i2pd/libi2pd_client/I2PService.h

/*
* Copyright (c) 2013-2020, The PurpleI2P Project
*
* This file is part of Purple i2pd project and licensed under BSD3
*
* See full license text in LICENSE file at top of project tree
*/

#ifndef I2PSERVICE_H__
#define I2PSERVICE_H__

#include <atomic>
#include <mutex>
#include <unordered_set>
#include <memory>
#include <boost/asio.hpp>
#include "Destination.h"
#include "Identity.h"
#include "AddressBook.h"

namespace i2p {
    namespace client {
        class I2PServiceHandler;

        class I2PService : public std::enable_shared_from_this<I2PService> {
        public:

            typedef std::function<void(const boost::system::error_code &)> ReadyCallback;

        public:

            I2PService(std::shared_ptr <ClientDestination> localDestination = nullptr);

            I2PService(i2p::data::SigningKeyType kt);

            virtual ~I2PService();

            inline void AddHandler(std::shared_ptr <I2PServiceHandler> conn) {
                std::unique_lock <std::mutex> l(m_HandlersMutex);
                m_Handlers.insert(conn);
            }

            inline void RemoveHandler(std::shared_ptr <I2PServiceHandler> conn) {
                std::unique_lock <std::mutex> l(m_HandlersMutex);
                m_Handlers.erase(conn);
            }

            void ClearHandlers();

            void SetConnectTimeout(uint32_t timeout);

            void AddReadyCallback(ReadyCallback cb);

            inline std::shared_ptr <ClientDestination> GetLocalDestination() { return m_LocalDestination; }

            inline std::shared_ptr<const ClientDestination> GetLocalDestination() const { return m_LocalDestination; }

            inline void SetLocalDestination(std::shared_ptr <ClientDestination> dest) {
                if (m_LocalDestination) m_LocalDestination->Release();
                if (dest) dest->Acquire();
                m_LocalDestination = dest;
            }

            void CreateStream(StreamRequestComplete streamRequestComplete, const std::string &dest, int port = 0);

            void CreateStream(StreamRequestComplete complete, std::shared_ptr<const Address> address, int port);

            inline boost::asio::io_service &GetService() { return m_LocalDestination->GetService(); }

            virtual void Start() = 0;

            virtual void Stop() = 0;

            virtual const char *GetName() { return "Generic I2P Service"; }

        private:

            void TriggerReadyCheckTimer();

            void HandleReadyCheckTimer(const boost::system::error_code &ec);

        private:

            std::shared_ptr <ClientDestination> m_LocalDestination;
            std::unordered_set <std::shared_ptr<I2PServiceHandler>> m_Handlers;
            std::mutex m_HandlersMutex;
            std::vector <std::pair<ReadyCallback, uint32_t>> m_ReadyCallbacks;
            boost::asio::deadline_timer m_ReadyTimer;
            bool m_ReadyTimerTriggered;
            uint32_t m_ConnectTimeout;

            const size_t NEVER_TIMES_OUT = 0;

        public:

            bool isUpdated; // transient, used during reload only
        };

        /*Simple interface for I2PHandlers, allows detection of finalization amongst other things */
        class I2PServiceHandler {
        public:

            I2PServiceHandler(I2PService *parent) : m_Service(parent), m_Dead(false) {}

            virtual ~I2PServiceHandler() {}

            //If you override this make sure you call it from the children
            virtual void Handle() {}; //Start handling the socket

            void Terminate() { Kill(); };

        protected:

            // Call when terminating or handing over to avoid race conditions
            inline bool Kill() { return m_Dead.exchange(true); }

            // Call to know if the handler is dead
            inline bool Dead() { return m_Dead; }

            // Call when done to clean up (make sure Kill is called first)
            inline void Done(std::shared_ptr <I2PServiceHandler> me) { if (m_Service) m_Service->RemoveHandler(me); }

            // Call to talk with the owner
            inline I2PService *GetOwner() { return m_Service; }

        private:

            I2PService *m_Service;
            std::atomic<bool> m_Dead; //To avoid cleaning up multiple times
        };

        const size_t TCP_IP_PIPE_BUFFER_SIZE = 8192 * 8;

        // bidirectional pipe for 2 tcp/ip sockets
        class TCPIPPipe : public I2PServiceHandler, public std::enable_shared_from_this<TCPIPPipe> {
        public:

            TCPIPPipe(I2PService *owner, std::shared_ptr <boost::asio::ip::tcp::socket> upstream,
                      std::shared_ptr <boost::asio::ip::tcp::socket> downstream);

            ~TCPIPPipe();

            void Start();

        protected:

            void Terminate();

            void AsyncReceiveUpstream();

            void AsyncReceiveDownstream();

            void HandleUpstreamReceived(const boost::system::error_code &ecode, std::size_t bytes_transferred);

            void HandleDownstreamReceived(const boost::system::error_code &ecode, std::size_t bytes_transferred);

            void HandleUpstreamWrite(const boost::system::error_code &ecode);

            void HandleDownstreamWrite(const boost::system::error_code &ecode);

            void UpstreamWrite(size_t len);

            void DownstreamWrite(size_t len);

        private:

            uint8_t m_upstream_to_down_buf[TCP_IP_PIPE_BUFFER_SIZE], m_downstream_to_up_buf[TCP_IP_PIPE_BUFFER_SIZE];
            uint8_t m_upstream_buf[TCP_IP_PIPE_BUFFER_SIZE], m_downstream_buf[TCP_IP_PIPE_BUFFER_SIZE];
            std::shared_ptr <boost::asio::ip::tcp::socket> m_up, m_down;
        };

        /* TODO: support IPv6 too */
        //This is a service that listens for connections on the IP network and interacts with I2P
        class TCPIPAcceptor : public I2PService {
        public:

            TCPIPAcceptor(const std::string &address, int port,
                          std::shared_ptr <ClientDestination> localDestination = nullptr) :
                    I2PService(localDestination),
                    m_LocalEndpoint(boost::asio::ip::address::from_string(address), port),
                    m_Timer(GetService()) {}

            TCPIPAcceptor(const std::string &address, int port, i2p::data::SigningKeyType kt) :
                    I2PService(kt),
                    m_LocalEndpoint(boost::asio::ip::address::from_string(address), port),
                    m_Timer(GetService()) {}

            virtual ~TCPIPAcceptor() { TCPIPAcceptor::Stop(); }

            //If you override this make sure you call it from the children
            void Start();

            //If you override this make sure you call it from the children
            void Stop();

            const boost::asio::ip::tcp::endpoint &GetLocalEndpoint() const { return m_LocalEndpoint; };

            virtual const char *GetName() { return "Generic TCP/IP accepting daemon"; }

        protected:

            virtual std::shared_ptr <I2PServiceHandler>
            CreateHandler(std::shared_ptr <boost::asio::ip::tcp::socket> socket) = 0;

        private:

            void Accept();

            void
            HandleAccept(const boost::system::error_code &ecode, std::shared_ptr <boost::asio::ip::tcp::socket> socket);

            boost::asio::ip::tcp::endpoint m_LocalEndpoint;
            std::unique_ptr <boost::asio::ip::tcp::acceptor> m_Acceptor;
            boost::asio::deadline_timer m_Timer;
        };
    }
}

#endif