/*
* Copyright (c) 2013-2022, 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
*/

#include <cassert>
#include <boost/algorithm/string.hpp>
#include "Base.h"
#include "Log.h"
#include "Destination.h"
#include "ClientContext.h"
#include "I2PTunnel.h"
#include "util.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();
        }

        static boost::asio::ip::address GetLoopbackAddressFor(const i2p::data::IdentHash &addr) {
            boost::asio::ip::address_v4::bytes_type bytes;
            const uint8_t *ident = addr;
            bytes[0] = 127;
            memcpy(bytes.data() + 1, ident, 3);
            boost::asio::ip::address ourIP = boost::asio::ip::address_v4(bytes);
            return ourIP;
        }

#ifdef __linux__
        static void MapToLoopback(const std::shared_ptr<boost::asio::ip::tcp::socket> & sock, const i2p::data::IdentHash & addr)
        {
            // bind to 127.x.x.x address
            // where x.x.x are first three bytes from ident
            auto ourIP = GetLoopbackAddressFor(addr);
            boost::system::error_code ec;
            sock->bind (boost::asio::ip::tcp::endpoint (ourIP, 0), ec);
            if (ec)
                LogPrint (eLogError, "I2PTunnel: Can't bind ourIP to ", ourIP.to_string (), ": ", ec.message ());

        }
#endif

        void I2PTunnelConnection::Connect(bool isUniqueLocal) {
            I2PTunnelSetSocketOptions(m_Socket);
            if (m_Socket) {
#ifdef __linux__
                if (isUniqueLocal && m_RemoteEndpoint.address ().is_v4 () &&
                    m_RemoteEndpoint.address ().to_v4 ().to_bytes ()[0] == 127)
                {
                    m_Socket->open (boost::asio::ip::tcp::v4 ());
                    auto ident = m_Stream->GetRemoteIdentity()->GetIdentHash();
                    MapToLoopback(m_Socket, ident);
                }
#endif
                m_Socket->async_connect(m_RemoteEndpoint, std::bind(&I2PTunnelConnection::HandleConnect,
                                                                    shared_from_this(), std::placeholders::_1));
            }
        }

        void I2PTunnelConnection::Connect(const boost::asio::ip::address &localAddress) {
            if (m_Socket) {
                if (m_RemoteEndpoint.address().is_v6())
                    m_Socket->open(boost::asio::ip::tcp::v6());
                else
                    m_Socket->open(boost::asio::ip::tcp::v4());
                boost::system::error_code ec;
                m_Socket->bind(boost::asio::ip::tcp::endpoint(localAddress, 0), ec);
                if (ec)
                    LogPrint(eLogError, "I2PTunnel: Can't bind to ", localAddress.to_string(), ": ", ec.message());
            }
            Connect(false);
        }

        void I2PTunnelConnection::Terminate() {
            if (Kill()) return;
            if (m_Stream) {
                m_Stream->Close();
                m_Stream.reset();
            }
            boost::system::error_code ec;
            m_Socket->shutdown(boost::asio::ip::tcp::socket::shutdown_send, ec); // avoid RST
            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) {
                if (ecode != boost::asio::error::operation_aborted) {
                    LogPrint(eLogError, "I2PTunnel: Read error: ", ecode.message());
                    Terminate();
                }
            } else
                WriteToStream(m_Buffer, bytes_transferred);
        }

        void I2PTunnelConnection::WriteToStream(const uint8_t *buf, size_t len) {
            if (m_Stream) {
                auto s = shared_from_this();
                m_Stream->AsyncSend(buf, len,
                                    [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 remaining 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) {
                if (ecode != boost::asio::error::operation_aborted) {
                    LogPrint(eLogError, "I2PTunnel: Stream read error: ", ecode.message());
                    if (bytes_transferred > 0)
                        Write(m_StreamBuffer, bytes_transferred); // postpone termination
                    else if (ecode == boost::asio::error::timed_out && m_Stream && m_Stream->IsOpen())
                        StreamReceive();
                    else
                        Terminate();
                } 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";
                    if (sizeof(m_StreamBuffer) >= dest.size()) {
                        memcpy(m_StreamBuffer, dest.c_str(), dest.size());
                    }
                    HandleStreamReceive(boost::system::error_code(), dest.size());
                }
                Receive();
            }
        }

        void I2PClientTunnelConnectionHTTP::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 (!m_ConnectionSent && !line.compare(0, 10, "Connection")) {
                                /* close connection, if not Connection: (U|u)pgrade (for websocket) */
                                auto x = line.find("pgrade");
                                if (x != std::string::npos && std::tolower(line[x - 1]) == 'u')
                                    m_OutHeader << line << "\r\n";
                                else
                                    m_OutHeader << "Connection: close\r\n";

                                m_ConnectionSent = true;
                            } else if (!m_ProxyConnectionSent && !line.compare(0, 16, "Proxy-Connection")) {
                                m_OutHeader << "Proxy-Connection: close\r\n";
                                m_ProxyConnectionSent = true;
                            } else
                                m_OutHeader << line << "\n";
                        }
                    } else
                        break;
                }

                if (endOfHeader) {
                    if (!m_ConnectionSent) m_OutHeader << "Connection: close\r\n";
                    if (!m_ProxyConnectionSent) m_OutHeader << "Proxy-Connection: close\r\n";
                    m_OutHeader << "\r\n"; // end of header
                    m_OutHeader << m_InHeader.str().substr(m_InHeader.tellg()); // data right after header
                    m_InHeader.str("");
                    m_HeaderSent = true;
                    I2PTunnelConnection::Write((uint8_t *) m_OutHeader.str().c_str(), m_OutHeader.str().length());
                } else if (m_OutHeader.tellp() < I2P_TUNNEL_HTTP_MAX_HEADER_SIZE)
                    StreamReceive(); // read more header
                else {
                    LogPrint(eLogError, "I2PTunnel: HTTP header exceeds max size ", I2P_TUNNEL_HTTP_MAX_HEADER_SIZE);
                    Terminate();
                }
            }
        }

        I2PServerTunnelConnectionHTTP::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) :
                I2PTunnelConnection(owner, stream, socket, target), m_Host(host),
                m_HeaderSent(false), m_ResponseHeaderSent(false), m_From(stream->GetRemoteIdentity()) {
        }

        void I2PServerTunnelConnectionHTTP::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, connection = false;
                while (!endOfHeader) {
                    std::getline(m_InHeader, line);
                    if (!m_InHeader.fail()) {
                        if (line == "\r") endOfHeader = true;
                        else {
                            // strip up some headers
                            static const std::vector <std::string> excluded // list of excluded headers
                                    {
                                            "Keep-Alive:", "X-I2P"
                                    };
                            bool matched = false;
                            for (const auto &it: excluded)
                                if (boost::iequals(line.substr(0, it.length()), it)) {
                                    matched = true;
                                    break;
                                }
                            if (matched) break;

                            // replace some headers
                            if (!m_Host.empty() && boost::iequals(line.substr(0, 5), "Host:"))
                                m_OutHeader << "Host: " << m_Host << "\r\n"; // override host
                            else if (boost::iequals(line.substr(0, 11), "Connection:")) {
                                auto x = line.find("pgrade");
                                if (x != std::string::npos && x &&
                                    std::tolower(line[x - 1]) != 'u') // upgrade or Upgrade
                                    m_OutHeader << line << "\n";
                                else
                                    m_OutHeader << "Connection: close\r\n";
                                connection = true;
                            } else // forward as is
                                m_OutHeader << line << "\n";
                        }
                    } else
                        break;
                }

                if (endOfHeader) {
                    // add Connection if not presented
                    if (!connection)
                        m_OutHeader << "Connection: close\r\n";
                    // 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";
                    }

                    m_OutHeader << "\r\n"; // end of header
                    m_OutHeader << m_InHeader.str().substr(m_InHeader.tellg()); // data right after header
                    m_InHeader.str("");
                    m_From = nullptr;
                    m_HeaderSent = true;
                    I2PTunnelConnection::Write((uint8_t *) m_OutHeader.str().c_str(), m_OutHeader.str().length());
                } else if (m_OutHeader.tellp() < I2P_TUNNEL_HTTP_MAX_HEADER_SIZE)
                    StreamReceive(); // read more header
                else {
                    LogPrint(eLogError, "I2PTunnel: HTTP header exceeds max size ", I2P_TUNNEL_HTTP_MAX_HEADER_SIZE);
                    Terminate();
                }
            }
        }

        void I2PServerTunnelConnectionHTTP::WriteToStream(const uint8_t *buf, size_t len) {
            if (m_ResponseHeaderSent)
                I2PTunnelConnection::WriteToStream(buf, len);
            else {
                m_InHeader.clear();
                if (m_InHeader.str().empty()) m_OutHeader.str(""); // start of response
                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 {
                            static const std::vector <std::string> excluded // list of excluded headers
                                    {
                                            "Server:", "Date:", "X-Runtime:", "X-Powered-By:", "Proxy"
                                    };
                            bool matched = false;
                            for (const auto &it: excluded)
                                if (!line.compare(0, it.length(), it)) {
                                    matched = true;
                                    break;
                                }
                            if (!matched)
                                m_OutHeader << line << "\n";
                        }
                    } else
                        break;
                }

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

        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) {
            m_OutPacket.str("");
            if (m_NeedsWebIrc) {
                m_NeedsWebIrc = false;
                m_OutPacket << "WEBIRC " << m_WebircPass << " cgiirc "
                            << context.GetAddressBook().ToAddress(m_From->GetIdentHash()) << " "
                            << GetSocket()->local_endpoint().address() << std::endl;
            }

            m_InPacket.clear();
            m_InPacket.write((const char *) buf, len);

            while (!m_InPacket.eof() && !m_InPacket.fail()) {
                std::string line;
                std::getline(m_InPacket, line);
                if (line.length() == 0 && m_InPacket.eof())
                    m_InPacket.str("");
                auto pos = line.find("USER");
                if (!pos) // start of line
                {
                    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 establish 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, std::shared_ptr<const Address> address,
                                   int destinationPort, std::shared_ptr <boost::asio::ip::tcp::socket> socket) :
                    I2PServiceHandler(parent), m_Address(address),
                    m_DestinationPort(destinationPort), m_Socket(socket) {};

            void Handle();

            void Terminate();

        private:
            void HandleStreamRequestComplete(std::shared_ptr <i2p::stream::Stream> stream);

            std::shared_ptr<const Address> m_Address;
            int m_DestinationPort;
            std::shared_ptr <boost::asio::ip::tcp::socket> m_Socket;
        };

        void I2PClientTunnelHandler::Handle() {
            GetOwner()->CreateStream(
                    std::bind(&I2PClientTunnelHandler::HandleStreamRequestComplete, shared_from_this(),
                              std::placeholders::_1),
                    m_Address, 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_DestinationPort(destinationPort), m_KeepAliveInterval(0) {
        }

        void I2PClientTunnel::Start() {
            TCPIPAcceptor::Start();
            GetAddress();
            if (m_KeepAliveInterval)
                ScheduleKeepAliveTimer();
        }

        void I2PClientTunnel::Stop() {
            TCPIPAcceptor::Stop();
            m_Address = nullptr;
            if (m_KeepAliveTimer) m_KeepAliveTimer->cancel();
        }

        void I2PClientTunnel::SetKeepAliveInterval(uint32_t keepAliveInterval) {
            m_KeepAliveInterval = keepAliveInterval;
            if (m_KeepAliveInterval)
                m_KeepAliveTimer.reset(new boost::asio::deadline_timer(GetLocalDestination()->GetService()));
        }

        /* HACK: maybe we should create a caching IdentHash provider in AddressBook */
        std::shared_ptr<const Address> I2PClientTunnel::GetAddress() {
            if (!m_Address) {
                m_Address = i2p::client::context.GetAddressBook().GetAddress(m_Destination);
                if (!m_Address)
                    LogPrint(eLogWarning, "I2PTunnel: Remote destination ", m_Destination, " not found");
            }
            return m_Address;
        }

        std::shared_ptr <I2PServiceHandler>
        I2PClientTunnel::CreateHandler(std::shared_ptr <boost::asio::ip::tcp::socket> socket) {
            auto address = GetAddress();
            if (address)
                return std::make_shared<I2PClientTunnelHandler>(this, address, m_DestinationPort, socket);
            else
                return nullptr;
        }

        void I2PClientTunnel::ScheduleKeepAliveTimer() {
            if (m_KeepAliveTimer) {
                m_KeepAliveTimer->expires_from_now(boost::posix_time::seconds(m_KeepAliveInterval));
                m_KeepAliveTimer->async_wait(std::bind(&I2PClientTunnel::HandleKeepAliveTimer,
                                                       this, std::placeholders::_1));
            }
        }

        void I2PClientTunnel::HandleKeepAliveTimer(const boost::system::error_code &ecode) {
            if (ecode != boost::asio::error::operation_aborted) {
                if (m_Address && m_Address->IsValid()) {
                    if (m_Address->IsIdentHash())
                        GetLocalDestination()->SendPing(m_Address->identHash);
                    else
                        GetLocalDestination()->SendPing(m_Address->blindedPublicKey);
                }
                ScheduleKeepAliveTimer();
            }
        }

        I2PServerTunnel::I2PServerTunnel(const std::string &name, const std::string &address,
                                         int port, std::shared_ptr <ClientDestination> localDestination, int inport,
                                         bool gzip) :
                I2PService(localDestination), m_IsUniqueLocal(true), 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() {
            if (m_PortDestination)
                m_PortDestination->ResetAcceptor();
            auto localDestination = GetLocalDestination();
            if (localDestination)
                localDestination->StopAcceptingStreams();

            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) {
                bool found = false;
                boost::asio::ip::tcp::endpoint ep;
                if (m_LocalAddress) {
                    boost::asio::ip::tcp::resolver::iterator end;
                    while (it != end) {
                        ep = *it;
                        if (!ep.address().is_unspecified()) {
                            if (ep.address().is_v4()) {
                                if (m_LocalAddress->is_v4()) found = true;
                            } else if (ep.address().is_v6()) {
                                if (i2p::util::net::IsYggdrasilAddress(ep.address())) {
                                    if (i2p::util::net::IsYggdrasilAddress(*m_LocalAddress))
                                        found = true;
                                } else if (m_LocalAddress->is_v6())
                                    found = true;
                            }
                        }
                        if (found) break;
                        it++;
                    }
                } else {
                    found = true;
                    ep = *it; // first available
                }
                if (!found) {
                    LogPrint(eLogError, "I2PTunnel: Unable to resolve to compatible address");
                    return;
                }

                auto addr = ep.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::SetLocalAddress(const std::string &localAddress) {
            boost::system::error_code ec;
            auto addr = boost::asio::ip::address::from_string(localAddress, ec);
            if (!ec)
                m_LocalAddress.reset(new boost::asio::ip::address(addr));
            else
                LogPrint(eLogError, "I2PTunnel: Can't set local address ", localAddress);
        }

        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;
                    }
                }
                // new connection
                auto conn = CreateI2PConnection(stream);
                AddHandler(conn);
                if (m_LocalAddress)
                    conn->Connect(*m_LocalAddress);
                else
                    conn->Connect(m_IsUniqueLocal);
            }
        }

        std::shared_ptr <I2PTunnelConnection>
        I2PServerTunnel::CreateI2PConnection(std::shared_ptr <i2p::stream::Stream> stream) {
            return std::make_shared<I2PTunnelConnection>(this, stream,
                                                         std::make_shared<boost::asio::ip::tcp::socket>(GetService()),
                                                         GetEndpoint());

        }

        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) {
        }

        std::shared_ptr <I2PTunnelConnection>
        I2PServerTunnelHTTP::CreateI2PConnection(std::shared_ptr <i2p::stream::Stream> stream) {
            return std::make_shared<I2PServerTunnelConnectionHTTP>(this, stream,
                                                                   std::make_shared<boost::asio::ip::tcp::socket>(
                                                                           GetService()), GetEndpoint(), m_Host);
        }

        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) {
        }

        std::shared_ptr <I2PTunnelConnection>
        I2PServerTunnelIRC::CreateI2PConnection(std::shared_ptr <i2p::stream::Stream> stream) {
            return std::make_shared<I2PTunnelConnectionIRC>(this, stream,
                                                            std::make_shared<boost::asio::ip::tcp::socket>(
                                                                    GetService()), GetEndpoint(), this->m_WebircPass);
        }

        void
        I2PUDPServerTunnel::HandleRecvFromI2P(const i2p::data::IdentityEx &from, uint16_t fromPort, uint16_t toPort,
                                              const uint8_t *buf, size_t len) {
            if (!m_LastSession || m_LastSession->Identity.GetLL()[0] != from.GetIdentHash().GetLL()[0] ||
                fromPort != m_LastSession->RemotePort) {
                std::lock_guard <std::mutex> lock(m_SessionsMutex);
                m_LastSession = ObtainUDPSession(from, toPort, fromPort);
            }
            m_LastSession->IPSocket.send_to(boost::asio::buffer(buf, len), m_RemoteEndpoint);
            m_LastSession->LastActivity = i2p::util::GetMillisecondsSinceEpoch();
        }

        void I2PUDPServerTunnel::HandleRecvFromI2PRaw(uint16_t, uint16_t, const uint8_t *buf, size_t len) {
            if (m_LastSession) {
                m_LastSession->IPSocket.send_to(boost::asio::buffer(buf, len), m_RemoteEndpoint);
                m_LastSession->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();
            auto itr = m_Sessions.begin();
            while (itr != m_Sessions.end()) {
                if (now - (*itr)->LastActivity >= delta)
                    itr = m_Sessions.erase(itr);
                else
                    ++itr;
            }
        }

        void I2PUDPClientTunnel::ExpireStale(const uint64_t delta) {
            std::lock_guard <std::mutex> lock(m_SessionsMutex);
            uint64_t now = i2p::util::GetMillisecondsSinceEpoch();
            std::vector <uint16_t> removePorts;
            for (const auto &s: m_Sessions) {
                if (now - s.second->second >= delta)
                    removePorts.push_back(s.first);
            }
            for (auto port: removePorts) {
                m_Sessions.erase(port);
            }
        }

        UDPSessionPtr I2PUDPServerTunnel::ObtainUDPSession(const i2p::data::IdentityEx &from, uint16_t localPort,
                                                           uint16_t remotePort) {
            auto ih = from.GetIdentHash();
            for (auto &s: m_Sessions) {
                if (s->Identity.GetLL()[0] == ih.GetLL()[0] && remotePort == s->RemotePort) {
                    /** found existing session */
                    LogPrint(eLogDebug, "UDPServer: Found session ", s->IPSocket.local_endpoint(), " ", ih.ToBase32());
                    return s;
                }
            }
            boost::asio::ip::address addr;
            /** create new udp session */
            if (m_IsUniqueLocal && m_LocalAddress.is_loopback()) {
                auto ident = from.GetIdentHash();
                addr = GetLoopbackAddressFor(ident);
            } else
                addr = m_LocalAddress;
            boost::asio::ip::udp::endpoint ep(addr, 0);
            m_Sessions.push_back(
                    std::make_shared<UDPSession>(ep, m_LocalDest, m_RemoteEndpoint, &ih, localPort, remotePort));
            auto &back = m_Sessions.back();
            return 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()),
                IPSocket(localDestination->GetService(), localEndpoint),
                SendEndpoint(endpoint),
                LastActivity(i2p::util::GetMillisecondsSinceEpoch()),
                LocalPort(ourPort),
                RemotePort(theirPort) {
            IPSocket.set_option(boost::asio::socket_base::receive_buffer_size(I2P_UDP_MAX_MTU));
            memcpy(Identity, to->data(), 32);
            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);
                auto ts = i2p::util::GetMillisecondsSinceEpoch();
                auto session = m_Destination->GetSession(Identity);
                if (ts > LastActivity + I2P_UDP_REPLIABLE_DATAGRAM_INTERVAL)
                    m_Destination->SendDatagram(session, m_Buffer, len, LocalPort, RemotePort);
                else
                    m_Destination->SendRawDatagram(session, m_Buffer, len, LocalPort, RemotePort);
                size_t numPackets = 0;
                while (numPackets < i2p::datagram::DATAGRAM_SEND_QUEUE_MAX_SIZE) {
                    boost::system::error_code ec;
                    size_t moreBytes = IPSocket.available(ec);
                    if (ec || !moreBytes) break;
                    len = IPSocket.receive_from(boost::asio::buffer(m_Buffer, I2P_UDP_MAX_MTU), FromEndpoint, 0, ec);
                    m_Destination->SendRawDatagram(session, m_Buffer, len, LocalPort, RemotePort);
                    numPackets++;
                }
                if (numPackets > 0)
                    LogPrint(eLogDebug, "UDPSession: Forward more ", numPackets, "packets B from ", FromEndpoint);
                m_Destination->FlushSendQueue(session);
                LastActivity = ts;
                Receive();
            } else
                LogPrint(eLogError, "UDPSession: ", ecode.message());
        }

        I2PUDPServerTunnel::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) :
                m_IsUniqueLocal(true), m_Name(name), m_LocalAddress(localAddress),
                m_RemoteEndpoint(forwardTo), m_LocalDest(localDestination), m_Gzip(gzip) {
        }

        I2PUDPServerTunnel::~I2PUDPServerTunnel() {
            Stop();
        }

        void I2PUDPServerTunnel::Start() {
            m_LocalDest->Start();

            auto dgram = m_LocalDest->CreateDatagramDestination(m_Gzip);
            dgram->SetReceiver(std::bind(&I2PUDPServerTunnel::HandleRecvFromI2P, this, std::placeholders::_1,
                                         std::placeholders::_2, std::placeholders::_3, std::placeholders::_4,
                                         std::placeholders::_5));
            dgram->SetRawReceiver(std::bind(&I2PUDPServerTunnel::HandleRecvFromI2PRaw, this, std::placeholders::_1,
                                            std::placeholders::_2, std::placeholders::_3, std::placeholders::_4));
        }

        void I2PUDPServerTunnel::Stop() {
            auto dgram = m_LocalDest->GetDatagramDestination();
            if (dgram) dgram->ResetReceiver();
        }

        std::vector <std::shared_ptr<DatagramSessionInfo>> I2PUDPServerTunnel::GetSessions() {
            std::vector <std::shared_ptr<DatagramSessionInfo>> sessions;
            std::lock_guard <std::mutex> lock(m_SessionsMutex);

            for (UDPSessionPtr s: m_Sessions) {
                if (!s->m_Destination) continue;
                auto info = s->m_Destination->GetInfoForRemote(s->Identity);
                if (!info) continue;

                auto sinfo = std::make_shared<DatagramSessionInfo>();
                sinfo->Name = m_Name;
                sinfo->LocalIdent = std::make_shared<i2p::data::IdentHash>(m_LocalDest->GetIdentHash().data());
                sinfo->RemoteIdent = std::make_shared<i2p::data::IdentHash>(s->Identity.data());
                sinfo->CurrentIBGW = info->IBGW;
                sinfo->CurrentOBEP = info->OBEP;
                sessions.push_back(sinfo);
            }
            return sessions;
        }

        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, bool gzip) :
                m_Name(name), m_RemoteDest(remoteDest), m_LocalDest(localDestination), m_LocalEndpoint(localEndpoint),
                m_RemoteIdent(nullptr), m_ResolveThread(nullptr), m_LocalSocket(nullptr), RemotePort(remotePort),
                m_LastPort(0), m_cancel_resolve(false), m_Gzip(gzip) {
        }

        I2PUDPClientTunnel::~I2PUDPClientTunnel() {
            Stop();
        }

        void I2PUDPClientTunnel::Start() {
            // Reset flag in case of tunnel reload
            if (m_cancel_resolve) m_cancel_resolve = false;

            m_LocalSocket.reset(new boost::asio::ip::udp::socket(m_LocalDest->GetService(), m_LocalEndpoint));
            m_LocalSocket->set_option(boost::asio::socket_base::receive_buffer_size(I2P_UDP_MAX_MTU));
            m_LocalSocket->set_option(boost::asio::socket_base::reuse_address(true));

            auto dgram = m_LocalDest->CreateDatagramDestination(m_Gzip);
            dgram->SetReceiver(std::bind(&I2PUDPClientTunnel::HandleRecvFromI2P, this,
                                         std::placeholders::_1, std::placeholders::_2,
                                         std::placeholders::_3, std::placeholders::_4,
                                         std::placeholders::_5));
            dgram->SetRawReceiver(std::bind(&I2PUDPClientTunnel::HandleRecvFromI2PRaw, this,
                                            std::placeholders::_1, std::placeholders::_2, std::placeholders::_3,
                                            std::placeholders::_4));

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

        void I2PUDPClientTunnel::Stop() {
            auto dgram = m_LocalDest->GetDatagramDestination();
            if (dgram) dgram->ResetReceiver();
            m_cancel_resolve = true;

            m_Sessions.clear();

            if (m_LocalSocket && m_LocalSocket->is_open())
                m_LocalSocket->close();

            if (m_ResolveThread) {
                m_ResolveThread->join();
                delete m_ResolveThread;
                m_ResolveThread = nullptr;
            }
            if (m_RemoteIdent) {
                delete m_RemoteIdent;
                m_RemoteIdent = nullptr;
            }
        }

        void I2PUDPClientTunnel::RecvFromLocal() {
            m_LocalSocket->async_receive_from(boost::asio::buffer(m_RecvBuff, I2P_UDP_MAX_MTU),
                                              m_RecvEndpoint, std::bind(&I2PUDPClientTunnel::HandleRecvFromLocal, this,
                                                                        std::placeholders::_1, std::placeholders::_2));
        }

        void I2PUDPClientTunnel::HandleRecvFromLocal(const boost::system::error_code &ec, std::size_t transferred) {
            if (m_cancel_resolve) {
                LogPrint(eLogDebug, "UDP Client: Ignoring incomming data: stopping");
                return;
            }
            if (ec) {
                LogPrint(eLogError, "UDP Client: Reading from socket error: ", ec.message(),
                         ". Restarting listener...");
                RecvFromLocal(); // Restart listener and continue work
                return;
            }
            if (!m_RemoteIdent) {
                LogPrint(eLogWarning, "UDP Client: Remote endpoint not resolved yet");
                RecvFromLocal();
                return; // drop, remote not resolved
            }
            auto remotePort = m_RecvEndpoint.port();
            if (!m_LastPort || m_LastPort != remotePort) {
                auto itr = m_Sessions.find(remotePort);
                if (itr != m_Sessions.end())
                    m_LastSession = itr->second;
                else {
                    m_LastSession = std::make_shared<UDPConvo>(boost::asio::ip::udp::endpoint(m_RecvEndpoint), 0);
                    m_Sessions.emplace(remotePort, m_LastSession);
                }
                m_LastPort = remotePort;
            }
            // send off to remote i2p destination
            auto ts = i2p::util::GetMillisecondsSinceEpoch();
            LogPrint(eLogDebug, "UDP Client: Send ", transferred, " to ", m_RemoteIdent->ToBase32(), ":", RemotePort);
            auto session = m_LocalDest->GetDatagramDestination()->GetSession(*m_RemoteIdent);
            if (ts > m_LastSession->second + I2P_UDP_REPLIABLE_DATAGRAM_INTERVAL)
                m_LocalDest->GetDatagramDestination()->SendDatagram(session, m_RecvBuff, transferred, remotePort,
                                                                    RemotePort);
            else
                m_LocalDest->GetDatagramDestination()->SendRawDatagram(session, m_RecvBuff, transferred, remotePort,
                                                                       RemotePort);
            size_t numPackets = 0;
            while (numPackets < i2p::datagram::DATAGRAM_SEND_QUEUE_MAX_SIZE) {
                boost::system::error_code ec;
                size_t moreBytes = m_LocalSocket->available(ec);
                if (ec || !moreBytes) break;
                transferred = m_LocalSocket->receive_from(boost::asio::buffer(m_RecvBuff, I2P_UDP_MAX_MTU),
                                                          m_RecvEndpoint, 0, ec);
                remotePort = m_RecvEndpoint.port();
                // TODO: check remotePort
                m_LocalDest->GetDatagramDestination()->SendRawDatagram(session, m_RecvBuff, transferred, remotePort,
                                                                       RemotePort);
                numPackets++;
            }
            if (numPackets)
                LogPrint(eLogDebug, "UDP Client: Sent ", numPackets, " more packets to ", m_RemoteIdent->ToBase32());
            m_LocalDest->GetDatagramDestination()->FlushSendQueue(session);

            // mark convo as active
            if (m_LastSession)
                m_LastSession->second = ts;
            RecvFromLocal();
        }

        std::vector <std::shared_ptr<DatagramSessionInfo>> I2PUDPClientTunnel::GetSessions() {
            // TODO: implement
            std::vector <std::shared_ptr<DatagramSessionInfo>> infos;
            return infos;
        }

        void I2PUDPClientTunnel::TryResolving() {
            i2p::util::SetThreadName("UDP Resolver");
            LogPrint(eLogInfo, "UDP Tunnel: Trying to resolve ", m_RemoteDest);

            std::shared_ptr<const Address> addr;
            while (!(addr = context.GetAddressBook().GetAddress(m_RemoteDest)) && !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;
            }
            if (!addr || !addr->IsIdentHash()) {
                LogPrint(eLogError, "UDP Tunnel: ", m_RemoteDest, " not found");
                return;
            }
            m_RemoteIdent = new i2p::data::IdentHash;
            *m_RemoteIdent = addr->identHash;
            LogPrint(eLogInfo, "UDP Tunnel: Resolved ", m_RemoteDest, " to ", m_RemoteIdent->ToBase32());
        }

        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)
                HandleRecvFromI2PRaw(fromPort, toPort, buf, len);
            else
                LogPrint(eLogWarning, "UDP Client: Unwarranted traffic from ", from.GetIdentHash().ToBase32());
        }

        void
        I2PUDPClientTunnel::HandleRecvFromI2PRaw(uint16_t fromPort, uint16_t toPort, const uint8_t *buf, size_t len) {
            auto itr = m_Sessions.find(toPort);
            // found convo ?
            if (itr != m_Sessions.end()) {
                // found convo
                if (len > 0) {
                    LogPrint(eLogDebug, "UDP Client: Got ", len, "B from ",
                             m_RemoteIdent ? m_RemoteIdent->ToBase32() : "");
                    m_LocalSocket->send_to(boost::asio::buffer(buf, len), itr->second->first);
                    // mark convo as active
                    itr->second->second = i2p::util::GetMillisecondsSinceEpoch();
                }
            } else
                LogPrint(eLogWarning, "UDP Client: Not tracking udp session using port ", (int) toPort);
        }
    }
}