i2pd/Streaming.h

#ifndef STREAMING_H__
#define STREAMING_H__

#include <inttypes.h>
#include <string>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <functional>
#include <memory>
#include <mutex>
#include <boost/asio.hpp>
#include "util/I2PEndian.h"
#include "Identity.h"
#include "LeaseSet.h"
#include "I2NPProtocol.h"
#include "Garlic.h"
#include "Tunnel.h"

namespace i2p
{
namespace client
{
    class ClientDestination;
}
namespace stream
{
    const uint16_t PACKET_FLAG_SYNCHRONIZE = 0x0001;
    const uint16_t PACKET_FLAG_CLOSE = 0x0002;
    const uint16_t PACKET_FLAG_RESET = 0x0004;
    const uint16_t PACKET_FLAG_SIGNATURE_INCLUDED = 0x0008;
    const uint16_t PACKET_FLAG_SIGNATURE_REQUESTED = 0x0010;
    const uint16_t PACKET_FLAG_FROM_INCLUDED = 0x0020;
    const uint16_t PACKET_FLAG_DELAY_REQUESTED = 0x0040;
    const uint16_t PACKET_FLAG_MAX_PACKET_SIZE_INCLUDED = 0x0080;
    const uint16_t PACKET_FLAG_PROFILE_INTERACTIVE = 0x0100;
    const uint16_t PACKET_FLAG_ECHO = 0x0200;
    const uint16_t PACKET_FLAG_NO_ACK = 0x0400;

    const size_t STREAMING_MTU = 1730;
    const size_t MAX_PACKET_SIZE = 4096;
    const size_t COMPRESSION_THRESHOLD_SIZE = 66;   
    const int ACK_SEND_TIMEOUT = 200; // in milliseconds
    const int MAX_NUM_RESEND_ATTEMPTS = 6;  
    const int WINDOW_SIZE = 6; // in messages
    const int MIN_WINDOW_SIZE = 1;
    const int MAX_WINDOW_SIZE = 128;        
    const int INITIAL_RTT = 8000; // in milliseconds
    const int INITIAL_RTO = 9000; // in milliseconds
    
    struct Packet
    {
        size_t len, offset;
        uint8_t buf[MAX_PACKET_SIZE];   
        uint64_t sendTime;
        
        Packet (): len (0), offset (0), sendTime (0) {};
        uint8_t * GetBuffer () { return buf + offset; };
        size_t GetLength () const { return len - offset; };

        uint32_t GetSendStreamID () const { return bufbe32toh (buf); };
        uint32_t GetReceiveStreamID () const { return bufbe32toh (buf + 4); };
        uint32_t GetSeqn () const { return bufbe32toh (buf + 8); };
        uint32_t GetAckThrough () const { return bufbe32toh (buf + 12); };
        uint8_t GetNACKCount () const { return buf[16]; };
        uint32_t GetNACK (int i) const { return bufbe32toh (buf + 17 + 4 * i); };
        const uint8_t * GetOption () const { return buf + 17 + GetNACKCount ()*4 + 3; }; // 3 = resendDelay + flags
        uint16_t GetFlags () const { return bufbe16toh (GetOption () - 2); };
        uint16_t GetOptionSize () const { return bufbe16toh (GetOption ()); };
        const uint8_t * GetOptionData () const { return GetOption () + 2; };
        const uint8_t * GetPayload () const { return GetOptionData () + GetOptionSize (); };

        bool IsSYN () const { return GetFlags () & PACKET_FLAG_SYNCHRONIZE; };
        bool IsNoAck () const { return GetFlags () & PACKET_FLAG_NO_ACK; };
    };  

    struct PacketCmp
    {
        bool operator() (const Packet * p1, const Packet * p2) const
        {   
            return p1->GetSeqn () < p2->GetSeqn (); 
        };
    };  

    enum StreamStatus
    {
        eStreamStatusNew = 0,
        eStreamStatusOpen,
        eStreamStatusReset,
        eStreamStatusClosing,
        eStreamStatusClosed
    };  
    
    class StreamingDestination;
    class Stream: public std::enable_shared_from_this<Stream>
    {   
        public:

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

            Stream (boost::asio::io_service& service, StreamingDestination& local, 
                std::shared_ptr<const i2p::data::LeaseSet> remote, int port = 0); // outgoing
            Stream (boost::asio::io_service& service, StreamingDestination& local); // incoming         

            ~Stream ();
            uint32_t GetSendStreamID () const { return m_SendStreamID; };
            uint32_t GetRecvStreamID () const { return m_RecvStreamID; };
            std::shared_ptr<const i2p::data::LeaseSet> GetRemoteLeaseSet () const { return m_RemoteLeaseSet; };
            const i2p::data::IdentityEx& GetRemoteIdentity () const { return m_RemoteIdentity; };
            bool IsOpen () const { return m_Status == eStreamStatusOpen; };
            bool IsEstablished () const { return m_SendStreamID; };
            StreamStatus GetStatus () const { return m_Status; };
            StreamingDestination& GetLocalDestination () { return m_LocalDestination; };
            
            void HandleNextPacket (Packet * packet);
            size_t Send (const uint8_t * buf, size_t len);
            void AsyncSend (const uint8_t * buf, size_t len, SendHandler handler);
            
            template<typename Buffer, typename ReceiveHandler>
            void AsyncReceive (const Buffer& buffer, ReceiveHandler handler, int timeout = 0);
            size_t ReadSome (uint8_t * buf, size_t len) { return ConcatenatePackets (buf, len); };
            
            void Close ();
            void Cancel () { m_ReceiveTimer.cancel (); };

            size_t GetNumSentBytes () const { return m_NumSentBytes; };
            size_t GetNumReceivedBytes () const { return m_NumReceivedBytes; };
            size_t GetSendQueueSize () const { return m_SentPackets.size (); };
            size_t GetReceiveQueueSize () const { return m_ReceiveQueue.size (); };
            size_t GetSendBufferSize () const { return m_SendBuffer.rdbuf ()->in_avail (); };
            int GetWindowSize () const { return m_WindowSize; };
            int GetRTT () const { return m_RTT; };
            
        private:

            void Terminate ();

            void SendBuffer ();
            void SendQuickAck ();
            void SendClose ();
            bool SendPacket (Packet * packet);
            void SendPackets (const std::vector<Packet *>& packets);

            void SavePacket (Packet * packet);
            void ProcessPacket (Packet * packet);
            void ProcessAck (Packet * packet);
            size_t ConcatenatePackets (uint8_t * buf, size_t len);

            void UpdateCurrentRemoteLease (bool expired = false);
            
            template<typename Buffer, typename ReceiveHandler>
            void HandleReceiveTimer (const boost::system::error_code& ecode, const Buffer& buffer, ReceiveHandler handler);
            
            void ScheduleResend ();
            void HandleResendTimer (const boost::system::error_code& ecode);
            void HandleAckSendTimer (const boost::system::error_code& ecode);

            std::shared_ptr<I2NPMessage> CreateDataMessage (const uint8_t * payload, size_t len);
            
        private:

            boost::asio::io_service& m_Service;
            uint32_t m_SendStreamID, m_RecvStreamID, m_SequenceNumber;
            int32_t m_LastReceivedSequenceNumber;
            StreamStatus m_Status;
            bool m_IsAckSendScheduled;
            StreamingDestination& m_LocalDestination;
            i2p::data::IdentityEx m_RemoteIdentity;
            std::shared_ptr<const i2p::data::LeaseSet> m_RemoteLeaseSet;
            std::shared_ptr<i2p::garlic::GarlicRoutingSession> m_RoutingSession;
            i2p::data::Lease m_CurrentRemoteLease;
            std::shared_ptr<i2p::tunnel::OutboundTunnel> m_CurrentOutboundTunnel;
            std::queue<Packet *> m_ReceiveQueue;
            std::set<Packet *, PacketCmp> m_SavedPackets;
            std::set<Packet *, PacketCmp> m_SentPackets;
            boost::asio::deadline_timer m_ReceiveTimer, m_ResendTimer, m_AckSendTimer;
            size_t m_NumSentBytes, m_NumReceivedBytes;
            uint16_t m_Port;

            std::mutex m_SendBufferMutex;
            std::stringstream m_SendBuffer;
            int m_WindowSize, m_RTT, m_RTO;
            uint64_t m_LastWindowSizeIncreaseTime;
            int m_NumResendAttempts;
            SendHandler m_SendHandler;
    };

    class StreamingDestination
    {
        public:

            typedef std::function<void (std::shared_ptr<Stream>)> Acceptor;

            StreamingDestination (i2p::client::ClientDestination& owner, uint16_t localPort = 0): 
                m_Owner (owner), m_LocalPort (localPort) {};
            ~StreamingDestination () {};    

            void Start ();
            void Stop ();

            std::shared_ptr<Stream> CreateNewOutgoingStream (std::shared_ptr<const i2p::data::LeaseSet> remote, int port = 0);
            void DeleteStream (std::shared_ptr<Stream> stream);         
            void SetAcceptor (const Acceptor& acceptor) { m_Acceptor = acceptor; };
            void ResetAcceptor () { if (m_Acceptor) m_Acceptor (nullptr); m_Acceptor = nullptr; };
            bool IsAcceptorSet () const { return m_Acceptor != nullptr; };  
            i2p::client::ClientDestination& GetOwner () { return m_Owner; };
            uint16_t GetLocalPort () const { return m_LocalPort; };

            void HandleDataMessagePayload (const uint8_t * buf, size_t len);

        private:        
    
            void HandleNextPacket (Packet * packet);
            std::shared_ptr<Stream> CreateNewIncomingStream ();

        private:

            i2p::client::ClientDestination& m_Owner;
            uint16_t m_LocalPort;
            std::mutex m_StreamsMutex;
            std::map<uint32_t, std::shared_ptr<Stream> > m_Streams;
            Acceptor m_Acceptor;
            
        public:

            // for HTTP only
            const decltype(m_Streams)& GetStreams () const { return m_Streams; };
    };      

//-------------------------------------------------

    template<typename Buffer, typename ReceiveHandler>
    void Stream::AsyncReceive (const Buffer& buffer, ReceiveHandler handler, int timeout)
    {
        auto s = shared_from_this();
        m_Service.post ([=](void)
        {
            if (!m_ReceiveQueue.empty () || m_Status == eStreamStatusReset)
                s->HandleReceiveTimer (boost::asio::error::make_error_code (boost::asio::error::operation_aborted), buffer, handler);
            else
            {
                s->m_ReceiveTimer.expires_from_now (boost::posix_time::seconds(timeout));
                s->m_ReceiveTimer.async_wait ([=](const boost::system::error_code& ecode)
                    { s->HandleReceiveTimer (ecode, buffer, handler); });
            }
        }); 
    }

    template<typename Buffer, typename ReceiveHandler>
    void Stream::HandleReceiveTimer (const boost::system::error_code& ecode, const Buffer& buffer, ReceiveHandler handler)
    {
        size_t received = ConcatenatePackets (boost::asio::buffer_cast<uint8_t *>(buffer), boost::asio::buffer_size(buffer));
        if (received > 0)
            handler (boost::system::error_code (), received);
        else if (ecode == boost::asio::error::operation_aborted)
        {   
            // timeout not expired  
            if (m_Status == eStreamStatusReset)
                handler (boost::asio::error::make_error_code (boost::asio::error::connection_reset), 0);
            else
                handler (boost::asio::error::make_error_code (boost::asio::error::operation_aborted), 0); 
        }   
        else
            // timeout expired
            handler (boost::asio::error::make_error_code (boost::asio::error::timed_out), received);
    }
}       
}   

#endif