nscd/nscd_gethst_r.c

   1 /* Copyright (C) 1998-2002, 2003, 2004 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
   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 <resolv.h>
  24 #include <stdint.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <unistd.h>
  29 #include <arpa/nameser.h>
  30 #include <sys/mman.h>
  31 #include <not-cancel.h>
  32
  33 #include "nscd-client.h"
  34 #include "nscd_proto.h"
  35
  36 int __nss_not_use_nscd_hosts;
  37
  38 static int nscd_gethst_r (const char *key, size_t keylen, request_type type,
  39                           struct hostent *resultbuf, char *buffer,
  40                           size_t buflen, struct hostent **result,
  41                           int *h_errnop) internal_function;
  42
  43
  44 int
  45 __nscd_gethostbyname_r (const char *name, struct hostent *resultbuf,
  46                         char *buffer, size_t buflen, struct hostent **result,
  47                         int *h_errnop)
  48 {
  49   request_type reqtype;
  50
  51   reqtype = (_res.options & RES_USE_INET6) ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
  52
  53   return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
  54                         buffer, buflen, result, h_errnop);
  55 }
  56
  57
  58 int
  59 __nscd_gethostbyname2_r (const char *name, int af, struct hostent *resultbuf,
  60                          char *buffer, size_t buflen, struct hostent **result,
  61                          int *h_errnop)
  62 {
  63   request_type reqtype;
  64
  65   reqtype = af == AF_INET6 ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
  66
  67   return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
  68                         buffer, buflen, result, h_errnop);
  69 }
  70
  71
  72 int
  73 __nscd_gethostbyaddr_r (const void *addr, socklen_t len, int type,
  74                         struct hostent *resultbuf, char *buffer, size_t buflen,
  75                         struct hostent **result, int *h_errnop)
  76 {
  77   request_type reqtype;
  78
  79   if (!((len == INADDRSZ && type == AF_INET)
  80         || (len == IN6ADDRSZ && type == AF_INET6)))
  81     /* LEN and TYPE do not match.  */
  82     return -1;
  83
  84   reqtype = type == AF_INET6 ? GETHOSTBYADDRv6 : GETHOSTBYADDR;
  85
  86   return nscd_gethst_r (addr, len, reqtype, resultbuf, buffer, buflen, result,
  87                         h_errnop);
  88 }
  89
  90
  91 libc_locked_map_ptr (map_handle);
  92 /* Note that we only free the structure if necessary.  The memory
  93    mapping is not removed since it is not visible to the malloc
  94    handling.  */
  95 libc_freeres_fn (gr_map_free)
  96 {
  97
  98   if (map_handle.mapped != NO_MAPPING)
  99     free (map_handle.mapped);
 100 }
 101
 102
 103 static int
 104 internal_function
 105 nscd_gethst_r (const char *key, size_t keylen, request_type type,
 106                struct hostent *resultbuf, char *buffer, size_t buflen,
 107                struct hostent **result, int *h_errnop)
 108 {
 109   const hst_response_header *hst_resp = NULL;
 110   const char *h_name = NULL;
 111   const uint32_t *aliases_len = NULL;
 112   const char *addr_list = NULL;
 113   size_t addr_list_len = 0;
 114   int retval = -1;
 115   int gc_cycle;
 116   const char *recend = (const char *) ~UINTMAX_C (0);
 117   int sock = -1;
 118
 119   /* If the mapping is available, try to search there instead of
 120      communicating with the nscd.  */
 121   struct mapped_database *mapped = __nscd_get_map_ref (GETFDHST, "hosts",
 122                                                        &map_handle, &gc_cycle);
 123  retry:
 124   if (mapped != MAP_FAILED)
 125     {
 126       const struct datahead *found = __nscd_cache_search (type, key, keylen,
 127                                                           mapped);
 128       if (found != NULL)
 129         {
 130           hst_resp = &found->data[0].hstdata;
 131           h_name = (char *) (hst_resp + 1);
 132           aliases_len = (uint32_t *) (h_name + hst_resp->h_name_len);
 133           addr_list = ((char *) aliases_len
 134                        + hst_resp->h_aliases_cnt * sizeof (uint32_t));
 135           addr_list_len = hst_resp->h_addr_list_cnt * INADDRSZ;
 136
 137 #ifndef _STRING_ARCH_unaligned
 138           /* The aliases_len array in the mapped database might very
 139              well be unaligned.  We will access it word-wise so on
 140              platforms which do not tolerate unaligned accesses we
 141              need to make an aligned copy.  */
 142           if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))
 143               != 0)
 144             {
 145               uint32_t *tmp = alloca (hst_resp->h_aliases_cnt
 146                                       * sizeof (uint32_t));
 147               aliases_len = memcpy (tmp, aliases_len,
 148                                     hst_resp->h_aliases_cnt
 149                                     * sizeof (uint32_t));
 150             }
 151 #endif
 152           if (type != GETHOSTBYADDR && type != GETHOSTBYNAME)
 153             {
 154               if (hst_resp->h_length == INADDRSZ)
 155                 addr_list += addr_list_len;
 156               addr_list_len = hst_resp->h_addr_list_cnt * IN6ADDRSZ;
 157             }
 158           recend = (const char *) found->data + found->recsize;
 159           if (__builtin_expect ((const char *) addr_list + addr_list_len
 160                                 > recend, 0))
 161             goto out_close;
 162         }
 163     }
 164
 165   hst_response_header hst_resp_mem;
 166   if (hst_resp == NULL)
 167     {
 168       sock = __nscd_open_socket (key, keylen, type, &hst_resp_mem,
 169                                  sizeof (hst_resp_mem));
 170       if (sock == -1)
 171         {
 172           __nss_not_use_nscd_hosts = 1;
 173           goto out;;
 174         }
 175
 176       hst_resp = &hst_resp_mem;
 177     }
 178
 179   /* No value found so far.  */
 180   *result = NULL;
 181
 182   if (__builtin_expect (hst_resp->found == -1, 0))
 183     {
 184       /* The daemon does not cache this database.  */
 185       __nss_not_use_nscd_hosts = 1;
 186       goto out_close;
 187     }
 188
 189   if (hst_resp->found == 1)
 190     {
 191       struct iovec vec[4];
 192       char *cp = buffer;
 193       uintptr_t align1;
 194       uintptr_t align2;
 195       size_t total_len;
 196       ssize_t cnt;
 197       char *ignore;
 198       int n;
 199
 200       /* A first check whether the buffer is sufficiently large is possible.  */
 201       /* Now allocate the buffer the array for the group members.  We must
 202          align the pointer and the base of the h_addr_list pointers.  */
 203       align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))
 204                 & (__alignof__ (char *) - 1));
 205       align2 = ((__alignof__ (char *) - ((cp + align1 + hst_resp->h_name_len)
 206                                          - ((char *) 0)))
 207                 & (__alignof__ (char *) - 1));
 208       if (buflen < (align1 + hst_resp->h_name_len + align2
 209                     + ((hst_resp->h_aliases_cnt + hst_resp->h_addr_list_cnt
 210                         + 2)
 211                        * sizeof (char *))
 212                     + hst_resp->h_addr_list_cnt * (type == AF_INET
 213                                                    ? INADDRSZ : IN6ADDRSZ)))
 214         {
 215         no_room:
 216           __set_errno (ERANGE);
 217           retval = ERANGE;
 218           goto out_close;
 219         }
 220       cp += align1;
 221
 222       /* Prepare the result as far as we can.  */
 223       resultbuf->h_aliases = (char **) cp;
 224       cp += (hst_resp->h_aliases_cnt + 1) * sizeof (char *);
 225       resultbuf->h_addr_list = (char **) cp;
 226       cp += (hst_resp->h_addr_list_cnt + 1) * sizeof (char *);
 227
 228       resultbuf->h_name = cp;
 229       cp += hst_resp->h_name_len + align2;
 230
 231       if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
 232         {
 233           resultbuf->h_addrtype = AF_INET;
 234           resultbuf->h_length = INADDRSZ;
 235         }
 236       else
 237         {
 238           resultbuf->h_addrtype = AF_INET6;
 239           resultbuf->h_length = IN6ADDRSZ;
 240         }
 241       for (cnt = 0; cnt < hst_resp->h_addr_list_cnt; ++cnt)
 242         {
 243           resultbuf->h_addr_list[cnt] = cp;
 244           cp += resultbuf->h_length;
 245         }
 246       resultbuf->h_addr_list[cnt] = NULL;
 247
 248       if (h_name == NULL)
 249         {
 250           vec[0].iov_base = resultbuf->h_name;
 251           vec[0].iov_len = hst_resp->h_name_len;
 252           total_len = hst_resp->h_name_len;
 253           n = 1;
 254
 255           if (hst_resp->h_aliases_cnt > 0)
 256             {
 257               aliases_len = alloca (hst_resp->h_aliases_cnt
 258                                     * sizeof (uint32_t));
 259               vec[n].iov_base = (void *) aliases_len;
 260               vec[n].iov_len = hst_resp->h_aliases_cnt * sizeof (uint32_t);
 261
 262               total_len += hst_resp->h_aliases_cnt * sizeof (uint32_t);
 263               ++n;
 264             }
 265
 266           if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
 267             {
 268               vec[n].iov_base = resultbuf->h_addr_list[0];
 269               vec[n].iov_len = hst_resp->h_addr_list_cnt * INADDRSZ;
 270
 271               total_len += hst_resp->h_addr_list_cnt * INADDRSZ;
 272
 273               ++n;
 274             }
 275           else
 276             {
 277               if (hst_resp->h_length == INADDRSZ)
 278                 {
 279                   ignore = alloca (hst_resp->h_addr_list_cnt * INADDRSZ);
 280                   vec[n].iov_base = ignore;
 281                   vec[n].iov_len = hst_resp->h_addr_list_cnt * INADDRSZ;
 282
 283                   total_len += hst_resp->h_addr_list_cnt * INADDRSZ;
 284
 285                   ++n;
 286                 }
 287
 288               vec[n].iov_base = resultbuf->h_addr_list[0];
 289               vec[n].iov_len = hst_resp->h_addr_list_cnt * IN6ADDRSZ;
 290
 291               total_len += hst_resp->h_addr_list_cnt * IN6ADDRSZ;
 292
 293               ++n;
 294             }
 295
 296           if ((size_t) TEMP_FAILURE_RETRY (__readv (sock, vec, n))
 297               != total_len)
 298             goto out_close;
 299         }
 300       else
 301         {
 302           memcpy (resultbuf->h_name, h_name, hst_resp->h_name_len);
 303           memcpy (resultbuf->h_addr_list[0], addr_list, addr_list_len);
 304         }
 305
 306       /*  Now we also can read the aliases.  */
 307       total_len = 0;
 308       for (cnt = 0; cnt < hst_resp->h_aliases_cnt; ++cnt)
 309         {
 310           resultbuf->h_aliases[cnt] = cp;
 311           cp += aliases_len[cnt];
 312           total_len += aliases_len[cnt];
 313         }
 314       resultbuf->h_aliases[cnt] = NULL;
 315
 316       if (__builtin_expect ((const char *) addr_list + addr_list_len
 317                             + total_len > recend, 0))
 318         goto out_close;
 319       /* See whether this would exceed the buffer capacity.  */
 320       if (__builtin_expect (cp > buffer + buflen, 0))
 321         goto no_room;
 322
 323       /* And finally read the aliases.  */
 324       if (addr_list == NULL)
 325         {
 326           if ((size_t) TEMP_FAILURE_RETRY (__read (sock,
 327                                                    resultbuf->h_aliases[0],
 328                                                    total_len)) == total_len)
 329             {
 330               retval = 0;
 331               *result = resultbuf;
 332             }
 333         }
 334       else
 335         {
 336           memcpy (resultbuf->h_aliases[0],
 337                   (const char *) addr_list + addr_list_len, total_len);
 338
 339           retval = 0;
 340           *result = resultbuf;
 341         }
 342     }
 343   else
 344     {
 345       /* Store the error number.  */
 346       *h_errnop = hst_resp->error;
 347
 348       /* The `errno' to some value != ERANGE.  */
 349       __set_errno (ENOENT);
 350       /* Even though we have not found anything, the result is zero.  */
 351       retval = 0;
 352     }
 353
 354  out_close:
 355   if (sock != -1)
 356     close_not_cancel_no_status (sock);
 357  out:
 358   if (__nscd_drop_map_ref (mapped, gc_cycle) != 0)
 359     /* When we come here this means there has been a GC cycle while we
 360        were looking for the data.  This means the data might have been
 361        inconsistent.  Retry.  */
 362     goto retry;
 363
 364   return retval;
 365 }