/*
This file is part of GNUnet.
(C) 2012, 2013 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_psyc_service.h
* @brief PSYC service; high-level access to the PSYC protocol
* note that clients of this API are NOT expected to
* understand the PSYC message format, only the semantics!
* Parsing (and serializing) the PSYC stream format is done
* within the implementation of the libgnunetpsyc library,
* and this API deliberately exposes as little as possible
* of the actual data stream format to the application!
* @author Christian Grothoff
* @author Gabor X Toth
*
* NOTE:
* - this API does not know about psyc's "root" and "places";
* there is no 'root' in GNUnet-Psyc as we're decentralized;
* 'places' and 'persons' are combined within the same
* abstraction, that of a "channel". Channels are identified
* and accessed in this API using a public/private key.
* Higher-level applications should use NAMES within GNS
* to obtain public keys, and the distinction between
* 'places' and 'persons' can then be made with the help
* of the naming system (and/or conventions).
* Channels are (as in PSYC) organized into a hierarchy; each
* channel master (the one with the private key) is then
* the operator of the multicast group (its Origin in
* the terminology of the multicast API).
* - The API supports passing large amounts of data using
* 'streaming' for the argument passed to a method. State
* and variables must fit into memory and cannot be streamed
* (thus, no passing of 4 GB of data in a variable;
* once we implement this, we might want to create a
* @c \#define for the maximum size of a variable).
* - PSYC defines standard variables, methods, etc. This
* library deliberately abstracts over all of these; a
* higher-level API should combine the naming system (GNS)
* and standard methods (message, join, part, warn,
* fail, error) and variables (action, color, time,
* tag, etc.). However, this API does take over the
* routing variables, specifically 'context' (channel),
* and 'source'. We only kind-of support 'target', as
* the target is either everyone in the group or the
* origin, and never just a single member of the group;
* for such individual messages, an application needs to
* construct an 'inbox' channel where the master (only)
* receives messages (but never forwards; private responses
* would be transmitted by joining the senders 'inbox'
* channel -- or a inbox#bob subchannel). The
* goal for all of this is to keep the abstractions in this
* API minimal: interaction with multicast, try \& slice,
* state/variable/channel management. Higher-level
* operations belong elsewhere (so maybe this API should
* be called 'PSYC-low', whereas a higher-level API
* implementing defaults for standard methods and
* variables might be called 'PSYC-std' or 'PSYC-high'.
*/
#ifndef GNUNET_PSYC_SERVICE_H
#define GNUNET_PSYC_SERVICE_H
#ifdef __cplusplus
extern "C"
{
#if 0 /* keep Emacsens' auto-indent happy */
}
#endif
#endif
#include "gnunet_util_lib.h"
#include "gnunet_env_lib.h"
#include "gnunet_multicast_service.h"
/**
* Version number of GNUnet-PSYC API.
*/
#define GNUNET_PSYC_VERSION 0x00000000
/**
* Policy flags for a channel.
*/
enum GNUNET_PSYC_ChannelFlags
{
/**
* Admission must be confirmed by the master.
*/
GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL = 1 << 0,
/**
* Past messages are only available to slaves who were admitted at the time
* they were sent to the channel.
*/
GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY = 1 << 1,
};
/**
* PSYC channel policies.
*/
enum GNUNET_PSYC_Policy
{
/**
* Anyone can join the channel, without announcing his presence;
* all messages are always public and can be distributed freely.
* Joins may be announced, but this is not required.
*/
GNUNET_PSYC_CHANNEL_ANONYMOUS = 0,
/**
* The master must approve membership to the channel, messages must only be
* distributed to current channel slaves. This includes the channel
* state as well as transient messages.
*/
GNUNET_PSYC_CHANNEL_PRIVATE
= GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL
| GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY,
#if IDEAS_FOR_FUTURE
/**
* Anyone can freely join the channel (no approval required);
* however, messages must only be distributed to current channel
* slaves, so the master must still acknowledge that the slave
* joined before transient messages are delivered. As approval is
* guaranteed, the presistent channel state can be synchronized freely
* immediately, prior to master confirmation.
*/
GNUNET_PSYC_CHANNEL_OPEN
= GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY,
/**
* The master must approve joins to the channel, but past messages can be
* freely distributed to slaves.
*/
GNUNET_PSYC_CHANNEL_CLOSED
= GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL,
,
#endif
};
enum GNUNET_PSYC_MessageFlags
{
/**
* First fragment of a message.
*/
GNUNET_PSYC_MESSAGE_FIRST_FRAGMENT = 1 << 0,
/**
* Last fragment of a message.
*/
GNUNET_PSYC_MESSAGE_LAST_FRAGMENT = 1 << 1,
/**
* OR'ed flags if message is not fragmented.
*/
GNUNET_PSYC_MESSAGE_NOT_FRAGMENTED
= GNUNET_PSYC_MESSAGE_FIRST_FRAGMENT
| GNUNET_PSYC_MESSAGE_LAST_FRAGMENT,
/**
* Historic message, retrieved from PSYCstore.
*/
GNUNET_PSYC_MESSAGE_HISTORIC = 1 << 30
};
/**
* M
*/
struct GNUNET_PSYC_MessageMethod
{
/**
* Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD
*/
struct GNUNET_MessageHeader header;
uint32_t reserved GNUNET_PACKED;
/**
* Number of modifiers in the message.
*/
uint32_t mod_count GNUNET_PACKED;
/**
* OR'ed GNUNET_PSYC_MasterTransmitFlags
*/
uint32_t flags GNUNET_PACKED;
/**
* Sending slave's public key.
* NULL if the message is from the master, or when transmitting a message.
*/
struct GNUNET_CRYPTO_EddsaPublicKey slave_key;
/* Followed by NUL-terminated method name. */
};
struct GNUNET_PSYC_MessageModifier
{
/**
* Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER
*/
struct GNUNET_MessageHeader header;
/**
* Size of value.
*/
uint32_t value_size GNUNET_PACKED;
/**
* Size of name, including NUL terminator.
*/
uint16_t name_size GNUNET_PACKED;
/**
* enum GNUNET_ENV_Operator
*/
uint8_t oper;
/* Followed by NUL-terminated name, then the value. */
};
enum GNUNET_PSYC_DataStatus
{
/**
* To be continued.
*/
GNUNET_PSYC_DATA_CONT = 0,
/**
* Reached the end of message.
*/
GNUNET_PSYC_DATA_END = 1,
/**
* Cancelled before the end.
*/
GNUNET_PSYC_DATA_CANCEL = 2
};
struct GNUNET_PSYC_MessageData
{
/**
* Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA
*/
struct GNUNET_MessageHeader header;
/**
* enum GNUNET_PSYC_DataStatus
*/
uint8_t status;
};
/**
* Handle that identifies a join request.
*
* Used to match calls to #GNUNET_PSYC_JoinCallback to the
* corresponding calls to GNUNET_PSYC_join_decision().
*/
struct GNUNET_PSYC_JoinHandle;
/**
* Method called from PSYC upon receiving a message indicating a call to a
* @e method.
*
* @param cls Closure.
* @param slave_key Who transmitted the message.
* - NULL for multicast messages from the master.
* - The sending slave's public key for unicast requests from one of the
* slaves to the master.
* @param message_id Unique message counter for this message.
* Unique only in combination with the given sender for this channel.
* @param method_name Method name from PSYC.
* @param modifier_count Number of elements in the @a modifiers array.
* @param modifiers State modifiers and transient variables for the message.
* @param data_offset Byte offset of @a data in the overall data of the method.
* @param data Data stream given to the method (might not be zero-terminated
* if data is binary).
* @param data_size Number of bytes in @a data.
* @param frag Fragmentation status for the data.
*/
typedef int
(*GNUNET_PSYC_Method) (void *cls,
const struct GNUNET_CRYPTO_EddsaPublicKey *slave_key,
uint64_t message_id,
const char *method_name,
size_t modifier_count,
const struct GNUNET_ENV_Modifier *modifiers,
uint64_t data_offset,
const void *data,
size_t data_size,
enum GNUNET_PSYC_MessageFlags flags);
/**
* Method called from PSYC upon receiving a join request.
*
* @param cls Closure.
* @param slave requesting to join.
* @param method_name Method name in the join request.
* @param variable_count Number of elements in the @a variables array.
* @param variables Transient variables for the join request.
* @param data Data stream given to the method (might not be zero-terminated
* if data is binary).
* @param data_size Number of bytes in @a data.
* @param jh Join handle to use with GNUNET_PSYC_join_decision()
*/
typedef int
(*GNUNET_PSYC_JoinCallback) (void *cls,
const struct GNUNET_CRYPTO_EddsaPublicKey
*slave_key,
const char *method_name,
size_t variable_count,
const struct GNUNET_ENV_Modifier *variables,
const void *data,
size_t data_size,
struct GNUNET_PSYC_JoinHandle *jh);
/**
* Function to call with the decision made for a join request.
*
* Must be called once and only once in response to an invocation of the
* #GNUNET_PSYC_JoinCallback.
*
* @param jh Join request handle.
* @param is_admitted #GNUNET_YES if joining is approved,
* #GNUNET_NO if it is disapproved.
* @param relay_count Number of relays given.
* @param relays Array of suggested peers that might be useful relays to use
* when joining the multicast group (essentially a list of peers that
* are already part of the multicast group and might thus be willing
* to help with routing). If empty, only this local peer (which must
* be the multicast origin) is a good candidate for building the
* multicast tree. Note that it is unnecessary to specify our own
* peer identity in this array.
* @param method_name Method name for the message transmitted with the response.
* @param env Environment containing transient variables for the message,
* or NULL.
* @param data Data of the message.
* @param data_size Size of @a data.
*/
void
GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
int is_admitted,
uint32_t relay_count,
const struct GNUNET_PeerIdentity *relays,
const char *method_name,
const struct GNUNET_ENV_Environment *env,
const void *data,
size_t data_size);
/**
* Handle for the master of a PSYC channel.
*/
struct GNUNET_PSYC_Master;
/**
* Function called after the channel master started.
*
* @param cls Closure.
* @param last_message_id Last message ID sent to the channel.
*/
typedef void
(*GNUNET_PSYC_MasterStartCallback) (void *cls, uint64_t max_message_id);
/**
* Start a PSYC master channel.
*
* Will start a multicast group identified by the given ECC key. Messages
* received from group members will be given to the respective handler methods.
* If a new member wants to join a group, the "join" method handler will be
* invoked; the join handler must then generate a "join" message to approve the
* joining of the new member. The channel can also change group membership
* without explicit requests. Note that PSYC doesn't itself "understand" join
* or part messages, the respective methods must call other PSYC functions to
* inform PSYC about the meaning of the respective events.
*
* @param cfg Configuration to use (to connect to PSYC service).
* @param channel_key ECC key that will be used to sign messages for this
* PSYC session. The public key is used to identify the PSYC channel.
* Note that end-users will usually not use the private key directly, but
* rather look it up in GNS for places managed by other users, or select
* a file with the private key(s) when setting up their own channels
* FIXME: we'll likely want to use NOT the p521 curve here, but a cheaper
* one in the future.
* @param policy Channel policy specifying join and history restrictions.
* Used to automate join decisions.
* @param method Function to invoke on messages received from slaves.
* @param join_cb Function to invoke when a peer wants to join.
* @param master_started_cb Function to invoke after the channel master started.
* @param cls Closure for @a method and @a join_cb.
* @return Handle for the channel master, NULL on error.
*/
struct GNUNET_PSYC_Master *
GNUNET_PSYC_master_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
const struct GNUNET_CRYPTO_EddsaPrivateKey *channel_key,
enum GNUNET_PSYC_Policy policy,
GNUNET_PSYC_Method method,
GNUNET_PSYC_JoinCallback join_cb,
GNUNET_PSYC_MasterStartCallback master_started_cb,
void *cls);
/**
* Function called to provide data for a transmission via PSYC.
*
* Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
* invalidates the respective transmission handle.
*
* @param cls Closure.
* @param[in,out] data_size Initially set to the number of bytes available in
* @a data, should be set to the number of bytes written to data.
* @param[out] data Where to write the body of the message to give to the
* method. The function must copy at most @a data_size bytes to @a data.
* @return #GNUNET_SYSERR on error (fatal, aborts transmission)
* #GNUNET_NO on success, if more data is to be transmitted later.
* Should be used if @a data_size was not big enough to take all the
* data. If 0 is returned in @a data_size the transmission is paused,
* and can be resumed with GNUNET_PSYC_master_transmit_resume().
* #GNUNET_YES if this completes the transmission (all data supplied)
*/
typedef int
(*GNUNET_PSYC_MasterTransmitNotify) (void *cls,
size_t *data_size,
void *data);
/**
* Flags for transmitting messages to a channel by the master.
*/
enum GNUNET_PSYC_MasterTransmitFlags
{
GNUNET_PSYC_MASTER_TRANSMIT_NONE = 0,
/**
* Whether this message should reset the channel state,
* i.e. remove all previously stored state variables.
*/
GNUNET_PSYC_MASTER_TRANSMIT_RESET_STATE = 1 << 0,
/**
* Whether we need to increment the group generation counter after
* transmitting this message.
*/
GNUNET_PSYC_MASTER_TRANSMIT_INC_GROUP_GEN = 1 << 1,
/**
* Add PSYC header variable with the hash of the current channel state.
*/
GNUNET_PSYC_MASTER_TRANSMIT_ADD_STATE_HASH = 1 << 2
};
/**
* Handle for a pending PSYC transmission operation.
*/
struct GNUNET_PSYC_MasterTransmitHandle;
/**
* Send a message to call a method to all members in the PSYC channel.
*
* @param master Handle to the PSYC channel.
* @param method_name Which method should be invoked.
* @param env Environment containing state operations and transient variables
* for the message, or NULL.
* @param notify Function to call to obtain the arguments.
* @param notify_cls Closure for @a notify.
* @param flags Flags for the message being transmitted.
* @return Transmission handle, NULL on error (i.e. more than one request queued).
*/
struct GNUNET_PSYC_MasterTransmitHandle *
GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
const char *method_name,
const struct GNUNET_ENV_Environment *env,
GNUNET_PSYC_MasterTransmitNotify notify,
void *notify_cls,
enum GNUNET_PSYC_MasterTransmitFlags flags);
/**
* Resume transmission to the channel.
*
* @param th Handle of the request that is being resumed.
*/
void
GNUNET_PSYC_master_transmit_resume (struct GNUNET_PSYC_MasterTransmitHandle *th);
/**
* Abort transmission request to channel.
*
* @param th Handle of the request that is being aborted.
*/
void
GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
/**
* Stop a PSYC master channel.
*
* @param master PSYC channel master to stop.
*/
void
GNUNET_PSYC_master_stop (struct GNUNET_PSYC_Master *master);
/**
* Handle for a PSYC channel slave.
*/
struct GNUNET_PSYC_Slave;
/**
* Function called after the slave joined.
*
* @param cls Closure.
* @param max_message_id Last message ID sent to the channel.
*/
typedef void
(*GNUNET_PSYC_SlaveJoinCallback) (void *cls, uint64_t max_message_id);
/**
* Join a PSYC channel.
*
* The entity joining is always the local peer. The user must immediately use
* the GNUNET_PSYC_slave_transmit() functions to transmit a @e join_msg to the
* channel; if the join request succeeds, the channel state (and @e recent
* method calls) will be replayed to the joining member. There is no explicit
* notification on failure (as the channel may simply take days to approve,
* and disapproval is simply being ignored).
*
* @param cfg Configuration to use.
* @param channel_key ECC public key that identifies the channel we wish to join.
* @param slave_key ECC private-public key pair that identifies the slave, and
* used by multicast to sign the join request and subsequent unicast
* requests sent to the master.
* @param origin Peer identity of the origin.
* @param relay_count Number of peers in the @a relays array.
* @param relays Peer identities of members of the multicast group, which serve
* as relays and used to join the group at.
* @param method Function to invoke on messages received from the channel,
* typically at least contains functions for @e join and @e part.
* @param join_cb function invoked once we have joined with the current
* message ID of the channel
* @param slave_joined_cb Function to invoke when a peer wants to join.
* @param cls Closure for @a method_cb and @a slave_joined_cb.
* @param method_name Method name for the join request.
* @param env Environment containing transient variables for the request, or NULL.
* @param data Payload for the join message.
* @param data_size Number of bytes in @a data.
* @return Handle for the slave, NULL on error.
*/
struct GNUNET_PSYC_Slave *
GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
const struct GNUNET_CRYPTO_EddsaPrivateKey *slave_key,
const struct GNUNET_PeerIdentity *origin,
uint32_t relay_count,
const struct GNUNET_PeerIdentity *relays,
GNUNET_PSYC_Method method,
GNUNET_PSYC_JoinCallback join_cb,
GNUNET_PSYC_SlaveJoinCallback slave_joined_cb,
void *cls,
const char *method_name,
const struct GNUNET_ENV_Environment *env,
const void *data,
uint16_t data_size);
/**
* Part a PSYC channel.
*
* Will terminate the connection to the PSYC service. Polite clients should
* first explicitly send a part request (via GNUNET_PSYC_slave_transmit()).
*
* @param slave Slave handle.
*/
void
GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave);
/**
* Function called to provide data for a transmission to the channel master
* (a.k.a. the @e host of the channel).
*
* Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
* invalidates the respective transmission handle.
*
* @param cls Closure.
* @param[in,out] data_size Initially set to the number of bytes available in
* @a data, should be set to the number of bytes written to data
* (IN/OUT).
* @param[out] data Where to write the body of the message to give to the method;
* function must copy at most @a *data_size bytes to @a data.
* @return #GNUNET_SYSERR on error (fatal, aborts transmission).
* #GNUNET_NO on success, if more data is to be transmitted later.
* #GNUNET_YES if this completes the transmission (all data supplied).
*/
typedef int
(*GNUNET_PSYC_SlaveTransmitNotify) (void *cls,
size_t *data_size,
char *data);
/**
* Flags for transmitting messages to the channel master by a slave.
*/
enum GNUNET_PSYC_SlaveTransmitFlags
{
GNUNET_PSYC_SLAVE_TRANSMIT_NONE = 0
};
/**
* Handle for a pending PSYC transmission operation.
*/
struct GNUNET_PSYC_SlaveTransmitHandle;
/**
* Request a message to be sent to the channel master.
*
* @param slave Slave handle.
* @param method_name Which (PSYC) method should be invoked (on host).
* @param env Environment containing transient variables for the message, or NULL.
* @param notify Function to call when we are allowed to transmit (to get data).
* @param notify_cls Closure for @a notify.
* @param flags Flags for the message being transmitted.
* @return Transmission handle, NULL on error (i.e. more than one request queued).
*/
struct GNUNET_PSYC_SlaveTransmitHandle *
GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
const char *method_name,
const struct GNUNET_ENV_Environment *env,
GNUNET_PSYC_SlaveTransmitNotify notify,
void *notify_cls,
enum GNUNET_PSYC_SlaveTransmitFlags flags);
/**
* Resume transmission to the master.
*
* @param th Handle of the request that is being resumed.
*/
void
GNUNET_PSYC_slave_transmit_resume (struct GNUNET_PSYC_MasterTransmitHandle *th);
/**
* Abort transmission request to master.
*
* @param th Handle of the request that is being aborted.
*/
void
GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
/**
* Handle to access PSYC channel operations for both the master and slaves.
*/
struct GNUNET_PSYC_Channel;
/**
* Convert a channel @a master to a @e channel handle to access the @e channel
* APIs.
*
* @param master Channel master handle.
* @return Channel handle, valid for as long as @a master is valid.
*/
struct GNUNET_PSYC_Channel *
GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
/**
* Convert @a slave to a @e channel handle to access the @e channel APIs.
*
* @param slave Slave handle.
* @return Channel handle, valid for as long as @a slave is valid.
*/
struct GNUNET_PSYC_Channel *
GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
/**
* Add a slave to the channel's membership list.
*
* Note that this will NOT generate any PSYC traffic, it will merely update the
* local database to modify how we react to membership test queries.
* The channel master still needs to explicitly transmit a @e join message to
* notify other channel members and they then also must still call this function
* in their respective methods handling the @e join message. This way, how @e
* join and @e part operations are exactly implemented is still up to the
* application; for example, there might be a @e part_all method to kick out
* everyone.
*
* Note that channel slaves are explicitly trusted to execute such methods
* correctly; not doing so correctly will result in either denying other slaves
* access or offering access to channel data to non-members.
*
* @param channel Channel handle.
* @param slave_key Identity of channel slave to add.
* @param announced_at ID of the message that announced the membership change.
* @param effective_since Addition of slave is in effect since this message ID.
*/
void
GNUNET_PSYC_channel_slave_add (struct GNUNET_PSYC_Channel *channel,
const struct GNUNET_CRYPTO_EddsaPublicKey *slave_key,
uint64_t announced_at,
uint64_t effective_since);
/**
* Remove a slave from the channel's membership list.
*
* Note that this will NOT generate any PSYC traffic, it will merely update the
* local database to modify how we react to membership test queries.
* The channel master still needs to explicitly transmit a @e part message to
* notify other channel members and they then also must still call this function
* in their respective methods handling the @e part message. This way, how
* @e join and @e part operations are exactly implemented is still up to the
* application; for example, there might be a @e part_all message to kick out
* everyone.
*
* Note that channel members are explicitly trusted to perform these
* operations correctly; not doing so correctly will result in either
* denying members access or offering access to channel data to
* non-members.
*
* @param channel Channel handle.
* @param slave_key Identity of channel slave to remove.
* @param announced_at ID of the message that announced the membership change.
*/
void
GNUNET_PSYC_channel_slave_remove (struct GNUNET_PSYC_Channel *channel,
const struct GNUNET_CRYPTO_EddsaPublicKey
*slave_key,
uint64_t announced_at);
/**
* Function called to inform a member about stored state values for a channel.
*
* @param cls Closure.
* @param name Name of the state variable. A NULL value indicates that there
* are no more state variables to be returned.
* @param value Value of the state variable.
* @param value_size Number of bytes in @a value.
*/
typedef void
(*GNUNET_PSYC_StateCallback) (void *cls,
const char *name,
const void *value,
size_t value_size);
/**
* Function called when a requested operation has finished.
*
* @param cls Closure.
*/
typedef void
(*GNUNET_PSYC_FinishCallback) (void *cls);
/**
* Handle to a story telling operation.
*/
struct GNUNET_PSYC_Story;
/**
* Request to be told the message history of the channel.
*
* Historic messages (but NOT the state at the time) will be replayed (given to
* the normal method handlers) if available and if access is permitted.
*
* To get the latest message, use 0 for both the start and end message ID.
*
* @param channel Which channel should be replayed?
* @param start_message_id Earliest interesting point in history.
* @param end_message_id Last (exclusive) interesting point in history.
* @param method Function to invoke on messages received from the story.
* @param finish_cb Function to call when the requested story has been fully
* told (counting message IDs might not suffice, as some messages
* might be secret and thus the listener would not know the story is
* finished without being told explicitly); once this function
* has been called, the client must not call
* GNUNET_PSYC_channel_story_tell_cancel() anymore.
* @param cls Closure for the callbacks.
* @return Handle to cancel story telling operation.
*/
struct GNUNET_PSYC_Story *
GNUNET_PSYC_channel_story_tell (struct GNUNET_PSYC_Channel *channel,
uint64_t start_message_id,
uint64_t end_message_id,
GNUNET_PSYC_Method method,
GNUNET_PSYC_FinishCallback *finish_cb,
void *cls);
/**
* Abort story telling.
*
* This function must not be called from within method handlers (as given to
* GNUNET_PSYC_slave_join()) of the slave.
*
* @param story Story telling operation to stop.
*/
void
GNUNET_PSYC_channel_story_tell_cancel (struct GNUNET_PSYC_Story *story);
/**
* Handle for a state query operation.
*/
struct GNUNET_PSYC_StateQuery;
/**
* Retrieve the best matching channel state variable.
*
* If the requested variable name is not present in the state, the nearest
* less-specific name is matched; for example, requesting "_a_b" will match "_a"
* if "_a_b" does not exist.
*
* @param channel Channel handle.
* @param full_name Full name of the requested variable, the actual variable
* returned might have a shorter name..
* @param cb Function called once when a matching state variable is found.
* Not called if there's no matching state variable.
* @param cb_cls Closure for the callbacks.
* @return Handle that can be used to cancel the query operation.
*/
struct GNUNET_PSYC_StateQuery *
GNUNET_PSYC_channel_state_get (struct GNUNET_PSYC_Channel *channel,
const char *full_name,
GNUNET_PSYC_StateCallback cb,
void *cb_cls);
/**
* Return all channel state variables whose name matches a given prefix.
*
* A name matches if it starts with the given @a name_prefix, thus requesting
* the empty prefix ("") will match all values; requesting "_a_b" will also
* return values stored under "_a_b_c".
*
* The @a state_cb is invoked on all matching state variables asynchronously, as
* the state is stored in and retrieved from the PSYCstore,
*
* @param channel Channel handle.
* @param name_prefix Prefix of the state variable name to match.
* @param cb Function to call with the matching state variables.
* @param cb_cls Closure for the callbacks.
* @return Handle that can be used to cancel the query operation.
*/
struct GNUNET_PSYC_StateQuery *
GNUNET_PSYC_channel_state_get_prefix (struct GNUNET_PSYC_Channel *channel,
const char *name_prefix,
GNUNET_PSYC_StateCallback cb,
void *cb_cls);
/**
* Cancel a state query operation.
*
* @param query Handle for the operation to cancel.
*/
void
GNUNET_PSYC_channel_state_get_cancel (struct GNUNET_PSYC_StateQuery *query);
#if 0 /* keep Emacsens' auto-indent happy */
{
#endif
#ifdef __cplusplus
}
#endif
/* ifndef GNUNET_PSYC_SERVICE_H */
#endif
/* end of gnunet_psyc_service.h */