nscd/nscd_getai.c

   1 /* Copyright (C) 2004 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
   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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <netdb.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <not-cancel.h>
  27
  28 #include "nscd-client.h"
  29 #include "nscd_proto.h"
  30
  31
  32 /* Define in nscd_gethst_r.c.  */
  33 extern int __nss_not_use_nscd_hosts;
  34
  35
  36 libc_locked_map_ptr (map_handle);
  37 /* Note that we only free the structure if necessary.  The memory
  38    mapping is not removed since it is not visible to the malloc
  39    handling.  */
  40 libc_freeres_fn (ai_map_free)
  41 {
  42   if (map_handle.mapped != NO_MAPPING)
  43     free (map_handle.mapped);
  44 }
  45
  46
  47 int
  48 __nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
  49 {
  50   size_t keylen = strlen (key) + 1;
  51   int gc_cycle;
  52
  53   /* If the mapping is available, try to search there instead of
  54      communicating with the nscd.  */
  55   struct mapped_database *mapped;
  56   mapped = __nscd_get_map_ref (GETFDHST, "hosts", &map_handle, &gc_cycle);
  57
  58  retry:;
  59   const ai_response_header *ai_resp = NULL;
  60   struct nscd_ai_result *resultbuf = NULL;
  61   const char *recend = (const char *) ~UINTMAX_C (0);
  62   char *respdata = NULL;
  63   int retval = -1;
  64   int sock = -1;
  65
  66   if (mapped != NO_MAPPING)
  67     {
  68       const struct datahead *found = __nscd_cache_search (GETAI, key, keylen,
  69                                                           mapped);
  70       if (found != NULL)
  71         {
  72           ai_resp = &found->data[0].aidata;
  73           respdata = (char *) (ai_resp + 1);
  74           recend = (const char *) found->data + found->recsize;
  75         }
  76     }
  77
  78   /* If we do not have the cache mapped, try to get the data over the
  79      socket.  */
  80   ai_response_header ai_resp_mem;
  81   if (ai_resp == NULL)
  82     {
  83       sock = __nscd_open_socket (key, keylen, GETAI, &ai_resp_mem,
  84                                  sizeof (ai_resp_mem));
  85       if (sock == -1)
  86         {
  87           /* nscd not running or wrong version or hosts caching disabled.  */
  88           __nss_not_use_nscd_hosts = 1;
  89           goto out;
  90         }
  91
  92       ai_resp = &ai_resp_mem;
  93     }
  94
  95   if (ai_resp->found == 1)
  96     {
  97       size_t datalen = ai_resp->naddrs + ai_resp->addrslen + ai_resp->canonlen;
  98
  99       /* This check is really only affects the case where the data
 100          comes from the mapped cache.  */
 101       if ((char *) (ai_resp + 1) + datalen > recend)
 102         {
 103           assert (sock == -1);
 104           goto out;
 105         }
 106
 107       /* Create result.  */
 108       resultbuf = (struct nscd_ai_result *) malloc (sizeof (*resultbuf)
 109                                                     + datalen);
 110       if (resultbuf == NULL)
 111         {
 112           *h_errnop = NETDB_INTERNAL;
 113           return -1;
 114         }
 115
 116       /* Set up the data structure, including pointers.  */
 117       resultbuf->naddrs = ai_resp->naddrs;
 118       resultbuf->addrs = (char *) (resultbuf + 1);
 119       resultbuf->family = (uint8_t *) (resultbuf->addrs + ai_resp->addrslen);
 120       if (ai_resp->canonlen != 0)
 121         resultbuf->canon = (char *) (resultbuf->family + resultbuf->naddrs);
 122       else
 123         resultbuf->canon = NULL;
 124
 125       if (respdata == NULL)
 126         {
 127           /* Read the data from the socket.  */
 128           if ((size_t) TEMP_FAILURE_RETRY (__read (sock, resultbuf + 1,
 129                                                    datalen)) == datalen)
 130             {
 131               retval = 0;
 132               *result = resultbuf;
 133             }
 134           else
 135             {
 136               free (resultbuf);
 137               *h_errnop = NETDB_INTERNAL;
 138             }
 139         }
 140       else
 141         {
 142           /* Copy the data in the block.  */
 143           memcpy (resultbuf + 1, respdata, datalen);
 144
 145           retval = 0;
 146           *result = resultbuf;
 147         }
 148     }
 149   else
 150     {
 151       /* Store the error number.  */
 152       *h_errnop = ai_resp->error;
 153
 154       /* The `errno' to some value != ERANGE.  */
 155       __set_errno (ENOENT);
 156       /* Even though we have not found anything, the result is zero.  */
 157       retval = 0;
 158     }
 159
 160   if (sock != -1)
 161     close_not_cancel_no_status (sock);
 162  out:
 163   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
 164     {
 165       /* When we come here this means there has been a GC cycle while we
 166          were looking for the data.  This means the data might have been
 167          inconsistent.  Retry if possible.  */
 168       if ((gc_cycle & 1) != 0)
 169         {
 170           /* nscd is just running gc now.  Disable using the mapping.  */
 171           __nscd_unmap (mapped);
 172           mapped = NO_MAPPING;
 173         }
 174
 175       free (resultbuf);
 176
 177       goto retry;
 178     }
 179
 180   return retval;
 181 }