xref: /freebsd/lib/libc/net/rcmd.c (revision f0a75d274af375d15b97b830966b99a02b7db911)
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  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #if defined(LIBC_SCCS) && !defined(lint)
31 static char sccsid[] = "@(#)rcmd.c	8.3 (Berkeley) 3/26/94";
32 #endif /* LIBC_SCCS and not lint */
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35 
36 #include "namespace.h"
37 #include <sys/param.h>
38 #include <sys/socket.h>
39 #include <sys/stat.h>
40 
41 #include <netinet/in.h>
42 #include <arpa/inet.h>
43 
44 #include <signal.h>
45 #include <fcntl.h>
46 #include <netdb.h>
47 #include <stdlib.h>
48 #include <unistd.h>
49 #include <pwd.h>
50 #include <errno.h>
51 #include <stdio.h>
52 #include <ctype.h>
53 #include <string.h>
54 #include <rpc/rpc.h>
55 #ifdef YP
56 #include <rpcsvc/yp_prot.h>
57 #include <rpcsvc/ypclnt.h>
58 #endif
59 #include <arpa/nameser.h>
60 #include "un-namespace.h"
61 
62 extern int innetgr( const char *, const char *, const char *, const char * );
63 
64 #define max(a, b)	((a > b) ? a : b)
65 
66 int __ivaliduser(FILE *, u_int32_t, const char *, const char *);
67 int __ivaliduser_af(FILE *,const void *, const char *, const char *, int, int);
68 int __ivaliduser_sa(FILE *, const struct sockaddr *, socklen_t, const char *,
69     const char *);
70 static int __icheckhost(const struct sockaddr *, socklen_t, const char *);
71 
72 char paddr[NI_MAXHOST];
73 
74 int
75 rcmd(ahost, rport, locuser, remuser, cmd, fd2p)
76 	char **ahost;
77 	u_short rport;
78 	const char *locuser, *remuser, *cmd;
79 	int *fd2p;
80 {
81 	return rcmd_af(ahost, rport, locuser, remuser, cmd, fd2p, AF_INET);
82 }
83 
84 int
85 rcmd_af(ahost, rport, locuser, remuser, cmd, fd2p, af)
86 	char **ahost;
87 	u_short rport;
88 	const char *locuser, *remuser, *cmd;
89 	int *fd2p;
90 	int af;
91 {
92 	struct addrinfo hints, *res, *ai;
93 	struct sockaddr_storage from;
94 	fd_set reads;
95 	sigset_t oldmask, newmask;
96 	pid_t pid;
97 	int s, aport, lport, timo, error;
98 	char c, *p;
99 	int refused, nres;
100 	char num[8];
101 	static char canonnamebuf[MAXDNAME];	/* is it proper here? */
102 
103 	/* call rcmdsh() with specified remote shell if appropriate. */
104 	if (!issetugid() && (p = getenv("RSH"))) {
105 		struct servent *sp = getservbyname("shell", "tcp");
106 
107 		if (sp && sp->s_port == rport)
108 			return (rcmdsh(ahost, rport, locuser, remuser,
109 			    cmd, p));
110 	}
111 
112 	/* use rsh(1) if non-root and remote port is shell. */
113 	if (geteuid()) {
114 		struct servent *sp = getservbyname("shell", "tcp");
115 
116 		if (sp && sp->s_port == rport)
117 			return (rcmdsh(ahost, rport, locuser, remuser,
118 			    cmd, NULL));
119 	}
120 
121 	pid = getpid();
122 
123 	memset(&hints, 0, sizeof(hints));
124 	hints.ai_flags = AI_CANONNAME;
125 	hints.ai_family = af;
126 	hints.ai_socktype = SOCK_STREAM;
127 	hints.ai_protocol = 0;
128 	(void)snprintf(num, sizeof(num), "%d", ntohs(rport));
129 	error = getaddrinfo(*ahost, num, &hints, &res);
130 	if (error) {
131 		fprintf(stderr, "rcmd: getaddrinfo: %s\n",
132 			gai_strerror(error));
133 		if (error == EAI_SYSTEM)
134 			fprintf(stderr, "rcmd: getaddrinfo: %s\n",
135 				strerror(errno));
136 		return (-1);
137 	}
138 
139 	if (res->ai_canonname
140 	 && strlen(res->ai_canonname) + 1 < sizeof(canonnamebuf)) {
141 		strncpy(canonnamebuf, res->ai_canonname, sizeof(canonnamebuf));
142 		*ahost = canonnamebuf;
143 	}
144 	nres = 0;
145 	for (ai = res; ai; ai = ai->ai_next)
146 		nres++;
147 	ai = res;
148 	refused = 0;
149 	sigemptyset(&newmask);
150 	sigaddset(&newmask, SIGURG);
151 	_sigprocmask(SIG_BLOCK, (const sigset_t *)&newmask, &oldmask);
152 	for (timo = 1, lport = IPPORT_RESERVED - 1;;) {
153 		s = rresvport_af(&lport, ai->ai_family);
154 		if (s < 0) {
155 			if (errno != EAGAIN && ai->ai_next) {
156 				ai = ai->ai_next;
157 				continue;
158 			}
159 			if (errno == EAGAIN)
160 				(void)fprintf(stderr,
161 				    "rcmd: socket: All ports in use\n");
162 			else
163 				(void)fprintf(stderr, "rcmd: socket: %s\n",
164 				    strerror(errno));
165 			freeaddrinfo(res);
166 			_sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask,
167 			    NULL);
168 			return (-1);
169 		}
170 		_fcntl(s, F_SETOWN, pid);
171 		if (_connect(s, ai->ai_addr, ai->ai_addrlen) >= 0)
172 			break;
173 		(void)_close(s);
174 		if (errno == EADDRINUSE) {
175 			lport--;
176 			continue;
177 		}
178 		if (errno == ECONNREFUSED)
179 			refused = 1;
180 		if (ai->ai_next == NULL && (!refused || timo > 16)) {
181 			(void)fprintf(stderr, "%s: %s\n",
182 				      *ahost, strerror(errno));
183 			freeaddrinfo(res);
184 			_sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask,
185 			    NULL);
186 			return (-1);
187 		}
188 		if (nres > 1) {
189 			int oerrno = errno;
190 
191 			getnameinfo(ai->ai_addr, ai->ai_addrlen, paddr,
192 			    sizeof(paddr), NULL, 0, NI_NUMERICHOST);
193 			(void)fprintf(stderr, "connect to address %s: ",
194 				      paddr);
195 			errno = oerrno;
196 			perror(0);
197 		}
198 		if ((ai = ai->ai_next) == NULL) {
199 			/* refused && timo <= 16 */
200 			struct timespec time_to_sleep, time_remaining;
201 
202 			time_to_sleep.tv_sec = timo;
203 			time_to_sleep.tv_nsec = 0;
204 			(void)_nanosleep(&time_to_sleep, &time_remaining);
205 			timo *= 2;
206 			ai = res;
207 			refused = 0;
208 		}
209 		if (nres > 1) {
210 			getnameinfo(ai->ai_addr, ai->ai_addrlen, paddr,
211 			    sizeof(paddr), NULL, 0, NI_NUMERICHOST);
212 			fprintf(stderr, "Trying %s...\n", paddr);
213 		}
214 	}
215 	lport--;
216 	if (fd2p == 0) {
217 		_write(s, "", 1);
218 		lport = 0;
219 	} else {
220 		int s2 = rresvport_af(&lport, ai->ai_family), s3;
221 		socklen_t len = ai->ai_addrlen;
222 		int nfds;
223 
224 		if (s2 < 0)
225 			goto bad;
226 		_listen(s2, 1);
227 		(void)snprintf(num, sizeof(num), "%d", lport);
228 		if (_write(s, num, strlen(num)+1) != strlen(num)+1) {
229 			(void)fprintf(stderr,
230 			    "rcmd: write (setting up stderr): %s\n",
231 			    strerror(errno));
232 			(void)_close(s2);
233 			goto bad;
234 		}
235 		nfds = max(s, s2)+1;
236 		if(nfds > FD_SETSIZE) {
237 			fprintf(stderr, "rcmd: too many files\n");
238 			(void)_close(s2);
239 			goto bad;
240 		}
241 again:
242 		FD_ZERO(&reads);
243 		FD_SET(s, &reads);
244 		FD_SET(s2, &reads);
245 		errno = 0;
246 		if (_select(nfds, &reads, 0, 0, 0) < 1 || !FD_ISSET(s2, &reads)){
247 			if (errno != 0)
248 				(void)fprintf(stderr,
249 				    "rcmd: select (setting up stderr): %s\n",
250 				    strerror(errno));
251 			else
252 				(void)fprintf(stderr,
253 				"select: protocol failure in circuit setup\n");
254 			(void)_close(s2);
255 			goto bad;
256 		}
257 		s3 = _accept(s2, (struct sockaddr *)&from, &len);
258 		switch (from.ss_family) {
259 		case AF_INET:
260 			aport = ntohs(((struct sockaddr_in *)&from)->sin_port);
261 			break;
262 #ifdef INET6
263 		case AF_INET6:
264 			aport = ntohs(((struct sockaddr_in6 *)&from)->sin6_port);
265 			break;
266 #endif
267 		default:
268 			aport = 0;	/* error */
269 			break;
270 		}
271 		/*
272 		 * XXX careful for ftp bounce attacks. If discovered, shut them
273 		 * down and check for the real auxiliary channel to connect.
274 		 */
275 		if (aport == 20) {
276 			_close(s3);
277 			goto again;
278 		}
279 		(void)_close(s2);
280 		if (s3 < 0) {
281 			(void)fprintf(stderr,
282 			    "rcmd: accept: %s\n", strerror(errno));
283 			lport = 0;
284 			goto bad;
285 		}
286 		*fd2p = s3;
287 		if (aport >= IPPORT_RESERVED || aport < IPPORT_RESERVED / 2) {
288 			(void)fprintf(stderr,
289 			    "socket: protocol failure in circuit setup.\n");
290 			goto bad2;
291 		}
292 	}
293 	(void)_write(s, locuser, strlen(locuser)+1);
294 	(void)_write(s, remuser, strlen(remuser)+1);
295 	(void)_write(s, cmd, strlen(cmd)+1);
296 	if (_read(s, &c, 1) != 1) {
297 		(void)fprintf(stderr,
298 		    "rcmd: %s: %s\n", *ahost, strerror(errno));
299 		goto bad2;
300 	}
301 	if (c != 0) {
302 		while (_read(s, &c, 1) == 1) {
303 			(void)_write(STDERR_FILENO, &c, 1);
304 			if (c == '\n')
305 				break;
306 		}
307 		goto bad2;
308 	}
309 	_sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask, NULL);
310 	freeaddrinfo(res);
311 	return (s);
312 bad2:
313 	if (lport)
314 		(void)_close(*fd2p);
315 bad:
316 	(void)_close(s);
317 	_sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask, NULL);
318 	freeaddrinfo(res);
319 	return (-1);
320 }
321 
322 int
323 rresvport(port)
324 	int *port;
325 {
326 	return rresvport_af(port, AF_INET);
327 }
328 
329 int
330 rresvport_af(alport, family)
331 	int *alport, family;
332 {
333 	int s;
334 	struct sockaddr_storage ss;
335 	u_short *sport;
336 
337 	memset(&ss, 0, sizeof(ss));
338 	ss.ss_family = family;
339 	switch (family) {
340 	case AF_INET:
341 		((struct sockaddr *)&ss)->sa_len = sizeof(struct sockaddr_in);
342 		sport = &((struct sockaddr_in *)&ss)->sin_port;
343 		((struct sockaddr_in *)&ss)->sin_addr.s_addr = INADDR_ANY;
344 		break;
345 #ifdef INET6
346 	case AF_INET6:
347 		((struct sockaddr *)&ss)->sa_len = sizeof(struct sockaddr_in6);
348 		sport = &((struct sockaddr_in6 *)&ss)->sin6_port;
349 		((struct sockaddr_in6 *)&ss)->sin6_addr = in6addr_any;
350 		break;
351 #endif
352 	default:
353 		errno = EAFNOSUPPORT;
354 		return -1;
355 	}
356 
357 	s = _socket(ss.ss_family, SOCK_STREAM, 0);
358 	if (s < 0)
359 		return (-1);
360 #if 0 /* compat_exact_traditional_rresvport_semantics */
361 	sin.sin_port = htons((u_short)*alport);
362 	if (_bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
363 		return (s);
364 	if (errno != EADDRINUSE) {
365 		(void)_close(s);
366 		return (-1);
367 	}
368 #endif
369 	*sport = 0;
370 	if (bindresvport_sa(s, (struct sockaddr *)&ss) == -1) {
371 		(void)_close(s);
372 		return (-1);
373 	}
374 	*alport = (int)ntohs(*sport);
375 	return (s);
376 }
377 
378 int	__check_rhosts_file = 1;
379 char	*__rcmd_errstr;
380 
381 int
382 ruserok(rhost, superuser, ruser, luser)
383 	const char *rhost, *ruser, *luser;
384 	int superuser;
385 {
386 	struct addrinfo hints, *res, *r;
387 	int error;
388 
389 	memset(&hints, 0, sizeof(hints));
390 	hints.ai_family = PF_UNSPEC;
391 	hints.ai_socktype = SOCK_DGRAM;	/*dummy*/
392 	error = getaddrinfo(rhost, "0", &hints, &res);
393 	if (error)
394 		return (-1);
395 
396 	for (r = res; r; r = r->ai_next) {
397 		if (iruserok_sa(r->ai_addr, r->ai_addrlen, superuser, ruser,
398 		    luser) == 0) {
399 			freeaddrinfo(res);
400 			return (0);
401 		}
402 	}
403 	freeaddrinfo(res);
404 	return (-1);
405 }
406 
407 /*
408  * New .rhosts strategy: We are passed an ip address. We spin through
409  * hosts.equiv and .rhosts looking for a match. When the .rhosts only
410  * has ip addresses, we don't have to trust a nameserver.  When it
411  * contains hostnames, we spin through the list of addresses the nameserver
412  * gives us and look for a match.
413  *
414  * Returns 0 if ok, -1 if not ok.
415  */
416 int
417 iruserok(raddr, superuser, ruser, luser)
418 	unsigned long raddr;
419 	int superuser;
420 	const char *ruser, *luser;
421 {
422 	struct sockaddr_in sin;
423 
424 	memset(&sin, 0, sizeof(sin));
425 	sin.sin_family = AF_INET;
426 	sin.sin_len = sizeof(struct sockaddr_in);
427 	memcpy(&sin.sin_addr, &raddr, sizeof(sin.sin_addr));
428 	return iruserok_sa((struct sockaddr *)&sin, sin.sin_len, superuser,
429 		ruser, luser);
430 }
431 
432 /*
433  * AF independent extension of iruserok.
434  *
435  * Returns 0 if ok, -1 if not ok.
436  */
437 int
438 iruserok_sa(ra, rlen, superuser, ruser, luser)
439 	const void *ra;
440 	int rlen;
441 	int superuser;
442 	const char *ruser, *luser;
443 {
444 	char *cp;
445 	struct stat sbuf;
446 	struct passwd *pwd;
447 	FILE *hostf;
448 	uid_t uid;
449 	int first;
450 	char pbuf[MAXPATHLEN];
451 	const struct sockaddr *raddr;
452 	struct sockaddr_storage ss;
453 
454 	/* avoid alignment issue */
455 	if (rlen > sizeof(ss))
456 		return(-1);
457 	memcpy(&ss, ra, rlen);
458 	raddr = (struct sockaddr *)&ss;
459 
460 	first = 1;
461 	hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r");
462 again:
463 	if (hostf) {
464 		if (__ivaliduser_sa(hostf, raddr, rlen, luser, ruser) == 0) {
465 			(void)fclose(hostf);
466 			return (0);
467 		}
468 		(void)fclose(hostf);
469 	}
470 	if (first == 1 && (__check_rhosts_file || superuser)) {
471 		first = 0;
472 		if ((pwd = getpwnam(luser)) == NULL)
473 			return (-1);
474 		(void)strcpy(pbuf, pwd->pw_dir);
475 		(void)strcat(pbuf, "/.rhosts");
476 
477 		/*
478 		 * Change effective uid while opening .rhosts.  If root and
479 		 * reading an NFS mounted file system, can't read files that
480 		 * are protected read/write owner only.
481 		 */
482 		uid = geteuid();
483 		(void)seteuid(pwd->pw_uid);
484 		hostf = fopen(pbuf, "r");
485 		(void)seteuid(uid);
486 
487 		if (hostf == NULL)
488 			return (-1);
489 		/*
490 		 * If not a regular file, or is owned by someone other than
491 		 * user or root or if writeable by anyone but the owner, quit.
492 		 */
493 		cp = NULL;
494 		if (lstat(pbuf, &sbuf) < 0)
495 			cp = ".rhosts lstat failed";
496 		else if (!S_ISREG(sbuf.st_mode))
497 			cp = ".rhosts not regular file";
498 		else if (_fstat(fileno(hostf), &sbuf) < 0)
499 			cp = ".rhosts fstat failed";
500 		else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid)
501 			cp = "bad .rhosts owner";
502 		else if (sbuf.st_mode & (S_IWGRP|S_IWOTH))
503 			cp = ".rhosts writeable by other than owner";
504 		/* If there were any problems, quit. */
505 		if (cp) {
506 			__rcmd_errstr = cp;
507 			(void)fclose(hostf);
508 			return (-1);
509 		}
510 		goto again;
511 	}
512 	return (-1);
513 }
514 
515 /*
516  * XXX
517  * Don't make static, used by lpd(8).
518  *
519  * Returns 0 if ok, -1 if not ok.
520  */
521 int
522 __ivaliduser(hostf, raddr, luser, ruser)
523 	FILE *hostf;
524 	u_int32_t raddr;
525 	const char *luser, *ruser;
526 {
527 	struct sockaddr_in sin;
528 
529 	memset(&sin, 0, sizeof(sin));
530 	sin.sin_family = AF_INET;
531 	sin.sin_len = sizeof(struct sockaddr_in);
532 	memcpy(&sin.sin_addr, &raddr, sizeof(sin.sin_addr));
533 	return __ivaliduser_sa(hostf, (struct sockaddr *)&sin, sin.sin_len,
534 		luser, ruser);
535 }
536 
537 /*
538  * Returns 0 if ok, -1 if not ok.
539  *
540  * XXX obsolete API.
541  */
542 int
543 __ivaliduser_af(hostf, raddr, luser, ruser, af, len)
544 	FILE *hostf;
545 	const void *raddr;
546 	const char *luser, *ruser;
547 	int af, len;
548 {
549 	struct sockaddr *sa = NULL;
550 	struct sockaddr_in *sin = NULL;
551 #ifdef INET6
552 	struct sockaddr_in6 *sin6 = NULL;
553 #endif
554 	struct sockaddr_storage ss;
555 
556 	memset(&ss, 0, sizeof(ss));
557 	switch (af) {
558 	case AF_INET:
559 		if (len != sizeof(sin->sin_addr))
560 			return -1;
561 		sin = (struct sockaddr_in *)&ss;
562 		sin->sin_family = AF_INET;
563 		sin->sin_len = sizeof(struct sockaddr_in);
564 		memcpy(&sin->sin_addr, raddr, sizeof(sin->sin_addr));
565 		break;
566 #ifdef INET6
567 	case AF_INET6:
568 		if (len != sizeof(sin6->sin6_addr))
569 			return -1;
570 		/* you will lose scope info */
571 		sin6 = (struct sockaddr_in6 *)&ss;
572 		sin6->sin6_family = AF_INET6;
573 		sin6->sin6_len = sizeof(struct sockaddr_in6);
574 		memcpy(&sin6->sin6_addr, raddr, sizeof(sin6->sin6_addr));
575 		break;
576 #endif
577 	default:
578 		return -1;
579 	}
580 
581 	sa = (struct sockaddr *)&ss;
582 	return __ivaliduser_sa(hostf, sa, sa->sa_len, luser, ruser);
583 }
584 
585 int
586 __ivaliduser_sa(hostf, raddr, salen, luser, ruser)
587 	FILE *hostf;
588 	const struct sockaddr *raddr;
589 	socklen_t salen;
590 	const char *luser, *ruser;
591 {
592 	char *user, *p;
593 	int ch;
594 	char buf[MAXHOSTNAMELEN + 128];		/* host + login */
595 	char hname[MAXHOSTNAMELEN];
596 	/* Presumed guilty until proven innocent. */
597 	int userok = 0, hostok = 0;
598 #ifdef YP
599 	char *ypdomain;
600 
601 	if (yp_get_default_domain(&ypdomain))
602 		ypdomain = NULL;
603 #else
604 #define	ypdomain NULL
605 #endif
606 	/* We need to get the damn hostname back for netgroup matching. */
607 	if (getnameinfo(raddr, salen, hname, sizeof(hname), NULL, 0,
608 			NI_NAMEREQD) != 0)
609 		hname[0] = '\0';
610 
611 	while (fgets(buf, sizeof(buf), hostf)) {
612 		p = buf;
613 		/* Skip lines that are too long. */
614 		if (strchr(p, '\n') == NULL) {
615 			while ((ch = getc(hostf)) != '\n' && ch != EOF);
616 			continue;
617 		}
618 		if (*p == '\n' || *p == '#') {
619 			/* comment... */
620 			continue;
621 		}
622 		while (*p != '\n' && *p != ' ' && *p != '\t' && *p != '\0') {
623 			*p = isupper((unsigned char)*p) ? tolower((unsigned char)*p) : *p;
624 			p++;
625 		}
626 		if (*p == ' ' || *p == '\t') {
627 			*p++ = '\0';
628 			while (*p == ' ' || *p == '\t')
629 				p++;
630 			user = p;
631 			while (*p != '\n' && *p != ' ' &&
632 			    *p != '\t' && *p != '\0')
633 				p++;
634 		} else
635 			user = p;
636 		*p = '\0';
637 		/*
638 		 * Do +/- and +@/-@ checking. This looks really nasty,
639 		 * but it matches SunOS's behavior so far as I can tell.
640 		 */
641 		switch(buf[0]) {
642 		case '+':
643 			if (!buf[1]) {     /* '+' matches all hosts */
644 				hostok = 1;
645 				break;
646 			}
647 			if (buf[1] == '@')  /* match a host by netgroup */
648 				hostok = hname[0] != '\0' &&
649 				    innetgr(&buf[2], hname, NULL, ypdomain);
650 			else		/* match a host by addr */
651 				hostok = __icheckhost(raddr, salen,
652 						      (char *)&buf[1]);
653 			break;
654 		case '-':     /* reject '-' hosts and all their users */
655 			if (buf[1] == '@') {
656 				if (hname[0] == '\0' ||
657 				    innetgr(&buf[2], hname, NULL, ypdomain))
658 					return(-1);
659 			} else {
660 				if (__icheckhost(raddr, salen,
661 						 (char *)&buf[1]))
662 					return(-1);
663 			}
664 			break;
665 		default:  /* if no '+' or '-', do a simple match */
666 			hostok = __icheckhost(raddr, salen, buf);
667 			break;
668 		}
669 		switch(*user) {
670 		case '+':
671 			if (!*(user+1)) {      /* '+' matches all users */
672 				userok = 1;
673 				break;
674 			}
675 			if (*(user+1) == '@')  /* match a user by netgroup */
676 				userok = innetgr(user+2, NULL, ruser, ypdomain);
677 			else	   /* match a user by direct specification */
678 				userok = !(strcmp(ruser, user+1));
679 			break;
680 		case '-': 		/* if we matched a hostname, */
681 			if (hostok) {   /* check for user field rejections */
682 				if (!*(user+1))
683 					return(-1);
684 				if (*(user+1) == '@') {
685 					if (innetgr(user+2, NULL,
686 							ruser, ypdomain))
687 						return(-1);
688 				} else {
689 					if (!strcmp(ruser, user+1))
690 						return(-1);
691 				}
692 			}
693 			break;
694 		default:	/* no rejections: try to match the user */
695 			if (hostok)
696 				userok = !(strcmp(ruser,*user ? user : luser));
697 			break;
698 		}
699 		if (hostok && userok)
700 			return(0);
701 	}
702 	return (-1);
703 }
704 
705 /*
706  * Returns "true" if match, 0 if no match.
707  */
708 static int
709 __icheckhost(raddr, salen, lhost)
710 	const struct sockaddr *raddr;
711 	socklen_t salen;
712         const char *lhost;
713 {
714 	struct sockaddr_in sin;
715 	struct sockaddr_in6 *sin6;
716 	struct addrinfo hints, *res, *r;
717 	int error;
718 	char h1[NI_MAXHOST], h2[NI_MAXHOST];
719 
720 	if (raddr->sa_family == AF_INET6) {
721 		sin6 = (struct sockaddr_in6 *)raddr;
722 		if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) {
723 			memset(&sin, 0, sizeof(sin));
724 			sin.sin_family = AF_INET;
725 			sin.sin_len = sizeof(struct sockaddr_in);
726 			memcpy(&sin.sin_addr, &sin6->sin6_addr.s6_addr[12],
727 			       sizeof(sin.sin_addr));
728 			raddr = (struct sockaddr *)&sin;
729 			salen = sin.sin_len;
730 		}
731 	}
732 
733 	h1[0] = '\0';
734 	if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0,
735 			NI_NUMERICHOST) != 0)
736 		return (0);
737 
738 	/* Resolve laddr into sockaddr */
739 	memset(&hints, 0, sizeof(hints));
740 	hints.ai_family = raddr->sa_family;
741 	hints.ai_socktype = SOCK_DGRAM;	/*XXX dummy*/
742 	res = NULL;
743 	error = getaddrinfo(lhost, "0", &hints, &res);
744 	if (error)
745 		return (0);
746 
747 	for (r = res; r ; r = r->ai_next) {
748 		h2[0] = '\0';
749 		if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2),
750 				NULL, 0, NI_NUMERICHOST) != 0)
751 			continue;
752 		if (strcmp(h1, h2) == 0) {
753 			freeaddrinfo(res);
754 			return (1);
755 		}
756 	}
757 
758 	/* No match. */
759 	freeaddrinfo(res);
760 	return (0);
761 }
762