1/* Copyright (C) 1996-2021 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 <https://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 (nss_action_list *nip, const char *name,
183 const char *name2, void **fctp);
184libc_hidden_proto (DB_LOOKUP_FCT)
185
186
187int
188INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
189 size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM
190 EXTRA_PARAMS)
191{
192 nss_action_list nip;
193 int do_merge = 0;
194 LOOKUP_TYPE mergegrp;
195 char *mergebuf = NULL;
196 char *endptr = NULL;
197 union
198 {
199 lookup_function l;
200 void *ptr;
201 } fct;
202 int no_more, err;
203 enum nss_status status = NSS_STATUS_UNAVAIL;
204#ifdef USE_NSCD
205 int nscd_status;
206#endif
207#ifdef NEED_H_ERRNO
208 bool any_service = false;
209#endif
210
211#ifdef NEED__RES
212 /* The HANDLE_DIGITS_DOTS case below already needs the resolver
213 configuration, so this has to happen early. */
214 struct resolv_context *res_ctx = __resolv_context_get ();
215 if (res_ctx == NULL)
216 {
217 *h_errnop = NETDB_INTERNAL;
218 *result = NULL;
219 return errno;
220 }
221#endif /* NEED__RES */
222
223#ifdef PREPROCESS
224 PREPROCESS;
225#endif
226
227
228#ifdef HANDLE_DIGITS_DOTS
229 switch (__nss_hostname_digits_dots (name, resbuf, &buffer, NULL,
230 buflen, result, &status, AF_VAL,
231 H_ERRNO_VAR_P))
232 {
233 case -1:
234# ifdef NEED__RES
235 __resolv_context_put (res_ctx);
236# endif
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 {
257# ifdef NEED__RES
258 __resolv_context_put (res_ctx);
259# endif
260 return nscd_status;
261 }
262 }
263#endif
264
265 no_more = DB_LOOKUP_FCT (&nip, REENTRANT_NAME_STRING,
266 REENTRANT2_NAME_STRING, &fct.ptr);
267
268 while (no_more == 0)
269 {
270#ifdef NEED_H_ERRNO
271 any_service = true;
272#endif
273
274 status = DL_CALL_FCT (fct.l, (ADD_VARIABLES, resbuf, buffer, buflen,
275 &errno H_ERRNO_VAR EXTRA_VARIABLES));
276
277 /* The status is NSS_STATUS_TRYAGAIN and errno is ERANGE the
278 provided buffer is too small. In this case we should give
279 the user the possibility to enlarge the buffer and we should
280 not simply go on with the next service (even if the TRYAGAIN
281 action tells us so). */
282 if (status == NSS_STATUS_TRYAGAIN
283#ifdef NEED_H_ERRNO
284 && *h_errnop == NETDB_INTERNAL
285#endif
286 && errno == ERANGE)
287 break;
288
289 if (do_merge)
290 {
291
292 if (status == NSS_STATUS_SUCCESS)
293 {
294 /* The previous loop saved a buffer for merging.
295 Perform the merge now. */
296 err = MERGE_FN (&mergegrp, mergebuf, endptr, buflen, resbuf,
297 buffer);
298 CHECK_MERGE (err,status);
299 do_merge = 0;
300 }
301 else
302 {
303 /* If the result wasn't SUCCESS, copy the saved buffer back
304 into the result buffer and set the status back to
305 NSS_STATUS_SUCCESS to match the previous pass through the
306 loop.
307 * If the next action is CONTINUE, it will overwrite the value
308 currently in the buffer and return the new value.
309 * If the next action is RETURN, we'll return the previously-
310 acquired values.
311 * If the next action is MERGE, then it will be added to the
312 buffer saved from the previous source. */
313 err = DEEPCOPY_FN (mergegrp, buflen, resbuf, buffer, NULL);
314 CHECK_MERGE (err, status);
315 status = NSS_STATUS_SUCCESS;
316 }
317 }
318
319 /* If we were are configured to merge this value with the next one,
320 save the current value of the group struct. */
321 if (nss_next_action (nip, status) == NSS_ACTION_MERGE
322 && status == NSS_STATUS_SUCCESS)
323 {
324 /* Copy the current values into a buffer to be merged with the next
325 set of retrieved values. */
326 if (mergebuf == NULL)
327 {
328 /* Only allocate once and reuse it for as many merges as we need
329 to perform. */
330 mergebuf = malloc (buflen);
331 if (mergebuf == NULL)
332 {
333 __set_errno (ENOMEM);
334 status = NSS_STATUS_UNAVAIL;
335 break;
336 }
337 }
338
339 err = DEEPCOPY_FN (*resbuf, buflen, &mergegrp, mergebuf, &endptr);
340 CHECK_MERGE (err, status);
341 do_merge = 1;
342 }
343
344 no_more = __nss_next2 (&nip, REENTRANT_NAME_STRING,
345 REENTRANT2_NAME_STRING, &fct.ptr, status, 0);
346 }
347 free (mergebuf);
348 mergebuf = NULL;
349
350#ifdef HANDLE_DIGITS_DOTS
351done:
352#endif
353 *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
354#ifdef NEED_H_ERRNO
355 if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)
356 /* This happens when we weren't able to use a service for reasons other
357 than the module not being found. In such a case, we'd want to tell the
358 caller that errno has the real reason for failure. */
359 *h_errnop = NETDB_INTERNAL;
360 else if (status != NSS_STATUS_SUCCESS && !any_service)
361 /* We were not able to use any service. */
362 *h_errnop = NO_RECOVERY;
363#endif
364#ifdef POSTPROCESS
365 POSTPROCESS;
366#endif
367
368#ifdef NEED__RES
369 /* This has to happen late because the POSTPROCESS stage above might
370 need the resolver context. */
371 __resolv_context_put (res_ctx);
372#endif /* NEED__RES */
373
374 int res;
375 if (status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND)
376 res = 0;
377 /* Don't pass back ERANGE if this is not for a too-small buffer. */
378 else if (errno == ERANGE && status != NSS_STATUS_TRYAGAIN)
379 res = EINVAL;
380#ifdef NEED_H_ERRNO
381 /* These functions only set errno if h_errno is NETDB_INTERNAL. */
382 else if (status == NSS_STATUS_TRYAGAIN && *h_errnop != NETDB_INTERNAL)
383 res = EAGAIN;
384#endif
385 else
386 return errno;
387
388 __set_errno (res);
389 return res;
390}
391
392
393#ifdef NO_COMPAT_NEEDED
394strong_alias (INTERNAL (REENTRANT_NAME), REENTRANT_NAME);
395#elif !defined FUNCTION2_NAME
396# include <shlib-compat.h>
397# if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1_2)
398# define OLD(name) OLD1 (name)
399# define OLD1(name) __old_##name
400
401int
402attribute_compat_text_section
403OLD (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
404 size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM)
405{
406 int ret = INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, resbuf, buffer,
407 buflen, result H_ERRNO_VAR);
408
409 if (ret != 0 || result == NULL)
410 ret = -1;
411
412 return ret;
413}
414
415# define do_symbol_version(real, name, version) \
416 compat_symbol (libc, real, name, version)
417do_symbol_version (OLD (REENTRANT_NAME), REENTRANT_NAME, GLIBC_2_0);
418# endif
419
420/* As INTERNAL (REENTRANT_NAME) may be hidden, we need an alias
421 in between so that the REENTRANT_NAME@@GLIBC_2.1.2 is not
422 hidden too. */
423strong_alias (INTERNAL (REENTRANT_NAME), NEW (REENTRANT_NAME));
424
425# define do_default_symbol_version(real, name, version) \
426 versioned_symbol (libc, real, name, version)
427do_default_symbol_version (NEW (REENTRANT_NAME),
428 REENTRANT_NAME, GLIBC_2_1_2);
429#endif
430
431nss_interface_function (REENTRANT_NAME)
432