1/* Copyright (C) 1996-2017 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include <assert.h>
20#include <atomic.h>
21#include <errno.h>
22#include <stdbool.h>
23#include "nsswitch.h"
24#include "sysdep.h"
25#ifdef USE_NSCD
26# include <nscd/nscd_proto.h>
27#endif
28#ifdef NEED__RES
29# include <resolv/resolv_context.h>
30#endif
31/*******************************************************************\
32|* Here we assume several symbols to be defined: *|
33|* *|
34|* LOOKUP_TYPE - the return type of the function *|
35|* *|
36|* FUNCTION_NAME - name of the non-reentrant function *|
37|* *|
38|* DATABASE_NAME - name of the database the function accesses *|
39|* (e.g., host, services, ...) *|
40|* *|
41|* ADD_PARAMS - additional parameters, can vary in number *|
42|* *|
43|* ADD_VARIABLES - names of additional parameters *|
44|* *|
45|* Optionally the following vars can be defined: *|
46|* *|
47|* EXTRA_PARAMS - optional parameters, can vary in number *|
48|* *|
49|* EXTRA_VARIABLES - names of optional parameter *|
50|* *|
51|* FUNCTION2_NAME - alternative name of the non-reentrant function *|
52|* *|
53|* NEED_H_ERRNO - an extra parameter will be passed to point to *|
54|* the global `h_errno' variable. *|
55|* *|
56|* NEED__RES - obtain a struct resolv_context resolver context *|
57|* *|
58|* PREPROCESS - code run before anything else *|
59|* *|
60|* POSTPROCESS - code run after the lookup *|
61|* *|
62\*******************************************************************/
63
64/* To make the real sources a bit prettier. */
65#define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
66#ifdef FUNCTION2_NAME
67# define REENTRANT2_NAME APPEND_R (FUNCTION2_NAME)
68#else
69# define REENTRANT2_NAME NULL
70#endif
71#define APPEND_R(name) APPEND_R1 (name)
72#define APPEND_R1(name) name##_r
73#define INTERNAL(name) INTERNAL1 (name)
74#define INTERNAL1(name) __##name
75#define NEW(name) NEW1 (name)
76#define NEW1(name) __new_##name
77
78#ifdef USE_NSCD
79# define NSCD_NAME ADD_NSCD (REENTRANT_NAME)
80# define ADD_NSCD(name) ADD_NSCD1 (name)
81# define ADD_NSCD1(name) __nscd_##name
82# define NOT_USENSCD_NAME ADD_NOT_NSCDUSE (DATABASE_NAME)
83# define ADD_NOT_NSCDUSE(name) ADD_NOT_NSCDUSE1 (name)
84# define ADD_NOT_NSCDUSE1(name) __nss_not_use_nscd_##name
85# define CONCAT2(arg1, arg2) CONCAT2_2 (arg1, arg2)
86# define CONCAT2_2(arg1, arg2) arg1##arg2
87#endif
88
89#define FUNCTION_NAME_STRING STRINGIZE (FUNCTION_NAME)
90#define REENTRANT_NAME_STRING STRINGIZE (REENTRANT_NAME)
91#ifdef FUNCTION2_NAME
92# define REENTRANT2_NAME_STRING STRINGIZE (REENTRANT2_NAME)
93#else
94# define REENTRANT2_NAME_STRING NULL
95#endif
96#define DATABASE_NAME_STRING STRINGIZE (DATABASE_NAME)
97#define STRINGIZE(name) STRINGIZE1 (name)
98#define STRINGIZE1(name) #name
99
100#ifndef DB_LOOKUP_FCT
101# define DB_LOOKUP_FCT CONCAT3_1 (__nss_, DATABASE_NAME, _lookup2)
102# define CONCAT3_1(Pre, Name, Post) CONCAT3_2 (Pre, Name, Post)
103# define CONCAT3_2(Pre, Name, Post) Pre##Name##Post
104#endif
105
106/* Sometimes we need to store error codes in the `h_errno' variable. */
107#ifdef NEED_H_ERRNO
108# define H_ERRNO_PARM , int *h_errnop
109# define H_ERRNO_VAR , h_errnop
110# define H_ERRNO_VAR_P h_errnop
111#else
112# define H_ERRNO_PARM
113# define H_ERRNO_VAR
114# define H_ERRNO_VAR_P NULL
115#endif
116
117#ifndef EXTRA_PARAMS
118# define EXTRA_PARAMS
119#endif
120#ifndef EXTRA_VARIABLES
121# define EXTRA_VARIABLES
122#endif
123
124#ifdef HAVE_AF
125# define AF_VAL af
126#else
127# define AF_VAL AF_INET
128#endif
129
130
131/* Set defaults for merge functions that haven't been defined. */
132#ifndef DEEPCOPY_FN
133static inline int
134__copy_einval (LOOKUP_TYPE a,
135 const size_t b,
136 LOOKUP_TYPE *c,
137 char *d,
138 char **e)
139{
140 return EINVAL;
141}
142# define DEEPCOPY_FN __copy_einval
143#endif
144
145#ifndef MERGE_FN
146static inline int
147__merge_einval (LOOKUP_TYPE *a,
148 char *b,
149 char *c,
150 size_t d,
151 LOOKUP_TYPE *e,
152 char *f)
153{
154 return EINVAL;
155}
156# define MERGE_FN __merge_einval
157#endif
158
159#define CHECK_MERGE(err, status) \
160 ({ \
161 do \
162 { \
163 if (err) \
164 { \
165 __set_errno (err); \
166 if (err == ERANGE) \
167 status = NSS_STATUS_TRYAGAIN; \
168 else \
169 status = NSS_STATUS_UNAVAIL; \
170 break; \
171 } \
172 } \
173 while (0); \
174 })
175
176/* Type of the lookup function we need here. */
177typedef enum nss_status (*lookup_function) (ADD_PARAMS, LOOKUP_TYPE *, char *,
178 size_t, int * H_ERRNO_PARM
179 EXTRA_PARAMS);
180
181/* The lookup function for the first entry of this service. */
182extern int DB_LOOKUP_FCT (service_user **nip, const char *name,
183 const char *name2, void **fctp)
184 internal_function;
185libc_hidden_proto (DB_LOOKUP_FCT)
186
187
188int
189INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
190 size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM
191 EXTRA_PARAMS)
192{
193 static bool startp_initialized;
194 static service_user *startp;
195 static lookup_function start_fct;
196 service_user *nip;
197 int do_merge = 0;
198 LOOKUP_TYPE mergegrp;
199 char *mergebuf = NULL;
200 char *endptr = NULL;
201 union
202 {
203 lookup_function l;
204 void *ptr;
205 } fct;
206 int no_more, err;
207 enum nss_status status = NSS_STATUS_UNAVAIL;
208#ifdef USE_NSCD
209 int nscd_status;
210#endif
211#ifdef NEED_H_ERRNO
212 bool any_service = false;
213#endif
214
215#ifdef NEED__RES
216 /* The HANDLE_DIGITS_DOTS case below already needs the resolver
217 configuration, so this has to happen early. */
218 struct resolv_context *res_ctx = __resolv_context_get ();
219 if (res_ctx == NULL)
220 {
221 *h_errnop = NETDB_INTERNAL;
222 *result = NULL;
223 return errno;
224 }
225#endif /* NEED__RES */
226
227#ifdef PREPROCESS
228 PREPROCESS;
229#endif
230
231#ifdef HANDLE_DIGITS_DOTS
232 switch (__nss_hostname_digits_dots (name, resbuf, &buffer, NULL,
233 buflen, result, &status, AF_VAL,
234 H_ERRNO_VAR_P))
235 {
236 case -1:
237 return errno;
238 case 1:
239#ifdef NEED_H_ERRNO
240 any_service = true;
241#endif
242 goto done;
243 }
244#endif
245
246#ifdef USE_NSCD
247 if (NOT_USENSCD_NAME > 0 && ++NOT_USENSCD_NAME > NSS_NSCD_RETRY)
248 NOT_USENSCD_NAME = 0;
249
250 if (!NOT_USENSCD_NAME
251 && !__nss_database_custom[CONCAT2 (NSS_DBSIDX_, DATABASE_NAME)])
252 {
253 nscd_status = NSCD_NAME (ADD_VARIABLES, resbuf, buffer, buflen, result
254 H_ERRNO_VAR);
255 if (nscd_status >= 0)
256 return nscd_status;
257 }
258#endif
259
260 if (! startp_initialized)
261 {
262 no_more = DB_LOOKUP_FCT (&nip, REENTRANT_NAME_STRING,
263 REENTRANT2_NAME_STRING, &fct.ptr);
264 if (no_more)
265 {
266 void *tmp_ptr = (service_user *) -1l;
267#ifdef PTR_MANGLE
268 PTR_MANGLE (tmp_ptr);
269#endif
270 startp = tmp_ptr;
271 }
272 else
273 {
274 void *tmp_ptr = fct.l;
275#ifdef PTR_MANGLE
276 PTR_MANGLE (tmp_ptr);
277#endif
278 start_fct = tmp_ptr;
279 tmp_ptr = nip;
280#ifdef PTR_MANGLE
281 PTR_MANGLE (tmp_ptr);
282#endif
283 startp = tmp_ptr;
284 }
285
286 /* Make sure start_fct and startp are written before
287 startp_initialized. */
288 atomic_write_barrier ();
289 startp_initialized = true;
290 }
291 else
292 {
293 fct.l = start_fct;
294 nip = startp;
295#ifdef PTR_DEMANGLE
296 PTR_DEMANGLE (fct.l);
297 PTR_DEMANGLE (nip);
298#endif
299 no_more = nip == (service_user *) -1l;
300 }
301
302 while (no_more == 0)
303 {
304#ifdef NEED_H_ERRNO
305 any_service = true;
306#endif
307
308 status = DL_CALL_FCT (fct.l, (ADD_VARIABLES, resbuf, buffer, buflen,
309 &errno H_ERRNO_VAR EXTRA_VARIABLES));
310
311 /* The status is NSS_STATUS_TRYAGAIN and errno is ERANGE the
312 provided buffer is too small. In this case we should give
313 the user the possibility to enlarge the buffer and we should
314 not simply go on with the next service (even if the TRYAGAIN
315 action tells us so). */
316 if (status == NSS_STATUS_TRYAGAIN
317#ifdef NEED_H_ERRNO
318 && *h_errnop == NETDB_INTERNAL
319#endif
320 && errno == ERANGE)
321 break;
322
323 if (do_merge)
324 {
325
326 if (status == NSS_STATUS_SUCCESS)
327 {
328 /* The previous loop saved a buffer for merging.
329 Perform the merge now. */
330 err = MERGE_FN (&mergegrp, mergebuf, endptr, buflen, resbuf,
331 buffer);
332 CHECK_MERGE (err,status);
333 do_merge = 0;
334 }
335 else
336 {
337 /* If the result wasn't SUCCESS, copy the saved buffer back
338 into the result buffer and set the status back to
339 NSS_STATUS_SUCCESS to match the previous pass through the
340 loop.
341 * If the next action is CONTINUE, it will overwrite the value
342 currently in the buffer and return the new value.
343 * If the next action is RETURN, we'll return the previously-
344 acquired values.
345 * If the next action is MERGE, then it will be added to the
346 buffer saved from the previous source. */
347 err = DEEPCOPY_FN (mergegrp, buflen, resbuf, buffer, NULL);
348 CHECK_MERGE (err, status);
349 status = NSS_STATUS_SUCCESS;
350 }
351 }
352
353 /* If we were are configured to merge this value with the next one,
354 save the current value of the group struct. */
355 if (nss_next_action (nip, status) == NSS_ACTION_MERGE
356 && status == NSS_STATUS_SUCCESS)
357 {
358 /* Copy the current values into a buffer to be merged with the next
359 set of retrieved values. */
360 if (mergebuf == NULL)
361 {
362 /* Only allocate once and reuse it for as many merges as we need
363 to perform. */
364 mergebuf = malloc (buflen);
365 if (mergebuf == NULL)
366 {
367 __set_errno (ENOMEM);
368 status = NSS_STATUS_UNAVAIL;
369 break;
370 }
371 }
372
373 err = DEEPCOPY_FN (*resbuf, buflen, &mergegrp, mergebuf, &endptr);
374 CHECK_MERGE (err, status);
375 do_merge = 1;
376 }
377
378 no_more = __nss_next2 (&nip, REENTRANT_NAME_STRING,
379 REENTRANT2_NAME_STRING, &fct.ptr, status, 0);
380 }
381 free (mergebuf);
382 mergebuf = NULL;
383
384#ifdef HANDLE_DIGITS_DOTS
385done:
386#endif
387 *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
388#ifdef NEED_H_ERRNO
389 if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)
390 /* This happens when we weren't able to use a service for reasons other
391 than the module not being found. In such a case, we'd want to tell the
392 caller that errno has the real reason for failure. */
393 *h_errnop = NETDB_INTERNAL;
394 else if (status != NSS_STATUS_SUCCESS && !any_service)
395 /* We were not able to use any service. */
396 *h_errnop = NO_RECOVERY;
397#endif
398#ifdef POSTPROCESS
399 POSTPROCESS;
400#endif
401
402#ifdef NEED__RES
403 /* This has to happen late because the POSTPROCESS stage above might
404 need the resolver context. */
405 __resolv_context_put (res_ctx);
406#endif /* NEED__RES */
407
408 int res;
409 if (status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND)
410 res = 0;
411 /* Don't pass back ERANGE if this is not for a too-small buffer. */
412 else if (errno == ERANGE && status != NSS_STATUS_TRYAGAIN)
413 res = EINVAL;
414#ifdef NEED_H_ERRNO
415 /* These functions only set errno if h_errno is NETDB_INTERNAL. */
416 else if (status == NSS_STATUS_TRYAGAIN && *h_errnop != NETDB_INTERNAL)
417 res = EAGAIN;
418#endif
419 else
420 return errno;
421
422 __set_errno (res);
423 return res;
424}
425
426
427#ifdef NO_COMPAT_NEEDED
428strong_alias (INTERNAL (REENTRANT_NAME), REENTRANT_NAME);
429#elif !defined FUNCTION2_NAME
430# include <shlib-compat.h>
431# if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1_2)
432# define OLD(name) OLD1 (name)
433# define OLD1(name) __old_##name
434
435int
436attribute_compat_text_section
437OLD (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
438 size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM)
439{
440 int ret = INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, resbuf, buffer,
441 buflen, result H_ERRNO_VAR);
442
443 if (ret != 0 || result == NULL)
444 ret = -1;
445
446 return ret;
447}
448
449# define do_symbol_version(real, name, version) \
450 compat_symbol (libc, real, name, version)
451do_symbol_version (OLD (REENTRANT_NAME), REENTRANT_NAME, GLIBC_2_0);
452# endif
453
454/* As INTERNAL (REENTRANT_NAME) may be hidden, we need an alias
455 in between so that the REENTRANT_NAME@@GLIBC_2.1.2 is not
456 hidden too. */
457strong_alias (INTERNAL (REENTRANT_NAME), NEW (REENTRANT_NAME));
458
459# define do_default_symbol_version(real, name, version) \
460 versioned_symbol (libc, real, name, version)
461do_default_symbol_version (NEW (REENTRANT_NAME),
462 REENTRANT_NAME, GLIBC_2_1_2);
463#endif
464
465nss_interface_function (REENTRANT_NAME)
466