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3 (C) 2009-2013 Christian Grothoff (and other contributing authors)
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22 * @file include/gnunet_server_lib.h
23 * @brief library for building GNUnet network servers
24 * @author Christian Grothoff
25 * @defgroup server functions for a server that communicates with clients
29 #ifndef GNUNET_SERVER_LIB_H
30 #define GNUNET_SERVER_LIB_H
35 #if 0 /* keep Emacsens' auto-indent happy */
40 #include "gnunet_common.h"
41 #include "gnunet_connection_lib.h"
45 * Largest supported message (to be precise, one byte more
46 * than the largest possible message, so tests involving
47 * this value should check for messages being smaller than
50 #define GNUNET_SERVER_MAX_MESSAGE_SIZE 65536
53 * Smallest supported message.
55 #define GNUNET_SERVER_MIN_BUFFER_SIZE sizeof (struct GNUNET_MessageHeader)
58 * @brief handle for a server
60 struct GNUNET_SERVER_Handle;
63 * @brief opaque handle for a client of the server
65 struct GNUNET_SERVER_Client;
68 * @brief opaque handle server returns for aborting transmission to a client.
70 struct GNUNET_SERVER_TransmitHandle;
74 * Functions with this signature are called whenever a message is
78 * @param client identification of the client
79 * @param message the actual message
81 typedef void (*GNUNET_SERVER_MessageCallback) (void *cls,
82 struct GNUNET_SERVER_Client *client,
83 const struct GNUNET_MessageHeader
88 * Message handler. Each struct specifies how to handle on particular
89 * type of message received.
91 struct GNUNET_SERVER_MessageHandler
94 * Function to call for messages of "type".
96 GNUNET_SERVER_MessageCallback callback;
99 * Closure argument for "callback".
104 * Type of the message this handler covers.
109 * Expected size of messages of this type. Use 0 for
110 * variable-size. If non-zero, messages of the given
111 * type will be discarded (and the connection closed)
112 * if they do not have the right size.
114 uint16_t expected_size;
120 * Create a new server.
122 * @param access function for access control
123 * @param access_cls closure for @a access
124 * @param lsocks NULL-terminated array of listen sockets
125 * @param idle_timeout after how long should we timeout idle connections?
126 * @param require_found if #GNUNET_YES, connections sending messages of unknown type
128 * @return handle for the new server, NULL on error
129 * (typically, "port" already in use)
131 struct GNUNET_SERVER_Handle *
132 GNUNET_SERVER_create_with_sockets (GNUNET_CONNECTION_AccessCheck access,
134 struct GNUNET_NETWORK_Handle **lsocks,
135 struct GNUNET_TIME_Relative idle_timeout,
139 * Create a new server.
141 * @param access function for access control
142 * @param access_cls closure for @a access
143 * @param server_addr address toes listen on (including port), NULL terminated array
144 * @param socklen lengths of respective @a server_addr
145 * @param idle_timeout after how long should we timeout idle connections?
146 * @param require_found if #GNUNET_YES, connections sending messages of unknown type
148 * @return handle for the new server, NULL on error
149 * (typically, "port" already in use)
151 struct GNUNET_SERVER_Handle *
152 GNUNET_SERVER_create (GNUNET_CONNECTION_AccessCheck access, void *access_cls,
153 struct sockaddr *const *server_addr,
154 const socklen_t * socklen,
155 struct GNUNET_TIME_Relative idle_timeout,
160 * Suspend accepting connections from the listen socket temporarily.
161 * Resume activity using #GNUNET_SERVER_resume.
163 * @param server server to stop accepting connections.
166 GNUNET_SERVER_suspend (struct GNUNET_SERVER_Handle *server);
170 * Resume accepting connections from the listen socket.
172 * @param server server to resume accepting connections.
175 GNUNET_SERVER_resume (struct GNUNET_SERVER_Handle *server);
179 * Stop the listen socket and get ready to shutdown the server once
180 * only clients marked using #GNUNET_SERVER_client_mark_monitor are
183 * @param server server to stop listening on
186 GNUNET_SERVER_stop_listening (struct GNUNET_SERVER_Handle *server);
190 * Free resources held by this server.
192 * @param server server to destroy
195 GNUNET_SERVER_destroy (struct GNUNET_SERVER_Handle *server);
199 * Add additional handlers to an existing server.
201 * @param server the server to add handlers to
202 * @param handlers array of message handlers for
203 * incoming messages; the last entry must
204 * have "NULL" for the "callback"; multiple
205 * entries for the same type are allowed,
206 * they will be called in order of occurence.
207 * These handlers can be removed later;
208 * the handlers array must exist until removed
209 * (or server is destroyed).
212 GNUNET_SERVER_add_handlers (struct GNUNET_SERVER_Handle *server,
213 const struct GNUNET_SERVER_MessageHandler
218 * Notify us when the server has enough space to transmit
219 * a message of the given size to the given client.
221 * @param client client to transmit message to
222 * @param size requested amount of buffer space
223 * @param timeout after how long should we give up (and call
224 * notify with buf NULL and size 0)?
225 * @param callback function to call when space is available
226 * @param callback_cls closure for @a callback
227 * @return non-NULL if the notify callback was queued; can be used
228 * to cancel the request using
229 * #GNUNET_SERVER_notify_transmit_ready_cancel.
230 * NULL if we are already going to notify someone else (busy)
232 struct GNUNET_SERVER_TransmitHandle *
233 GNUNET_SERVER_notify_transmit_ready (struct GNUNET_SERVER_Client *client,
235 struct GNUNET_TIME_Relative timeout,
236 GNUNET_CONNECTION_TransmitReadyNotify
237 callback, void *callback_cls);
241 * Abort transmission request.
243 * @param th request to abort
246 GNUNET_SERVER_notify_transmit_ready_cancel (struct GNUNET_SERVER_TransmitHandle *th);
250 * Set the 'monitor' flag on this client. Clients which have been
251 * marked as 'monitors' won't prevent the server from shutting down
252 * once #GNUNET_SERVER_stop_listening has been invoked. The idea is
253 * that for "normal" clients we likely want to allow them to process
254 * their requests; however, monitor-clients are likely to 'never'
255 * disconnect during shutdown and thus will not be considered when
256 * determining if the server should continue to exist after
257 * #GNUNET_SERVER_destroy has been called.
259 * @param client the client to set the 'monitor' flag on
262 GNUNET_SERVER_client_mark_monitor (struct GNUNET_SERVER_Client *client);
266 * Set the persistent flag on this client, used to setup client
267 * connection to only be killed when the process of the service it's
268 * connected to is actually dead. This API is used during shutdown
269 * signalling within ARM, and it is not expected that typical users
270 * of the API would need this function.
272 * @param client the client to set the persistent flag on
275 GNUNET_SERVER_client_persist_ (struct GNUNET_SERVER_Client *client);
279 * Resume receiving from this client, we are done processing the
280 * current request. This function must be called from within each
281 * #GNUNET_SERVER_MessageCallback (or its respective continuations).
283 * @param client client we were processing a message of
284 * @param success #GNUNET_OK to keep the connection open and
285 * continue to receive
286 * #GNUNET_NO to close the connection (normal behavior)
287 * #GNUNET_SYSERR to close the connection (signal
291 GNUNET_SERVER_receive_done (struct GNUNET_SERVER_Client *client,
296 * Change the timeout for a particular client. Decreasing the timeout
297 * may not go into effect immediately (only after the previous timeout
298 * times out or activity happens on the socket).
300 * @param client the client to update
301 * @param timeout new timeout for activities on the socket
304 GNUNET_SERVER_client_set_timeout (struct GNUNET_SERVER_Client *client,
305 struct GNUNET_TIME_Relative timeout);
309 * Return user context associated with the given client.
310 * Note: you should probably use the macro (call without the underscore).
312 * @param client client to query
313 * @param size number of bytes in user context struct (for verification only)
314 * @return pointer to user context
317 GNUNET_SERVER_client_get_user_context_ (struct GNUNET_SERVER_Client *client,
322 * Set user context to be associated with the given client.
323 * Note: you should probably use the macro (call without the underscore).
325 * @param client client to query
326 * @param ptr pointer to user context
327 * @param size number of bytes in user context struct (for verification only)
330 GNUNET_SERVER_client_set_user_context_ (struct GNUNET_SERVER_Client *client,
336 * Return user context associated with the given client.
338 * @param client client to query
339 * @param type expected return type (i.e. 'struct Foo')
340 * @return pointer to user context of type 'type *'.
342 #define GNUNET_SERVER_client_get_user_context(client,type) \
343 (type *) GNUNET_SERVER_client_get_user_context_ (client, sizeof (type))
346 * Set user context to be associated with the given client.
348 * @param client client to query
349 * @param value pointer to user context
351 #define GNUNET_SERVER_client_set_user_context(client,value) \
352 GNUNET_SERVER_client_set_user_context_ (client, value, sizeof (*value))
356 * Disable the warning the server issues if a message is not acknowledged
357 * in a timely fashion. Use this call if a client is intentionally delayed
358 * for a while. Only applies to the current message.
360 * @param client client for which to disable the warning
363 GNUNET_SERVER_disable_receive_done_warning (struct GNUNET_SERVER_Client
368 * Inject a message into the server, pretend it came
369 * from the specified client. Delivery of the message
370 * will happen instantly (if a handler is installed;
371 * otherwise the call does nothing).
373 * @param server the server receiving the message
374 * @param sender the "pretended" sender of the message
376 * @param message message to transmit
377 * @return #GNUNET_OK if the message was OK and the
378 * connection can stay open
379 * #GNUNET_SYSERR if the connection to the
380 * client should be shut down
383 GNUNET_SERVER_inject (struct GNUNET_SERVER_Handle *server,
384 struct GNUNET_SERVER_Client *sender,
385 const struct GNUNET_MessageHeader *message);
389 * Add a TCP socket-based connection to the set of handles managed by
390 * this server. Use this function for outgoing (P2P) connections that
391 * we initiated (and where this server should process incoming
394 * @param server the server to use
395 * @param connection the connection to manage (client must
396 * stop using this connection from now on)
397 * @return the client handle (client should call
398 * #GNUNET_SERVER_client_drop on the return value eventually)
400 struct GNUNET_SERVER_Client *
401 GNUNET_SERVER_connect_socket (struct GNUNET_SERVER_Handle *server,
402 struct GNUNET_CONNECTION_Handle *connection);
406 * Notify the server that the given client handle should
407 * be kept (keeps the connection up if possible, increments
408 * the internal reference counter).
410 * @param client the client to keep
413 GNUNET_SERVER_client_keep (struct GNUNET_SERVER_Client *client);
417 * Notify the server that the given client handle is no
418 * longer required. Decrements the reference counter. If
419 * that counter reaches zero an inactive connection maybe
422 * @param client the client to drop
425 GNUNET_SERVER_client_drop (struct GNUNET_SERVER_Client *client);
429 * Obtain the network address of the other party.
431 * @param client the client to get the address for
432 * @param addr where to store the address
433 * @param addrlen where to store the length of @a addr
434 * @return #GNUNET_OK on success
437 GNUNET_SERVER_client_get_address (struct GNUNET_SERVER_Client *client,
438 void **addr, size_t *addrlen);
442 * Functions with this signature are called whenever a client
443 * is disconnected on the network level.
446 * @param client identification of the client; NULL
447 * for the last call when the server is destroyed
449 typedef void (*GNUNET_SERVER_DisconnectCallback) (void *cls,
450 struct GNUNET_SERVER_Client *client);
454 * Functions with this signature are called whenever a client
455 * is connected on the network level.
458 * @param client identification of the client
460 typedef void (*GNUNET_SERVER_ConnectCallback) (void *cls,
461 struct GNUNET_SERVER_Client *client);
465 * Ask the server to notify us whenever a client disconnects.
466 * This function is called whenever the actual network connection
467 * is closed; the reference count may be zero or larger than zero
468 * at this point. If the server is destroyed before this
469 * notification is explicitly cancelled, the 'callback' will
470 * once be called with a 'client' argument of NULL to indicate
471 * that the server itself is now gone (and that the callback
472 * won't be called anymore and also can no longer be cancelled).
474 * @param server the server manageing the clients
475 * @param callback function to call on disconnect
476 * @param callback_cls closure for @a callback
479 GNUNET_SERVER_disconnect_notify (struct GNUNET_SERVER_Handle *server,
480 GNUNET_SERVER_DisconnectCallback callback,
485 * Ask the server to notify us whenever a client connects.
486 * This function is called whenever the actual network connection
487 * is opened. If the server is destroyed before this
488 * notification is explicitly cancelled, the @a callback will
489 * once be called with a 'client' argument of NULL to indicate
490 * that the server itself is now gone (and that the callback
491 * won't be called anymore and also can no longer be cancelled).
493 * @param server the server manageing the clients
494 * @param callback function to call on sconnect
495 * @param callback_cls closure for @a callback
498 GNUNET_SERVER_connect_notify (struct GNUNET_SERVER_Handle *server,
499 GNUNET_SERVER_ConnectCallback callback,
504 * Ask the server to stop notifying us whenever a client disconnects.
505 * Arguments must match exactly those given to
506 * #GNUNET_SERVER_disconnect_notify. It is not necessary to call this
507 * function during shutdown of the server; in fact, most applications
508 * will never use this function.
510 * @param server the server manageing the clients
511 * @param callback function to call on disconnect
512 * @param callback_cls closure for @a callback
515 GNUNET_SERVER_disconnect_notify_cancel (struct GNUNET_SERVER_Handle *server,
516 GNUNET_SERVER_DisconnectCallback
517 callback, void *callback_cls);
521 * Ask the server to stop notifying us whenever a client connects.
522 * Arguments must match exactly those given to
523 * #GNUNET_SERVER_connect_notify. It is not necessary to call this
524 * function during shutdown of the server; in fact, most applications
525 * will never use this function.
527 * @param server the server manageing the clients
528 * @param callback function to call on connect
529 * @param callback_cls closure for @a callback
532 GNUNET_SERVER_connect_notify_cancel (struct GNUNET_SERVER_Handle *server,
533 GNUNET_SERVER_ConnectCallback callback,
538 * Ask the server to disconnect from the given client. This is the
539 * same as passing #GNUNET_SYSERR to #GNUNET_SERVER_receive_done,
540 * except that it allows dropping of a client even when not handling a
541 * message from that client.
543 * @param client the client to disconnect from
546 GNUNET_SERVER_client_disconnect (struct GNUNET_SERVER_Client *client);
550 * Disable the "CORK" feature for communication with the given client,
551 * forcing the OS to immediately flush the buffer on transmission
552 * instead of potentially buffering multiple messages.
554 * @param client handle to the client
555 * @return #GNUNET_OK on success
558 GNUNET_SERVER_client_disable_corking (struct GNUNET_SERVER_Client *client);
562 * The tansmit context is the key datastructure for a conveniance API
563 * used for transmission of complex results to the client followed
564 * ONLY by signaling receive_done with success or error
566 struct GNUNET_SERVER_TransmitContext;
570 * Create a new transmission context for the given client.
572 * @param client client to create the context for.
573 * @return NULL on error
575 struct GNUNET_SERVER_TransmitContext *
576 GNUNET_SERVER_transmit_context_create (struct GNUNET_SERVER_Client *client);
580 * Append a message to the transmission context.
581 * All messages in the context will be sent by
582 * the #GNUNET_SERVER_transmit_context_run method.
584 * @param tc context to use
585 * @param data what to append to the result message
586 * @param length length of @a data
587 * @param type type of the message
590 GNUNET_SERVER_transmit_context_append_data (struct GNUNET_SERVER_TransmitContext
591 *tc, const void *data,
592 size_t length, uint16_t type);
596 * Append a message to the transmission context.
597 * All messages in the context will be sent by
598 * the transmit_context_run method.
600 * @param tc context to use
601 * @param msg message to append
604 GNUNET_SERVER_transmit_context_append_message (struct
605 GNUNET_SERVER_TransmitContext
607 const struct GNUNET_MessageHeader
612 * Execute a transmission context. If there is an error in the
613 * transmission, the receive_done method will be called with an error
614 * code (#GNUNET_SYSERR), otherwise with #GNUNET_OK.
616 * @param tc transmission context to use
617 * @param timeout when to time out and abort the transmission
620 GNUNET_SERVER_transmit_context_run (struct GNUNET_SERVER_TransmitContext *tc,
621 struct GNUNET_TIME_Relative timeout);
625 * Destroy a transmission context. This function must not be called
626 * after #GNUNET_SERVER_transmit_context_run.
628 * @param tc transmission context to destroy
629 * @param success code to give to #GNUNET_SERVER_receive_done for
630 * the client: #GNUNET_OK to keep the connection open and
631 * continue to receive
632 * #GNUNET_NO to close the connection (normal behavior)
633 * #GNUNET_SYSERR to close the connection (signal
637 GNUNET_SERVER_transmit_context_destroy (struct GNUNET_SERVER_TransmitContext
642 * The notification context is the key datastructure for a conveniance
643 * API used for transmission of notifications to the client until the
644 * client disconnects or is disconnected (or the notification context
645 * is destroyed, in which case we disconnect these clients).
646 * Essentially, all (notification) messages are queued up until the
647 * client is able to read them.
649 struct GNUNET_SERVER_NotificationContext;
653 * Create a new notification context.
655 * @param server server for which this function creates the context
656 * @param queue_length maximum number of messages to keep in
657 * the notification queue; optional messages are dropped
658 * if the queue gets longer than this number of messages
659 * @return handle to the notification context
661 struct GNUNET_SERVER_NotificationContext *
662 GNUNET_SERVER_notification_context_create (struct GNUNET_SERVER_Handle *server,
663 unsigned int queue_length);
667 * Destroy the context, force disconnect for all clients.
669 * @param nc context to destroy.
672 GNUNET_SERVER_notification_context_destroy (struct GNUNET_SERVER_NotificationContext *nc);
676 * Add a client to the notification context.
678 * @param nc context to modify
679 * @param client client to add
682 GNUNET_SERVER_notification_context_add (struct GNUNET_SERVER_NotificationContext *nc,
683 struct GNUNET_SERVER_Client *client);
687 * Send a message to a particular client; must have
688 * already been added to the notification context.
690 * @param nc context to modify
691 * @param client client to transmit to
692 * @param msg message to send
693 * @param can_drop can this message be dropped due to queue length limitations
696 GNUNET_SERVER_notification_context_unicast (struct GNUNET_SERVER_NotificationContext *nc,
697 struct GNUNET_SERVER_Client *client,
698 const struct GNUNET_MessageHeader *msg,
703 * Send a message to all clients of this context.
705 * @param nc context to modify
706 * @param msg message to send
707 * @param can_drop can this message be dropped due to queue length limitations
710 GNUNET_SERVER_notification_context_broadcast (struct GNUNET_SERVER_NotificationContext *nc,
711 const struct GNUNET_MessageHeader *msg,
716 * Handle to a message stream tokenizer.
718 struct GNUNET_SERVER_MessageStreamTokenizer;
722 * Functions with this signature are called whenever a
723 * complete message is received by the tokenizer.
725 * Do not call #GNUNET_SERVER_mst_destroy from within
726 * the scope of this callback.
729 * @param client identification of the client
730 * @param message the actual message
731 * @return #GNUNET_OK on success, #GNUNET_SYSERR to stop further processing
733 typedef int (*GNUNET_SERVER_MessageTokenizerCallback) (void *cls, void *client,
735 GNUNET_MessageHeader *
740 * Create a message stream tokenizer.
742 * @param cb function to call on completed messages
743 * @param cb_cls closure for @a cb
744 * @return handle to tokenizer
746 struct GNUNET_SERVER_MessageStreamTokenizer *
747 GNUNET_SERVER_mst_create (GNUNET_SERVER_MessageTokenizerCallback cb,
752 * Add incoming data to the receive buffer and call the
753 * callback for all complete messages.
755 * @param mst tokenizer to use
756 * @param client_identity ID of client for which this is a buffer,
757 * can be NULL (will be passed back to 'cb')
758 * @param buf input data to add
759 * @param size number of bytes in @a buf
760 * @param purge should any excess bytes in the buffer be discarded
761 * (i.e. for packet-based services like UDP)
762 * @param one_shot only call callback once, keep rest of message in buffer
763 * @return #GNUNET_OK if we are done processing (need more data)
764 * #GNUNET_NO if one_shot was set and we have another message ready
765 * #GNUNET_SYSERR if the data stream is corrupt
768 GNUNET_SERVER_mst_receive (struct GNUNET_SERVER_MessageStreamTokenizer *mst,
769 void *client_identity, const char *buf, size_t size,
770 int purge, int one_shot);
774 * Destroys a tokenizer.
776 * @param mst tokenizer to destroy
779 GNUNET_SERVER_mst_destroy (struct GNUNET_SERVER_MessageStreamTokenizer *mst);
783 * Signature of a function to create a custom tokenizer.
785 * @param cls closure from 'GNUNET_SERVER_set_callbacks'
786 * @param client handle to client the tokenzier will be used for
787 * @return handle to custom tokenizer ('mst')
789 typedef void* (*GNUNET_SERVER_MstCreateCallback) (void *cls,
790 struct GNUNET_SERVER_Client *client);
794 * Signature of a function to destroy a custom tokenizer.
796 * @param cls closure from 'GNUNET_SERVER_set_callbacks'
797 * @param mst custom tokenizer handle
799 typedef void (*GNUNET_SERVER_MstDestroyCallback) (void *cls, void *mst);
803 * Signature of a function to receive data for a custom tokenizer.
805 * @param cls closure from #GNUNET_SERVER_set_callbacks
806 * @param mst custom tokenizer handle
807 * @param client_identity ID of client for which this is a buffer,
808 * can be NULL (will be passed back to 'cb')
809 * @param buf input data to add
810 * @param size number of bytes in @a buf
811 * @param purge should any excess bytes in the buffer be discarded
812 * (i.e. for packet-based services like UDP)
813 * @param one_shot only call callback once, keep rest of message in buffer
814 * @return #GNUNET_OK if we are done processing (need more data)
815 * #GNUNET_NO if one_shot was set and we have another message ready
816 * #GNUNET_SYSERR if the data stream is corrupt
818 typedef int (*GNUNET_SERVER_MstReceiveCallback) (void *cls, void *mst,
819 struct GNUNET_SERVER_Client *client,
820 const char *buf, size_t size,
821 int purge, int one_shot);
825 * Change functions used by the server to tokenize the message stream.
826 * (very rarely used).
828 * @param server server to modify
829 * @param create new tokenizer initialization function
830 * @param destroy new tokenizer destruction function
831 * @param receive new tokenizer receive function
832 * @param cls closure for @a create, @a receive and @a destroy
835 GNUNET_SERVER_set_callbacks (struct GNUNET_SERVER_Handle *server,
836 GNUNET_SERVER_MstCreateCallback create,
837 GNUNET_SERVER_MstDestroyCallback destroy,
838 GNUNET_SERVER_MstReceiveCallback receive,
842 #if 0 /* keep Emacsens' auto-indent happy */
849 /** @} */ /* end of group server */
851 /* ifndef GNUNET_SERVER_LIB_H */
853 /* end of gnunet_server_lib.h */