extension_throttle_simulation_unittest.cc

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif

// The tests in this file attempt to verify the following through simulation:
// a) That a server experiencing overload will actually benefit from the
//    anti-DDoS throttling logic, i.e. that its traffic spike will subside
//    and be distributed over a longer period of time;
// b) That "well-behaved" clients of a server under DDoS attack actually
//    benefit from the anti-DDoS throttling logic; and
// c) That the approximate increase in "perceived downtime" introduced by
//    anti-DDoS throttling for various different actual downtimes is what
//    we expect it to be.

#include <stdarg.h>
#include <stddef.h>

#include <cmath>
#include <limits>
#include <memory>
#include <vector>

#include "base/environment.h"
#include "base/memory/ptr_util.h"
#include "base/memory/raw_ptr.h"
#include "base/rand_util.h"
#include "base/test/task_environment.h"
#include "base/time/time.h"
#include "extensions/renderer/extension_throttle_entry.h"
#include "extensions/renderer/extension_throttle_test_support.h"
#include "testing/gtest/include/gtest/gtest.h"

TimeTicks;
BackoffEntry;

namespace extensions {
namespace {

// Set this variable in your environment if you want to see verbose results
// of the simulation tests.
const char kShowSimulationVariableName[] = …;

// Prints output only if a given environment variable is set. We use this
// to not print any output for human evaluation when the test is run without
// supervision.
void VerboseOut(const char* format, ...) { … }

// A simple two-phase discrete time simulation. Actors are added in the order
// they should take action at every tick of the clock. Ticks of the clock
// are two-phase:
// - Phase 1 advances every actor's time to a new absolute time.
// - Phase 2 asks each actor to perform their action.
class DiscreteTimeSimulation { … };

// Represents a web server in a simulation of a server under attack by
// a lot of clients. Must be added to the simulation's list of actors
// after all |Requester| objects.
class Server : public DiscreteTimeSimulation::Actor { … };

// Mock throttler entry used by Requester class.
class MockExtensionThrottleEntry : public ExtensionThrottleEntry { … };

// Registry of results for a class of |Requester| objects (e.g. attackers vs.
// regular clients).
class RequesterResults { … };

// Represents an Requester in a simulated DDoS situation, that periodically
// requests a specific resource.
class Requester : public DiscreteTimeSimulation::Actor { … };

void SimulateAttack(Server* server,
                    RequesterResults* attacker_results,
                    RequesterResults* client_results,
                    bool enable_throttling) { … }

TEST(URLRequestThrottlerSimulation, HelpsInAttack) { … }

// Returns the downtime perceived by the client, as a ratio of the
// actual downtime.
double SimulateDowntime(const base::TimeDelta& duration,
                        const base::TimeDelta& average_client_interval,
                        bool enable_throttling) { … }

TEST(URLRequestThrottlerSimulation, PerceivedDowntimeRatio) { … }

}  // namespace
}  // namespace extensions
chromium/extensions/renderer/extension_throttle_simulation_unittest.cc
