| // 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_ |