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Diffstat (limited to 'src/or/circuit_st.h')
| -rw-r--r-- | src/or/circuit_st.h | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/src/or/circuit_st.h b/src/or/circuit_st.h new file mode 100644 index 0000000000..f977d542dd --- /dev/null +++ b/src/or/circuit_st.h @@ -0,0 +1,172 @@ +/* Copyright (c) 2001 Matej Pfajfar. + * Copyright (c) 2001-2004, Roger Dingledine. + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2017, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +#ifndef CIRCUIT_ST_H +#define CIRCUIT_ST_H + +#include "or.h" + +#include "cell_queue_st.h" + +/** + * 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. + */ +struct circuit_t { + uint32_t magic; /**< For memory and type debugging: must equal + * ORIGIN_CIRCUIT_MAGIC or OR_CIRCUIT_MAGIC. */ + + /** The channel that is next in this circuit. */ + channel_t *n_chan; + + /** + * 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) + */ + circid_t n_circ_id; + + /** + * Circuit mux associated with n_chan to which this circuit is attached; + * NULL if we have no n_chan. + */ + circuitmux_t *n_mux; + + /** Queue of cells waiting to be transmitted on n_chan */ + cell_queue_t n_chan_cells; + + /** + * The hop to which we want to extend this circuit. Should be NULL if + * the circuit has attached to a channel. + */ + extend_info_t *n_hop; + + /** 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.) */ + unsigned int streams_blocked_on_n_chan : 1; + /** 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.) */ + unsigned int streams_blocked_on_p_chan : 1; + + /** True iff we have queued a delete backwards on this circuit, but not put + * it on the output buffer. */ + unsigned int p_delete_pending : 1; + /** True iff we have queued a delete forwards on this circuit, but not put + * it on the output buffer. */ + unsigned int n_delete_pending : 1; + + /** True iff this circuit has received a DESTROY cell in either direction */ + unsigned int received_destroy : 1; + + uint8_t state; /**< Current status of this circuit. */ + uint8_t purpose; /**< Why are we creating this circuit? */ + + /** 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? */ + int package_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. */ + int deliver_window; + + /** Temporary field used during circuits_handle_oom. */ + uint32_t age_tmp; + + /** For storage while n_chan is pending (state CIRCUIT_STATE_CHAN_WAIT). */ + struct create_cell_t *n_chan_create_cell; + + /** 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. + */ + struct timeval timestamp_began; + + /** This timestamp marks when the init_circuit_base constructor ran. */ + struct timeval timestamp_created; + + /** 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. + */ + time_t timestamp_dirty; + + 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.) */ + const char *marked_for_close_file; /**< For debugging: in which file was this + * circuit marked for close? */ + /** 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. */ + int marked_for_close_reason; + /** As marked_for_close_reason, but reflects the underlying reason for + * closing this circuit. + */ + int marked_for_close_orig_reason; + + /** Unique ID for measuring tunneled network status requests. */ + uint64_t dirreq_id; + + /** Index in smartlist of all circuits (global_circuitlist). */ + int global_circuitlist_idx; + + /** 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. */ + smartlist_t *testing_cell_stats; + + /** If set, points to an HS token that this circuit might be carrying. + * Used by the HS circuitmap. */ + hs_token_t *hs_token; + /** Hashtable node: used to look up the circuit by its HS token using the HS + circuitmap. */ + HT_ENTRY(circuit_t) hs_circuitmap_node; +}; + +#endif + |