xref: /freebsd/lib/libc/net/nsdispatch.c (revision aa0a1e58)
1 /*	$NetBSD: nsdispatch.c,v 1.9 1999/01/25 00:16:17 lukem Exp $	*/
2 
3 /*-
4  * Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Luke Mewburn.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *        This product includes software developed by the NetBSD
21  *        Foundation, Inc. and its contributors.
22  * 4. Neither the name of The NetBSD Foundation nor the names of its
23  *    contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36  * POSSIBILITY OF SUCH DAMAGE.
37  */
38 /*-
39  * Copyright (c) 2003 Networks Associates Technology, Inc.
40  * All rights reserved.
41  *
42  * Portions of this software were developed for the FreeBSD Project by
43  * Jacques A. Vidrine, Safeport Network Services, and Network
44  * Associates Laboratories, the Security Research Division of Network
45  * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
46  * ("CBOSS"), as part of the DARPA CHATS research program.
47  *
48  * Redistribution and use in source and binary forms, with or without
49  * modification, are permitted provided that the following conditions
50  * are met:
51  * 1. Redistributions of source code must retain the above copyright
52  *    notice, this list of conditions and the following disclaimer.
53  * 2. Redistributions in binary form must reproduce the above copyright
54  *    notice, this list of conditions and the following disclaimer in the
55  *    documentation and/or other materials provided with the distribution.
56  *
57  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
58  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
59  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
60  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
61  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
62  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
63  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
64  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
65  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
66  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
67  * SUCH DAMAGE.
68  *
69  */
70 #include <sys/cdefs.h>
71 __FBSDID("$FreeBSD$");
72 
73 #include "namespace.h"
74 #include <sys/param.h>
75 #include <sys/stat.h>
76 
77 #include <dlfcn.h>
78 #include <errno.h>
79 #include <fcntl.h>
80 #define _NS_PRIVATE
81 #include <nsswitch.h>
82 #include <pthread.h>
83 #include <pthread_np.h>
84 #include <stdio.h>
85 #include <stdlib.h>
86 #include <string.h>
87 #include <syslog.h>
88 #include <unistd.h>
89 #include "un-namespace.h"
90 #include "nss_tls.h"
91 #include "libc_private.h"
92 #ifdef NS_CACHING
93 #include "nscache.h"
94 #endif
95 
96 enum _nss_constants {
97 	/* Number of elements allocated when we grow a vector */
98 	ELEMSPERCHUNK =	8
99 };
100 
101 /*
102  * Global NSS data structures are mostly read-only, but we update
103  * them when we read or re-read the nsswitch.conf.
104  */
105 static	pthread_rwlock_t	nss_lock = PTHREAD_RWLOCK_INITIALIZER;
106 
107 /*
108  * Runtime determination of whether we are dynamically linked or not.
109  */
110 extern	int		_DYNAMIC __attribute__ ((weak));
111 #define	is_dynamic()	(&_DYNAMIC != NULL)
112 
113 /*
114  * default sourcelist: `files'
115  */
116 const ns_src __nsdefaultsrc[] = {
117 	{ NSSRC_FILES, NS_SUCCESS },
118 	{ 0 },
119 };
120 
121 /* Database, source mappings. */
122 static	unsigned int		 _nsmapsize;
123 static	ns_dbt			*_nsmap = NULL;
124 
125 /* NSS modules. */
126 static	unsigned int		 _nsmodsize;
127 static	ns_mod			*_nsmod;
128 
129 /* Placeholder for builtin modules' dlopen `handle'. */
130 static	int			 __nss_builtin_handle;
131 static	void			*nss_builtin_handle = &__nss_builtin_handle;
132 
133 #ifdef NS_CACHING
134 /*
135  * Cache lookup cycle prevention function - if !NULL then no cache lookups
136  * will be made
137  */
138 static	void			*nss_cache_cycle_prevention_func = NULL;
139 #endif
140 
141 /*
142  * When this is set to 1, nsdispatch won't use nsswitch.conf
143  * but will consult the 'defaults' source list only.
144  * NOTE: nested fallbacks (when nsdispatch calls fallback functions,
145  *     which in turn calls nsdispatch, which should call fallback
146  *     function) are not supported
147  */
148 struct fb_state {
149 	int	fb_dispatch;
150 };
151 static	void	fb_endstate(void *);
152 NSS_TLS_HANDLING(fb);
153 
154 /*
155  * Attempt to spew relatively uniform messages to syslog.
156  */
157 #define nss_log(level, fmt, ...) \
158 	syslog((level), "NSSWITCH(%s): " fmt, __func__, __VA_ARGS__)
159 #define nss_log_simple(level, s) \
160 	syslog((level), "NSSWITCH(%s): " s, __func__)
161 
162 /*
163  * Dynamically growable arrays are used for lists of databases, sources,
164  * and modules.  The following `vector' interface is used to isolate the
165  * common operations.
166  */
167 typedef	int	(*vector_comparison)(const void *, const void *);
168 typedef	void	(*vector_free_elem)(void *);
169 static	void	  vector_sort(void *, unsigned int, size_t,
170 		    vector_comparison);
171 static	void	  vector_free(void *, unsigned int *, size_t,
172 		    vector_free_elem);
173 static	void	 *vector_ref(unsigned int, void *, unsigned int, size_t);
174 static	void	 *vector_search(const void *, void *, unsigned int, size_t,
175 		    vector_comparison);
176 static	void	 *vector_append(const void *, void *, unsigned int *, size_t);
177 
178 
179 /*
180  * Internal interfaces.
181  */
182 static	int	 string_compare(const void *, const void *);
183 static	int	 mtab_compare(const void *, const void *);
184 static	int	 nss_configure(void);
185 static	void	 ns_dbt_free(ns_dbt *);
186 static	void	 ns_mod_free(ns_mod *);
187 static	void	 ns_src_free(ns_src **, int);
188 static	void	 nss_load_builtin_modules(void);
189 static	void	 nss_load_module(const char *, nss_module_register_fn);
190 static	void	 nss_atexit(void);
191 /* nsparser */
192 extern	FILE	*_nsyyin;
193 
194 
195 /*
196  * The vector operations
197  */
198 static void
199 vector_sort(void *vec, unsigned int count, size_t esize,
200     vector_comparison comparison)
201 {
202 	qsort(vec, count, esize, comparison);
203 }
204 
205 
206 static void *
207 vector_search(const void *key, void *vec, unsigned int count, size_t esize,
208     vector_comparison comparison)
209 {
210 	return (bsearch(key, vec, count, esize, comparison));
211 }
212 
213 
214 static void *
215 vector_append(const void *elem, void *vec, unsigned int *count, size_t esize)
216 {
217 	void	*p;
218 
219 	if ((*count % ELEMSPERCHUNK) == 0) {
220 		p = realloc(vec, (*count + ELEMSPERCHUNK) * esize);
221 		if (p == NULL) {
222 			nss_log_simple(LOG_ERR, "memory allocation failure");
223 			return (vec);
224 		}
225 		vec = p;
226 	}
227 	memmove((void *)(((uintptr_t)vec) + (*count * esize)), elem, esize);
228 	(*count)++;
229 	return (vec);
230 }
231 
232 
233 static void *
234 vector_ref(unsigned int i, void *vec, unsigned int count, size_t esize)
235 {
236 	if (i < count)
237 		return (void *)((uintptr_t)vec + (i * esize));
238 	else
239 		return (NULL);
240 }
241 
242 
243 #define VECTOR_FREE(v, c, s, f) \
244 	do { vector_free(v, c, s, f); v = NULL; } while (0)
245 static void
246 vector_free(void *vec, unsigned int *count, size_t esize,
247     vector_free_elem free_elem)
248 {
249 	unsigned int	 i;
250 	void		*elem;
251 
252 	for (i = 0; i < *count; i++) {
253 		elem = vector_ref(i, vec, *count, esize);
254 		if (elem != NULL)
255 			free_elem(elem);
256 	}
257 	free(vec);
258 	*count = 0;
259 }
260 
261 /*
262  * Comparison functions for vector_search.
263  */
264 static int
265 string_compare(const void *a, const void *b)
266 {
267       return (strcasecmp(*(const char * const *)a, *(const char * const *)b));
268 }
269 
270 
271 static int
272 mtab_compare(const void *a, const void *b)
273 {
274       int     cmp;
275 
276       cmp = strcmp(((const ns_mtab *)a)->name, ((const ns_mtab *)b)->name);
277       if (cmp != 0)
278 	      return (cmp);
279       else
280 	      return (strcmp(((const ns_mtab *)a)->database,
281 		  ((const ns_mtab *)b)->database));
282 }
283 
284 /*
285  * NSS nsmap management.
286  */
287 void
288 _nsdbtaddsrc(ns_dbt *dbt, const ns_src *src)
289 {
290 	const ns_mod	*modp;
291 
292 	dbt->srclist = vector_append(src, dbt->srclist, &dbt->srclistsize,
293 	    sizeof(*src));
294 	modp = vector_search(&src->name, _nsmod, _nsmodsize, sizeof(*_nsmod),
295 	    string_compare);
296 	if (modp == NULL)
297 		nss_load_module(src->name, NULL);
298 }
299 
300 
301 #ifdef _NSS_DEBUG
302 void
303 _nsdbtdump(const ns_dbt *dbt)
304 {
305 	int i;
306 
307 	printf("%s (%d source%s):", dbt->name, dbt->srclistsize,
308 	    dbt->srclistsize == 1 ? "" : "s");
309 	for (i = 0; i < (int)dbt->srclistsize; i++) {
310 		printf(" %s", dbt->srclist[i].name);
311 		if (!(dbt->srclist[i].flags &
312 		    (NS_UNAVAIL|NS_NOTFOUND|NS_TRYAGAIN)) &&
313 		    (dbt->srclist[i].flags & NS_SUCCESS))
314 			continue;
315 		printf(" [");
316 		if (!(dbt->srclist[i].flags & NS_SUCCESS))
317 			printf(" SUCCESS=continue");
318 		if (dbt->srclist[i].flags & NS_UNAVAIL)
319 			printf(" UNAVAIL=return");
320 		if (dbt->srclist[i].flags & NS_NOTFOUND)
321 			printf(" NOTFOUND=return");
322 		if (dbt->srclist[i].flags & NS_TRYAGAIN)
323 			printf(" TRYAGAIN=return");
324 		printf(" ]");
325 	}
326 	printf("\n");
327 }
328 #endif
329 
330 
331 /*
332  * The first time nsdispatch is called (during a process's lifetime,
333  * or after nsswitch.conf has been updated), nss_configure will
334  * prepare global data needed by NSS.
335  */
336 static int
337 nss_configure(void)
338 {
339 	static pthread_mutex_t conf_lock = PTHREAD_MUTEX_INITIALIZER;
340 	static time_t	 confmod;
341 	struct stat	 statbuf;
342 	int		 result, isthreaded;
343 	const char	*path;
344 #ifdef NS_CACHING
345 	void		*handle;
346 #endif
347 
348 	result = 0;
349 	isthreaded = __isthreaded;
350 #if defined(_NSS_DEBUG) && defined(_NSS_SHOOT_FOOT)
351 	/* NOTE WELL:  THIS IS A SECURITY HOLE. This must only be built
352 	 * for debugging purposes and MUST NEVER be used in production.
353 	 */
354 	path = getenv("NSSWITCH_CONF");
355 	if (path == NULL)
356 #endif
357 	path = _PATH_NS_CONF;
358 	if (stat(path, &statbuf) != 0)
359 		return (0);
360 	if (statbuf.st_mtime <= confmod)
361 		return (0);
362 	if (isthreaded) {
363 	    result = _pthread_mutex_trylock(&conf_lock);
364 	    if (result != 0)
365 		    return (0);
366 	    (void)_pthread_rwlock_unlock(&nss_lock);
367 	    result = _pthread_rwlock_wrlock(&nss_lock);
368 	    if (result != 0)
369 		    goto fin2;
370 	}
371 	_nsyyin = fopen(path, "r");
372 	if (_nsyyin == NULL)
373 		goto fin;
374 	VECTOR_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
375 	    (vector_free_elem)ns_dbt_free);
376 	VECTOR_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
377 	    (vector_free_elem)ns_mod_free);
378 	nss_load_builtin_modules();
379 	_nsyyparse();
380 	(void)fclose(_nsyyin);
381 	vector_sort(_nsmap, _nsmapsize, sizeof(*_nsmap), string_compare);
382 	if (confmod == 0)
383 		(void)atexit(nss_atexit);
384 	confmod = statbuf.st_mtime;
385 
386 #ifdef NS_CACHING
387 	handle = dlopen(NULL, RTLD_LAZY | RTLD_GLOBAL);
388 	if (handle != NULL) {
389 		nss_cache_cycle_prevention_func = dlsym(handle,
390 			"_nss_cache_cycle_prevention_function");
391 		dlclose(handle);
392 	}
393 #endif
394 fin:
395 	if (isthreaded) {
396 	    (void)_pthread_rwlock_unlock(&nss_lock);
397 	    if (result == 0)
398 		    result = _pthread_rwlock_rdlock(&nss_lock);
399 	}
400 fin2:
401 	if (isthreaded)
402 		(void)_pthread_mutex_unlock(&conf_lock);
403 	return (result);
404 }
405 
406 
407 void
408 _nsdbtput(const ns_dbt *dbt)
409 {
410 	unsigned int	 i;
411 	ns_dbt		*p;
412 
413 	for (i = 0; i < _nsmapsize; i++) {
414 		p = vector_ref(i, _nsmap, _nsmapsize, sizeof(*_nsmap));
415 		if (string_compare(&dbt->name, &p->name) == 0) {
416 			/* overwrite existing entry */
417 			if (p->srclist != NULL)
418 				ns_src_free(&p->srclist, p->srclistsize);
419 			memmove(p, dbt, sizeof(*dbt));
420 			return;
421 		}
422 	}
423 	_nsmap = vector_append(dbt, _nsmap, &_nsmapsize, sizeof(*_nsmap));
424 }
425 
426 
427 static void
428 ns_dbt_free(ns_dbt *dbt)
429 {
430 	ns_src_free(&dbt->srclist, dbt->srclistsize);
431 	if (dbt->name)
432 		free((void *)dbt->name);
433 }
434 
435 
436 static void
437 ns_src_free(ns_src **src, int srclistsize)
438 {
439 	int	i;
440 
441 	for (i = 0; i < srclistsize; i++)
442 		if ((*src)[i].name != NULL)
443 			/* This one was allocated by nslexer. You'll just
444 			 * have to trust me.
445 			 */
446 			free((void *)((*src)[i].name));
447 	free(*src);
448 	*src = NULL;
449 }
450 
451 
452 
453 /*
454  * NSS module management.
455  */
456 /* The built-in NSS modules are all loaded at once. */
457 #define NSS_BACKEND(name, reg) \
458 ns_mtab	*reg(unsigned int *, nss_module_unregister_fn *);
459 #include "nss_backends.h"
460 #undef NSS_BACKEND
461 
462 static void
463 nss_load_builtin_modules(void)
464 {
465 #define NSS_BACKEND(name, reg) nss_load_module(#name, reg);
466 #include "nss_backends.h"
467 #undef NSS_BACKEND
468 }
469 
470 
471 /* Load a built-in or dynamically linked module.  If the `reg_fn'
472  * argument is non-NULL, assume a built-in module and use reg_fn to
473  * register it.  Otherwise, search for a dynamic NSS module.
474  */
475 static void
476 nss_load_module(const char *source, nss_module_register_fn reg_fn)
477 {
478 	char		 buf[PATH_MAX];
479 	ns_mod		 mod;
480 	nss_module_register_fn fn;
481 
482 	memset(&mod, 0, sizeof(mod));
483 	mod.name = strdup(source);
484 	if (mod.name == NULL) {
485 		nss_log_simple(LOG_ERR, "memory allocation failure");
486 		return;
487 	}
488 	if (reg_fn != NULL) {
489 		/* The placeholder is required, as a NULL handle
490 		 * represents an invalid module.
491 		 */
492 		mod.handle = nss_builtin_handle;
493 		fn = reg_fn;
494 	} else if (!is_dynamic())
495 		goto fin;
496 	else {
497 		if (snprintf(buf, sizeof(buf), "nss_%s.so.%d", mod.name,
498 		    NSS_MODULE_INTERFACE_VERSION) >= (int)sizeof(buf))
499 			goto fin;
500 		mod.handle = dlopen(buf, RTLD_LOCAL|RTLD_LAZY);
501 		if (mod.handle == NULL) {
502 #ifdef _NSS_DEBUG
503 			/* This gets pretty annoying since the built-in
504 			 * sources aren't modules yet.
505 			 */
506 			nss_log(LOG_DEBUG, "%s, %s", mod.name, dlerror());
507 #endif
508 			goto fin;
509 		}
510 		fn = (nss_module_register_fn)dlfunc(mod.handle,
511 		    "nss_module_register");
512 		if (fn == NULL) {
513 			(void)dlclose(mod.handle);
514 			mod.handle = NULL;
515 			nss_log(LOG_ERR, "%s, %s", mod.name, dlerror());
516 			goto fin;
517 		}
518 	}
519 	mod.mtab = fn(mod.name, &mod.mtabsize, &mod.unregister);
520 	if (mod.mtab == NULL || mod.mtabsize == 0) {
521 		if (mod.handle != nss_builtin_handle)
522 			(void)dlclose(mod.handle);
523 		mod.handle = NULL;
524 		nss_log(LOG_ERR, "%s, registration failed", mod.name);
525 		goto fin;
526 	}
527 	if (mod.mtabsize > 1)
528 		qsort(mod.mtab, mod.mtabsize, sizeof(mod.mtab[0]),
529 		    mtab_compare);
530 fin:
531 	_nsmod = vector_append(&mod, _nsmod, &_nsmodsize, sizeof(*_nsmod));
532 	vector_sort(_nsmod, _nsmodsize, sizeof(*_nsmod), string_compare);
533 }
534 
535 
536 
537 static void
538 ns_mod_free(ns_mod *mod)
539 {
540 
541 	free(mod->name);
542 	if (mod->handle == NULL)
543 		return;
544 	if (mod->unregister != NULL)
545 		mod->unregister(mod->mtab, mod->mtabsize);
546 	if (mod->handle != nss_builtin_handle)
547 		(void)dlclose(mod->handle);
548 }
549 
550 
551 
552 /*
553  * Cleanup
554  */
555 static void
556 nss_atexit(void)
557 {
558 	int isthreaded;
559 
560 	isthreaded = __isthreaded;
561 	if (isthreaded)
562 		(void)_pthread_rwlock_wrlock(&nss_lock);
563 	VECTOR_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
564 	    (vector_free_elem)ns_dbt_free);
565 	VECTOR_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
566 	    (vector_free_elem)ns_mod_free);
567 	if (isthreaded)
568 		(void)_pthread_rwlock_unlock(&nss_lock);
569 }
570 
571 
572 
573 /*
574  * Finally, the actual implementation.
575  */
576 static nss_method
577 nss_method_lookup(const char *source, const char *database,
578     const char *method, const ns_dtab disp_tab[], void **mdata)
579 {
580 	ns_mod	*mod;
581 	ns_mtab	*match, key;
582 	int	 i;
583 
584 	if (disp_tab != NULL)
585 		for (i = 0; disp_tab[i].src != NULL; i++)
586 			if (strcasecmp(source, disp_tab[i].src) == 0) {
587 				*mdata = disp_tab[i].mdata;
588 				return (disp_tab[i].method);
589 			}
590 	mod = vector_search(&source, _nsmod, _nsmodsize, sizeof(*_nsmod),
591 	    string_compare);
592 	if (mod != NULL && mod->handle != NULL) {
593 		key.database = database;
594 		key.name = method;
595 		match = bsearch(&key, mod->mtab, mod->mtabsize,
596 		    sizeof(mod->mtab[0]), mtab_compare);
597 		if (match != NULL) {
598 			*mdata = match->mdata;
599 			return (match->method);
600 		}
601 	}
602 
603 	*mdata = NULL;
604 	return (NULL);
605 }
606 
607 static void
608 fb_endstate(void *p)
609 {
610 	free(p);
611 }
612 
613 __weak_reference(_nsdispatch, nsdispatch);
614 
615 int
616 _nsdispatch(void *retval, const ns_dtab disp_tab[], const char *database,
617 	    const char *method_name, const ns_src defaults[], ...)
618 {
619 	va_list		 ap;
620 	const ns_dbt	*dbt;
621 	const ns_src	*srclist;
622 	nss_method	 method, fb_method;
623 	void		*mdata;
624 	int		 isthreaded, serrno, i, result, srclistsize;
625 	struct fb_state	*st;
626 
627 #ifdef NS_CACHING
628 	nss_cache_data	 cache_data;
629 	nss_cache_data	*cache_data_p;
630 	int		 cache_flag;
631 #endif
632 
633 	dbt = NULL;
634 	fb_method = NULL;
635 
636 	isthreaded = __isthreaded;
637 	serrno = errno;
638 	if (isthreaded) {
639 		result = _pthread_rwlock_rdlock(&nss_lock);
640 		if (result != 0) {
641 			result = NS_UNAVAIL;
642 			goto fin;
643 		}
644 	}
645 
646 	result = fb_getstate(&st);
647 	if (result != 0) {
648 		result = NS_UNAVAIL;
649 		goto fin;
650 	}
651 
652 	result = nss_configure();
653 	if (result != 0) {
654 		result = NS_UNAVAIL;
655 		goto fin;
656 	}
657 	if (st->fb_dispatch == 0) {
658 		dbt = vector_search(&database, _nsmap, _nsmapsize, sizeof(*_nsmap),
659 		    string_compare);
660 		fb_method = nss_method_lookup(NSSRC_FALLBACK, database,
661 		    method_name, disp_tab, &mdata);
662 	}
663 
664 	if (dbt != NULL) {
665 		srclist = dbt->srclist;
666 		srclistsize = dbt->srclistsize;
667 	} else {
668 		srclist = defaults;
669 		srclistsize = 0;
670 		while (srclist[srclistsize].name != NULL)
671 			srclistsize++;
672 	}
673 
674 #ifdef NS_CACHING
675 	cache_data_p = NULL;
676 	cache_flag = 0;
677 #endif
678 	for (i = 0; i < srclistsize; i++) {
679 		result = NS_NOTFOUND;
680 		method = nss_method_lookup(srclist[i].name, database,
681 		    method_name, disp_tab, &mdata);
682 
683 		if (method != NULL) {
684 #ifdef NS_CACHING
685 			if (strcmp(srclist[i].name, NSSRC_CACHE) == 0 &&
686 			    nss_cache_cycle_prevention_func == NULL) {
687 #ifdef NS_STRICT_LIBC_EID_CHECKING
688 				if (issetugid() != 0)
689 					continue;
690 #endif
691 				cache_flag = 1;
692 
693 				memset(&cache_data, 0, sizeof(nss_cache_data));
694 				cache_data.info = (nss_cache_info const *)mdata;
695 				cache_data_p = &cache_data;
696 
697 				va_start(ap, defaults);
698 				if (cache_data.info->id_func != NULL)
699 					result = __nss_common_cache_read(retval,
700 					    cache_data_p, ap);
701 				else if (cache_data.info->marshal_func != NULL)
702 					result = __nss_mp_cache_read(retval,
703 					    cache_data_p, ap);
704 				else
705 					result = __nss_mp_cache_end(retval,
706 					    cache_data_p, ap);
707 				va_end(ap);
708 			} else {
709 				cache_flag = 0;
710 				errno = 0;
711 				va_start(ap, defaults);
712 				result = method(retval, mdata, ap);
713 				va_end(ap);
714 			}
715 #else /* NS_CACHING */
716 			errno = 0;
717 			va_start(ap, defaults);
718 			result = method(retval, mdata, ap);
719 			va_end(ap);
720 #endif /* NS_CACHING */
721 
722 			if (result & (srclist[i].flags))
723 				break;
724 		} else {
725 			if (fb_method != NULL) {
726 				st->fb_dispatch = 1;
727 				va_start(ap, defaults);
728 				result = fb_method(retval,
729 				    (void *)srclist[i].name, ap);
730 				va_end(ap);
731 				st->fb_dispatch = 0;
732 			} else
733 				nss_log(LOG_DEBUG, "%s, %s, %s, not found, "
734 				    "and no fallback provided",
735 				    srclist[i].name, database, method_name);
736 		}
737 	}
738 
739 #ifdef NS_CACHING
740 	if (cache_data_p != NULL &&
741 	    (result & (NS_NOTFOUND | NS_SUCCESS)) && cache_flag == 0) {
742 		va_start(ap, defaults);
743 		if (result == NS_SUCCESS) {
744 			if (cache_data.info->id_func != NULL)
745 				__nss_common_cache_write(retval, cache_data_p,
746 				    ap);
747 			else if (cache_data.info->marshal_func != NULL)
748 				__nss_mp_cache_write(retval, cache_data_p, ap);
749 		} else if (result == NS_NOTFOUND) {
750 			if (cache_data.info->id_func == NULL) {
751 				if (cache_data.info->marshal_func != NULL)
752 					__nss_mp_cache_write_submit(retval,
753 					    cache_data_p, ap);
754 			} else
755 				__nss_common_cache_write_negative(cache_data_p);
756 		}
757 		va_end(ap);
758 	}
759 #endif /* NS_CACHING */
760 
761 	if (isthreaded)
762 		(void)_pthread_rwlock_unlock(&nss_lock);
763 fin:
764 	errno = serrno;
765 	return (result);
766 }
767