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- /*
- This file is part of GNUnet.
- Copyright (C) 2009-2019 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
- */
- /**
- * @author Christian Grothoff
- *
- * @file
- * API of the transport service towards the communicator processes.
- *
- * @defgroup transport TRANSPORT service
- * Low-level communication with other peers
- *
- * @see [Documentation](https://gnunet.org/transport-service)
- *
- * @{
- */
- #ifndef GNUNET_TRANSPORT_COMMUNICATION_SERVICE_H
- #define GNUNET_TRANSPORT_COMMUNICATION_SERVICE_H
- #ifdef __cplusplus
- extern "C" {
- #if 0 /* keep Emacsens' auto-indent happy */
- }
- #endif
- #endif
- #include "gnunet_util_lib.h"
- #include "gnunet_nt_lib.h"
- /**
- * Version number of the transport communication API.
- */
- #define GNUNET_TRANSPORT_COMMUNICATION_VERSION 0x00000000
- /**
- * Function called by the transport service to initialize a
- * message queue given address information about another peer.
- * If and when the communication channel is established, the
- * communicator must call #GNUNET_TRANSPORT_communicator_mq_add()
- * to notify the service that the channel is now up. It is
- * the responsibility of the communicator to manage sane
- * retries and timeouts for any @a peer/@a address combination
- * provided by the transport service. Timeouts and retries
- * do not need to be signalled to the transport service.
- *
- * @param cls closure
- * @param peer identity of the other peer
- * @param address where to send the message, human-readable
- * communicator-specific format, 0-terminated, UTF-8
- * @return #GNUNET_OK on success, #GNUNET_SYSERR if the provided address is
- * invalid
- */
- typedef int (*GNUNET_TRANSPORT_CommunicatorMqInit) (
- void *cls,
- const struct GNUNET_PeerIdentity *peer,
- const char *address);
- /**
- * Opaque handle to the transport service for communicators.
- */
- struct GNUNET_TRANSPORT_CommunicatorHandle;
- /**
- * What characteristics does this communicator have?
- *
- * FIXME: may want to distinguish bi-directional as well,
- * should we define a bit for that? Needed in DV logic (handle_dv_learn)!
- */
- enum GNUNET_TRANSPORT_CommunicatorCharacteristics
- {
- /**
- * Characteristics are unknown (i.e. DV).
- */
- GNUNET_TRANSPORT_CC_UNKNOWN = 0,
- /**
- * Transmission is reliabile (with ACKs), i.e. TCP/HTTP/HTTPS.
- */
- GNUNET_TRANSPORT_CC_RELIABLE = 1,
- /**
- * Transmission is unreliable (i.e. UDP)
- */
- GNUNET_TRANSPORT_CC_UNRELIABLE = 2
- };
- /**
- * Function called when the transport service has received a
- * backchannel message for this communicator (!) via a different
- * return path.
- *
- * Typically used to receive messages of type
- * #GNUNET_MESSAGE_TYPE_TRANSPORT_COMMUNICATOR_FC_LIMITS or
- * #GNUNET_MESSAGE_TYPE_TRANSPORT_COMMUNICATOR_KX_CONFIRMATION
- * as well as communicator-specific messages to assist with
- * NAT traversal.
- *
- * @param cls closure
- * @param sender which peer sent the notification
- * @param msg payload
- */
- typedef void (*GNUNET_TRANSPORT_CommunicatorNotify) (
- void *cls,
- const struct GNUNET_PeerIdentity *sender,
- const struct GNUNET_MessageHeader *msg);
- /**
- * Connect to the transport service.
- *
- * @param cfg configuration to use
- * @param config_section section of the configuration to use for options
- * @param addr_prefix address prefix for addresses supported by this
- * communicator, could be NULL for incoming-only communicators
- * @param cc what characteristics does the communicator have?
- * @param mq_init function to call to initialize a message queue given
- * the address of another peer, can be NULL if the
- * communicator only supports receiving messages
- * @param mq_init_cls closure for @a mq_init
- * @param notify_cb function to pass backchannel messages to communicator
- * @param notify_cb_cls closure for @a notify_cb
- * @return NULL on error
- */
- struct GNUNET_TRANSPORT_CommunicatorHandle *
- GNUNET_TRANSPORT_communicator_connect (
- const struct GNUNET_CONFIGURATION_Handle *cfg,
- const char *config_section_name,
- const char *addr_prefix,
- enum GNUNET_TRANSPORT_CommunicatorCharacteristics cc,
- GNUNET_TRANSPORT_CommunicatorMqInit mq_init,
- void *mq_init_cls,
- GNUNET_TRANSPORT_CommunicatorNotify notify_cb,
- void *notify_cb_cls);
- /**
- * Disconnect from the transport service.
- *
- * @param ch handle returned from connect
- */
- void
- GNUNET_TRANSPORT_communicator_disconnect (
- struct GNUNET_TRANSPORT_CommunicatorHandle *ch);
- /* ************************* Receiving *************************** */
- /**
- * Function called to notify communicator that we have received
- * and processed the message. Used for flow control (if supported
- * by the communicator).
- *
- * @param cls closure
- * @param success #GNUNET_SYSERR on failure (try to disconnect/reset connection)
- * #GNUNET_OK on success
- */
- typedef void (*GNUNET_TRANSPORT_MessageCompletedCallback) (void *cls,
- int success);
- /**
- * Notify transport service that the communicator has received
- * a message.
- *
- * @param handle connection to transport service
- * @param sender presumed sender of the message (details to be checked
- * by higher layers)
- * @param msg the message
- * @param expected_addr_validity how long does the communicator believe it
- * will continue to be able to receive messages from the same address
- * on which it received this message?
- * @param cb function to call once handling the message is done, NULL if
- * flow control is not supported by this communicator
- * @param cb_cls closure for @a cb
- * @return #GNUNET_OK if all is well, #GNUNET_NO if the message was
- * immediately dropped due to memory limitations (communicator
- * should try to apply back pressure),
- * #GNUNET_SYSERR if the message could not be delivered because
- * the tranport service is not yet up
- */
- int
- GNUNET_TRANSPORT_communicator_receive (
- struct GNUNET_TRANSPORT_CommunicatorHandle *handle,
- const struct GNUNET_PeerIdentity *sender,
- const struct GNUNET_MessageHeader *msg,
- struct GNUNET_TIME_Relative expected_addr_validity,
- GNUNET_TRANSPORT_MessageCompletedCallback cb,
- void *cb_cls);
- /* ************************* Discovery *************************** */
- /**
- * Handle returned to identify the internal data structure the transport
- * API has created to manage a message queue to a particular peer.
- */
- struct GNUNET_TRANSPORT_QueueHandle;
- /**
- * Possible states of a connection.
- */
- enum GNUNET_TRANSPORT_ConnectionStatus
- {
- /**
- * Connection is down.
- */
- GNUNET_TRANSPORT_CS_DOWN = -1,
- /**
- * this is an outbound connection (transport initiated)
- */
- GNUNET_TRANSPORT_CS_OUTBOUND = 0,
- /**
- * this is an inbound connection (communicator initiated)
- */
- GNUNET_TRANSPORT_CS_INBOUND = 1
- };
- /**
- * Notify transport service that a MQ became available due to an
- * "inbound" connection or because the communicator discovered the
- * presence of another peer.
- *
- * @param ch connection to transport service
- * @param peer peer with which we can now communicate
- * @param address address in human-readable format, 0-terminated, UTF-8
- * @param mtu maximum message size supported by queue, 0 if
- * sending is not supported, SIZE_MAX for no MTU
- * @param nt which network type does the @a address belong to?
- * @param cs what is the connection status of the queue?
- * @param mq message queue of the @a peer
- * @return API handle identifying the new MQ
- */
- struct GNUNET_TRANSPORT_QueueHandle *
- GNUNET_TRANSPORT_communicator_mq_add (
- struct GNUNET_TRANSPORT_CommunicatorHandle *ch,
- const struct GNUNET_PeerIdentity *peer,
- const char *address,
- uint32_t mtu,
- enum GNUNET_NetworkType nt,
- enum GNUNET_TRANSPORT_ConnectionStatus cs,
- struct GNUNET_MQ_Handle *mq);
- /**
- * Notify transport service that an MQ became unavailable due to a
- * disconnect or timeout.
- *
- * @param qh handle for the queue that must be invalidated
- */
- void
- GNUNET_TRANSPORT_communicator_mq_del (struct GNUNET_TRANSPORT_QueueHandle *qh);
- /**
- * Internal representation of an address a communicator is
- * currently providing for the transport service.
- */
- struct GNUNET_TRANSPORT_AddressIdentifier;
- /**
- * Notify transport service about an address that this communicator
- * provides for this peer.
- *
- * @param ch connection to transport service
- * @param address our address in human-readable format, 0-terminated, UTF-8
- * @param nt which network type does the address belong to?
- * @param expiration when does the communicator forsee this address expiring?
- */
- struct GNUNET_TRANSPORT_AddressIdentifier *
- GNUNET_TRANSPORT_communicator_address_add (
- struct GNUNET_TRANSPORT_CommunicatorHandle *ch,
- const char *address,
- enum GNUNET_NetworkType nt,
- struct GNUNET_TIME_Relative expiration);
- /**
- * Notify transport service about an address that this communicator
- * no longer provides for this peer.
- *
- * @param ai address that is no longer provided
- */
- void
- GNUNET_TRANSPORT_communicator_address_remove (
- struct GNUNET_TRANSPORT_AddressIdentifier *ai);
- /**
- * The communicator asks the transport service to route a message via
- * a different path to another communicator service at another peer.
- * This must only be done for special control traffic (as there is no
- * flow control for this API), such as acknowledgements, and generally
- * only be done if the communicator is uni-directional (i.e. cannot
- * send the message back itself).
- *
- * While backchannel messages are signed and encrypted, communicators
- * must protect against replay attacks when using this backchannel
- * communication!
- *
- * @param ch handle of this communicator
- * @param pid peer to send the message to
- * @param comm name of the communicator to send the message to
- * @param header header of the message to transmit and pass via the
- * notify-API to @a pid's communicator @a comm
- */
- void
- GNUNET_TRANSPORT_communicator_notify (
- struct GNUNET_TRANSPORT_CommunicatorHandle *ch,
- const struct GNUNET_PeerIdentity *pid,
- const char *comm,
- const struct GNUNET_MessageHeader *header);
- #if 0 /* keep Emacsens' auto-indent happy */
- {
- #endif
- #ifdef __cplusplus
- }
- #endif
- /* ifndef GNUNET_TRANSPORT_COMMUNICATOR_SERVICE_H */
- #endif
- /** @} */ /* end of group */
- /* end of gnunet_transport_communicator_service.h */
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