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# ifdef NEED__RES
238 __resolv_context_put (res_ctx);
239# endif
240 return errno;
241 case 1:
242#ifdef NEED_H_ERRNO
243 any_service = true;
244#endif
245 goto done;
246 }
247#endif
248
249#ifdef USE_NSCD
250 if (NOT_USENSCD_NAME > 0 && ++NOT_USENSCD_NAME > NSS_NSCD_RETRY)
251 NOT_USENSCD_NAME = 0;
252
253 if (!NOT_USENSCD_NAME
254 && !__nss_database_custom[CONCAT2 (NSS_DBSIDX_, DATABASE_NAME)])
255 {
256 nscd_status = NSCD_NAME (ADD_VARIABLES, resbuf, buffer, buflen, result
257 H_ERRNO_VAR);
258 if (nscd_status >= 0)
259 {
260# ifdef NEED__RES
261 __resolv_context_put (res_ctx);
262# endif
263 return nscd_status;
264 }
265 }
266#endif
267
268 if (! startp_initialized)
269 {
270 no_more = DB_LOOKUP_FCT (&nip, REENTRANT_NAME_STRING,
271 REENTRANT2_NAME_STRING, &fct.ptr);
272 if (no_more)
273 {
274 void *tmp_ptr = (service_user *) -1l;
275#ifdef PTR_MANGLE
276 PTR_MANGLE (tmp_ptr);
277#endif
278 startp = tmp_ptr;
279 }
280 else
281 {
282 void *tmp_ptr = fct.l;
283#ifdef PTR_MANGLE
284 PTR_MANGLE (tmp_ptr);
285#endif
286 start_fct = tmp_ptr;
287 tmp_ptr = nip;
288#ifdef PTR_MANGLE
289 PTR_MANGLE (tmp_ptr);
290#endif
291 startp = tmp_ptr;
292 }
293
294 /* Make sure start_fct and startp are written before
295 startp_initialized. */
296 atomic_write_barrier ();
297 startp_initialized = true;
298 }
299 else
300 {
301 fct.l = start_fct;
302 nip = startp;
303#ifdef PTR_DEMANGLE
304 PTR_DEMANGLE (fct.l);
305 PTR_DEMANGLE (nip);
306#endif
307 no_more = nip == (service_user *) -1l;
308 }
309
310 while (no_more == 0)
311 {
312#ifdef NEED_H_ERRNO
313 any_service = true;
314#endif
315
316 status = DL_CALL_FCT (fct.l, (ADD_VARIABLES, resbuf, buffer, buflen,
317 &errno H_ERRNO_VAR EXTRA_VARIABLES));
318
319 /* The status is NSS_STATUS_TRYAGAIN and errno is ERANGE the
320 provided buffer is too small. In this case we should give
321 the user the possibility to enlarge the buffer and we should
322 not simply go on with the next service (even if the TRYAGAIN
323 action tells us so). */
324 if (status == NSS_STATUS_TRYAGAIN
325#ifdef NEED_H_ERRNO
326 && *h_errnop == NETDB_INTERNAL
327#endif
328 && errno == ERANGE)
329 break;
330
331 if (do_merge)
332 {
333
334 if (status == NSS_STATUS_SUCCESS)
335 {
336 /* The previous loop saved a buffer for merging.
337 Perform the merge now. */
338 err = MERGE_FN (&mergegrp, mergebuf, endptr, buflen, resbuf,
339 buffer);
340 CHECK_MERGE (err,status);
341 do_merge = 0;
342 }
343 else
344 {
345 /* If the result wasn't SUCCESS, copy the saved buffer back
346 into the result buffer and set the status back to
347 NSS_STATUS_SUCCESS to match the previous pass through the
348 loop.
349 * If the next action is CONTINUE, it will overwrite the value
350 currently in the buffer and return the new value.
351 * If the next action is RETURN, we'll return the previously-
352 acquired values.
353 * If the next action is MERGE, then it will be added to the
354 buffer saved from the previous source. */
355 err = DEEPCOPY_FN (mergegrp, buflen, resbuf, buffer, NULL);
356 CHECK_MERGE (err, status);
357 status = NSS_STATUS_SUCCESS;
358 }
359 }
360
361 /* If we were are configured to merge this value with the next one,
362 save the current value of the group struct. */
363 if (nss_next_action (nip, status) == NSS_ACTION_MERGE
364 && status == NSS_STATUS_SUCCESS)
365 {
366 /* Copy the current values into a buffer to be merged with the next
367 set of retrieved values. */
368 if (mergebuf == NULL)
369 {
370 /* Only allocate once and reuse it for as many merges as we need
371 to perform. */
372 mergebuf = malloc (buflen);
373 if (mergebuf == NULL)
374 {
375 __set_errno (ENOMEM);
376 status = NSS_STATUS_UNAVAIL;
377 break;
378 }
379 }
380
381 err = DEEPCOPY_FN (*resbuf, buflen, &mergegrp, mergebuf, &endptr);
382 CHECK_MERGE (err, status);
383 do_merge = 1;
384 }
385
386 no_more = __nss_next2 (&nip, REENTRANT_NAME_STRING,
387 REENTRANT2_NAME_STRING, &fct.ptr, status, 0);
388 }
389 free (mergebuf);
390 mergebuf = NULL;
391
392#ifdef HANDLE_DIGITS_DOTS
393done:
394#endif
395 *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
396#ifdef NEED_H_ERRNO
397 if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)
398 /* This happens when we weren't able to use a service for reasons other
399 than the module not being found. In such a case, we'd want to tell the
400 caller that errno has the real reason for failure. */
401 *h_errnop = NETDB_INTERNAL;
402 else if (status != NSS_STATUS_SUCCESS && !any_service)
403 /* We were not able to use any service. */
404 *h_errnop = NO_RECOVERY;
405#endif
406#ifdef POSTPROCESS
407 POSTPROCESS;
408#endif
409
410#ifdef NEED__RES
411 /* This has to happen late because the POSTPROCESS stage above might
412 need the resolver context. */
413 __resolv_context_put (res_ctx);
414#endif /* NEED__RES */
415
416 int res;
417 if (status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND)
418 res = 0;
419 /* Don't pass back ERANGE if this is not for a too-small buffer. */
420 else if (errno == ERANGE && status != NSS_STATUS_TRYAGAIN)
421 res = EINVAL;
422#ifdef NEED_H_ERRNO
423 /* These functions only set errno if h_errno is NETDB_INTERNAL. */
424 else if (status == NSS_STATUS_TRYAGAIN && *h_errnop != NETDB_INTERNAL)
425 res = EAGAIN;
426#endif
427 else
428 return errno;
429
430 __set_errno (res);
431 return res;
432}
433
434
435#ifdef NO_COMPAT_NEEDED
436strong_alias (INTERNAL (REENTRANT_NAME), REENTRANT_NAME);
437#elif !defined FUNCTION2_NAME
438# include <shlib-compat.h>
439# if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1_2)
440# define OLD(name) OLD1 (name)
441# define OLD1(name) __old_##name
442
443int
444attribute_compat_text_section
445OLD (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
446 size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM)
447{
448 int ret = INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, resbuf, buffer,
449 buflen, result H_ERRNO_VAR);
450
451 if (ret != 0 || result == NULL)
452 ret = -1;
453
454 return ret;
455}
456
457# define do_symbol_version(real, name, version) \
458 compat_symbol (libc, real, name, version)
459do_symbol_version (OLD (REENTRANT_NAME), REENTRANT_NAME, GLIBC_2_0);
460# endif
461
462/* As INTERNAL (REENTRANT_NAME) may be hidden, we need an alias
463 in between so that the REENTRANT_NAME@@GLIBC_2.1.2 is not
464 hidden too. */
465strong_alias (INTERNAL (REENTRANT_NAME), NEW (REENTRANT_NAME));
466
467# define do_default_symbol_version(real, name, version) \
468 versioned_symbol (libc, real, name, version)
469do_default_symbol_version (NEW (REENTRANT_NAME),
470 REENTRANT_NAME, GLIBC_2_1_2);
471#endif
472
473nss_interface_function (REENTRANT_NAME)
474