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
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
content / browser / webtransport / web_transport_throttle_context.cc [blame]
// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/webtransport/web_transport_throttle_context.h"
#include "base/check.h"
#include "base/check_op.h"
#include "base/command_line.h"
#include "base/functional/callback.h"
#include "base/logging.h"
#include "base/rand_util.h"
#include "components/network_session_configurator/common/network_switches.h"
namespace content {
namespace {
bool ShouldQueueHandshakeFailurePenalty() {
base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
return !command_line ||
!command_line->HasSwitch(switches::kWebTransportDeveloperMode);
}
} // namespace
WebTransportThrottleContext::PenaltyManager::PenaltyManager(
WebTransportThrottleContext* throttle_context)
: throttle_context_(throttle_context) {}
WebTransportThrottleContext::PenaltyManager::~PenaltyManager() = default;
void WebTransportThrottleContext::PenaltyManager::QueuePending(
base::TimeDelta after) {
DVLOG(1) << "WebTransportThrottleContext::QueuePending() this=" << this
<< " after=" << after
<< " pending_handshakes_= " << pending_handshakes_;
const auto when = base::TimeTicks::Now() + after;
if (pending_queue_.empty() || when < pending_queue_.top()) {
StartPendingQueueTimer(after);
}
pending_queue_.push(when);
}
void WebTransportThrottleContext::PenaltyManager::MaybeDecrementPending() {
DVLOG(1) << "WebTransportThrottleContext::MaybeDecrementPending() this="
<< this << " pending_handshakes_= " << pending_handshakes_;
const auto now = base::TimeTicks::Now();
while (!pending_queue_.empty() && pending_queue_.top() <= now) {
pending_queue_.pop();
--pending_handshakes_;
}
throttle_context_->OnPendingQueueReady();
ProcessPendingQueue();
}
void WebTransportThrottleContext::PenaltyManager::ProcessPendingQueue() {
if (pending_queue_.empty()) {
return;
}
StartPendingQueueTimer(pending_queue_.top() - base::TimeTicks::Now());
}
void WebTransportThrottleContext::PenaltyManager::StopPendingQueueTimer() {
if (pending_queue_timer_.IsRunning()) {
pending_queue_timer_.Stop();
}
}
void WebTransportThrottleContext::PenaltyManager::StartPendingQueueTimer(
base::TimeDelta after) {
DVLOG(1) << "WebTransportThrottleContext::StartPendingQueueTimer() this="
<< this << " after=" << after
<< " pending_handshakes_= " << pending_handshakes_;
// This use of base::Unretained is safe because this timer is owned by this
// object and will be stopped on destruction.
pending_queue_timer_.Start(
FROM_HERE, after,
base::BindOnce(&PenaltyManager::MaybeDecrementPending,
base::Unretained(this)));
}
WebTransportThrottleContext::Tracker::Tracker(
base::WeakPtr<WebTransportThrottleContext> throttle_context)
: throttle_context_(throttle_context) {
DVLOG(1) << "WebTransportThrottleContext::Tracker()" << " this=" << this
<< " pending_handshakes_= "
<< throttle_context_->penalty_mgr_.PendingHandshakes();
DCHECK(throttle_context_);
DCHECK_LT(throttle_context_->penalty_mgr_.PendingHandshakes(),
kMaxPendingSessions);
throttle_context_->penalty_mgr_.AddPendingHandshakes();
}
WebTransportThrottleContext::Tracker::~Tracker() {
if (throttle_context_) {
throttle_context_->MaybeQueueHandshakeFailurePenalty();
}
}
void WebTransportThrottleContext::Tracker::OnHandshakeEstablished() {
DVLOG(1) << "WebTransportThrottleContext::Tracker::OnHandshakeEstablished()"
<< " this=" << this;
if (!throttle_context_)
return;
DVLOG(1) << " pending_handshakes_= "
<< throttle_context_->penalty_mgr_.PendingHandshakes();
DCHECK_GT(throttle_context_->penalty_mgr_.PendingHandshakes(), 0);
throttle_context_->penalty_mgr_.QueuePending(base::Milliseconds(10));
throttle_context_ = nullptr;
}
void WebTransportThrottleContext::Tracker::OnHandshakeFailed() {
DVLOG(1) << "WebTransportThrottleContext::Tracker::OnHandshakeFailed()"
<< " this=" << this;
if (!throttle_context_)
return;
DVLOG(1) << " pending_handshakes_= "
<< throttle_context_->penalty_mgr_.PendingHandshakes();
throttle_context_->MaybeQueueHandshakeFailurePenalty();
throttle_context_ = nullptr;
}
WebTransportThrottleContext::WebTransportThrottleContext()
: should_queue_handshake_failure_penalty_(
ShouldQueueHandshakeFailurePenalty()) {}
WebTransportThrottleContext::~WebTransportThrottleContext() = default;
WebTransportThrottleContext::ThrottleResult
WebTransportThrottleContext::PerformThrottle(
ThrottleDoneCallback on_throttle_done) {
DVLOG(1) << "WebTransportThrottleContext::PerformThrottle() this=" << this
<< " pending_handshakes_=" << penalty_mgr_.PendingHandshakes();
if (!penalty_mgr_.PendingQueueTimerIsRunning()) {
// If the timer was not running there may be some pending connections that
// were not cleaned up yet. May cause other handshakes to be started as a
// side-effect, but since they are unrelated this is harmless.
penalty_mgr_.MaybeDecrementPending();
}
if (penalty_mgr_.PendingHandshakes() +
static_cast<int>(throttled_connections_.size()) >=
kMaxPendingSessions) {
return ThrottleResult::kTooManyPendingSessions;
}
throttled_connections_.push(std::move(on_throttle_done));
if (!throttled_connections_timer_.IsRunning()) {
queue_head_time_ = base::TimeTicks::Now();
ScheduleThrottledConnection();
}
if (!penalty_mgr_.PendingQueueTimerIsRunning() &&
!throttled_connections_.empty()) {
penalty_mgr_.ProcessPendingQueue();
}
return ThrottleResult::kOk;
}
void WebTransportThrottleContext::MaybeQueueHandshakeFailurePenalty() {
if (should_queue_handshake_failure_penalty_) {
penalty_mgr_.QueuePending(base::Minutes(5));
return;
}
CHECK_GE(penalty_mgr_.PendingHandshakes(), 0);
penalty_mgr_.RemovePendingHandshakes();
}
base::WeakPtr<WebTransportThrottleContext>
WebTransportThrottleContext::GetWeakPtr() {
return weak_factory_.GetWeakPtr();
}
void WebTransportThrottleContext::OnPendingQueueReady() {
if (!throttled_connections_.empty()) {
ScheduleThrottledConnection();
}
}
void WebTransportThrottleContext::ScheduleThrottledConnection() {
DVLOG(1) << "WebTransportThrottleContext::ScheduleThrottledConnection() this="
<< this
<< " pending_handshakes_= " << penalty_mgr_.PendingHandshakes();
DCHECK(!throttled_connections_.empty());
if (penalty_mgr_.PendingHandshakes() == 0) {
DoOnThrottleDone();
return;
}
DCHECK_GT(penalty_mgr_.PendingHandshakes(), 0);
// Don't do the calculation for large values of `pending_handshakes_` to avoid
// integer overflow. If `pending_handshakes_` is 14, the result of the
// calculation is 81920, so it will always get truncated to 60000.
const int milliseconds_delay =
penalty_mgr_.PendingHandshakes() > 13
? 60000
: std::min(10 * (1 << (penalty_mgr_.PendingHandshakes() - 1)), 60000);
// We multiply the timeout by a random factor so that when a server falls over
// and the client code starts to accidentally DoS it, all the clients don't
// arrive at the same time when it recovers.
const double random_multiplier = base::RandDouble() + 0.5;
const base::TimeDelta delay =
base::Milliseconds(milliseconds_delay * random_multiplier);
DCHECK_GT(delay, base::Seconds(0));
const base::TimeTicks when = queue_head_time_ + delay;
const base::TimeDelta relative_delay = when - base::TimeTicks::Now();
if (relative_delay <= base::Seconds(0)) {
DVLOG(1) << "relative_delay=" << relative_delay << " so firing immediately";
DoOnThrottleDone();
return;
}
DVLOG(1) << "Starting throttled_connections_timer_ with delay="
<< relative_delay;
// It is safe to use base::Unretained here because the timer is owned by this
// object and will be stopped if this object is destroyed.
throttled_connections_timer_.Start(
FROM_HERE, relative_delay,
base::BindOnce(&WebTransportThrottleContext::StartOneConnection,
base::Unretained(this)));
}
void WebTransportThrottleContext::DoOnThrottleDone() {
DVLOG(1) << "WebTransportThrottleContext::DoOnThrottleDone() this=" << this
<< " pending_handshakes_= " << penalty_mgr_.PendingHandshakes()
<< " throttled_connections_.size()="
<< throttled_connections_.size();
DCHECK(!throttled_connections_.empty());
auto on_throttle_done = std::move(throttled_connections_.front());
throttled_connections_.pop();
queue_head_time_ = base::TimeTicks::Now();
if (throttled_connections_.empty()) {
penalty_mgr_.StopPendingQueueTimer();
}
auto tracker = std::make_unique<Tracker>(GetWeakPtr());
std::move(on_throttle_done).Run(std::move(tracker));
}
void WebTransportThrottleContext::StartOneConnection() {
DVLOG(1) << "WebTransportThrottleContext::StartOneConnection() this=" << this
<< " pending_handshakes_= " << penalty_mgr_.PendingHandshakes();
if (throttled_connections_.empty())
return;
DoOnThrottleDone();
if (!throttled_connections_.empty()) {
ScheduleThrottledConnection();
}
}
} // namespace content