path: root/src/core/gnunet-service-core_clients.c

/*
     This file is part of GNUnet.
     Copyright (C) 2009, 2010, 2011 Christian Grothoff (and other contributing authors)

     GNUnet is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published
     by the Free Software Foundation; either version 3, or (at your
     option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
*/

/**
 * @file core/gnunet-service-core_clients.c
 * @brief code for managing interactions with clients of core service
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_statistics_service.h"
#include "gnunet_transport_service.h"
#include "gnunet-service-core.h"
#include "gnunet-service-core_clients.h"
#include "gnunet-service-core_neighbours.h"
#include "gnunet-service-core_sessions.h"
#include "gnunet-service-core_typemap.h"
#include "core.h"


/**
 * How many messages do we queue up at most for optional
 * notifications to a client?  (this can cause notifications
 * about outgoing messages to be dropped).
 */
#define MAX_NOTIFY_QUEUE 1024


/**
 * Data structure for each client connected to the CORE service.
 */
struct GSC_Client
{
  /**
   * Clients are kept in a linked list.
   */
  struct GSC_Client *next;

  /**
   * Clients are kept in a linked list.
   */
  struct GSC_Client *prev;

  /**
   * Handle for the client with the server API.
   */
  struct GNUNET_SERVER_Client *client_handle;

  /**
   * Array of the types of messages this peer cares
   * about (with @e tcnt entries).  Allocated as part
   * of this client struct, do not free!
   */
  const uint16_t *types;

  /**
   * Map of peer identities to active transmission requests of this
   * client to the peer (of type `struct GSC_ClientActiveRequest`).
   */
  struct GNUNET_CONTAINER_MultiPeerMap *requests;

  /**
   * Map containing all peers that this client knows we're connected to.
   */
  struct GNUNET_CONTAINER_MultiPeerMap *connectmap;

  /**
   * Options for messages this client cares about,
   * see GNUNET_CORE_OPTION_ values.
   */
  uint32_t options;

  /**
   * Number of types of incoming messages this client
   * specifically cares about.  Size of the @e types array.
   */
  unsigned int tcnt;

};


/**
 * Big "or" of all client options.
 */
static uint32_t all_client_options;

/**
 * Head of linked list of our clients.
 */
static struct GSC_Client *client_head;

/**
 * Tail of linked list of our clients.
 */
static struct GSC_Client *client_tail;

/**
 * Context for notifications we need to send to our clients.
 */
static struct GNUNET_SERVER_NotificationContext *notifier;

/**
 * Tokenizer for messages received from clients.
 */
static struct GNUNET_SERVER_MessageStreamTokenizer *client_mst;


/**
 * Lookup our client struct given the server's client handle.
 *
 * @param client server client handle to look up
 * @return our client handle for the client
 */
static struct GSC_Client *
find_client (struct GNUNET_SERVER_Client *client)
{
  struct GSC_Client *c;

  c = client_head;
  while ((c != NULL) && (c->client_handle != client))
    c = c->next;
  return c;
}


/**
 * Send a message to one of our clients.
 *
 * @param client target for the message
 * @param msg message to transmit
 * @param can_drop could this message be dropped if the
 *        client's queue is getting too large?
 */
static void
send_to_client (struct GSC_Client *client,
                const struct GNUNET_MessageHeader *msg,
                int can_drop)
{
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Preparing to send %u bytes of message of type %u to client.\n",
              (unsigned int) ntohs (msg->size),
              (unsigned int) ntohs (msg->type));
  GNUNET_SERVER_notification_context_unicast (notifier, client->client_handle,
                                              msg, can_drop);
}


/**
 * Send a message to one of our clients.
 *
 * @param client target for the message
 * @param msg message to transmit
 * @param can_drop could this message be dropped if the
 *        client's queue is getting too large?
 */
void
GSC_CLIENTS_send_to_client (struct GNUNET_SERVER_Client *client,
                            const struct GNUNET_MessageHeader *msg,
                            int can_drop)
{
  struct GSC_Client *c;

  c = find_client (client);
  if (NULL == c)
  {
    GNUNET_break (0);
    return;
  }
  send_to_client (c, msg, can_drop);
}


/**
 * Test if the client is interested in messages of the given type.
 *
 * @param type message type
 * @param c client to test
 * @return #GNUNET_YES if @a c is interested, #GNUNET_NO if not.
 */
static int
type_match (uint16_t type, struct GSC_Client *c)
{
  unsigned int i;

  if (c->tcnt == 0 && c->options != 0)
    return GNUNET_YES;          /* peer without handlers and inbound/outbond
				   callbacks matches ALL */
  for (i = 0; i < c->tcnt; i++)
    if (type == c->types[i])
      return GNUNET_YES;
  return GNUNET_NO;
}


/**
 * Send a message to all of our current clients that have the right
 * options set.
 *
 * @param partner origin (or destination) of the message (used to check that this peer is
 *        known to be connected to the respective client)
 * @param msg message to multicast
 * @param can_drop can this message be discarded if the queue is too long
 * @param options mask to use
 * @param type type of the embedded message, 0 for none
 */
static void
send_to_all_clients (const struct GNUNET_PeerIdentity *partner,
                     const struct GNUNET_MessageHeader *msg,
                     int can_drop,
                     uint32_t options,
                     uint16_t type)
{
  struct GSC_Client *c;
  int tm;

  for (c = client_head; NULL != c; c = c->next)
  {
    tm = type_match (type, c);
    if (!  ( (0 != (c->options & options)) ||
	     ( (0 != (options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) &&
	       (GNUNET_YES == tm) ) ) )
      continue;  /* neither options nor type match permit the message */
    if ( (0 != (options & GNUNET_CORE_OPTION_SEND_HDR_INBOUND)) &&
	 ( (0 != (c->options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) ||
	   (GNUNET_YES == tm) ) )
      continue;
    if ( (0 != (options & GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND)) &&
	 (0 != (c->options & GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND)) )
      continue;
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Sending %u message with %u bytes to client interested in messages of type %u.\n",
		options,
		ntohs (msg->size),
                (unsigned int) type);
    GNUNET_assert ( (0 == (c->options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) ||
		    (GNUNET_YES != tm) ||
		    (GNUNET_YES ==
		     GNUNET_CONTAINER_multipeermap_contains (c->connectmap,
							     partner)) );
    send_to_client (c, msg, can_drop);
  }
}


/**
 * Handle #GNUNET_MESSAGE_TYPE_CORE_INIT request.
 *
 * @param cls unused
 * @param client new client that sent #GNUNET_MESSAGE_TYPE_CORE_INIT
 * @param message the `struct InitMessage` (presumably)
 */
static void
handle_client_init (void *cls,
                    struct GNUNET_SERVER_Client *client,
                    const struct GNUNET_MessageHeader *message)
{
  const struct InitMessage *im;
  struct InitReplyMessage irm;
  struct GSC_Client *c;
  uint16_t msize;
  const uint16_t *types;
  uint16_t *wtypes;
  unsigned int i;

  /* check that we don't have an entry already */
  c = find_client (client);
  if (NULL != c)
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  msize = ntohs (message->size);
  if (msize < sizeof (struct InitMessage))
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  GNUNET_SERVER_notification_context_add (notifier, client);
  im = (const struct InitMessage *) message;
  types = (const uint16_t *) &im[1];
  msize -= sizeof (struct InitMessage);
  c = GNUNET_malloc (sizeof (struct GSC_Client) + msize);
  c->client_handle = client;
  c->tcnt = msize / sizeof (uint16_t);
  c->options = ntohl (im->options);
  all_client_options |= c->options;
  c->types = (const uint16_t *) &c[1];
  c->connectmap = GNUNET_CONTAINER_multipeermap_create (16, GNUNET_NO);
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_put (c->connectmap,
                                                    &GSC_my_identity,
                                                    NULL,
                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  wtypes = (uint16_t *) & c[1];
  for (i = 0; i < c->tcnt; i++)
    wtypes[i] = ntohs (types[i]);
  GSC_TYPEMAP_add (wtypes, c->tcnt);
  GNUNET_CONTAINER_DLL_insert (client_head, client_tail, c);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Client connecting to core service is interested in %u message types\n",
              (unsigned int) c->tcnt);
  /* send init reply message */
  irm.header.size = htons (sizeof (struct InitReplyMessage));
  irm.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_INIT_REPLY);
  irm.reserved = htonl (0);
  irm.my_identity = GSC_my_identity;
  send_to_client (c, &irm.header, GNUNET_NO);
  GSC_SESSIONS_notify_client_about_sessions (c);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Handle #GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST message.
 *
 * @param cls unused
 * @param client new client that sent a #GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST
 * @param message the `struct SendMessageRequest` (presumably)
 */
static void
handle_client_send_request (void *cls,
                            struct GNUNET_SERVER_Client *client,
                            const struct GNUNET_MessageHeader *message)
{
  const struct SendMessageRequest *req;
  struct GSC_Client *c;
  struct GSC_ClientActiveRequest *car;
  int is_loopback;

  req = (const struct SendMessageRequest *) message;
  c = find_client (client);
  if (NULL == c)
  {
    /* client did not send INIT first! */
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client,
                                GNUNET_SYSERR);
    return;
  }
  if (NULL == c->requests)
    c->requests = GNUNET_CONTAINER_multipeermap_create (16,
                                                        GNUNET_NO);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Client asked for transmission to `%s'\n",
              GNUNET_i2s (&req->peer));
  is_loopback =
      (0 ==
       memcmp (&req->peer,
               &GSC_my_identity,
               sizeof (struct GNUNET_PeerIdentity)));
  if ((! is_loopback) &&
      (GNUNET_YES !=
       GNUNET_CONTAINER_multipeermap_contains (c->connectmap,
                                               &req->peer)))
  {
    /* neighbour must have disconnected since request was issued,
     * ignore (client will realize it once it processes the
     * disconnect notification) */
    GNUNET_STATISTICS_update (GSC_stats,
                              gettext_noop
                              ("# send requests dropped (disconnected)"), 1,
                              GNUNET_NO);
    GNUNET_SERVER_receive_done (client,
                                GNUNET_OK);
    return;
  }

  car = GNUNET_CONTAINER_multipeermap_get (c->requests,
                                           &req->peer);
  if (NULL == car)
  {
    /* create new entry */
    car = GNUNET_new (struct GSC_ClientActiveRequest);
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_CONTAINER_multipeermap_put (c->requests,
                                                      &req->peer,
                                                      car,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
    car->client_handle = c;
  }
  else
  {
    /* dequeue and recycle memory from pending request, there can only
       be at most one per client and peer */
    GSC_SESSIONS_dequeue_request (car);
  }
  car->target = req->peer;
  car->received_time = GNUNET_TIME_absolute_get ();
  car->deadline = GNUNET_TIME_absolute_ntoh (req->deadline);
  car->priority = (enum GNUNET_CORE_Priority) ntohl (req->priority);
  car->msize = ntohs (req->size);
  car->smr_id = req->smr_id;
  car->was_solicited = GNUNET_NO;
  if (is_loopback)
  {
    /* loopback, satisfy immediately */
    GSC_CLIENTS_solicit_request (car);
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
  GSC_SESSIONS_queue_request (car);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Closure for the #client_tokenizer_callback().
 */
struct TokenizerContext
{

  /**
   * Active request handle for the message.
   */
  struct GSC_ClientActiveRequest *car;

  /**
   * How important is this message.
   */
  enum GNUNET_CORE_Priority priority;

  /**
   * Is corking allowed (set only once we have the real message).
   */
  int cork;

};


/**
 * Handle #GNUNET_MESSAGE_TYPE_CORE_SEND request.
 *
 * @param cls unused
 * @param client the client issuing the request
 * @param message the `struct SendMessage`
 */
static void
handle_client_send (void *cls,
                    struct GNUNET_SERVER_Client *client,
                    const struct GNUNET_MessageHeader *message)
{
  const struct SendMessage *sm;
  struct GSC_Client *c;
  struct TokenizerContext tc;
  uint16_t msize;
  struct GNUNET_TIME_Relative delay;
  struct GNUNET_TIME_Relative overdue;

  msize = ntohs (message->size);
  if (msize < sizeof (struct SendMessage))
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  sm = (const struct SendMessage *) message;
  msize -= sizeof (struct SendMessage);
  GNUNET_break (0 == ntohl (sm->reserved));
  c = find_client (client);
  if (NULL == c)
  {
    /* client did not send INIT first! */
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  tc.car
    = GNUNET_CONTAINER_multipeermap_get (c->requests,
                                         &sm->peer);
  if (NULL == tc.car)
  {
    /* Must have been that we first approved the request, then got disconnected
     * (which triggered removal of the 'car') and now the client gives us a message
     * just *before* the client learns about the disconnect.  Theoretically, we
     * might also now be *again* connected.  So this can happen (but should be
     * rare).  If it does happen, the message is discarded. */
    GNUNET_STATISTICS_update (GSC_stats,
                              gettext_noop
                              ("# messages discarded (session disconnected)"),
                              1, GNUNET_NO);
    GNUNET_SERVER_receive_done (client,
                                GNUNET_OK);
    return;
  }
  delay = GNUNET_TIME_absolute_get_duration (tc.car->received_time);
  overdue = GNUNET_TIME_absolute_get_duration (tc.car->deadline);
  tc.cork = ntohl (sm->cork);
  tc.priority = (enum GNUNET_CORE_Priority) ntohl (sm->priority);
  if (overdue.rel_value_us > GNUNET_CONSTANTS_LATENCY_WARN.rel_value_us)
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Client waited %s for transmission of %u bytes to `%s'%s\n",
                GNUNET_STRINGS_relative_time_to_string (delay,
                                                        GNUNET_YES),
                msize,
                GNUNET_i2s (&sm->peer),
                tc.cork ? "" : " (corked)");
  else
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Client waited %s for transmission of %u bytes to `%s'%s\n",
                GNUNET_STRINGS_relative_time_to_string (delay,
                                                        GNUNET_YES),
                msize,
                GNUNET_i2s (&sm->peer),
                tc.cork ? "" : " (corked)");

  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_remove (c->requests,
                                                       &sm->peer,
                                                       tc.car));
  GNUNET_SERVER_mst_receive (client_mst, &tc,
                             (const char *) &sm[1],
                             msize,
                             GNUNET_YES,
                             GNUNET_NO);
  GSC_SESSIONS_dequeue_request (tc.car);
  GNUNET_free (tc.car);
  GNUNET_SERVER_receive_done (client,
                              GNUNET_OK);
}


/**
 * Functions with this signature are called whenever a complete
 * message is received by the tokenizer.  Used by the 'client_mst' for
 * dispatching messages from clients to either the SESSION subsystem
 * or other CLIENT (for loopback).
 *
 * @param cls closure
 * @param client reservation request (`struct GSC_ClientActiveRequest`)
 * @param message the actual message
 */
static int
client_tokenizer_callback (void *cls,
                           void *client,
                           const struct GNUNET_MessageHeader *message)
{
  struct TokenizerContext *tc = client;
  struct GSC_ClientActiveRequest *car = tc->car;
  char buf[92];

  GNUNET_snprintf (buf, sizeof (buf),
		   gettext_noop ("# bytes of messages of type %u received"),
		   (unsigned int) ntohs (message->type));
  GNUNET_STATISTICS_update (GSC_stats,
                            buf,
                            ntohs (message->size),
                            GNUNET_NO);
  if (0 ==
      memcmp (&car->target,
              &GSC_my_identity,
              sizeof (struct GNUNET_PeerIdentity)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Delivering message of type %u to myself\n",
                ntohs (message->type));
    GSC_CLIENTS_deliver_message (&GSC_my_identity, message,
				 ntohs (message->size),
				 GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND);
    GSC_CLIENTS_deliver_message (&GSC_my_identity, message,
				 sizeof (struct GNUNET_MessageHeader),
				 GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND);
    GSC_CLIENTS_deliver_message (&GSC_my_identity, message,
				 ntohs (message->size),
				 GNUNET_CORE_OPTION_SEND_FULL_INBOUND);
    GSC_CLIENTS_deliver_message (&GSC_my_identity, message,
				 sizeof (struct GNUNET_MessageHeader),
				 GNUNET_CORE_OPTION_SEND_HDR_INBOUND);
  }
  else
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Delivering message of type %u and size %u to %s\n",
                ntohs (message->type), ntohs (message->size),
                GNUNET_i2s (&car->target));
    GSC_CLIENTS_deliver_message (&car->target, message,
				 ntohs (message->size),
				 GNUNET_CORE_OPTION_SEND_FULL_OUTBOUND);
    GSC_CLIENTS_deliver_message (&car->target, message,
				 sizeof (struct GNUNET_MessageHeader),
				 GNUNET_CORE_OPTION_SEND_HDR_OUTBOUND);
    GSC_SESSIONS_transmit (car,
                           message,
                           tc->cork,
                           tc->priority);
  }
  return GNUNET_OK;
}


/**
 * Free client request records.
 *
 * @param cls NULL
 * @param key identity of peer for which this is an active request
 * @param value the `struct GSC_ClientActiveRequest` to free
 * @return #GNUNET_YES (continue iteration)
 */
static int
destroy_active_client_request (void *cls,
			       const struct GNUNET_PeerIdentity *key,
                               void *value)
{
  struct GSC_ClientActiveRequest *car = value;

  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_remove (car->
                                                       client_handle->requests,
                                                       &car->target,
                                                       car));
  GSC_SESSIONS_dequeue_request (car);
  GNUNET_free (car);
  return GNUNET_YES;
}


/**
 * A client disconnected, clean up.
 *
 * @param cls closure
 * @param client identification of the client
 */
static void
handle_client_disconnect (void *cls,
                          struct GNUNET_SERVER_Client *client)
{
  struct GSC_Client *c;

  if (NULL == client)
    return;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Client %p has disconnected from core service.\n",
              client);
  c = find_client (client);
  if (c == NULL)
    return;                     /* client never sent INIT */
  GNUNET_CONTAINER_DLL_remove (client_head, client_tail, c);
  if (c->requests != NULL)
  {
    GNUNET_CONTAINER_multipeermap_iterate (c->requests,
                                           &destroy_active_client_request,
                                           NULL);
    GNUNET_CONTAINER_multipeermap_destroy (c->requests);
  }
  GNUNET_CONTAINER_multipeermap_destroy (c->connectmap);
  c->connectmap = NULL;
  GSC_TYPEMAP_remove (c->types, c->tcnt);
  GNUNET_free (c);

  /* recalculate 'all_client_options' */
  all_client_options = 0;
  for (c = client_head; NULL != c ; c = c->next)
    all_client_options |= c->options;
}


/**
 * Tell a client that we are ready to receive the message.
 *
 * @param car request that is now ready; the responsibility
 *        for the handle remains shared between CLIENTS
 *        and SESSIONS after this call.
 */
void
GSC_CLIENTS_solicit_request (struct GSC_ClientActiveRequest *car)
{
  struct GSC_Client *c;
  struct SendMessageReady smr;
  struct GNUNET_TIME_Relative delay;
  struct GNUNET_TIME_Relative left;

  c = car->client_handle;
  if (GNUNET_YES !=
      GNUNET_CONTAINER_multipeermap_contains (c->connectmap,
                                              &car->target))
  {
    /* connection has gone down since, drop request */
    GNUNET_assert (0 !=
                   memcmp (&car->target,
                           &GSC_my_identity,
                           sizeof (struct GNUNET_PeerIdentity)));
    GSC_SESSIONS_dequeue_request (car);
    GSC_CLIENTS_reject_request (car,
                                GNUNET_NO);
    return;
  }
  delay = GNUNET_TIME_absolute_get_duration (car->received_time);
  left = GNUNET_TIME_absolute_get_duration (car->deadline);
  if (left.rel_value_us > GNUNET_CONSTANTS_LATENCY_WARN.rel_value_us)
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Client waited %s for permission to transmit to `%s'%s (priority %u)\n",
                GNUNET_STRINGS_relative_time_to_string (delay,
                                                        GNUNET_YES),
                GNUNET_i2s (&car->target),
                (0 == left.rel_value_us)
                ? " (past deadline)"
                : "",
                car->priority);
  smr.header.size = htons (sizeof (struct SendMessageReady));
  smr.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_SEND_READY);
  smr.size = htons (car->msize);
  smr.smr_id = car->smr_id;
  smr.peer = car->target;
  send_to_client (c, &smr.header, GNUNET_NO);
}


/**
 * We will never be ready to transmit the given message in (disconnect
 * or invalid request).  Frees resources associated with @a car.  We
 * don't explicitly tell the client, he'll learn with the disconnect
 * (or violated the protocol).
 *
 * @param car request that now permanently failed; the
 *        responsibility for the handle is now returned
 *        to CLIENTS (SESSIONS is done with it).
 * @param drop_client #GNUNET_YES if the client violated the protocol
 *        and we should thus drop the connection
 */
void
GSC_CLIENTS_reject_request (struct GSC_ClientActiveRequest *car,
                            int drop_client)
{
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_remove (car->
                                                       client_handle->requests,
                                                       &car->target,
                                                       car));
  if (GNUNET_YES == drop_client)
    GNUNET_SERVER_client_disconnect (car->client_handle->client_handle);
  GNUNET_free (car);
}


/**
 * Notify a particular client about a change to existing connection to
 * one of our neighbours (check if the client is interested).  Called
 * from 'GSC_SESSIONS_notify_client_about_sessions'.
 *
 * @param client client to notify
 * @param neighbour identity of the neighbour that changed status
 * @param tmap_old previous type map for the neighbour, NULL for connect
 * @param tmap_new updated type map for the neighbour, NULL for disconnect
 */
void
GSC_CLIENTS_notify_client_about_neighbour (struct GSC_Client *client,
                                           const struct GNUNET_PeerIdentity *neighbour,
                                           const struct GSC_TypeMap *tmap_old,
                                           const struct GSC_TypeMap *tmap_new)
{
  struct ConnectNotifyMessage *cnm;
  size_t size;
  char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE - 1] GNUNET_ALIGN;
  struct DisconnectNotifyMessage dcm;
  int old_match;
  int new_match;

  old_match = GSC_TYPEMAP_test_match (tmap_old, client->types, client->tcnt);
  new_match = GSC_TYPEMAP_test_match (tmap_new, client->types, client->tcnt);
  if (old_match == new_match)
  {
    GNUNET_assert (old_match ==
                   GNUNET_CONTAINER_multipeermap_contains (client->connectmap,
                                                           neighbour));
    return;                     /* no change */
  }
  if (old_match == GNUNET_NO)
  {
    /* send connect */
    GNUNET_assert (GNUNET_NO ==
                   GNUNET_CONTAINER_multipeermap_contains (client->connectmap,
                                                           neighbour));
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multipeermap_put (client->connectmap,
                                                      neighbour,
                                                      NULL,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
    size = sizeof (struct ConnectNotifyMessage);
    cnm = (struct ConnectNotifyMessage *) buf;
    cnm->header.size = htons (size);
    cnm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT);
    cnm->reserved = htonl (0);
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Sending `%s' message to client.\n",
                "NOTIFY_CONNECT");
    cnm->peer = *neighbour;
    send_to_client (client, &cnm->header, GNUNET_NO);
  }
  else
  {
    /* send disconnect */
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multipeermap_contains (client->connectmap,
                                                           neighbour));
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multipeermap_remove (client->connectmap,
                                                         neighbour,
                                                         NULL));
    dcm.header.size = htons (sizeof (struct DisconnectNotifyMessage));
    dcm.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_DISCONNECT);
    dcm.reserved = htonl (0);
    dcm.peer = *neighbour;
    send_to_client (client, &dcm.header, GNUNET_NO);
  }
}


/**
 * Notify all clients about a change to existing session.
 * Called from SESSIONS whenever there is a change in sessions
 * or types processed by the respective peer.
 *
 * @param neighbour identity of the neighbour that changed status
 * @param tmap_old previous type map for the neighbour, NULL for connect
 * @param tmap_new updated type map for the neighbour, NULL for disconnect
 */
void
GSC_CLIENTS_notify_clients_about_neighbour (const struct GNUNET_PeerIdentity *neighbour,
                                            const struct GSC_TypeMap *tmap_old,
                                            const struct GSC_TypeMap *tmap_new)
{
  struct GSC_Client *c;

  for (c = client_head; NULL != c; c = c->next)
    GSC_CLIENTS_notify_client_about_neighbour (c, neighbour,
                                               tmap_old, tmap_new);
}


/**
 * Deliver P2P message to interested clients.  Caller must have checked
 * that the sending peer actually lists the given message type as one
 * of its types.
 *
 * @param sender peer who sent us the message
 * @param msg the message
 * @param msize number of bytes to transmit
 * @param options options for checking which clients should
 *        receive the message
 */
void
GSC_CLIENTS_deliver_message (const struct GNUNET_PeerIdentity *sender,
                             const struct GNUNET_MessageHeader *msg,
                             uint16_t msize,
                             uint32_t options)
{
  size_t size = msize + sizeof (struct NotifyTrafficMessage);
  char buf[size] GNUNET_ALIGN;
  struct NotifyTrafficMessage *ntm;

  if (size >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
  {
    GNUNET_break (0);
    /* recovery strategy: throw performance data away... */
    size = msize + sizeof (struct NotifyTrafficMessage);
  }
  if (! ( (0 != (all_client_options & options)) ||
	  (0 != (options & GNUNET_CORE_OPTION_SEND_FULL_INBOUND)) ))
    return; /* no client cares about this message notification */
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core service passes message from `%4s' of type %u to client.\n",
              GNUNET_i2s (sender),
              (unsigned int) ntohs (msg->type));
  GSC_SESSIONS_add_to_typemap (sender, ntohs (msg->type));
  ntm = (struct NotifyTrafficMessage *) buf;
  ntm->header.size = htons (size);
  if (0 != (options & (GNUNET_CORE_OPTION_SEND_FULL_INBOUND | GNUNET_CORE_OPTION_SEND_HDR_INBOUND)))
    ntm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_INBOUND);
  else
    ntm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_OUTBOUND);
  ntm->peer = *sender;
  memcpy (&ntm[1],
          msg,
          msize);
  send_to_all_clients (sender,
                       &ntm->header,
                       GNUNET_YES,
                       options,
                       ntohs (msg->type));
}


/**
 * Initialize clients subsystem.
 *
 * @param server handle to server clients connect to
 */
void
GSC_CLIENTS_init (struct GNUNET_SERVER_Handle *server)
{
  static const struct GNUNET_SERVER_MessageHandler handlers[] = {
    {&handle_client_init, NULL,
     GNUNET_MESSAGE_TYPE_CORE_INIT, 0},
    {&GSC_KX_handle_client_monitor_peers, NULL,
     GNUNET_MESSAGE_TYPE_CORE_MONITOR_PEERS,
     sizeof (struct GNUNET_MessageHeader)},
    {&handle_client_send_request, NULL,
     GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST,
     sizeof (struct SendMessageRequest)},
    {&handle_client_send, NULL,
     GNUNET_MESSAGE_TYPE_CORE_SEND, 0},
    {NULL, NULL, 0, 0}
  };

  /* setup notification */
  client_mst = GNUNET_SERVER_mst_create (&client_tokenizer_callback, NULL);
  notifier =
      GNUNET_SERVER_notification_context_create (server, MAX_NOTIFY_QUEUE);
  GNUNET_SERVER_disconnect_notify (server,
                                   &handle_client_disconnect, NULL);
  GNUNET_SERVER_add_handlers (server, handlers);
}


/**
 * Shutdown clients subsystem.
 */
void
GSC_CLIENTS_done ()
{
  struct GSC_Client *c;

  while (NULL != (c = client_head))
    handle_client_disconnect (NULL, c->client_handle);
  if (NULL != notifier)
  {
    GNUNET_SERVER_notification_context_destroy (notifier);
    notifier = NULL;
  }
  if (NULL != client_mst)
  {
    GNUNET_SERVER_mst_destroy (client_mst);
    client_mst = NULL;
  }
}

/* end of gnunet-service-core_clients.c */