src/util/client.c

   1 /*
   2      This file is part of GNUnet.
   3      (C) 2001, 2002, 2006, 2008, 2009 Christian Grothoff (and other contributing authors)
   4
   5      GNUnet is free software; you can redistribute it and/or modify
   6      it under the terms of the GNU General Public License as published
   7      by the Free Software Foundation; either version 2, or (at your
   8      option) any later version.
   9
  10      GNUnet is distributed in the hope that it will be useful, but
  11      WITHOUT ANY WARRANTY; without even the implied warranty of
  12      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13      General Public License for more details.
  14
  15      You should have received a copy of the GNU General Public License
  16      along with GNUnet; see the file COPYING.  If not, write to the
  17      Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18      Boston, MA 02111-1307, USA.
  19 */
  20
  21 /**
  22  * @file util/client.c
  23  * @brief code for access to services
  24  * @author Christian Grothoff
  25  *
  26  * Generic TCP code for reliable, record-oriented TCP
  27  * connections between clients and service providers.
  28  */
  29
  30 #include "platform.h"
  31 #include "gnunet_common.h"
  32 #include "gnunet_client_lib.h"
  33 #include "gnunet_protocols.h"
  34 #include "gnunet_server_lib.h"
  35 #include "gnunet_scheduler_lib.h"
  36
  37 #define DEBUG_CLIENT GNUNET_NO
  38
  39 /**
  40  * Struct to refer to a GNUnet TCP connection.
  41  * This is more than just a socket because if the server
  42  * drops the connection, the client automatically tries
  43  * to reconnect (and for that needs connection information).
  44  */
  45 struct GNUNET_CLIENT_Connection
  46 {
  47
  48   /**
  49    * the socket handle, NULL if not live
  50    */
  51   struct GNUNET_NETWORK_SocketHandle *sock;
  52
  53   /**
  54    * Our scheduler.
  55    */
  56   struct GNUNET_SCHEDULER_Handle *sched;
  57
  58   /**
  59    * Name of the service we interact with.
  60    */
  61   char *service_name;
  62
  63   /**
  64    * ID of task used for receiving.
  65    */
  66   GNUNET_SCHEDULER_TaskIdentifier receiver_task;
  67
  68   /**
  69    * Handler for current receiver task.
  70    */
  71   GNUNET_CLIENT_MessageHandler receiver_handler;
  72
  73   /**
  74    * Closure for receiver_handler.
  75    */
  76   void *receiver_handler_cls;
  77
  78   /**
  79    * Handler for service test completion (NULL unless in service_test)
  80    */
  81   GNUNET_SCHEDULER_Task test_cb;
  82
  83   /**
  84    * Closure for test_cb (NULL unless in service_test)
  85    */
  86   void *test_cb_cls;
  87
  88   /**
  89    * Buffer for received message.
  90    */
  91   char *received_buf;
  92
  93   /**
  94    * Timeout for receiving a response (absolute time).
  95    */
  96   struct GNUNET_TIME_Absolute receive_timeout;
  97
  98   /**
  99    * Number of bytes in received_buf that are valid.
 100    */
 101   size_t received_pos;
 102
 103   /**
 104    * Size of received_buf.
 105    */
 106   size_t received_size;
 107
 108   /**
 109    * Do we have a complete response in received_buf?
 110    */
 111   int msg_complete;
 112
 113 };
 114
 115
 116 /**
 117  * Get a connection with a service.
 118  *
 119  * @param sched scheduler to use
 120  * @param service_name name of the service
 121  * @param cfg configuration to use
 122  * @return NULL on error (service unknown to configuration)
 123  */
 124 struct GNUNET_CLIENT_Connection *
 125 GNUNET_CLIENT_connect (struct GNUNET_SCHEDULER_Handle *sched,
 126                        const char *service_name,
 127                        struct GNUNET_CONFIGURATION_Handle *cfg)
 128 {
 129   struct GNUNET_CLIENT_Connection *ret;
 130   struct GNUNET_NETWORK_SocketHandle *sock;
 131   char *hostname;
 132   unsigned long long port;
 133
 134   if ((GNUNET_OK !=
 135        GNUNET_CONFIGURATION_get_value_number (cfg,
 136                                               service_name,
 137                                               "PORT",
 138                                               &port)) ||
 139       (port > 65535) ||
 140       (GNUNET_OK !=
 141        GNUNET_CONFIGURATION_get_value_string (cfg,
 142                                               service_name,
 143                                               "HOSTNAME", &hostname)))
 144     {
 145       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
 146                   "Could not determine valid hostname and port for service `%s' from configuration.\n",
 147                   service_name);
 148       return NULL;
 149     }
 150   sock = GNUNET_NETWORK_socket_create_from_connect (sched,
 151                                                     hostname,
 152                                                     port,
 153                                                     GNUNET_SERVER_MAX_MESSAGE_SIZE);
 154   GNUNET_free (hostname);
 155   if (sock == NULL)
 156     return NULL;
 157   ret = GNUNET_malloc (sizeof (struct GNUNET_CLIENT_Connection));
 158   ret->sock = sock;
 159   ret->sched = sched;
 160   ret->service_name = GNUNET_strdup (service_name);
 161   return ret;
 162 }
 163
 164
 165 /**
 166  * Receiver task has completed, free rest of client
 167  * data structures.
 168  */
 169 static void
 170 finish_cleanup (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
 171 {
 172   struct GNUNET_CLIENT_Connection *sock = cls;
 173
 174   GNUNET_array_grow (sock->received_buf, sock->received_size, 0);
 175   GNUNET_free (sock->service_name);
 176   GNUNET_free (sock);
 177 }
 178
 179
 180 /**
 181  * Destroy connection with the service.
 182  */
 183 void
 184 GNUNET_CLIENT_disconnect (struct GNUNET_CLIENT_Connection *sock)
 185 {
 186   GNUNET_assert (sock->sock != NULL);
 187   GNUNET_NETWORK_socket_destroy (sock->sock);
 188   sock->sock = NULL;
 189   sock->receiver_handler = NULL;
 190   GNUNET_SCHEDULER_add_after (sock->sched,
 191                               GNUNET_YES,
 192                               GNUNET_SCHEDULER_PRIORITY_KEEP,
 193                               sock->receiver_task, &finish_cleanup, sock);
 194 }
 195
 196
 197 /**
 198  * check if message is complete
 199  */
 200 static void
 201 check_complete (struct GNUNET_CLIENT_Connection *conn)
 202 {
 203   if ((conn->received_pos >= sizeof (struct GNUNET_MessageHeader)) &&
 204       (conn->received_pos >=
 205        ntohs (((const struct GNUNET_MessageHeader *) conn->received_buf)->
 206               size)))
 207     conn->msg_complete = GNUNET_YES;
 208 }
 209
 210
 211 /**
 212  * Callback function for data received from the network.  Note that
 213  * both "available" and "err" would be 0 if the read simply timed out.
 214  *
 215  * @param cls closure
 216  * @param buf pointer to received data
 217  * @param available number of bytes availabe in "buf",
 218  *        possibly 0 (on errors)
 219  * @param addr address of the sender
 220  * @param addrlen size of addr
 221  * @param errCode value of errno (on errors receiving)
 222  */
 223 static void
 224 receive_helper (void *cls,
 225                 const void *buf,
 226                 size_t available,
 227                 const struct sockaddr *addr, socklen_t addrlen, int errCode)
 228 {
 229   struct GNUNET_CLIENT_Connection *conn = cls;
 230   struct GNUNET_TIME_Relative remaining;
 231
 232   GNUNET_assert (conn->msg_complete == GNUNET_NO);
 233   conn->receiver_task = GNUNET_SCHEDULER_NO_PREREQUISITE_TASK;
 234
 235   if ((available == 0) || (conn->sock == NULL) || (errCode != 0))
 236     {
 237       /* signal timeout! */
 238       if (conn->receiver_handler != NULL)
 239         {
 240           conn->receiver_handler (conn->receiver_handler_cls, NULL);
 241           conn->receiver_handler = NULL;
 242         }
 243       return;
 244     }
 245
 246   /* FIXME: optimize for common fast case where buf contains the
 247      entire message and we need no copying... */
 248
 249
 250   /* slow path: append to array */
 251   if (conn->received_size < conn->received_pos + available)
 252     GNUNET_array_grow (conn->received_buf,
 253                        conn->received_size, conn->received_pos + available);
 254   memcpy (&conn->received_buf[conn->received_pos], buf, available);
 255   conn->received_pos += available;
 256   check_complete (conn);
 257   /* check for timeout */
 258   remaining = GNUNET_TIME_absolute_get_remaining (conn->receive_timeout);
 259   if (remaining.value == 0)
 260     {
 261       /* signal timeout! */
 262       conn->receiver_handler (conn->receiver_handler_cls, NULL);
 263       return;
 264     }
 265   /* back to receive -- either for more data or to call callback! */
 266   GNUNET_CLIENT_receive (conn,
 267                          conn->receiver_handler,
 268                          conn->receiver_handler_cls, remaining);
 269 }
 270
 271
 272 /**
 273  * Continuation to call the receive callback.
 274  */
 275 static void
 276 receive_task (void *scls, const struct GNUNET_SCHEDULER_TaskContext *tc)
 277 {
 278   struct GNUNET_CLIENT_Connection *sock = scls;
 279   const struct GNUNET_MessageHeader *cmsg;
 280   struct GNUNET_MessageHeader *msg;
 281   GNUNET_CLIENT_MessageHandler handler = sock->receiver_handler;
 282   void *cls = sock->receiver_handler_cls;
 283   uint16_t msize;
 284
 285   GNUNET_assert (GNUNET_YES == sock->msg_complete);
 286   sock->receiver_task = GNUNET_SCHEDULER_NO_PREREQUISITE_TASK;
 287   cmsg = (const struct GNUNET_MessageHeader *) sock->received_buf;
 288   msize = ntohs (cmsg->size);
 289   GNUNET_assert (sock->received_pos >= msize);
 290   msg = GNUNET_malloc (msize);
 291   memcpy (msg, cmsg, msize);
 292   memmove (sock->received_buf,
 293            &sock->received_buf[msize], sock->received_pos - msize);
 294   sock->received_pos -= msize;
 295   sock->msg_complete = GNUNET_NO;
 296   sock->receiver_handler = NULL;
 297   check_complete (sock);
 298   handler (cls, msg);
 299   GNUNET_free (msg);
 300 }
 301
 302
 303 /**
 304  * Read from the service.
 305  *
 306  * @param sched scheduler to use
 307  * @param sock the service
 308  * @param handler function to call with the message
 309  * @param cls closure for handler
 310  * @param timeout how long to wait until timing out
 311  */
 312 void
 313 GNUNET_CLIENT_receive (struct GNUNET_CLIENT_Connection *sock,
 314                        GNUNET_CLIENT_MessageHandler handler,
 315                        void *cls, struct GNUNET_TIME_Relative timeout)
 316 {
 317   if (sock->sock == NULL)
 318     {
 319       /* already disconnected, fail instantly! */
 320       GNUNET_break (0);         /* this should not happen in well-written code! */
 321       handler (cls, NULL);
 322       return;
 323     }
 324   GNUNET_assert (sock->receiver_task ==
 325                  GNUNET_SCHEDULER_NO_PREREQUISITE_TASK);
 326   sock->receiver_handler = handler;
 327   sock->receiver_handler_cls = cls;
 328   sock->receive_timeout = GNUNET_TIME_relative_to_absolute (timeout);
 329   if (GNUNET_YES == sock->msg_complete)
 330     sock->receiver_task = GNUNET_SCHEDULER_add_after (sock->sched,
 331                                                       GNUNET_YES,
 332                                                       GNUNET_SCHEDULER_PRIORITY_KEEP,
 333                                                       GNUNET_SCHEDULER_NO_PREREQUISITE_TASK,
 334                                                       &receive_task, sock);
 335   else
 336     sock->receiver_task = GNUNET_NETWORK_receive (sock->sock,
 337                                                   GNUNET_SERVER_MAX_MESSAGE_SIZE,
 338                                                   timeout,
 339                                                   &receive_helper, sock);
 340 }
 341
 342
 343 static size_t
 344 write_shutdown (void *cls, size_t size, void *buf)
 345 {
 346   struct GNUNET_MessageHeader *msg;
 347
 348   if (size < sizeof (struct GNUNET_MessageHeader))
 349     return 0;                   /* client disconnected */
 350   msg = (struct GNUNET_MessageHeader *) buf;
 351   msg->type = htons (GNUNET_MESSAGE_TYPE_SHUTDOWN);
 352   msg->size = htons (sizeof (struct GNUNET_MessageHeader));
 353   return sizeof (struct GNUNET_MessageHeader);
 354 }
 355
 356
 357 /**
 358  * Request that the service should shutdown.
 359  * Afterwards, the connection should be disconnected.
 360  *
 361  * @param sched scheduler to use
 362  * @param sock the socket connected to the service
 363  */
 364 void
 365 GNUNET_CLIENT_service_shutdown (struct GNUNET_CLIENT_Connection *sock)
 366 {
 367   GNUNET_NETWORK_notify_transmit_ready (sock->sock,
 368                                         sizeof (struct GNUNET_MessageHeader),
 369                                         GNUNET_TIME_UNIT_FOREVER_REL,
 370                                         &write_shutdown, NULL);
 371 }
 372
 373
 374 /**
 375  * Report service unavailable.
 376  */
 377 static void
 378 service_test_error (struct GNUNET_SCHEDULER_Handle *s,
 379                     GNUNET_SCHEDULER_Task task, void *task_cls)
 380 {
 381   GNUNET_SCHEDULER_add_continuation (s,
 382                                      GNUNET_YES,
 383                                      task,
 384                                      task_cls,
 385                                      GNUNET_SCHEDULER_REASON_TIMEOUT);
 386 }
 387
 388
 389 /**
 390  * Receive confirmation from test, service is up.
 391  *
 392  * @param cls closure
 393  * @param msg message received, NULL on timeout or fatal error
 394  */
 395 static void
 396 confirm_handler (void *cls, const struct GNUNET_MessageHeader *msg)
 397 {
 398   struct GNUNET_CLIENT_Connection *conn = cls;
 399   /* We may want to consider looking at the reply in more
 400      detail in the future, for example, is this the
 401      correct service? FIXME! */
 402   if (msg != NULL)
 403     {
 404 #if DEBUG_CLIENT
 405       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 406                   "Received confirmation that service is running.\n");
 407 #endif
 408       GNUNET_SCHEDULER_add_continuation (conn->sched,
 409                                          GNUNET_YES,
 410                                          conn->test_cb,
 411                                          conn->test_cb_cls,
 412                                          GNUNET_SCHEDULER_REASON_PREREQ_DONE);
 413     }
 414   else
 415     {
 416       service_test_error (conn->sched, conn->test_cb, conn->test_cb_cls);
 417     }
 418   GNUNET_CLIENT_disconnect (conn);
 419 }
 420
 421
 422 static size_t
 423 write_test (void *cls, size_t size, void *buf)
 424 {
 425   struct GNUNET_MessageHeader *msg;
 426
 427   if (size < sizeof (struct GNUNET_MessageHeader))
 428     {
 429 #if DEBUG_CLIENT
 430       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 431                   _("Failure to transmit TEST request.\n"));
 432 #endif
 433       return 0;                 /* client disconnected */
 434     }
 435 #if DEBUG_CLIENT
 436   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, _("Transmitting TEST request.\n"));
 437 #endif
 438   msg = (struct GNUNET_MessageHeader *) buf;
 439   msg->type = htons (GNUNET_MESSAGE_TYPE_TEST);
 440   msg->size = htons (sizeof (struct GNUNET_MessageHeader));
 441   return sizeof (struct GNUNET_MessageHeader);
 442 }
 443
 444
 445 /**
 446  * Wait until the service is running.
 447  *
 448  * @param sched scheduler to use
 449  * @param service name of the service to wait for
 450  * @param cfg configuration to use
 451  * @param timeout how long to wait at most in ms
 452  * @param task task to run if service is running
 453  *        (reason will be "PREREQ_DONE" (service running)
 454  *         or "TIMEOUT" (service not known to be running))
 455  * @param task_cls closure for task
 456  */
 457 void
 458 GNUNET_CLIENT_service_test (struct GNUNET_SCHEDULER_Handle *sched,
 459                             const char *service,
 460                             struct GNUNET_CONFIGURATION_Handle *cfg,
 461                             struct GNUNET_TIME_Relative timeout,
 462                             GNUNET_SCHEDULER_Task task, void *task_cls)
 463 {
 464   struct GNUNET_CLIENT_Connection *conn;
 465
 466 #if DEBUG_CLIENT
 467   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 468               "Testing if service `%s' is running.\n", service);
 469 #endif
 470   conn = GNUNET_CLIENT_connect (sched, service, cfg);
 471   if (conn == NULL)
 472     {
 473       GNUNET_log (GNUNET_ERROR_TYPE_INFO,
 474                   _
 475                   ("Could not connect to service `%s', must not be running.\n"),
 476                   service);
 477       service_test_error (sched, task, task_cls);
 478       return;
 479     }
 480   conn->test_cb = task;
 481   conn->test_cb_cls = task_cls;
 482   if (NULL ==
 483       GNUNET_NETWORK_notify_transmit_ready (conn->sock,
 484                                             sizeof (struct
 485                                                     GNUNET_MessageHeader),
 486                                             timeout, &write_test, NULL))
 487     {
 488       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
 489                   _("Failure to transmit request to service `%s'\n"),
 490                   service);
 491       service_test_error (sched, task, task_cls);
 492       GNUNET_CLIENT_disconnect (conn);
 493       return;
 494     }
 495   GNUNET_CLIENT_receive (conn, &confirm_handler, conn, timeout);
 496 }
 497
 498
 499 /**
 500  * Ask the client to call us once the specified number of bytes
 501  * are free in the transmission buffer.  May call the notify
 502  * method immediately if enough space is available.
 503  *
 504  * @param client connection to the service
 505  * @param size number of bytes to send
 506  * @param timeout after how long should we give up (and call
 507  *        notify with buf NULL and size 0)?
 508  * @param notify function to call
 509  * @param notify_cls closure for notify
 510  * @return NULL if our buffer will never hold size bytes,
 511  *         a handle if the notify callback was queued (can be used to cancel)
 512  */
 513 struct GNUNET_NETWORK_TransmitHandle *
 514 GNUNET_CLIENT_notify_transmit_ready (struct GNUNET_CLIENT_Connection *sock,
 515                                      size_t size,
 516                                      struct GNUNET_TIME_Relative timeout,
 517                                      GNUNET_NETWORK_TransmitReadyNotify
 518                                      notify, void *notify_cls)
 519 {
 520   return GNUNET_NETWORK_notify_transmit_ready (sock->sock,
 521                                                size,
 522                                                timeout, notify, notify_cls);
 523 }
 524
 525
 526 /*  end of client.c */