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 <not-cancel.h>
  31
  32 #include "nscd-client.h"
  33 #include "nscd_proto.h"
  34
  35 int __nss_not_use_nscd_hosts;
  36
  37 static int nscd_gethst_r (const char *key, size_t keylen, request_type type,
  38                           struct hostent *resultbuf, char *buffer,
  39                           size_t buflen, struct hostent **result,
  40                           int *h_errnop) internal_function;
  41
  42
  43 int
  44 __nscd_gethostbyname_r (const char *name, struct hostent *resultbuf,
  45                         char *buffer, size_t buflen, struct hostent **result,
  46                         int *h_errnop)
  47 {
  48   request_type reqtype;
  49
  50   reqtype = (_res.options & RES_USE_INET6) ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
  51
  52   return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
  53                         buffer, buflen, result, h_errnop);
  54 }
  55
  56
  57 int
  58 __nscd_gethostbyname2_r (const char *name, int af, struct hostent *resultbuf,
  59                          char *buffer, size_t buflen, struct hostent **result,
  60                          int *h_errnop)
  61 {
  62   request_type reqtype;
  63
  64   reqtype = af == AF_INET6 ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
  65
  66   return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
  67                         buffer, buflen, result, h_errnop);
  68 }
  69
  70
  71 int
  72 __nscd_gethostbyaddr_r (const void *addr, socklen_t len, int type,
  73                         struct hostent *resultbuf, char *buffer, size_t buflen,
  74                         struct hostent **result, int *h_errnop)
  75 {
  76   request_type reqtype;
  77
  78   if (!((len == INADDRSZ && type == AF_INET)
  79         || (len == IN6ADDRSZ && type == AF_INET6)))
  80     /* LEN and TYPE do not match.  */
  81     return -1;
  82
  83   reqtype = type == AF_INET6 ? GETHOSTBYADDRv6 : GETHOSTBYADDR;
  84
  85   return nscd_gethst_r (addr, len, reqtype, resultbuf, buffer, buflen, result,
  86                         h_errnop);
  87 }
  88
  89
  90 libc_locked_map_ptr (map_handle);
  91 /* Note that we only free the structure if necessary.  The memory
  92    mapping is not removed since it is not visible to the malloc
  93    handling.  */
  94 libc_freeres_fn (gr_map_free)
  95 {
  96
  97   if (map_handle.mapped != NO_MAPPING)
  98     free (map_handle.mapped);
  99 }
 100
 101
 102 static int
 103 internal_function
 104 nscd_gethst_r (const char *key, size_t keylen, request_type type,
 105                struct hostent *resultbuf, char *buffer, size_t buflen,
 106                struct hostent **result, int *h_errnop)
 107 {
 108   int gc_cycle;
 109   int nretries = 0;
 110
 111   /* If the mapping is available, try to search there instead of
 112      communicating with the nscd.  */
 113   struct mapped_database *mapped;
 114   mapped = __nscd_get_map_ref (GETFDHST, "hosts", &map_handle, &gc_cycle);
 115
 116  retry:;
 117   const hst_response_header *hst_resp = NULL;
 118   const char *h_name = NULL;
 119   const uint32_t *aliases_len = NULL;
 120   const char *addr_list = NULL;
 121   size_t addr_list_len = 0;
 122   int retval = -1;
 123   const char *recend = (const char *) ~UINTMAX_C (0);
 124   int sock = -1;
 125   if (mapped != NO_MAPPING)
 126     {
 127       const struct datahead *found = __nscd_cache_search (type, key, keylen,
 128                                                           mapped);
 129       if (found != NULL)
 130         {
 131           hst_resp = &found->data[0].hstdata;
 132           h_name = (char *) (hst_resp + 1);
 133           aliases_len = (uint32_t *) (h_name + hst_resp->h_name_len);
 134           addr_list = ((char *) aliases_len
 135                        + hst_resp->h_aliases_cnt * sizeof (uint32_t));
 136           addr_list_len = hst_resp->h_addr_list_cnt * INADDRSZ;
 137
 138 #ifndef _STRING_ARCH_unaligned
 139           /* The aliases_len array in the mapped database might very
 140              well be unaligned.  We will access it word-wise so on
 141              platforms which do not tolerate unaligned accesses we
 142              need to make an aligned copy.  */
 143           if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))
 144               != 0)
 145             {
 146               uint32_t *tmp = alloca (hst_resp->h_aliases_cnt
 147                                       * sizeof (uint32_t));
 148               aliases_len = memcpy (tmp, aliases_len,
 149                                     hst_resp->h_aliases_cnt
 150                                     * sizeof (uint32_t));
 151             }
 152 #endif
 153           if (type != GETHOSTBYADDR && type != GETHOSTBYNAME)
 154             {
 155               if (hst_resp->h_length == INADDRSZ)
 156                 addr_list += addr_list_len;
 157               addr_list_len = hst_resp->h_addr_list_cnt * IN6ADDRSZ;
 158             }
 159           recend = (const char *) found->data + found->recsize;
 160           if (__builtin_expect ((const char *) addr_list + addr_list_len
 161                                 > recend, 0))
 162             goto out_close;
 163         }
 164     }
 165
 166   hst_response_header hst_resp_mem;
 167   if (hst_resp == NULL)
 168     {
 169       sock = __nscd_open_socket (key, keylen, type, &hst_resp_mem,
 170                                  sizeof (hst_resp_mem));
 171       if (sock == -1)
 172         {
 173           __nss_not_use_nscd_hosts = 1;
 174           goto out;;
 175         }
 176
 177       hst_resp = &hst_resp_mem;
 178     }
 179
 180   /* No value found so far.  */
 181   *result = NULL;
 182
 183   if (__builtin_expect (hst_resp->found == -1, 0))
 184     {
 185       /* The daemon does not cache this database.  */
 186       __nss_not_use_nscd_hosts = 1;
 187       goto out_close;
 188     }
 189
 190   if (hst_resp->found == 1)
 191     {
 192       struct iovec vec[4];
 193       char *cp = buffer;
 194       uintptr_t align1;
 195       uintptr_t align2;
 196       size_t total_len;
 197       ssize_t cnt;
 198       char *ignore;
 199       int n;
 200
 201       /* A first check whether the buffer is sufficiently large is possible.  */
 202       /* Now allocate the buffer the array for the group members.  We must
 203          align the pointer and the base of the h_addr_list pointers.  */
 204       align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))
 205                 & (__alignof__ (char *) - 1));
 206       align2 = ((__alignof__ (char *) - ((cp + align1 + hst_resp->h_name_len)
 207                                          - ((char *) 0)))
 208                 & (__alignof__ (char *) - 1));
 209       if (buflen < (align1 + hst_resp->h_name_len + align2
 210                     + ((hst_resp->h_aliases_cnt + hst_resp->h_addr_list_cnt
 211                         + 2)
 212                        * sizeof (char *))
 213                     + hst_resp->h_addr_list_cnt * (type == AF_INET
 214                                                    ? INADDRSZ : IN6ADDRSZ)))
 215         {
 216         no_room:
 217           __set_errno (ERANGE);
 218           retval = ERANGE;
 219           goto out_close;
 220         }
 221       cp += align1;
 222
 223       /* Prepare the result as far as we can.  */
 224       resultbuf->h_aliases = (char **) cp;
 225       cp += (hst_resp->h_aliases_cnt + 1) * sizeof (char *);
 226       resultbuf->h_addr_list = (char **) cp;
 227       cp += (hst_resp->h_addr_list_cnt + 1) * sizeof (char *);
 228
 229       resultbuf->h_name = cp;
 230       cp += hst_resp->h_name_len + align2;
 231
 232       if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
 233         {
 234           resultbuf->h_addrtype = AF_INET;
 235           resultbuf->h_length = INADDRSZ;
 236         }
 237       else
 238         {
 239           resultbuf->h_addrtype = AF_INET6;
 240           resultbuf->h_length = IN6ADDRSZ;
 241         }
 242       for (cnt = 0; cnt < hst_resp->h_addr_list_cnt; ++cnt)
 243         {
 244           resultbuf->h_addr_list[cnt] = cp;
 245           cp += resultbuf->h_length;
 246         }
 247       resultbuf->h_addr_list[cnt] = NULL;
 248
 249       if (h_name == NULL)
 250         {
 251           vec[0].iov_base = resultbuf->h_name;
 252           vec[0].iov_len = hst_resp->h_name_len;
 253           total_len = hst_resp->h_name_len;
 254           n = 1;
 255
 256           if (hst_resp->h_aliases_cnt > 0)
 257             {
 258               aliases_len = alloca (hst_resp->h_aliases_cnt
 259                                     * sizeof (uint32_t));
 260               vec[n].iov_base = (void *) aliases_len;
 261               vec[n].iov_len = hst_resp->h_aliases_cnt * sizeof (uint32_t);
 262
 263               total_len += hst_resp->h_aliases_cnt * sizeof (uint32_t);
 264               ++n;
 265             }
 266
 267           if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
 268             {
 269               vec[n].iov_base = resultbuf->h_addr_list[0];
 270               vec[n].iov_len = hst_resp->h_addr_list_cnt * INADDRSZ;
 271
 272               total_len += hst_resp->h_addr_list_cnt * INADDRSZ;
 273
 274               ++n;
 275             }
 276           else
 277             {
 278               if (hst_resp->h_length == INADDRSZ)
 279                 {
 280                   ignore = alloca (hst_resp->h_addr_list_cnt * INADDRSZ);
 281                   vec[n].iov_base = ignore;
 282                   vec[n].iov_len = hst_resp->h_addr_list_cnt * INADDRSZ;
 283
 284                   total_len += hst_resp->h_addr_list_cnt * INADDRSZ;
 285
 286                   ++n;
 287                 }
 288
 289               vec[n].iov_base = resultbuf->h_addr_list[0];
 290               vec[n].iov_len = hst_resp->h_addr_list_cnt * IN6ADDRSZ;
 291
 292               total_len += hst_resp->h_addr_list_cnt * IN6ADDRSZ;
 293
 294               ++n;
 295             }
 296
 297           if ((size_t) TEMP_FAILURE_RETRY (__readv (sock, vec, n))
 298               != total_len)
 299             goto out_close;
 300         }
 301       else
 302         {
 303           memcpy (resultbuf->h_name, h_name, hst_resp->h_name_len);
 304           memcpy (resultbuf->h_addr_list[0], addr_list, addr_list_len);
 305         }
 306
 307       /*  Now we also can read the aliases.  */
 308       total_len = 0;
 309       for (cnt = 0; cnt < hst_resp->h_aliases_cnt; ++cnt)
 310         {
 311           resultbuf->h_aliases[cnt] = cp;
 312           cp += aliases_len[cnt];
 313           total_len += aliases_len[cnt];
 314         }
 315       resultbuf->h_aliases[cnt] = NULL;
 316
 317       if (__builtin_expect ((const char *) addr_list + addr_list_len
 318                             + total_len > recend, 0))
 319         goto out_close;
 320       /* See whether this would exceed the buffer capacity.  */
 321       if (__builtin_expect (cp > buffer + buflen, 0))
 322         goto no_room;
 323
 324       /* And finally read the aliases.  */
 325       if (addr_list == NULL)
 326         {
 327           if ((size_t) TEMP_FAILURE_RETRY (__read (sock,
 328                                                    resultbuf->h_aliases[0],
 329                                                    total_len)) == total_len)
 330             {
 331               retval = 0;
 332               *result = resultbuf;
 333             }
 334         }
 335       else
 336         {
 337           memcpy (resultbuf->h_aliases[0],
 338                   (const char *) addr_list + addr_list_len, total_len);
 339
 340           retval = 0;
 341           *result = resultbuf;
 342         }
 343     }
 344   else
 345     {
 346       /* Store the error number.  */
 347       *h_errnop = hst_resp->error;
 348
 349       /* The `errno' to some value != ERANGE.  */
 350       __set_errno (ENOENT);
 351       /* Even though we have not found anything, the result is zero.  */
 352       retval = 0;
 353     }
 354
 355  out_close:
 356   if (sock != -1)
 357     close_not_cancel_no_status (sock);
 358  out:
 359   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
 360     {
 361       /* When we come here this means there has been a GC cycle while we
 362          were looking for the data.  This means the data might have been
 363          inconsistent.  Retry if possible.  */
 364       if ((gc_cycle & 1) != 0 || ++nretries == 5)
 365         {
 366           /* nscd is just running gc now.  Disable using the mapping.  */
 367           __nscd_unmap (mapped);
 368           mapped = NO_MAPPING;
 369         }
 370
 371       goto retry;
 372     }
 373
 374   return retval;
 375 }