nscd/hstcache.c

   1 /* Cache handling for host lookup.
   2    Copyright (C) 1998 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 <arpa/inet.h>
  32
  33 #include "nscd.h"
  34 #include "dbg_log.h"
  35
  36 /* Get implementation for some internal functions.  */
  37 #include "../resolv/mapv4v6addr.h"
  38
  39
  40 /* This is the standard reply in case the service is disabled.  */
  41 static const hst_response_header disabled =
  42 {
  43   version: NSCD_VERSION,
  44   found: -1,
  45   h_name_len: 0,
  46   h_aliases_cnt: 0,
  47   h_addrtype: -1,
  48   h_length: -1,
  49   h_addr_list_cnt: 0,
  50   error: NETDB_INTERNAL
  51 };
  52
  53 /* This is the struct describing how to write this record.  */
  54 const struct iovec hst_iov_disabled =
  55 {
  56   iov_base: (void *) &disabled,
  57   iov_len: sizeof (disabled)
  58 };
  59
  60
  61 /* This is the standard reply in case we haven't found the dataset.  */
  62 static const hst_response_header notfound =
  63 {
  64   version: NSCD_VERSION,
  65   found: 0,
  66   h_name_len: 0,
  67   h_aliases_cnt: 0,
  68   h_addrtype: -1,
  69   h_length: -1,
  70   h_addr_list_cnt: 0,
  71   error: HOST_NOT_FOUND
  72 };
  73
  74 /* This is the struct describing how to write this record.  */
  75 static const struct iovec iov_notfound =
  76 {
  77   iov_base: (void *) &notfound,
  78   iov_len: sizeof (notfound)
  79 };
  80
  81
  82 struct hostdata
  83 {
  84   hst_response_header resp;
  85   char strdata[0];
  86 };
  87
  88
  89 static void
  90 cache_addhst (struct database *db, int fd, request_header *req, void *key,
  91               struct hostent *hst)
  92 {
  93   ssize_t total;
  94   ssize_t written;
  95   time_t t = time (NULL);
  96
  97   if (hst == NULL)
  98     {
  99       /* We have no data.  This means we send the standard reply for this
 100          case.  */
 101       void *copy;
 102
 103       total = sizeof (notfound);
 104
 105       written = writev (fd, &iov_notfound, 1);
 106
 107       copy = malloc (req->key_len);
 108       if (copy == NULL)
 109         error (EXIT_FAILURE, errno, _("while allocating key copy"));
 110       memcpy (copy, key, req->key_len);
 111
 112       /* Compute the timeout time.  */
 113       t += db->negtimeout;
 114
 115       /* Now get the lock to safely insert the records.  */
 116       pthread_rwlock_rdlock (&db->lock);
 117
 118       cache_add (req->type, copy, req->key_len, &iov_notfound,
 119                  sizeof (notfound), (void *) -1, 0, t, db);
 120
 121       pthread_rwlock_unlock (&db->lock);
 122     }
 123   else
 124     {
 125       /* Determine the I/O structure.  */
 126       struct hostdata *data;
 127       size_t h_name_len = strlen (hst->h_name) + 1;
 128       size_t h_aliases_cnt;
 129       size_t *h_aliases_len;
 130       size_t h_addr_list_cnt;
 131       int addr_list_type;
 132       char *addresses;
 133       char *aliases;
 134       char *key_copy = NULL;
 135       char *cp;
 136       size_t cnt;
 137
 138       /* Determine the number of aliases.  */
 139       h_aliases_cnt = 0;
 140       for (cnt = 0; hst->h_aliases[cnt] != NULL; ++cnt)
 141         ++h_aliases_cnt;
 142       /* Determine the length of all aliases.  */
 143       h_aliases_len = alloca (h_aliases_cnt * sizeof (size_t));
 144       total = 0;
 145       for (cnt = 0; cnt < h_aliases_cnt; ++cnt)
 146         {
 147           h_aliases_len[cnt] = strlen (hst->h_aliases[cnt]) + 1;
 148           total += h_aliases_len[cnt];
 149         }
 150
 151       /* Determine the number of addresses.  */
 152       h_addr_list_cnt = 0;
 153       for (cnt = 0; hst->h_addr_list[cnt]; ++cnt)
 154         ++h_addr_list_cnt;
 155
 156       /* We allocate all data in one memory block: the iov vector,
 157          the response header and the dataset itself.  */
 158       total += (sizeof (struct hostdata)
 159                 + h_name_len
 160                 + h_aliases_cnt * sizeof (size_t)
 161                 + h_addr_list_cnt * (hst->h_length
 162                                      + (hst->h_length == INADDRSZ
 163                                         ? IN6ADDRSZ : 0)));
 164
 165       data = (struct hostdata *) malloc (total + req->key_len);
 166       if (data == NULL)
 167         /* There is no reason to go on.  */
 168         error (EXIT_FAILURE, errno, _("while allocating cache entry"));
 169
 170       data->resp.found = 1;
 171       data->resp.h_name_len = h_name_len;
 172       data->resp.h_aliases_cnt = h_aliases_cnt;
 173       data->resp.h_addrtype = hst->h_addrtype;
 174       data->resp.h_length = hst->h_length;
 175       data->resp.h_addr_list_cnt = h_addr_list_cnt;
 176       data->resp.error = NETDB_SUCCESS;
 177
 178       cp = data->strdata;
 179
 180       cp = mempcpy (cp, hst->h_name, h_name_len);
 181       cp = mempcpy (cp, h_aliases_len, h_aliases_cnt * sizeof (size_t));
 182
 183       /* The normal addresses first.  */
 184       addresses = cp;
 185       for (cnt = 0; cnt < h_addr_list_cnt; ++cnt)
 186         cp = mempcpy (cp, hst->h_addr_list[cnt], hst->h_length);
 187
 188       /* And the generated IPv6 addresses if necessary.  */
 189       if (hst->h_length == INADDRSZ)
 190         {
 191           /* Generate the IPv6 addresses.  */
 192           for (cnt = 0; cnt < h_addr_list_cnt; cp += IN6ADDRSZ, ++cnt)
 193             map_v4v6_address (hst->h_addr_list[cnt], cp);
 194         }
 195
 196       /* Then the aliases.  */
 197       aliases = cp;
 198       for (cnt = 0; cnt < h_aliases_cnt; ++cnt)
 199         cp = mempcpy (cp, hst->h_aliases[cnt], h_aliases_len[cnt]);
 200
 201       assert (cp == data->strdata + total - sizeof (hst_response_header));
 202
 203       /* If we are adding a GETHOSTBYNAME{,v6} entry we must be prepared
 204          that the answer we get from the NSS does not contain the key
 205          itself.  This is the case if the resolver is used and the name
 206          is extended by the domainnames from /etc/resolv.conf.  Therefore
 207          we explicitly add the name here.  */
 208       if (req->type == GETHOSTBYNAME || req->type == GETHOSTBYNAMEv6)
 209         key_copy = memcpy (cp, key, req->key_len);
 210
 211       /* We write the dataset before inserting it to the database
 212          since while inserting this thread might block and so would
 213          unnecessarily let the receiver wait.  */
 214       written = write (fd, data, total);
 215
 216       addr_list_type = (hst->h_length == INADDRSZ
 217                         ? GETHOSTBYADDR : GETHOSTBYADDRv6);
 218
 219       /* Compute the timeout time.  */
 220       t += db->postimeout;
 221
 222       /* Now get the lock to safely insert the records.  */
 223       pthread_rwlock_rdlock (&db->lock);
 224
 225       /* First add all the aliases.  */
 226       for (cnt = 0; cnt < h_aliases_cnt; ++cnt)
 227         {
 228           if (addr_list_type == GETHOSTBYADDR)
 229             cache_add (GETHOSTBYNAME, aliases, h_aliases_len[cnt], data, total,
 230                        data, 0, t, db);
 231
 232           cache_add (GETHOSTBYNAMEv6, aliases, h_aliases_len[cnt], data, total,
 233                      data, 0, t, db);
 234
 235           aliases += h_aliases_len[cnt];
 236         }
 237
 238       /* Next the normal addresses.  */
 239       for (cnt = 0; cnt < h_addr_list_cnt; ++cnt)
 240         {
 241           cache_add (addr_list_type, addresses, hst->h_length, data, total,
 242                      data, 0, t, db);
 243           addresses += hst->h_length;
 244         }
 245
 246       /* If necessary the IPv6 addresses.  */
 247       if (addr_list_type == GETHOSTBYADDR)
 248         for (cnt = 0; cnt < h_addr_list_cnt; ++cnt)
 249           {
 250             cache_add (GETHOSTBYADDRv6, addresses, IN6ADDRSZ, data, total,
 251                        data, 0, t, db);
 252             addresses += IN6ADDRSZ;
 253           }
 254
 255       /* If necessary add the key for this request.  */
 256       if (req->type == GETHOSTBYNAME || req->type == GETHOSTBYNAMEv6)
 257         {
 258           if (addr_list_type == GETHOSTBYADDR)
 259             cache_add (GETHOSTBYNAME, key_copy, req->key_len, data, total,
 260                        data, 0, t, db);
 261           cache_add (GETHOSTBYNAMEv6, key_copy, req->key_len, data,
 262                      total, data, 0, t, db);
 263         }
 264
 265       /* And finally the name.  We mark this as the last entry.  */
 266       if (addr_list_type == GETHOSTBYADDR)
 267         cache_add (GETHOSTBYNAME, data->strdata, h_name_len, data, total, data,
 268                    0, t, db);
 269       cache_add (GETHOSTBYNAMEv6, data->strdata, h_name_len, data,
 270                  total, data, 1, t, db);
 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, void *key)
 286 {
 287   /* Search for the entry matching the key.  Please note that we don't
 288      look again in the table whether the dataset is now available.  We
 289      simply insert it.  It does not matter if it is in there twice.  The
 290      pruning function only will look at the timestamp.  */
 291   int buflen = 512;
 292   char *buffer = alloca (buflen);
 293   struct hostent resultbuf;
 294   struct hostent *hst;
 295
 296   if (debug_level > 0)
 297     dbg_log (_("Haven't found \"%s\" in hosts cache!"), key);
 298
 299   while (gethostbyname2_r (key, AF_INET, &resultbuf, buffer, buflen, &hst,
 300                            &h_errno) != 0
 301          && h_errno == NETDB_INTERNAL
 302          && errno == ERANGE)
 303     {
 304       errno = 0;
 305       buflen += 256;
 306       buffer = alloca (buflen);
 307     }
 308
 309   cache_addhst (db, fd, req, key, hst);
 310 }
 311
 312
 313 void
 314 addhstbyaddr (struct database *db, int fd, request_header *req, void *key)
 315 {
 316   /* Search for the entry matching the key.  Please note that we don't
 317      look again in the table whether the dataset is now available.  We
 318      simply insert it.  It does not matter if it is in there twice.  The
 319      pruning function only will look at the timestamp.  */
 320   int buflen = 512;
 321   char *buffer = alloca (buflen);
 322   struct hostent resultbuf;
 323   struct hostent *hst;
 324
 325   if (debug_level > 0)
 326     {
 327       char buf[64];
 328       dbg_log (_("Haven't found \"%s\" in hosts cache!"),
 329                inet_ntop (AF_INET, key, buf, sizeof (buf)));
 330     }
 331
 332   while (gethostbyaddr_r (key, INADDRSZ, AF_INET, &resultbuf, buffer, buflen,
 333                           &hst, &h_errno) != 0
 334          && h_errno == NETDB_INTERNAL
 335          && errno == ERANGE)
 336     {
 337       errno = 0;
 338       buflen += 256;
 339       buffer = alloca (buflen);
 340     }
 341
 342   cache_addhst (db, fd, req, key, hst);
 343 }
 344
 345
 346 void
 347 addhstbynamev6 (struct database *db, int fd, request_header *req, void *key)
 348 {
 349   /* Search for the entry matching the key.  Please note that we don't
 350      look again in the table whether the dataset is now available.  We
 351      simply insert it.  It does not matter if it is in there twice.  The
 352      pruning function only will look at the timestamp.  */
 353   int buflen = 512;
 354   char *buffer = alloca (buflen);
 355   struct hostent resultbuf;
 356   struct hostent *hst;
 357
 358   if (debug_level > 0)
 359     dbg_log (_("Haven't found \"%s\" in hosts cache!"), key);
 360
 361   while (gethostbyname2_r (key, AF_INET6, &resultbuf, buffer, buflen, &hst,
 362                            &h_errno) != 0
 363          && h_errno == NETDB_INTERNAL
 364          && errno == ERANGE)
 365     {
 366       errno = 0;
 367       buflen += 256;
 368       buffer = alloca (buflen);
 369     }
 370
 371   cache_addhst (db, fd, req, key, hst);
 372 }
 373
 374
 375 void
 376 addhstbyaddrv6 (struct database *db, int fd, request_header *req, void *key)
 377 {
 378   /* Search for the entry matching the key.  Please note that we don't
 379      look again in the table whether the dataset is now available.  We
 380      simply insert it.  It does not matter if it is in there twice.  The
 381      pruning function only will look at the timestamp.  */
 382   int buflen = 512;
 383   char *buffer = alloca (buflen);
 384   struct hostent resultbuf;
 385   struct hostent *hst;
 386
 387   if (debug_level > 0)
 388     {
 389       char buf[64];
 390       dbg_log (_("Haven't found \"%s\" in hosts cache!"),
 391                inet_ntop (AF_INET6, key, buf, sizeof (buf)));
 392     }
 393
 394   while (gethostbyaddr_r (key, IN6ADDRSZ, AF_INET6, &resultbuf, buffer, buflen,
 395                           &hst, &h_errno) != 0
 396          && h_errno == NETDB_INTERNAL
 397          && errno == ERANGE)
 398     {
 399       errno = 0;
 400       buflen += 256;
 401       buffer = alloca (buflen);
 402     }
 403
 404   cache_addhst (db, fd, req, key, hst);
 405 }