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/*
     This file is part of GNUnet.
     (C) 2009, 2010 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., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file include/gnunet_core_service.h
 * @brief core service; this is the main API for encrypted P2P
 *        communications
 * @author Christian Grothoff
 */

#ifndef GNUNET_CORE_SERVICE_H
#define GNUNET_CORE_SERVICE_H

#ifdef __cplusplus
extern "C"
{
#if 0                           /* keep Emacsens' auto-indent happy */
}
#endif
#endif

#include "gnunet_util_lib.h"
#include "gnunet_transport_service.h"

/**
 * Version number of GNUnet-core API.
 */
#define GNUNET_CORE_VERSION 0x00000000


/**
 * Opaque handle to the service.
 */
struct GNUNET_CORE_Handle;


/**
 * Method called whenever a given peer connects.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 * @param atsi performance data for the connection
 */
typedef void (*GNUNET_CORE_ConnectEventHandler) (void *cls,
                                                 const struct
                                                 GNUNET_PeerIdentity * peer,
                                                 const struct
                                                 GNUNET_TRANSPORT_ATS_Information
                                                 * atsi);


/**
 * Method called whenever a given peer has a status change.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 * @param timeout absolute time when this peer will time out
 *        unless we see some further activity from it
 * @param bandwidth_in available amount of inbound bandwidth
 * @param bandwidth_out available amount of outbound bandwidth
 * @param atsi performance data for the connection
 */
typedef void (*GNUNET_CORE_PeerStatusEventHandler) (void *cls,
                                                    const struct
                                                    GNUNET_PeerIdentity * peer,
                                                    struct
                                                    GNUNET_BANDWIDTH_Value32NBO
                                                    bandwidth_in,
                                                    struct
                                                    GNUNET_BANDWIDTH_Value32NBO
                                                    bandwidth_out,
                                                    struct GNUNET_TIME_Absolute
                                                    timeout,
                                                    const struct
                                                    GNUNET_TRANSPORT_ATS_Information
                                                    * atsi);


/**
 * Method called whenever a peer disconnects.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 */
typedef void (*GNUNET_CORE_DisconnectEventHandler) (void *cls,
                                                    const struct
                                                    GNUNET_PeerIdentity * peer);


/**
 * Functions with this signature are called whenever a message is
 * received or transmitted.
 *
 * @param cls closure (set from GNUNET_CORE_connect)
 * @param peer the other peer involved (sender or receiver, NULL
 *        for loopback messages where we are both sender and receiver)
 * @param message the actual message
 * @param atsi performance data for the connection
 * @return GNUNET_OK to keep the connection open,
 *         GNUNET_SYSERR to close it (signal serious error)
 */
typedef int (*GNUNET_CORE_MessageCallback) (void *cls,
                                            const struct GNUNET_PeerIdentity *
                                            other,
                                            const struct GNUNET_MessageHeader *
                                            message,
                                            const struct
                                            GNUNET_TRANSPORT_ATS_Information *
                                            atsi);


/**
 * Message handler.  Each struct specifies how to handle on particular
 * type of message received.
 */
struct GNUNET_CORE_MessageHandler
{
  /**
   * Function to call for messages of "type".
   */
  GNUNET_CORE_MessageCallback callback;

  /**
   * Type of the message this handler covers.
   */
  uint16_t type;

  /**
   * Expected size of messages of this type.  Use 0 for variable-size.
   * If non-zero, messages of the given type will be discarded if they
   * do not have the right size.
   */
  uint16_t expected_size;

};


/**
 * Function called after GNUNET_CORE_connect has succeeded (or failed
 * for good).  Note that the private key of the peer is intentionally
 * not exposed here; if you need it, your process should try to read
 * the private key file directly (which should work if you are
 * authorized...).
 *
 * @param cls closure
 * @param server handle to the server, NULL if we failed
 * @param my_identity ID of this peer, NULL if we failed
 */
typedef void (*GNUNET_CORE_StartupCallback) (void *cls,
                                             struct GNUNET_CORE_Handle * server,
                                             const struct GNUNET_PeerIdentity *my_identity);


/**
 * Connect to the core service.  Note that the connection may complete
 * (or fail) asynchronously.  This function primarily causes the given
 * callback notification functions to be invoked whenever the
 * specified event happens.  The maximum number of queued
 * notifications (queue length) is per client but the queue is shared
 * across all types of notifications.  So a slow client that registers
 * for 'outbound_notify' also risks missing 'inbound_notify' messages.
 * Certain events (such as connect/disconnect notifications) are not
 * subject to queue size limitations.
 *
 * @param cfg configuration to use
 * @param queue_size size of the per-peer message queue
 * @param cls closure for the various callbacks that follow (including handlers in the handlers array)
 * @param init callback to call on timeout or once we have successfully
 *        connected to the core service; note that timeout is only meaningful if init is not NULL
 * @param connects function to call on peer connect, can be NULL
 * @param disconnects function to call on peer disconnect / timeout, can be NULL
 * @param status_events function to call on peer status changes, can be NULL
 * @param inbound_notify function to call for all inbound messages, can be NULL
 *                note that the core is allowed to drop notifications about inbound
 *                messages if the client does not process them fast enough (for this
 *                notification type, a bounded queue is used)
 * @param inbound_hdr_only set to GNUNET_YES if inbound_notify will only read the
 *                GNUNET_MessageHeader and hence we do not need to give it the full message;
 *                can be used to improve efficiency, ignored if inbound_notify is NULL
 *                note that the core is allowed to drop notifications about inbound
 *                messages if the client does not process them fast enough (for this
 *                notification type, a bounded queue is used)
 * @param outbound_notify function to call for all outbound messages, can be NULL;
 *                note that the core is allowed to drop notifications about outbound
 *                messages if the client does not process them fast enough (for this
 *                notification type, a bounded queue is used)
 * @param outbound_hdr_only set to GNUNET_YES if outbound_notify will only read the
 *                GNUNET_MessageHeader and hence we do not need to give it the full message
 *                can be used to improve efficiency, ignored if outbound_notify is NULL
 *                note that the core is allowed to drop notifications about outbound
 *                messages if the client does not process them fast enough (for this
 *                notification type, a bounded queue is used)
 * @param handlers callbacks for messages we care about, NULL-terminated
 *                note that the core is allowed to drop notifications about inbound
 *                messages if the client does not process them fast enough (for this
 *                notification type, a bounded queue is used)
 * @return handle to the core service (only useful for disconnect until 'init' is called),
 *           NULL on error (in this case, init is never called)
 */
struct GNUNET_CORE_Handle *
GNUNET_CORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
                     unsigned int queue_size, void *cls,
                     GNUNET_CORE_StartupCallback init,
                     GNUNET_CORE_ConnectEventHandler connects,
                     GNUNET_CORE_DisconnectEventHandler disconnects,
                     GNUNET_CORE_PeerStatusEventHandler status_events,
                     GNUNET_CORE_MessageCallback inbound_notify,
                     int inbound_hdr_only,
                     GNUNET_CORE_MessageCallback outbound_notify,
                     int outbound_hdr_only,
                     const struct GNUNET_CORE_MessageHandler *handlers);


/**
 * Disconnect from the core service.    This function can only
 * be called *after* all pending 'GNUNET_CORE_notify_transmit_ready'
 * requests have been explicitly cancelled.
 *
 * @param handle connection to core to disconnect
 */
void
GNUNET_CORE_disconnect (struct GNUNET_CORE_Handle *handle);


/**
 * Function called with perference change information about the given peer.
 *
 * @param cls closure
 * @param peer identifies the peer
 * @param amount set to the amount that was actually reserved or unreserved;
 *               either the full requested amount or zero (no partial reservations)
 * @param res_delay if the reservation could not be satisfied (amount was 0), how
 *        long should the client wait until re-trying?
 */
typedef void (*GNUNET_CORE_PeerConfigurationInfoCallback) (void *cls,
                                                           const struct
                                                           GNUNET_PeerIdentity *
                                                           peer,
                                                           int32_t amount,
                                                           struct
                                                           GNUNET_TIME_Relative
                                                           res_delay);



/**
 * Context that can be used to cancel a peer information request.
 */
struct GNUNET_CORE_InformationRequestContext;


/**
 * Obtain statistics and/or change preferences for the given peer.
 * You can only have one such pending request per peer.
 *
 * @param h core handle
 * @param peer identifies the peer
 * @param amount reserve N bytes for receiving, negative
 *                amounts can be used to undo a (recent) reservation;
 * @param preference increase incoming traffic share preference by this amount;
 *                in the absence of "amount" reservations, we use this
 *                preference value to assign proportional bandwidth shares
 *                to all connected peers
 * @param info function to call with the resulting configuration information
 * @param info_cls closure for info
 * @return NULL on error
 */
struct GNUNET_CORE_InformationRequestContext *
GNUNET_CORE_peer_change_preference (struct GNUNET_CORE_Handle *h,
                                    const struct GNUNET_PeerIdentity *peer,
                                    int32_t amount, uint64_t preference,
                                    GNUNET_CORE_PeerConfigurationInfoCallback
                                    info, void *info_cls);


/**
 * Cancel request for getting information about a peer.
 * Note that an eventual change in preference, trust or bandwidth
 * assignment MAY have already been committed at the time,
 * so cancelling a request is NOT sure to undo the original
 * request.  The original request may or may not still commit.
 * The only thing cancellation ensures is that the callback
 * from the original request will no longer be called.
 *
 * @param irc context returned by the original GNUNET_CORE_peer_get_info call
 */
void
GNUNET_CORE_peer_change_preference_cancel (struct
                                           GNUNET_CORE_InformationRequestContext
                                           *irc);


/**
 * Iterate over all connected peers.
 *
 * @param cfg configuration handle
 * @param peer_cb function to call with the peer information
 * @param cb_cls closure for peer_cb
 * @return GNUNET_OK on success, GNUNET_SYSERR on errors
 */
int
GNUNET_CORE_iterate_peers (const struct GNUNET_CONFIGURATION_Handle *cfg,
                           GNUNET_CORE_ConnectEventHandler peer_cb,
                           void *cb_cls);

/**
 * Iterate over all currently connected peers.
 * Calls peer_cb with each connected peer, and then
 * once with NULL to indicate that all peers have
 * been handled.
 *
 * @param cfg configuration to use
 * @param peer the specific peer to check for
 * @param peer_cb function to call with the peer information
 * @param cb_cls closure for peer_cb
 *
 * @return GNUNET_OK if iterating, GNUNET_SYSERR on error
 */
int
GNUNET_CORE_is_peer_connected (const struct GNUNET_CONFIGURATION_Handle *cfg,
                               struct GNUNET_PeerIdentity *peer,
                               GNUNET_CORE_ConnectEventHandler peer_cb,
                               void *cb_cls);


/**
 * Handle for a transmission request.
 */
struct GNUNET_CORE_TransmitHandle;


/**
 * Ask the core to call "notify" once it is ready to transmit the
 * given number of bytes to the specified "target".   Must only be
 * called after a connection to the respective peer has been
 * established (and the client has been informed about this).
 *
 *
 * @param handle connection to core service
 * @param cork is corking allowed for this transmission?
 * @param priority how important is the message?
 * @param maxdelay how long can the message wait?
 * @param target who should receive the message,
 *        use NULL for this peer (loopback)
 * @param notify_size how many bytes of buffer space does notify want?
 * @param notify function to call when buffer space is available;
 *        will be called with NULL on timeout or if the overall queue
 *        for this peer is larger than queue_size and this is currently
 *        the message with the lowest priority; will also be called
 *        with 'NULL' buf if the peer disconnects; since the disconnect
 *        signal will be emmitted even later, clients MUST cancel
 *        all pending transmission requests DURING the disconnect
 *        handler (unless they ensure that 'notify' never calls
 *        'GNUNET_CORE_notify_transmit_ready').
 * @param notify_cls closure for notify
 * @return non-NULL if the notify callback was queued,
 *         NULL if we can not even queue the request (insufficient
 *         memory); if NULL is returned, "notify" will NOT be called.
 */
struct GNUNET_CORE_TransmitHandle *
GNUNET_CORE_notify_transmit_ready (struct GNUNET_CORE_Handle *handle, int cork,
                                   uint32_t priority,
                                   struct GNUNET_TIME_Relative maxdelay,
                                   const struct GNUNET_PeerIdentity *target,
                                   size_t notify_size,
                                   GNUNET_CONNECTION_TransmitReadyNotify notify,
                                   void *notify_cls);


/**
 * Cancel the specified transmission-ready notification.
 *
 * @param th handle that was returned by "notify_transmit_ready".
 */
void
GNUNET_CORE_notify_transmit_ready_cancel (struct GNUNET_CORE_TransmitHandle
                                          *th);


#if 0                           /* keep Emacsens' auto-indent happy */
{
#endif
#ifdef __cplusplus
}
#endif

/* ifndef GNUNET_CORE_SERVICE_H */
#endif
/* end of gnunet_core_service.h */