/* 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_transport_plugin.h * @brief API for the transport services. This header * specifies the struct that is given to the plugin's entry * method and the other struct that must be returned. * Note that the destructors of transport plugins will * be given the value returned by the constructor * and is expected to return a NULL pointer. * @author Christian Grothoff */ #ifndef PLUGIN_TRANSPORT_H #define PLUGIN_TRANSPORT_H #include "gnunet_configuration_lib.h" #include "gnunet_scheduler_lib.h" #include "gnunet_statistics_service.h" #include "gnunet_transport_service.h" /** * Opaque pointer that plugins can use to distinguish specific * connections to a given peer. Typically used by stateful plugins to * allow the service to refer to specific streams instead of a more * general notion of "some connection" to the given peer. This is * useful since sometimes (i.e. for inbound TCP connections) a * connection may not have an address that can be used for meaningful * distinction between sessions to the same peer. * * Each 'struct Session' MUST start with the 'struct GNUNET_PeerIdentity' * of the peer the session is for (which will be used for some error * checking by the ATS code). */ struct Session; /** * Every 'struct Session' must begin with this header. */ struct SessionHeader { /* empty, for now */ }; /** * Function that will be called whenever the plugin internally * cleans up a session pointer and hence the service needs to * discard all of those sessions as well. Plugins that do not * use sessions can simply omit calling this function and always * use NULL wherever a session pointer is needed. This function * should be called BEFORE a potential "TransmitContinuation" * from the "TransmitFunction". * * @param cls closure * @param peer which peer was the session for * @param session which session is being destoyed */ typedef void (*GNUNET_TRANSPORT_SessionEnd) (void *cls, const struct GNUNET_PeerIdentity * peer, struct Session * session); /** * Function called by the transport for each received message. * This function should also be called with "NULL" for the * message to signal that the other peer disconnected. * * @param cls closure * @param peer (claimed) identity of the other peer * @param message the message, NULL if we only care about * learning about the delay until we should receive again * @param session identifier used for this session (NULL for plugins * that do not offer bi-directional communication to the sender * using the same "connection") * @param sender_address binary address of the sender (if we established the * connection or are otherwise sure of it; should be NULL * for inbound TCP/UDP connections since it it not clear * that we could establish ourselves a connection to that * IP address and get the same system) * @param sender_address_len number of bytes in sender_address * @return how long the plugin should wait until receiving more data * (plugins that do not support this, can ignore the return value) */ typedef struct GNUNET_TIME_Relative (*GNUNET_TRANSPORT_PluginReceiveCallback) (void *cls, const struct GNUNET_PeerIdentity *peer, const struct GNUNET_MessageHeader *message, struct Session *session, const char *sender_address, uint16_t sender_address_len); /** * Function that will be called to figure if an address is an loopback, * LAN, WAN etc. address * * @param cls closure * @param addr binary address * @param addrlen length of the address * @return ATS Information containing the network type */ typedef struct GNUNET_ATS_Information (*GNUNET_TRANSPORT_AddressToType) (void *cls, const struct sockaddr *addr, size_t addrlen); /** * Function called when quality properties of an address change. * * @param cls closure * @param peer peer * @param address address * @param address_len length of the address * @param session session * @param ats ATS information * @param ats_count number of ATS information contained */ typedef void (*GNUNET_TRANSPORT_UpdateAddressMetrics) (void *cls, const struct GNUNET_PeerIdentity *peer, const void *address, uint16_t address_len, struct Session *session, const struct GNUNET_ATS_Information *ats, uint32_t ats_count); /** * Function that will be called for each address the transport * is aware that it might be reachable under. * * @param cls closure * @param add_remove should the address added (YES) or removed (NO) from the * set of valid addresses? * @param addr one of the addresses of the host * the specific address format depends on the transport * @param addrlen length of the address * @param dest_plugin plugin to use this address with */ typedef void (*GNUNET_TRANSPORT_AddressNotification) (void *cls, int add_remove, const void *addr, size_t addrlen, const char *dest_plugin); /** * Function that will be called whenever the plugin receives data over * the network and wants to determine how long it should wait until * the next time it reads from the given peer. Note that some plugins * (such as UDP) may not be able to wait (for a particular peer), so * the waiting part is optional. Plugins that can wait should call * this function, sleep the given amount of time, and call it again * (with zero bytes read) UNTIL it returns zero and only then read. * * @param cls closure * @param peer which peer did we read data from * @param amount_recved number of bytes read (can be zero) * @return how long to wait until reading more from this peer * (to enforce inbound quotas) */ typedef struct GNUNET_TIME_Relative (*GNUNET_TRANSPORT_TrafficReport) (void *cls, const struct GNUNET_PeerIdentity * peer, size_t amount_recved); /** * Function that returns a HELLO message. */ typedef const struct GNUNET_MessageHeader * (*GNUNET_TRANSPORT_GetHelloCallback) (void); /** * The transport service will pass a pointer to a struct * of this type as the first and only argument to the * entry point of each transport plugin. */ struct GNUNET_TRANSPORT_PluginEnvironment { /** * Configuration to use. */ const struct GNUNET_CONFIGURATION_Handle *cfg; /** * Identity of this peer. */ const struct GNUNET_PeerIdentity *my_identity; /** * Closure for the various callbacks. */ void *cls; /** * Handle for reporting statistics. */ struct GNUNET_STATISTICS_Handle *stats; /** * Function that should be called by the transport plugin * whenever a message is received. If this field is "NULL", * the plugin should load in 'stub' mode and NOT fully * initialize and instead only return an API with the * 'address_pretty_printer', 'address_to_string' and * 'string_to_address' functions. */ GNUNET_TRANSPORT_PluginReceiveCallback receive; /** * Function that returns our HELLO. */ GNUNET_TRANSPORT_GetHelloCallback get_our_hello; /** * Function that must be called by each plugin to notify the * transport service about the addresses under which the transport * provided by the plugin can be reached. */ GNUNET_TRANSPORT_AddressNotification notify_address; /** * Function that must be called by the plugin when a non-NULL * session handle stops being valid (is destroyed). */ GNUNET_TRANSPORT_SessionEnd session_end; /** * Function that will be called to figure if an address is an loopback, * LAN, WAN etc. address */ GNUNET_TRANSPORT_AddressToType get_address_type; /** * Function that will be called to figure if an address is an loopback, * LAN, WAN etc. address */ GNUNET_TRANSPORT_UpdateAddressMetrics update_address_metrics; /** * What is the maximum number of connections that this transport * should allow? Transports that do not have sessions (such as * UDP) can ignore this value. */ uint32_t max_connections; }; /** * Function called by the GNUNET_TRANSPORT_TransmitFunction * upon "completion". In the case that a peer disconnects, * this function must be called for each pending request * (with a 'failure' indication) AFTER notifying the service * about the disconnect event (so that the service won't try * to transmit more messages, believing the connection still * exists...). * * @param cls closure * @param target who was the recipient of the message? * @param result GNUNET_OK on success * GNUNET_SYSERR if the target disconnected; * disconnect will ALSO be signalled using * the ReceiveCallback. * @param size_payload bytes of payload from transport service in message * @param size_on_wire bytes required on wire for transmission, * 0 if result == GNUNET_SYSERR */ typedef void (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls, const struct GNUNET_PeerIdentity * target, int result, size_t size_payload, size_t size_on_wire); /** * The new send function with just the session and no address * * Function that can be used by the transport service to transmit * a message using the plugin. Note that in the case of a * peer disconnecting, the continuation MUST be called * prior to the disconnect notification itself. This function * will be called with this peer's HELLO message to initiate * a fresh connection to another peer. * * @param cls closure * @param session which session must be used * @param msgbuf the message to transmit * @param msgbuf_size number of bytes in 'msgbuf' * @param priority how important is the message (most plugins will * ignore message priority and just FIFO) * @param timeout how long to wait at most for the transmission (does not * require plugins to discard the message after the timeout, * just advisory for the desired delay; most plugins will ignore * this as well) * @param cont continuation to call once the message has * been transmitted (or if the transport is ready * for the next transmission call; or if the * peer disconnected...); can be NULL * @param cont_cls closure for cont * @return number of bytes used (on the physical network, with overheads); * -1 on hard errors (i.e. address invalid); 0 is a legal value * and does NOT mean that the message was not transmitted (DV) */ typedef ssize_t (*GNUNET_TRANSPORT_TransmitFunction) (void *cls, struct Session *session, const char *msgbuf, size_t msgbuf_size, unsigned int priority, struct GNUNET_TIME_Relative to, GNUNET_TRANSPORT_TransmitContinuation cont, void *cont_cls); /** * Function that can be called to force a disconnect from the * specified neighbour. This should also cancel all previously * scheduled transmissions. Obviously the transmission may have been * partially completed already, which is OK. The plugin is supposed * to close the connection (if applicable) and no longer call the * transmit continuation(s). * * Finally, plugin MUST NOT call the services's receive function to * notify the service that the connection to the specified target was * closed after a getting this call. * * @param cls closure * @param target peer for which the last transmission is * to be cancelled */ typedef void (*GNUNET_TRANSPORT_DisconnectFunction) (void *cls, const struct GNUNET_PeerIdentity * target); /** * Function called by the pretty printer for the resolved address for * each human-readable address obtained. * * @param cls closure * @param hostname one of the names for the host, NULL * on the last call to the callback */ typedef void (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls, const char *address); /** * Convert the transports address to a nice, human-readable * format. * * @param cls closure * @param name name of the transport that generated the address * @param addr one of the addresses of the host, NULL for the last address * the specific address format depends on the transport * @param addrlen length of the address * @param numeric should (IP) addresses be displayed in numeric form? * @param timeout after how long should we give up? * @param asc function to call on each string * @param asc_cls closure for asc */ typedef void (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls, const char *type, const void *addr, size_t addrlen, int numeric, struct GNUNET_TIME_Relative timeout, GNUNET_TRANSPORT_AddressStringCallback asc, void *asc_cls); /** * Another peer has suggested an address for this peer and transport * plugin. Check that this could be a valid address. This function * is not expected to 'validate' the address in the sense of trying to * connect to it but simply to see if the binary format is technically * legal for establishing a connection to this peer (and make sure that * the address really corresponds to our network connection/settings * and not some potential man-in-the-middle). * * @param addr pointer to the address * @param addrlen length of addr * @return GNUNET_OK if this is a plausible address for this peer * and transport, GNUNET_SYSERR if not */ typedef int (*GNUNET_TRANSPORT_CheckAddress) (void *cls, const void *addr, size_t addrlen); /** * Create a new session to transmit data to the target * This session will used to send data to this peer and the plugin will * notify us by calling the env->session_end function * * @param cls the plugin * @param target the neighbour id * @param addr pointer to the address * @param addrlen length of addr * @return the session if the address is valid, NULL otherwise */ typedef struct Session * (*GNUNET_TRANSPORT_CreateSession) (void *cls, const struct GNUNET_HELLO_Address *address); /** * Function called for a quick conversion of the binary address to * a numeric address. Note that the caller must not free the * address and that the next call to this function is allowed * to override the address again. * * @param cls closure * @param addr binary address * @param addr_len length of the address * @return string representing the same address */ typedef const char *(*GNUNET_TRANSPORT_AddressToString) (void *cls, const void *addr, size_t addrlen); /** * Function called to convert a string address to * a binary address. * * @param cls closure ('struct Plugin*') * @param addr string address * @param addrlen length of the address including \0 termination * @param buf location to store the buffer * If the function returns GNUNET_SYSERR, its contents are undefined. * @param added length of created address * @return GNUNET_OK on success, GNUNET_SYSERR on failure */ typedef int (*GNUNET_TRANSPORT_StringToAddress) (void *cls, const char *addr, uint16_t addrlen, void **buf, size_t *added); /** * Each plugin is required to return a pointer to a struct of this * type as the return value from its entry point. */ struct GNUNET_TRANSPORT_PluginFunctions { /** * Closure for all of the callbacks. */ void *cls; /** * Function that the transport service will use to transmit data to * another peer. May be NULL for plugins that only support * receiving data. After this call, the plugin call the specified * continuation with success or error before notifying us about the * target having disconnected. */ GNUNET_TRANSPORT_TransmitFunction send; /** * Function that can be used to force the plugin to disconnect from * the given peer and cancel all previous transmissions (and their * continuations). */ GNUNET_TRANSPORT_DisconnectFunction disconnect; /** * Function to pretty-print addresses. NOTE: this function is not * yet used by transport-service, but will be used in the future * once the transport-API has been completed. */ GNUNET_TRANSPORT_AddressPrettyPrinter address_pretty_printer; /** * Function that will be called to check if a binary address * for this plugin is well-formed and corresponds to an * address for THIS peer (as per our configuration). Naturally, * if absolutely necessary, plugins can be a bit conservative in * their answer, but in general plugins should make sure that the * address does not redirect traffic to a 3rd party that might * try to man-in-the-middle our traffic. */ GNUNET_TRANSPORT_CheckAddress check_address; /** * Function that will be called to convert a binary address * to a string (numeric conversion only). */ GNUNET_TRANSPORT_AddressToString address_to_string; /** * Function that will be called to convert a string address * to binary (numeric conversion only). */ GNUNET_TRANSPORT_StringToAddress string_to_address; /** * Function that will be called tell the plugin to create a session * object */ GNUNET_TRANSPORT_CreateSession get_session; }; #endif