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
|
/* Copyright (c) 2019-2021, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file conflux_st.h
* \brief Structure definitions for conflux multipath
**/
#ifndef CONFLUX_ST_H
#define CONFLUX_ST_H
#include "core/or/circuit_st.h"
#include "core/or/cell_st.h"
#include "lib/defs/digest_sizes.h"
/**
* Specifies which conflux alg is in use.
*/
typedef enum {
CONFLUX_ALG_MINRTT = 0,
CONFLUX_ALG_LOWRTT = 1,
CONFLUX_ALG_CWNDRTT = 2,
} conflux_alg_t;
/**
* Maximum number of linked circuits.
*
* We want to experiment with 3 guards, so we need at least 3 here.
*
* However, we need 1 more than this, to support using a test circuit to probe
* for a faster path, for applications that *require* a specific latency target
* (like VoIP).
*
* We may also want to raise this for traffic analysis defense evaluation.
*/
#define CONFLUX_MAX_CIRCS 4
/** XXX: Cached consensus params+scheduling alg */
struct conflux_params_t {
conflux_alg_t alg;
};
struct conflux_leg_t {
/**
* For computing ooo_q insertion sequence numbers: Highest absolute
* sequence number received on each leg, before delivery.
*
* As a receiver, this allows us to compute the absolute sequence number
* of a cell for delivery or insertion into the ooo_q. When a SWITCH cell
* is received on a leg, the absolute sequence number of that cell is
* the relative sequence number in that cell, plus the absolute sequence
* number of that leg from this array. The leg's sequence number
* is then updated to this value immediately.
*
* In this way, we are able to assign absolute sequence numbers to cells
* immediately, regardless of how many legs or leg switches have occurred,
* and regardless of the delivery status of each cell versus if it must be
* queued.
*/
uint64_t last_seq_recv;
/**
* For relative sequencing: Highest absolute sequence number sent on each
* circuit. The overall absolute current sent sequence number is the highest
* of these values.
*
* As a sender, this allows us to compute a relative sequence number when
* switching legs. When switching legs, the sender looks up its current
* absolute sequence number as the maximum of all legs. The sender then
* compares that to the current sequence number on the leg it is about to
* send on, and then computes the relative sequence number as the difference
* between the overall absolute sequence number and the sequence number
* from the sending leg.
*
* In this way, we can use much smaller relative sequence numbers on the
* wire, as opposed to larger absolute values, at the expense of this
* bookkeeping overhead on each end.
*/
uint64_t last_seq_sent;
/**
* Current round-trip of the circuit, in usec.
*
* XXX: In theory, we could use the congestion control RTTs directly off the
* circs, but congestion control code has assumptions about the RTT being 0
* at the start of the circuit, which will *not* be the case here, because we
* get an RTT off the link circuit. */
uint64_t circ_rtts_usec;
/** Exit side only: When was the LINKED cell sent? Used for RTT measurement
* that sets circ_rtts_usec when the LINKED_ACK is received. */
uint64_t linked_sent_usec;
/** Circuit of this leg. */
circuit_t *circ;
};
/** Fields for conflux multipath support */
struct conflux_t {
/** Cached parameters for this circuit */
struct conflux_params_t params;
/**
* List of all linked conflux_leg_t for this set. Once a leg is in that list,
* it can be used to transmit data. */
smartlist_t *legs;
/**
* Out-of-order priority queue of conflux_cell_t *, heapified
* on conflux_cell_t.seq number (lowest at top of heap).
*
* XXX: We are most likely to insert cells at either the head or the tail.
* Verify that is fast-path wrt smartlist priority queues, and not a memmove
* nightmare. If so, we may need a real linked list, or a packed_cell_t list.
*/
smartlist_t *ooo_q;
/**
* Absolute sequence number of cells delivered to streams since start.
* (ie: this is updated *after* dequeue from the ooo_q priority queue). */
uint64_t last_seq_delivered;
/**
* The estimated remaining number of cells we can send on this circuit
* before we are allowed to switch legs. */
uint64_t cells_until_switch;
/** Current circuit leg. Only use this with conflux_get_circ_for_leg() for
* bounds checking. */
struct conflux_leg_t *curr_leg;
/** Previous circuit leg. Only use this with conflux_get_circ_for_leg() for
* bounds checking. */
struct conflux_leg_t *prev_leg;
/** The nonce that joins these */
uint8_t nonce[DIGEST256_LEN];
/** Indicate if this conflux set is in full teardown. We mark it at the first
* close in case of a total teardown so we avoid recursive calls of circuit
* mark for close. */
bool in_full_teardown;
/** Number of leg launch that we've done for this set. We keep this value
* because there is a maximum allowed in order to avoid side channel(s). */
unsigned int num_leg_launch;
/**
* PolicyHint: Predicted ports/protocol shorthand..
*
* XXX: This might be redundant to the circuit's exitpolicy.
*/
};
#endif /* !defined(CONFLUX_ST_H) */
|
