nss/getXXbyYY_r.c

   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
 133 static 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
 146 static 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.  */
 177 typedef 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.  */
 182 extern int DB_LOOKUP_FCT (nss_action_list *nip, const char *name,
 183                           const char *name2, void **fctp);
 184 libc_hidden_proto (DB_LOOKUP_FCT)
 185
 186
 187 int
 188 INTERNAL (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
 351 done:
 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
 394 strong_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
 401 int
 402 attribute_compat_text_section
 403 OLD (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)
 417 do_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.  */
 423 strong_alias (INTERNAL (REENTRANT_NAME), NEW (REENTRANT_NAME));
 424
 425 # define do_default_symbol_version(real, name, version) \
 426   versioned_symbol (libc, real, name, version)
 427 do_default_symbol_version (NEW (REENTRANT_NAME),
 428                            REENTRANT_NAME, GLIBC_2_1_2);
 429 #endif
 430
 431 nss_interface_function (REENTRANT_NAME)