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Tor
0.4.7.0-alpha-dev
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OR/OP-to-OR channel abstraction layer. A channel's job is to transfer cells from Tor instance to Tor instance. Currently, there is only one implementation of the channel abstraction: in channeltls.c. More...
#include "core/or/or.h"#include "app/config/config.h"#include "core/mainloop/mainloop.h"#include "core/or/channel.h"#include "core/or/channelpadding.h"#include "core/or/channeltls.h"#include "core/or/circuitbuild.h"#include "core/or/circuitlist.h"#include "core/or/circuitmux.h"#include "core/or/circuitstats.h"#include "core/or/connection_or.h"#include "core/or/dos.h"#include "core/or/relay.h"#include "core/or/scheduler.h"#include "feature/client/entrynodes.h"#include "feature/hs/hs_service.h"#include "feature/nodelist/dirlist.h"#include "feature/nodelist/networkstatus.h"#include "feature/nodelist/nodelist.h"#include "feature/nodelist/routerlist.h"#include "feature/relay/router.h"#include "feature/stats/geoip_stats.h"#include "feature/stats/rephist.h"#include "lib/evloop/timers.h"#include "lib/time/compat_time.h"#include "core/or/cell_queue_st.h"Go to the source code of this file.
Variables | |
| static smartlist_t * | all_channels = NULL |
| static smartlist_t * | active_channels = NULL |
| static smartlist_t * | finished_channels = NULL |
| static smartlist_t * | all_listeners = NULL |
| static smartlist_t * | active_listeners = NULL |
| static smartlist_t * | finished_listeners = NULL |
| static uint64_t | n_channels_allocated = 0 |
| channel_idmap_entry_t | |
OR/OP-to-OR channel abstraction layer. A channel's job is to transfer cells from Tor instance to Tor instance. Currently, there is only one implementation of the channel abstraction: in channeltls.c.
Channels are a higher-level abstraction than or_connection_t: In general, any means that two Tor relays use to exchange cells, or any means that a relay and a client use to exchange cells, is a channel.
Channels differ from pluggable transports in that they do not wrap an underlying protocol over which cells are transmitted: they are the underlying protocol.
This module defines the generic parts of the channel_t interface, and provides the machinery necessary for specialized implementations to be created. At present, there is one specialized implementation in channeltls.c, which uses connection_or.c to send cells over a TLS connection.
Every channel implementation is responsible for being able to transmit cells that are passed to it
For inbound cells, the entry point is: channel_process_cell(). It takes a cell and will pass it to the cell handler set by channel_set_cell_handlers(). Currently, this is passed back to the command subsystem which is command_process_cell().
NOTE: For now, the separation between channels and specialized channels (like channeltls) is not that well defined. So the channeltls layer calls channel_process_cell() which originally comes from the connection subsystem. This should be hopefully be fixed with #23993.
For outbound cells, the entry point is: channel_write_packed_cell(). Only packed cells are dequeued from the circuit queue by the scheduler which uses channel_flush_from_first_active_circuit() to decide which cells to flush from which circuit on the channel. They are then passed down to the channel subsystem. This calls the low layer with the function pointer .write_packed_cell().
Each specialized channel (currently only channeltls_t) MUST implement a series of function found in channel_t. See channel.h for more documentation.
Definition in file channel.c.
| void channel_change_state | ( | channel_t * | chan, |
| channel_state_t | to_state | ||
| ) |
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static |
Change channel state.
This internal and subclass use only function is used to change channel state, performing all transition validity checks and whatever actions are appropriate to the state transition in question.
Definition at line 1519 of file channel.c.
Referenced by channel_change_state(), and channel_change_state_open().
| void channel_change_state_open | ( | channel_t * | chan | ) |
| void channel_check_for_duplicates | ( | void | ) |
Relays run this once an hour to look over our list of channels to other relays. It prints out some statistics if there are multiple connections to many relays.
This function is similar to connection_or_set_bad_connections(), and probably could be adapted to replace it, if it was modified to actually take action on any of these connections.
| void channel_clear_client | ( | channel_t * | chan | ) |
| void channel_clear_identity_digest | ( | channel_t * | chan | ) |
| void channel_clear_remote_end | ( | channel_t * | chan | ) |
| void channel_close_for_error | ( | channel_t * | chan | ) |
Notify that the channel is being closed due to an error condition.
This function is called by the lower layer implementing the transport when a channel must be closed due to an error condition. This does not call the channel's close method, since the lower layer already knows.
| void channel_close_from_lower_layer | ( | channel_t * | chan | ) |
| void channel_closed | ( | channel_t * | chan | ) |
Notify that the lower layer is finished closing the channel.
This function should be called by the lower layer when a channel is finished closing and it should be regarded as inactive and freed by the channel code.
Definition at line 1271 of file channel.c.
Referenced by connection_or_about_to_close().
| channel_t* channel_connect | ( | const tor_addr_t * | addr, |
| uint16_t | port, | ||
| const char * | id_digest, | ||
| const ed25519_public_key_t * | ed_id | ||
| ) |
Connect to a given addr/port/digest.
This sets up a new outgoing channel; in the future if multiple channel_t subclasses are available, this is where the selection policy should go. It may also be desirable to fold port into tor_addr_t or make a new type including a tor_addr_t and port, so we have a single abstract object encapsulating all the protocol details of how to contact an OR.
Definition at line 2319 of file channel.c.
Referenced by channel_connect_for_circuit().
| const char* channel_describe_peer | ( | channel_t * | chan | ) |
| const char* channel_describe_transport | ( | channel_t * | chan | ) |
Describe the transport subclass for a channel.
Invoke a method to get a string description of the lower-layer transport for this channel.
Definition at line 2508 of file channel.c.
Referenced by channel_dump_statistics().
| void channel_do_open_actions | ( | channel_t * | chan | ) |
Take actions required when a channel becomes open.
Handle actions we should do when we know a channel is open; a lot of this comes from the old connection_or_set_state_open() of connection_or.c.
Because of this mechanism, future channel_t subclasses should take care not to change a channel from CHANNEL_STATE_OPENING to CHANNEL_STATE_OPEN until there is positive confirmation that the network is operational. In particular, anything UDP-based should not make this transition until a packet is received from the other side.
Definition at line 1859 of file channel.c.
Referenced by channel_change_state_open().
| void channel_dump_statistics | ( | channel_t * | chan, |
| int | severity | ||
| ) |
| void channel_dump_transport_statistics | ( | channel_t * | chan, |
| int | severity | ||
| ) |
| void channel_dumpstats | ( | int | severity | ) |
Dump channel statistics to the log.
This is called from dumpstats() in main.c and spams the log with statistics on channels.
| channel_t* channel_find_by_global_id | ( | uint64_t | global_identifier | ) |
Find channel by global ID.
This function searches for a channel by the global_identifier assigned at initialization time. This identifier is unique for the lifetime of the Tor process.
Definition at line 650 of file channel.c.
Referenced by circuitmux_set_policy().
| channel_t* channel_find_by_remote_identity | ( | const char * | rsa_id_digest, |
| const ed25519_public_key_t * | ed_id | ||
| ) |
Find channel by RSA/Ed25519 identity of of the remote endpoint.
This function looks up a channel by the digest of its remote endpoint's RSA identity key. If ed_id is provided and nonzero, only a channel matching the ed_id will be returned.
It's possible that more than one channel to a given endpoint exists. Use channel_next_with_rsa_identity() to walk the list of channels; make sure to test for Ed25519 identity match too (as appropriate)
Definition at line 697 of file channel.c.
Referenced by channel_get_for_extend().
| ssize_t channel_flush_some_cells | ( | channel_t * | chan, |
| ssize_t | num_cells | ||
| ) |
Try to flush cells of the given channel chan up to a maximum of num_cells.
This is called by the scheduler when it wants to flush cells from the channel's circuit queue(s) to the connection outbuf (not yet on the wire).
If the channel is not in state CHANNEL_STATE_OPEN, this does nothing and will return 0 meaning no cells were flushed.
If num_cells is -1, we'll try to flush up to the maximum cells allowed defined in MAX_CELLS_TO_GET_FROM_CIRCUITS_FOR_UNLIMITED.
On success, the number of flushed cells are returned and it can never be above num_cells. If 0 is returned, no cells were flushed either because the channel was not opened or we had no cells on the channel. A negative number can NOT be sent back.
This function is part of the fast path.
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Free a channel and skip the state/registration asserts; this internal- use-only function should be called only from channel_free_all() when shutting down the Tor process.
| void channel_free_ | ( | channel_t * | chan | ) |
| void channel_free_all | ( | void | ) |
Close all channels and free everything.
This gets called from tor_free_all() in main.c to clean up on exit. It will close all registered channels and free associated storage, then free the all_channels, active_channels, listening_channels and finished_channels lists and also channel_identity_map.
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Free a list of channels for channel_free_all().
| int channel_get_addr_if_possible | ( | const channel_t * | chan, |
| tor_addr_t * | addr_out | ||
| ) |
Get the remote address for this channel, if possible.
Write the remote address out to a tor_addr_t if the underlying transport supports this operation, and return 1. Return 0 if the underlying transport doesn't let us do this.
Always returns the "real" address of the peer – the one we're connected to on the internet.
Definition at line 2835 of file channel.c.
Referenced by channel_do_open_actions(), and channel_dump_statistics().
| channel_cell_handler_fn_ptr channel_get_cell_handler | ( | channel_t * | chan | ) |
| channel_t* channel_get_for_extend | ( | const char * | rsa_id_digest, |
| const ed25519_public_key_t * | ed_id, | ||
| const tor_addr_t * | target_ipv4_addr, | ||
| const tor_addr_t * | target_ipv6_addr, | ||
| bool | for_origin_circ, | ||
| const char ** | msg_out, | ||
| int * | launch_out | ||
| ) |
Get a channel to extend a circuit.
Given the desired relay identity, pick a suitable channel to extend a circuit to the target IPv4 or IPv6 address requested by the client. Search for an existing channel for the requested endpoint. Make sure the channel is usable for new circuits, and matches one of the target addresses.
Try to return the best channel. But if there is no good channel, set *msg_out to a message describing the channel's state and our next action, and set *launch_out to a boolean indicated whether the caller should try to launch a new channel with channel_connect().
If for_origin_circ is set, mark the channel as interesting for origin circuits, and therefore interesting for our bootstrapping reports.
| int channel_has_queued_writes | ( | channel_t * | chan | ) |
| void channel_init | ( | channel_t * | chan | ) |
Initialize a channel.
This function should be called by subclasses to set up some per-channel variables. I.e., this is the superclass constructor. Before this, the channel should be allocated with tor_malloc_zero().
Definition at line 847 of file channel.c.
Referenced by channel_tls_common_init().
| void channel_init_listener | ( | channel_listener_t * | chan_l | ) |
| int channel_is_bad_for_new_circs | ( | channel_t * | chan | ) |
Check the is_bad_for_new_circs flag.
This function returns the is_bad_for_new_circs flag of the specified channel.
Definition at line 2865 of file channel.c.
Referenced by channel_is_better(), and connection_or_is_bad_for_new_circs().
Decide which of two channels to prefer for extending a circuit.
This function is called while extending a circuit and returns true iff a is 'better' than b. The most important criterion here is that a canonical channel is always better than a non-canonical one, but the number of circuits and the age are used as tie-breakers.
This is based on the former connection_or_is_better() of connection_or.c
| int channel_is_canonical | ( | channel_t * | chan | ) |
Get the canonical flag for a channel.
This returns the is_canonical for a channel; this flag is determined by the lower layer and can't be set in a transport-independent way.
Definition at line 2933 of file channel.c.
Referenced by channel_is_better().
| int channel_is_client | ( | const channel_t * | chan | ) |
Get the client flag.
This returns the client flag of a channel, which will be set if command_process_create_cell() in command.c thinks this is a connection from a client.
Definition at line 2893 of file channel.c.
Referenced by channel_do_open_actions(), and circuit_expire_old_circuits_serverside().
| int channel_is_incoming | ( | channel_t * | chan | ) |
| int channel_is_local | ( | channel_t * | chan | ) |
Test local flag.
This function gets the local flag; the lower layer should set this when setting up the channel if is_local_addr() is true for all of the destinations it will communicate with on behalf of this channel. It's used to decide whether to declare the network reachable when seeing incoming traffic on the channel.
| int channel_is_outgoing | ( | channel_t * | chan | ) |
Test outgoing flag.
This function gets the outgoing flag; this is the inverse of the incoming bit set when a listener spawns a channel. If this returns true the channel was locally initiated.
Definition at line 3025 of file channel.c.
Referenced by channel_do_open_actions(), and channel_set_circid_type().
| void channel_listener_change_state | ( | channel_listener_t * | chan_l, |
| channel_listener_state_t | to_state | ||
| ) |
Change channel listener state.
This internal and subclass use only function is used to change channel listener state, performing all transition validity checks and whatever actions are appropriate to the state transition in question.
Definition at line 1639 of file channel.c.
Referenced by channel_tls_listener_close_method().
| const char* channel_listener_describe_transport | ( | channel_listener_t * | chan_l | ) |
Describe the transport subclass for a channel listener.
Invoke a method to get a string description of the lower-layer transport for this channel listener.
Definition at line 2523 of file channel.c.
Referenced by channel_listener_dump_statistics().
| void channel_listener_dump_statistics | ( | channel_listener_t * | chan_l, |
| int | severity | ||
| ) |
| void channel_listener_dump_transport_statistics | ( | channel_listener_t * | chan_l, |
| int | severity | ||
| ) |
Invoke transport-specific stats dump for channel listener.
If there is a lower-layer statistics dump method, invoke it.
Definition at line 2798 of file channel.c.
Referenced by channel_listener_dump_statistics().
| void channel_listener_dumpstats | ( | int | severity | ) |
Dump channel listener statistics to the log.
This is called from dumpstats() in main.c and spams the log with statistics on channel listeners.
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Free a channel listener and skip the state/registration asserts; this internal-use-only function should be called only from channel_free_all() when shutting down the Tor process.
| void channel_listener_free_ | ( | channel_listener_t * | chan_l | ) |
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Free a list of channel listeners for channel_free_all().
| void channel_listener_mark_for_close | ( | channel_listener_t * | chan_l | ) |
Mark a channel listener for closure.
This function tries to close a channel_listener_t; it will go into the CLOSING state, and eventually the lower layer should put it into the CLOSED or ERROR state. Then, channel_run_cleanup() will eventually free it.
| void channel_listener_process_incoming | ( | channel_listener_t * | listener | ) |
| void channel_listener_queue_incoming | ( | channel_listener_t * | listener, |
| channel_t * | incoming | ||
| ) |
Queue an incoming channel on a listener.
Internal and subclass use only function to queue an incoming channel from a listener. A subclass of channel_listener_t should call this when a new incoming channel is created.
Definition at line 1925 of file channel.c.
Referenced by connection_tls_start_handshake().
| void channel_listener_register | ( | channel_listener_t * | chan_l | ) |
| void channel_listener_run_cleanup | ( | void | ) |
Clean up channel listeners.
This gets called periodically from run_scheduled_events() in main.c; it cleans up after closed channel listeners.
Definition at line 2159 of file channel.c.
Referenced by postloop_cleanup_cb().
| void channel_listener_set_listener_fn | ( | channel_listener_t * | chan_l, |
| channel_listener_fn_ptr | listener | ||
| ) |
Set the listener for a channel listener.
This function sets the handler for new incoming channels on a channel listener.
Definition at line 1062 of file channel.c.
Referenced by command_setup_listener().
| int channel_listener_state_can_transition | ( | channel_listener_state_t | from, |
| channel_listener_state_t | to | ||
| ) |
Indicate whether a channel listener state transition is valid.
This function takes two channel listener states and indicates whether a transition between them is permitted (see the state definitions and transition table in or.h at the channel_listener_state_t typedef).
Definition at line 283 of file channel.c.
Referenced by channel_listener_change_state().
| int channel_listener_state_is_valid | ( | channel_listener_state_t | state | ) |
Indicate whether a given channel listener state is valid.
Definition at line 210 of file channel.c.
Referenced by channel_listener_change_state().
| const char* channel_listener_state_to_string | ( | channel_listener_state_t | state | ) |
Return a human-readable description for a channel listener state.
Definition at line 350 of file channel.c.
Referenced by channel_listener_dump_statistics().
| void channel_listener_timestamp_accepted | ( | channel_listener_t * | chan_l | ) |
| void channel_listener_timestamp_active | ( | channel_listener_t * | chan_l | ) |
| void channel_listener_timestamp_created | ( | channel_listener_t * | chan_l | ) |
Update the created timestamp for a channel listener.
This updates the channel listener's created timestamp and should only be called from channel_init_listener().
| void channel_listener_unregister | ( | channel_listener_t * | chan_l | ) |
| void channel_mark_bad_for_new_circs | ( | channel_t * | chan | ) |
| void channel_mark_client | ( | channel_t * | chan | ) |
| void channel_mark_for_close | ( | channel_t * | chan | ) |
Mark a channel for closure.
This function tries to close a channel_t; it will go into the CLOSING state, and eventually the lower layer should put it into the CLOSED or ERROR state. Then, channel_run_cleanup() will eventually free it.
Definition at line 1137 of file channel.c.
Referenced by channel_flush_from_first_active_circuit(), and channel_tls_listener_close_method().
| void channel_mark_incoming | ( | channel_t * | chan | ) |
| void channel_mark_local | ( | channel_t * | chan | ) |
Set the local flag.
This internal-only function should be called by the lower layer if the channel is to a local address. See channel_is_local() above or the description of the is_local bit in channel.h.
| void channel_mark_outgoing | ( | channel_t * | chan | ) |
| void channel_mark_remote | ( | channel_t * | chan | ) |
Mark a channel as remote.
This internal-only function should be called by the lower layer if the channel is not to a local address but has previously been marked local. See channel_is_local() above or the description of the is_local bit in channel.h
| int channel_matches_extend_info | ( | channel_t * | chan, |
| extend_info_t * | extend_info | ||
| ) |
Check if a channel matches an extend_info_t.
This function calls the lower layer and asks if this channel matches a given extend_info_t.
NOTE that this function only checks for an address/port match, and should be used only when no identity is available.
Definition at line 3270 of file channel.c.
Referenced by circuit_get_all_pending_on_channel().
| STATIC bool channel_matches_target_addr_for_extend | ( | channel_t * | chan, |
| const tor_addr_t * | target_ipv4_addr, | ||
| const tor_addr_t * | target_ipv6_addr | ||
| ) |
Check if a channel matches the given target IPv4 or IPv6 addresses. If either address matches, return true. If neither address matches, return false.
Both addresses can't be NULL.
This function calls into the lower layer and asks if this channel thinks it matches the target addresses for circuit extension purposes.
| int channel_more_to_flush | ( | channel_t * | chan | ) |
Get next channel with digest.
This function takes a channel and finds the next channel in the list with the same digest.
Definition at line 731 of file channel.c.
Referenced by channel_get_for_extend().
| void channel_notify_flushed | ( | channel_t * | chan | ) |
| int channel_num_cells_writeable | ( | channel_t * | chan | ) |
| unsigned int channel_num_circuits | ( | channel_t * | chan | ) |
Return the total number of circuits used by a channel.
| chan | Channel to query |
Definition at line 3316 of file channel.c.
Referenced by channel_is_better(), and connection_or_get_num_circuits().
| void channel_register | ( | channel_t * | chan | ) |
| int channel_remote_identity_matches | ( | const channel_t * | chan, |
| const char * | rsa_id_digest, | ||
| const ed25519_public_key_t * | ed_id | ||
| ) |
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Helper for channel_update_bad_for_new_circs(): Perform the channel_update_bad_for_new_circs operation on all channels in lst, all of which MUST have the same RSA ID. (They MAY have different Ed25519 IDs.)
| void channel_run_cleanup | ( | void | ) |
Clean up channels.
This gets called periodically from run_scheduled_events() in main.c; it cleans up after closed channels.
Definition at line 2133 of file channel.c.
Referenced by postloop_cleanup_cb().
| void channel_set_cell_handlers | ( | channel_t * | chan, |
| channel_cell_handler_fn_ptr | cell_handler | ||
| ) |
Set both cell handlers for a channel.
This function sets both the fixed-length and variable length cell handlers for a channel.
Definition at line 1102 of file channel.c.
Referenced by command_setup_channel().
| void channel_set_circid_type | ( | channel_t * | chan, |
| crypto_pk_t * | identity_rcvd, | ||
| int | consider_identity | ||
| ) |
| void channel_set_identity_digest | ( | channel_t * | chan, |
| const char * | identity_digest, | ||
| const ed25519_public_key_t * | ed_identity | ||
| ) |
| int channel_state_can_transition | ( | channel_state_t | from, |
| channel_state_t | to | ||
| ) |
Indicate whether a channel state transition is valid.
This function takes two channel states and indicates whether a transition between them is permitted (see the state definitions and transition table in or.h at the channel_state_t typedef).
Definition at line 237 of file channel.c.
Referenced by channel_change_state_().
| int channel_state_is_valid | ( | channel_state_t | state | ) |
Indicate whether a given channel state is valid.
Definition at line 185 of file channel.c.
Referenced by channel_change_state_().
| const char* channel_state_to_string | ( | channel_state_t | state | ) |
Return a human-readable description for a channel state.
Definition at line 315 of file channel.c.
Referenced by channel_dump_statistics().
| void channel_timestamp_active | ( | channel_t * | chan | ) |
Update the last active timestamp for a channel.
This function updates the channel's last active timestamp; it should be called by the lower layer whenever there is activity on the channel which does not lead to a cell being transmitted or received; the active timestamp is also updated from channel_timestamp_recv() and channel_timestamp_xmit(), but it should be updated for things like the v3 handshake and stuff that produce activity only visible to the lower layer.
Definition at line 3122 of file channel.c.
Referenced by connection_or_flushed_some().
| void channel_timestamp_client | ( | channel_t * | chan | ) |
| void channel_timestamp_created | ( | channel_t * | chan | ) |
Update the created timestamp for a channel.
This updates the channel's created timestamp and should only be called from channel_init().
| void channel_timestamp_recv | ( | channel_t * | chan | ) |
| void channel_timestamp_xmit | ( | channel_t * | chan | ) |
| void channel_unregister | ( | channel_t * | chan | ) |
| void channel_update_bad_for_new_circs | ( | const char * | digest, |
| int | force | ||
| ) |
Go through all the channels (or if digest is non-NULL, just the OR connections with that digest), and set the is_bad_for_new_circs flag based on the rules in connection_or_group_set_badness() (or just always set it if force is true).
Definition at line 3438 of file channel.c.
Referenced by second_elapsed_callback().
| time_t channel_when_created | ( | channel_t * | chan | ) |
Query created timestamp for a channel.
Definition at line 3231 of file channel.c.
Referenced by channel_is_better().
| time_t channel_when_last_client | ( | channel_t * | chan | ) |
Query client timestamp.
Definition at line 3242 of file channel.c.
Referenced by connection_or_client_used().
| time_t channel_when_last_xmit | ( | channel_t * | chan | ) |
Query xmit timestamp.
Definition at line 3253 of file channel.c.
Referenced by circuit_expire_old_circuits_serverside().
| int channel_write_packed_cell | ( | channel_t * | chan, |
| packed_cell_t * | cell | ||
| ) |
Write a packed cell to a channel.
Write a packed cell to a channel using the write_cell() method. This is called by the transport-independent code to deliver a packed cell to a channel for transmission.
Return 0 on success else a negative value. In both cases, the caller should not access the cell anymore, it is freed both on success and error.
Definition at line 1484 of file channel.c.
Referenced by channel_flush_from_first_active_circuit().
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| int packed_cell_is_destroy | ( | channel_t * | chan, |
| const packed_cell_t * | packed_cell, | ||
| circid_t * | circid_out | ||
| ) |
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1.9.1