1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#ifndef CIRCUIT_ST_H
#define CIRCUIT_ST_H
#include "core/or/or.h"
#include "core/or/cell_queue_st.h"
struct hs_token_t;
/** "magic" value for an origin_circuit_t */
#define ORIGIN_CIRCUIT_MAGIC 0x35315243u
/** "magic" value for an or_circuit_t */
#define OR_CIRCUIT_MAGIC 0x98ABC04Fu
/** "magic" value for a circuit that would have been freed by circuit_free,
* but which we're keeping around until a cpuworker reply arrives. See
* circuit_free() for more documentation. */
#define DEAD_CIRCUIT_MAGIC 0xdeadc14c
/**
* 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. */
struct 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
|
