nscd/nscd_gethst_r.c

   1 /* Copyright (C) 1998-2005, 2006, 2007, 2008, 2009, 2011
   2    Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <errno.h>
  22 #include <resolv.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <arpa/nameser.h>
  26 #include <not-cancel.h>
  27
  28 #include "nscd-client.h"
  29 #include "nscd_proto.h"
  30
  31 int __nss_not_use_nscd_hosts;
  32
  33 static int nscd_gethst_r (const char *key, size_t keylen, request_type type,
  34                           struct hostent *resultbuf, char *buffer,
  35                           size_t buflen, struct hostent **result,
  36                           int *h_errnop) internal_function;
  37
  38
  39 int
  40 __nscd_gethostbyname_r (const char *name, struct hostent *resultbuf,
  41                         char *buffer, size_t buflen, struct hostent **result,
  42                         int *h_errnop)
  43 {
  44   request_type reqtype;
  45
  46   reqtype = (_res.options & RES_USE_INET6) ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
  47
  48   return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
  49                         buffer, buflen, result, h_errnop);
  50 }
  51
  52
  53 int
  54 __nscd_gethostbyname2_r (const char *name, int af, struct hostent *resultbuf,
  55                          char *buffer, size_t buflen, struct hostent **result,
  56                          int *h_errnop)
  57 {
  58   request_type reqtype;
  59
  60   reqtype = af == AF_INET6 ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
  61
  62   return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
  63                         buffer, buflen, result, h_errnop);
  64 }
  65
  66
  67 int
  68 __nscd_gethostbyaddr_r (const void *addr, socklen_t len, int type,
  69                         struct hostent *resultbuf, char *buffer, size_t buflen,
  70                         struct hostent **result, int *h_errnop)
  71 {
  72   request_type reqtype;
  73
  74   if (!((len == INADDRSZ && type == AF_INET)
  75         || (len == IN6ADDRSZ && type == AF_INET6)))
  76     /* LEN and TYPE do not match.  */
  77     return -1;
  78
  79   reqtype = type == AF_INET6 ? GETHOSTBYADDRv6 : GETHOSTBYADDR;
  80
  81   return nscd_gethst_r (addr, len, reqtype, resultbuf, buffer, buflen, result,
  82                         h_errnop);
  83 }
  84
  85
  86 libc_locked_map_ptr (, __hst_map_handle) attribute_hidden;
  87 /* Note that we only free the structure if necessary.  The memory
  88    mapping is not removed since it is not visible to the malloc
  89    handling.  */
  90 libc_freeres_fn (hst_map_free)
  91 {
  92   if (__hst_map_handle.mapped != NO_MAPPING)
  93     {
  94       void *p = __hst_map_handle.mapped;
  95       __hst_map_handle.mapped = NO_MAPPING;
  96       free (p);
  97     }
  98 }
  99
 100
 101 uint32_t
 102 __nscd_get_nl_timestamp (void)
 103 {
 104   if (__nss_not_use_nscd_hosts != 0)
 105     return 0;
 106
 107   struct mapped_database *map = __hst_map_handle.mapped;
 108
 109   if (map == NULL
 110       || (map != NO_MAPPING
 111           && map->head->nscd_certainly_running == 0
 112           && map->head->timestamp + MAPPING_TIMEOUT < time (NULL)))
 113     map = __nscd_get_mapping (GETFDHST, "hosts", &__hst_map_handle.mapped);
 114
 115   if (map == NO_MAPPING)
 116     return 0;
 117
 118   return map->head->extra_data[NSCD_HST_IDX_CONF_TIMESTAMP];
 119 }
 120
 121
 122 int __nss_have_localdomain attribute_hidden;
 123
 124 static int
 125 internal_function
 126 nscd_gethst_r (const char *key, size_t keylen, request_type type,
 127                struct hostent *resultbuf, char *buffer, size_t buflen,
 128                struct hostent **result, int *h_errnop)
 129 {
 130   if (__builtin_expect (__nss_have_localdomain >= 0, 0))
 131     {
 132       if (__nss_have_localdomain == 0)
 133         __nss_have_localdomain = getenv ("LOCALDOMAIN") != NULL ? 1 : -1;
 134       if (__nss_have_localdomain > 0)
 135         {
 136           __nss_not_use_nscd_hosts = 1;
 137           return -1;
 138         }
 139     }
 140
 141   int gc_cycle;
 142   int nretries = 0;
 143
 144   /* If the mapping is available, try to search there instead of
 145      communicating with the nscd.  */
 146   struct mapped_database *mapped;
 147   mapped = __nscd_get_map_ref (GETFDHST, "hosts", &__hst_map_handle,
 148                                &gc_cycle);
 149
 150  retry:;
 151   const char *h_name = NULL;
 152   const uint32_t *aliases_len = NULL;
 153   const char *addr_list = NULL;
 154   size_t addr_list_len = 0;
 155   int retval = -1;
 156   const char *recend = (const char *) ~UINTMAX_C (0);
 157   int sock = -1;
 158   hst_response_header hst_resp;
 159   if (mapped != NO_MAPPING)
 160     {
 161       /* No const qualifier, as it can change during garbage collection.  */
 162       struct datahead *found = __nscd_cache_search (type, key, keylen, mapped,
 163                                                     sizeof hst_resp);
 164       if (found != NULL)
 165         {
 166           h_name = (char *) (&found->data[0].hstdata + 1);
 167           hst_resp = found->data[0].hstdata;
 168           aliases_len = (uint32_t *) (h_name + hst_resp.h_name_len);
 169           addr_list = ((char *) aliases_len
 170                        + hst_resp.h_aliases_cnt * sizeof (uint32_t));
 171           addr_list_len = hst_resp.h_addr_list_cnt * INADDRSZ;
 172           recend = (const char *) found->data + found->recsize;
 173           /* Now check if we can trust hst_resp fields.  If GC is
 174              in progress, it can contain anything.  */
 175           if (mapped->head->gc_cycle != gc_cycle)
 176             {
 177               retval = -2;
 178               goto out;
 179             }
 180
 181 #ifndef _STRING_ARCH_unaligned
 182           /* The aliases_len array in the mapped database might very
 183              well be unaligned.  We will access it word-wise so on
 184              platforms which do not tolerate unaligned accesses we
 185              need to make an aligned copy.  */
 186           if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))
 187               != 0)
 188             {
 189               uint32_t *tmp = alloca (hst_resp.h_aliases_cnt
 190                                       * sizeof (uint32_t));
 191               aliases_len = memcpy (tmp, aliases_len,
 192                                     hst_resp.h_aliases_cnt
 193                                     * sizeof (uint32_t));
 194             }
 195 #endif
 196           if (type != GETHOSTBYADDR && type != GETHOSTBYNAME)
 197             {
 198               if (hst_resp.h_length == INADDRSZ)
 199                 addr_list += addr_list_len;
 200               addr_list_len = hst_resp.h_addr_list_cnt * IN6ADDRSZ;
 201             }
 202           if (__builtin_expect ((const char *) addr_list + addr_list_len
 203                                 > recend, 0))
 204             goto out;
 205         }
 206     }
 207
 208   if (h_name == NULL)
 209     {
 210       sock = __nscd_open_socket (key, keylen, type, &hst_resp,
 211                                  sizeof (hst_resp));
 212       if (sock == -1)
 213         {
 214           __nss_not_use_nscd_hosts = 1;
 215           goto out;
 216         }
 217     }
 218
 219   /* No value found so far.  */
 220   *result = NULL;
 221
 222   if (__builtin_expect (hst_resp.found == -1, 0))
 223     {
 224       /* The daemon does not cache this database.  */
 225       __nss_not_use_nscd_hosts = 1;
 226       goto out_close;
 227     }
 228
 229   if (hst_resp.found == 1)
 230     {
 231       char *cp = buffer;
 232       uintptr_t align1;
 233       uintptr_t align2;
 234       size_t total_len;
 235       ssize_t cnt;
 236       char *ignore;
 237       int n;
 238
 239       /* A first check whether the buffer is sufficiently large is possible.  */
 240       /* Now allocate the buffer the array for the group members.  We must
 241          align the pointer and the base of the h_addr_list pointers.  */
 242       align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))
 243                 & (__alignof__ (char *) - 1));
 244       align2 = ((__alignof__ (char *) - ((cp + align1 + hst_resp.h_name_len)
 245                                          - ((char *) 0)))
 246                 & (__alignof__ (char *) - 1));
 247       if (buflen < (align1 + hst_resp.h_name_len + align2
 248                     + ((hst_resp.h_aliases_cnt + hst_resp.h_addr_list_cnt
 249                         + 2)
 250                        * sizeof (char *))
 251                     + hst_resp.h_addr_list_cnt * (type == AF_INET
 252                                                   ? INADDRSZ : IN6ADDRSZ)))
 253         {
 254         no_room:
 255           *h_errnop = NETDB_INTERNAL;
 256           __set_errno (ERANGE);
 257           retval = ERANGE;
 258           goto out_close;
 259         }
 260       cp += align1;
 261
 262       /* Prepare the result as far as we can.  */
 263       resultbuf->h_aliases = (char **) cp;
 264       cp += (hst_resp.h_aliases_cnt + 1) * sizeof (char *);
 265       resultbuf->h_addr_list = (char **) cp;
 266       cp += (hst_resp.h_addr_list_cnt + 1) * sizeof (char *);
 267
 268       resultbuf->h_name = cp;
 269       cp += hst_resp.h_name_len + align2;
 270
 271       if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
 272         {
 273           resultbuf->h_addrtype = AF_INET;
 274           resultbuf->h_length = INADDRSZ;
 275         }
 276       else
 277         {
 278           resultbuf->h_addrtype = AF_INET6;
 279           resultbuf->h_length = IN6ADDRSZ;
 280         }
 281       for (cnt = 0; cnt < hst_resp.h_addr_list_cnt; ++cnt)
 282         {
 283           resultbuf->h_addr_list[cnt] = cp;
 284           cp += resultbuf->h_length;
 285         }
 286       resultbuf->h_addr_list[cnt] = NULL;
 287
 288       if (h_name == NULL)
 289         {
 290           struct iovec vec[4];
 291
 292           vec[0].iov_base = resultbuf->h_name;
 293           vec[0].iov_len = hst_resp.h_name_len;
 294           total_len = hst_resp.h_name_len;
 295           n = 1;
 296
 297           if (hst_resp.h_aliases_cnt > 0)
 298             {
 299               aliases_len = alloca (hst_resp.h_aliases_cnt
 300                                     * sizeof (uint32_t));
 301               vec[n].iov_base = (void *) aliases_len;
 302               vec[n].iov_len = hst_resp.h_aliases_cnt * sizeof (uint32_t);
 303
 304               total_len += hst_resp.h_aliases_cnt * sizeof (uint32_t);
 305               ++n;
 306             }
 307
 308           if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
 309             {
 310               vec[n].iov_base = resultbuf->h_addr_list[0];
 311               vec[n].iov_len = hst_resp.h_addr_list_cnt * INADDRSZ;
 312
 313               total_len += hst_resp.h_addr_list_cnt * INADDRSZ;
 314
 315               ++n;
 316             }
 317           else
 318             {
 319               if (hst_resp.h_length == INADDRSZ)
 320                 {
 321                   ignore = alloca (hst_resp.h_addr_list_cnt * INADDRSZ);
 322                   vec[n].iov_base = ignore;
 323                   vec[n].iov_len = hst_resp.h_addr_list_cnt * INADDRSZ;
 324
 325                   total_len += hst_resp.h_addr_list_cnt * INADDRSZ;
 326
 327                   ++n;
 328                 }
 329
 330               vec[n].iov_base = resultbuf->h_addr_list[0];
 331               vec[n].iov_len = hst_resp.h_addr_list_cnt * IN6ADDRSZ;
 332
 333               total_len += hst_resp.h_addr_list_cnt * IN6ADDRSZ;
 334
 335               ++n;
 336             }
 337
 338           if ((size_t) __readvall (sock, vec, n) != total_len)
 339             goto out_close;
 340         }
 341       else
 342         {
 343           memcpy (resultbuf->h_name, h_name, hst_resp.h_name_len);
 344           memcpy (resultbuf->h_addr_list[0], addr_list, addr_list_len);
 345         }
 346
 347       /*  Now we also can read the aliases.  */
 348       total_len = 0;
 349       for (cnt = 0; cnt < hst_resp.h_aliases_cnt; ++cnt)
 350         {
 351           resultbuf->h_aliases[cnt] = cp;
 352           cp += aliases_len[cnt];
 353           total_len += aliases_len[cnt];
 354         }
 355       resultbuf->h_aliases[cnt] = NULL;
 356
 357       if (__builtin_expect ((const char *) addr_list + addr_list_len
 358                             + total_len > recend, 0))
 359         {
 360           /* aliases_len array might contain garbage during nscd GC cycle,
 361              retry rather than fail in that case.  */
 362           if (addr_list != NULL && mapped->head->gc_cycle != gc_cycle)
 363             retval = -2;
 364           goto out_close;
 365         }
 366       /* See whether this would exceed the buffer capacity.  */
 367       if (__builtin_expect (cp > buffer + buflen, 0))
 368         {
 369           /* aliases_len array might contain garbage during nscd GC cycle,
 370              retry rather than fail in that case.  */
 371           if (addr_list != NULL && mapped->head->gc_cycle != gc_cycle)
 372             {
 373               retval = -2;
 374               goto out_close;
 375             }
 376           goto no_room;
 377         }
 378
 379       /* And finally read the aliases.  */
 380       if (addr_list == NULL)
 381         {
 382           if (total_len == 0
 383               || ((size_t) __readall (sock, resultbuf->h_aliases[0], total_len)
 384                   == total_len))
 385             {
 386               retval = 0;
 387               *result = resultbuf;
 388             }
 389         }
 390       else
 391         {
 392           memcpy (resultbuf->h_aliases[0],
 393                   (const char *) addr_list + addr_list_len, total_len);
 394
 395           /* Try to detect corrupt databases.  */
 396           if (resultbuf->h_name[hst_resp.h_name_len - 1] != '\0'
 397               || ({for (cnt = 0; cnt < hst_resp.h_aliases_cnt; ++cnt)
 398                      if (resultbuf->h_aliases[cnt][aliases_len[cnt] - 1]
 399                          != '\0')
 400                        break;
 401                    cnt < hst_resp.h_aliases_cnt; }))
 402             {
 403               /* We cannot use the database.  */
 404               if (mapped->head->gc_cycle != gc_cycle)
 405                 retval = -2;
 406               goto out_close;
 407             }
 408
 409           retval = 0;
 410           *result = resultbuf;
 411         }
 412     }
 413   else
 414     {
 415       /* Store the error number.  */
 416       *h_errnop = hst_resp.error;
 417
 418       /* Set errno to 0 to indicate no error, just no found record.  */
 419       __set_errno (0);
 420       /* Even though we have not found anything, the result is zero.  */
 421       retval = 0;
 422     }
 423
 424  out_close:
 425   if (sock != -1)
 426     close_not_cancel_no_status (sock);
 427  out:
 428   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
 429     {
 430       /* When we come here this means there has been a GC cycle while we
 431          were looking for the data.  This means the data might have been
 432          inconsistent.  Retry if possible.  */
 433       if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 434         {
 435           /* nscd is just running gc now.  Disable using the mapping.  */
 436           if (atomic_decrement_val (&mapped->counter) == 0)
 437             __nscd_unmap (mapped);
 438           mapped = NO_MAPPING;
 439         }
 440
 441       if (retval != -1)
 442         goto retry;
 443     }
 444
 445   return retval;
 446 }