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// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef DISCOVERY_MDNS_MDNS_RANDOM_H_
#define DISCOVERY_MDNS_MDNS_RANDOM_H_
#include <random>
#include "platform/api/time.h"
namespace openscreen {
namespace discovery {
class MdnsRandom {
public:
// RFC 6762 Section 5.2
// https://tools.ietf.org/html/rfc6762#section-5.2
Clock::duration GetInitialQueryDelay() {
return std::chrono::milliseconds{initial_query_delay_(random_engine_)};
}
double GetRecordTtlVariation() {
return record_ttl_variation_(random_engine_);
}
// RFC 6762 Section 6
// https://tools.ietf.org/html/rfc6762#section-6
Clock::duration GetSharedRecordResponseDelay() {
return std::chrono::milliseconds{
shared_record_response_delay_(random_engine_)};
}
Clock::duration GetTruncatedQueryResponseDelay() {
return std::chrono::milliseconds{
truncated_query_response_delay_(random_engine_)};
}
Clock::duration GetInitialProbeDelay() {
return std::chrono::milliseconds{
probe_initialization_delay_(random_engine_)};
}
private:
static constexpr int64_t kMinimumInitialQueryDelayMs = 20;
static constexpr int64_t kMaximumInitialQueryDelayMs = 120;
static constexpr double kMinimumTtlVariation = 0.0;
static constexpr double kMaximumTtlVariation = 0.02;
static constexpr int64_t kMinimumSharedRecordResponseDelayMs = 20;
static constexpr int64_t kMaximumSharedRecordResponseDelayMs = 120;
static constexpr int64_t kMinimumTruncatedQueryResponseDelayMs = 400;
static constexpr int64_t kMaximumTruncatedQueryResponseDelayMs = 500;
static constexpr int64_t kMinimumProbeInitializationDelayMs = 0;
static constexpr int64_t kMaximumProbeInitializationDelayMs = 250;
std::default_random_engine random_engine_{std::random_device{}()};
std::uniform_int_distribution<int64_t> initial_query_delay_{
kMinimumInitialQueryDelayMs, kMaximumInitialQueryDelayMs};
std::uniform_real_distribution<double> record_ttl_variation_{
kMinimumTtlVariation, kMaximumTtlVariation};
std::uniform_int_distribution<int64_t> shared_record_response_delay_{
kMinimumSharedRecordResponseDelayMs, kMaximumSharedRecordResponseDelayMs};
std::uniform_int_distribution<int64_t> truncated_query_response_delay_{
kMinimumTruncatedQueryResponseDelayMs,
kMaximumTruncatedQueryResponseDelayMs};
std::uniform_int_distribution<int64_t> probe_initialization_delay_{
kMinimumProbeInitializationDelayMs, kMaximumProbeInitializationDelayMs};
};
} // namespace discovery
} // namespace openscreen
#endif // DISCOVERY_MDNS_MDNS_RANDOM_H_
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