nscd/connections.c

   1 /* Inner loops of cache daemon.
   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 <error.h>
  23 #include <errno.h>
  24 #include <pthread.h>
  25 #include <stdlib.h>
  26 #include <unistd.h>
  27 #include <sys/param.h>
  28 #include <sys/poll.h>
  29 #include <sys/socket.h>
  30 #include <sys/stat.h>
  31 #include <sys/un.h>
  32
  33 #include "nscd.h"
  34 #include "dbg_log.h"
  35
  36
  37 /* Mapping of request type to database.  */
  38 static const dbtype serv2db[LASTDBREQ + 1] =
  39 {
  40   [GETPWBYNAME] = pwddb,
  41   [GETPWBYUID] = pwddb,
  42   [GETGRBYNAME] = grpdb,
  43   [GETGRBYGID] = grpdb,
  44   [GETHOSTBYNAME] = hstdb,
  45   [GETHOSTBYNAMEv6] = hstdb,
  46   [GETHOSTBYADDR] = hstdb,
  47   [GETHOSTBYADDRv6] = hstdb,
  48 };
  49
  50 /* Map request type to a string.  */
  51 const char *serv2str[LASTREQ] =
  52 {
  53   [GETPWBYNAME] = "GETPWBYNAME",
  54   [GETPWBYUID] = "GETPWBYUID",
  55   [GETGRBYNAME] = "GETGRBYNAME",
  56   [GETGRBYGID] = "GETGRBYGID",
  57   [GETHOSTBYNAME] = "GETHOSTBYNAME",
  58   [GETHOSTBYNAMEv6] = "GETHOSTBYNAMEv6",
  59   [GETHOSTBYADDR] = "GETHOSTBYADDR",
  60   [GETHOSTBYADDRv6] = "GETHOSTBYADDRv6",
  61   [SHUTDOWN] = "SHUTDOWN",
  62   [GETSTAT] = "GETSTAT"
  63 };
  64
  65 /* The control data structures for the services.  */
  66 static struct database dbs[lastdb] =
  67 {
  68   [pwddb] = {
  69     lock: PTHREAD_RWLOCK_INITIALIZER,
  70     enabled: 1,
  71     check_file: 1,
  72     filename: "/etc/passwd",
  73     module: 211,
  74     disabled_iov: &pwd_iov_disabled
  75   },
  76   [grpdb] = {
  77     lock: PTHREAD_RWLOCK_INITIALIZER,
  78     enabled: 1,
  79     check_file: 1,
  80     filename: "/etc/group",
  81     module: 211,
  82     disabled_iov: &grp_iov_disabled
  83   },
  84   [hstdb] = {
  85     lock: PTHREAD_RWLOCK_INITIALIZER,
  86     enabled: 1,
  87     check_file: 1,
  88     filename: "/etc/hosts",
  89     module: 211,
  90     disabled_iov: &hst_iov_disabled
  91   }
  92 };
  93
  94 /* Number of threads to use.  */
  95 int nthreads = -1;
  96
  97 /* Socket for incoming connections.  */
  98 static int sock;
  99
 100
 101 /* Initialize database information structures.  */
 102 void
 103 nscd_init (const char *conffile)
 104 {
 105   struct sockaddr_un sock_addr;
 106   size_t cnt;
 107
 108   /* Read the configuration file.  */
 109   if (nscd_parse_file (conffile, dbs) != 0)
 110     {
 111       /* We couldn't read the configuration file.  Disable all services
 112          by shutting down the srever.  */
 113       dbg_log (_("cannot read configuration file; this is fatal"));
 114       exit (1);
 115     }
 116   if (nthreads == -1)
 117     /* No configuration for this value, assume a default.  */
 118     nthreads = 2 * lastdb;
 119
 120   for (cnt = 0; cnt < lastdb; ++cnt)
 121     if (dbs[cnt].enabled)
 122       {
 123         pthread_rwlock_init (&dbs[cnt].lock, NULL);
 124
 125         dbs[cnt].array = (struct hashentry **)
 126           calloc (dbs[cnt].module, sizeof (struct hashentry *));
 127         if (dbs[cnt].array == NULL)
 128           error (EXIT_FAILURE, errno, "while allocating cache");
 129
 130         if (dbs[cnt].check_file)
 131           {
 132             /* We need the modification date of the file.  */
 133             struct stat st;
 134
 135             if (stat (dbs[cnt].filename, &st) < 0)
 136               {
 137                 char buf[128];
 138                 /* We cannot stat() the file, disable file checking.  */
 139                 dbg_log (_("cannot stat() file `%s': %s"),
 140                          dbs[cnt].filename,
 141                          strerror_r (errno, buf, sizeof (buf)));
 142                 dbs[cnt].check_file = 0;
 143               }
 144             else
 145               dbs[cnt].file_mtime = st.st_mtime;
 146           }
 147       }
 148
 149   /* Create the socket.  */
 150   sock = socket (AF_UNIX, SOCK_STREAM, 0);
 151   if (sock < 0)
 152     {
 153       dbg_log (_("cannot open socket: %s"), strerror (errno));
 154       exit (1);
 155     }
 156   /* Bind a name to the socket.  */
 157   sock_addr.sun_family = AF_UNIX;
 158   strcpy (sock_addr.sun_path, _PATH_NSCDSOCKET);
 159   if (bind (sock, (struct sockaddr *) &sock_addr, sizeof (sock_addr)) < 0)
 160     {
 161       dbg_log ("%s: %s", _PATH_NSCDSOCKET, strerror (errno));
 162       exit (1);
 163     }
 164
 165   /* Set permissions for the socket.  */
 166   chmod (_PATH_NSCDSOCKET, 0666);
 167
 168   /* Set the socket up to accept connections.  */
 169   if (listen (sock, SOMAXCONN) < 0)
 170     {
 171       dbg_log (_("cannot enable socket to accept connections: %s"),
 172                strerror (errno));
 173       exit (1);
 174     }
 175 }
 176
 177
 178 /* Close the connections.  */
 179 void
 180 close_sockets (void)
 181 {
 182   close (sock);
 183 }
 184
 185
 186 /* Handle new request.  */
 187 static void
 188 handle_request (int fd, request_header *req, void *key)
 189 {
 190   if (debug_level > 0)
 191     dbg_log (_("handle_requests: request received (Version = %d)"),
 192              req->version);
 193
 194   if (req->version != NSCD_VERSION)
 195     {
 196       dbg_log (_("\
 197 cannot handle old request version %d; current version is %d"),
 198                req->version, NSCD_VERSION);
 199       return;
 200     }
 201
 202   if (req->type >= GETPWBYNAME && req->type <= LASTDBREQ)
 203     {
 204       struct hashentry *cached;
 205       struct database *db = &dbs[serv2db[req->type]];
 206
 207       if (debug_level > 0)
 208         dbg_log ("\t%s (%s)", serv2str[req->type], key);
 209
 210       /* Is this service enabled?  */
 211       if (!db->enabled)
 212         {
 213           /* No sent the prepared record.  */
 214           if (TEMP_FAILURE_RETRY (write (fd, db->disabled_iov->iov_base,
 215                                          db->disabled_iov->iov_len))
 216               != db->disabled_iov->iov_len)
 217             {
 218               /* We have problems sending the result.  */
 219               char buf[256];
 220               dbg_log (_("cannot write result: %s"),
 221                        strerror_r (errno, buf, sizeof (buf)));
 222             }
 223
 224           return;
 225         }
 226
 227       /* Be sure we can read the data.  */
 228       pthread_rwlock_rdlock (&db->lock);
 229
 230       /* See whether we can handle it from the cache.  */
 231       cached = (struct hashentry *) cache_search (req->type, key, req->key_len,
 232                                                   db);
 233       if (cached != NULL)
 234         {
 235           /* Hurray it's in the cache.  */
 236           if (TEMP_FAILURE_RETRY (write (fd, cached->packet, cached->total))
 237               != cached->total)
 238             {
 239               /* We have problems sending the result.  */
 240               char buf[256];
 241               dbg_log (_("cannot write result: %s"),
 242                        strerror_r (errno, buf, sizeof (buf)));
 243             }
 244
 245           pthread_rwlock_unlock (&db->lock);
 246
 247           return;
 248         }
 249
 250       pthread_rwlock_unlock (&db->lock);
 251     }
 252   else
 253     if (debug_level > 0)
 254       dbg_log ("\t%s", serv2str[req->type]);
 255
 256   /* Handle the request.  */
 257   switch (req->type)
 258     {
 259     case GETPWBYNAME:
 260       addpwbyname (&dbs[serv2db[req->type]], fd, req, key);
 261       break;
 262
 263     case GETPWBYUID:
 264       addpwbyuid (&dbs[serv2db[req->type]], fd, req, key);
 265       break;
 266
 267     case GETGRBYNAME:
 268       addgrbyname (&dbs[serv2db[req->type]], fd, req, key);
 269       break;
 270
 271     case GETGRBYGID:
 272       addgrbygid (&dbs[serv2db[req->type]], fd, req, key);
 273       break;
 274
 275     case GETHOSTBYNAME:
 276       addhstbyname (&dbs[serv2db[req->type]], fd, req, key);
 277       break;
 278
 279     case GETHOSTBYNAMEv6:
 280       addhstbynamev6 (&dbs[serv2db[req->type]], fd, req, key);
 281       break;
 282
 283     case GETHOSTBYADDR:
 284       addhstbyaddr (&dbs[serv2db[req->type]], fd, req, key);
 285       break;
 286
 287     case GETHOSTBYADDRv6:
 288       addhstbyaddrv6 (&dbs[serv2db[req->type]], fd, req, key);
 289       break;
 290
 291     case GETSTAT:
 292       send_stats (fd, dbs);
 293       break;
 294
 295     case SHUTDOWN:
 296       termination_handler (0);
 297       break;
 298
 299     default:
 300       abort ();
 301     }
 302 }
 303
 304
 305 /* This is the main loop.  It is replicated in different threads but the
 306    `poll' call makes sure only one thread handles an incoming connection.  */
 307 static void *
 308 __attribute__ ((__noreturn__))
 309 nscd_run (void *p)
 310 {
 311   int my_number = (int) p;
 312   struct pollfd conn;
 313   int run_prune = my_number < lastdb && dbs[my_number].enabled;
 314   time_t now = time (NULL);
 315   time_t next_prune = now + 15;
 316   int timeout = run_prune ? 1000 * (next_prune - now) : -1;
 317
 318   conn.fd = sock;
 319   conn.events = POLLRDNORM;
 320
 321   while (1)
 322     {
 323       int nr = poll (&conn, 1, timeout);
 324
 325       if (nr == 0)
 326         {
 327           /* The `poll' call timed out.  It's time to clean up the cache.  */
 328           assert (my_number < lastdb);
 329           now = time (NULL);
 330           prune_cache (&dbs[my_number], now);
 331           next_prune = now + 15;
 332           timeout = 1000 * (next_prune - now);
 333           continue;
 334         }
 335
 336       /* We have a new incoming connection.  */
 337       if (conn.revents & (POLLRDNORM|POLLERR|POLLHUP|POLLNVAL))
 338         {
 339           /* Accept the connection.  */
 340           int fd = accept (conn.fd, NULL, NULL);
 341           request_header req;
 342           char buf[256];
 343
 344           if (fd < 0)
 345             {
 346               dbg_log (_("while accepting connection: %s"),
 347                        strerror_r (errno, buf, sizeof (buf)));
 348               continue;
 349             }
 350
 351           /* Now read the request.  */
 352           if (TEMP_FAILURE_RETRY (read (fd, &req, sizeof (req)))
 353               != sizeof (req))
 354             {
 355               dbg_log (_("short read while reading request: %s"),
 356                        strerror_r (errno, buf, sizeof (buf)));
 357               close (fd);
 358               continue;
 359             }
 360
 361           /* It should not be possible to crash the nscd with a silly
 362              request (i.e., a terribly large key.  We limit the size
 363              to 1kb.  */
 364           if (req.key_len < 0 || req.key_len > 1024)
 365             {
 366               dbg_log (_("key length in request to long: %Zd"), req.key_len);
 367               close (fd);
 368               continue;
 369             }
 370           else
 371             {
 372               /* Get the key.  */
 373               char keybuf[req.key_len];
 374
 375               if (TEMP_FAILURE_RETRY (read (fd, keybuf, req.key_len))
 376                   != req.key_len)
 377                 {
 378                   dbg_log (_("short read while reading request key: %s"),
 379                            strerror_r (errno, buf, sizeof (buf)));
 380                   close (fd);
 381                   continue;
 382                 }
 383
 384               /* Phew, we got all the data, now process it.  */
 385               handle_request (fd, &req, keybuf);
 386
 387               /* We are done.  */
 388               close (fd);
 389             }
 390         }
 391
 392       if (run_prune)
 393         {
 394           now = time (NULL);
 395           timeout = now < next_prune ? 1000 * (next_prune - now) : 0;
 396         }
 397     }
 398 }
 399
 400
 401 /* Start all the threads we want.  The initial process is thread no. 1.  */
 402 void
 403 start_threads (void)
 404 {
 405   int i;
 406   pthread_attr_t attr;
 407   pthread_t th;
 408
 409   pthread_attr_init (&attr);
 410   pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
 411
 412   /* We allow less than LASTDB threads only for debugging.  */
 413   if (debug_level == 0)
 414     nthreads = MAX (nthreads, lastdb);
 415
 416   for (i = 1; i < nthreads; ++i)
 417     pthread_create (&th, &attr, nscd_run, (void *) i);
 418
 419   pthread_attr_destroy (&attr);
 420
 421   nscd_run ((void *) 0);
 422 }