i2pd/libi2pd/TunnelEndpoint.h

/*
* Copyright (c) 2013-2021, 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 TUNNEL_ENDPOINT_H__
#define TUNNEL_ENDPOINT_H__

#include <inttypes.h>
#include <vector>
#include <string>
#include <unordered_map>
#include "I2NPProtocol.h"
#include "TunnelBase.h"

namespace i2p {
    namespace tunnel {
        class TunnelEndpoint {
            struct TunnelMessageBlockEx : public TunnelMessageBlock {
                uint64_t receiveTime; // milliseconds since epoch
                uint8_t nextFragmentNum;
            };

            struct Fragment {
                Fragment(bool last, uint64_t t, size_t size) : isLastFragment(last), receiveTime(t), data(size) {};
                bool isLastFragment;
                uint64_t receiveTime; // milliseconds since epoch
                std::vector<uint8_t> data;
            };

        public:

            TunnelEndpoint(bool isInbound) : m_IsInbound(isInbound), m_NumReceivedBytes(0), m_CurrentMsgID(0) {};

            ~TunnelEndpoint();

            size_t GetNumReceivedBytes() const { return m_NumReceivedBytes; };

            void Cleanup();

            void HandleDecryptedTunnelDataMsg(std::shared_ptr<I2NPMessage> msg);

        private:

            void
            HandleFollowOnFragment(uint32_t msgID, bool isLastFragment, uint8_t fragmentNum, const uint8_t *fragment,
                                   size_t size);

            bool ConcatFollowOnFragment(TunnelMessageBlockEx &msg, const uint8_t *fragment,
                                        size_t size) const; // true if success
            void HandleCurrenMessageFollowOnFragment(const uint8_t *fragment, size_t size, bool isLastFragment);

            void HandleNextMessage(const TunnelMessageBlock &msg);

            void
            AddOutOfSequenceFragment(uint32_t msgID, uint8_t fragmentNum, bool isLastFragment, const uint8_t *fragment,
                                     size_t size);

            bool ConcatNextOutOfSequenceFragment(uint32_t msgID, TunnelMessageBlockEx &msg); // true if something added
            void HandleOutOfSequenceFragments(uint32_t msgID, TunnelMessageBlockEx &msg);

            void AddIncompleteCurrentMessage();

        private:

            std::unordered_map<uint32_t, TunnelMessageBlockEx> m_IncompleteMessages;
            std::unordered_map<uint64_t, std::unique_ptr<Fragment> > m_OutOfSequenceFragments; // ((msgID << 8) + fragment#)->fragment
            bool m_IsInbound;
            size_t m_NumReceivedBytes;
            TunnelMessageBlockEx m_CurrentMessage;
            uint32_t m_CurrentMsgID;
        };
    }
}

#endif