nscd/hstcache.c

   1 /* Cache handling for host lookup.
   2    Copyright (C) 1998, 1999, 2000 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 Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <assert.h>
  22 #include <errno.h>
  23 #include <error.h>
  24 #include <netdb.h>
  25 #include <stddef.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <time.h>
  30 #include <unistd.h>
  31 #include <libintl.h>
  32 #include <arpa/inet.h>
  33 #include <arpa/nameser.h>
  34
  35 #include "nscd.h"
  36 #include "dbg_log.h"
  37
  38
  39 /* This is the standard reply in case the service is disabled.  */
  40 static const hst_response_header disabled =
  41 {
  42   version: NSCD_VERSION,
  43   found: -1,
  44   h_name_len: 0,
  45   h_aliases_cnt: 0,
  46   h_addrtype: -1,
  47   h_length: -1,
  48   h_addr_list_cnt: 0,
  49   error: NETDB_INTERNAL
  50 };
  51
  52 /* This is the struct describing how to write this record.  */
  53 const struct iovec hst_iov_disabled =
  54 {
  55   iov_base: (void *) &disabled,
  56   iov_len: sizeof (disabled)
  57 };
  58
  59
  60 /* This is the standard reply in case we haven't found the dataset.  */
  61 static const hst_response_header notfound =
  62 {
  63   version: NSCD_VERSION,
  64   found: 0,
  65   h_name_len: 0,
  66   h_aliases_cnt: 0,
  67   h_addrtype: -1,
  68   h_length: -1,
  69   h_addr_list_cnt: 0,
  70   error: HOST_NOT_FOUND
  71 };
  72
  73 /* This is the struct describing how to write this record.  */
  74 static const struct iovec iov_notfound =
  75 {
  76   iov_base: (void *) &notfound,
  77   iov_len: sizeof (notfound)
  78 };
  79
  80
  81 struct hostdata
  82 {
  83   hst_response_header resp;
  84   char strdata[0];
  85 };
  86
  87
  88 static void
  89 cache_addhst (struct database *db, int fd, request_header *req, void *key,
  90               struct hostent *hst, uid_t owner)
  91 {
  92   ssize_t total;
  93   ssize_t written;
  94   time_t t = time (NULL);
  95
  96   if (hst == NULL)
  97     {
  98       /* We have no data.  This means we send the standard reply for this
  99          case.  */
 100       void *copy;
 101
 102       total = sizeof (notfound);
 103
 104       written = writev (fd, &iov_notfound, 1);
 105
 106       copy = malloc (req->key_len);
 107       if (copy == NULL)
 108         error (EXIT_FAILURE, errno, _("while allocating key copy"));
 109       memcpy (copy, key, req->key_len);
 110
 111       /* Compute the timeout time.  */
 112       t += db->negtimeout;
 113
 114       /* Now get the lock to safely insert the records.  */
 115       pthread_rwlock_rdlock (&db->lock);
 116
 117       cache_add (req->type, copy, req->key_len, &notfound,
 118                  sizeof (notfound), (void *) -1, 0, t, db, owner);
 119
 120       pthread_rwlock_unlock (&db->lock);
 121     }
 122   else
 123     {
 124       /* Determine the I/O structure.  */
 125       struct hostdata *data;
 126       size_t h_name_len = strlen (hst->h_name) + 1;
 127       size_t h_aliases_cnt;
 128       size_t *h_aliases_len;
 129       size_t h_addr_list_cnt;
 130       int addr_list_type;
 131       char *addresses;
 132       char *aliases;
 133       char *key_copy = NULL;
 134       char *cp;
 135       size_t cnt;
 136
 137       /* Determine the number of aliases.  */
 138       h_aliases_cnt = 0;
 139       for (cnt = 0; hst->h_aliases[cnt] != NULL; ++cnt)
 140         ++h_aliases_cnt;
 141       /* Determine the length of all aliases.  */
 142       h_aliases_len = alloca (h_aliases_cnt * sizeof (size_t));
 143       total = 0;
 144       for (cnt = 0; cnt < h_aliases_cnt; ++cnt)
 145         {
 146           h_aliases_len[cnt] = strlen (hst->h_aliases[cnt]) + 1;
 147           total += h_aliases_len[cnt];
 148         }
 149
 150       /* Determine the number of addresses.  */
 151       h_addr_list_cnt = 0;
 152       for (cnt = 0; hst->h_addr_list[cnt]; ++cnt)
 153         ++h_addr_list_cnt;
 154
 155       /* We allocate all data in one memory block: the iov vector,
 156          the response header and the dataset itself.  */
 157       total += (sizeof (struct hostdata)
 158                 + h_name_len
 159                 + h_aliases_cnt * sizeof (size_t)
 160                 + h_addr_list_cnt * hst->h_length);
 161
 162       data = (struct hostdata *) malloc (total + req->key_len);
 163       if (data == NULL)
 164         /* There is no reason to go on.  */
 165         error (EXIT_FAILURE, errno, _("while allocating cache entry"));
 166
 167       data->resp.found = 1;
 168       data->resp.h_name_len = h_name_len;
 169       data->resp.h_aliases_cnt = h_aliases_cnt;
 170       data->resp.h_addrtype = hst->h_addrtype;
 171       data->resp.h_length = hst->h_length;
 172       data->resp.h_addr_list_cnt = h_addr_list_cnt;
 173       data->resp.error = NETDB_SUCCESS;
 174
 175       cp = data->strdata;
 176
 177       cp = mempcpy (cp, hst->h_name, h_name_len);
 178       cp = mempcpy (cp, h_aliases_len, h_aliases_cnt * sizeof (size_t));
 179
 180       /* The normal addresses first.  */
 181       addresses = cp;
 182       for (cnt = 0; cnt < h_addr_list_cnt; ++cnt)
 183         cp = mempcpy (cp, hst->h_addr_list[cnt], hst->h_length);
 184
 185       /* Then the aliases.  */
 186       aliases = cp;
 187       for (cnt = 0; cnt < h_aliases_cnt; ++cnt)
 188         cp = mempcpy (cp, hst->h_aliases[cnt], h_aliases_len[cnt]);
 189
 190       assert (cp == data->strdata + total - sizeof (hst_response_header));
 191
 192       /* If we are adding a GETHOSTBYNAME{,v6} entry we must be prepared
 193          that the answer we get from the NSS does not contain the key
 194          itself.  This is the case if the resolver is used and the name
 195          is extended by the domainnames from /etc/resolv.conf.  Therefore
 196          we explicitly add the name here.  */
 197       if (req->type == GETHOSTBYNAME || req->type == GETHOSTBYNAMEv6)
 198         key_copy = memcpy (cp, key, req->key_len);
 199
 200       /* We write the dataset before inserting it to the database
 201          since while inserting this thread might block and so would
 202          unnecessarily let the receiver wait.  */
 203       written = write (fd, data, total);
 204
 205       addr_list_type = (hst->h_length == NS_INADDRSZ
 206                         ? GETHOSTBYADDR : GETHOSTBYADDRv6);
 207
 208       /* Compute the timeout time.  */
 209       t += db->postimeout;
 210
 211       /* Now get the lock to safely insert the records.  */
 212       pthread_rwlock_rdlock (&db->lock);
 213
 214       /* First add all the aliases.  If the record contains more than
 215          one IP address (used for load balancing etc) don't cache the
 216          entry.  This is something the current cache handling cannot
 217          handle and it is more than questionable whether it is
 218          worthwhile complicating the cache handling just for handling
 219          such a special case.  */
 220       if (hst->h_addr_list[1] == NULL)
 221         for (cnt = 0; cnt < h_aliases_cnt; ++cnt)
 222           {
 223             if (addr_list_type == GETHOSTBYADDR)
 224               cache_add (GETHOSTBYNAME, aliases, h_aliases_len[cnt], data,
 225                          total, data, 0, t, db, owner);
 226
 227             cache_add (GETHOSTBYNAMEv6, aliases, h_aliases_len[cnt], data,
 228                        total, data, 0, t, db, owner);
 229
 230             aliases += h_aliases_len[cnt];
 231           }
 232
 233       /* Next the normal addresses.  */
 234       for (cnt = 0; cnt < h_addr_list_cnt; ++cnt)
 235         {
 236           cache_add (addr_list_type, addresses, hst->h_length, data, total,
 237                      data, 0, t, db, owner);
 238           addresses += hst->h_length;
 239         }
 240
 241       /* If necessary the IPv6 addresses.  */
 242       if (addr_list_type == GETHOSTBYADDR)
 243         for (cnt = 0; cnt < h_addr_list_cnt; ++cnt)
 244           {
 245             cache_add (GETHOSTBYADDRv6, addresses, IN6ADDRSZ, data, total,
 246                        data, 0, t, db, owner);
 247             addresses += IN6ADDRSZ;
 248           }
 249
 250       /* Avoid adding names if more than one address is available.  See
 251          above for more info.  */
 252       if (hst->h_addr_list[1] == NULL)
 253         {
 254           /* If necessary add the key for this request.  */
 255           if (req->type == GETHOSTBYNAME || req->type == GETHOSTBYNAMEv6)
 256             {
 257               if (addr_list_type == GETHOSTBYADDR)
 258                 cache_add (GETHOSTBYNAME, key_copy, req->key_len, data, total,
 259                            data, 0, t, db, owner);
 260               cache_add (GETHOSTBYNAMEv6, key_copy, req->key_len, data,
 261                          total, data, 0, t, db, owner);
 262             }
 263
 264           /* And finally the name.  We mark this as the last entry.  */
 265           if (addr_list_type == GETHOSTBYADDR)
 266             cache_add (GETHOSTBYNAME, data->strdata, h_name_len, data, total,
 267                        data, 0, t, db, owner);
 268           cache_add (GETHOSTBYNAMEv6, data->strdata, h_name_len, data,
 269                      total, data, 1, t, db, owner);
 270         }
 271
 272       pthread_rwlock_unlock (&db->lock);
 273     }
 274
 275   if (written != total)
 276     {
 277       char buf[256];
 278       dbg_log (_("short write in %s: %s"),  __FUNCTION__,
 279                strerror_r (errno, buf, sizeof (buf)));
 280     }
 281 }
 282
 283
 284 void
 285 addhstbyname (struct database *db, int fd, request_header *req,
 286               void *key, uid_t uid)
 287 {
 288   /* Search for the entry matching the key.  Please note that we don't
 289      look again in the table whether the dataset is now available.  We
 290      simply insert it.  It does not matter if it is in there twice.  The
 291      pruning function only will look at the timestamp.  */
 292   int buflen = 512;
 293   char *buffer = alloca (buflen);
 294   struct hostent resultbuf;
 295   struct hostent *hst;
 296   uid_t oldeuid = 0;
 297
 298   if (debug_level > 0)
 299     dbg_log (_("Haven't found \"%s\" in hosts cache!"), key);
 300
 301   if (secure[hstdb])
 302     {
 303       oldeuid = geteuid ();
 304       seteuid (uid);
 305     }
 306
 307   while (__gethostbyname2_r (key, AF_INET, &resultbuf, buffer, buflen,
 308                              &hst, &h_errno) != 0
 309          && h_errno == NETDB_INTERNAL
 310          && errno == ERANGE)
 311     {
 312       errno = 0;
 313       buflen += 256;
 314       buffer = alloca (buflen);
 315     }
 316
 317   if (secure[hstdb])
 318     seteuid (oldeuid);
 319
 320   cache_addhst (db, fd, req, key, hst, uid);
 321 }
 322
 323
 324 void
 325 addhstbyaddr (struct database *db, int fd, request_header *req,
 326               void *key, uid_t uid)
 327 {
 328   /* Search for the entry matching the key.  Please note that we don't
 329      look again in the table whether the dataset is now available.  We
 330      simply insert it.  It does not matter if it is in there twice.  The
 331      pruning function only will look at the timestamp.  */
 332   int buflen = 512;
 333   char *buffer = alloca (buflen);
 334   struct hostent resultbuf;
 335   struct hostent *hst;
 336   uid_t oldeuid = 0;
 337
 338   if (debug_level > 0)
 339     {
 340       char buf[INET_ADDRSTRLEN];
 341       dbg_log (_("Haven't found \"%s\" in hosts cache!"),
 342                inet_ntop (AF_INET, key, buf, sizeof (buf)));
 343     }
 344
 345   if (secure[hstdb])
 346     {
 347       oldeuid = geteuid ();
 348       seteuid (uid);
 349     }
 350
 351   while (__gethostbyaddr_r (key, NS_INADDRSZ, AF_INET, &resultbuf, buffer,
 352                             buflen, &hst, &h_errno) != 0
 353          && h_errno == NETDB_INTERNAL
 354          && errno == ERANGE)
 355     {
 356       errno = 0;
 357       buflen += 256;
 358       buffer = alloca (buflen);
 359     }
 360
 361   if (secure[hstdb])
 362     seteuid (oldeuid);
 363
 364   cache_addhst (db, fd, req, key, hst, uid);
 365 }
 366
 367
 368 void
 369 addhstbynamev6 (struct database *db, int fd, request_header *req,
 370                 void *key, uid_t uid)
 371 {
 372   /* Search for the entry matching the key.  Please note that we don't
 373      look again in the table whether the dataset is now available.  We
 374      simply insert it.  It does not matter if it is in there twice.  The
 375      pruning function only will look at the timestamp.  */
 376   int buflen = 512;
 377   char *buffer = alloca (buflen);
 378   struct hostent resultbuf;
 379   struct hostent *hst;
 380   uid_t oldeuid = 0;
 381
 382   if (debug_level > 0)
 383     {
 384       char buf[INET6_ADDRSTRLEN];
 385
 386       dbg_log (_("Haven't found \"%s\" in hosts cache!"),
 387                inet_ntop (AF_INET6, key, buf, sizeof (buf)));
 388     }
 389
 390   if (secure[hstdb])
 391     {
 392       oldeuid = geteuid ();
 393       seteuid (uid);
 394     }
 395
 396   while (__gethostbyname2_r (key, AF_INET6, &resultbuf, buffer, buflen,
 397                              &hst, &h_errno) != 0
 398          && h_errno == NETDB_INTERNAL
 399          && errno == ERANGE)
 400     {
 401       errno = 0;
 402       buflen += 256;
 403       buffer = alloca (buflen);
 404     }
 405
 406   if (secure[hstdb])
 407     seteuid (oldeuid);
 408
 409   cache_addhst (db, fd, req, key, hst, uid);
 410 }
 411
 412
 413 void
 414 addhstbyaddrv6 (struct database *db, int fd, request_header *req,
 415                 void *key, uid_t uid)
 416 {
 417   /* Search for the entry matching the key.  Please note that we don't
 418      look again in the table whether the dataset is now available.  We
 419      simply insert it.  It does not matter if it is in there twice.  The
 420      pruning function only will look at the timestamp.  */
 421   int buflen = 512;
 422   char *buffer = alloca (buflen);
 423   struct hostent resultbuf;
 424   struct hostent *hst;
 425   uid_t oldeuid = 0;
 426
 427   if (debug_level > 0)
 428     {
 429       char buf[INET6_ADDRSTRLEN];
 430       dbg_log (_("Haven't found \"%s\" in hosts cache!"),
 431                inet_ntop (AF_INET6, key, buf, sizeof (buf)));
 432     }
 433
 434   if (secure[hstdb])
 435     {
 436       oldeuid = geteuid ();
 437       seteuid (uid);
 438     }
 439
 440   while (__gethostbyaddr_r (key, NS_IN6ADDRSZ, AF_INET6, &resultbuf,
 441                             buffer, buflen, &hst, &h_errno) != 0
 442          && h_errno == NETDB_INTERNAL
 443          && errno == ERANGE)
 444     {
 445       errno = 0;
 446       buflen += 256;
 447       buffer = alloca (buflen);
 448     }
 449
 450   if (secure[hstdb])
 451     seteuid (oldeuid);
 452
 453   cache_addhst (db, fd, req, key, hst, uid);
 454 }