text: /*
  * 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 I2PTUNNEL_H__
  #define I2PTUNNEL_H__
  
  #include <inttypes.h>
  #include <string>
  #include <set>
  #include <tuple>
  #include <memory>
  #include <sstream>
  #include <boost/asio.hpp>
  #include "Identity.h"
  #include "Destination.h"
  #include "Datagram.h"
  #include "Streaming.h"
  #include "I2PService.h"
  #include "AddressBook.h"
  
  namespace i2p
  {
  namespace client
  {
  	const size_t I2P_TUNNEL_CONNECTION_BUFFER_SIZE = 65536;
  	const int I2P_TUNNEL_CONNECTION_MAX_IDLE = 3600; // in seconds
  	const int I2P_TUNNEL_DESTINATION_REQUEST_TIMEOUT = 10; // in seconds
  	// for HTTP tunnels
  	const char X_I2P_DEST_HASH[] = "X-I2P-DestHash"; // hash  in base64
  	const char X_I2P_DEST_B64[] = "X-I2P-DestB64"; // full address in base64
  	const char X_I2P_DEST_B32[] = "X-I2P-DestB32"; // .b32.i2p address
  
  	class I2PTunnelConnection: public I2PServiceHandler, public std::enable_shared_from_this<I2PTunnelConnection>
  	{
  		public:
  
  			I2PTunnelConnection (I2PService * owner, std::shared_ptr<boost::asio::ip::tcp::socket> socket,
  				std::shared_ptr<const i2p::data::LeaseSet> leaseSet, int port = 0); // to I2P
  			I2PTunnelConnection (I2PService * owner, std::shared_ptr<boost::asio::ip::tcp::socket> socket,
  				std::shared_ptr<i2p::stream::Stream> stream); // to I2P using simplified API
  			I2PTunnelConnection (I2PService * owner, std::shared_ptr<i2p::stream::Stream> stream,  std::shared_ptr<boost::asio::ip::tcp::socket> socket,
  				const boost::asio::ip::tcp::endpoint& target, bool quiet = true); // from I2P
  			~I2PTunnelConnection ();
  			void I2PConnect (const uint8_t * msg = nullptr, size_t len = 0);
  			void Connect (bool isUniqueLocal = true);
  
  		protected:
  
  			void Terminate ();
  
  			void Receive ();
  			void HandleReceived (const boost::system::error_code& ecode, std::size_t bytes_transferred);
  			virtual void Write (const uint8_t * buf, size_t len); // can be overloaded
  			void HandleWrite (const boost::system::error_code& ecode);
  
  			void StreamReceive ();
  			void HandleStreamReceive (const boost::system::error_code& ecode, std::size_t bytes_transferred);
  			void HandleConnect (const boost::system::error_code& ecode);
  
  			std::shared_ptr<const boost::asio::ip::tcp::socket> GetSocket () const { return m_Socket; };
  
  		private:
  
  			uint8_t m_Buffer[I2P_TUNNEL_CONNECTION_BUFFER_SIZE], m_StreamBuffer[I2P_TUNNEL_CONNECTION_BUFFER_SIZE];
  			std::shared_ptr<boost::asio::ip::tcp::socket> m_Socket;
  			std::shared_ptr<i2p::stream::Stream> m_Stream;
  			boost::asio::ip::tcp::endpoint m_RemoteEndpoint;
  			bool m_IsQuiet; // don't send destination
  	};
  
  	class I2PClientTunnelConnectionHTTP: public I2PTunnelConnection
  	{
  		public:
  
  			I2PClientTunnelConnectionHTTP (I2PService * owner, std::shared_ptr<boost::asio::ip::tcp::socket> socket,
  				std::shared_ptr<i2p::stream::Stream> stream):
  				I2PTunnelConnection (owner, socket, stream), m_HeaderSent (false),
  				m_ConnectionSent (false), m_ProxyConnectionSent (false) {};
  
  		protected:
  
  			void Write (const uint8_t * buf, size_t len);
  
  		private:
  
  			std::stringstream m_InHeader, m_OutHeader;
  			bool m_HeaderSent, m_ConnectionSent, m_ProxyConnectionSent;
  	};
  
  	class I2PServerTunnelConnectionHTTP: public I2PTunnelConnection
  	{
  		public:
  
  			I2PServerTunnelConnectionHTTP (I2PService * owner, std::shared_ptr<i2p::stream::Stream> stream,
  				std::shared_ptr<boost::asio::ip::tcp::socket> socket,
  				const boost::asio::ip::tcp::endpoint& target, const std::string& host);
  
  		protected:
  
  			void Write (const uint8_t * buf, size_t len);
  
  		private:
  
  			std::string m_Host;
  			std::stringstream m_InHeader, m_OutHeader;
  			bool m_HeaderSent;
  			std::shared_ptr<const i2p::data::IdentityEx> m_From;
  	};
  
  	class I2PTunnelConnectionIRC: public I2PTunnelConnection
  	{
  		public:
  
  			I2PTunnelConnectionIRC (I2PService * owner, std::shared_ptr<i2p::stream::Stream> stream,
  				std::shared_ptr<boost::asio::ip::tcp::socket> socket,
  				const boost::asio::ip::tcp::endpoint& target, const std::string& m_WebircPass);
  
  		protected:
  
  			void Write (const uint8_t * buf, size_t len);
  
  		private:
  
  			std::shared_ptr<const i2p::data::IdentityEx> m_From;
  			std::stringstream m_OutPacket, m_InPacket;
  			bool m_NeedsWebIrc;
  			std::string m_WebircPass;
  	};
  
  
  	class I2PClientTunnel: public TCPIPAcceptor
  	{
  		protected:
  
  			// Implements TCPIPAcceptor
  			std::shared_ptr<I2PServiceHandler> CreateHandler(std::shared_ptr<boost::asio::ip::tcp::socket> socket);
  
  		public:
  
  			I2PClientTunnel (const std::string& name, const std::string& destination,
  				const std::string& address, int port, std::shared_ptr<ClientDestination> localDestination, int destinationPort = 0);
  			~I2PClientTunnel () {}
  
  			void Start ();
  			void Stop ();
  
  			const char* GetName() { return m_Name.c_str (); }
  
  		private:
  
  			std::shared_ptr<const Address> GetAddress ();
  
  		private:
  
  			std::string m_Name, m_Destination;
  			std::shared_ptr<const Address> m_Address;
  			int m_DestinationPort;
  	};
  
  
  	/** 2 minute timeout for udp sessions */
  	const uint64_t I2P_UDP_SESSION_TIMEOUT = 1000 * 60 * 2;
  	const uint64_t I2P_UDP_REPLIABLE_DATAGRAM_INTERVAL = 100; // in milliseconds	
  	
  	/** max size for i2p udp */
  	const size_t I2P_UDP_MAX_MTU = 64*1024;
  
  	struct UDPSession
  	{
  		i2p::datagram::DatagramDestination * m_Destination;
  		boost::asio::ip::udp::socket IPSocket;
  		i2p::data::IdentHash Identity;
  		boost::asio::ip::udp::endpoint FromEndpoint;
  		boost::asio::ip::udp::endpoint SendEndpoint;
  		uint64_t LastActivity;
  
  		uint16_t LocalPort;
  		uint16_t RemotePort;
  
  		uint8_t m_Buffer[I2P_UDP_MAX_MTU];
  
  		UDPSession(boost::asio::ip::udp::endpoint localEndpoint,
  			const std::shared_ptr<i2p::client::ClientDestination> & localDestination,
  			boost::asio::ip::udp::endpoint remote, const i2p::data::IdentHash * ident,
  			uint16_t ourPort, uint16_t theirPort);
  		void HandleReceived(const boost::system::error_code & ecode, std::size_t len);
  		void Receive();
  	};
  
  
  	/** read only info about a datagram session */
  	struct DatagramSessionInfo
  	{
  		/** the name of this forward */
  		std::string Name;
  		/** ident hash of local destination */
  		std::shared_ptr<const i2p::data::IdentHash> LocalIdent;
  		/** ident hash of remote destination */
  		std::shared_ptr<const i2p::data::IdentHash> RemoteIdent;
  		/** ident hash of IBGW in use currently in this session or nullptr if none is set */
  		std::shared_ptr<const i2p::data::IdentHash> CurrentIBGW;
  		/** ident hash of OBEP in use for this session or nullptr if none is set */
  		std::shared_ptr<const i2p::data::IdentHash> CurrentOBEP;
  		/** i2p router's udp endpoint */
  		boost::asio::ip::udp::endpoint LocalEndpoint;
  		/** client's udp endpoint */
  		boost::asio::ip::udp::endpoint RemoteEndpoint;
  		/** how long has this converstation been idle in ms */
  		uint64_t idle;
  	};
  
  	typedef std::shared_ptr<UDPSession> UDPSessionPtr;
  
  	/** server side udp tunnel, many i2p inbound to 1 ip outbound */
  	class I2PUDPServerTunnel
  	{
  		public:
  
  			I2PUDPServerTunnel(const std::string & name,
  				std::shared_ptr<i2p::client::ClientDestination> localDestination,
  				boost::asio::ip::address localAddress,
  				boost::asio::ip::udp::endpoint forwardTo, uint16_t port, bool gzip);
  			~I2PUDPServerTunnel();
  			/** expire stale udp conversations */
  			void ExpireStale(const uint64_t delta=I2P_UDP_SESSION_TIMEOUT);
  			void Start();
  			const char * GetName() const { return m_Name.c_str(); }
  			std::vector<std::shared_ptr<DatagramSessionInfo> > GetSessions();
  			std::shared_ptr<ClientDestination> GetLocalDestination () const { return m_LocalDest; }
  
  			void SetUniqueLocal(bool isUniqueLocal = true) { m_IsUniqueLocal = isUniqueLocal; }
  
  		private:
  
  			void HandleRecvFromI2P(const i2p::data::IdentityEx& from, uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len);
  			void HandleRecvFromI2PRaw (uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len);
  			UDPSessionPtr ObtainUDPSession(const i2p::data::IdentityEx& from, uint16_t localPort, uint16_t remotePort);
  
  		private:
  
  			bool m_IsUniqueLocal;
  			const std::string m_Name;
  			boost::asio::ip::address m_LocalAddress;
  			boost::asio::ip::udp::endpoint m_RemoteEndpoint;
  			std::mutex m_SessionsMutex;
  			std::vector<UDPSessionPtr> m_Sessions;
  			std::shared_ptr<i2p::client::ClientDestination> m_LocalDest;
  			UDPSessionPtr m_LastSession;
  	};
  
  	class I2PUDPClientTunnel
  	{
  		public:
  
  			I2PUDPClientTunnel(const std::string & name, const std::string &remoteDest,
  				boost::asio::ip::udp::endpoint localEndpoint, std::shared_ptr<i2p::client::ClientDestination> localDestination,
  				uint16_t remotePort, bool gzip);
  			~I2PUDPClientTunnel();
  			void Start();
  			const char * GetName() const { return m_Name.c_str(); }
  			std::vector<std::shared_ptr<DatagramSessionInfo> > GetSessions();
  
  			bool IsLocalDestination(const i2p::data::IdentHash & destination) const { return destination == m_LocalDest->GetIdentHash(); }
  
  			std::shared_ptr<ClientDestination> GetLocalDestination () const { return m_LocalDest; }
  			void ExpireStale(const uint64_t delta=I2P_UDP_SESSION_TIMEOUT);
  
  		private:
  
  			typedef std::pair<boost::asio::ip::udp::endpoint, uint64_t> UDPConvo;
  			void RecvFromLocal();
  			void HandleRecvFromLocal(const boost::system::error_code & e, std::size_t transferred);
  			void HandleRecvFromI2P(const i2p::data::IdentityEx& from, uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len);
  			void HandleRecvFromI2PRaw(uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len);
  			void TryResolving();
  
  		private:
  			
  			const std::string m_Name;
  			std::mutex m_SessionsMutex;
  			std::unordered_map<uint16_t, std::shared_ptr<UDPConvo> > m_Sessions; // maps i2p port -> local udp convo
  			const std::string m_RemoteDest;
  			std::shared_ptr<i2p::client::ClientDestination> m_LocalDest;
  			const boost::asio::ip::udp::endpoint m_LocalEndpoint;
  			i2p::data::IdentHash * m_RemoteIdent;
  			std::thread * m_ResolveThread;
  			boost::asio::ip::udp::socket m_LocalSocket;
  			boost::asio::ip::udp::endpoint m_RecvEndpoint;
  			uint8_t m_RecvBuff[I2P_UDP_MAX_MTU];
  			uint16_t RemotePort, m_LastPort;
  			bool m_cancel_resolve;
  			std::shared_ptr<UDPConvo> m_LastSession;
  	};
  
  	class I2PServerTunnel: public I2PService
  	{
  		public:
  
  			I2PServerTunnel (const std::string& name, const std::string& address, int port,
  				std::shared_ptr<ClientDestination> localDestination, int inport = 0, bool gzip = true);
  
  			void Start ();
  			void Stop ();
  
  			void SetAccessList (const std::set<i2p::data::IdentHash>& accessList);
  
  			void SetUniqueLocal (bool isUniqueLocal) { m_IsUniqueLocal = isUniqueLocal; }
  			bool IsUniqueLocal () const { return m_IsUniqueLocal; }
  
  			const std::string& GetAddress() const { return m_Address; }
  			int GetPort () const { return m_Port; };
  			uint16_t GetLocalPort () const { return m_PortDestination->GetLocalPort (); };
  			const boost::asio::ip::tcp::endpoint& GetEndpoint () const { return m_Endpoint; }
  
  			const char* GetName() { return m_Name.c_str (); }
  
  		private:
  
  			void HandleResolve (const boost::system::error_code& ecode, boost::asio::ip::tcp::resolver::iterator it,
  				std::shared_ptr<boost::asio::ip::tcp::resolver> resolver);
  
  			void Accept ();
  			void HandleAccept (std::shared_ptr<i2p::stream::Stream> stream);
  			virtual std::shared_ptr<I2PTunnelConnection> CreateI2PConnection (std::shared_ptr<i2p::stream::Stream> stream);
  
  		private:
  
  			bool m_IsUniqueLocal;
  			std::string m_Name, m_Address;
  			int m_Port;
  			boost::asio::ip::tcp::endpoint m_Endpoint;
  			std::shared_ptr<i2p::stream::StreamingDestination> m_PortDestination;
  			std::set<i2p::data::IdentHash> m_AccessList;
  			bool m_IsAccessList;
  	};
  
  	class I2PServerTunnelHTTP: public I2PServerTunnel
  	{
  		public:
  
  			I2PServerTunnelHTTP (const std::string& name, const std::string& address, int port,
  				std::shared_ptr<ClientDestination> localDestination, const std::string& host,
  				int inport = 0, bool gzip = true);
  
  		private:
  
  			std::shared_ptr<I2PTunnelConnection> CreateI2PConnection (std::shared_ptr<i2p::stream::Stream> stream);
  
  		private:
  
  			std::string m_Host;
  	};
  
  	class I2PServerTunnelIRC: public I2PServerTunnel
  	{
  		public:
  
  			I2PServerTunnelIRC (const std::string& name, const std::string& address, int port,
  				std::shared_ptr<ClientDestination> localDestination, const std::string& webircpass,
  				int inport = 0, bool gzip = true);
  
  		private:
  
  			std::shared_ptr<I2PTunnelConnection> CreateI2PConnection (std::shared_ptr<i2p::stream::Stream> stream);
  
  		private:
  
  			std::string m_WebircPass;
  	};
  }
  }
  
  #endif
  