i2pd/I2PTunnel.cpp

#include <cassert>
#include "Base.h"
#include "Log.h"
#include "Destination.h"
#include "ClientContext.h"
#include "I2PTunnel.h"

namespace i2p
{
namespace client
{

	/** set standard socket options */
	static void I2PTunnelSetSocketOptions(std::shared_ptr<boost::asio::ip::tcp::socket> socket)
	{
		if (socket && socket->is_open())
		{			 
			boost::asio::socket_base::receive_buffer_size option(I2P_TUNNEL_CONNECTION_BUFFER_SIZE);
			socket->set_option(option);
		}
	}
	
	I2PTunnelConnection::I2PTunnelConnection (I2PService * owner, std::shared_ptr<boost::asio::ip::tcp::socket> socket,
		std::shared_ptr<const i2p::data::LeaseSet> leaseSet, int port): 
		I2PServiceHandler(owner), m_Socket (socket), m_RemoteEndpoint (socket->remote_endpoint ()),
		m_IsQuiet (true)
	{
		m_Stream = GetOwner()->GetLocalDestination ()->CreateStream (leaseSet, port);
	}	

	I2PTunnelConnection::I2PTunnelConnection (I2PService * owner,
	    std::shared_ptr<boost::asio::ip::tcp::socket> socket, std::shared_ptr<i2p::stream::Stream> stream):
		I2PServiceHandler(owner), m_Socket (socket), m_Stream (stream),
		m_RemoteEndpoint (socket->remote_endpoint ()), m_IsQuiet (true)
	{
	}

	I2PTunnelConnection::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):
		I2PServiceHandler(owner), m_Socket (socket), m_Stream (stream),
		m_RemoteEndpoint (target), m_IsQuiet (quiet)
	{
	}

	I2PTunnelConnection::~I2PTunnelConnection ()
	{
	}	
  
	void I2PTunnelConnection::I2PConnect (const uint8_t * msg, size_t len)
	{
		if (m_Stream)
		{
			if (msg)
				m_Stream->Send (msg, len); // connect and send
			else	
				m_Stream->Send (m_Buffer, 0); // connect
		}
		StreamReceive ();
		Receive ();
	}
		
	void I2PTunnelConnection::Connect ()
	{
		I2PTunnelSetSocketOptions(m_Socket);
		if (m_Socket) {
#ifdef __linux__ 			
			// bind to 127.x.x.x address 
			// where x.x.x are first three bytes from ident

			if (m_RemoteEndpoint.address ().is_v4 () &&
				m_RemoteEndpoint.address ().to_v4 ().to_bytes ()[0] == 127)
			{
				m_Socket->open (boost::asio::ip::tcp::v4 ());
				boost::asio::ip::address_v4::bytes_type bytes;
				const uint8_t * ident = m_Stream->GetRemoteIdentity ()->GetIdentHash ();
				bytes[0] = 127;
				memcpy (bytes.data ()+1, ident, 3);
				boost::asio::ip::address ourIP = boost::asio::ip::address_v4 (bytes);
				m_Socket->bind (boost::asio::ip::tcp::endpoint (ourIP, 0));
			}
#endif
 			m_Socket->async_connect (m_RemoteEndpoint, std::bind (&I2PTunnelConnection::HandleConnect,
				shared_from_this (), std::placeholders::_1));
		}
	}	
		
	void I2PTunnelConnection::Terminate ()
	{
		if (Kill()) return;
		if (m_Stream)
		{
			m_Stream->Close ();
			m_Stream.reset ();
		}	
		m_Socket->close ();
		Done(shared_from_this ());
	}			

	void I2PTunnelConnection::Receive ()
	{
		m_Socket->async_read_some (boost::asio::buffer(m_Buffer, I2P_TUNNEL_CONNECTION_BUFFER_SIZE),                
			std::bind(&I2PTunnelConnection::HandleReceived, shared_from_this (), 
			std::placeholders::_1, std::placeholders::_2));
	}	
	
	void I2PTunnelConnection::HandleReceived (const boost::system::error_code& ecode, std::size_t bytes_transferred)
	{
		if (ecode)
		{
			LogPrint (eLogError, "I2PTunnel: read error: ", ecode.message ());
			if (ecode != boost::asio::error::operation_aborted)
				Terminate ();
		}
		else
		{	
			if (m_Stream)
			{	
				auto s = shared_from_this ();
				m_Stream->AsyncSend (m_Buffer, bytes_transferred,
					[s](const boost::system::error_code& ecode)
				    {
						if (!ecode)
							s->Receive ();
						else
							s->Terminate ();
					});
			}	
		}
	}	

	void I2PTunnelConnection::HandleWrite (const boost::system::error_code& ecode)
	{
		if (ecode)
		{
			LogPrint (eLogError, "I2PTunnel: write error: ", ecode.message ());
			if (ecode != boost::asio::error::operation_aborted)
				Terminate ();
		}
		else
			StreamReceive ();
	}

	void I2PTunnelConnection::StreamReceive ()
	{
		if (m_Stream)
		{
			if (m_Stream->GetStatus () == i2p::stream::eStreamStatusNew ||
			    m_Stream->GetStatus () == i2p::stream::eStreamStatusOpen) // regular
			{	
				m_Stream->AsyncReceive (boost::asio::buffer (m_StreamBuffer, I2P_TUNNEL_CONNECTION_BUFFER_SIZE),
					std::bind (&I2PTunnelConnection::HandleStreamReceive, shared_from_this (),
						std::placeholders::_1, std::placeholders::_2),
					I2P_TUNNEL_CONNECTION_MAX_IDLE);
			}	
			else // closed by peer
			{
				// get remaning data
				auto len = m_Stream->ReadSome (m_StreamBuffer, I2P_TUNNEL_CONNECTION_BUFFER_SIZE);
				if (len > 0) // still some data
					Write (m_StreamBuffer, len);
				else // no more data
					Terminate (); 
			}		
		}	
	}	

	void I2PTunnelConnection::HandleStreamReceive (const boost::system::error_code& ecode, std::size_t bytes_transferred)
	{
		if (ecode)
		{
			LogPrint (eLogError, "I2PTunnel: stream read error: ", ecode.message ());
			if (ecode != boost::asio::error::operation_aborted)
			{
				if (bytes_transferred > 0)
					Write (m_StreamBuffer, bytes_transferred); // postpone termination
				else	
					Terminate ();
			}	
		}
		else
			Write (m_StreamBuffer, bytes_transferred);
	}

	void I2PTunnelConnection::Write (const uint8_t * buf, size_t len)
	{
		boost::asio::async_write (*m_Socket, boost::asio::buffer (buf, len), boost::asio::transfer_all (),
        	std::bind (&I2PTunnelConnection::HandleWrite, shared_from_this (), std::placeholders::_1));
	}

	void I2PTunnelConnection::HandleConnect (const boost::system::error_code& ecode)
	{
		if (ecode)
		{
			LogPrint (eLogError, "I2PTunnel: connect error: ", ecode.message ());
			Terminate ();
		}
		else
		{
			LogPrint (eLogDebug, "I2PTunnel: connected");
			if (m_IsQuiet)
				StreamReceive ();
			else
			{
				// send destination first like received from I2P
				std::string dest = m_Stream->GetRemoteIdentity ()->ToBase64 ();
				dest += "\n";
				memcpy (m_StreamBuffer, dest.c_str (), dest.size ());
				HandleStreamReceive (boost::system::error_code (), dest.size ());
			}	
			Receive ();	
		}
	}

	I2PTunnelConnectionHTTP::I2PTunnelConnectionHTTP (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):
		I2PTunnelConnection (owner, stream, socket, target), m_Host (host), m_HeaderSent (false), m_From (stream->GetRemoteIdentity ())
	{
	}

	void I2PTunnelConnectionHTTP::Write (const uint8_t * buf, size_t len)
	{
		if (m_HeaderSent)
			I2PTunnelConnection::Write (buf, len);
		else
		{	
			m_InHeader.clear ();
			m_InHeader.write ((const char *)buf, len);
			std::string line;
			bool endOfHeader = false;
			while (!endOfHeader)
			{
				std::getline(m_InHeader, line);
				if (!m_InHeader.fail ())
				{
					if (line == "\r") endOfHeader = true;
					else
					{	
						if (line.find ("Host:") != std::string::npos)
							m_OutHeader << "Host: " << m_Host << "\r\n";
						else
							m_OutHeader << line << "\n";
					}	
				}
				else
					break;
			}
			// add X-I2P fields
			if (m_From)
			{
				m_OutHeader << X_I2P_DEST_B32 << ": " << context.GetAddressBook ().ToAddress(m_From->GetIdentHash ()) << "\r\n";
				m_OutHeader << X_I2P_DEST_HASH << ": " << m_From->GetIdentHash ().ToBase64 () << "\r\n";
				m_OutHeader << X_I2P_DEST_B64 << ": " << m_From->ToBase64 () << "\r\n";
			}

			if (endOfHeader)
			{
				m_OutHeader << "\r\n"; // end of header
				m_OutHeader << m_InHeader.str ().substr (m_InHeader.tellg ()); // data right after header
				m_HeaderSent = true;
				I2PTunnelConnection::Write ((uint8_t *)m_OutHeader.str ().c_str (), m_OutHeader.str ().length ());
			}
		}	
	}

	I2PTunnelConnectionIRC::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& webircpass):
        I2PTunnelConnection (owner, stream, socket, target), m_From (stream->GetRemoteIdentity ()), 
        m_NeedsWebIrc (webircpass.length() ? true : false), m_WebircPass (webircpass)
    {
    }

    void I2PTunnelConnectionIRC::Write (const uint8_t * buf, size_t len)
    {
    	if (m_NeedsWebIrc) {
        	m_NeedsWebIrc = false;
        	m_OutPacket.str ("");
            m_OutPacket << "WEBIRC " << this->m_WebircPass << " cgiirc " << context.GetAddressBook ().ToAddress (m_From->GetIdentHash ()) << " 127.0.0.1\n";
            I2PTunnelConnection::Write ((uint8_t *)m_OutPacket.str ().c_str (), m_OutPacket.str ().length ());
        }

    	std::string line;
        m_OutPacket.str ("");
        m_InPacket.clear ();
        m_InPacket.write ((const char *)buf, len);
        
        while (!m_InPacket.eof () && !m_InPacket.fail ())
        {
            std::getline (m_InPacket, line);
            if (line.length () == 0 && m_InPacket.eof ()) {
            	m_InPacket.str ("");
            }
            auto pos = line.find ("USER");
            if (pos != std::string::npos && pos == 0)
            {
                pos = line.find (" ");
                pos++;
                pos = line.find (" ", pos);
                pos++;
                auto nextpos = line.find (" ", pos);
                m_OutPacket << line.substr (0, pos);
                m_OutPacket << context.GetAddressBook ().ToAddress (m_From->GetIdentHash ());
                m_OutPacket << line.substr (nextpos) << '\n';
            } else {
                m_OutPacket << line << '\n';
            }
        }
        I2PTunnelConnection::Write ((uint8_t *)m_OutPacket.str ().c_str (), m_OutPacket.str ().length ());
    }


	/* This handler tries to stablish a connection with the desired server and dies if it fails to do so */
	class I2PClientTunnelHandler: public I2PServiceHandler, public std::enable_shared_from_this<I2PClientTunnelHandler>
	{
		public:
			I2PClientTunnelHandler (I2PClientTunnel * parent, i2p::data::IdentHash destination,
				int destinationPort, std::shared_ptr<boost::asio::ip::tcp::socket> socket):
				I2PServiceHandler(parent), m_DestinationIdentHash(destination), 
				m_DestinationPort (destinationPort), m_Socket(socket) {};
			void Handle();
			void Terminate();
		private:
			void HandleStreamRequestComplete (std::shared_ptr<i2p::stream::Stream> stream);
			i2p::data::IdentHash m_DestinationIdentHash;
			int m_DestinationPort;
			std::shared_ptr<boost::asio::ip::tcp::socket> m_Socket;
	};

	void I2PClientTunnelHandler::Handle()
	{
		GetOwner()->GetLocalDestination ()->CreateStream ( 
			std::bind (&I2PClientTunnelHandler::HandleStreamRequestComplete, shared_from_this(), std::placeholders::_1), 
			m_DestinationIdentHash, m_DestinationPort);
	}

	void I2PClientTunnelHandler::HandleStreamRequestComplete (std::shared_ptr<i2p::stream::Stream> stream)
	{
		if (stream)
		{
			if (Kill()) return;
			LogPrint (eLogDebug, "I2PTunnel: new connection");
			auto connection = std::make_shared<I2PTunnelConnection>(GetOwner(), m_Socket, stream);
			GetOwner()->AddHandler (connection);
			connection->I2PConnect ();
			Done(shared_from_this());
		}
		else
		{
			LogPrint (eLogError, "I2PTunnel: Client Tunnel Issue when creating the stream, check the previous warnings for more info.");
			Terminate();
		}
	}

	void I2PClientTunnelHandler::Terminate()
	{
		if (Kill()) return;
		if (m_Socket)
		{
			m_Socket->close();
			m_Socket = nullptr;
		}
		Done(shared_from_this());
	}

	I2PClientTunnel::I2PClientTunnel (const std::string& name, const std::string& destination, 
	    const std::string& address, int port, std::shared_ptr<ClientDestination> localDestination, int destinationPort): 
		TCPIPAcceptor (address, port, localDestination), m_Name (name), m_Destination (destination), 
		m_DestinationIdentHash (nullptr), m_DestinationPort (destinationPort) 
	{
	}	

	void I2PClientTunnel::Start ()
	{
		TCPIPAcceptor::Start ();
		GetIdentHash();
	}

	void I2PClientTunnel::Stop ()
	{
		TCPIPAcceptor::Stop();
		auto *originalIdentHash = m_DestinationIdentHash;
		m_DestinationIdentHash = nullptr;
		delete originalIdentHash;
	}

	/* HACK: maybe we should create a caching IdentHash provider in AddressBook */
	const i2p::data::IdentHash * I2PClientTunnel::GetIdentHash ()
	{
		if (!m_DestinationIdentHash)
		{
			i2p::data::IdentHash identHash;
			if (i2p::client::context.GetAddressBook ().GetIdentHash (m_Destination, identHash))
				m_DestinationIdentHash = new i2p::data::IdentHash (identHash);
			else
				LogPrint (eLogWarning, "I2PTunnel: Remote destination ", m_Destination, " not found");
		}
		return m_DestinationIdentHash;
	}

	std::shared_ptr<I2PServiceHandler> I2PClientTunnel::CreateHandler(std::shared_ptr<boost::asio::ip::tcp::socket> socket)
	{
		const i2p::data::IdentHash *identHash = GetIdentHash();
		if (identHash)
			return  std::make_shared<I2PClientTunnelHandler>(this, *identHash, m_DestinationPort, socket);
		else
			return nullptr;
	}

	I2PServerTunnel::I2PServerTunnel (const std::string& name, const std::string& address, 
	    int port, std::shared_ptr<ClientDestination> localDestination, int inport, bool gzip): 
		I2PService (localDestination), m_Name (name), m_Address (address), m_Port (port), m_IsAccessList (false)
	{
		m_PortDestination = localDestination->CreateStreamingDestination (inport > 0 ? inport : port, gzip);
	}

	void I2PServerTunnel::Start ()
	{
		m_Endpoint.port (m_Port);	
		boost::system::error_code ec;
		auto addr = boost::asio::ip::address::from_string (m_Address, ec);
		if (!ec)	
		{
			m_Endpoint.address (addr);
			Accept ();
		}
		else
		{
			auto resolver = std::make_shared<boost::asio::ip::tcp::resolver>(GetService ());
			resolver->async_resolve (boost::asio::ip::tcp::resolver::query (m_Address, ""), 
				std::bind (&I2PServerTunnel::HandleResolve, this, 
					std::placeholders::_1, std::placeholders::_2, resolver));
		}	
	}

	void I2PServerTunnel::Stop ()
	{
		ClearHandlers ();
	}	

	void I2PServerTunnel::HandleResolve (const boost::system::error_code& ecode, boost::asio::ip::tcp::resolver::iterator it, 
		std::shared_ptr<boost::asio::ip::tcp::resolver> resolver)
	{	
		if (!ecode)
		{	
			auto addr = (*it).endpoint ().address ();
			LogPrint (eLogInfo, "I2PTunnel: server tunnel ", (*it).host_name (), " has been resolved to ", addr);
			m_Endpoint.address (addr);
			Accept ();	
		}	
		else
			LogPrint (eLogError, "I2PTunnel: Unable to resolve server tunnel address: ", ecode.message ());
	}

	void I2PServerTunnel::SetAccessList (const std::set<i2p::data::IdentHash>& accessList)
	{
		m_AccessList = accessList;
		m_IsAccessList = true;		
	}

	void I2PServerTunnel::Accept ()
	{
		if (m_PortDestination)
			m_PortDestination->SetAcceptor (std::bind (&I2PServerTunnel::HandleAccept, this, std::placeholders::_1));

		auto localDestination = GetLocalDestination ();	
		if (localDestination)
		{
			if (!localDestination->IsAcceptingStreams ()) // set it as default if not set yet
				localDestination->AcceptStreams (std::bind (&I2PServerTunnel::HandleAccept, this, std::placeholders::_1));
		}
		else
			LogPrint (eLogError, "I2PTunnel: Local destination not set for server tunnel");
	}

	void I2PServerTunnel::HandleAccept (std::shared_ptr<i2p::stream::Stream> stream)
	{
		if (stream)
		{	
			if (m_IsAccessList)
			{
				if (!m_AccessList.count (stream->GetRemoteIdentity ()->GetIdentHash ()))
				{
					LogPrint (eLogWarning, "I2PTunnel: Address ", stream->GetRemoteIdentity ()->GetIdentHash ().ToBase32 (), " is not in white list. Incoming connection dropped");
					stream->Close ();
					return;
				}
			}
			CreateI2PConnection (stream);
		}	
	}

	void I2PServerTunnel::CreateI2PConnection (std::shared_ptr<i2p::stream::Stream> stream)
	{
		auto conn = std::make_shared<I2PTunnelConnection> (this, stream, std::make_shared<boost::asio::ip::tcp::socket> (GetService ()), GetEndpoint ());
		AddHandler (conn);
		conn->Connect ();
	}

	I2PServerTunnelHTTP::I2PServerTunnelHTTP (const std::string& name, const std::string& address, 
	    int port, std::shared_ptr<ClientDestination> localDestination, 
	    const std::string& host, int inport, bool gzip):
		I2PServerTunnel (name, address, port, localDestination, inport, gzip), 
		m_Host (host.length () > 0 ? host : address)
	{
	}

	void I2PServerTunnelHTTP::CreateI2PConnection (std::shared_ptr<i2p::stream::Stream> stream)
	{
		auto conn = std::make_shared<I2PTunnelConnectionHTTP> (this, stream, 
			std::make_shared<boost::asio::ip::tcp::socket> (GetService ()), GetEndpoint (), m_Host);
		AddHandler (conn);
		conn->Connect ();
	}

    I2PServerTunnelIRC::I2PServerTunnelIRC (const std::string& name, const std::string& address, 
        int port, std::shared_ptr<ClientDestination> localDestination, 
        const std::string& webircpass, int inport, bool gzip):
        I2PServerTunnel (name, address, port, localDestination, inport, gzip),
        m_WebircPass (webircpass)
    {
    }

    void I2PServerTunnelIRC::CreateI2PConnection (std::shared_ptr<i2p::stream::Stream> stream)
    {
	    auto conn = std::make_shared<I2PTunnelConnectionIRC> (this, stream, std::make_shared<boost::asio::ip::tcp::socket> (GetService ()), GetEndpoint (), this->m_WebircPass);
	    AddHandler (conn);
        conn->Connect ();
    }

  void I2PUDPServerTunnel::HandleRecvFromI2P(const i2p::data::IdentityEx& from, uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len)
  {
    std::lock_guard<std::mutex> lock(m_SessionsMutex);
    auto session = ObtainUDPSession(from, toPort, fromPort);
    session->IPSocket.send_to(boost::asio::buffer(buf, len), m_Endpoint);
    session->LastActivity = i2p::util::GetMillisecondsSinceEpoch();
    
  }

  void I2PUDPServerTunnel::ExpireStale(const uint64_t delta) {
    std::lock_guard<std::mutex> lock(m_SessionsMutex);
    uint64_t now = i2p::util::GetMillisecondsSinceEpoch();
    std::remove_if(m_Sessions.begin(), m_Sessions.end(), [now, delta](const UDPSession * u) -> bool {
      return now - u->LastActivity >= delta;
    });
  }
  
  UDPSession * I2PUDPServerTunnel::ObtainUDPSession(const i2p::data::IdentityEx& from, uint16_t localPort, uint16_t remotePort)
  {
    auto ih = from.GetIdentHash();
    for ( UDPSession * s : m_Sessions ) {
      if ( s->Identity == ih) {
        /** found existing */
        LogPrint(eLogDebug, "UDPServer: found session ", s->IPSocket.local_endpoint(), " ", ih.ToBase32());
        return s;
      }
    }
    /** create new */
    boost::asio::ip::udp::endpoint ep(boost::asio::ip::address::from_string("127.0.0.1"), 0);
    m_Sessions.push_back(new UDPSession(ep, m_LocalDest, m_Endpoint, ih, localPort, remotePort));
    return m_Sessions.back();
  }

  UDPSession::UDPSession(boost::asio::ip::udp::endpoint localEndpoint, const std::shared_ptr<i2p::client::ClientDestination> & localDestination, boost::asio::ip::udp::endpoint endpoint, const i2p::data::IdentHash to, uint16_t ourPort, uint16_t theirPort) :
    m_Destination(localDestination->GetDatagramDestination()),
    m_Service(localDestination->GetService()),
    IPSocket(localDestination->GetService(), localEndpoint),
    Identity(to),
    SendEndpoint(endpoint),
    LastActivity(i2p::util::GetMillisecondsSinceEpoch()),
    LocalPort(ourPort),
    RemotePort(theirPort)
  {
    Receive();
  }


  void UDPSession::Receive() {
    LogPrint(eLogDebug, "UDPSession: Receive");
    IPSocket.async_receive_from(boost::asio::buffer(m_Buffer, I2P_UDP_MAX_MTU), FromEndpoint, std::bind(&UDPSession::HandleReceived, this, std::placeholders::_1, std::placeholders::_2));
  }
  
  void UDPSession::HandleReceived(const boost::system::error_code & ecode, std::size_t len)
  {
    if(!ecode) {
      LogPrint(eLogDebug, "UDPSession: forward ", len, "B from ", FromEndpoint);
      LastActivity = i2p::util::GetMillisecondsSinceEpoch();
      uint8_t * data = new uint8_t[len];
      memcpy(data, m_Buffer, len);
      m_Service.post([&,len, data] () {
          m_Destination->SendDatagramTo(data, len, Identity, 0, 0);
        delete [] data;
      });
      
      Receive();
    } else {
      LogPrint(eLogError, "UDPSession: ", ecode.message());
    }
  }

  
  
  I2PUDPServerTunnel::I2PUDPServerTunnel(const std::string & name, std::shared_ptr<i2p::client::ClientDestination> localDestination, boost::asio::ip::udp::endpoint forwardTo, uint16_t port) :
    LocalPort(port),
    m_Endpoint(forwardTo)
  {
    m_LocalDest = localDestination;
    m_LocalDest->Start();
    auto dgram = m_LocalDest->CreateDatagramDestination();
    dgram->SetReceiver(std::bind(&I2PUDPServerTunnel::HandleRecvFromI2P, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, std::placeholders::_4, std::placeholders::_5));
  }

  I2PUDPServerTunnel::~I2PUDPServerTunnel()
  {
    auto dgram = m_LocalDest->GetDatagramDestination();
    if (dgram) {
      dgram->ResetReceiver();
    }
    LogPrint(eLogInfo, "UDPServer: done");
  }

  void I2PUDPServerTunnel::Start() {
    m_LocalDest->Start();
  }
  
  I2PUDPClientTunnel::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) :
    m_Session(nullptr),
    m_RemoteDest(remoteDest),
    m_RemoteIdent(nullptr),
    m_LocalDest(localDestination),
    m_LocalEndpoint(localEndpoint),
    m_ResolveThread(nullptr),
    LocalPort(localEndpoint.port()),
    RemotePort(remotePort),
    m_cancel_resolve(false)
  {
    auto dgram = m_LocalDest->CreateDatagramDestination();
    dgram->SetReceiver(std::bind(&I2PUDPClientTunnel::HandleRecvFromI2P, this,
                                 std::placeholders::_1, std::placeholders::_2,
                                 std::placeholders::_3, std::placeholders::_4,
                                 std::placeholders::_5));   
  }

  
  
  void I2PUDPClientTunnel::Start() {
    m_LocalDest->Start();
    if (m_ResolveThread == nullptr)
      m_ResolveThread = new std::thread(std::bind(&I2PUDPClientTunnel::TryResolving, this));
  }

  void I2PUDPClientTunnel::TryResolving() {
    LogPrint(eLogInfo, "UDP Tunnel: Trying to resolve ", m_RemoteDest);
    m_RemoteIdent = new i2p::data::IdentHash;
    m_RemoteIdent->Fill(0);

    while(!context.GetAddressBook().GetIdentHash(m_RemoteDest, *m_RemoteIdent) && !m_cancel_resolve) {
      LogPrint(eLogWarning, "UDP Tunnel: failed to lookup ", m_RemoteDest);
      std::this_thread::sleep_for(std::chrono::seconds(1));
    }
    if(m_cancel_resolve) {
      LogPrint(eLogError, "UDP Tunnel: lookup of ", m_RemoteDest, " was cancelled");
      return;
    }
    LogPrint(eLogInfo, "UDP Tunnel: resolved ", m_RemoteDest, " to ", m_RemoteIdent->ToBase32());
    // delete existing session
    if(m_Session) delete m_Session;
    boost::asio::ip::udp::endpoint ep(boost::asio::ip::address::from_string("127.0.0.1"), 0);
    m_Session = new UDPSession(m_LocalEndpoint, m_LocalDest, ep, *m_RemoteIdent, LocalPort, RemotePort);
  }

  void I2PUDPClientTunnel::HandleRecvFromI2P(const i2p::data::IdentityEx& from, uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len)
  {
    if(m_RemoteIdent && from.GetIdentHash() == *m_RemoteIdent) {
      // address match
      if(m_Session) {
        // tell session
        LogPrint(eLogDebug, "UDP Client: got ", len, "B from ", from.GetIdentHash().ToBase32());
        m_Session->IPSocket.send_to(boost::asio::buffer(buf, len), m_Session->FromEndpoint);
      } else {
        LogPrint(eLogWarning, "UDP Client: no session");
      }
    } else {
      LogPrint(eLogWarning, "UDP Client: unwarrented traffic from ", from.GetIdentHash().ToBase32());
    }
  }
  
  I2PUDPClientTunnel::~I2PUDPClientTunnel() {
    auto dgram = m_LocalDest->GetDatagramDestination();
    if (dgram) {
      dgram->ResetReceiver();
    }
    if (m_Session) delete m_Session;
    m_cancel_resolve = true;
    if(m_ResolveThread) {
      m_ResolveThread->join();
      delete m_ResolveThread;
      m_ResolveThread = nullptr;
    }
    if (m_RemoteIdent) delete m_RemoteIdent;
  }
}		
}