xref: /freebsd/lib/libc/net/nsdispatch.c (revision 559a218c9b257775fb249b67945fe4a05b7a6b9f)
1 /*	$NetBSD: nsdispatch.c,v 1.9 1999/01/25 00:16:17 lukem Exp $	*/
2 
3 /*-
4  * SPDX-License-Identifier: BSD-2-Clause
5  *
6  * Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc.
7  * All rights reserved.
8  *
9  * This code is derived from software contributed to The NetBSD Foundation
10  * by Luke Mewburn.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
23  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
25  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31  * POSSIBILITY OF SUCH DAMAGE.
32  */
33 /*-
34  * Copyright (c) 2003 Networks Associates Technology, Inc.
35  * All rights reserved.
36  *
37  * Portions of this software were developed for the FreeBSD Project by
38  * Jacques A. Vidrine, Safeport Network Services, and Network
39  * Associates Laboratories, the Security Research Division of Network
40  * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
41  * ("CBOSS"), as part of the DARPA CHATS research program.
42  *
43  * Redistribution and use in source and binary forms, with or without
44  * modification, are permitted provided that the following conditions
45  * are met:
46  * 1. Redistributions of source code must retain the above copyright
47  *    notice, this list of conditions and the following disclaimer.
48  * 2. Redistributions in binary form must reproduce the above copyright
49  *    notice, this list of conditions and the following disclaimer in the
50  *    documentation and/or other materials provided with the distribution.
51  *
52  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
53  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
56  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
57  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
58  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
59  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
60  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
61  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
62  * SUCH DAMAGE.
63  *
64  */
65 #include "namespace.h"
66 #include <sys/param.h>
67 #include <sys/stat.h>
68 
69 #include <dlfcn.h>
70 #include <errno.h>
71 #include <fcntl.h>
72 #define _NS_PRIVATE
73 #include <nsswitch.h>
74 #include <pthread.h>
75 #include <pthread_np.h>
76 #include <stdio.h>
77 #include <stdlib.h>
78 #include <string.h>
79 #include <syslog.h>
80 #include <unistd.h>
81 #include "un-namespace.h"
82 #include "nss_tls.h"
83 #include "libc_private.h"
84 #ifdef NS_CACHING
85 #include "nscache.h"
86 #endif
87 
88 enum _nss_constants {
89 	/* Number of elements allocated when we grow a vector */
90 	ELEMSPERCHUNK =	8
91 };
92 
93 /*
94  * Global NSS data structures are mostly read-only, but we update
95  * them when we read or re-read the nsswitch.conf.
96  */
97 static	pthread_rwlock_t	nss_lock = PTHREAD_RWLOCK_INITIALIZER;
98 
99 /*
100  * Runtime determination of whether we are dynamically linked or not.
101  */
102 extern	int		_DYNAMIC __attribute__ ((weak));
103 #define	is_dynamic()	(&_DYNAMIC != NULL)
104 
105 /*
106  * default sourcelist: `files'
107  */
108 const ns_src __nsdefaultsrc[] = {
109 	{ NSSRC_FILES, NS_SUCCESS },
110 	{ 0 },
111 };
112 
113 /* Database, source mappings. */
114 static	unsigned int		 _nsmapsize;
115 static	ns_dbt			*_nsmap = NULL;
116 
117 /* NSS modules. */
118 static	unsigned int		 _nsmodsize;
119 static	ns_mod			*_nsmod;
120 
121 /* Placeholder for builtin modules' dlopen `handle'. */
122 static	int			 __nss_builtin_handle;
123 static	void			*nss_builtin_handle = &__nss_builtin_handle;
124 
125 #ifdef NS_CACHING
126 /*
127  * Cache lookup cycle prevention function - if !NULL then no cache lookups
128  * will be made
129  */
130 static	void			*nss_cache_cycle_prevention_func = NULL;
131 #endif
132 
133 /*
134  * We keep track of nsdispatch() nesting depth in dispatch_depth.  When a
135  * fallback method is invoked from nsdispatch(), we temporarily set
136  * fallback_depth to the current dispatch depth plus one.  Subsequent
137  * calls at that exact depth will run in fallback mode (restricted to the
138  * same source as the call that was handled by the fallback method), while
139  * calls below that depth will be handled normally, allowing fallback
140  * methods to perform arbitrary lookups.
141  */
142 struct fb_state {
143 	int	dispatch_depth;
144 	int	fallback_depth;
145 };
146 static	void	fb_endstate(void *);
147 NSS_TLS_HANDLING(fb);
148 
149 /*
150  * Attempt to spew relatively uniform messages to syslog.
151  */
152 #define nss_log(level, fmt, ...) \
153 	syslog((level), "NSSWITCH(%s): " fmt, __func__, __VA_ARGS__)
154 #define nss_log_simple(level, s) \
155 	syslog((level), "NSSWITCH(%s): " s, __func__)
156 
157 /*
158  * Dynamically growable arrays are used for lists of databases, sources,
159  * and modules.  The following `vector' interface is used to isolate the
160  * common operations.
161  */
162 typedef	int	(*vector_comparison)(const void *, const void *);
163 typedef	void	(*vector_free_elem)(void *);
164 static	void	  vector_sort(void *, unsigned int, size_t,
165 		    vector_comparison);
166 static	void	  vector_free(void *, unsigned int *, size_t,
167 		    vector_free_elem);
168 static	void	 *vector_ref(unsigned int, void *, unsigned int, size_t);
169 static	void	 *vector_search(const void *, void *, unsigned int, size_t,
170 		    vector_comparison);
171 static	void	 *vector_append(const void *, void *, unsigned int *, size_t);
172 
173 
174 /*
175  * Internal interfaces.
176  */
177 static	int	 string_compare(const void *, const void *);
178 static	int	 mtab_compare(const void *, const void *);
179 static	int	 nss_configure(void);
180 static	void	 ns_dbt_free(ns_dbt *);
181 static	void	 ns_mod_free(ns_mod *);
182 static	void	 ns_src_free(ns_src **, int);
183 static	void	 nss_load_builtin_modules(void);
184 static	void	 nss_load_module(const char *, nss_module_register_fn);
185 static	void	 nss_atexit(void);
186 /* nsparser */
187 extern	FILE	*_nsyyin;
188 
189 
190 /*
191  * The vector operations
192  */
193 static void
vector_sort(void * vec,unsigned int count,size_t esize,vector_comparison comparison)194 vector_sort(void *vec, unsigned int count, size_t esize,
195     vector_comparison comparison)
196 {
197 	qsort(vec, count, esize, comparison);
198 }
199 
200 
201 static void *
vector_search(const void * key,void * vec,unsigned int count,size_t esize,vector_comparison comparison)202 vector_search(const void *key, void *vec, unsigned int count, size_t esize,
203     vector_comparison comparison)
204 {
205 	return (bsearch(key, vec, count, esize, comparison));
206 }
207 
208 
209 static void *
vector_append(const void * elem,void * vec,unsigned int * count,size_t esize)210 vector_append(const void *elem, void *vec, unsigned int *count, size_t esize)
211 {
212 	void	*p;
213 
214 	if ((*count % ELEMSPERCHUNK) == 0) {
215 		p = reallocarray(vec, *count + ELEMSPERCHUNK, esize);
216 		if (p == NULL) {
217 			nss_log_simple(LOG_ERR, "memory allocation failure");
218 			return (vec);
219 		}
220 		vec = p;
221 	}
222 	memmove((void *)(((uintptr_t)vec) + (*count * esize)), elem, esize);
223 	(*count)++;
224 	return (vec);
225 }
226 
227 
228 static void *
vector_ref(unsigned int i,void * vec,unsigned int count,size_t esize)229 vector_ref(unsigned int i, void *vec, unsigned int count, size_t esize)
230 {
231 	if (i < count)
232 		return (void *)((uintptr_t)vec + (i * esize));
233 	else
234 		return (NULL);
235 }
236 
237 
238 #define VECTOR_FREE(v, c, s, f) \
239 	do { vector_free(v, c, s, f); v = NULL; } while (0)
240 static void
vector_free(void * vec,unsigned int * count,size_t esize,vector_free_elem free_elem)241 vector_free(void *vec, unsigned int *count, size_t esize,
242     vector_free_elem free_elem)
243 {
244 	unsigned int	 i;
245 	void		*elem;
246 
247 	for (i = 0; i < *count; i++) {
248 		elem = vector_ref(i, vec, *count, esize);
249 		if (elem != NULL)
250 			free_elem(elem);
251 	}
252 	free(vec);
253 	*count = 0;
254 }
255 
256 /*
257  * Comparison functions for vector_search.
258  */
259 static int
string_compare(const void * a,const void * b)260 string_compare(const void *a, const void *b)
261 {
262       return (strcasecmp(*(const char * const *)a, *(const char * const *)b));
263 }
264 
265 
266 static int
mtab_compare(const void * a,const void * b)267 mtab_compare(const void *a, const void *b)
268 {
269       int     cmp;
270 
271       cmp = strcmp(((const ns_mtab *)a)->name, ((const ns_mtab *)b)->name);
272       if (cmp != 0)
273 	      return (cmp);
274       else
275 	      return (strcmp(((const ns_mtab *)a)->database,
276 		  ((const ns_mtab *)b)->database));
277 }
278 
279 /*
280  * NSS nsmap management.
281  */
282 void
_nsdbtaddsrc(ns_dbt * dbt,const ns_src * src)283 _nsdbtaddsrc(ns_dbt *dbt, const ns_src *src)
284 {
285 	const ns_mod	*modp;
286 
287 	dbt->srclist = vector_append(src, dbt->srclist, &dbt->srclistsize,
288 	    sizeof(*src));
289 	modp = vector_search(&src->name, _nsmod, _nsmodsize, sizeof(*_nsmod),
290 	    string_compare);
291 	if (modp == NULL)
292 		nss_load_module(src->name, NULL);
293 }
294 
295 
296 #ifdef _NSS_DEBUG
297 void
_nsdbtdump(const ns_dbt * dbt)298 _nsdbtdump(const ns_dbt *dbt)
299 {
300 	int i;
301 
302 	printf("%s (%d source%s):", dbt->name, dbt->srclistsize,
303 	    dbt->srclistsize == 1 ? "" : "s");
304 	for (i = 0; i < (int)dbt->srclistsize; i++) {
305 		printf(" %s", dbt->srclist[i].name);
306 		if (!(dbt->srclist[i].flags &
307 		    (NS_UNAVAIL|NS_NOTFOUND|NS_TRYAGAIN)) &&
308 		    (dbt->srclist[i].flags & NS_SUCCESS))
309 			continue;
310 		printf(" [");
311 		if (!(dbt->srclist[i].flags & NS_SUCCESS))
312 			printf(" SUCCESS=continue");
313 		if (dbt->srclist[i].flags & NS_UNAVAIL)
314 			printf(" UNAVAIL=return");
315 		if (dbt->srclist[i].flags & NS_NOTFOUND)
316 			printf(" NOTFOUND=return");
317 		if (dbt->srclist[i].flags & NS_TRYAGAIN)
318 			printf(" TRYAGAIN=return");
319 		printf(" ]");
320 	}
321 	printf("\n");
322 }
323 #endif
324 
325 
326 /*
327  * The first time nsdispatch is called (during a process's lifetime,
328  * or after nsswitch.conf has been updated), nss_configure will
329  * prepare global data needed by NSS.
330  */
331 static int
nss_configure(void)332 nss_configure(void)
333 {
334 	static time_t	 confmod;
335 #ifndef NS_REREAD_CONF
336 	static int	 already_initialized = 0;
337 #endif
338 	struct stat	 statbuf;
339 	int		 result, isthreaded;
340 	const char	*path;
341 #ifdef NS_CACHING
342 	void		*handle;
343 #endif
344 
345 	result = 0;
346 	isthreaded = __isthreaded;
347 #if defined(_NSS_DEBUG) && defined(_NSS_SHOOT_FOOT)
348 	/* NOTE WELL:  THIS IS A SECURITY HOLE. This must only be built
349 	 * for debugging purposes and MUST NEVER be used in production.
350 	 */
351 	path = getenv("NSSWITCH_CONF");
352 	if (path == NULL)
353 #endif
354 		path = _PATH_NS_CONF;
355 #ifndef NS_REREAD_CONF
356 	/*
357 	 * Define NS_REREAD_CONF to have nsswitch notice changes
358 	 * to nsswitch.conf(5) during runtime.  This involves calling
359 	 * stat(2) every time, which can result in performance hit.
360 	 */
361 	if (already_initialized)
362 		return (0);
363 	already_initialized = 1;
364 #endif /* NS_REREAD_CONF */
365 	if (stat(path, &statbuf) != 0)
366 		return (0);
367 	if (statbuf.st_mtime <= confmod)
368 		return (0);
369 	if (isthreaded) {
370 		(void)_pthread_rwlock_unlock(&nss_lock);
371 		result = _pthread_rwlock_wrlock(&nss_lock);
372 		if (result != 0)
373 			return (result);
374 		if (stat(path, &statbuf) != 0)
375 			goto fin;
376 		if (statbuf.st_mtime <= confmod)
377 			goto fin;
378 	}
379 	_nsyyin = fopen(path, "re");
380 	if (_nsyyin == NULL)
381 		goto fin;
382 	VECTOR_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
383 	    (vector_free_elem)ns_dbt_free);
384 	VECTOR_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
385 	    (vector_free_elem)ns_mod_free);
386 	if (confmod == 0)
387 		(void)atexit(nss_atexit);
388 	nss_load_builtin_modules();
389 	_nsyyparse();
390 	(void)fclose(_nsyyin);
391 	vector_sort(_nsmap, _nsmapsize, sizeof(*_nsmap), string_compare);
392 	confmod = statbuf.st_mtime;
393 
394 #ifdef NS_CACHING
395 	handle = libc_dlopen(NULL, RTLD_LAZY | RTLD_GLOBAL);
396 	if (handle != NULL) {
397 		nss_cache_cycle_prevention_func = dlsym(handle,
398 		    "_nss_cache_cycle_prevention_function");
399 		dlclose(handle);
400 	}
401 #endif
402 fin:
403 	if (isthreaded) {
404 		(void)_pthread_rwlock_unlock(&nss_lock);
405 		if (result == 0)
406 			result = _pthread_rwlock_rdlock(&nss_lock);
407 	}
408 	return (result);
409 }
410 
411 
412 void
_nsdbtput(const ns_dbt * dbt)413 _nsdbtput(const ns_dbt *dbt)
414 {
415 	unsigned int	 i;
416 	ns_dbt		*p;
417 
418 	for (i = 0; i < _nsmapsize; i++) {
419 		p = vector_ref(i, _nsmap, _nsmapsize, sizeof(*_nsmap));
420 		if (string_compare(&dbt->name, &p->name) == 0) {
421 			/* overwrite existing entry */
422 			if (p->srclist != NULL)
423 				ns_src_free(&p->srclist, p->srclistsize);
424 			memmove(p, dbt, sizeof(*dbt));
425 			return;
426 		}
427 	}
428 	_nsmap = vector_append(dbt, _nsmap, &_nsmapsize, sizeof(*_nsmap));
429 }
430 
431 
432 static void
ns_dbt_free(ns_dbt * dbt)433 ns_dbt_free(ns_dbt *dbt)
434 {
435 	ns_src_free(&dbt->srclist, dbt->srclistsize);
436 	if (dbt->name)
437 		free((void *)dbt->name);
438 }
439 
440 
441 static void
ns_src_free(ns_src ** src,int srclistsize)442 ns_src_free(ns_src **src, int srclistsize)
443 {
444 	int	i;
445 
446 	for (i = 0; i < srclistsize; i++)
447 		if ((*src)[i].name != NULL)
448 			/* This one was allocated by nslexer. You'll just
449 			 * have to trust me.
450 			 */
451 			free((void *)((*src)[i].name));
452 	free(*src);
453 	*src = NULL;
454 }
455 
456 
457 
458 /*
459  * NSS module management.
460  */
461 /* The built-in NSS modules are all loaded at once. */
462 #define NSS_BACKEND(name, reg) \
463 ns_mtab	*reg(unsigned int *, nss_module_unregister_fn *);
464 #include "nss_backends.h"
465 #undef NSS_BACKEND
466 
467 static void
nss_load_builtin_modules(void)468 nss_load_builtin_modules(void)
469 {
470 #define NSS_BACKEND(name, reg) nss_load_module(#name, reg);
471 #include "nss_backends.h"
472 #undef NSS_BACKEND
473 }
474 
475 
476 /* Load a built-in or dynamically linked module.  If the `reg_fn'
477  * argument is non-NULL, assume a built-in module and use reg_fn to
478  * register it.  Otherwise, search for a dynamic NSS module.
479  */
480 static void
nss_load_module(const char * source,nss_module_register_fn reg_fn)481 nss_load_module(const char *source, nss_module_register_fn reg_fn)
482 {
483 	char		 buf[PATH_MAX];
484 	ns_mod		 mod;
485 	nss_module_register_fn fn;
486 
487 	memset(&mod, 0, sizeof(mod));
488 	mod.name = strdup(source);
489 	if (mod.name == NULL) {
490 		nss_log_simple(LOG_ERR, "memory allocation failure");
491 		return;
492 	}
493 	if (reg_fn != NULL) {
494 		/* The placeholder is required, as a NULL handle
495 		 * represents an invalid module.
496 		 */
497 		mod.handle = nss_builtin_handle;
498 		fn = reg_fn;
499 	} else if (!is_dynamic()) {
500 		goto fin;
501 	} else if (strcmp(source, NSSRC_CACHE) == 0 ||
502 	    strcmp(source, NSSRC_COMPAT) == 0 ||
503 	    strcmp(source, NSSRC_DB) == 0 ||
504 	    strcmp(source, NSSRC_DNS) == 0 ||
505 	    strcmp(source, NSSRC_FILES) == 0 ||
506 	    strcmp(source, NSSRC_NIS) == 0) {
507 		/*
508 		 * Avoid calling dlopen(3) for built-in modules.
509 		 */
510 		goto fin;
511 	} else {
512 		if (snprintf(buf, sizeof(buf), "nss_%s.so.%d", mod.name,
513 		    NSS_MODULE_INTERFACE_VERSION) >= (int)sizeof(buf))
514 			goto fin;
515 		mod.handle = libc_dlopen(buf, RTLD_LOCAL|RTLD_LAZY);
516 		if (mod.handle == NULL) {
517 #ifdef _NSS_DEBUG
518 			/* This gets pretty annoying since the built-in
519 			 * sources aren't modules yet.
520 			 */
521 			nss_log(LOG_DEBUG, "%s, %s", mod.name, dlerror());
522 #endif
523 			goto fin;
524 		}
525 		fn = (nss_module_register_fn)dlfunc(mod.handle,
526 		    "nss_module_register");
527 		if (fn == NULL) {
528 			(void)dlclose(mod.handle);
529 			mod.handle = NULL;
530 			nss_log(LOG_ERR, "%s, %s", mod.name, dlerror());
531 			goto fin;
532 		}
533 	}
534 	mod.mtab = fn(mod.name, &mod.mtabsize, &mod.unregister);
535 	if (mod.mtab == NULL || mod.mtabsize == 0) {
536 		if (mod.handle != nss_builtin_handle)
537 			(void)dlclose(mod.handle);
538 		mod.handle = NULL;
539 		nss_log(LOG_ERR, "%s, registration failed", mod.name);
540 		goto fin;
541 	}
542 	if (mod.mtabsize > 1)
543 		qsort(mod.mtab, mod.mtabsize, sizeof(mod.mtab[0]),
544 		    mtab_compare);
545 fin:
546 	_nsmod = vector_append(&mod, _nsmod, &_nsmodsize, sizeof(*_nsmod));
547 	vector_sort(_nsmod, _nsmodsize, sizeof(*_nsmod), string_compare);
548 }
549 
550 static int exiting = 0;
551 
552 static void
ns_mod_free(ns_mod * mod)553 ns_mod_free(ns_mod *mod)
554 {
555 
556 	free(mod->name);
557 	if (mod->handle == NULL)
558 		return;
559 	if (mod->unregister != NULL)
560 		mod->unregister(mod->mtab, mod->mtabsize);
561 	if (mod->handle != nss_builtin_handle && !exiting)
562 		(void)dlclose(mod->handle);
563 }
564 
565 /*
566  * Cleanup
567  */
568 static void
nss_atexit(void)569 nss_atexit(void)
570 {
571 	int isthreaded;
572 
573 	exiting = 1;
574 	isthreaded = __isthreaded;
575 	if (isthreaded)
576 		(void)_pthread_rwlock_wrlock(&nss_lock);
577 	VECTOR_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
578 	    (vector_free_elem)ns_dbt_free);
579 	VECTOR_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
580 	    (vector_free_elem)ns_mod_free);
581 	if (isthreaded)
582 		(void)_pthread_rwlock_unlock(&nss_lock);
583 }
584 
585 /*
586  * Finally, the actual implementation.
587  */
588 static nss_method
nss_method_lookup(const char * source,const char * database,const char * method,const ns_dtab disp_tab[],void ** mdata)589 nss_method_lookup(const char *source, const char *database,
590     const char *method, const ns_dtab disp_tab[], void **mdata)
591 {
592 	ns_mod	*mod;
593 	ns_mtab	*match, key;
594 	int	 i;
595 
596 	if (disp_tab != NULL)
597 		for (i = 0; disp_tab[i].src != NULL; i++)
598 			if (strcasecmp(source, disp_tab[i].src) == 0) {
599 				*mdata = disp_tab[i].mdata;
600 				return (disp_tab[i].method);
601 			}
602 	mod = vector_search(&source, _nsmod, _nsmodsize, sizeof(*_nsmod),
603 	    string_compare);
604 	if (mod != NULL && mod->handle != NULL) {
605 		key.database = database;
606 		key.name = method;
607 		match = bsearch(&key, mod->mtab, mod->mtabsize,
608 		    sizeof(mod->mtab[0]), mtab_compare);
609 		if (match != NULL) {
610 			*mdata = match->mdata;
611 			return (match->method);
612 		}
613 	}
614 
615 	*mdata = NULL;
616 	return (NULL);
617 }
618 
619 static void
fb_endstate(void * p)620 fb_endstate(void *p)
621 {
622 	free(p);
623 }
624 
625 __weak_reference(_nsdispatch, nsdispatch);
626 
627 int
_nsdispatch(void * retval,const ns_dtab disp_tab[],const char * database,const char * method_name,const ns_src defaults[],...)628 _nsdispatch(void *retval, const ns_dtab disp_tab[], const char *database,
629 	    const char *method_name, const ns_src defaults[], ...)
630 {
631 	va_list		 ap;
632 	const ns_dbt	*dbt;
633 	const ns_src	*srclist;
634 	nss_method	 method, fb_method;
635 	void		*mdata;
636 	int		 isthreaded, serrno, i, result, srclistsize;
637 	struct fb_state	*st;
638 	int		 saved_depth;
639 
640 #ifdef NS_CACHING
641 	nss_cache_data	 cache_data;
642 	nss_cache_data	*cache_data_p;
643 	int		 cache_flag;
644 #endif
645 
646 	dbt = NULL;
647 	fb_method = NULL;
648 
649 	isthreaded = __isthreaded;
650 	serrno = errno;
651 	if (isthreaded) {
652 		result = _pthread_rwlock_rdlock(&nss_lock);
653 		if (result != 0) {
654 			result = NS_UNAVAIL;
655 			goto fin;
656 		}
657 	}
658 
659 	result = fb_getstate(&st);
660 	if (result != 0) {
661 		result = NS_UNAVAIL;
662 		goto fin;
663 	}
664 
665 	result = nss_configure();
666 	if (result != 0) {
667 		result = NS_UNAVAIL;
668 		goto fin;
669 	}
670 	++st->dispatch_depth;
671 	if (st->dispatch_depth > st->fallback_depth) {
672 		dbt = vector_search(&database, _nsmap, _nsmapsize, sizeof(*_nsmap),
673 		    string_compare);
674 		fb_method = nss_method_lookup(NSSRC_FALLBACK, database,
675 		    method_name, disp_tab, &mdata);
676 	}
677 
678 	if (dbt != NULL) {
679 		srclist = dbt->srclist;
680 		srclistsize = dbt->srclistsize;
681 	} else {
682 		srclist = defaults;
683 		srclistsize = 0;
684 		while (srclist[srclistsize].name != NULL)
685 			srclistsize++;
686 	}
687 
688 #ifdef NS_CACHING
689 	cache_data_p = NULL;
690 	cache_flag = 0;
691 #endif
692 	for (i = 0; i < srclistsize; i++) {
693 		result = NS_NOTFOUND;
694 		method = nss_method_lookup(srclist[i].name, database,
695 		    method_name, disp_tab, &mdata);
696 
697 		if (method != NULL) {
698 #ifdef NS_CACHING
699 			if (strcmp(srclist[i].name, NSSRC_CACHE) == 0 &&
700 			    nss_cache_cycle_prevention_func == NULL) {
701 #ifdef NS_STRICT_LIBC_EID_CHECKING
702 				if (issetugid() != 0)
703 					continue;
704 #endif
705 				cache_flag = 1;
706 
707 				memset(&cache_data, 0, sizeof(nss_cache_data));
708 				cache_data.info = (nss_cache_info const *)mdata;
709 				cache_data_p = &cache_data;
710 
711 				va_start(ap, defaults);
712 				if (cache_data.info->id_func != NULL)
713 					result = __nss_common_cache_read(retval,
714 					    cache_data_p, ap);
715 				else if (cache_data.info->marshal_func != NULL)
716 					result = __nss_mp_cache_read(retval,
717 					    cache_data_p, ap);
718 				else
719 					result = __nss_mp_cache_end(retval,
720 					    cache_data_p, ap);
721 				va_end(ap);
722 			} else {
723 				cache_flag = 0;
724 				errno = 0;
725 				va_start(ap, defaults);
726 				result = method(retval, mdata, ap);
727 				va_end(ap);
728 			}
729 #else /* NS_CACHING */
730 			errno = 0;
731 			va_start(ap, defaults);
732 			result = method(retval, mdata, ap);
733 			va_end(ap);
734 #endif /* NS_CACHING */
735 
736 			if (result & (srclist[i].flags))
737 				break;
738 		} else {
739 			if (fb_method != NULL) {
740 				saved_depth = st->fallback_depth;
741 				st->fallback_depth = st->dispatch_depth + 1;
742 				va_start(ap, defaults);
743 				result = fb_method(retval,
744 				    (void *)srclist[i].name, ap);
745 				va_end(ap);
746 				st->fallback_depth = saved_depth;
747 			} else
748 				nss_log(LOG_DEBUG, "%s, %s, %s, not found, "
749 				    "and no fallback provided",
750 				    srclist[i].name, database, method_name);
751 		}
752 	}
753 
754 #ifdef NS_CACHING
755 	if (cache_data_p != NULL &&
756 	    (result & (NS_NOTFOUND | NS_SUCCESS)) && cache_flag == 0) {
757 		va_start(ap, defaults);
758 		if (result == NS_SUCCESS) {
759 			if (cache_data.info->id_func != NULL)
760 				__nss_common_cache_write(retval, cache_data_p,
761 				    ap);
762 			else if (cache_data.info->marshal_func != NULL)
763 				__nss_mp_cache_write(retval, cache_data_p, ap);
764 		} else if (result == NS_NOTFOUND) {
765 			if (cache_data.info->id_func == NULL) {
766 				if (cache_data.info->marshal_func != NULL)
767 					__nss_mp_cache_write_submit(retval,
768 					    cache_data_p, ap);
769 			} else
770 				__nss_common_cache_write_negative(cache_data_p);
771 		}
772 		va_end(ap);
773 	}
774 #endif /* NS_CACHING */
775 
776 	if (isthreaded)
777 		(void)_pthread_rwlock_unlock(&nss_lock);
778 	--st->dispatch_depth;
779 fin:
780 	errno = serrno;
781 	return (result);
782 }
783