xref: /illumos-gate/usr/src/lib/nsswitch/files/common/getnetgrent.c (revision 20a7641f9918de8574b8b3b47dbe35c4bfc78df1)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2012 Nexenta Systems, Inc.  All rights reserved.
23  *
24  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
25  * Use is subject to license terms.
26  */
27 
28 /*
29  *	files/getnetgrent.c -- "files" backend for nsswitch "netgroup" database
30  *
31  *	The API for netgroups differs sufficiently from that for the average
32  *	getXXXbyYYY function that we use very few of the support routines in
33  *	files_common.h.
34  *
35  *	The implementation of setnetgrent()/getnetgrent() here follows the
36  *	the 4.x code, inasmuch as the setnetgrent() routine does all the work
37  *	of traversing the netgroup graph and building a (potentially large)
38  *	list in memory, and getnetgrent() just steps down the list.
39  *
40  *	An alternative, and probably better, implementation would lazy-eval
41  *	the netgroup graph in response to getnetgrent() calls (though
42  *	setnetgrent() should still check for the top-level netgroup name
43  *	and return NSS_SUCCESS / NSS_NOTFOUND).
44  */
45 
46 #include "files_common.h"
47 #include <ctype.h>
48 #include <rpcsvc/ypclnt.h>
49 #include <malloc.h>
50 #include <string.h>
51 #include <ctype.h>
52 #include <sys/sysmacros.h>
53 
54 /*
55  * Tricky debug support
56  */
57 
58 #pragma weak __nss_files_netgr_debug
59 #pragma weak __nss_files_netgr_error
60 extern void __nss_files_netgr_debug(const char *, ...);
61 extern void __nss_files_netgr_error(const char *, ...);
62 
63 /*
64  * Start of stuff borrowed from getgrent.c
65  */
66 static uint_t
67 hash_netgrname(nss_XbyY_args_t *argp, int keyhash, const char *line,
68     int linelen)
69 {
70 	const char	*name;
71 	uint_t		namelen, i;
72 	uint_t		hash = 0;
73 
74 	if (keyhash) {
75 		name = argp->key.name;
76 		namelen = strlen(name);
77 	} else {
78 		name = line;
79 		namelen = 0;
80 		while (linelen-- && !isspace(*line)) {
81 			line++;
82 			namelen++;
83 		}
84 	}
85 
86 	for (i = 0; i < namelen; i++)
87 		hash = hash * 15 + name[i];
88 	return (hash);
89 }
90 
91 static files_hash_func hash_netgr[1] = { hash_netgrname };
92 
93 static files_hash_t hashinfo = {
94 	DEFAULTMUTEX,
95 	sizeof (struct nss_netgrent),
96 	NSS_LINELEN_NETGROUP,
97 	1,
98 	hash_netgr
99 };
100 
101 static int
102 check_netgrname(nss_XbyY_args_t *argp, const char *line, int linelen)
103 {
104 	const char *linep, *limit;
105 	const char *keyp = argp->key.name;
106 
107 	linep = line;
108 	limit = line + linelen;
109 
110 	/* +/- entries valid for compat source only */
111 	if (linelen == 0 || *line == '+' || *line == '-')
112 		return (0);
113 	while (*keyp && linep < limit && *keyp == *linep) {
114 		keyp++;
115 		linep++;
116 	}
117 	return (linep < limit && *keyp == '\0' && isspace(*linep));
118 }
119 
120 static nss_status_t
121 getbyname(files_backend_ptr_t be, void *a)
122 {
123 	return (_nss_files_XY_hash(be, a, 1, &hashinfo, 0, check_netgrname));
124 }
125 
126 /*
127  * End of stuff borrowed from getgrent.c
128  *
129  * Now some "glue" functions based loosely on
130  *   lib/libc/port/gen/getgrnam_r.c
131  */
132 
133 
134 /*
135  * This is a special purpose str2ent (parse) function used only in
136  * the _nss_files_getbyname() below.  A general-purpose version of
137  * this parser would copy the incoming line buffer to the passed
138  * temporary buffer, and fill in the passed struct nss_netgrent with
139  * pointers into that temporary buffer.  Our caller only needs the
140  * list of members of this netgroup, and since that string already
141  * exists in ready-to-use form in the incoming line buffer, we just
142  * use that.  Also special here is the fact that we allocate a copy
143  * of the member list, both because the caller wants it allocated,
144  * and because the buffer at *instr will change after we return.
145  * The caller passes null for a temporary buffer, which we ignore.
146  *
147  * See the test program: cmd/nsstest/netgr_get.c
148  * for a more generic version of this function.
149  */
150 static int
151 str2netgr(const char *instr, int lenstr, void *ent, char *buffer, int buflen)
152 {
153 	const char sep[] = " \t\n";
154 	struct nss_netgrent *netgr = ent;
155 	const char *p;
156 
157 	/* skip leading space */
158 	p = instr;
159 	while (isspace(*p))
160 		p++;
161 
162 	/* should be at the key */
163 	if (*p == '\0')
164 		return (NSS_STR_PARSE_PARSE);
165 	/* Full parser would set netgr_name = p here. */
166 
167 	/* skip the key ... */
168 	p = strpbrk(p, sep);
169 	if (p == NULL)
170 		return (NSS_STR_PARSE_PARSE);
171 	/* Full parser would store a null at *p here. */
172 
173 	/* skip separators */
174 	while (isspace(*p))
175 		p++;
176 
177 	/*
178 	 * Should be at the members list, which is the
179 	 * rest of the input line.
180 	 */
181 	if (*p == '\0')
182 		return (NSS_STR_PARSE_PARSE);
183 
184 	/*
185 	 * Caller wants this allocated.  Do it now,
186 	 * before the inbuf gets re-used.
187 	 */
188 	netgr->netgr_members = strdup(p);
189 	if (netgr->netgr_members == NULL)
190 		return (NSS_STR_PARSE_PARSE);
191 
192 	return (NSS_STR_PARSE_SUCCESS);
193 }
194 
195 /*
196  * This is a compatibility "shim" used by top_down() to get
197  * the list of members for some netgroup.  On success, the
198  * list of members is returned in allocated memory via valp.
199  */
200 static nss_status_t
201 netgr_get_members(struct files_backend *be,
202     const char *name, char **valp)
203 {
204 	struct nss_netgrent netgr;
205 	nss_XbyY_args_t args;
206 	nss_status_t result;
207 
208 	if (name == (const char *)NULL)
209 		return (NSS_ERROR);
210 
211 	(void) memset(&netgr, '\0', sizeof (netgr));
212 	(void) memset(&args, '\0', sizeof (args));
213 	args.buf.result = &netgr;
214 	args.str2ent = str2netgr;
215 	args.key.name = name;
216 	result = getbyname(be, &args);
217 
218 	if (result == NSS_SUCCESS) {
219 		/* Note: allocated memory. */
220 		*valp = netgr.netgr_members;
221 		if (*valp == NULL)
222 			result = NSS_UNAVAIL;
223 	}
224 
225 	return (result);
226 }
227 
228 
229 /*
230  * End "glue" functions
231  *
232  * The rest of this is based on:
233  *  lib/nsswitch/nis/common/getnetgrent.c
234  */
235 
236 
237 /*
238  * The nss_backend_t for a getnetgrent() sequence;  we actually give the
239  *   netgroup frontend a pointer to one of these structures in response to
240  *   a (successful) setnetgrent() call on the files_backend backend
241  *   described further down in this file.
242  */
243 
244 struct files_getnetgr_be;
245 typedef nss_status_t	(*files_getnetgr_op_t)(
246 	struct files_getnetgr_be *, void *);
247 
248 struct files_getnetgr_be {
249 	files_getnetgr_op_t	*ops;
250 	nss_dbop_t		n_ops;
251 	/*
252 	 * State for set/get/endnetgrent()
253 	 */
254 	char			*netgroup;
255 	struct grouplist	*all_members;
256 	struct grouplist	*next_member;
257 };
258 
259 struct grouplist {  /* One element of the list generated by a setnetgrent() */
260 	char			*triple[NSS_NETGR_N];
261 	struct	grouplist	*gl_nxt;
262 };
263 
264 static nss_status_t
265 getnetgr_set(struct files_getnetgr_be *be, void *a)
266 {
267 	const char		*netgroup = (const char *) a;
268 
269 	if (be->netgroup != NULL &&
270 	    strcmp(be->netgroup, netgroup) == 0) {
271 		/* We already have the member-list;  regurgitate it */
272 		be->next_member = be->all_members;
273 		return (NSS_SUCCESS);
274 	}
275 	return (NSS_NOTFOUND);
276 }
277 
278 static nss_status_t
279 getnetgr_get(struct files_getnetgr_be *be, void *a)
280 {
281 	struct nss_getnetgrent_args *args = (struct nss_getnetgrent_args *)a;
282 	struct grouplist	*mem;
283 
284 	if ((mem = be->next_member) == 0) {
285 		args->status = NSS_NETGR_NO;
286 	} else {
287 		char			*buffer	= args->buffer;
288 		int			buflen	= args->buflen;
289 		enum nss_netgr_argn	i;
290 
291 		args->status = NSS_NETGR_FOUND;
292 
293 		for (i = 0;  i < NSS_NETGR_N;  i++) {
294 			const char	*str;
295 			ssize_t	len;
296 
297 			if ((str = mem->triple[i]) == 0) {
298 				args->retp[i] = NULL;
299 			} else if ((len = strlen(str) + 1) <= buflen) {
300 				args->retp[i] = buffer;
301 				(void) memcpy(buffer, str, len);
302 				buffer += len;
303 				buflen -= len;
304 			} else {
305 				args->status = NSS_NETGR_NOMEM;
306 				break;
307 			}
308 		}
309 		be->next_member	= mem->gl_nxt;
310 	}
311 	return (NSS_SUCCESS);	/* Yup, even for end-of-list, i.e. */
312 				/* do NOT advance to next backend. */
313 }
314 
315 static nss_status_t
316 getnetgr_end(struct files_getnetgr_be *be, void *dummy)
317 {
318 	struct grouplist	*gl;
319 	struct grouplist	*next;
320 
321 	for (gl = be->all_members; gl != NULL; gl = next) {
322 		enum nss_netgr_argn	i;
323 
324 		next = gl->gl_nxt;
325 		for (i = NSS_NETGR_MACHINE; i < NSS_NETGR_N; i++) {
326 			free(gl->triple[i]);
327 		}
328 		free(gl);
329 	}
330 	be->all_members = NULL;
331 	be->next_member = NULL;
332 	free(be->netgroup);
333 	be->netgroup = NULL;
334 	return (NSS_SUCCESS);
335 }
336 
337 static nss_status_t
338 getnetgr_destr(struct files_getnetgr_be	*be, void *dummy)
339 {
340 	if (be != NULL) {
341 		(void) getnetgr_end(be, NULL);
342 		free(be);
343 	}
344 	return (NSS_SUCCESS);
345 }
346 
347 static files_getnetgr_op_t getnetgr_ops[] = {
348 	getnetgr_destr,
349 	getnetgr_end,
350 	getnetgr_set,
351 	getnetgr_get,	/* getnetgrent_r() */
352 };
353 
354 
355 /*
356  * The nss_backend_t for innetgr() and setnetgrent().
357  * Also getbyname(), but that's only for testing.
358  */
359 
360 
361 
362 /*
363  * Code to do top-down search in the graph defined by the 'netgroup' YP map
364  */
365 
366 /*
367  * ===> This code is now used for setnetgrent(), not just innetgr().
368  *
369  * If the easy way doesn't pan out, recursively search the 'netgroup' map.
370  * In order to do this, we:
371  *
372  *    -	remember all the netgroup names we've seen during this search,
373  *	whether or not we've expanded them yet (we want fast insertion
374  *	with duplicate-detection, so use yet another chained hash table),
375  *
376  *    -	keep a list of all the netgroups we haven't expanded yet (we just
377  *	want fast insertion and pop-first, so a linked list will do fine).
378  *	If we insert at the head, we get a depth-first search;  insertion
379  *	at the tail gives breadth-first (?), which seems preferable (?).
380  *
381  * A netgrnam struct contains pointers for both the hash-table and the list.
382  * It also contains the netgroup name;  note that we embed the name at the
383  * end of the structure rather than holding a pointer to yet another
384  * malloc()ed region.
385  *
386  * A netgrtab structure contains the hash-chain heads and the head/tail
387  * pointers for the expansion list.
388  */
389 
390 struct netgrnam {
391 	struct netgrnam	*hash_chain;
392 	struct netgrnam	*expand_next;
393 	char		name[1];	/* Really [strlen(name) + 1] */
394 };
395 
396 #define	HASHMOD	113
397 
398 struct netgrtab {
399 	struct netgrnam	*expand_first;
400 	struct netgrnam	**expand_lastp;
401 	struct netgrnam	*hash_heads[HASHMOD];
402 };
403 
404 static void
405 ngt_init(struct netgrtab *ngt)
406 {
407 	(void) memset((void *)ngt, '\0', sizeof (*ngt));
408 	ngt->expand_lastp = &ngt->expand_first;
409 }
410 
411 /* === ? Change ngt_init() and ngt_destroy() to malloc/free struct netgrtab */
412 
413 static void
414 /* ==> ? Should return 'failed' (out-of-memory) status ? */
415 ngt_insert(struct netgrtab *ngt, const char *name, size_t namelen)
416 {
417 	unsigned	hashval;
418 	size_t		i;
419 	struct netgrnam	*cur;
420 	struct netgrnam	**head;
421 
422 	if (__nss_files_netgr_debug != NULL) {
423 		__nss_files_netgr_debug(
424 		    "ngt_insert: ngt=%p names=%s", ngt, name);
425 	}
426 
427 	for (hashval = 0, i = 0;  i < namelen;  i++) {
428 		hashval = (hashval << 2) + hashval +
429 		    ((const unsigned char *)name)[i];
430 	}
431 	head = &ngt->hash_heads[hashval % HASHMOD];
432 	for (cur = *head;  cur != 0;  cur = cur->hash_chain) {
433 		if (strncmp(cur->name, name, namelen) == 0 &&
434 		    cur->name[namelen] == 0) {
435 			return;		/* Already in table, do nothing */
436 		}
437 	}
438 	/* Create new netgrnam struct */
439 	cur = malloc(offsetof(struct netgrnam, name) + namelen + 1);
440 	if (cur == NULL) {
441 		return;			/* Out of memory, too bad */
442 	}
443 	(void) memcpy(cur->name, name, namelen);
444 	cur->name[namelen] = '\0';
445 
446 	/* Insert in hash table */
447 	cur->hash_chain = *head;
448 	*head = cur;
449 
450 	/* Insert in expansion list (insert at end for breadth-first search */
451 	cur->expand_next = NULL;
452 	*ngt->expand_lastp = cur;
453 	ngt->expand_lastp = &cur->expand_next;
454 }
455 
456 static const char *
457 ngt_next(struct netgrtab *ngt)
458 {
459 	struct netgrnam	*first;
460 
461 	if ((first = ngt->expand_first) == NULL) {
462 		return (NULL);
463 	}
464 	if ((ngt->expand_first = first->expand_next) == NULL) {
465 		ngt->expand_lastp = &ngt->expand_first;
466 	}
467 	return (first->name);
468 }
469 
470 static void
471 ngt_destroy(struct netgrtab *ngt)
472 {
473 	struct netgrnam	*cur;
474 	struct netgrnam *next;
475 	int		i;
476 
477 	for (i = 0;  i < HASHMOD;  i++) {
478 		for (cur = ngt->hash_heads[i]; cur != NULL; ) {
479 			next = cur->hash_chain;
480 			free(cur);
481 			cur = next;
482 		}
483 	}
484 	/* Don't bother zeroing pointers;  must do init if we want to reuse */
485 }
486 
487 typedef const char *ccp;
488 
489 static nss_status_t
490 top_down(struct files_backend *be, const char **groups, int ngroups,
491     int (*func)(ccp triple[3], void *iter_args, nss_status_t *return_val),
492     void *iter_args)
493 {
494 	struct netgrtab		*ngt;
495 	/* netgrtab goes on the heap, not the stack, because it's large and */
496 	/* stacks may not be all that big in multi-threaded programs. */
497 
498 	const char		*group;
499 	int			nfound;
500 	int			done;
501 	nss_status_t		result;
502 
503 	if ((ngt = malloc(sizeof (*ngt))) == NULL) {
504 		return (NSS_UNAVAIL);
505 	}
506 	ngt_init(ngt);
507 
508 	while (ngroups > 0) {
509 		ngt_insert(ngt, *groups, strlen(*groups));
510 		groups++;
511 		ngroups--;
512 	}
513 
514 	done	= 0;	/* Set to 1 to indicate that we cut the iteration  */
515 			/*   short (and 'result' holds the return value)   */
516 	nfound	= 0;	/* Number of successful netgroup getbyname calls   */
517 
518 	while (!done && (group = ngt_next(ngt)) != NULL) {
519 		char		*val = NULL;
520 		char		*p;
521 
522 		result = netgr_get_members(be, group, &val);
523 		if (result != NSS_SUCCESS) {
524 			if (result == NSS_NOTFOUND) {
525 				if (__nss_files_netgr_error != NULL)
526 					__nss_files_netgr_error(
527 			    "files netgroup lookup: %s doesn't exist",
528 					    group);
529 			} else {
530 				if (__nss_files_netgr_error != NULL)
531 					__nss_files_netgr_error(
532 			"files netgroup lookup: getbyname returned [%s]",
533 					    strerror(errno));
534 				done = 1;	/* Give up, return result */
535 			}
536 			/* Don't need to clean up anything */
537 			continue;
538 		}
539 
540 		if (__nss_files_netgr_debug != NULL) {
541 			__nss_files_netgr_debug(
542 			    "ngt_top: ngt=%p grp=%s members=\"%s\"",
543 			    ngt, group, val);
544 		}
545 
546 		nfound++;
547 
548 		if ((p = strpbrk(val, "#\n")) != NULL) {
549 			*p = '\0';
550 		}
551 		p = val;
552 
553 		/* Parse val into triples and recursive netgroup references */
554 		for (;;) {
555 			ccp			triple[NSS_NETGR_N];
556 			int			syntax_err;
557 			enum nss_netgr_argn	i;
558 
559 			while (isspace(*p))
560 				p++;
561 			if (*p == '\0') {
562 				/* Finished processing this particular val */
563 				break;
564 			}
565 			if (*p != '(') {
566 				/* Doesn't look like the start of a triple, */
567 				/*   so assume it's a recursive netgroup.   */
568 				char *start = p;
569 				p = strpbrk(start, " \t");
570 				if (p == 0) {
571 					/* Point p at the final '\0' */
572 					p = start + strlen(start);
573 				}
574 				ngt_insert(ngt, start, (size_t)(p - start));
575 				continue;
576 			}
577 
578 			/* Main case:  a (machine, user, domain) triple */
579 			p++;
580 			syntax_err = 0;
581 			for (i = NSS_NETGR_MACHINE; i < NSS_NETGR_N; i++) {
582 				char		*start;
583 				char		*limit;
584 				const char	*terminators = ",) \t";
585 
586 				if (i == NSS_NETGR_DOMAIN) {
587 					/* Don't allow comma */
588 					terminators++;
589 				}
590 				while (isspace(*p))
591 					p++;
592 				start = p;
593 				limit = strpbrk(start, terminators);
594 				if (limit == 0) {
595 					syntax_err++;
596 					break;
597 				}
598 				p = limit;
599 				while (isspace(*p))
600 					p++;
601 				if (*p == terminators[0]) {
602 					/*
603 					 * Successfully parsed this name and
604 					 *   the separator after it (comma or
605 					 *   right paren); leave p ready for
606 					 *   next parse.
607 					 */
608 					p++;
609 					if (start == limit) {
610 						/* Wildcard */
611 						triple[i] = 0;
612 					} else {
613 						*limit = '\0';
614 						triple[i] = start;
615 					}
616 				} else {
617 					syntax_err++;
618 					break;
619 				}
620 			}
621 
622 			if (syntax_err) {
623 /*
624  * ===> log it;
625  * ===> try skipping past next ')';  failing that, abandon the line;
626  */
627 				break;	/* Abandon this line */
628 			} else if ((*func)(triple, iter_args, &result) == 0) {
629 				/* Return result, good or bad */
630 				done = 1;
631 				break;
632 			}
633 		}
634 		/* End of inner loop over val[] */
635 		free(val);
636 		val = NULL;
637 	}
638 	/* End of outer loop (!done && ngt_next(ngt) != 0) */
639 
640 	ngt_destroy(ngt);
641 	free(ngt);
642 
643 	if (done) {
644 		return (result);
645 	} else if (nfound > 0) {
646 		/* ==== ? Should only do this if all the top-level groups */
647 		/*	  exist in YP?					  */
648 		return (NSS_SUCCESS);
649 	} else {
650 		return (NSS_NOTFOUND);
651 	}
652 }
653 
654 
655 /*
656  * Code for setnetgrent()
657  */
658 
659 /*
660  * Iterator function for setnetgrent():  copy triple, add to be->all_members
661  */
662 static int
663 save_triple(ccp trippp[NSS_NETGR_N], void *headp_arg,
664     nss_status_t *return_val)
665 {
666 	struct grouplist	**headp = headp_arg;
667 	struct grouplist	*gl;
668 	enum nss_netgr_argn	i;
669 
670 	if (__nss_files_netgr_debug != NULL) {
671 		__nss_files_netgr_debug(
672 		    "save_tripple: h=%s u=%s d=%s",
673 		    trippp[0] ? trippp[0] : "*",
674 		    trippp[1] ? trippp[1] : "*",
675 		    trippp[2] ? trippp[2] : "*");
676 	}
677 
678 	if ((gl = malloc(sizeof (*gl))) == NULL) {
679 		/* Out of memory */
680 		*return_val = NSS_UNAVAIL;
681 		return (0);
682 	}
683 	for (i = NSS_NETGR_MACHINE;  i < NSS_NETGR_N;  i++) {
684 		if (trippp[i] == NULL) {
685 			/* Wildcard */
686 			gl->triple[i] = NULL;
687 		} else if ((gl->triple[i] = strdup(trippp[i])) == NULL) {
688 			/* Out of memory.  Free any we've allocated */
689 			enum nss_netgr_argn	j;
690 
691 			for (j = NSS_NETGR_MACHINE;  j < i;  j++) {
692 				free(gl->triple[j]);
693 			}
694 			free(gl);
695 			*return_val = NSS_UNAVAIL;
696 			return (0);
697 		}
698 	}
699 	gl->gl_nxt = *headp;
700 	*headp = gl;
701 	return (1);	/* Tell top_down() to keep iterating */
702 }
703 
704 static nss_status_t
705 netgr_set(struct files_backend *be, void *a)
706 {
707 	struct nss_setnetgrent_args *args = (struct nss_setnetgrent_args *)a;
708 	struct files_getnetgr_be	*get_be;
709 	nss_status_t		res;
710 
711 	get_be = malloc(sizeof (*get_be));
712 	if (get_be == NULL) {
713 		return (NSS_UNAVAIL);
714 	}
715 
716 	get_be->all_members = NULL;
717 	res = top_down(be, &args->netgroup, 1, save_triple,
718 	    &get_be->all_members);
719 
720 	if (res == NSS_SUCCESS) {
721 		get_be->ops		= getnetgr_ops;
722 		get_be->n_ops		= ARRAY_SIZE(getnetgr_ops);
723 		get_be->netgroup	= strdup(args->netgroup);
724 		if (get_be->netgroup == NULL) {
725 			/* Out of memory. */
726 			args->iterator = NULL;
727 			free(get_be);
728 			return (NSS_UNAVAIL);
729 		}
730 		get_be->next_member	= get_be->all_members;
731 
732 		args->iterator		= (nss_backend_t *)get_be;
733 	} else {
734 		args->iterator		= NULL;
735 		free(get_be);
736 	}
737 	return (res);
738 }
739 
740 
741 /*
742  * Code for innetgr()
743  */
744 
745 /*
746  * Iterator function for innetgr():  Check whether triple matches args
747  */
748 static int
749 match_triple(ccp triple[NSS_NETGR_N], void *ia_arg, nss_status_t *return_val)
750 {
751 	struct nss_innetgr_args	*ia = ia_arg;
752 	enum nss_netgr_argn	i;
753 
754 	if (__nss_files_netgr_debug != NULL) {
755 		__nss_files_netgr_debug(
756 		    "match_triple: h=%s u=%s d=%s",
757 		    triple[0] ? triple[0] : "*",
758 		    triple[1] ? triple[1] : "*",
759 		    triple[2] ? triple[2] : "*");
760 	}
761 
762 	for (i = NSS_NETGR_MACHINE;  i < NSS_NETGR_N;  i++) {
763 		int		(*cmpf)(const char *, const char *);
764 		char		**argv;
765 		uint_t		n;
766 		const char	*name = triple[i];
767 		int		argc = ia->arg[i].argc;
768 
769 		if (argc == 0 || name == NULL) {
770 			/* Wildcarded on one side or t'other */
771 			continue;
772 		}
773 		argv = ia->arg[i].argv;
774 		cmpf = (i == NSS_NETGR_MACHINE) ? strcasecmp : strcmp;
775 		for (n = 0;  n < argc;  n++) {
776 			if ((*cmpf)(argv[n], name) == 0) {
777 				break;
778 			}
779 		}
780 		if (n >= argc) {
781 			/* Match failed, tell top_down() to keep looking */
782 			return (1);
783 		}
784 	}
785 	/* Matched on all three, so quit looking and declare victory */
786 
787 	if (__nss_files_netgr_debug != NULL)
788 		__nss_files_netgr_debug("match_triple: found");
789 
790 	ia->status = NSS_NETGR_FOUND;
791 	*return_val = NSS_SUCCESS;
792 	return (0);
793 }
794 
795 /*
796  * Used to have easy_way() and it's support functions here.
797  */
798 
799 static nss_status_t
800 netgr_in(struct files_backend *be, void *a)
801 {
802 	struct nss_innetgr_args	*ia = (struct nss_innetgr_args *)a;
803 	nss_status_t		res;
804 
805 	ia->status = NSS_NETGR_NO;
806 
807 	/*
808 	 * Used to have "easy_way" calls here for the cases
809 	 * where we have just a user, or just a machine.
810 	 *
811 	 * That was important for NIS, where getting the list of
812 	 * members for some netgroup was a yp_match call that may
813 	 * need to go over-the-wire.  Here in the "files" backend,
814 	 * getting the members of a group (getbyname) is a strictly
815 	 * local operation, and is cached (see hashinfo above) so
816 	 * it can normally complete with just memory operations.
817 	 *
818 	 * With a low-cost getbyname operation, the simple
819 	 * top_down algorithm has acceptable performance.
820 	 */
821 
822 	/* Nope, try the slow way */
823 	ia->status = NSS_NETGR_NO;
824 	res = top_down(be, (const char **)ia->groups.argv, ia->groups.argc,
825 	    match_triple, ia);
826 	return (res);
827 }
828 
829 
830 /*
831  * (Almost) boilerplate for a switch backend
832  */
833 
834 static nss_status_t
835 netgr_destr(struct files_backend *be, void *dummy)
836 {
837 	free(be);
838 	return (NSS_SUCCESS);
839 }
840 
841 static files_backend_op_t netgroup_ops[] = {
842 	netgr_destr,
843 	NULL,		/* No endent, because no setent/getent */
844 	NULL,		/* No setent;  setnetgrent() is really a getXbyY() */
845 	NULL,		/* No getent in the normal sense */
846 
847 	netgr_in,	/* innetgr(), via NSS_DBOP_NETGROUP_IN */
848 	netgr_set,	/* setnetgrent(), via NSS_DBOP_NETGROUP_SET */
849 	getbyname,	/* For testing, via NSS_DBOP_NETGROUP_BYNAME */
850 };
851 
852 /*
853  * This is the one-and-only external entry point in this file.
854  * It's called by the NSS framework when loading this backend.
855  */
856 nss_backend_t *
857 _nss_files_netgroup_constr(const char *dummy1, const char *dummy2,
858     const char *dummy3)
859 {
860 	nss_backend_t	*be;
861 
862 	be = _nss_files_constr(netgroup_ops,
863 	    ARRAY_SIZE(netgroup_ops),
864 	    "/etc/netgroup",
865 	    NSS_LINELEN_NETGROUP,
866 	    &hashinfo);
867 
868 	return (be);
869 }
870