/* * Copyright (c) 2012, The Tor Project, Inc. */ /* See LICENSE for licensing information */ /** * \file channel.h * \brief Header file for channel.c **/ #ifndef _TOR_CHANNEL_H #define _TOR_CHANNEL_H #include "or.h" /* * Channel struct; see thw channel_t typedef in or.h. A channel is an * abstract interface for the OR-to-OR connection, similar to connection_or_t, * but without the strong coupling to the underlying TLS implementation. They * are constructed by calling a protocol-specific function to open a channel * to a particular node, and once constructed support the abstract operations * defined below. */ struct channel_s { /* Current channel state */ channel_state_t state; /* Globally unique ID number for a channel over the lifetime of a Tor * process. */ uint64_t global_identifier; /* Should we expect to see this channel in the channel lists? */ unsigned char registered:1; /** Set this if this channel is created in CHANNEL_STATE_LISTEN, so * lower-layer close methods that see the channel in CHANNEL_STATE_CLOSING * know. */ unsigned int is_listener:1; /** Unique ID for measuring direct network status requests;vtunneled ones * come over a circuit_t, which has a dirreq_id field as well, but is a * distinct namespace. */ uint64_t dirreq_id; /** Why did we close? */ enum { CHANNEL_NOT_CLOSING = 0, CHANNEL_CLOSE_REQUESTED, CHANNEL_CLOSE_FROM_BELOW, CHANNEL_CLOSE_FOR_ERROR } reason_for_closing; /* Timestamps for both cell channels and listeners */ time_t timestamp_created; /* Channel created */ time_t timestamp_active; /* Any activity */ /* Methods implemented by the lower layer */ /* Free a channel */ void (*free)(channel_t *); /* Close an open channel */ void (*close)(channel_t *); union { struct { /* Registered listen handler to call on incoming connection */ void (*listener)(channel_t *, channel_t *); /* List of pending incoming connections */ smartlist_t *incoming_list; } listener; struct { /* Registered handlers for incoming cells */ void (*cell_handler)(channel_t *, cell_t *); void (*var_cell_handler)(channel_t *, var_cell_t *); /* Methods implemented by the lower layer */ /* * Ask the underlying transport what the remote endpoint address is, in * a tor_addr_t. This is optional and subclasses may leave this NULL. * If they implement it, they should write the address out to the * provided tor_addr_t *, and return 1 if successful or 0 if no address * available. */ int (*get_remote_addr)(channel_t *, tor_addr_t *); /* * Get a text description of the remote endpoint; canonicalized if the * arg is 0, or the one we originally connected to/received from if it's * 1. */ const char * (*get_remote_descr)(channel_t *, int); /* Check if the lower layer has queued writes */ int (*has_queued_writes)(channel_t *); /* * If the second param is zero, ask the lower layer if this is * 'canonical', for a transport-specific definition of canonical; if * it is 1, ask if the answer to the preceding query is safe to rely * on. */ int (*is_canonical)(channel_t *, int); /* Check if this channel matches a specified extend_info_t */ int (*matches_extend_info)(channel_t *, extend_info_t *); /* Check if this channel matches a target address when extending */ int (*matches_target)(channel_t *, const tor_addr_t *); /* Write a cell to an open channel */ int (*write_cell)(channel_t *, cell_t *); /* Write a packed cell to an open channel */ int (*write_packed_cell)(channel_t *, packed_cell_t *); /* Write a variable-length cell to an open channel */ int (*write_var_cell)(channel_t *, var_cell_t *); /* * Hash of the public RSA key for the other side's identity key, or * zeroes if the other side hasn't shown us a valid identity key. */ char identity_digest[DIGEST_LEN]; /* Nickname of the OR on the other side, or NULL if none. */ char *nickname; /* * Linked list of channels with the same identity digest, for the * digest->channel map */ channel_t *next_with_same_id, *prev_with_same_id; /* List of incoming cells to handle */ smartlist_t *cell_queue; /* List of queued outgoing cells */ smartlist_t *outgoing_queue; /* * When we last used this conn for any client traffic. If not * recent, we can rate limit it further. */ time_t client_used; /* Circuit stuff for use by relay.c */ /* * Double-linked ring of circuits with queued cells waiting for room to * free up on this connection's outbuf. Every time we pull cells from * a circuit, we advance this pointer to the next circuit in the ring. */ struct circuit_t *active_circuits; /* * Priority queue of cell_ewma_t for circuits with queued cells waiting * for room to free up on this connection's outbuf. Kept in heap order * according to EWMA. * * This is redundant with active_circuits; if we ever decide only to use * the cell_ewma algorithm for choosing circuits, we can remove * active_circuits. */ smartlist_t *active_circuit_pqueue; /* * The tick on which the cell_ewma_ts in active_circuit_pqueue last had * their ewma values rescaled. */ unsigned active_circuit_pqueue_last_recalibrated; /* Circuit ID generation stuff for use by circuitbuild.c */ /* * When we send CREATE cells along this connection, which half of the * space should we use? */ circ_id_type_t circ_id_type:2; /* * Which circ_id do we try to use next on this connection? This is * always in the range 0..1<<15-1. */ circid_t next_circ_id; /* How many circuits use this connection as p_chan or n_chan? */ int n_circuits; /* * True iff this channel shouldn't get any new circs attached to it, * because the connection is too old, or because there's a better one. * More generally, this flag is used to note an unhealthy connection; * for example, if a bad connection fails we shouldn't assume that the * router itself has a problem. */ unsigned int is_bad_for_new_circs:1; /** True iff we have decided that the other end of this connection * is a client. Channels with this flag set should never be used * to satisfy an EXTEND request. */ unsigned int is_client:1; /** Set if the channel was initiated remotely (came from a listener) */ unsigned int is_incoming:1; /** Set by lower layer if this is local; i.e., everything it communicates * with for this channel returns true for is_local_addr(). This is used * to decide whether to declare reachability when we receive something on * this channel in circuitbuild.c */ unsigned int is_local:1; /** Channel timestamps for cell channels */ time_t timestamp_client; /* Client used this, according to relay.c */ time_t timestamp_drained; /* Output queue empty */ time_t timestamp_recv; /* Cell received from lower layer */ time_t timestamp_xmit; /* Cell sent to lower layer */ /* Timestamp for relay.c */ time_t timestamp_last_added_nonpadding; /** Unique ID for measuring direct network status requests;vtunneled ones * come over a circuit_t, which has a dirreq_id field as well, but is a * distinct namespace. */ uint64_t dirreq_id; } cell_chan; } u; }; /* Channel state manipulations */ int channel_state_is_valid(channel_state_t state); int channel_state_can_transition(channel_state_t from, channel_state_t to); const char * channel_state_to_string(channel_state_t state); /* Abstract channel operations */ void channel_request_close(channel_t *chan); void channel_write_cell(channel_t *chan, cell_t *cell); void channel_write_packed_cell(channel_t *chan, packed_cell_t *cell); void channel_write_var_cell(channel_t *chan, var_cell_t *cell); /* Channel callback registrations */ /* Listener callback */ void (* channel_get_listener(channel_t *chan))(channel_t *, channel_t *); void channel_set_listener(channel_t *chan, void (*listener)(channel_t *, channel_t *) ); /* Incoming cell callbacks */ void (* channel_get_cell_handler(channel_t *chan)) (channel_t *, cell_t *); void (* channel_get_var_cell_handler(channel_t *chan)) (channel_t *, var_cell_t *); void channel_set_cell_handler(channel_t *chan, void (*cell_handler)(channel_t *, cell_t *)); void channel_set_cell_handlers(channel_t *chan, void (*cell_handler)(channel_t *, cell_t *), void (*var_cell_handler)(channel_t *, var_cell_t *)); void channel_set_var_cell_handler(channel_t *chan, void (*var_cell_handler)(channel_t *, var_cell_t *)); /* Clean up closed channels periodically; called from run_scheduled_events() * in main.c */ void channel_run_cleanup(void); /* Close all channels and deallocate everything */ void channel_free_all(void); #ifdef _TOR_CHANNEL_INTERNAL /* Channel operations for subclasses and internal use only */ /* Initialize a newly allocated channel - do this first in subclass * constructors. */ void channel_init_for_cells(channel_t *chan); void channel_init_listener(channel_t *chan); /* Channel registration/unregistration */ void channel_register(channel_t *chan); void channel_unregister(channel_t *chan); /* Close from below */ void channel_close_from_lower_layer(channel_t *chan); void channel_close_for_error(channel_t *chan); void channel_closed(channel_t *chan); /* Free a channel */ void channel_free(channel_t *chan); void channel_force_free(channel_t *chan); /* State/metadata setters */ void channel_change_state(channel_t *chan, channel_state_t to_state); void channel_clear_identity_digest(channel_t *chan); void channel_clear_remote_end(channel_t *chan); void channel_mark_local(channel_t *chan); void channel_mark_incoming(channel_t *chan); void channel_mark_outgoing(channel_t *chan); void channel_set_identity_digest(channel_t *chan, const char *identity_digest); void channel_set_remote_end(channel_t *chan, const char *identity_digest, const char *nickname); /* Timestamp updates */ void channel_timestamp_created(channel_t *chan); void channel_timestamp_active(channel_t *chan); void channel_timestamp_drained(channel_t *chan); void channel_timestamp_recv(channel_t *chan); void channel_timestamp_xmit(channel_t *chan); /* Incoming channel handling */ void channel_process_incoming(channel_t *listener); void channel_queue_incoming(channel_t *listener, channel_t *incoming); /* Incoming cell handling */ void channel_process_cells(channel_t *chan); void channel_queue_cell(channel_t *chan, cell_t *cell); void channel_queue_var_cell(channel_t *chan, var_cell_t *var_cell); /* Outgoing cell handling */ void channel_flush_cells(channel_t *chan); /* Request from lower layer for more cells if available */ ssize_t channel_flush_some_cells(channel_t *chan, ssize_t num_cells); /* Query if data available on this channel */ int channel_more_to_flush(channel_t *chan); /* Notify flushed outgoing for dirreq handling */ void channel_notify_flushed(channel_t *chan); /* Handle stuff we need to do on open like notifying circuits */ void channel_do_open_actions(channel_t *chan); #endif /* Helper functions to perform operations on channels */ int channel_send_destroy(circid_t circ_id, channel_t *chan, int reason); /* * Outside abstract interfaces that should eventually get turned into * something transport/address format independent. */ channel_t * channel_connect(const tor_addr_t *addr, uint16_t port, const char *id_digest); channel_t * channel_get_for_extend(const char *digest, const tor_addr_t *target_addr, const char **msg_out, int *launch_out); /* Ask which of two channels is better for circuit-extension purposes */ int channel_is_better(time_t now, channel_t *a, channel_t *b, int forgive_new_connections); /** Channel lookups */ channel_t * channel_find_by_global_id(uint64_t global_identifier); channel_t * channel_find_by_remote_digest(const char *identity_digest); channel_t * channel_find_by_remote_nickname(const char *nickname); /** For things returned by channel_find_by_remote_digest(), walk the list. */ channel_t * channel_next_with_digest(channel_t *chan); channel_t * channel_prev_with_digest(channel_t *chan); /* * Metadata queries/updates */ const char * channel_get_actual_remote_descr(channel_t *chan); int channel_get_addr_if_possible(channel_t *chan, tor_addr_t *addr_out); const char * channel_get_canonical_remote_descr(channel_t *chan); int channel_has_queued_writes(channel_t *chan); int channel_is_bad_for_new_circs(channel_t *chan); void channel_mark_bad_for_new_circs(channel_t *chan); int channel_is_canonical(channel_t *chan); int channel_is_canonical_is_reliable(channel_t *chan); int channel_is_client(channel_t *chan); int channel_is_local(channel_t *chan); int channel_is_incoming(channel_t *chan); int channel_is_outgoing(channel_t *chan); void channel_mark_client(channel_t *chan); int channel_matches_extend_info(channel_t *chan, extend_info_t *extend_info); int channel_matches_target_addr_for_extend(channel_t *chan, const tor_addr_t *target); void channel_set_circid_type(channel_t *chan, crypto_pk_t *identity_rcvd); void channel_timestamp_client(channel_t *chan); /* Timestamp queries */ time_t channel_when_created(channel_t *chan); time_t channel_when_last_active(channel_t *chan); time_t channel_when_last_client(channel_t *chan); time_t channel_when_last_drained(channel_t *chan); time_t channel_when_last_recv(channel_t *chan); time_t channel_when_last_xmit(channel_t *chan); #endif