1/* Copyright (C) 1996-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <assert.h>
19#include <atomic.h>
20#include <errno.h>
21#include <stdbool.h>
22#include "nsswitch.h"
23#include "sysdep.h"
24#ifdef USE_NSCD
25# include <nscd/nscd_proto.h>
26#endif
27#ifdef NEED__RES
28# include <resolv/resolv_context.h>
29#endif
30/*******************************************************************\
31|* Here we assume several symbols to be defined: *|
32|* *|
33|* LOOKUP_TYPE - the return type of the function *|
34|* *|
35|* FUNCTION_NAME - name of the non-reentrant function *|
36|* *|
37|* DATABASE_NAME - name of the database the function accesses *|
38|* (e.g., host, services, ...) *|
39|* *|
40|* ADD_PARAMS - additional parameters, can vary in number *|
41|* *|
42|* ADD_VARIABLES - names of additional parameters *|
43|* *|
44|* Optionally the following vars can be defined: *|
45|* *|
46|* EXTRA_PARAMS - optional parameters, can vary in number *|
47|* *|
48|* EXTRA_VARIABLES - names of optional parameter *|
49|* *|
50|* FUNCTION2_NAME - alternative name of the non-reentrant function *|
51|* *|
52|* NEED_H_ERRNO - an extra parameter will be passed to point to *|
53|* the global `h_errno' variable. *|
54|* *|
55|* NEED__RES - obtain a struct resolv_context resolver context *|
56|* *|
57|* PREPROCESS - code run before anything else *|
58|* *|
59|* POSTPROCESS - code run after the lookup *|
60|* *|
61\*******************************************************************/
62
63/* To make the real sources a bit prettier. */
64#define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
65#ifdef FUNCTION2_NAME
66# define REENTRANT2_NAME APPEND_R (FUNCTION2_NAME)
67#else
68# define REENTRANT2_NAME NULL
69#endif
70#define APPEND_R(name) APPEND_R1 (name)
71#define APPEND_R1(name) name##_r
72#define INTERNAL(name) INTERNAL1 (name)
73#define INTERNAL1(name) __##name
74#define NEW(name) NEW1 (name)
75#define NEW1(name) __new_##name
76
77#ifdef USE_NSCD
78# define NSCD_NAME ADD_NSCD (REENTRANT_NAME)
79# define ADD_NSCD(name) ADD_NSCD1 (name)
80# define ADD_NSCD1(name) __nscd_##name
81# define NOT_USENSCD_NAME ADD_NOT_NSCDUSE (DATABASE_NAME)
82# define ADD_NOT_NSCDUSE(name) ADD_NOT_NSCDUSE1 (name)
83# define ADD_NOT_NSCDUSE1(name) __nss_not_use_nscd_##name
84# define CONCAT2(arg1, arg2) CONCAT2_2 (arg1, arg2)
85# define CONCAT2_2(arg1, arg2) arg1##arg2
86#endif
87
88#define FUNCTION_NAME_STRING STRINGIZE (FUNCTION_NAME)
89#define REENTRANT_NAME_STRING STRINGIZE (REENTRANT_NAME)
90#ifdef FUNCTION2_NAME
91# define REENTRANT2_NAME_STRING STRINGIZE (REENTRANT2_NAME)
92#else
93# define REENTRANT2_NAME_STRING NULL
94#endif
95#define DATABASE_NAME_STRING STRINGIZE (DATABASE_NAME)
96#define STRINGIZE(name) STRINGIZE1 (name)
97#define STRINGIZE1(name) #name
98
99#ifndef DB_LOOKUP_FCT
100# define DB_LOOKUP_FCT CONCAT3_1 (__nss_, DATABASE_NAME, _lookup2)
101# define CONCAT3_1(Pre, Name, Post) CONCAT3_2 (Pre, Name, Post)
102# define CONCAT3_2(Pre, Name, Post) Pre##Name##Post
103#endif
104
105/* Sometimes we need to store error codes in the `h_errno' variable. */
106#ifdef NEED_H_ERRNO
107# define H_ERRNO_PARM , int *h_errnop
108# define H_ERRNO_VAR , h_errnop
109# define H_ERRNO_VAR_P h_errnop
110#else
111# define H_ERRNO_PARM
112# define H_ERRNO_VAR
113# define H_ERRNO_VAR_P NULL
114#endif
115
116#ifndef EXTRA_PARAMS
117# define EXTRA_PARAMS
118#endif
119#ifndef EXTRA_VARIABLES
120# define EXTRA_VARIABLES
121#endif
122
123#ifdef HAVE_AF
124# define AF_VAL af
125#else
126# define AF_VAL AF_INET
127#endif
128
129
130/* Set defaults for merge functions that haven't been defined. */
131#ifndef DEEPCOPY_FN
132static inline int
133__copy_einval (LOOKUP_TYPE a,
134 const size_t b,
135 LOOKUP_TYPE *c,
136 char *d,
137 char **e)
138{
139 return EINVAL;
140}
141# define DEEPCOPY_FN __copy_einval
142#endif
143
144#ifndef MERGE_FN
145static inline int
146__merge_einval (LOOKUP_TYPE *a,
147 char *b,
148 char *c,
149 size_t d,
150 LOOKUP_TYPE *e,
151 char *f)
152{
153 return EINVAL;
154}
155# define MERGE_FN __merge_einval
156#endif
157
158#define CHECK_MERGE(err, status) \
159 ({ \
160 do \
161 { \
162 if (err) \
163 { \
164 __set_errno (err); \
165 if (err == ERANGE) \
166 status = NSS_STATUS_TRYAGAIN; \
167 else \
168 status = NSS_STATUS_UNAVAIL; \
169 break; \
170 } \
171 } \
172 while (0); \
173 })
174
175/* Type of the lookup function we need here. */
176typedef enum nss_status (*lookup_function) (ADD_PARAMS, LOOKUP_TYPE *, char *,
177 size_t, int * H_ERRNO_PARM
178 EXTRA_PARAMS);
179
180/* The lookup function for the first entry of this service. */
181extern int DB_LOOKUP_FCT (nss_action_list *nip, const char *name,
182 const char *name2, void **fctp);
183libc_hidden_proto (DB_LOOKUP_FCT)
184
185
186int
187INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
188 size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM
189 EXTRA_PARAMS)
190{
191 nss_action_list nip;
192 int do_merge = 0;
193 LOOKUP_TYPE mergegrp;
194 char *mergebuf = NULL;
195 char *endptr = NULL;
196 union
197 {
198 lookup_function l;
199 void *ptr;
200 } fct;
201 int no_more, err;
202 enum nss_status status = NSS_STATUS_UNAVAIL;
203#ifdef USE_NSCD
204 int nscd_status;
205#endif
206#ifdef NEED_H_ERRNO
207 bool any_service = false;
208#endif
209
210#ifdef NEED__RES
211 /* The HANDLE_DIGITS_DOTS case below already needs the resolver
212 configuration, so this has to happen early. */
213 struct resolv_context *res_ctx = __resolv_context_get ();
214 if (res_ctx == NULL)
215 {
216 *h_errnop = NETDB_INTERNAL;
217 *result = NULL;
218 return errno;
219 }
220#endif /* NEED__RES */
221
222#ifdef PREPROCESS
223 PREPROCESS;
224#endif
225
226
227#ifdef HANDLE_DIGITS_DOTS
228 switch (__nss_hostname_digits_dots (name, resbuf, &buffer, NULL,
229 buflen, result, &status, AF_VAL,
230 H_ERRNO_VAR_P))
231 {
232 case -1:
233# ifdef NEED__RES
234 __resolv_context_put (res_ctx);
235# endif
236 return errno;
237 case 1:
238#ifdef NEED_H_ERRNO
239 any_service = true;
240#endif
241 goto done;
242 }
243#endif
244
245#ifdef USE_NSCD
246 if (NOT_USENSCD_NAME > 0 && ++NOT_USENSCD_NAME > NSS_NSCD_RETRY)
247 NOT_USENSCD_NAME = 0;
248
249 if (!NOT_USENSCD_NAME
250 && !__nss_database_custom[CONCAT2 (NSS_DBSIDX_, DATABASE_NAME)])
251 {
252 nscd_status = NSCD_NAME (ADD_VARIABLES, resbuf, buffer, buflen, result
253 H_ERRNO_VAR);
254 if (nscd_status >= 0)
255 {
256# ifdef NEED__RES
257 __resolv_context_put (res_ctx);
258# endif
259 return nscd_status;
260 }
261 }
262#endif
263
264 no_more = DB_LOOKUP_FCT (&nip, REENTRANT_NAME_STRING,
265 REENTRANT2_NAME_STRING, &fct.ptr);
266
267 while (no_more == 0)
268 {
269#ifdef NEED_H_ERRNO
270 any_service = true;
271#endif
272
273 status = DL_CALL_FCT (fct.l, (ADD_VARIABLES, resbuf, buffer, buflen,
274 &errno H_ERRNO_VAR EXTRA_VARIABLES));
275
276 /* The status is NSS_STATUS_TRYAGAIN and errno is ERANGE the
277 provided buffer is too small. In this case we should give
278 the user the possibility to enlarge the buffer and we should
279 not simply go on with the next service (even if the TRYAGAIN
280 action tells us so). */
281 if (status == NSS_STATUS_TRYAGAIN
282#ifdef NEED_H_ERRNO
283 && *h_errnop == NETDB_INTERNAL
284#endif
285 && errno == ERANGE)
286 break;
287
288 if (do_merge)
289 {
290
291 if (status == NSS_STATUS_SUCCESS)
292 {
293 /* The previous loop saved a buffer for merging.
294 Perform the merge now. */
295 err = MERGE_FN (&mergegrp, mergebuf, endptr, buflen, resbuf,
296 buffer);
297 CHECK_MERGE (err,status);
298 do_merge = 0;
299 }
300 else
301 {
302 /* If the result wasn't SUCCESS, copy the saved buffer back
303 into the result buffer and set the status back to
304 NSS_STATUS_SUCCESS to match the previous pass through the
305 loop.
306 * If the next action is CONTINUE, it will overwrite the value
307 currently in the buffer and return the new value.
308 * If the next action is RETURN, we'll return the previously-
309 acquired values.
310 * If the next action is MERGE, then it will be added to the
311 buffer saved from the previous source. */
312 err = DEEPCOPY_FN (mergegrp, buflen, resbuf, buffer, NULL);
313 CHECK_MERGE (err, status);
314 status = NSS_STATUS_SUCCESS;
315 }
316 }
317
318 /* If we were are configured to merge this value with the next one,
319 save the current value of the group struct. */
320 if (nss_next_action (nip, status) == NSS_ACTION_MERGE
321 && status == NSS_STATUS_SUCCESS)
322 {
323 /* Copy the current values into a buffer to be merged with the next
324 set of retrieved values. */
325 if (mergebuf == NULL)
326 {
327 /* Only allocate once and reuse it for as many merges as we need
328 to perform. */
329 mergebuf = malloc (buflen);
330 if (mergebuf == NULL)
331 {
332 __set_errno (ENOMEM);
333 status = NSS_STATUS_UNAVAIL;
334 break;
335 }
336 }
337
338 err = DEEPCOPY_FN (*resbuf, buflen, &mergegrp, mergebuf, &endptr);
339 CHECK_MERGE (err, status);
340 do_merge = 1;
341 }
342
343 no_more = __nss_next2 (&nip, REENTRANT_NAME_STRING,
344 REENTRANT2_NAME_STRING, &fct.ptr, status, 0);
345 }
346 free (mergebuf);
347 mergebuf = NULL;
348
349#ifdef HANDLE_DIGITS_DOTS
350done:
351#endif
352 *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
353#ifdef NEED_H_ERRNO
354 if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)
355 /* This happens when we weren't able to use a service for reasons other
356 than the module not being found. In such a case, we'd want to tell the
357 caller that errno has the real reason for failure. */
358 *h_errnop = NETDB_INTERNAL;
359 else if (status != NSS_STATUS_SUCCESS && !any_service)
360 /* We were not able to use any service. */
361 *h_errnop = NO_RECOVERY;
362#endif
363#ifdef POSTPROCESS
364 POSTPROCESS;
365#endif
366
367#ifdef NEED__RES
368 /* This has to happen late because the POSTPROCESS stage above might
369 need the resolver context. */
370 __resolv_context_put (res_ctx);
371#endif /* NEED__RES */
372
373 int res;
374 if (status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND)
375 res = 0;
376 /* Don't pass back ERANGE if this is not for a too-small buffer. */
377 else if (errno == ERANGE && status != NSS_STATUS_TRYAGAIN)
378 res = EINVAL;
379#ifdef NEED_H_ERRNO
380 /* These functions only set errno if h_errno is NETDB_INTERNAL. */
381 else if (status == NSS_STATUS_TRYAGAIN && *h_errnop != NETDB_INTERNAL)
382 res = EAGAIN;
383#endif
384 else
385 return errno;
386
387 __set_errno (res);
388 return res;
389}
390
391
392#ifdef NO_COMPAT_NEEDED
393strong_alias (INTERNAL (REENTRANT_NAME), REENTRANT_NAME);
394#elif !defined FUNCTION2_NAME
395# include <shlib-compat.h>
396# if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1_2)
397# define OLD(name) OLD1 (name)
398# define OLD1(name) __old_##name
399
400int
401attribute_compat_text_section
402OLD (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
403 size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM)
404{
405 int ret = INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, resbuf, buffer,
406 buflen, result H_ERRNO_VAR);
407
408 if (ret != 0 || result == NULL)
409 ret = -1;
410
411 return ret;
412}
413
414# define do_symbol_version(real, name, version) \
415 compat_symbol (libc, real, name, version)
416do_symbol_version (OLD (REENTRANT_NAME), REENTRANT_NAME, GLIBC_2_0);
417# endif
418
419/* As INTERNAL (REENTRANT_NAME) may be hidden, we need an alias
420 in between so that the REENTRANT_NAME@@GLIBC_2.1.2 is not
421 hidden too. */
422strong_alias (INTERNAL (REENTRANT_NAME), NEW (REENTRANT_NAME));
423
424# define do_default_symbol_version(real, name, version) \
425 versioned_symbol (libc, real, name, version)
426do_default_symbol_version (NEW (REENTRANT_NAME),
427 REENTRANT_NAME, GLIBC_2_1_2);
428#endif
429
430nss_interface_function (REENTRANT_NAME)
431