Tor  0.4.3.0-alpha-dev
circuit_st.h
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1 /* Copyright (c) 2001 Matej Pfajfar.
2  * Copyright (c) 2001-2004, Roger Dingledine.
3  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
4  * Copyright (c) 2007-2019, The Tor Project, Inc. */
5 /* See LICENSE for licensing information */
6 
7 /**
8  * @file circuit_st.h
9  * @brief Base circuit structure.
10  **/
11 
12 #ifndef CIRCUIT_ST_H
13 #define CIRCUIT_ST_H
14 
15 #include "core/or/or.h"
16 
17 #include "lib/container/handles.h"
18 
19 #include "core/or/cell_queue_st.h"
20 
21 struct hs_token_t;
24 
25 /** Number of padding state machines on a circuit. */
26 #define CIRCPAD_MAX_MACHINES (2)
27 
28 /** "magic" value for an origin_circuit_t */
29 #define ORIGIN_CIRCUIT_MAGIC 0x35315243u
30 /** "magic" value for an or_circuit_t */
31 #define OR_CIRCUIT_MAGIC 0x98ABC04Fu
32 /** "magic" value for a circuit that would have been freed by circuit_free,
33  * but which we're keeping around until a cpuworker reply arrives. See
34  * circuit_free() for more documentation. */
35 #define DEAD_CIRCUIT_MAGIC 0xdeadc14c
36 
37 /**
38  * A circuit is a path over the onion routing
39  * network. Applications can connect to one end of the circuit, and can
40  * create exit connections at the other end of the circuit. AP and exit
41  * connections have only one circuit associated with them (and thus these
42  * connection types are closed when the circuit is closed), whereas
43  * OR connections multiplex many circuits at once, and stay standing even
44  * when there are no circuits running over them.
45  *
46  * A circuit_t structure can fill one of two roles. First, a or_circuit_t
47  * links two connections together: either an edge connection and an OR
48  * connection, or two OR connections. (When joined to an OR connection, a
49  * circuit_t affects only cells sent to a particular circID on that
50  * connection. When joined to an edge connection, a circuit_t affects all
51  * data.)
52 
53  * Second, an origin_circuit_t holds the cipher keys and state for sending data
54  * along a given circuit. At the OP, it has a sequence of ciphers, each
55  * of which is shared with a single OR along the circuit. Separate
56  * ciphers are used for data going "forward" (away from the OP) and
57  * "backward" (towards the OP). At the OR, a circuit has only two stream
58  * ciphers: one for data going forward, and one for data going backward.
59  */
60 struct circuit_t {
61  uint32_t magic; /**< For memory and type debugging: must equal
62  * ORIGIN_CIRCUIT_MAGIC or OR_CIRCUIT_MAGIC. */
63 
64  /** Handle entry for handle-based lookup */
65  HANDLE_ENTRY(circuit, circuit_t);
66 
67  /** The channel that is next in this circuit. */
68  channel_t *n_chan;
69 
70  /**
71  * The circuit_id used in the next (forward) hop of this circuit;
72  * this is unique to n_chan, but this ordered pair is globally
73  * unique:
74  *
75  * (n_chan->global_identifier, n_circ_id)
76  */
78 
79  /** Queue of cells waiting to be transmitted on n_chan */
81 
82  /**
83  * The hop to which we want to extend this circuit. Should be NULL if
84  * the circuit has attached to a channel.
85  */
87 
88  /** True iff we are waiting for n_chan_cells to become less full before
89  * allowing p_streams to add any more cells. (Origin circuit only.) */
90  unsigned int streams_blocked_on_n_chan : 1;
91  /** True iff we are waiting for p_chan_cells to become less full before
92  * allowing n_streams to add any more cells. (OR circuit only.) */
93  unsigned int streams_blocked_on_p_chan : 1;
94 
95  /** True iff we have queued a delete backwards on this circuit, but not put
96  * it on the output buffer. */
97  unsigned int p_delete_pending : 1;
98  /** True iff we have queued a delete forwards on this circuit, but not put
99  * it on the output buffer. */
100  unsigned int n_delete_pending : 1;
101 
102  /** True iff this circuit has received a DESTROY cell in either direction */
103  unsigned int received_destroy : 1;
104 
105  /** True iff we have sent a sufficiently random data cell since last
106  * we reset send_randomness_after_n_cells. */
108 
109  uint8_t state; /**< Current status of this circuit. */
110  uint8_t purpose; /**< Why are we creating this circuit? */
111 
112  /** How many relay data cells can we package (read from edge streams)
113  * on this circuit before we receive a circuit-level sendme cell asking
114  * for more? */
116  /** How many relay data cells will we deliver (write to edge streams)
117  * on this circuit? When deliver_window gets low, we send some
118  * circuit-level sendme cells to indicate that we're willing to accept
119  * more. */
121  /**
122  * How many cells do we have until we need to send one that contains
123  * sufficient randomness? Used to ensure that authenticated SENDME cells
124  * will reflect some unpredictable information.
125  **/
127 
128  /** FIFO containing the digest of the cells that are just before a SENDME is
129  * sent by the client. It is done at the last cell before our package_window
130  * goes down to 0 which is when we expect a SENDME.
131  *
132  * Our current circuit package window is capped to 1000
133  * (CIRCWINDOW_START_MAX) which is also the start value. The increment is
134  * set to 100 (CIRCWINDOW_INCREMENT) which means we don't allow more than
135  * 1000/100 = 10 outstanding SENDME cells worth of data. Meaning that this
136  * list can not contain more than 10 digests of DIGEST_LEN bytes (20).
137  *
138  * At position i in the list, the digest corresponds to the
139  * (CIRCWINDOW_INCREMENT * i)-nth cell received since we expect a SENDME to
140  * be received containing that cell digest.
141  *
142  * For example, position 2 (starting at 0) means that we've received 300
143  * cells so the 300th cell digest is kept at index 2.
144  *
145  * At maximum, this list contains 200 bytes plus the smartlist overhead. */
147 
148  /** Temporary field used during circuits_handle_oom. */
149  uint32_t age_tmp;
150 
151  /** For storage while n_chan is pending (state CIRCUIT_STATE_CHAN_WAIT). */
153 
154  /** When did circuit construction actually begin (ie send the
155  * CREATE cell or begin cannibalization).
156  *
157  * Note: This timer will get reset if we decide to cannibalize
158  * a circuit. It may also get reset during certain phases of hidden
159  * service circuit use.
160  *
161  * We keep this timestamp with a higher resolution than most so that the
162  * circuit-build-time tracking code can get millisecond resolution.
163  */
165 
166  /** This timestamp marks when the init_circuit_base constructor ran. */
168 
169  /** When the circuit was first used, or 0 if the circuit is clean.
170  *
171  * XXXX Note that some code will artificially adjust this value backward
172  * in time in order to indicate that a circuit shouldn't be used for new
173  * streams, but that it can stay alive as long as it has streams on it.
174  * That's a kludge we should fix.
175  *
176  * XXX The CBT code uses this field to record when HS-related
177  * circuits entered certain states. This usage probably won't
178  * interfere with this field's primary purpose, but we should
179  * document it more thoroughly to make sure of that.
180  *
181  * XXX The SocksPort option KeepaliveIsolateSOCKSAuth will artificially
182  * adjust this value forward each time a suitable stream is attached to an
183  * already constructed circuit, potentially keeping the circuit alive
184  * indefinitely.
185  */
187 
188  uint16_t marked_for_close; /**< Should we close this circuit at the end of
189  * the main loop? (If true, holds the line number
190  * where this circuit was marked.) */
191  const char *marked_for_close_file; /**< For debugging: in which file was this
192  * circuit marked for close? */
193  /** For what reason (See END_CIRC_REASON...) is this circuit being closed?
194  * This field is set in circuit_mark_for_close and used later in
195  * circuit_about_to_free. */
197  /** As marked_for_close_reason, but reflects the underlying reason for
198  * closing this circuit.
199  */
201 
202  /** Unique ID for measuring tunneled network status requests. */
203  uint64_t dirreq_id;
204 
205  /** Index in smartlist of all circuits (global_circuitlist). */
207 
208  /** Various statistics about cells being added to or removed from this
209  * circuit's queues; used only if CELL_STATS events are enabled and
210  * cleared after being sent to control port. */
212 
213  /** If set, points to an HS token that this circuit might be carrying.
214  * Used by the HS circuitmap. */
215  struct hs_token_t *hs_token;
216  /** Hashtable node: used to look up the circuit by its HS token using the HS
217  circuitmap. */
218  HT_ENTRY(circuit_t) hs_circuitmap_node;
219 
220  /** Adaptive Padding state machines: these are immutable. The state machines
221  * that come from the consensus are saved to a global structure, to avoid
222  * per-circuit allocations. This merely points to the global copy in
223  * origin_padding_machines or relay_padding_machines that should never
224  * change or get deallocated.
225  *
226  * Each element of this array corresponds to a different padding machine,
227  * and we can have up to CIRCPAD_MAX_MACHINES such machines. */
229 
230  /** Adaptive Padding machine runtime info for above machines. This is
231  * the per-circuit mutable information, such as the current state and
232  * histogram token counts. Some of it is optional (aka NULL).
233  * If a machine is being shut down, these indexes can be NULL
234  * without the corresponding padding_machine being NULL, while we
235  * wait for the other end to respond to our shutdown request.
236  *
237  * Each element of this array corresponds to a different padding machine,
238  * and we can have up to CIRCPAD_MAX_MACHINES such machines. */
240 };
241 
242 #endif /* !defined(CIRCUIT_ST_H) */
#define CIRCPAD_MAX_MACHINES
Definition: circuit_st.h:26
Cell queue structures.
channel_t * n_chan
Definition: circuit_st.h:68
smartlist_t * testing_cell_stats
Definition: circuit_st.h:211
const struct circpad_machine_spec_t * padding_machine[CIRCPAD_MAX_MACHINES]
Definition: circuit_st.h:228
HANDLE_ENTRY(circuit, circuit_t)
int marked_for_close_orig_reason
Definition: circuit_st.h:200
unsigned int received_destroy
Definition: circuit_st.h:103
uint32_t magic
Definition: circuit_st.h:61
extend_info_t * n_hop
Definition: circuit_st.h:86
int deliver_window
Definition: circuit_st.h:120
uint8_t state
Definition: circuit_st.h:109
uint8_t purpose
Definition: circuit_st.h:110
unsigned int streams_blocked_on_n_chan
Definition: circuit_st.h:90
Macros for C weak-handle implementation.
struct timeval timestamp_began
Definition: circuit_st.h:164
struct circpad_machine_runtime_t * padding_info[CIRCPAD_MAX_MACHINES]
Definition: circuit_st.h:239
uint16_t marked_for_close
Definition: circuit_st.h:188
struct timeval timestamp_created
Definition: circuit_st.h:167
unsigned int have_sent_sufficiently_random_cell
Definition: circuit_st.h:107
struct create_cell_t * n_chan_create_cell
Definition: circuit_st.h:152
int marked_for_close_reason
Definition: circuit_st.h:196
Master header file for Tor-specific functionality.
unsigned int n_delete_pending
Definition: circuit_st.h:100
int global_circuitlist_idx
Definition: circuit_st.h:206
unsigned int streams_blocked_on_p_chan
Definition: circuit_st.h:93
struct hs_token_t * hs_token
Definition: circuit_st.h:215
uint16_t send_randomness_after_n_cells
Definition: circuit_st.h:126
uint32_t age_tmp
Definition: circuit_st.h:149
HT_ENTRY(circuit_t) hs_circuitmap_node
int package_window
Definition: circuit_st.h:115
uint64_t dirreq_id
Definition: circuit_st.h:203
smartlist_t * sendme_last_digests
Definition: circuit_st.h:146
uint32_t circid_t
Definition: or.h:608
time_t timestamp_dirty
Definition: circuit_st.h:186
unsigned int p_delete_pending
Definition: circuit_st.h:97
circid_t n_circ_id
Definition: circuit_st.h:77
cell_queue_t n_chan_cells
Definition: circuit_st.h:80
const char * marked_for_close_file
Definition: circuit_st.h:191