src/util/client.c

   1 /*
   2      This file is part of GNUnet.
   3      Copyright (C) 2001-2016 GNUnet e.V.
   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 3, 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., 51 Franklin Street, Fifth Floor,
  18      Boston, MA 02110-1301, 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 #include "platform.h"
  30 #include "gnunet_protocols.h"
  31 #include "gnunet_util_lib.h"
  32 #include "gnunet_resolver_service.h"
  33 #include "gnunet_socks.h"
  34
  35
  36 #define LOG(kind,...) GNUNET_log_from (kind, "util-client",__VA_ARGS__)
  37
  38 /**
  39  * Timeout we use on TCP connect before trying another
  40  * result from the DNS resolver.  Actual value used
  41  * is this value divided by the number of address families.
  42  * Default is 5s.
  43  */
  44 #define CONNECT_RETRY_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)
  45
  46
  47
  48 /**
  49  * Internal state for a client connected to a GNUnet service.
  50  */
  51 struct ClientState;
  52
  53
  54 /**
  55  * During connect, we try multiple possible IP addresses
  56  * to find out which one might work.
  57  */
  58 struct AddressProbe
  59 {
  60
  61   /**
  62    * This is a linked list.
  63    */
  64   struct AddressProbe *next;
  65
  66   /**
  67    * This is a doubly-linked list.
  68    */
  69   struct AddressProbe *prev;
  70
  71   /**
  72    * The address; do not free (allocated at the end of this struct).
  73    */
  74   const struct sockaddr *addr;
  75
  76   /**
  77    * Underlying OS's socket.
  78    */
  79   struct GNUNET_NETWORK_Handle *sock;
  80
  81   /**
  82    * Connection for which we are probing.
  83    */
  84   struct ClientState *cstate;
  85
  86   /**
  87    * Lenth of addr.
  88    */
  89   socklen_t addrlen;
  90
  91   /**
  92    * Task waiting for the connection to finish connecting.
  93    */
  94   struct GNUNET_SCHEDULER_Task *task;
  95 };
  96
  97
  98 /**
  99  * Internal state for a client connected to a GNUnet service.
 100  */
 101 struct ClientState
 102 {
 103
 104   /**
 105    * The connection handle, NULL if not live
 106    */
 107   struct GNUNET_NETWORK_Handle *sock;
 108
 109   /**
 110    * Handle to a pending DNS lookup request, NULL if DNS is finished.
 111    */
 112   struct GNUNET_RESOLVER_RequestHandle *dns_active;
 113
 114   /**
 115    * Our configuration.
 116    */
 117   const struct GNUNET_CONFIGURATION_Handle *cfg;
 118
 119   /**
 120    * Linked list of sockets we are currently trying out
 121    * (during connect).
 122    */
 123   struct AddressProbe *ap_head;
 124
 125   /**
 126    * Linked list of sockets we are currently trying out
 127    * (during connect).
 128    */
 129   struct AddressProbe *ap_tail;
 130
 131   /**
 132    * Name of the service we interact with.
 133    */
 134   char *service_name;
 135
 136   /**
 137    * Hostname, if any.
 138    */
 139   char *hostname;
 140
 141   /**
 142    * Next message to transmit to the service. NULL for none.
 143    */
 144   const struct GNUNET_MessageHeader *msg;
 145
 146   /**
 147    * Task for trying to connect to the service.
 148    */
 149   struct GNUNET_SCHEDULER_Task *retry_task;
 150
 151   /**
 152    * Task for sending messages to the service.
 153    */
 154   struct GNUNET_SCHEDULER_Task *send_task;
 155
 156   /**
 157    * Task for sending messages to the service.
 158    */
 159   struct GNUNET_SCHEDULER_Task *recv_task;
 160
 161   /**
 162    * Tokenizer for inbound messages.
 163    */
 164   struct GNUNET_MessageStreamTokenizer *mst;
 165
 166   /**
 167    * Message queue under our control.
 168    */
 169   struct GNUNET_MQ_Handle *mq;
 170
 171   /**
 172    * Timeout for receiving a response (absolute time).
 173    */
 174   struct GNUNET_TIME_Absolute receive_timeout;
 175
 176   /**
 177    * Current value for our incremental back-off (for
 178    * connect re-tries).
 179    */
 180   struct GNUNET_TIME_Relative back_off;
 181
 182   /**
 183    * TCP port (0 for disabled).
 184    */
 185   unsigned long long port;
 186
 187   /**
 188    * Offset in the message where we are for transmission.
 189    */
 190   size_t msg_off;
 191
 192   /**
 193    * How often have we tried to connect?
 194    */
 195   unsigned int attempts;
 196
 197   /**
 198    * Are we supposed to die?  #GNUNET_SYSERR if destruction must be
 199    * deferred, #GNUNET_NO by default, #GNUNET_YES if destruction was
 200    * deferred.
 201    */
 202   int in_destroy;
 203
 204 };
 205
 206
 207 /**
 208  * Try to connect to the service.
 209  *
 210  * @param cls the `struct ClientState` to try to connect to the service
 211  */
 212 static void
 213 start_connect (void *cls);
 214
 215
 216 /**
 217  * We've failed for good to establish a connection (timeout or
 218  * no more addresses to try).
 219  *
 220  * @param cstate the connection we tried to establish
 221  */
 222 static void
 223 connect_fail_continuation (struct ClientState *cstate)
 224 {
 225   GNUNET_break (NULL == cstate->ap_head);
 226   GNUNET_break (NULL == cstate->ap_tail);
 227   GNUNET_break (NULL == cstate->dns_active);
 228   GNUNET_break (NULL == cstate->sock);
 229   GNUNET_assert (NULL == cstate->send_task);
 230   GNUNET_assert (NULL == cstate->recv_task);
 231   // GNUNET_assert (NULL == cstate->proxy_handshake);
 232
 233   cstate->back_off = GNUNET_TIME_STD_BACKOFF (cstate->back_off);
 234   LOG (GNUNET_ERROR_TYPE_DEBUG,
 235        "Failed to establish connection to `%s', no further addresses to try, will try again in %s.\n",
 236        cstate->service_name,
 237        GNUNET_STRINGS_relative_time_to_string (cstate->back_off,
 238                                                GNUNET_YES));
 239   cstate->retry_task
 240     = GNUNET_SCHEDULER_add_delayed (cstate->back_off,
 241                                     &start_connect,
 242                                     cstate);
 243 }
 244
 245
 246 /**
 247  * We are ready to send a message to the service.
 248  *
 249  * @param cls the `struct ClientState` with the `msg` to transmit
 250  */
 251 static void
 252 transmit_ready (void *cls)
 253 {
 254   struct ClientState *cstate = cls;
 255   ssize_t ret;
 256   size_t len;
 257   const char *pos;
 258   int notify_in_flight;
 259
 260   cstate->send_task = NULL;
 261   pos = (const char *) cstate->msg;
 262   len = ntohs (cstate->msg->size);
 263   GNUNET_assert (cstate->msg_off < len);
 264   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 265               "client: message of type %u trying to send with socket %p (MQ: %p\n",
 266               ntohs(cstate->msg->type),
 267               cstate->sock,
 268               cstate->mq);
 269
 270  RETRY:
 271   ret = GNUNET_NETWORK_socket_send (cstate->sock,
 272                                     &pos[cstate->msg_off],
 273                                     len - cstate->msg_off);
 274   if (-1 == ret)
 275   {
 276     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
 277                 "client: error during sending message of type %u\n", ntohs(cstate->msg->type));
 278     if (EINTR == errno){
 279       GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 280                   "client: retrying message of type %u\n",
 281                   ntohs(cstate->msg->type));
 282       goto RETRY;
 283     }
 284     GNUNET_MQ_inject_error (cstate->mq,
 285                             GNUNET_MQ_ERROR_WRITE);
 286     return;
 287   }
 288   notify_in_flight = (0 == cstate->msg_off);
 289   cstate->msg_off += ret;
 290   if (cstate->msg_off < len)
 291   {
 292     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 293                 "client: rescheduling message of type %u\n",
 294                 ntohs(cstate->msg->type));
 295     cstate->send_task
 296       = GNUNET_SCHEDULER_add_write_net (GNUNET_TIME_UNIT_FOREVER_REL,
 297                                         cstate->sock,
 298                                         &transmit_ready,
 299                                         cstate);
 300     if (notify_in_flight)
 301       GNUNET_MQ_impl_send_in_flight (cstate->mq);
 302     return;
 303   }
 304   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 305               "client: sending message of type %u successful\n",
 306               ntohs(cstate->msg->type));
 307   cstate->msg = NULL;
 308   GNUNET_MQ_impl_send_continue (cstate->mq);
 309 }
 310
 311
 312 /**
 313  * We have received a full message, pass to the MQ dispatcher.
 314  * Called by the tokenizer via #receive_ready().
 315  *
 316  * @param cls the `struct ClientState`
 317  * @param msg message we received.
 318  * @return #GNUNET_OK on success,
 319  *     #GNUNET_NO to stop further processing due to disconnect (no error)
 320  *     #GNUNET_SYSERR to stop further processing due to error
 321  */
 322 static int
 323 recv_message (void *cls,
 324               const struct GNUNET_MessageHeader *msg)
 325 {
 326   struct ClientState *cstate = cls;
 327
 328   if (GNUNET_YES == cstate->in_destroy)
 329     return GNUNET_NO;
 330   LOG (GNUNET_ERROR_TYPE_DEBUG,
 331        "Received message of type %u and size %u from %s\n",
 332        ntohs (msg->type),
 333        ntohs (msg->size),
 334        cstate->service_name);
 335   GNUNET_MQ_inject_message (cstate->mq,
 336                             msg);
 337   if (GNUNET_YES == cstate->in_destroy)
 338     return GNUNET_NO;
 339   return GNUNET_OK;
 340 }
 341
 342
 343 /**
 344  * Cancel all remaining connect attempts
 345  *
 346  * @param cstate handle of the client state to process
 347  */
 348 static void
 349 cancel_aps (struct ClientState *cstate)
 350 {
 351   struct AddressProbe *pos;
 352
 353   while (NULL != (pos = cstate->ap_head))
 354   {
 355     GNUNET_break (GNUNET_OK ==
 356                   GNUNET_NETWORK_socket_close (pos->sock));
 357     GNUNET_SCHEDULER_cancel (pos->task);
 358     GNUNET_CONTAINER_DLL_remove (cstate->ap_head,
 359                                  cstate->ap_tail,
 360                                  pos);
 361     GNUNET_free (pos);
 362   }
 363 }
 364
 365
 366 /**
 367  * Implement the destruction of a message queue.  Implementations must
 368  * not free @a mq, but should take care of @a impl_state.
 369  *
 370  * @param mq the message queue to destroy
 371  * @param impl_state our `struct ClientState`
 372  */
 373 static void
 374 connection_client_destroy_impl (struct GNUNET_MQ_Handle *mq,
 375                                 void *impl_state)
 376 {
 377   struct ClientState *cstate = impl_state;
 378
 379   if (GNUNET_SYSERR == cstate->in_destroy)
 380   {
 381     /* defer destruction */
 382     cstate->in_destroy = GNUNET_YES;
 383     cstate->mq = NULL;
 384     return;
 385   }
 386   if (NULL != cstate->dns_active)
 387     GNUNET_RESOLVER_request_cancel (cstate->dns_active);
 388   if (NULL != cstate->send_task)
 389     GNUNET_SCHEDULER_cancel (cstate->send_task);
 390   if (NULL != cstate->recv_task)
 391     GNUNET_SCHEDULER_cancel (cstate->recv_task);
 392   if (NULL != cstate->retry_task)
 393     GNUNET_SCHEDULER_cancel (cstate->retry_task);
 394   if (NULL != cstate->sock){
 395     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 396                 "client: destroying socket: %p\n",
 397                 cstate->sock);
 398     GNUNET_NETWORK_socket_close (cstate->sock);
 399   }
 400   cancel_aps (cstate);
 401   GNUNET_free (cstate->service_name);
 402   GNUNET_free_non_null (cstate->hostname);
 403   GNUNET_MST_destroy (cstate->mst);
 404   GNUNET_free (cstate);
 405 }
 406
 407
 408 /**
 409  * This function is called once we have data ready to read.
 410  *
 411  * @param cls `struct ClientState` with connection to read from
 412  */
 413 static void
 414 receive_ready (void *cls)
 415 {
 416   struct ClientState *cstate = cls;
 417   int ret;
 418
 419   cstate->recv_task = NULL;
 420   cstate->in_destroy = GNUNET_SYSERR;
 421   ret = GNUNET_MST_read (cstate->mst,
 422                          cstate->sock,
 423                          GNUNET_NO,
 424                          GNUNET_NO);
 425   if (GNUNET_SYSERR == ret)
 426   {
 427     if (NULL != cstate->mq)
 428       GNUNET_MQ_inject_error (cstate->mq,
 429                               GNUNET_MQ_ERROR_READ);
 430     if (GNUNET_YES == cstate->in_destroy)
 431       connection_client_destroy_impl (cstate->mq,
 432                                       cstate);
 433     return;
 434   }
 435   if (GNUNET_YES == cstate->in_destroy)
 436   {
 437     connection_client_destroy_impl (cstate->mq,
 438                                     cstate);
 439     return;
 440   }
 441   cstate->in_destroy = GNUNET_NO;
 442   cstate->recv_task
 443     = GNUNET_SCHEDULER_add_read_net (GNUNET_TIME_UNIT_FOREVER_REL,
 444                                      cstate->sock,
 445                                      &receive_ready,
 446                                      cstate);
 447 }
 448
 449
 450 /**
 451  * We've succeeded in establishing a connection.
 452  *
 453  * @param cstate the connection we tried to establish
 454  */
 455 static void
 456 connect_success_continuation (struct ClientState *cstate)
 457 {
 458   GNUNET_assert (NULL == cstate->recv_task);
 459   cstate->recv_task
 460     = GNUNET_SCHEDULER_add_read_net (GNUNET_TIME_UNIT_FOREVER_REL,
 461                                      cstate->sock,
 462                                      &receive_ready,
 463                                      cstate);
 464   if (NULL != cstate->msg)
 465   {
 466     GNUNET_assert (NULL == cstate->send_task);
 467     cstate->send_task
 468       = GNUNET_SCHEDULER_add_write_net (GNUNET_TIME_UNIT_FOREVER_REL,
 469                                         cstate->sock,
 470                                         &transmit_ready,
 471                                         cstate);
 472   }
 473 }
 474
 475
 476 /**
 477  * Try connecting to the server using UNIX domain sockets.
 478  *
 479  * @param service_name name of service to connect to
 480  * @param cfg configuration to use
 481  * @return NULL on error, socket connected to UNIX otherwise
 482  */
 483 static struct GNUNET_NETWORK_Handle *
 484 try_unixpath (const char *service_name,
 485               const struct GNUNET_CONFIGURATION_Handle *cfg)
 486 {
 487 #if AF_UNIX
 488   struct GNUNET_NETWORK_Handle *sock;
 489   char *unixpath;
 490   struct sockaddr_un s_un;
 491
 492   unixpath = NULL;
 493   if ((GNUNET_OK ==
 494        GNUNET_CONFIGURATION_get_value_filename (cfg,
 495                                                 service_name,
 496                                                 "UNIXPATH",
 497                                                 &unixpath)) &&
 498       (0 < strlen (unixpath)))
 499   {
 500     /* We have a non-NULL unixpath, need to validate it */
 501     if (strlen (unixpath) >= sizeof (s_un.sun_path))
 502     {
 503       LOG (GNUNET_ERROR_TYPE_WARNING,
 504            _("UNIXPATH `%s' too long, maximum length is %llu\n"),
 505            unixpath,
 506            (unsigned long long) sizeof (s_un.sun_path));
 507       unixpath = GNUNET_NETWORK_shorten_unixpath (unixpath);
 508       LOG (GNUNET_ERROR_TYPE_INFO,
 509            _("Using `%s' instead\n"),
 510            unixpath);
 511       if (NULL == unixpath)
 512         return NULL;
 513     }
 514     memset (&s_un,
 515             0,
 516             sizeof (s_un));
 517     s_un.sun_family = AF_UNIX;
 518     strncpy (s_un.sun_path,
 519              unixpath,
 520              sizeof (s_un.sun_path) - 1);
 521 #ifdef LINUX
 522     {
 523       int abstract;
 524
 525       abstract = GNUNET_CONFIGURATION_get_value_yesno (cfg,
 526                                                        "TESTING",
 527                                                        "USE_ABSTRACT_SOCKETS");
 528       if (GNUNET_YES == abstract)
 529         s_un.sun_path[0] = '\0';
 530     }
 531 #endif
 532 #if HAVE_SOCKADDR_UN_SUN_LEN
 533     s_un.sun_len = (u_char) sizeof (struct sockaddr_un);
 534 #endif
 535     sock = GNUNET_NETWORK_socket_create (AF_UNIX,
 536                                          SOCK_STREAM,
 537                                          0);
 538     if ( (NULL != sock) &&
 539          ( (GNUNET_OK ==
 540             GNUNET_NETWORK_socket_connect (sock,
 541                                            (struct sockaddr *) &s_un,
 542                                            sizeof (s_un))) ||
 543            (EINPROGRESS == errno) ) )
 544     {
 545       LOG (GNUNET_ERROR_TYPE_DEBUG,
 546            "Successfully connected to unixpath `%s'!\n",
 547            unixpath);
 548       GNUNET_free (unixpath);
 549       return sock;
 550     }
 551     if (NULL != sock)
 552       GNUNET_NETWORK_socket_close (sock);
 553   }
 554   GNUNET_free_non_null (unixpath);
 555 #endif
 556   return NULL;
 557 }
 558
 559
 560 /**
 561  * Scheduler let us know that we're either ready to write on the
 562  * socket OR connect timed out.  Do the right thing.
 563  *
 564  * @param cls the `struct AddressProbe *` with the address that we are probing
 565  */
 566 static void
 567 connect_probe_continuation (void *cls)
 568 {
 569   struct AddressProbe *ap = cls;
 570   struct ClientState *cstate = ap->cstate;
 571   const struct GNUNET_SCHEDULER_TaskContext *tc;
 572   int error;
 573   socklen_t len;
 574
 575   ap->task = NULL;
 576   GNUNET_assert (NULL != ap->sock);
 577   GNUNET_CONTAINER_DLL_remove (cstate->ap_head,
 578                                cstate->ap_tail,
 579                                ap);
 580   len = sizeof (error);
 581   error = 0;
 582   tc = GNUNET_SCHEDULER_get_task_context ();
 583   if ( (0 == (tc->reason & GNUNET_SCHEDULER_REASON_WRITE_READY)) ||
 584        (GNUNET_OK !=
 585         GNUNET_NETWORK_socket_getsockopt (ap->sock,
 586                                           SOL_SOCKET,
 587                                           SO_ERROR,
 588                                           &error,
 589                                           &len)) ||
 590        (0 != error) )
 591   {
 592     GNUNET_break (GNUNET_OK ==
 593                   GNUNET_NETWORK_socket_close (ap->sock));
 594     GNUNET_free (ap);
 595     if ( (NULL == cstate->ap_head) &&
 596          //      (NULL == cstate->proxy_handshake) &&
 597          (NULL == cstate->dns_active) )
 598       connect_fail_continuation (cstate);
 599     return;
 600   }
 601   LOG (GNUNET_ERROR_TYPE_DEBUG,
 602        "Connection to `%s' succeeded!\n",
 603        cstate->service_name);
 604   /* trigger jobs that waited for the connection */
 605   GNUNET_assert (NULL == cstate->sock);
 606   cstate->sock = ap->sock;
 607   GNUNET_free (ap);
 608   cancel_aps (cstate);
 609   connect_success_continuation (cstate);
 610 }
 611
 612
 613 /**
 614  * Try to establish a connection given the specified address.
 615  * This function is called by the resolver once we have a DNS reply.
 616  *
 617  * @param cls our `struct ClientState *`
 618  * @param addr address to try, NULL for "last call"
 619  * @param addrlen length of @a addr
 620  */
 621 static void
 622 try_connect_using_address (void *cls,
 623                            const struct sockaddr *addr,
 624                            socklen_t addrlen)
 625 {
 626   struct ClientState *cstate = cls;
 627   struct AddressProbe *ap;
 628
 629   if (NULL == addr)
 630   {
 631     cstate->dns_active = NULL;
 632     if ( (NULL == cstate->ap_head) &&
 633          //  (NULL == cstate->proxy_handshake) &&
 634          (NULL == cstate->sock) )
 635       connect_fail_continuation (cstate);
 636     return;
 637   }
 638   if (NULL != cstate->sock)
 639     return;                     /* already connected */
 640   /* try to connect */
 641   LOG (GNUNET_ERROR_TYPE_DEBUG,
 642        "Trying to connect using address `%s:%u'\n",
 643        GNUNET_a2s (addr,
 644                    addrlen),
 645        cstate->port);
 646   ap = GNUNET_malloc (sizeof (struct AddressProbe) + addrlen);
 647   ap->addr = (const struct sockaddr *) &ap[1];
 648   GNUNET_memcpy (&ap[1],
 649                  addr,
 650                  addrlen);
 651   ap->addrlen = addrlen;
 652   ap->cstate = cstate;
 653
 654   switch (ap->addr->sa_family)
 655   {
 656   case AF_INET:
 657     ((struct sockaddr_in *) ap->addr)->sin_port = htons (cstate->port);
 658     break;
 659   case AF_INET6:
 660     ((struct sockaddr_in6 *) ap->addr)->sin6_port = htons (cstate->port);
 661     break;
 662   default:
 663     GNUNET_break (0);
 664     GNUNET_free (ap);
 665     return;                     /* not supported by us */
 666   }
 667   ap->sock = GNUNET_NETWORK_socket_create (ap->addr->sa_family,
 668                                            SOCK_STREAM,
 669                                            0);
 670   if (NULL == ap->sock)
 671   {
 672     GNUNET_free (ap);
 673     return;                     /* not supported by OS */
 674   }
 675   if ( (GNUNET_OK !=
 676         GNUNET_NETWORK_socket_connect (ap->sock,
 677                                        ap->addr,
 678                                        ap->addrlen)) &&
 679        (EINPROGRESS != errno) )
 680   {
 681     /* maybe refused / unsupported address, try next */
 682     GNUNET_log_strerror (GNUNET_ERROR_TYPE_INFO,
 683                          "connect");
 684     GNUNET_break (GNUNET_OK ==
 685                   GNUNET_NETWORK_socket_close (ap->sock));
 686     GNUNET_free (ap);
 687     return;
 688   }
 689   GNUNET_CONTAINER_DLL_insert (cstate->ap_head,
 690                                cstate->ap_tail,
 691                                ap);
 692   ap->task = GNUNET_SCHEDULER_add_write_net (CONNECT_RETRY_TIMEOUT,
 693                                              ap->sock,
 694                                              &connect_probe_continuation,
 695                                              ap);
 696 }
 697
 698
 699 /**
 700  * Test whether the configuration has proper values for connection
 701  * (UNIXPATH || (PORT && HOSTNAME)).
 702  *
 703  * @param service_name name of service to connect to
 704  * @param cfg configuration to use
 705  * @return #GNUNET_OK if the configuration is valid, #GNUNET_SYSERR if not
 706  */
 707 static int
 708 test_service_configuration (const char *service_name,
 709                             const struct GNUNET_CONFIGURATION_Handle *cfg)
 710 {
 711   int ret = GNUNET_SYSERR;
 712   char *hostname = NULL;
 713   unsigned long long port;
 714 #if AF_UNIX
 715   char *unixpath = NULL;
 716
 717   if ((GNUNET_OK ==
 718        GNUNET_CONFIGURATION_get_value_filename (cfg,
 719                                                 service_name,
 720                                                 "UNIXPATH",
 721                                                 &unixpath)) &&
 722       (0 < strlen (unixpath)))
 723     ret = GNUNET_OK;
 724   GNUNET_free_non_null (unixpath);
 725 #endif
 726
 727   if ( (GNUNET_YES ==
 728         GNUNET_CONFIGURATION_have_value (cfg,
 729                                          service_name,
 730                                          "PORT")) &&
 731        (GNUNET_OK ==
 732         GNUNET_CONFIGURATION_get_value_number (cfg,
 733                                                service_name,
 734                                                "PORT",
 735                                                &port)) &&
 736        (port <= 65535) &&
 737        (0 != port) &&
 738        (GNUNET_OK ==
 739         GNUNET_CONFIGURATION_get_value_string (cfg,
 740                                                service_name,
 741                                                "HOSTNAME",
 742                                                &hostname)) &&
 743        (0 != strlen (hostname)) )
 744     ret = GNUNET_OK;
 745   GNUNET_free_non_null (hostname);
 746   return ret;
 747 }
 748
 749
 750 /**
 751  * Try to connect to the service.
 752  *
 753  * @param cls the `struct ClientState` to try to connect to the service
 754  */
 755 static void
 756 start_connect (void *cls)
 757 {
 758   struct ClientState *cstate = cls;
 759
 760   cstate->retry_task = NULL;
 761 #if 0
 762   /* Never use a local source if a proxy is configured */
 763   if (GNUNET_YES ==
 764       GNUNET_SOCKS_check_service (cstate->service_name,
 765                                   cstate->cfg))
 766   {
 767     socks_connect (cstate);
 768     return;
 769   }
 770 #endif
 771
 772   if ( (0 == (cstate->attempts++ % 2)) ||
 773        (0 == cstate->port) ||
 774        (NULL == cstate->hostname) )
 775   {
 776     /* on even rounds, try UNIX first, or always
 777        if we do not have a DNS name and TCP port. */
 778     cstate->sock = try_unixpath (cstate->service_name,
 779                                  cstate->cfg);
 780     if (NULL != cstate->sock)
 781     {
 782       connect_success_continuation (cstate);
 783       return;
 784     }
 785   }
 786   if ( (NULL == cstate->hostname) ||
 787        (0 == cstate->port) )
 788   {
 789     /* All options failed. Boo! */
 790     connect_fail_continuation (cstate);
 791     return;
 792   }
 793   cstate->dns_active
 794     = GNUNET_RESOLVER_ip_get (cstate->hostname,
 795                               AF_UNSPEC,
 796                               CONNECT_RETRY_TIMEOUT,
 797                               &try_connect_using_address,
 798                               cstate);
 799 }
 800
 801
 802 /**
 803  * Implements the transmission functionality of a message queue.
 804  *
 805  * @param mq the message queue
 806  * @param msg the message to send
 807  * @param impl_state our `struct ClientState`
 808  */
 809 static void
 810 connection_client_send_impl (struct GNUNET_MQ_Handle *mq,
 811                              const struct GNUNET_MessageHeader *msg,
 812                              void *impl_state)
 813 {
 814   struct ClientState *cstate = impl_state;
 815
 816   /* only one message at a time allowed */
 817   GNUNET_assert (NULL == cstate->msg);
 818   GNUNET_assert (NULL == cstate->send_task);
 819   cstate->msg = msg;
 820   cstate->msg_off = 0;
 821   if (NULL == cstate->sock){
 822     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 823                 "client: message of type %u waiting for socket\n",
 824                 ntohs(msg->type));
 825     return; /* still waiting for connection */
 826    }
 827   cstate->send_task
 828     = GNUNET_SCHEDULER_add_write_net (GNUNET_TIME_UNIT_FOREVER_REL,
 829                                       cstate->sock,
 830                                       &transmit_ready,
 831                                       cstate);
 832 }
 833
 834
 835 /**
 836  * Cancel the currently sent message.
 837  *
 838  * @param mq message queue
 839  * @param impl_state our `struct ClientState`
 840  */
 841 static void
 842 connection_client_cancel_impl (struct GNUNET_MQ_Handle *mq,
 843                                void *impl_state)
 844 {
 845   struct ClientState *cstate = impl_state;
 846
 847   GNUNET_assert (NULL != cstate->msg);
 848   GNUNET_assert (0 == cstate->msg_off);
 849   cstate->msg = NULL;
 850   if (NULL != cstate->send_task)
 851   {
 852     GNUNET_SCHEDULER_cancel (cstate->send_task);
 853     cstate->send_task = NULL;
 854   }
 855 }
 856
 857
 858 /**
 859  * Create a message queue to connect to a GNUnet service.
 860  * If handlers are specfied, receive messages from the connection.
 861  *
 862  * @param cfg our configuration
 863  * @param service_name name of the service to connect to
 864  * @param handlers handlers for receiving messages, can be NULL
 865  * @param error_handler error handler
 866  * @param error_handler_cls closure for the @a error_handler
 867  * @return the message queue, NULL on error
 868  */
 869 struct GNUNET_MQ_Handle *
 870 GNUNET_CLIENT_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
 871                        const char *service_name,
 872                        const struct GNUNET_MQ_MessageHandler *handlers,
 873                        GNUNET_MQ_ErrorHandler error_handler,
 874                        void *error_handler_cls)
 875 {
 876   struct ClientState *cstate;
 877
 878   if (GNUNET_OK !=
 879       test_service_configuration (service_name,
 880                                   cfg))
 881     return NULL;
 882   cstate = GNUNET_new (struct ClientState);
 883   cstate->service_name = GNUNET_strdup (service_name);
 884   cstate->cfg = cfg;
 885   cstate->retry_task = GNUNET_SCHEDULER_add_now (&start_connect,
 886                                                  cstate);
 887   cstate->mst = GNUNET_MST_create (&recv_message,
 888                                    cstate);
 889   if (GNUNET_YES ==
 890       GNUNET_CONFIGURATION_have_value (cfg,
 891                                        service_name,
 892                                        "PORT"))
 893   {
 894     if (! ( (GNUNET_OK !=
 895              GNUNET_CONFIGURATION_get_value_number (cfg,
 896                                                     service_name,
 897                                                     "PORT",
 898                                                     &cstate->port)) ||
 899             (cstate->port > 65535) ||
 900             (GNUNET_OK !=
 901              GNUNET_CONFIGURATION_get_value_string (cfg,
 902                                                     service_name,
 903                                                     "HOSTNAME",
 904                                                     &cstate->hostname)) ) &&
 905         (0 == strlen (cstate->hostname)) )
 906     {
 907       GNUNET_free (cstate->hostname);
 908       cstate->hostname = NULL;
 909       LOG (GNUNET_ERROR_TYPE_WARNING,
 910            _("Need a non-empty hostname for service `%s'.\n"),
 911            service_name);
 912     }
 913   }
 914   cstate->mq = GNUNET_MQ_queue_for_callbacks (&connection_client_send_impl,
 915                                               &connection_client_destroy_impl,
 916                                               &connection_client_cancel_impl,
 917                                               cstate,
 918                                               handlers,
 919                                               error_handler,
 920                                               error_handler_cls);
 921   return cstate->mq;
 922 }
 923
 924 /* end of client.c */