/* This file is part of GNUnet. Copyright (C) 2009-2016 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 . SPDX-License-Identifier: AGPL3.0-or-later */ /** * @author Christian Grothoff * * @file * Low-level P2P IO * * @defgroup transport Transport service * Low-level P2P IO * * @see [Documentation](https://gnunet.org/transport-service) * * @{ */ #ifndef GNUNET_TRANSPORT_SERVICE_H #define GNUNET_TRANSPORT_SERVICE_H #ifdef __cplusplus extern "C" { #if 0 /* keep Emacsens' auto-indent happy */ } #endif #endif #include "gnunet_util_lib.h" #include "gnunet_ats_service.h" /** * Version number of the transport API. */ #define GNUNET_TRANSPORT_VERSION 0x00000003 /* *************************** HELLO *************************** */ /** * Handle for a #GNUNET_TRANSPORT_offer_hello operation */ struct GNUNET_TRANSPORT_OfferHelloHandle; /** * Offer the transport service the HELLO of another peer. Note that * the transport service may just ignore this message if the HELLO is * malformed or useless due to our local configuration. * * @param cfg configuration * @param hello the hello message * @param cont continuation to call when HELLO has been sent, * tc reason #GNUNET_SCHEDULER_REASON_TIMEOUT for fail * tc reasong #GNUNET_SCHEDULER_REASON_READ_READY for success * @param cont_cls closure for @a cont * @return a `struct GNUNET_TRANSPORT_OfferHelloHandle` handle or NULL on * failure, in case of failure @a cont will not be called * */ struct GNUNET_TRANSPORT_OfferHelloHandle * GNUNET_TRANSPORT_offer_hello (const struct GNUNET_CONFIGURATION_Handle *cfg, const struct GNUNET_MessageHeader *hello, GNUNET_SCHEDULER_TaskCallback cont, void *cont_cls); /** * Cancel the request to transport to offer the HELLO message * * @param ohh the `struct GNUNET_TRANSPORT_OfferHelloHandle` to cancel */ void GNUNET_TRANSPORT_offer_hello_cancel ( struct GNUNET_TRANSPORT_OfferHelloHandle *ohh); /* *********************** Address to String ******************* */ /** * Handle to cancel a pending address lookup. */ struct GNUNET_TRANSPORT_AddressToStringContext; /** * Function to call with a textual representation of an address. This * function will be called several times with different possible * textual representations, and a last time with @a address being NULL * to signal the end of the iteration. Note that @a address NULL * always is the last call, regardless of the value in @a res. * * @param cls closure * @param address NULL on end of iteration, * otherwise 0-terminated printable UTF-8 string, * in particular an empty string if @a res is #GNUNET_NO * @param res result of the address to string conversion: * if #GNUNET_OK: conversion successful * if #GNUNET_NO: address was invalid (or not supported) * if #GNUNET_SYSERR: communication error (IPC error) */ typedef void (*GNUNET_TRANSPORT_AddressToStringCallback) (void *cls, const char *address, int res); /** * Convert a binary address into a human readable address. * * @param cfg configuration to use * @param address address to convert (binary format) * @param numeric should (IP) addresses be displayed in numeric form * (otherwise do reverse DNS lookup) * @param timeout how long is the lookup allowed to take at most * @param aluc function to call with the results * @param aluc_cls closure for @a aluc * @return handle to cancel the operation, NULL on error */ struct GNUNET_TRANSPORT_AddressToStringContext * GNUNET_TRANSPORT_address_to_string ( const struct GNUNET_CONFIGURATION_Handle *cfg, const struct GNUNET_HELLO_Address *address, int numeric, struct GNUNET_TIME_Relative timeout, GNUNET_TRANSPORT_AddressToStringCallback aluc, void *aluc_cls); /** * Cancel request for address conversion. * * @param alc the context handle */ void GNUNET_TRANSPORT_address_to_string_cancel ( struct GNUNET_TRANSPORT_AddressToStringContext *alc); /* *********************** Monitoring ************************** */ /** * Possible state of a neighbour. Initially, we are * #GNUNET_TRANSPORT_PS_NOT_CONNECTED. * * Then, there are two main paths. If we receive a SYN message, we give * the inbound address to ATS. After the check we ask ATS for a suggestion * (#GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS). If ATS makes a suggestion, we * send our SYN_ACK and go to #GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK. * If we receive a ACK, we go to #GNUNET_TRANSPORT_PS_CONNECTED * (and notify everyone about the new connection). If the operation times out, * we go to #GNUNET_TRANSPORT_PS_DISCONNECT. * * The other case is where we transmit a SYN message first. We * start with #GNUNET_TRANSPORT_PS_INIT_ATS. If we get an address, we send * the SYN message and go to state #GNUNET_TRANSPORT_PS_CONNECT_SENT. * Once we receive a SYN_ACK, we go to #GNUNET_TRANSPORT_PS_CONNECTED * (and notify everyone about the new connection and send * back a ACK). If the operation times out, we go to * #GNUNET_TRANSPORT_PS_DISCONNECT. * * If the session is in trouble (i.e. transport-level disconnect or * timeout), we go to #GNUNET_TRANSPORT_PS_RECONNECT_ATS where we ask ATS for a * new address (we don't notify anyone about the disconnect yet). Once we have * a new address, we enter #GNUNET_TRANSPORT_PS_RECONNECT_SENT and send a SYN * message. If we receive a SYN_ACK, we go to #GNUNET_TRANSPORT_PS_CONNECTED * and nobody noticed that we had trouble; we also send a ACK at this time just * in case. If the operation times out, we go to * #GNUNET_TRANSPORT_PS_DISCONNECT (and notify everyone about the lost * connection). * * If ATS decides to switch addresses while we have a normal * connection, we go to #GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_SYN_SENT * and send a SESSION_CONNECT. If we get a ACK back, we switch the * primary connection to the suggested alternative from ATS, go back * to #GNUNET_TRANSPORT_PS_CONNECTED and send a ACK to the other peer just to be * sure. If the operation times out * we go to #GNUNET_TRANSPORT_PS_CONNECTED (and notify ATS that the given * alternative address is "invalid"). * * Once a session is in #GNUNET_TRANSPORT_PS_DISCONNECT, it is cleaned up and * then goes to (#GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED). If we receive an * explicit disconnect request, we can go from any state to * #GNUNET_TRANSPORT_PS_DISCONNECT, possibly after generating disconnect * notifications. * * Note that it is quite possible that while we are in any of these * states, we could receive a 'SYN' request from the other peer. * We then enter a 'weird' state where we pursue our own primary state * machine (as described above), but with the 'send_connect_ack' flag * set to 1. If our state machine allows us to send a 'SYN_ACK' * (because we have an acceptable address), we send the 'SYN_ACK' * and set the 'send_connect_ack' to 2. If we then receive a * 'ACK', we go to #GNUNET_TRANSPORT_PS_CONNECTED (and reset 'send_connect_ack' * to 0). * */ enum GNUNET_TRANSPORT_PeerState { /** * Fresh peer or completely disconnected */ GNUNET_TRANSPORT_PS_NOT_CONNECTED = 0, /** * Asked to initiate connection, trying to get address from ATS */ GNUNET_TRANSPORT_PS_INIT_ATS, /** * Sent SYN message to other peer, waiting for SYN_ACK */ GNUNET_TRANSPORT_PS_SYN_SENT, /** * Received a SYN, asking ATS about address suggestions. */ GNUNET_TRANSPORT_PS_SYN_RECV_ATS, /** * SYN request from other peer was SYN_ACK'ed, waiting for ACK. */ GNUNET_TRANSPORT_PS_SYN_RECV_ACK, /** * Got our SYN_ACK/ACK, connection is up. */ GNUNET_TRANSPORT_PS_CONNECTED, /** * Connection got into trouble, rest of the system still believes * it to be up, but we're getting a new address from ATS. */ GNUNET_TRANSPORT_PS_RECONNECT_ATS, /** * Sent SYN over new address (either by ATS telling us to switch * addresses or from RECONNECT_ATS); if this fails, we need to tell * the rest of the system about a disconnect. */ GNUNET_TRANSPORT_PS_RECONNECT_SENT, /** * We have some primary connection, but ATS suggested we switch * to some alternative; we now sent a SYN message for the * alternative session to the other peer and waiting for a * SYN_ACK to make this our primary connection. */ GNUNET_TRANSPORT_PS_SWITCH_SYN_SENT, /** * Disconnect in progress (we're sending the DISCONNECT message to the * other peer; after that is finished, the state will be cleaned up). */ GNUNET_TRANSPORT_PS_DISCONNECT, /** * We're finished with the disconnect; and are cleaning up the state * now! We put the struct into this state when we are really in the * task that calls 'free' on it and are about to remove the record * from the map. We should never find a 'struct NeighbourMapEntry' * in this state in the map. Accessing a 'struct NeighbourMapEntry' * in this state virtually always means using memory that has been * freed (the exception being the cleanup code in #free_neighbour()). */ GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED }; /** * Convert a transport state to a human readable string. * * @param state the state */ const char * GNUNET_TRANSPORT_ps2s (enum GNUNET_TRANSPORT_PeerState state); /** * Check if a state is defined as connected * * @param state the state value * @return #GNUNET_YES or #GNUNET_NO */ int GNUNET_TRANSPORT_is_connected (enum GNUNET_TRANSPORT_PeerState state); /** * Handle for a #GNUNET_TRANSPORT_monitor_peers operation. */ struct GNUNET_TRANSPORT_PeerMonitoringContext; /** * Function to call with information about a peer * * If one_shot was set to #GNUNET_YES to iterate over all peers once, * a final call with NULL for peer and address will follow when done. * In this case state and timeout do not contain valid values. * * The #GNUNET_TRANSPORT_monitor_peers_cancel() call MUST not be called from * within this function! * * * @param cls closure * @param peer peer this update is about, * NULL if this is the final last callback for a iteration operation * @param address address, NULL if this is the final callback for iteration op * @param state current state this peer is in * @param state_timeout timeout for the current state of the peer */ typedef void (*GNUNET_TRANSPORT_PeerIterateCallback) ( void *cls, const struct GNUNET_PeerIdentity *peer, const struct GNUNET_HELLO_Address *address, enum GNUNET_TRANSPORT_PeerState state, struct GNUNET_TIME_Absolute state_timeout); /** * Return information about a specific peer or all peers currently known to * transport service once or in monitoring mode. To obtain information about * a specific peer, a peer identity can be passed. To obtain information about * all peers currently known to transport service, NULL can be passed as peer * identity. * * For each peer, the callback is called with information about the address used * to communicate with this peer, the state this peer is currently in and the * the current timeout for this state. * * Upon completion, the #GNUNET_TRANSPORT_PeerIterateCallback is called one * more time with `NULL`. After this, the operation must no longer be * explicitly canceled. * * The #GNUNET_TRANSPORT_monitor_peers_cancel call MUST not be called in the * the peer_callback! * * @param cfg configuration to use * @param peer a specific peer identity to obtain information for, * NULL for all peers * @param one_shot #GNUNET_YES to return the current state and then end (with * NULL+NULL), #GNUNET_NO to monitor peers continuously * @param peer_callback function to call with the results * @param peer_callback_cls closure for @a peer_callback */ struct GNUNET_TRANSPORT_PeerMonitoringContext * GNUNET_TRANSPORT_monitor_peers ( const struct GNUNET_CONFIGURATION_Handle *cfg, const struct GNUNET_PeerIdentity *peer, int one_shot, GNUNET_TRANSPORT_PeerIterateCallback peer_callback, void *peer_callback_cls); /** * Cancel request to monitor peers * * @param pic handle for the request to cancel */ void GNUNET_TRANSPORT_monitor_peers_cancel ( struct GNUNET_TRANSPORT_PeerMonitoringContext *pic); /* *********************** Blacklisting ************************ */ /** * Handle for blacklisting peers. */ struct GNUNET_TRANSPORT_Blacklist; /** * Function that decides if a connection is acceptable or not. * * @param cls closure * @param pid peer to approve or disapproave * @return #GNUNET_OK if the connection is allowed, #GNUNET_SYSERR if not */ typedef int (*GNUNET_TRANSPORT_BlacklistCallback) ( void *cls, const struct GNUNET_PeerIdentity *pid); /** * Install a blacklist callback. The service will be queried for all * existing connections as well as any fresh connections to check if * they are permitted. If the blacklisting callback is unregistered, * all hosts that were denied in the past will automatically be * whitelisted again. Cancelling the blacklist handle is also the * only way to re-enable connections from peers that were previously * blacklisted. * * @param cfg configuration to use * @param cb callback to invoke to check if connections are allowed * @param cb_cls closure for @a cb * @return NULL on error, otherwise handle for cancellation */ struct GNUNET_TRANSPORT_Blacklist * GNUNET_TRANSPORT_blacklist (const struct GNUNET_CONFIGURATION_Handle *cfg, GNUNET_TRANSPORT_BlacklistCallback cb, void *cb_cls); /** * Abort the blacklist. Note that this function is the only way for * removing a peer from the blacklist. * * @param br handle of the request that is to be cancelled */ void GNUNET_TRANSPORT_blacklist_cancel (struct GNUNET_TRANSPORT_Blacklist *br); /** * Handle for a plugin session state monitor. */ struct GNUNET_TRANSPORT_PluginMonitor; /** * Abstract representation of a plugin's session. * Corresponds to the `struct GNUNET_ATS_Session` within the TRANSPORT service. */ struct GNUNET_TRANSPORT_PluginSession; /** * Possible states of a session in a plugin. */ enum GNUNET_TRANSPORT_SessionState { /** * The session was created (first call for each session object). */ GNUNET_TRANSPORT_SS_INIT, /** * Initial session handshake is in progress. */ GNUNET_TRANSPORT_SS_HANDSHAKE, /** * Session is fully UP. */ GNUNET_TRANSPORT_SS_UP, /** * This is just an update about the session, * the state did not change. */ GNUNET_TRANSPORT_SS_UPDATE, /** * Session is being torn down and about to disappear. * Last call for each session object. */ GNUNET_TRANSPORT_SS_DONE }; /** * Information about a plugin's session. */ struct GNUNET_TRANSPORT_SessionInfo { /** * New state of the session. */ enum GNUNET_TRANSPORT_SessionState state; /** * #GNUNET_YES if this is an inbound connection, * #GNUNET_NO if this is an outbound connection, * #GNUNET_SYSERR if connections of this plugin * are so fundamentally bidirectional * that they have no 'initiator' */ int is_inbound; /** * Number of messages pending transmission for this session. */ uint32_t num_msg_pending; /** * Number of bytes pending transmission for this session. */ uint32_t num_bytes_pending; /** * Until when does this plugin refuse to receive to manage * staying within the inbound quota? ZERO if receive is * active. */ struct GNUNET_TIME_Absolute receive_delay; /** * At what time will this session timeout (unless activity * happens)? */ struct GNUNET_TIME_Absolute session_timeout; /** * Address used by the session. Can be NULL if none is available. */ const struct GNUNET_HELLO_Address *address; }; /** * Function called by the plugin with information about the * current sessions managed by the plugin (for monitoring). * * @param cls closure * @param session session handle this information is about, * NULL to indicate that we are "in sync" (initial * iteration complete) * @param session_ctx storage location where the application * can store data; will point to NULL on #GNUNET_TRANSPORT_SS_INIT, * and must be reset to NULL on #GNUNET_TRANSPORT_SS_DONE * @param info information about the state of the session, * NULL if @a session is also NULL and we are * merely signalling that the initial iteration is over; * NULL with @a session being non-NULL if the monitor * was being cancelled while sessions were active */ typedef void (*GNUNET_TRANSPORT_SessionMonitorCallback) ( void *cls, struct GNUNET_TRANSPORT_PluginSession *session, void **session_ctx, const struct GNUNET_TRANSPORT_SessionInfo *info); /** * Install a plugin session state monitor callback. The callback * will be notified whenever the session changes. * * @param cfg configuration to use * @param cb callback to invoke on events * @param cb_cls closure for @a cb * @return NULL on error, otherwise handle for cancellation */ struct GNUNET_TRANSPORT_PluginMonitor * GNUNET_TRANSPORT_monitor_plugins (const struct GNUNET_CONFIGURATION_Handle *cfg, GNUNET_TRANSPORT_SessionMonitorCallback cb, void *cb_cls); /** * Cancel monitoring the plugin session state. The callback will be * called once for each session that is up with the "info" argument * being NULL (this is just to enable client-side cleanup). * * @param pm handle of the request that is to be cancelled */ void GNUNET_TRANSPORT_monitor_plugins_cancel ( struct GNUNET_TRANSPORT_PluginMonitor *pm); /** * Opaque handle to the service. */ struct GNUNET_TRANSPORT_CoreHandle; /** * Function called to notify transport users that another * peer connected to us. * * @param cls closure * @param peer the identity of the peer that connected; this * pointer will remain valid until the disconnect, hence * applications do not necessarily have to make a copy * of the value if they only need it until disconnect * @param mq message queue to use to transmit to @a peer * @return closure to use in MQ handlers */ typedef void *(*GNUNET_TRANSPORT_NotifyConnect) ( void *cls, const struct GNUNET_PeerIdentity *peer, struct GNUNET_MQ_Handle *mq); /** * Function called to notify transport users that another peer * disconnected from us. The message queue that was given to the * connect notification will be destroyed and must not be used * henceforth. * * @param cls closure from #GNUNET_TRANSPORT_core_connect * @param peer the peer that disconnected * @param handlers_cls closure of the handlers, was returned from the * connect notification callback */ typedef void (*GNUNET_TRANSPORT_NotifyDisconnect) ( void *cls, const struct GNUNET_PeerIdentity *peer, void *handler_cls); /** * Function called if we have "excess" bandwidth to a peer. * The notification will happen the first time we have excess * bandwidth, and then only again after the client has performed * some transmission to the peer. * * Excess bandwidth is defined as being allowed (by ATS) to send * more data, and us reaching the limit of the capacity build-up * (which, if we go past it, means we don't use available bandwidth). * See also the "max carry" in `struct GNUNET_BANDWIDTH_Tracker`. * * @param cls the closure * @param neighbour peer that we have excess bandwidth to * @param handlers_cls closure of the handlers, was returned from the * connect notification callback */ typedef void (*GNUNET_TRANSPORT_NotifyExcessBandwidth) ( void *cls, const struct GNUNET_PeerIdentity *neighbour, void *handlers_cls); /** * Connect to the transport service. Note that the connection may * complete (or fail) asynchronously. * * @param cfg configuration to use * @param self our own identity (API should check that it matches * the identity found by transport), or NULL (no check) * @param handlers array of message handlers; note that the * closures provided will be ignored and replaced * with the respective return value from @a nc * @param handlers array with handlers to call when we receive messages, or NULL * @param cls closure for the @a nc, @a nd and @a neb callbacks * @param nc function to call on connect events, or NULL * @param nd function to call on disconnect events, or NULL * @param neb function to call if we have excess bandwidth to a peer, or NULL * @return NULL on error */ struct GNUNET_TRANSPORT_CoreHandle * GNUNET_TRANSPORT_core_connect (const struct GNUNET_CONFIGURATION_Handle *cfg, const struct GNUNET_PeerIdentity *self, const struct GNUNET_MQ_MessageHandler *handlers, void *cls, GNUNET_TRANSPORT_NotifyConnect nc, GNUNET_TRANSPORT_NotifyDisconnect nd, GNUNET_TRANSPORT_NotifyExcessBandwidth neb); /** * Disconnect from the transport service. * * @param handle handle returned from connect */ void GNUNET_TRANSPORT_core_disconnect (struct GNUNET_TRANSPORT_CoreHandle *handle); /** * Checks if a given peer is connected to us and get the message queue. * * @param handle connection to transport service * @param peer the peer to check * @return NULL if disconnected, otherwise message queue for @a peer */ struct GNUNET_MQ_Handle * GNUNET_TRANSPORT_core_get_mq (struct GNUNET_TRANSPORT_CoreHandle *handle, const struct GNUNET_PeerIdentity *peer); #if 0 /* keep Emacsens' auto-indent happy */ { #endif #ifdef __cplusplus } #endif /* ifndef GNUNET_TRANSPORT_SERVICE_H */ #endif /** @} */ /* end of group */ /* end of gnunet_transport_service.h */