nss/getXXbyYY_r.c

   1 /* Copyright (C) 1996-2019 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
 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 (service_user **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   static bool startp_initialized;
 193   static service_user *startp;
 194   static lookup_function start_fct;
 195   service_user *nip;
 196   int do_merge = 0;
 197   LOOKUP_TYPE mergegrp;
 198   char *mergebuf = NULL;
 199   char *endptr = NULL;
 200   union
 201   {
 202     lookup_function l;
 203     void *ptr;
 204   } fct;
 205   int no_more, err;
 206   enum nss_status status = NSS_STATUS_UNAVAIL;
 207 #ifdef USE_NSCD
 208   int nscd_status;
 209 #endif
 210 #ifdef NEED_H_ERRNO
 211   bool any_service = false;
 212 #endif
 213
 214 #ifdef NEED__RES
 215   /* The HANDLE_DIGITS_DOTS case below already needs the resolver
 216      configuration, so this has to happen early.  */
 217   struct resolv_context *res_ctx = __resolv_context_get ();
 218   if (res_ctx == NULL)
 219     {
 220       *h_errnop = NETDB_INTERNAL;
 221       *result = NULL;
 222       return errno;
 223     }
 224 #endif /* NEED__RES */
 225
 226 #ifdef PREPROCESS
 227   PREPROCESS;
 228 #endif
 229
 230 #ifdef HANDLE_DIGITS_DOTS
 231   switch (__nss_hostname_digits_dots (name, resbuf, &buffer, NULL,
 232                                       buflen, result, &status, AF_VAL,
 233                                       H_ERRNO_VAR_P))
 234     {
 235     case -1:
 236 # ifdef NEED__RES
 237       __resolv_context_put (res_ctx);
 238 # endif
 239       return errno;
 240     case 1:
 241 #ifdef NEED_H_ERRNO
 242       any_service = true;
 243 #endif
 244       goto done;
 245     }
 246 #endif
 247
 248 #ifdef USE_NSCD
 249   if (NOT_USENSCD_NAME > 0 && ++NOT_USENSCD_NAME > NSS_NSCD_RETRY)
 250     NOT_USENSCD_NAME = 0;
 251
 252   if (!NOT_USENSCD_NAME
 253       && !__nss_database_custom[CONCAT2 (NSS_DBSIDX_, DATABASE_NAME)])
 254     {
 255       nscd_status = NSCD_NAME (ADD_VARIABLES, resbuf, buffer, buflen, result
 256                                H_ERRNO_VAR);
 257       if (nscd_status >= 0)
 258         {
 259 # ifdef NEED__RES
 260           __resolv_context_put (res_ctx);
 261 # endif
 262           return nscd_status;
 263         }
 264     }
 265 #endif
 266
 267   if (! startp_initialized)
 268     {
 269       no_more = DB_LOOKUP_FCT (&nip, REENTRANT_NAME_STRING,
 270                                REENTRANT2_NAME_STRING, &fct.ptr);
 271       if (no_more)
 272         {
 273           void *tmp_ptr = (service_user *) -1l;
 274 #ifdef PTR_MANGLE
 275           PTR_MANGLE (tmp_ptr);
 276 #endif
 277           startp = tmp_ptr;
 278         }
 279       else
 280         {
 281           void *tmp_ptr = fct.l;
 282 #ifdef PTR_MANGLE
 283           PTR_MANGLE (tmp_ptr);
 284 #endif
 285           start_fct = tmp_ptr;
 286           tmp_ptr = nip;
 287 #ifdef PTR_MANGLE
 288           PTR_MANGLE (tmp_ptr);
 289 #endif
 290           startp = tmp_ptr;
 291         }
 292
 293       /* Make sure start_fct and startp are written before
 294          startp_initialized.  */
 295       atomic_write_barrier ();
 296       startp_initialized = true;
 297     }
 298   else
 299     {
 300       fct.l = start_fct;
 301       nip = startp;
 302 #ifdef PTR_DEMANGLE
 303       PTR_DEMANGLE (fct.l);
 304       PTR_DEMANGLE (nip);
 305 #endif
 306       no_more = nip == (service_user *) -1l;
 307     }
 308
 309   while (no_more == 0)
 310     {
 311 #ifdef NEED_H_ERRNO
 312       any_service = true;
 313 #endif
 314
 315       status = DL_CALL_FCT (fct.l, (ADD_VARIABLES, resbuf, buffer, buflen,
 316                                     &errno H_ERRNO_VAR EXTRA_VARIABLES));
 317
 318       /* The status is NSS_STATUS_TRYAGAIN and errno is ERANGE the
 319          provided buffer is too small.  In this case we should give
 320          the user the possibility to enlarge the buffer and we should
 321          not simply go on with the next service (even if the TRYAGAIN
 322          action tells us so).  */
 323       if (status == NSS_STATUS_TRYAGAIN
 324 #ifdef NEED_H_ERRNO
 325           && *h_errnop == NETDB_INTERNAL
 326 #endif
 327           && errno == ERANGE)
 328         break;
 329
 330       if (do_merge)
 331         {
 332
 333           if (status == NSS_STATUS_SUCCESS)
 334             {
 335               /* The previous loop saved a buffer for merging.
 336                  Perform the merge now.  */
 337               err = MERGE_FN (&mergegrp, mergebuf, endptr, buflen, resbuf,
 338                               buffer);
 339               CHECK_MERGE (err,status);
 340               do_merge = 0;
 341             }
 342           else
 343             {
 344               /* If the result wasn't SUCCESS, copy the saved buffer back
 345                  into the result buffer and set the status back to
 346                  NSS_STATUS_SUCCESS to match the previous pass through the
 347                  loop.
 348                   * If the next action is CONTINUE, it will overwrite the value
 349                     currently in the buffer and return the new value.
 350                   * If the next action is RETURN, we'll return the previously-
 351                     acquired values.
 352                   * If the next action is MERGE, then it will be added to the
 353                     buffer saved from the previous source.  */
 354               err = DEEPCOPY_FN (mergegrp, buflen, resbuf, buffer, NULL);
 355               CHECK_MERGE (err, status);
 356               status = NSS_STATUS_SUCCESS;
 357             }
 358         }
 359
 360       /* If we were are configured to merge this value with the next one,
 361          save the current value of the group struct.  */
 362       if (nss_next_action (nip, status) == NSS_ACTION_MERGE
 363           && status == NSS_STATUS_SUCCESS)
 364         {
 365           /* Copy the current values into a buffer to be merged with the next
 366              set of retrieved values.  */
 367           if (mergebuf == NULL)
 368             {
 369               /* Only allocate once and reuse it for as many merges as we need
 370                  to perform.  */
 371               mergebuf = malloc (buflen);
 372               if (mergebuf == NULL)
 373                 {
 374                   __set_errno (ENOMEM);
 375                   status = NSS_STATUS_UNAVAIL;
 376                   break;
 377                 }
 378             }
 379
 380           err = DEEPCOPY_FN (*resbuf, buflen, &mergegrp, mergebuf, &endptr);
 381           CHECK_MERGE (err, status);
 382           do_merge = 1;
 383         }
 384
 385       no_more = __nss_next2 (&nip, REENTRANT_NAME_STRING,
 386                              REENTRANT2_NAME_STRING, &fct.ptr, status, 0);
 387     }
 388   free (mergebuf);
 389   mergebuf = NULL;
 390
 391 #ifdef HANDLE_DIGITS_DOTS
 392 done:
 393 #endif
 394   *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
 395 #ifdef NEED_H_ERRNO
 396   if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)
 397     /* This happens when we weren't able to use a service for reasons other
 398        than the module not being found.  In such a case, we'd want to tell the
 399        caller that errno has the real reason for failure.  */
 400     *h_errnop = NETDB_INTERNAL;
 401   else if (status != NSS_STATUS_SUCCESS && !any_service)
 402     /* We were not able to use any service.  */
 403     *h_errnop = NO_RECOVERY;
 404 #endif
 405 #ifdef POSTPROCESS
 406   POSTPROCESS;
 407 #endif
 408
 409 #ifdef NEED__RES
 410   /* This has to happen late because the POSTPROCESS stage above might
 411      need the resolver context.  */
 412   __resolv_context_put (res_ctx);
 413 #endif /* NEED__RES */
 414
 415   int res;
 416   if (status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND)
 417     res = 0;
 418   /* Don't pass back ERANGE if this is not for a too-small buffer.  */
 419   else if (errno == ERANGE && status != NSS_STATUS_TRYAGAIN)
 420     res = EINVAL;
 421 #ifdef NEED_H_ERRNO
 422   /* These functions only set errno if h_errno is NETDB_INTERNAL.  */
 423   else if (status == NSS_STATUS_TRYAGAIN && *h_errnop != NETDB_INTERNAL)
 424     res = EAGAIN;
 425 #endif
 426   else
 427     return errno;
 428
 429   __set_errno (res);
 430   return res;
 431 }
 432
 433
 434 #ifdef NO_COMPAT_NEEDED
 435 strong_alias (INTERNAL (REENTRANT_NAME), REENTRANT_NAME);
 436 #elif !defined FUNCTION2_NAME
 437 # include <shlib-compat.h>
 438 # if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1_2)
 439 #  define OLD(name) OLD1 (name)
 440 #  define OLD1(name) __old_##name
 441
 442 int
 443 attribute_compat_text_section
 444 OLD (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
 445                       size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM)
 446 {
 447   int ret = INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, resbuf, buffer,
 448                                        buflen, result H_ERRNO_VAR);
 449
 450   if (ret != 0 || result == NULL)
 451     ret = -1;
 452
 453   return ret;
 454 }
 455
 456 #  define do_symbol_version(real, name, version) \
 457   compat_symbol (libc, real, name, version)
 458 do_symbol_version (OLD (REENTRANT_NAME), REENTRANT_NAME, GLIBC_2_0);
 459 # endif
 460
 461 /* As INTERNAL (REENTRANT_NAME) may be hidden, we need an alias
 462    in between so that the REENTRANT_NAME@@GLIBC_2.1.2 is not
 463    hidden too.  */
 464 strong_alias (INTERNAL (REENTRANT_NAME), NEW (REENTRANT_NAME));
 465
 466 # define do_default_symbol_version(real, name, version) \
 467   versioned_symbol (libc, real, name, version)
 468 do_default_symbol_version (NEW (REENTRANT_NAME),
 469                            REENTRANT_NAME, GLIBC_2_1_2);
 470 #endif
 471
 472 nss_interface_function (REENTRANT_NAME)