nss/getXXbyYY.c

   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 <errno.h>
  20 #include <libc-lock.h>
  21 #include <stdlib.h>
  22 #include <resolv.h>
  23 #include <set-freeres.h>
  24
  25 #include "nsswitch.h"
  26
  27 /*******************************************************************\
  28 |* Here we assume several symbols to be defined:                   *|
  29 |*                                                                 *|
  30 |* LOOKUP_TYPE   - the return type of the function                 *|
  31 |*                                                                 *|
  32 |* FUNCTION_NAME - name of the non-reentrant function              *|
  33 |*                                                                 *|
  34 |* DATABASE_NAME - name of the database the function accesses      *|
  35 |*                 (e.g., host, services, ...)                     *|
  36 |*                                                                 *|
  37 |* ADD_PARAMS    - additional parameter, can vary in number        *|
  38 |*                                                                 *|
  39 |* ADD_VARIABLES - names of additional parameter                   *|
  40 |*                                                                 *|
  41 |* BUFLEN        - length of buffer allocated for the non          *|
  42 |*                 reentrant version                               *|
  43 |*                                                                 *|
  44 |* Optionally the following vars can be defined:                   *|
  45 |*                                                                 *|
  46 |* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|
  47 |*                 the global `h_errno' variable.                  *|
  48 |*                                                                 *|
  49 \*******************************************************************/
  50
  51
  52 #ifdef HANDLE_DIGITS_DOTS
  53 # include <resolv/resolv_context.h>
  54 #endif
  55
  56 /* To make the real sources a bit prettier.  */
  57 #define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
  58 #define APPEND_R(name) APPEND_R1 (name)
  59 #define APPEND_R1(name) name##_r
  60 #define INTERNAL(name) INTERNAL1 (name)
  61 #define INTERNAL1(name) __##name
  62 #define APPEND_FREEMEM_NAME1(name) __libc_##name##_freemem_ptr
  63 #define APPEND_FREEMEM_NAME(name) APPEND_FREEMEM_NAME1(name)
  64 #define FREEMEM_NAME APPEND_FREEMEM_NAME (FUNCTION_NAME)
  65
  66 /* Sometimes we need to store error codes in the `h_errno' variable.  */
  67 #ifdef NEED_H_ERRNO
  68 # define H_ERRNO_PARM , int *h_errnop
  69 # define H_ERRNO_VAR , &h_errno_tmp
  70 # define H_ERRNO_VAR_P &h_errno_tmp
  71 #else
  72 # define H_ERRNO_PARM
  73 # define H_ERRNO_VAR
  74 # define H_ERRNO_VAR_P NULL
  75 #endif
  76
  77 #ifdef HAVE_AF
  78 # define AF_VAL af
  79 #else
  80 # define AF_VAL AF_INET
  81 #endif
  82
  83 /* Prototype for reentrant version we use here.  */
  84 extern int INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf,
  85                                       char *buffer, size_t buflen,
  86                                       LOOKUP_TYPE **result H_ERRNO_PARM)
  87      attribute_hidden;
  88
  89 /* We need to protect the dynamic buffer handling.  */
  90 __libc_lock_define_initialized (static, lock);
  91
  92 /* This points to the static buffer used.  */
  93 static char *buffer;
  94
  95 weak_alias (buffer, FREEMEM_NAME)
  96
  97 LOOKUP_TYPE *
  98 FUNCTION_NAME (ADD_PARAMS)
  99 {
 100   static size_t buffer_size;
 101   static LOOKUP_TYPE resbuf;
 102   LOOKUP_TYPE *result;
 103 #ifdef NEED_H_ERRNO
 104   int h_errno_tmp = 0;
 105 #endif
 106
 107 #ifdef HANDLE_DIGITS_DOTS
 108   /* Wrap both __nss_hostname_digits_dots and the actual lookup
 109      function call in the same context.  */
 110   struct resolv_context *res_ctx = __resolv_context_get ();
 111   if (res_ctx == NULL)
 112     {
 113 # if NEED_H_ERRNO
 114       __set_h_errno (NETDB_INTERNAL);
 115 # endif
 116       return NULL;
 117     }
 118 #endif
 119
 120   /* Get lock.  */
 121   __libc_lock_lock (lock);
 122
 123   if (buffer == NULL)
 124     {
 125       buffer_size = BUFLEN;
 126       buffer = (char *) malloc (buffer_size);
 127     }
 128
 129 #ifdef HANDLE_DIGITS_DOTS
 130   if (buffer != NULL)
 131     {
 132       if (__nss_hostname_digits_dots_context
 133           (res_ctx, name, &resbuf, &buffer, &buffer_size, 0, &result, NULL,
 134            AF_VAL, H_ERRNO_VAR_P))
 135         goto done;
 136     }
 137 #endif
 138
 139   while (buffer != NULL
 140          && (INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, &resbuf, buffer,
 141                                         buffer_size, &result H_ERRNO_VAR)
 142              == ERANGE)
 143 #ifdef NEED_H_ERRNO
 144          && h_errno_tmp == NETDB_INTERNAL
 145 #endif
 146          )
 147     {
 148       char *new_buf;
 149       buffer_size *= 2;
 150       new_buf = (char *) realloc (buffer, buffer_size);
 151       if (new_buf == NULL)
 152         {
 153           /* We are out of memory.  Free the current buffer so that the
 154              process gets a chance for a normal termination.  */
 155           free (buffer);
 156           __set_errno (ENOMEM);
 157         }
 158       buffer = new_buf;
 159     }
 160
 161   if (buffer == NULL)
 162     result = NULL;
 163
 164 #ifdef HANDLE_DIGITS_DOTS
 165 done:
 166 #endif
 167   /* Release lock.  */
 168   __libc_lock_unlock (lock);
 169
 170 #ifdef HANDLE_DIGITS_DOTS
 171   __resolv_context_put (res_ctx);
 172 #endif
 173
 174 #ifdef NEED_H_ERRNO
 175   if (h_errno_tmp != 0)
 176     __set_h_errno (h_errno_tmp);
 177 #endif
 178
 179   return result;
 180 }
 181
 182 nss_interface_function (FUNCTION_NAME)