gnunet-android

gnunet_set_service.h (16189B)

---

 /*
       This file is part of GNUnet
       Copyright (C) 2013, 2014 GNUnet e.V.
 
       GNUnet is free software: you can redistribute it and/or modify it
       under the terms of the GNU Affero General Public License as published
       by the Free Software Foundation, either version 3 of the License,
       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
       Affero General Public License for more details.
 
       You should have received a copy of the GNU Affero General Public License
       along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
      SPDX-License-Identifier: AGPL3.0-or-later
  */
 
 /**
  * @addtogroup Sets
  * @{
  *
  * @author Florian Dold
  * @author Christian Grothoff
  *
  * @file
  * Two-peer set operations
  *
  * @defgroup set  Set service
  * Two-peer set operations
  *
  * @see [Documentation](https://gnunet.org/set-subsystem)
  *
  * @{
  */
 
 #ifndef GNUNET_SET_SERVICE_H
 #define GNUNET_SET_SERVICE_H
 
 #ifdef __cplusplus
 extern "C"
 {
 #if 0                           /* keep Emacsens' auto-indent happy */
 }
 #endif
 #endif
 
 
 #include "gnunet_common.h"
 #include "gnunet_time_lib.h"
 #include "gnunet_configuration_lib.h"
 
 
 /**
  * Maximum size of a context message for set operation requests.
  */
 #define GNUNET_SET_CONTEXT_MESSAGE_MAX_SIZE ((1 << 16) - 1024)
 
 
 /**
  * Opaque handle to a set.
  */
 struct GNUNET_SET_Handle;
 
 /**
  * Opaque handle to a set operation request from another peer.
  */
 struct GNUNET_SET_Request;
 
 /**
  * Opaque handle to a listen operation.
  */
 struct GNUNET_SET_ListenHandle;
 
 /**
  * Opaque handle to a set operation.
  */
 struct GNUNET_SET_OperationHandle;
 
 
 /**
  * The operation that a set set supports.
  */
 enum GNUNET_SET_OperationType
 {
   /**
    * A purely local set that does not support any operation.
    */
   GNUNET_SET_OPERATION_NONE,
 
   /**
    * Set intersection, only return elements that are in both sets.
    */
   GNUNET_SET_OPERATION_INTERSECTION,
 
   /**
    * Set union, return all elements that are in at least one of the sets.
    */
   GNUNET_SET_OPERATION_UNION
 };
 
 
 /**
  * Status for the result callback
  */
 enum GNUNET_SET_Status
 {
   /**
    * Everything went ok, we are transmitting an element of the
    * result (in set, or to be removed from set, depending on
    * the `enum GNUNET_SET_ResultMode`).
    *
    * Only applies to
    * #GNUNET_SET_RESULT_FULL,
    * #GNUNET_SET_RESULT_ADDED,
    * #GNUNET_SET_RESULT_REMOVED,
    */
   GNUNET_SET_STATUS_OK,
 
   /**
    * Element should be added to the result set
    * of the local peer, i.e. the local peer is
    * missing an element.
    *
    * Only applies to #GNUNET_SET_RESULT_SYMMETRIC
    */
   GNUNET_SET_STATUS_ADD_LOCAL,
 
   /**
    * Element should be added to the result set
    * of the remote peer, i.e. the remote peer is
    * missing an element.
    *
    * Only applies to #GNUNET_SET_RESULT_SYMMETRIC
    */
   GNUNET_SET_STATUS_ADD_REMOTE,
 
   /**
    * The other peer refused to to the operation with us,
    * or something went wrong.
    */
   GNUNET_SET_STATUS_FAILURE,
 
   /**
    * Success, all elements have been returned (but the other peer
    * might still be receiving some from us, so we are not done).  Only
    * used during UNION operation.
    */
   GNUNET_SET_STATUS_HALF_DONE,
 
   /**
    * Success, all elements have been sent (and received).
    */
   GNUNET_SET_STATUS_DONE
 };
 
 
 /**
  * The way results are given to the client.
  */
 enum GNUNET_SET_ResultMode
 {
   /**
    * Client gets every element in the resulting set.
    *
    * Only supported for set intersection.
    */
   GNUNET_SET_RESULT_FULL,
 
   /**
    * Client gets notified of the required changes
    * for both the local and the remote set.
    *
    * Only supported for set
    */
   GNUNET_SET_RESULT_SYMMETRIC,
 
   /**
    * Client gets only elements that have been removed from the set.
    *
    * Only supported for set intersection.
    */
   GNUNET_SET_RESULT_REMOVED,
 
   /**
    * Client gets only elements that have been added to the set.
    *
    * Only supported for set union.
    */
   GNUNET_SET_RESULT_ADDED
 };
 
 
 /**
  * Element stored in a set.
  */
 struct GNUNET_SET_Element
 {
   /**
    * Number of bytes in the buffer pointed to by data.
    */
   uint16_t size;
 
   /**
    * Application-specific element type.
    */
   uint16_t element_type;
 
   /**
    * Actual data of the element
    */
   const void *data;
 };
 
 
 /**
  * Possible options to pass to a set operation.
  *
  * Used as tag for struct #GNUNET_SET_Option.
  */
 enum GNUNET_SET_OptionType
 {
   /**
    * List terminator.
    */
   GNUNET_SET_OPTION_END=0,
   /**
    * Fail set operations when the other peer shows weird behavior
    * that might by a Byzantine fault.
    *
    * For set union, 'v.num' is a lower bound on elements
    * that the other peer must have in common with us.
    */
   GNUNET_SET_OPTION_BYZANTINE=1,
   /**
    * Do not use the optimized set operation, but send full sets.
    * Might trigger Byzantine fault detection.
    */
   GNUNET_SET_OPTION_FORCE_FULL=2,
   /**
    * Only use optimized set operations, even though for this
    * particular set operation they might be much slower.
    * Might trigger Byzantine fault detection.
    */
   GNUNET_SET_OPTION_FORCE_DELTA=4,
 };
 
 
 /**
  * Option for set operations.
  */
 struct GNUNET_SET_Option
 {
   /**
    * Type of the option.
    */
   enum GNUNET_SET_OptionType type;
 
   /**
    * Value for the option, only used with some options.
    */
   union
   {
     uint64_t num;
   } v;
 };
 
 
 /**
  * Continuation used for some of the set operations
  *
  * @param cls closure
  */
 typedef void
 (*GNUNET_SET_Continuation) (void *cls);
 
 
 /**
  * Callback for set operation results. Called for each element
  * in the result set.
  *
  * @param cls closure
  * @param element a result element, only valid if status is #GNUNET_SET_STATUS_OK
  * @param current_size current set size
  * @param status see `enum GNUNET_SET_Status`
  */
 typedef void
 (*GNUNET_SET_ResultIterator) (void *cls,
                               const struct GNUNET_SET_Element *element,
                               uint64_t current_size,
                               enum GNUNET_SET_Status status);
 
 /**
  * Iterator for set elements.
  *
  * @param cls closure
  * @param element the current element, NULL if all elements have been
  *        iterated over
  * @return #GNUNET_YES to continue iterating, #GNUNET_NO to stop.
  */
 typedef int
 (*GNUNET_SET_ElementIterator) (void *cls,
                                const struct GNUNET_SET_Element *element);
 
 
 /**
  * Called when another peer wants to do a set operation with the
  * local peer. If a listen error occurs, the @a request is NULL.
  *
  * @param cls closure
  * @param other_peer the other peer
  * @param context_msg message with application specific information from
  *        the other peer
  * @param request request from the other peer (never NULL), use GNUNET_SET_accept()
  *        to accept it, otherwise the request will be refused
  *        Note that we can't just return value from the listen callback,
  *        as it is also necessary to specify the set we want to do the
  *        operation with, with sometimes can be derived from the context
  *        message. It's necessary to specify the timeout.
  */
 typedef void
 (*GNUNET_SET_ListenCallback) (void *cls,
                               const struct GNUNET_PeerIdentity *other_peer,
                               const struct GNUNET_MessageHeader *context_msg,
                               struct GNUNET_SET_Request *request);
 
 
 typedef void
 (*GNUNET_SET_CopyReadyCallback) (void *cls,
                                  struct GNUNET_SET_Handle *copy);
 
 
 /**
  * Create an empty set, supporting the specified operation.
  *
  * @param cfg configuration to use for connecting to the
  *        set service
  * @param op operation supported by the set
  *        Note that the operation has to be specified
  *        beforehand, as certain set operations need to maintain
  *        data structures specific to the operation
  * @return a handle to the set
  */
 struct GNUNET_SET_Handle *
 GNUNET_SET_create (const struct GNUNET_CONFIGURATION_Handle *cfg,
                    enum GNUNET_SET_OperationType op);
 
 
 /**
  * Add an element to the given set.
  * After the element has been added (in the sense of being
  * transmitted to the set service), @a cont will be called.
  * Calls to #GNUNET_SET_add_element can be queued
  *
  * @param set set to add element to
  * @param element element to add to the set
  * @param cont continuation called after the element has been added
  * @param cont_cls closure for @a cont
  * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
  *         set is invalid (e.g. the set service crashed)
  */
 int
 GNUNET_SET_add_element (struct GNUNET_SET_Handle *set,
                         const struct GNUNET_SET_Element *element,
                         GNUNET_SET_Continuation cont,
                         void *cont_cls);
 
 
 /**
  * Remove an element to the given set. 
  * After the element has been removed (in the sense of the request 
  * being transmitted to the set service), @a cont will be called.  
  * Multiple calls to GNUNET_SET_remove_element() can be queued
  *
  * @param set set to remove element from
  * @param element element to remove from the set
  * @param cont continuation called after the element has been removed
  * @param cont_cls closure for @a cont
  * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
  *         set is invalid (e.g. the set service crashed)
  */
 int
 GNUNET_SET_remove_element (struct GNUNET_SET_Handle *set,
                            const struct GNUNET_SET_Element *element,
                            GNUNET_SET_Continuation cont,
                            void *cont_cls);
 
 
 void
 GNUNET_SET_copy_lazy (struct GNUNET_SET_Handle *set,
                       GNUNET_SET_CopyReadyCallback cb,
                       void *cls);
 
 
 /**
  * Destroy the set handle, and free all associated resources.
  * Iterations must have completed (or be explicitly canceled)
  * before destroying the corresponding set.  Operations may
  * still be pending when a set is destroyed.
  *
  * @param set set to destroy
  */
 void
 GNUNET_SET_destroy (struct GNUNET_SET_Handle *set);
 
 
 /**
  * Prepare a set operation to be evaluated with another peer.
  * The evaluation will not start until the client provides
  * a local set with GNUNET_SET_commit().
  *
  * @param other_peer peer with the other set
  * @param app_id hash for the application using the set
  * @param context_msg additional information for the request
  * @param result_mode specified how results will be returned,
  *        see `enum GNUNET_SET_ResultMode`.
  * @param result_cb called on error or success
  * @param result_cls closure for @a result_cb
  * @return a handle to cancel the operation
  */
 struct GNUNET_SET_OperationHandle *
 GNUNET_SET_prepare (const struct GNUNET_PeerIdentity *other_peer,
                     const struct GNUNET_HashCode *app_id,
                     const struct GNUNET_MessageHeader *context_msg,
                     enum GNUNET_SET_ResultMode result_mode,
                     struct GNUNET_SET_Option options[],
                     GNUNET_SET_ResultIterator result_cb,
                     void *result_cls);
 
 
 /**
  * Wait for set operation requests for the given application ID.
  * If the connection to the set service is lost, the listener is
  * re-created transparently with exponential backoff.
  *
  * @param cfg configuration to use for connecting to
  *            the set service
  * @param operation operation we want to listen for
  * @param app_id id of the application that handles set operation requests
  * @param listen_cb called for each incoming request matching the operation
  *                  and application id
  * @param listen_cls handle for @a listen_cb
  * @return a handle that can be used to cancel the listen operation
  */
 struct GNUNET_SET_ListenHandle *
 GNUNET_SET_listen (const struct GNUNET_CONFIGURATION_Handle *cfg,
                    enum GNUNET_SET_OperationType op_type,
                    const struct GNUNET_HashCode *app_id,
                    GNUNET_SET_ListenCallback listen_cb,
                    void *listen_cls);
 
 
 /**
  * Cancel the given listen operation.  After calling cancel, the
  * listen callback for this listen handle will not be called again.
  * Note that cancelling a listen operation will automatically reject
  * all operations that have not yet been accepted.
  *
  * @param lh handle for the listen operation
  */
 void
 GNUNET_SET_listen_cancel (struct GNUNET_SET_ListenHandle *lh);
 
 
 /**
  * Accept a request we got via GNUNET_SET_listen().  Must be called during
  * GNUNET_SET_listen(), as the `struct GNUNET_SET_Request` becomes invalid
  * afterwards.
  * Call GNUNET_SET_commit() to provide the local set to use for the operation,
  * and to begin the exchange with the remote peer.
  *
  * @param request request to accept
  * @param result_mode specified how results will be returned,
  *        see `enum GNUNET_SET_ResultMode`.
  * @param result_cb callback for the results
  * @param result_cls closure for @a result_cb
  * @return a handle to cancel the operation
  */
 struct GNUNET_SET_OperationHandle *
 GNUNET_SET_accept (struct GNUNET_SET_Request *request,
                    enum GNUNET_SET_ResultMode result_mode,
                    struct GNUNET_SET_Option options[],
                    GNUNET_SET_ResultIterator result_cb,
                    void *result_cls);
 
 
 /**
  * Commit a set to be used with a set operation.
  * This function is called once we have fully constructed
  * the set that we want to use for the operation.  At this
  * time, the P2P protocol can then begin to exchange the
  * set information and call the result callback with the
  * result information.
  *
  * @param oh handle to the set operation
  * @param set the set to use for the operation
  * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
  *         set is invalid (e.g. the set service crashed)
  */
 int
 GNUNET_SET_commit (struct GNUNET_SET_OperationHandle *oh,
                    struct GNUNET_SET_Handle *set);
 
 
 /**
  * Cancel the given set operation.  May not be called after the
  * operation's `GNUNET_SET_ResultIterator` has been called with a
  * status that indicates error, timeout or done.
  *
  * @param oh set operation to cancel
  */
 void
 GNUNET_SET_operation_cancel (struct GNUNET_SET_OperationHandle *oh);
 
 
 /**
  * Iterate over all elements in the given set.
  * Note that this operation involves transferring every element of the set
  * from the service to the client, and is thus costly.
  * Only one iteration per set may be active at the same time.
  *
  * @param set the set to iterate over
  * @param iter the iterator to call for each element
  * @param iter_cls closure for @a iter
  * @return #GNUNET_YES if the iteration started successfully,
  *         #GNUNET_NO if another iteration was still active,
  *         #GNUNET_SYSERR if the set is invalid (e.g. the server crashed, disconnected)
  */
 int
 GNUNET_SET_iterate (struct GNUNET_SET_Handle *set,
                     GNUNET_SET_ElementIterator iter,
                     void *iter_cls);
 
 
 /**
  * Stop iteration over all elements in the given set.  Can only
  * be called before the iteration has "naturally" completed its
  * turn.
  *
  * @param set the set to stop iterating over
  */
 void
 GNUNET_SET_iterate_cancel (struct GNUNET_SET_Handle *set);
 
 
 /**
  * Create a copy of an element.  The copy
  * must be GNUNET_free-d by the caller.
  *
  * @param element the element to copy
  * @return the copied element
  */
 struct GNUNET_SET_Element *
 GNUNET_SET_element_dup (const struct GNUNET_SET_Element *element);
 
 
 /**
  * Hash a set element.
  *
  * @param element the element that should be hashed
  * @param[out] ret_hash a pointer to where the hash of @a element
  *        should be stored
  */
 void
 GNUNET_SET_element_hash (const struct GNUNET_SET_Element *element,
                          struct GNUNET_HashCode *ret_hash);
 
 
 #if 0                           /* keep Emacsens' auto-indent happy */
 {
 #endif
 #ifdef __cplusplus
 }
 #endif
 
 #endif
 
 /** @} */  /* end of group */
 
 /** @} */ /* end of group addition */