@(#)rcmd.c	8.3 (Berkeley) 3/26/94";
36 #endif /* LIBC_SCCS and not lint */
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
39 
40 #include "namespace.h"
41 #include <sys/param.h>
42 #include <sys/socket.h>
43 #include <sys/stat.h>
44 
45 #include <netinet/in.h>
46 #include <arpa/inet.h>
47 
48 #include <signal.h>
49 #include <fcntl.h>
50 #include <netdb.h>
51 #include <stdlib.h>
52 #include <unistd.h>
53 #include <pwd.h>
54 #include <errno.h>
55 #include <stdio.h>
56 #include <ctype.h>
57 #include <string.h>
58 #include <rpc/rpc.h>
59 #ifdef YP
60 #include <rpcsvc/yp_prot.h>
61 #include <rpcsvc/ypclnt.h>
62 #endif
63 #include <arpa/nameser.h>
64 #include "un-namespace.h"
65 
66 extern int innetgr( const char *, const char *, const char *, const char * );
67 
68 #define max(a, b)	((a > b) ? a : b)
69 
70 int __ivaliduser(FILE *, u_int32_t, const char *, const char *);
71 int __ivaliduser_af(FILE *,const void *, const char *, const char *, int, int);
72 int __ivaliduser_sa(FILE *, const struct sockaddr *, socklen_t, const char *,
73     const char *);
74 static int __icheckhost(const struct sockaddr *, socklen_t, const char *);
75 
76 char paddr[NI_MAXHOST];
77 
78 int
79 rcmd(ahost, rport, locuser, remuser, cmd, fd2p)
80 	char **ahost;
81 	u_short rport;
82 	const char *locuser, *remuser, *cmd;
83 	int *fd2p;
84 {
85 	return rcmd_af(ahost, rport, locuser, remuser, cmd, fd2p, AF_INET);
86 }
87 
88 int
89 rcmd_af(ahost, rport, locuser, remuser, cmd, fd2p, af)
90 	char **ahost;
91 	u_short rport;
92 	const char *locuser, *remuser, *cmd;
93 	int *fd2p;
94 	int af;
95 {
96 	struct addrinfo hints, *res, *ai;
97 	struct sockaddr_storage from;
98 	fd_set reads;
99 	sigset_t oldmask, newmask;
100 	pid_t pid;
101 	int s, aport, lport, timo, error;
102 	char c, *p;
103 	int refused, nres;
104 	char num[8];
105 	static char canonnamebuf[MAXDNAME];	/* is it proper here? */
106 
107 	/* call rcmdsh() with specified remote shell if appropriate. */
108 	if (!issetugid() && (p = getenv("RSH"))) {
109 		struct servent *sp = getservbyname("shell", "tcp");
110 
111 		if (sp && sp->s_port == rport)
112 			return (rcmdsh(ahost, rport, locuser, remuser,
113 			    cmd, p));
114 	}
115 
116 	/* use rsh(1) if non-root and remote port is shell. */
117 	if (geteuid()) {
118 		struct servent *sp = getservbyname("shell", "tcp");
119 
120 		if (sp && sp->s_port == rport)
121 			return (rcmdsh(ahost, rport, locuser, remuser,
122 			    cmd, NULL));
123 	}
124 
125 	pid = getpid();
126 
127 	memset(&hints, 0, sizeof(hints));
128 	hints.ai_flags = AI_CANONNAME;
129 	hints.ai_family = af;
130 	hints.ai_socktype = SOCK_STREAM;
131 	hints.ai_protocol = 0;
132 	(void)snprintf(num, sizeof(num), "%d", ntohs(rport));
133 	error = getaddrinfo(*ahost, num, &hints, &res);
134 	if (error) {
135 		fprintf(stderr, "rcmd: getaddrinfo: %s\n",
136 			gai_strerror(error));
137 		if (error == EAI_SYSTEM)
138 			fprintf(stderr, "rcmd: getaddrinfo: %s\n",
139 				strerror(errno));
140 		return (-1);
141 	}
142 
143 	if (res->ai_canonname
144 	 && strlen(res->ai_canonname) + 1 < sizeof(canonnamebuf)) {
145 		strncpy(canonnamebuf, res->ai_canonname, sizeof(canonnamebuf));
146 		*ahost = canonnamebuf;
147 	}
148 	nres = 0;
149 	for (ai = res; ai; ai = ai->ai_next)
150 		nres++;
151 	ai = res;
152 	refused = 0;
153 	sigemptyset(&newmask);
154 	sigaddset(&newmask, SIGURG);
155 	_sigprocmask(SIG_BLOCK, (const sigset_t *)&newmask, &oldmask);
156 	for (timo = 1, lport = IPPORT_RESERVED - 1;;) {
157 		s = rresvport_af(&lport, ai->ai_family);
158 		if (s < 0) {
159 			if (errno != EAGAIN && ai->ai_next) {
160 				ai = ai->ai_next;
161 				continue;
162 			}
163 			if (errno == EAGAIN)
164 				(void)fprintf(stderr,
165 				    "rcmd: socket: All ports in use\n");
166 			else
167 				(void)fprintf(stderr, "rcmd: socket: %s\n",
168 				    strerror(errno));
169 			freeaddrinfo(res);
170 			_sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask,
171 			    NULL);
172 			return (-1);
173 		}
174 		_fcntl(s, F_SETOWN, pid);
175 		if (_connect(s, ai->ai_addr, ai->ai_addrlen) >= 0)
176 			break;
177 		(void)_close(s);
178 		if (errno == EADDRINUSE) {
179 			lport--;
180 			continue;
181 		}
182 		if (errno == ECONNREFUSED)
183 			refused = 1;
184 		if (ai->ai_next == NULL && (!refused || timo > 16)) {
185 			(void)fprintf(stderr, "%s: %s\n",
186 				      *ahost, strerror(errno));
187 			freeaddrinfo(res);
188 			_sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask,
189 			    NULL);
190 			return (-1);
191 		}
192 		if (nres > 1) {
193 			int oerrno = errno;
194 
195 			getnameinfo(ai->ai_addr, ai->ai_addrlen, paddr,
196 			    sizeof(paddr), NULL, 0, NI_NUMERICHOST);
197 			(void)fprintf(stderr, "connect to address %s: ",
198 				      paddr);
199 			errno = oerrno;
200 			perror(0);
201 		}
202 		if ((ai = ai->ai_next) == NULL) {
203 			/* refused && timo <= 16 */
204 			struct timespec time_to_sleep, time_remaining;
205 
206 			time_to_sleep.tv_sec = timo;
207 			time_to_sleep.tv_nsec = 0;
208 			(void)_nanosleep(&time_to_sleep, &time_remaining);
209 			timo *= 2;
210 			ai = res;
211 			refused = 0;
212 		}
213 		if (nres > 1) {
214 			getnameinfo(ai->ai_addr, ai->ai_addrlen, paddr,
215 			    sizeof(paddr), NULL, 0, NI_NUMERICHOST);
216 			fprintf(stderr, "Trying %s...\n", paddr);
217 		}
218 	}
219 	lport--;
220 	if (fd2p == 0) {
221 		_write(s, "", 1);
222 		lport = 0;
223 	} else {
224 		int s2 = rresvport_af(&lport, ai->ai_family), s3;
225 		socklen_t len = ai->ai_addrlen;
226 		int nfds;
227 
228 		if (s2 < 0)
229 			goto bad;
230 		_listen(s2, 1);
231 		(void)snprintf(num, sizeof(num), "%d", lport);
232 		if (_write(s, num, strlen(num)+1) != strlen(num)+1) {
233 			(void)fprintf(stderr,
234 			    "rcmd: write (setting up stderr): %s\n",
235 			    strerror(errno));
236 			(void)_close(s2);
237 			goto bad;
238 		}
239 		nfds = max(s, s2)+1;
240 		if(nfds > FD_SETSIZE) {
241 			fprintf(stderr, "rcmd: too many files\n");
242 			(void)_close(s2);
243 			goto bad;
244 		}
245 again:
246 		FD_ZERO(&reads);
247 		FD_SET(s, &reads);
248 		FD_SET(s2, &reads);
249 		errno = 0;
250 		if (_select(nfds, &reads, 0, 0, 0) < 1 || !FD_ISSET(s2, &reads)){
251 			if (errno != 0)
252 				(void)fprintf(stderr,
253 				    "rcmd: select (setting up stderr): %s\n",
254 				    strerror(errno));
255 			else
256 				(void)fprintf(stderr,
257 				"select: protocol failure in circuit setup\n");
258 			(void)_close(s2);
259 			goto bad;
260 		}
261 		s3 = _accept(s2, (struct sockaddr *)&from, &len);
262 		switch (from.ss_family) {
263 		case AF_INET:
264 			aport = ntohs(((struct sockaddr_in *)&from)->sin_port);
265 			break;
266 #ifdef INET6
267 		case AF_INET6:
268 			aport = ntohs(((struct sockaddr_in6 *)&from)->sin6_port);
269 			break;
270 #endif
271 		default:
272 			aport = 0;	/* error */
273 			break;
274 		}
275 		/*
276 		 * XXX careful for ftp bounce attacks. If discovered, shut them
277 		 * down and check for the real auxiliary channel to connect.
278 		 */
279 		if (aport == 20) {
280 			_close(s3);
281 			goto again;
282 		}
283 		(void)_close(s2);
284 		if (s3 < 0) {
285 			(void)fprintf(stderr,
286 			    "rcmd: accept: %s\n", strerror(errno));
287 			lport = 0;
288 			goto bad;
289 		}
290 		*fd2p = s3;
291 		if (aport >= IPPORT_RESERVED || aport < IPPORT_RESERVED / 2) {
292 			(void)fprintf(stderr,
293 			    "socket: protocol failure in circuit setup.\n");
294 			goto bad2;
295 		}
296 	}
297 	(void)_write(s, locuser, strlen(locuser)+1);
298 	(void)_write(s, remuser, strlen(remuser)+1);
299 	(void)_write(s, cmd, strlen(cmd)+1);
300 	if (_read(s, &c, 1) != 1) {
301 		(void)fprintf(stderr,
302 		    "rcmd: %s: %s\n", *ahost, strerror(errno));
303 		goto bad2;
304 	}
305 	if (c != 0) {
306 		while (_read(s, &c, 1) == 1) {
307 			(void)_write(STDERR_FILENO, &c, 1);
308 			if (c == '\n')
309 				break;
310 		}
311 		goto bad2;
312 	}
313 	_sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask, NULL);
314 	freeaddrinfo(res);
315 	return (s);
316 bad2:
317 	if (lport)
318 		(void)_close(*fd2p);
319 bad:
320 	(void)_close(s);
321 	_sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask, NULL);
322 	freeaddrinfo(res);
323 	return (-1);
324 }
325 
326 int
327 rresvport(port)
328 	int *port;
329 {
330 	return rresvport_af(port, AF_INET);
331 }
332 
333 int
334 rresvport_af(alport, family)
335 	int *alport, family;
336 {
337 	int s;
338 	struct sockaddr_storage ss;
339 	u_short *sport;
340 
341 	memset(&ss, 0, sizeof(ss));
342 	ss.ss_family = family;
343 	switch (family) {
344 	case AF_INET:
345 		((struct sockaddr *)&ss)->sa_len = sizeof(struct sockaddr_in);
346 		sport = &((struct sockaddr_in *)&ss)->sin_port;
347 		((struct sockaddr_in *)&ss)->sin_addr.s_addr = INADDR_ANY;
348 		break;
349 #ifdef INET6
350 	case AF_INET6:
351 		((struct sockaddr *)&ss)->sa_len = sizeof(struct sockaddr_in6);
352 		sport = &((struct sockaddr_in6 *)&ss)->sin6_port;
353 		((struct sockaddr_in6 *)&ss)->sin6_addr = in6addr_any;
354 		break;
355 #endif
356 	default:
357 		errno = EAFNOSUPPORT;
358 		return -1;
359 	}
360 
361 	s = _socket(ss.ss_family, SOCK_STREAM, 0);
362 	if (s < 0)
363 		return (-1);
364 #if 0 /* compat_exact_traditional_rresvport_semantics */
365 	sin.sin_port = htons((u_short)*alport);
366 	if (_bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
367 		return (s);
368 	if (errno != EADDRINUSE) {
369 		(void)_close(s);
370 		return (-1);
371 	}
372 #endif
373 	*sport = 0;
374 	if (bindresvport_sa(s, (struct sockaddr *)&ss) == -1) {
375 		(void)_close(s);
376 		return (-1);
377 	}
378 	*alport = (int)ntohs(*sport);
379 	return (s);
380 }
381 
382 int	__check_rhosts_file = 1;
383 char	*__rcmd_errstr;
384 
385 int
386 ruserok(rhost, superuser, ruser, luser)
387 	const char *rhost, *ruser, *luser;
388 	int superuser;
389 {
390 	struct addrinfo hints, *res, *r;
391 	int error;
392 
393 	memset(&hints, 0, sizeof(hints));
394 	hints.ai_family = PF_UNSPEC;
395 	hints.ai_socktype = SOCK_DGRAM;	/*dummy*/
396 	error = getaddrinfo(rhost, "0", &hints, &res);
397 	if (error)
398 		return (-1);
399 
400 	for (r = res; r; r = r->ai_next) {
401 		if (iruserok_sa(r->ai_addr, r->ai_addrlen, superuser, ruser,
402 		    luser) == 0) {
403 			freeaddrinfo(res);
404 			return (0);
405 		}
406 	}
407 	freeaddrinfo(res);
408 	return (-1);
409 }
410 
411 /*
412  * New .rhosts strategy: We are passed an ip address. We spin through
413  * hosts.equiv and .rhosts looking for a match. When the .rhosts only
414  * has ip addresses, we don't have to trust a nameserver.  When it
415  * contains hostnames, we spin through the list of addresses the nameserver
416  * gives us and look for a match.
417  *
418  * Returns 0 if ok, -1 if not ok.
419  */
420 int
421 iruserok(raddr, superuser, ruser, luser)
422 	unsigned long raddr;
423 	int superuser;
424 	const char *ruser, *luser;
425 {
426 	struct sockaddr_in sin;
427 
428 	memset(&sin, 0, sizeof(sin));
429 	sin.sin_family = AF_INET;
430 	sin.sin_len = sizeof(struct sockaddr_in);
431 	memcpy(&sin.sin_addr, &raddr, sizeof(sin.sin_addr));
432 	return iruserok_sa((struct sockaddr *)&sin, sin.sin_len, superuser,
433 		ruser, luser);
434 }
435 
436 /*
437  * AF independent extension of iruserok.
438  *
439  * Returns 0 if ok, -1 if not ok.
440  */
441 int
442 iruserok_sa(ra, rlen, superuser, ruser, luser)
443 	const void *ra;
444 	int rlen;
445 	int superuser;
446 	const char *ruser, *luser;
447 {
448 	char *cp;
449 	struct stat sbuf;
450 	struct passwd *pwd;
451 	FILE *hostf;
452 	uid_t uid;
453 	int first;
454 	char pbuf[MAXPATHLEN];
455 	const struct sockaddr *raddr;
456 	struct sockaddr_storage ss;
457 
458 	/* avoid alignment issue */
459 	if (rlen > sizeof(ss))
460 		return(-1);
461 	memcpy(&ss, ra, rlen);
462 	raddr = (struct sockaddr *)&ss;
463 
464 	first = 1;
465 	hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r");
466 again:
467 	if (hostf) {
468 		if (__ivaliduser_sa(hostf, raddr, rlen, luser, ruser) == 0) {
469 			(void)fclose(hostf);
470 			return (0);
471 		}
472 		(void)fclose(hostf);
473 	}
474 	if (first == 1 && (__check_rhosts_file || superuser)) {
475 		first = 0;
476 		if ((pwd = getpwnam(luser)) == NULL)
477 			return (-1);
478 		(void)strcpy(pbuf, pwd->pw_dir);
479 		(void)strcat(pbuf, "/.rhosts");
480 
481 		/*
482 		 * Change effective uid while opening .rhosts.  If root and
483 		 * reading an NFS mounted file system, can't read files that
484 		 * are protected read/write owner only.
485 		 */
486 		uid = geteuid();
487 		(void)seteuid(pwd->pw_uid);
488 		hostf = fopen(pbuf, "r");
489 		(void)seteuid(uid);
490 
491 		if (hostf == NULL)
492 			return (-1);
493 		/*
494 		 * If not a regular file, or is owned by someone other than
495 		 * user or root or if writeable by anyone but the owner, quit.
496 		 */
497 		cp = NULL;
498 		if (lstat(pbuf, &sbuf) < 0)
499 			cp = ".rhosts lstat failed";
500 		else if (!S_ISREG(sbuf.st_mode))
501 			cp = ".rhosts not regular file";
502 		else if (_fstat(fileno(hostf), &sbuf) < 0)
503 			cp = ".rhosts fstat failed";
504 		else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid)
505 			cp = "bad .rhosts owner";
506 		else if (sbuf.st_mode & (S_IWGRP|S_IWOTH))
507 			cp = ".rhosts writeable by other than owner";
508 		/* If there were any problems, quit. */
509 		if (cp) {
510 			__rcmd_errstr = cp;
511 			(void)fclose(hostf);
512 			return (-1);
513 		}
514 		goto again;
515 	}
516 	return (-1);
517 }
518 
519 /*
520  * XXX
521  * Don't make static, used by lpd(8).
522  *
523  * Returns 0 if ok, -1 if not ok.
524  */
525 int
526 __ivaliduser(hostf, raddr, luser, ruser)
527 	FILE *hostf;
528 	u_int32_t raddr;
529 	const char *luser, *ruser;
530 {
531 	struct sockaddr_in sin;
532 
533 	memset(&sin, 0, sizeof(sin));
534 	sin.sin_family = AF_INET;
535 	sin.sin_len = sizeof(struct sockaddr_in);
536 	memcpy(&sin.sin_addr, &raddr, sizeof(sin.sin_addr));
537 	return __ivaliduser_sa(hostf, (struct sockaddr *)&sin, sin.sin_len,
538 		luser, ruser);
539 }
540 
541 /*
542  * Returns 0 if ok, -1 if not ok.
543  *
544  * XXX obsolete API.
545  */
546 int
547 __ivaliduser_af(hostf, raddr, luser, ruser, af, len)
548 	FILE *hostf;
549 	const void *raddr;
550 	const char *luser, *ruser;
551 	int af, len;
552 {
553 	struct sockaddr *sa = NULL;
554 	struct sockaddr_in *sin = NULL;
555 #ifdef INET6
556 	struct sockaddr_in6 *sin6 = NULL;
557 #endif
558 	struct sockaddr_storage ss;
559 
560 	memset(&ss, 0, sizeof(ss));
561 	switch (af) {
562 	case AF_INET:
563 		if (len != sizeof(sin->sin_addr))
564 			return -1;
565 		sin = (struct sockaddr_in *)&ss;
566 		sin->sin_family = AF_INET;
567 		sin->sin_len = sizeof(struct sockaddr_in);
568 		memcpy(&sin->sin_addr, raddr, sizeof(sin->sin_addr));
569 		break;
570 #ifdef INET6
571 	case AF_INET6:
572 		if (len != sizeof(sin6->sin6_addr))
573 			return -1;
574 		/* you will lose scope info */
575 		sin6 = (struct sockaddr_in6 *)&ss;
576 		sin6->sin6_family = AF_INET6;
577 		sin6->sin6_len = sizeof(struct sockaddr_in6);
578 		memcpy(&sin6->sin6_addr, raddr, sizeof(sin6->sin6_addr));
579 		break;
580 #endif
581 	default:
582 		return -1;
583 	}
584 
585 	sa = (struct sockaddr *)&ss;
586 	return __ivaliduser_sa(hostf, sa, sa->sa_len, luser, ruser);
587 }
588 
589 int
590 __ivaliduser_sa(hostf, raddr, salen, luser, ruser)
591 	FILE *hostf;
592 	const struct sockaddr *raddr;
593 	socklen_t salen;
594 	const char *luser, *ruser;
595 {
596 	char *user, *p;
597 	int ch;
598 	char buf[MAXHOSTNAMELEN + 128];		/* host + login */
599 	char hname[MAXHOSTNAMELEN];
600 	/* Presumed guilty until proven innocent. */
601 	int userok = 0, hostok = 0;
602 #ifdef YP
603 	char *ypdomain;
604 
605 	if (yp_get_default_domain(&ypdomain))
606 		ypdomain = NULL;
607 #else
608 #define	ypdomain NULL
609 #endif
610 	/* We need to get the damn hostname back for netgroup matching. */
611 	if (getnameinfo(raddr, salen, hname, sizeof(hname), NULL, 0,
612 			NI_NAMEREQD) != 0)
613 		hname[0] = '\0';
614 
615 	while (fgets(buf, sizeof(buf), hostf)) {
616 		p = buf;
617 		/* Skip lines that are too long. */
618 		if (strchr(p, '\n') == NULL) {
619 			while ((ch = getc(hostf)) != '\n' && ch != EOF);
620 			continue;
621 		}
622 		if (*p == '\n' || *p == '#') {
623 			/* comment... */
624 			continue;
625 		}
626 		while (*p != '\n' && *p != ' ' && *p != '\t' && *p != '\0') {
627 			*p = isupper((unsigned char)*p) ? tolower((unsigned char)*p) : *p;
628 			p++;
629 		}
630 		if (*p == ' ' || *p == '\t') {
631 			*p++ = '\0';
632 			while (*p == ' ' || *p == '\t')
633 				p++;
634 			user = p;
635 			while (*p != '\n' && *p != ' ' &&
636 			    *p != '\t' && *p != '\0')
637 				p++;
638 		} else
639 			user = p;
640 		*p = '\0';
641 		/*
642 		 * Do +/- and +@/-@ checking. This looks really nasty,
643 		 * but it matches SunOS's behavior so far as I can tell.
644 		 */
645 		switch(buf[0]) {
646 		case '+':
647 			if (!buf[1]) {     /* '+' matches all hosts */
648 				hostok = 1;
649 				break;
650 			}
651 			if (buf[1] == '@')  /* match a host by netgroup */
652 				hostok = hname[0] != '\0' &&
653 				    innetgr(&buf[2], hname, NULL, ypdomain);
654 			else		/* match a host by addr */
655 				hostok = __icheckhost(raddr, salen,
656 						      (char *)&buf[1]);
657 			break;
658 		case '-':     /* reject '-' hosts and all their users */
659 			if (buf[1] == '@') {
660 				if (hname[0] == '\0' ||
661 				    innetgr(&buf[2], hname, NULL, ypdomain))
662 					return(-1);
663 			} else {
664 				if (__icheckhost(raddr, salen,
665 						 (char *)&buf[1]))
666 					return(-1);
667 			}
668 			break;
669 		default:  /* if no '+' or '-', do a simple match */
670 			hostok = __icheckhost(raddr, salen, buf);
671 			break;
672 		}
673 		switch(*user) {
674 		case '+':
675 			if (!*(user+1)) {      /* '+' matches all users */
676 				userok = 1;
677 				break;
678 			}
679 			if (*(user+1) == '@')  /* match a user by netgroup */
680 				userok = innetgr(user+2, NULL, ruser, ypdomain);
681 			else	   /* match a user by direct specification */
682 				userok = !(strcmp(ruser, user+1));
683 			break;
684 		case '-': 		/* if we matched a hostname, */
685 			if (hostok) {   /* check for user field rejections */
686 				if (!*(user+1))
687 					return(-1);
688 				if (*(user+1) == '@') {
689 					if (innetgr(user+2, NULL,
690 							ruser, ypdomain))
691 						return(-1);
692 				} else {
693 					if (!strcmp(ruser, user+1))
694 						return(-1);
695 				}
696 			}
697 			break;
698 		default:	/* no rejections: try to match the user */
699 			if (hostok)
700 				userok = !(strcmp(ruser,*user ? user : luser));
701 			break;
702 		}
703 		if (hostok && userok)
704 			return(0);
705 	}
706 	return (-1);
707 }
708 
709 /*
710  * Returns "true" if match, 0 if no match.
711  */
712 static int
713 __icheckhost(raddr, salen, lhost)
714 	const struct sockaddr *raddr;
715 	socklen_t salen;
716         const char *lhost;
717 {
718 	struct sockaddr_in sin;
719 	struct sockaddr_in6 *sin6;
720 	struct addrinfo hints, *res, *r;
721 	int error;
722 	char h1[NI_MAXHOST], h2[NI_MAXHOST];
723 
724 	if (raddr->sa_family == AF_INET6) {
725 		sin6 = (struct sockaddr_in6 *)raddr;
726 		if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) {
727 			memset(&sin, 0, sizeof(sin));
728 			sin.sin_family = AF_INET;
729 			sin.sin_len = sizeof(struct sockaddr_in);
730 			memcpy(&sin.sin_addr, &sin6->sin6_addr.s6_addr[12],
731 			       sizeof(sin.sin_addr));
732 			raddr = (struct sockaddr *)&sin;
733 			salen = sin.sin_len;
734 		}
735 	}
736 
737 	h1[0] = '\0';
738 	if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0,
739 			NI_NUMERICHOST) != 0)
740 		return (0);
741 
742 	/* Resolve laddr into sockaddr */
743 	memset(&hints, 0, sizeof(hints));
744 	hints.ai_family = raddr->sa_family;
745 	hints.ai_socktype = SOCK_DGRAM;	/*XXX dummy*/
746 	res = NULL;
747 	error = getaddrinfo(lhost, "0", &hints, &res);
748 	if (error)
749 		return (0);
750 
751 	for (r = res; r ; r = r->ai_next) {
752 		h2[0] = '\0';
753 		if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2),
754 				NULL, 0, NI_NUMERICHOST) != 0)
755 			continue;
756 		if (strcmp(h1, h2) == 0) {
757 			freeaddrinfo(res);
758 			return (1);
759 		}
760 	}
761 
762 	/* No match. */
763 	freeaddrinfo(res);
764 	return (0);
765 }
766