#include <or.h>
Public Member Functions | |
| HT_ENTRY (circuit_t) hs_circuitmap_node | |
Data Fields | |
| uint32_t | magic |
| channel_t * | n_chan |
| circid_t | n_circ_id |
| circuitmux_t * | n_mux |
| cell_queue_t | n_chan_cells |
| extend_info_t * | n_hop |
| unsigned int | streams_blocked_on_n_chan: 1 |
| unsigned int | streams_blocked_on_p_chan: 1 |
| unsigned int | p_delete_pending: 1 |
| unsigned int | n_delete_pending: 1 |
| unsigned int | received_destroy: 1 |
| uint8_t | state |
| uint8_t | purpose |
| int | package_window |
| int | deliver_window |
| uint32_t | age_tmp |
| struct create_cell_t * | n_chan_create_cell |
| struct timeval | timestamp_began |
| struct timeval | timestamp_created |
| time_t | timestamp_dirty |
| uint16_t | marked_for_close |
| const char * | marked_for_close_file |
| int | marked_for_close_reason |
| int | marked_for_close_orig_reason |
| uint64_t | dirreq_id |
| int | global_circuitlist_idx |
| smartlist_t * | testing_cell_stats |
| hs_token_t * | hs_token |
Detailed Description
A circuit is a path over the onion routing network. Applications can connect to one end of the circuit, and can create exit connections at the other end of the circuit. AP and exit connections have only one circuit associated with them (and thus these connection types are closed when the circuit is closed), whereas OR connections multiplex many circuits at once, and stay standing even when there are no circuits running over them.
A circuit_t structure can fill one of two roles. First, a or_circuit_t links two connections together: either an edge connection and an OR connection, or two OR connections. (When joined to an OR connection, a circuit_t affects only cells sent to a particular circID on that connection. When joined to an edge connection, a circuit_t affects all data.)
Second, an origin_circuit_t holds the cipher keys and state for sending data along a given circuit. At the OP, it has a sequence of ciphers, each of which is shared with a single OR along the circuit. Separate ciphers are used for data going "forward" (away from the OP) and "backward" (towards the OP). At the OR, a circuit has only two stream ciphers: one for data going forward, and one for data going backward.
Member Function Documentation
◆ HT_ENTRY()
| HT_ENTRY | ( | circuit_t | ) |
Hashtable node: used to look up the circuit by its HS token using the HS circuitmap.
Field Documentation
◆ age_tmp
| uint32_t age_tmp |
Temporary field used during circuits_handle_oom.
◆ deliver_window
| int deliver_window |
How many relay data cells will we deliver (write to edge streams) on this circuit? When deliver_window gets low, we send some circuit-level sendme cells to indicate that we're willing to accept more.
◆ dirreq_id
| uint64_t dirreq_id |
Unique ID for measuring tunneled network status requests.
◆ global_circuitlist_idx
| int global_circuitlist_idx |
Index in smartlist of all circuits (global_circuitlist).
◆ hs_token
| hs_token_t* hs_token |
If set, points to an HS token that this circuit might be carrying. Used by the HS circuitmap.
◆ magic
| uint32_t magic |
For memory and type debugging: must equal ORIGIN_CIRCUIT_MAGIC or OR_CIRCUIT_MAGIC.
◆ marked_for_close
| uint16_t marked_for_close |
Should we close this circuit at the end of the main loop? (If true, holds the line number where this circuit was marked.)
◆ marked_for_close_file
| const char* marked_for_close_file |
For debugging: in which file was this circuit marked for close?
◆ marked_for_close_orig_reason
| int marked_for_close_orig_reason |
As marked_for_close_reason, but reflects the underlying reason for closing this circuit.
◆ marked_for_close_reason
| int marked_for_close_reason |
For what reason (See END_CIRC_REASON...) is this circuit being closed? This field is set in circuit_mark_for_close and used later in circuit_about_to_free.
◆ n_chan
| channel_t* n_chan |
The channel that is next in this circuit.
◆ n_chan_cells
| cell_queue_t n_chan_cells |
Queue of cells waiting to be transmitted on n_chan
◆ n_chan_create_cell
| struct create_cell_t* n_chan_create_cell |
For storage while n_chan is pending (state CIRCUIT_STATE_CHAN_WAIT).
◆ n_circ_id
| circid_t n_circ_id |
The circuit_id used in the next (forward) hop of this circuit; this is unique to n_chan, but this ordered pair is globally unique:
(n_chan->global_identifier, n_circ_id)
◆ n_delete_pending
| unsigned int n_delete_pending |
True iff we have queued a delete forwards on this circuit, but not put it on the output buffer.
◆ n_hop
| extend_info_t* n_hop |
The hop to which we want to extend this circuit. Should be NULL if the circuit has attached to a channel.
◆ n_mux
| circuitmux_t* n_mux |
Circuit mux associated with n_chan to which this circuit is attached; NULL if we have no n_chan.
◆ p_delete_pending
| unsigned int p_delete_pending |
True iff we have queued a delete backwards on this circuit, but not put it on the output buffer.
◆ package_window
| int package_window |
How many relay data cells can we package (read from edge streams) on this circuit before we receive a circuit-level sendme cell asking for more?
◆ purpose
| uint8_t purpose |
Why are we creating this circuit?
◆ received_destroy
| unsigned int received_destroy |
True iff this circuit has received a DESTROY cell in either direction
◆ state
| uint8_t state |
Current status of this circuit.
◆ streams_blocked_on_n_chan
| unsigned int streams_blocked_on_n_chan |
True iff we are waiting for n_chan_cells to become less full before allowing p_streams to add any more cells. (Origin circuit only.)
◆ streams_blocked_on_p_chan
| unsigned int streams_blocked_on_p_chan |
True iff we are waiting for p_chan_cells to become less full before allowing n_streams to add any more cells. (OR circuit only.)
◆ testing_cell_stats
| smartlist_t* testing_cell_stats |
Various statistics about cells being added to or removed from this circuit's queues; used only if CELL_STATS events are enabled and cleared after being sent to control port.
◆ timestamp_began
| struct timeval timestamp_began |
When did circuit construction actually begin (ie send the CREATE cell or begin cannibalization).
Note: This timer will get reset if we decide to cannibalize a circuit. It may also get reset during certain phases of hidden service circuit use.
We keep this timestamp with a higher resolution than most so that the circuit-build-time tracking code can get millisecond resolution.
◆ timestamp_created
| struct timeval timestamp_created |
This timestamp marks when the init_circuit_base constructor ran.
◆ timestamp_dirty
| time_t timestamp_dirty |
When the circuit was first used, or 0 if the circuit is clean.
XXXX Note that some code will artificially adjust this value backward in time in order to indicate that a circuit shouldn't be used for new streams, but that it can stay alive as long as it has streams on it. That's a kludge we should fix.
XXX The CBT code uses this field to record when HS-related circuits entered certain states. This usage probably won't interfere with this field's primary purpose, but we should document it more thoroughly to make sure of that.
XXX The SocksPort option KeepaliveIsolateSOCKSAuth will artificially adjust this value forward each time a suitable stream is attached to an already constructed circuit, potentially keeping the circuit alive indefinitely.
The documentation for this struct was generated from the following file:
- /home/user/_my/code/bwauth-related/tor/src/or/or.h
