nscd/nscd_gethst_r.c

   1 /* Copyright (C) 1998-2005, 2006 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 (, __hst_map_handle) attribute_hidden;
  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 (hst_map_free)
  95 {
  96   if (__hst_map_handle.mapped != NO_MAPPING)
  97     {
  98       void *p = __hst_map_handle.mapped;
  99       __hst_map_handle.mapped = NO_MAPPING;
 100       free (p);
 101     }
 102 }
 103
 104
 105 static int
 106 internal_function
 107 nscd_gethst_r (const char *key, size_t keylen, request_type type,
 108                struct hostent *resultbuf, char *buffer, size_t buflen,
 109                struct hostent **result, int *h_errnop)
 110 {
 111   int gc_cycle;
 112   int nretries = 0;
 113
 114   /* If the mapping is available, try to search there instead of
 115      communicating with the nscd.  */
 116   struct mapped_database *mapped;
 117   mapped = __nscd_get_map_ref (GETFDHST, "hosts", &__hst_map_handle,
 118                                &gc_cycle);
 119
 120  retry:;
 121   const hst_response_header *hst_resp = NULL;
 122   const char *h_name = NULL;
 123   const uint32_t *aliases_len = NULL;
 124   const char *addr_list = NULL;
 125   size_t addr_list_len = 0;
 126   int retval = -1;
 127   const char *recend = (const char *) ~UINTMAX_C (0);
 128   int sock = -1;
 129   if (mapped != NO_MAPPING)
 130     {
 131       const struct datahead *found = __nscd_cache_search (type, key, keylen,
 132                                                           mapped);
 133       if (found != NULL)
 134         {
 135           hst_resp = &found->data[0].hstdata;
 136           h_name = (char *) (hst_resp + 1);
 137           aliases_len = (uint32_t *) (h_name + hst_resp->h_name_len);
 138           addr_list = ((char *) aliases_len
 139                        + hst_resp->h_aliases_cnt * sizeof (uint32_t));
 140           addr_list_len = hst_resp->h_addr_list_cnt * INADDRSZ;
 141
 142 #ifndef _STRING_ARCH_unaligned
 143           /* The aliases_len array in the mapped database might very
 144              well be unaligned.  We will access it word-wise so on
 145              platforms which do not tolerate unaligned accesses we
 146              need to make an aligned copy.  */
 147           if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))
 148               != 0)
 149             {
 150               uint32_t *tmp = alloca (hst_resp->h_aliases_cnt
 151                                       * sizeof (uint32_t));
 152               aliases_len = memcpy (tmp, aliases_len,
 153                                     hst_resp->h_aliases_cnt
 154                                     * sizeof (uint32_t));
 155             }
 156 #endif
 157           if (type != GETHOSTBYADDR && type != GETHOSTBYNAME)
 158             {
 159               if (hst_resp->h_length == INADDRSZ)
 160                 addr_list += addr_list_len;
 161               addr_list_len = hst_resp->h_addr_list_cnt * IN6ADDRSZ;
 162             }
 163           recend = (const char *) found->data + found->recsize;
 164           if (__builtin_expect ((const char *) addr_list + addr_list_len
 165                                 > recend, 0))
 166             goto out_close;
 167         }
 168     }
 169
 170   hst_response_header hst_resp_mem;
 171   if (hst_resp == NULL)
 172     {
 173       sock = __nscd_open_socket (key, keylen, type, &hst_resp_mem,
 174                                  sizeof (hst_resp_mem));
 175       if (sock == -1)
 176         {
 177           __nss_not_use_nscd_hosts = 1;
 178           goto out;;
 179         }
 180
 181       hst_resp = &hst_resp_mem;
 182     }
 183
 184   /* No value found so far.  */
 185   *result = NULL;
 186
 187   if (__builtin_expect (hst_resp->found == -1, 0))
 188     {
 189       /* The daemon does not cache this database.  */
 190       __nss_not_use_nscd_hosts = 1;
 191       goto out_close;
 192     }
 193
 194   if (hst_resp->found == 1)
 195     {
 196       struct iovec vec[4];
 197       char *cp = buffer;
 198       uintptr_t align1;
 199       uintptr_t align2;
 200       size_t total_len;
 201       ssize_t cnt;
 202       char *ignore;
 203       int n;
 204
 205       /* A first check whether the buffer is sufficiently large is possible.  */
 206       /* Now allocate the buffer the array for the group members.  We must
 207          align the pointer and the base of the h_addr_list pointers.  */
 208       align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))
 209                 & (__alignof__ (char *) - 1));
 210       align2 = ((__alignof__ (char *) - ((cp + align1 + hst_resp->h_name_len)
 211                                          - ((char *) 0)))
 212                 & (__alignof__ (char *) - 1));
 213       if (buflen < (align1 + hst_resp->h_name_len + align2
 214                     + ((hst_resp->h_aliases_cnt + hst_resp->h_addr_list_cnt
 215                         + 2)
 216                        * sizeof (char *))
 217                     + hst_resp->h_addr_list_cnt * (type == AF_INET
 218                                                    ? INADDRSZ : IN6ADDRSZ)))
 219         {
 220         no_room:
 221           *h_errnop = NETDB_INTERNAL;
 222           __set_errno (ERANGE);
 223           retval = ERANGE;
 224           goto out_close;
 225         }
 226       cp += align1;
 227
 228       /* Prepare the result as far as we can.  */
 229       resultbuf->h_aliases = (char **) cp;
 230       cp += (hst_resp->h_aliases_cnt + 1) * sizeof (char *);
 231       resultbuf->h_addr_list = (char **) cp;
 232       cp += (hst_resp->h_addr_list_cnt + 1) * sizeof (char *);
 233
 234       resultbuf->h_name = cp;
 235       cp += hst_resp->h_name_len + align2;
 236
 237       if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
 238         {
 239           resultbuf->h_addrtype = AF_INET;
 240           resultbuf->h_length = INADDRSZ;
 241         }
 242       else
 243         {
 244           resultbuf->h_addrtype = AF_INET6;
 245           resultbuf->h_length = IN6ADDRSZ;
 246         }
 247       for (cnt = 0; cnt < hst_resp->h_addr_list_cnt; ++cnt)
 248         {
 249           resultbuf->h_addr_list[cnt] = cp;
 250           cp += resultbuf->h_length;
 251         }
 252       resultbuf->h_addr_list[cnt] = NULL;
 253
 254       if (h_name == NULL)
 255         {
 256           vec[0].iov_base = resultbuf->h_name;
 257           vec[0].iov_len = hst_resp->h_name_len;
 258           total_len = hst_resp->h_name_len;
 259           n = 1;
 260
 261           if (hst_resp->h_aliases_cnt > 0)
 262             {
 263               aliases_len = alloca (hst_resp->h_aliases_cnt
 264                                     * sizeof (uint32_t));
 265               vec[n].iov_base = (void *) aliases_len;
 266               vec[n].iov_len = hst_resp->h_aliases_cnt * sizeof (uint32_t);
 267
 268               total_len += hst_resp->h_aliases_cnt * sizeof (uint32_t);
 269               ++n;
 270             }
 271
 272           if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
 273             {
 274               vec[n].iov_base = resultbuf->h_addr_list[0];
 275               vec[n].iov_len = hst_resp->h_addr_list_cnt * INADDRSZ;
 276
 277               total_len += hst_resp->h_addr_list_cnt * INADDRSZ;
 278
 279               ++n;
 280             }
 281           else
 282             {
 283               if (hst_resp->h_length == INADDRSZ)
 284                 {
 285                   ignore = alloca (hst_resp->h_addr_list_cnt * INADDRSZ);
 286                   vec[n].iov_base = ignore;
 287                   vec[n].iov_len = hst_resp->h_addr_list_cnt * INADDRSZ;
 288
 289                   total_len += hst_resp->h_addr_list_cnt * INADDRSZ;
 290
 291                   ++n;
 292                 }
 293
 294               vec[n].iov_base = resultbuf->h_addr_list[0];
 295               vec[n].iov_len = hst_resp->h_addr_list_cnt * IN6ADDRSZ;
 296
 297               total_len += hst_resp->h_addr_list_cnt * IN6ADDRSZ;
 298
 299               ++n;
 300             }
 301
 302           if ((size_t) __readvall (sock, vec, n) != total_len)
 303             goto out_close;
 304         }
 305       else
 306         {
 307           memcpy (resultbuf->h_name, h_name, hst_resp->h_name_len);
 308           memcpy (resultbuf->h_addr_list[0], addr_list, addr_list_len);
 309         }
 310
 311       /*  Now we also can read the aliases.  */
 312       total_len = 0;
 313       for (cnt = 0; cnt < hst_resp->h_aliases_cnt; ++cnt)
 314         {
 315           resultbuf->h_aliases[cnt] = cp;
 316           cp += aliases_len[cnt];
 317           total_len += aliases_len[cnt];
 318         }
 319       resultbuf->h_aliases[cnt] = NULL;
 320
 321       if (__builtin_expect ((const char *) addr_list + addr_list_len
 322                             + total_len > recend, 0))
 323         goto out_close;
 324       /* See whether this would exceed the buffer capacity.  */
 325       if (__builtin_expect (cp > buffer + buflen, 0))
 326         goto no_room;
 327
 328       /* And finally read the aliases.  */
 329       if (addr_list == NULL)
 330         {
 331           if (total_len == 0
 332               || ((size_t) __readall (sock, resultbuf->h_aliases[0], total_len)
 333                   == total_len))
 334             {
 335               retval = 0;
 336               *result = resultbuf;
 337             }
 338         }
 339       else
 340         {
 341           memcpy (resultbuf->h_aliases[0],
 342                   (const char *) addr_list + addr_list_len, total_len);
 343
 344           /* Try to detect corrupt databases.  */
 345           if (resultbuf->h_name[hst_resp->h_name_len - 1] != '\0'
 346               || ({for (cnt = 0; cnt < hst_resp->h_aliases_cnt; ++cnt)
 347                      if (resultbuf->h_aliases[cnt][aliases_len[cnt] - 1]
 348                          != '\0')
 349                        break;
 350                    cnt < hst_resp->h_aliases_cnt; }))
 351             /* We cannot use the database.  */
 352             goto out_close;
 353
 354           retval = 0;
 355           *result = resultbuf;
 356         }
 357     }
 358   else
 359     {
 360       /* Store the error number.  */
 361       *h_errnop = hst_resp->error;
 362
 363       /* The `errno' to some value != ERANGE.  */
 364       __set_errno (ENOENT);
 365       /* Even though we have not found anything, the result is zero.  */
 366       retval = 0;
 367     }
 368
 369  out_close:
 370   if (sock != -1)
 371     close_not_cancel_no_status (sock);
 372  out:
 373   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
 374     {
 375       /* When we come here this means there has been a GC cycle while we
 376          were looking for the data.  This means the data might have been
 377          inconsistent.  Retry if possible.  */
 378       if ((gc_cycle & 1) != 0 || ++nretries == 5)
 379         {
 380           /* nscd is just running gc now.  Disable using the mapping.  */
 381           __nscd_unmap (mapped);
 382           mapped = NO_MAPPING;
 383         }
 384
 385       goto retry;
 386     }
 387
 388   return retval;
 389 }