communication_layer.h

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// MIT License
//
// Copyright (c) 2020 Lennart Braun
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
 
#pragma once
 
#include <atomic>
#include <cstddef>
#include <functional>
#include <memory>
#include <vector>
 
// Undefine Windows macros that collide with function names in MOTION.
#ifdef SendMessage
#undef SendMessage
#endif
 
#ifdef GetMessage
#undef GetMessage
#endif
 
#include "fbs_headers/message_generated.h"
#include "transport.h"
 
namespace encrypto::motion {
 
class Logger;
 
}  // namespace encrypto::motion
 
namespace encrypto::motion::communication {
 
class MessageHandler;
struct TransportStatistics;
 
// Central interface for all communication related functionality
//
// Allows to send messages to other parties and to register handlers for
// specific message types.
class CommunicationLayer {
 public:
  CommunicationLayer(std::size_t my_id, std::vector<std::unique_ptr<Transport>>&& transports);
  CommunicationLayer(std::size_t my_id, std::vector<std::unique_ptr<Transport>>&& transports,
                     std::shared_ptr<Logger> logger);
  ~CommunicationLayer();
 
  std::size_t GetNumberOfParties() const { return number_of_parties_; }
  std::size_t GetMyId() const { return my_id_; }
 
  // Start communication
  void Start();
  void Synchronize();
 
  // Send a message to a specified party
  void SendMessage(std::size_t party_id, std::vector<std::uint8_t>&& message);
  void SendMessage(std::size_t party_id, const std::vector<std::uint8_t>& message);
  void SendMessage(std::size_t party_id, std::shared_ptr<const std::vector<std::uint8_t>> message);
  void SendMessage(std::size_t party_id, flatbuffers::FlatBufferBuilder&& message_builder);
 
  // Send a message to all other parties
  void BroadcastMessage(std::vector<std::uint8_t>&& message);
  void BroadcastMessage(const std::vector<std::uint8_t>& message);
  void BroadcastMessage(std::shared_ptr<const std::vector<std::uint8_t>> message);
  void BroadcastMessage(flatbuffers::FlatBufferBuilder&& message_builder);
 
  // Factory function for creating message handlers
  using MessageHandlerFunction =
      std::function<std::shared_ptr<MessageHandler>(std::size_t party_id)>;
  // Register message handlers for given types
  void RegisterMessageHandler(MessageHandlerFunction,
                              const std::vector<MessageType>& message_types);
  // Deregister any message handler registered for the given types
  void DeregisterMessageHandler(const std::vector<MessageType>& message_types);
  // Return the message handler registered for the given type.
  // Throws if no handler was registered for this type.
  MessageHandler& GetMessageHandler(std::size_t party_id, MessageType type);
 
  // Register handler to be called if no matchin handler is installed.
  void RegisterFallbackMessageHandler(MessageHandlerFunction);
  MessageHandler& GetFallbackMessageHandler(std::size_t party_id);
 
  // shutdown the communication layer
  void Shutdown();
 
  std::vector<TransportStatistics> GetTransportStatistics() const noexcept;
 
  void SetLogger(std::shared_ptr<Logger> logger);
 
 private:
  struct CommunicationLayerImplementation;
 
  std::size_t my_id_;
  std::size_t number_of_parties_;
  std::unique_ptr<CommunicationLayerImplementation> implementation_;
  bool is_started_;
  bool is_shutdown_;
  std::shared_ptr<Logger> logger_;
};
 
// Create a set of communication layers connected by dummy transports
std::vector<std::unique_ptr<CommunicationLayer>> MakeDummyCommunicationLayers(
    std::size_t number_of_parties);
 
// Create a set of communication layers connected by local TCP connections
std::vector<std::unique_ptr<CommunicationLayer>> MakeLocalTcpCommunicationLayers(
    std::size_t number_of_parties, bool ipv6 = true);
 
}  // namespace encrypto::motion::communication