nss/getXXbyYY_r.c

   1 /* Copyright (C) 1996-2016 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_HCONF
  29 # include <resolv/res_hconf.h>
  30 #endif
  31 #ifdef NEED__RES
  32 # include <resolv.h>
  33 #endif
  34 /*******************************************************************\
  35 |* Here we assume several symbols to be defined:                   *|
  36 |*                                                                 *|
  37 |* LOOKUP_TYPE   - the return type of the function                 *|
  38 |*                                                                 *|
  39 |* FUNCTION_NAME - name of the non-reentrant function              *|
  40 |*                                                                 *|
  41 |* DATABASE_NAME - name of the database the function accesses      *|
  42 |*                 (e.g., host, services, ...)                     *|
  43 |*                                                                 *|
  44 |* ADD_PARAMS    - additional parameters, can vary in number       *|
  45 |*                                                                 *|
  46 |* ADD_VARIABLES - names of additional parameters                  *|
  47 |*                                                                 *|
  48 |* Optionally the following vars can be defined:                   *|
  49 |*                                                                 *|
  50 |* EXTRA_PARAMS  - optional parameters, can vary in number         *|
  51 |*                                                                 *|
  52 |* EXTRA_VARIABLES - names of optional parameter                   *|
  53 |*                                                                 *|
  54 |* FUNCTION2_NAME - alternative name of the non-reentrant function *|
  55 |*                                                                 *|
  56 |* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|
  57 |*                 the global `h_errno' variable.                  *|
  58 |*                                                                 *|
  59 |* NEED__RES     - the global _res variable might be used so we    *|
  60 |*                 will have to initialize it if necessary         *|
  61 |*                                                                 *|
  62 |* PREPROCESS    - code run before anything else                   *|
  63 |*                                                                 *|
  64 |* POSTPROCESS   - code run after the lookup                       *|
  65 |*                                                                 *|
  66 \*******************************************************************/
  67
  68 /* To make the real sources a bit prettier.  */
  69 #define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
  70 #ifdef FUNCTION2_NAME
  71 # define REENTRANT2_NAME APPEND_R (FUNCTION2_NAME)
  72 #else
  73 # define REENTRANT2_NAME NULL
  74 #endif
  75 #define APPEND_R(name) APPEND_R1 (name)
  76 #define APPEND_R1(name) name##_r
  77 #define INTERNAL(name) INTERNAL1 (name)
  78 #define INTERNAL1(name) __##name
  79 #define NEW(name) NEW1 (name)
  80 #define NEW1(name) __new_##name
  81
  82 #ifdef USE_NSCD
  83 # define NSCD_NAME ADD_NSCD (REENTRANT_NAME)
  84 # define ADD_NSCD(name) ADD_NSCD1 (name)
  85 # define ADD_NSCD1(name) __nscd_##name
  86 # define NOT_USENSCD_NAME ADD_NOT_NSCDUSE (DATABASE_NAME)
  87 # define ADD_NOT_NSCDUSE(name) ADD_NOT_NSCDUSE1 (name)
  88 # define ADD_NOT_NSCDUSE1(name) __nss_not_use_nscd_##name
  89 # define CONCAT2(arg1, arg2) CONCAT2_2 (arg1, arg2)
  90 # define CONCAT2_2(arg1, arg2) arg1##arg2
  91 #endif
  92
  93 #define FUNCTION_NAME_STRING STRINGIZE (FUNCTION_NAME)
  94 #define REENTRANT_NAME_STRING STRINGIZE (REENTRANT_NAME)
  95 #ifdef FUNCTION2_NAME
  96 # define REENTRANT2_NAME_STRING STRINGIZE (REENTRANT2_NAME)
  97 #else
  98 # define REENTRANT2_NAME_STRING NULL
  99 #endif
 100 #define DATABASE_NAME_STRING STRINGIZE (DATABASE_NAME)
 101 #define STRINGIZE(name) STRINGIZE1 (name)
 102 #define STRINGIZE1(name) #name
 103
 104 #ifndef DB_LOOKUP_FCT
 105 # define DB_LOOKUP_FCT CONCAT3_1 (__nss_, DATABASE_NAME, _lookup2)
 106 # define CONCAT3_1(Pre, Name, Post) CONCAT3_2 (Pre, Name, Post)
 107 # define CONCAT3_2(Pre, Name, Post) Pre##Name##Post
 108 #endif
 109
 110 /* Sometimes we need to store error codes in the `h_errno' variable.  */
 111 #ifdef NEED_H_ERRNO
 112 # define H_ERRNO_PARM , int *h_errnop
 113 # define H_ERRNO_VAR , h_errnop
 114 # define H_ERRNO_VAR_P h_errnop
 115 #else
 116 # define H_ERRNO_PARM
 117 # define H_ERRNO_VAR
 118 # define H_ERRNO_VAR_P NULL
 119 #endif
 120
 121 #ifndef EXTRA_PARAMS
 122 # define EXTRA_PARAMS
 123 #endif
 124 #ifndef EXTRA_VARIABLES
 125 # define EXTRA_VARIABLES
 126 #endif
 127
 128 #ifdef HAVE_AF
 129 # define AF_VAL af
 130 #else
 131 # define AF_VAL AF_INET
 132 #endif
 133
 134 /* Type of the lookup function we need here.  */
 135 typedef enum nss_status (*lookup_function) (ADD_PARAMS, LOOKUP_TYPE *, char *,
 136                                             size_t, int * H_ERRNO_PARM
 137                                             EXTRA_PARAMS);
 138
 139 /* The lookup function for the first entry of this service.  */
 140 extern int DB_LOOKUP_FCT (service_user **nip, const char *name,
 141                           const char *name2, void **fctp)
 142      internal_function;
 143 libc_hidden_proto (DB_LOOKUP_FCT)
 144
 145
 146 int
 147 INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
 148                            size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM
 149                            EXTRA_PARAMS)
 150 {
 151   static bool startp_initialized;
 152   static service_user *startp;
 153   static lookup_function start_fct;
 154   service_user *nip;
 155   union
 156   {
 157     lookup_function l;
 158     void *ptr;
 159   } fct;
 160
 161   int no_more;
 162   enum nss_status status = NSS_STATUS_UNAVAIL;
 163 #ifdef USE_NSCD
 164   int nscd_status;
 165 #endif
 166 #ifdef NEED_H_ERRNO
 167   bool any_service = false;
 168 #endif
 169
 170 #ifdef PREPROCESS
 171   PREPROCESS;
 172 #endif
 173
 174 #ifdef HANDLE_DIGITS_DOTS
 175   switch (__nss_hostname_digits_dots (name, resbuf, &buffer, NULL,
 176                                       buflen, result, &status, AF_VAL,
 177                                       H_ERRNO_VAR_P))
 178     {
 179     case -1:
 180       return errno;
 181     case 1:
 182 #ifdef NEED_H_ERRNO
 183       any_service = true;
 184 #endif
 185       goto done;
 186     }
 187 #endif
 188
 189 #ifdef USE_NSCD
 190   if (NOT_USENSCD_NAME > 0 && ++NOT_USENSCD_NAME > NSS_NSCD_RETRY)
 191     NOT_USENSCD_NAME = 0;
 192
 193   if (!NOT_USENSCD_NAME
 194       && !__nss_database_custom[CONCAT2 (NSS_DBSIDX_, DATABASE_NAME)])
 195     {
 196       nscd_status = NSCD_NAME (ADD_VARIABLES, resbuf, buffer, buflen, result
 197                                H_ERRNO_VAR);
 198       if (nscd_status >= 0)
 199         return nscd_status;
 200     }
 201 #endif
 202
 203   if (! startp_initialized)
 204     {
 205       no_more = DB_LOOKUP_FCT (&nip, REENTRANT_NAME_STRING,
 206                                REENTRANT2_NAME_STRING, &fct.ptr);
 207       if (no_more)
 208         {
 209           void *tmp_ptr = (service_user *) -1l;
 210 #ifdef PTR_MANGLE
 211           PTR_MANGLE (tmp_ptr);
 212 #endif
 213           startp = tmp_ptr;
 214         }
 215       else
 216         {
 217 #ifdef NEED__RES
 218           /* The resolver code will really be used so we have to
 219              initialize it.  */
 220           if (__res_maybe_init (&_res, 0) == -1)
 221             {
 222               *h_errnop = NETDB_INTERNAL;
 223               *result = NULL;
 224               return errno;
 225             }
 226 #endif /* need _res */
 227 #ifdef NEED__RES_HCONF
 228           if (!_res_hconf.initialized)
 229             _res_hconf_init ();
 230 #endif /* need _res_hconf */
 231
 232           void *tmp_ptr = fct.l;
 233 #ifdef PTR_MANGLE
 234           PTR_MANGLE (tmp_ptr);
 235 #endif
 236           start_fct = tmp_ptr;
 237           tmp_ptr = nip;
 238 #ifdef PTR_MANGLE
 239           PTR_MANGLE (tmp_ptr);
 240 #endif
 241           startp = tmp_ptr;
 242         }
 243
 244       /* Make sure start_fct and startp are written before
 245          startp_initialized.  */
 246       atomic_write_barrier ();
 247       startp_initialized = true;
 248     }
 249   else
 250     {
 251       fct.l = start_fct;
 252       nip = startp;
 253 #ifdef PTR_DEMANGLE
 254       PTR_DEMANGLE (fct.l);
 255       PTR_DEMANGLE (nip);
 256 #endif
 257       no_more = nip == (service_user *) -1l;
 258     }
 259
 260   while (no_more == 0)
 261     {
 262 #ifdef NEED_H_ERRNO
 263       any_service = true;
 264 #endif
 265
 266       status = DL_CALL_FCT (fct.l, (ADD_VARIABLES, resbuf, buffer, buflen,
 267                                     &errno H_ERRNO_VAR EXTRA_VARIABLES));
 268
 269       /* The status is NSS_STATUS_TRYAGAIN and errno is ERANGE the
 270          provided buffer is too small.  In this case we should give
 271          the user the possibility to enlarge the buffer and we should
 272          not simply go on with the next service (even if the TRYAGAIN
 273          action tells us so).  */
 274       if (status == NSS_STATUS_TRYAGAIN
 275 #ifdef NEED_H_ERRNO
 276           && *h_errnop == NETDB_INTERNAL
 277 #endif
 278           && errno == ERANGE)
 279         break;
 280
 281       no_more = __nss_next2 (&nip, REENTRANT_NAME_STRING,
 282                              REENTRANT2_NAME_STRING, &fct.ptr, status, 0);
 283     }
 284
 285 #ifdef HANDLE_DIGITS_DOTS
 286 done:
 287 #endif
 288   *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
 289 #ifdef NEED_H_ERRNO
 290   if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)
 291     /* This happens when we weren't able to use a service for reasons other
 292        than the module not being found.  In such a case, we'd want to tell the
 293        caller that errno has the real reason for failure.  */
 294     *h_errnop = NETDB_INTERNAL;
 295   else if (status != NSS_STATUS_SUCCESS && !any_service)
 296     /* We were not able to use any service.  */
 297     *h_errnop = NO_RECOVERY;
 298 #endif
 299 #ifdef POSTPROCESS
 300   POSTPROCESS;
 301 #endif
 302
 303   int res;
 304   if (status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND)
 305     res = 0;
 306   /* Don't pass back ERANGE if this is not for a too-small buffer.  */
 307   else if (errno == ERANGE && status != NSS_STATUS_TRYAGAIN)
 308     res = EINVAL;
 309 #ifdef NEED_H_ERRNO
 310   /* These functions only set errno if h_errno is NETDB_INTERNAL.  */
 311   else if (status == NSS_STATUS_TRYAGAIN && *h_errnop != NETDB_INTERNAL)
 312     res = EAGAIN;
 313 #endif
 314   else
 315     return errno;
 316
 317   __set_errno (res);
 318   return res;
 319 }
 320
 321
 322 #ifdef NO_COMPAT_NEEDED
 323 strong_alias (INTERNAL (REENTRANT_NAME), REENTRANT_NAME);
 324 #elif !defined FUNCTION2_NAME
 325 # include <shlib-compat.h>
 326 # if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1_2)
 327 #  define OLD(name) OLD1 (name)
 328 #  define OLD1(name) __old_##name
 329
 330 int
 331 attribute_compat_text_section
 332 OLD (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
 333                       size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM)
 334 {
 335   int ret = INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, resbuf, buffer,
 336                                        buflen, result H_ERRNO_VAR);
 337
 338   if (ret != 0 || result == NULL)
 339     ret = -1;
 340
 341   return ret;
 342 }
 343
 344 #  define do_symbol_version(real, name, version) \
 345   compat_symbol (libc, real, name, version)
 346 do_symbol_version (OLD (REENTRANT_NAME), REENTRANT_NAME, GLIBC_2_0);
 347 # endif
 348
 349 /* As INTERNAL (REENTRANT_NAME) may be hidden, we need an alias
 350    in between so that the REENTRANT_NAME@@GLIBC_2.1.2 is not
 351    hidden too.  */
 352 strong_alias (INTERNAL (REENTRANT_NAME), NEW (REENTRANT_NAME));
 353
 354 # define do_default_symbol_version(real, name, version) \
 355   versioned_symbol (libc, real, name, version)
 356 do_default_symbol_version (NEW (REENTRANT_NAME),
 357                            REENTRANT_NAME, GLIBC_2_1_2);
 358 #endif
 359
 360 nss_interface_function (REENTRANT_NAME)