SAM.cpp

#include <string.h>
#include <stdio.h>
#ifdef _MSC_VER
#include <stdlib.h>
#endif
#include <boost/lexical_cast.hpp>
#include "util/base64.h"
#include "Identity.h"
#include "util/Log.h"
#include "Destination.h"
#include "ClientContext.h"
#include "SAM.h"

namespace i2p
{
namespace client
{
    SAMSocket::SAMSocket (SAMBridge& owner): 
        m_Owner (owner), m_Socket (m_Owner.GetService ()), m_Timer (m_Owner.GetService ()),
        m_BufferOffset (0), m_SocketType (eSAMSocketTypeUnknown), m_IsSilent (false), 
        m_Stream (nullptr), m_Session (nullptr)
    {
    }

    SAMSocket::~SAMSocket ()
    {
        Terminate ();
    }   

    void SAMSocket::CloseStream ()
    {
        if (m_Stream)
        {   
            m_Stream->Close ();
            m_Stream.reset ();
        }   
    }   
        
    void SAMSocket::Terminate ()
    {
        CloseStream ();
        
        switch (m_SocketType)
        {
            case eSAMSocketTypeSession:
                m_Owner.CloseSession (m_ID);
            break;
            case eSAMSocketTypeStream:
            {
                if (m_Session)
                    m_Session->sockets.remove (shared_from_this ());
                break;
            }
            case eSAMSocketTypeAcceptor:
            {
                if (m_Session)
                {
                    m_Session->sockets.remove (shared_from_this ());
                    m_Session->localDestination->StopAcceptingStreams ();
                }
                break;
            }
            default:
                ;
        }
        m_SocketType = eSAMSocketTypeTerminated;
        m_Socket.close ();
    }

    void SAMSocket::ReceiveHandshake ()
    {
        m_Socket.async_read_some (boost::asio::buffer(m_Buffer, SAM_SOCKET_BUFFER_SIZE),                
            std::bind(&SAMSocket::HandleHandshakeReceived, shared_from_this (), 
            std::placeholders::_1, std::placeholders::_2));
    }

    void SAMSocket::HandleHandshakeReceived (const boost::system::error_code& ecode, std::size_t bytes_transferred)
    {
        if (ecode)
        {
            LogPrint ("SAM handshake read error: ", ecode.message ());
            if (ecode != boost::asio::error::operation_aborted)
                Terminate ();
        }
        else
        {   
            m_Buffer[bytes_transferred] = 0;
            char * eol = (char *)memchr (m_Buffer, '\n', bytes_transferred);
            if (eol)
                *eol = 0;
            LogPrint ("SAM handshake ", m_Buffer);
            char * separator = strchr (m_Buffer, ' ');
            if (separator)
            {
                separator = strchr (separator + 1, ' ');    
                if (separator) 
                    *separator = 0;
            }

            if (!strcmp (m_Buffer, SAM_HANDSHAKE))
            {
                std::string version("3.0");
                // try to find MIN and MAX, 3.0 if not found
                if (separator)
                {
                    separator++;
                    std::map<std::string, std::string> params;
                    ExtractParams (separator, params);
                    auto it = params.find (SAM_PARAM_MAX);
                    // TODO: check MIN as well
                    if (it != params.end ())
                        version = it->second;
                }
                if (version[0] == '3') // we support v3 (3.0 and 3.1) only
                {
#ifdef _MSC_VER
                    size_t l = sprintf_s (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_HANDSHAKE_REPLY, version.c_str ());
#else       
                    size_t l = snprintf (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_HANDSHAKE_REPLY, version.c_str ());
#endif
                    boost::asio::async_write (m_Socket, boost::asio::buffer (m_Buffer, l), boost::asio::transfer_all (),
                        std::bind(&SAMSocket::HandleHandshakeReplySent, shared_from_this (), 
                        std::placeholders::_1, std::placeholders::_2));
                }   
                else
                    SendMessageReply (SAM_HANDSHAKE_I2P_ERROR, strlen (SAM_HANDSHAKE_I2P_ERROR), true);
            }
            else
            {
                LogPrint ("SAM handshake mismatch");
                Terminate ();
            }
        }
    }

    void SAMSocket::HandleHandshakeReplySent (const boost::system::error_code& ecode, std::size_t bytes_transferred)
    {
        if (ecode)
        {
            LogPrint ("SAM handshake reply send error: ", ecode.message ());
            if (ecode != boost::asio::error::operation_aborted)
                Terminate ();
        }
        else
        {
            m_Socket.async_read_some (boost::asio::buffer(m_Buffer, SAM_SOCKET_BUFFER_SIZE),                
                std::bind(&SAMSocket::HandleMessage, shared_from_this (), 
                std::placeholders::_1, std::placeholders::_2)); 
        }   
    }

    void SAMSocket::SendMessageReply (const char * msg, size_t len, bool close)
    {
        if (!m_IsSilent) 
            boost::asio::async_write (m_Socket, boost::asio::buffer (msg, len), boost::asio::transfer_all (),
                std::bind(&SAMSocket::HandleMessageReplySent, shared_from_this (), 
                std::placeholders::_1, std::placeholders::_2, close));
        else
        {
            if (close)
                Terminate ();
            else
                Receive (); 
        }       
    }

    void SAMSocket::HandleMessageReplySent (const boost::system::error_code& ecode, std::size_t bytes_transferred, bool close)
    {
        if (ecode)
        {
            LogPrint ("SAM reply send error: ", ecode.message ());
            if (ecode != boost::asio::error::operation_aborted)
                Terminate ();
        }
        else
        {
            if (close)
                Terminate ();
            else
                Receive (); 
        }   
    }

    void SAMSocket::HandleMessage (const boost::system::error_code& ecode, std::size_t bytes_transferred)
    {
        if (ecode)
        {
            LogPrint ("SAM read error: ", ecode.message ());
            if (ecode != boost::asio::error::operation_aborted)
                Terminate ();
        }
        else
        {
            bytes_transferred += m_BufferOffset;
            m_BufferOffset = 0;
            m_Buffer[bytes_transferred] = 0;
            char * eol = (char *)memchr (m_Buffer, '\n', bytes_transferred);
            if (eol)
            {
                *eol = 0;
                char * separator = strchr (m_Buffer, ' ');
                if (separator)
                {
                    separator = strchr (separator + 1, ' ');    
                    if (separator) 
                        *separator = 0;
                    else
                        separator = eol;

                    if (!strcmp (m_Buffer, SAM_SESSION_CREATE))
                        ProcessSessionCreate (separator + 1, bytes_transferred - (separator - m_Buffer) - 1);
                    else if (!strcmp (m_Buffer, SAM_STREAM_CONNECT))
                        ProcessStreamConnect (separator + 1, bytes_transferred - (separator - m_Buffer) - 1);
                    else if (!strcmp (m_Buffer, SAM_STREAM_ACCEPT))
                        ProcessStreamAccept (separator + 1, bytes_transferred - (separator - m_Buffer) - 1);
                    else if (!strcmp (m_Buffer, SAM_DEST_GENERATE))
                        ProcessDestGenerate ();
                    else if (!strcmp (m_Buffer, SAM_NAMING_LOOKUP))
                        ProcessNamingLookup (separator + 1, bytes_transferred - (separator - m_Buffer) - 1);
                    else if (!strcmp (m_Buffer, SAM_DATAGRAM_SEND))
                    {
                        size_t len = bytes_transferred - (separator - m_Buffer) - 1;
                        size_t processed = ProcessDatagramSend (separator + 1, len, eol + 1);
                        if (processed < len)
                        {
                            m_BufferOffset = len - processed;
                            if (processed > 0)
                                memmove (m_Buffer, separator + 1 + processed, m_BufferOffset);
                            else
                            {
                                // restore string back
                                *separator = ' ';
                                *eol = '\n';
                            }
                        }   
                        // since it's SAM v1 reply is not expected
                        Receive ();
                    }
                    else        
                    {   
                        LogPrint (eLogError, "SAM unexpected message ", m_Buffer);      
                        Terminate ();
                    }
                }
                else
                {
                    LogPrint (eLogError, "SAM malformed message ", m_Buffer);
                    Terminate ();
                }
            }
            else
            {   
                LogPrint (eLogWarning, "SAM incomplete message ", bytes_transferred);
                m_BufferOffset = bytes_transferred;
                // try to receive remaining message
                Receive ();
            }
        }
    }

    void SAMSocket::ProcessSessionCreate (char * buf, size_t len)
    {
        LogPrint ("SAM session create: ", buf);
        std::map<std::string, std::string> params;
        ExtractParams (buf, params);
        std::string& style = params[SAM_PARAM_STYLE]; 
        std::string& id = params[SAM_PARAM_ID];
        std::string& destination = params[SAM_PARAM_DESTINATION];
        m_ID = id; 
        if (m_Owner.FindSession (id))
        {
            // session exists
            SendMessageReply (SAM_SESSION_CREATE_DUPLICATED_ID, strlen(SAM_SESSION_CREATE_DUPLICATED_ID), true);
            return;
        }

        // create destination   
        m_Session = m_Owner.CreateSession (id, destination == SAM_VALUE_TRANSIENT ? "" : destination, &params); 
        if (m_Session)
        {
            m_SocketType = eSAMSocketTypeSession;
            if (style == SAM_VALUE_DATAGRAM)
            {
                auto dest = m_Session->localDestination->CreateDatagramDestination ();
                dest->SetReceiver (std::bind (&SAMSocket::HandleI2PDatagramReceive, shared_from_this (), 
                    std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, std::placeholders::_4, std::placeholders::_5));
            }

            if (m_Session->localDestination->IsReady ())
                SendSessionCreateReplyOk ();
            else
            {
                m_Timer.expires_from_now (boost::posix_time::seconds(SAM_SESSION_READINESS_CHECK_INTERVAL));
                m_Timer.async_wait (std::bind (&SAMSocket::HandleSessionReadinessCheckTimer,
                    shared_from_this (), std::placeholders::_1));   
            }
        }
        else
            SendMessageReply (SAM_SESSION_CREATE_DUPLICATED_DEST, strlen(SAM_SESSION_CREATE_DUPLICATED_DEST), true);
    }

    void SAMSocket::HandleSessionReadinessCheckTimer (const boost::system::error_code& ecode)
    {
        if (ecode != boost::asio::error::operation_aborted)
        {
            if (m_Session->localDestination->IsReady ())
                SendSessionCreateReplyOk ();
            else
            {
                m_Timer.expires_from_now (boost::posix_time::seconds(SAM_SESSION_READINESS_CHECK_INTERVAL));
                m_Timer.async_wait (std::bind (&SAMSocket::HandleSessionReadinessCheckTimer,
                    shared_from_this (), std::placeholders::_1));
            }   
        }
    }

    void SAMSocket::SendSessionCreateReplyOk ()
    {
        uint8_t buf[1024];
        char priv[1024];
        size_t l = m_Session->localDestination->GetPrivateKeys ().ToBuffer (buf, 1024);
        size_t l1 = i2p::util::ByteStreamToBase64 (buf, l, priv, 1024);
        priv[l1] = 0;
#ifdef _MSC_VER
        size_t l2 = sprintf_s (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_SESSION_CREATE_REPLY_OK, priv);
#else       
        size_t l2 = snprintf (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_SESSION_CREATE_REPLY_OK, priv);
#endif
        SendMessageReply (m_Buffer, l2, false);
    }

    void SAMSocket::ProcessStreamConnect (char * buf, size_t len)
    {
        LogPrint (eLogDebug, "SAM stream connect: ", buf);
        std::map<std::string, std::string> params;
        ExtractParams (buf, params);
        std::string& id = params[SAM_PARAM_ID];
        std::string& destination = params[SAM_PARAM_DESTINATION];
        std::string& silent = params[SAM_PARAM_SILENT];
        if (silent == SAM_VALUE_TRUE) m_IsSilent = true;    
        m_ID = id;
        m_Session = m_Owner.FindSession (id);
        if (m_Session)
        {
            i2p::data::IdentityEx dest;
            size_t len = dest.FromBase64(destination);
            if (len > 0)
            {
                context.GetAddressBook().InsertAddress(dest);
                auto leaseSet = m_Session->localDestination->FindLeaseSet(dest.GetIdentHash());
                if (leaseSet)
                    Connect(leaseSet);
                else
                {
                    m_Session->localDestination->RequestDestination(dest.GetIdentHash(),
                        std::bind(&SAMSocket::HandleConnectLeaseSetRequestComplete,
                        shared_from_this(), std::placeholders::_1));
                }
            }
            else
                SendMessageReply(SAM_SESSION_STATUS_INVALID_KEY, strlen(SAM_SESSION_STATUS_INVALID_KEY), true);
        }
        else
            SendMessageReply (SAM_STREAM_STATUS_INVALID_ID, strlen(SAM_STREAM_STATUS_INVALID_ID), true);        
    }

    void SAMSocket::Connect (std::shared_ptr<const i2p::data::LeaseSet> remote)
    {
        m_SocketType = eSAMSocketTypeStream;
        m_Session->sockets.push_back (shared_from_this ());
        m_Stream = m_Session->localDestination->CreateStream (remote);
        m_Stream->Send ((uint8_t *)m_Buffer, 0); // connect
        I2PReceive ();          
        SendMessageReply (SAM_STREAM_STATUS_OK, strlen(SAM_STREAM_STATUS_OK), false);
    }

    void SAMSocket::HandleConnectLeaseSetRequestComplete (std::shared_ptr<i2p::data::LeaseSet> leaseSet)
    {
        if (leaseSet)
            Connect (leaseSet);
        else
        {
            LogPrint ("SAM destination to connect not found");
            SendMessageReply (SAM_STREAM_STATUS_CANT_REACH_PEER, strlen(SAM_STREAM_STATUS_CANT_REACH_PEER), true);
        }
    }

    void SAMSocket::ProcessStreamAccept (char * buf, size_t len)
    {
        LogPrint (eLogDebug, "SAM stream accept: ", buf);
        std::map<std::string, std::string> params;
        ExtractParams (buf, params);
        std::string& id = params[SAM_PARAM_ID];
        std::string& silent = params[SAM_PARAM_SILENT];
        if (silent == SAM_VALUE_TRUE) m_IsSilent = true;    
        m_ID = id;
        m_Session = m_Owner.FindSession (id);
        if (m_Session)
        {
            if (!m_Session->localDestination->IsAcceptingStreams ())
            {
                m_SocketType = eSAMSocketTypeAcceptor;
                m_Session->sockets.push_back (shared_from_this ());
                m_Session->localDestination->AcceptStreams (std::bind (&SAMSocket::HandleI2PAccept, shared_from_this (), std::placeholders::_1));
                SendMessageReply (SAM_STREAM_STATUS_OK, strlen(SAM_STREAM_STATUS_OK), false);
            }
            else
                SendMessageReply (SAM_STREAM_STATUS_I2P_ERROR, strlen(SAM_STREAM_STATUS_I2P_ERROR), true);
        }   
        else
            SendMessageReply (SAM_STREAM_STATUS_INVALID_ID, strlen(SAM_STREAM_STATUS_INVALID_ID), true);
    }

    size_t SAMSocket::ProcessDatagramSend (char * buf, size_t len, const char * data)
    {
        LogPrint (eLogDebug, "SAM datagram send: ", buf, " ", len);
        std::map<std::string, std::string> params;
        ExtractParams (buf, params);
        size_t size = boost::lexical_cast<int>(params[SAM_PARAM_SIZE]), offset = data - buf;
        if (offset + size <= len)
        {   
            if (m_Session)
            {   
                auto d = m_Session->localDestination->GetDatagramDestination ();
                if (d)
                {
                    i2p::data::IdentityEx dest;
                    dest.FromBase64 (params[SAM_PARAM_DESTINATION]);
                    d->SendDatagramTo ((const uint8_t *)data, size, dest.GetIdentHash ());
                }
                else
                    LogPrint (eLogError, "SAM missing datagram destination");
            }
            else
                LogPrint (eLogError, "SAM session is not created from DATAGRAM SEND");
        }   
        else
        {
            LogPrint (eLogWarning, "SAM sent datagram size ", size, " exceeds buffer ", len - offset);
            return 0; // try to receive more
        }   
        return offset + size;
    }   
        
    void SAMSocket::ProcessDestGenerate ()
    {
        LogPrint (eLogDebug, "SAM dest generate");
        auto keys = i2p::data::PrivateKeys::CreateRandomKeys ();
#ifdef _MSC_VER
        size_t len = sprintf_s (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_DEST_REPLY, 
            keys.GetPublic ().ToBase64 ().c_str (), keys.ToBase64 ().c_str ()); 
#else                                   
        size_t len = snprintf (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_DEST_REPLY, 
            keys.GetPublic ().ToBase64 ().c_str (), keys.ToBase64 ().c_str ());
#endif
        SendMessageReply (m_Buffer, len, false);
    }

    void SAMSocket::ProcessNamingLookup (char * buf, size_t len)
    {
        LogPrint (eLogDebug, "SAM naming lookup: ", buf);
        std::map<std::string, std::string> params;
        ExtractParams (buf, params);
        std::string& name = params[SAM_PARAM_NAME];
        i2p::data::IdentityEx identity;
        i2p::data::IdentHash ident;
        if (name == "ME")
            SendNamingLookupReply (m_Session->localDestination->GetIdentity ());
        else if (context.GetAddressBook ().GetAddress (name, identity))
            SendNamingLookupReply (identity);
        else if (m_Session && m_Session->localDestination &&
            context.GetAddressBook ().GetIdentHash (name, ident))
        {
            auto leaseSet = m_Session->localDestination->FindLeaseSet (ident);
            if (leaseSet)
                SendNamingLookupReply (leaseSet->GetIdentity ());
            else
                m_Session->localDestination->RequestDestination (ident, 
                    std::bind (&SAMSocket::HandleNamingLookupLeaseSetRequestComplete,
                    shared_from_this (), std::placeholders::_1, ident));    
        }   
        else 
        {
            LogPrint ("SAM naming failed. Unknown address ", name);
#ifdef _MSC_VER
            size_t len = sprintf_s (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_NAMING_REPLY_INVALID_KEY, name.c_str());
#else               
            size_t len = snprintf (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_NAMING_REPLY_INVALID_KEY, name.c_str());
#endif
            SendMessageReply (m_Buffer, len, false);
        }
    }   

    void  SAMSocket::HandleNamingLookupLeaseSetRequestComplete (std::shared_ptr<i2p::data::LeaseSet> leaseSet, i2p::data::IdentHash ident)
    {
        if (leaseSet)
        {   
            context.GetAddressBook ().InsertAddress (leaseSet->GetIdentity ());
            SendNamingLookupReply (leaseSet->GetIdentity ());
        }   
        else
        {
            LogPrint (eLogInfo, "SAM naming lookup failed. LeaseSet for ", ident.ToBase32 (), " not found");
#ifdef _MSC_VER
            size_t len = sprintf_s (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_NAMING_REPLY_INVALID_KEY, 
                context.GetAddressBook ().ToAddress (ident).c_str());
#else               
            size_t len = snprintf (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_NAMING_REPLY_INVALID_KEY,
                context.GetAddressBook ().ToAddress (ident).c_str());
#endif
            SendMessageReply (m_Buffer, len, false);
        }
    }   
        
    void SAMSocket::SendNamingLookupReply (const i2p::data::IdentityEx& identity)
    {
        auto base64 = identity.ToBase64 ();
#ifdef _MSC_VER
        size_t l = sprintf_s (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_NAMING_REPLY, base64.c_str ());     
#else           
        size_t l = snprintf (m_Buffer, SAM_SOCKET_BUFFER_SIZE, SAM_NAMING_REPLY, base64.c_str ());
#endif
        SendMessageReply (m_Buffer, l, false);
    }

    void SAMSocket::ExtractParams (char * buf, std::map<std::string, std::string>& params)
    {
        char * separator;   
        do
        {
            separator = strchr (buf, ' ');
            if (separator) *separator = 0;
            char * value = strchr (buf, '=');
            if (value)
            {
                *value = 0;
                value++;
                params[buf] = value;
            }   
            buf = separator + 1;
        }
        while (separator);
    }   

    void SAMSocket::Receive ()
    {
        if (m_BufferOffset >= SAM_SOCKET_BUFFER_SIZE)
        {
            LogPrint (eLogError, "Buffer is full. Terminate");
            Terminate ();
            return;
        }
        m_Socket.async_read_some (boost::asio::buffer(m_Buffer + m_BufferOffset, SAM_SOCKET_BUFFER_SIZE - m_BufferOffset),                
            std::bind((m_SocketType == eSAMSocketTypeStream) ? &SAMSocket::HandleReceived : &SAMSocket::HandleMessage,
            shared_from_this (), std::placeholders::_1, std::placeholders::_2));
    }

    void SAMSocket::HandleReceived (const boost::system::error_code& ecode, std::size_t bytes_transferred)
    {
        if (ecode)
        {
            LogPrint ("SAM read error: ", ecode.message ());
            if (ecode != boost::asio::error::operation_aborted)
                Terminate ();
        }
        else
        {
            if (m_Stream)
            {   
                auto s = shared_from_this ();
                m_Stream->AsyncSend ((uint8_t *)m_Buffer, bytes_transferred,
                    [s](const boost::system::error_code& ecode)
                    {
                        if (!ecode)
                            s->Receive ();
                        else
                            s->Terminate ();
                    });
            }   
        }
    }

    void SAMSocket::I2PReceive ()
    {
        if (m_Stream)
            m_Stream->AsyncReceive (boost::asio::buffer (m_StreamBuffer, SAM_SOCKET_BUFFER_SIZE),
                std::bind (&SAMSocket::HandleI2PReceive, shared_from_this (),
                    std::placeholders::_1, std::placeholders::_2),
                SAM_SOCKET_CONNECTION_MAX_IDLE);
    }   

    void SAMSocket::HandleI2PReceive (const boost::system::error_code& ecode, std::size_t bytes_transferred)
    {
        if (ecode)
        {
            LogPrint ("SAM stream read error: ", ecode.message ());
            if (ecode != boost::asio::error::operation_aborted)
                Terminate ();
        }
        else
        {
            boost::asio::async_write (m_Socket, boost::asio::buffer (m_StreamBuffer, bytes_transferred),
                std::bind (&SAMSocket::HandleWriteI2PData, shared_from_this (), std::placeholders::_1));
        }
    }

    void SAMSocket::HandleWriteI2PData (const boost::system::error_code& ecode)
    {
        if (ecode)
        {
            LogPrint ("SAM socket write error: ", ecode.message ());
            if (ecode != boost::asio::error::operation_aborted)
                Terminate ();
        }
        else
            I2PReceive ();
    }

    void SAMSocket::HandleI2PAccept (std::shared_ptr<i2p::stream::Stream> stream)
    {
        if (stream)
        {
            LogPrint ("SAM incoming I2P connection for session ", m_ID);
            m_Stream = stream;
            context.GetAddressBook ().InsertAddress (stream->GetRemoteIdentity ());
            auto session = m_Owner.FindSession (m_ID);
            if (session)    
                session->localDestination->StopAcceptingStreams (); 
            m_SocketType = eSAMSocketTypeStream;
            if (!m_IsSilent)
            {
                // send remote peer address
                uint8_t ident[1024];
                size_t l = stream->GetRemoteIdentity ().ToBuffer (ident, 1024);
                size_t l1 = i2p::util::ByteStreamToBase64 (ident, l, (char *)m_StreamBuffer, SAM_SOCKET_BUFFER_SIZE);
                m_StreamBuffer[l1] = '\n';
                HandleI2PReceive (boost::system::error_code (), l1 +1); // we send identity like it has been received from stream
            }   
            else
                I2PReceive ();
        }
        else
            LogPrint (eLogInfo, "SAM I2P acceptor has been reset");
    }   

    void SAMSocket::HandleI2PDatagramReceive (const i2p::data::IdentityEx& from, uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len)
    {
        LogPrint (eLogDebug, "SAM datagram received ", len);
        auto base64 = from.ToBase64 ();
#ifdef _MSC_VER
        size_t l = sprintf_s ((char *)m_StreamBuffer, SAM_SOCKET_BUFFER_SIZE, SAM_DATAGRAM_RECEIVED, base64.c_str (), len);     
#else           
        size_t l = snprintf ((char *)m_StreamBuffer, SAM_SOCKET_BUFFER_SIZE, SAM_DATAGRAM_RECEIVED, base64.c_str (), len);  
#endif
        if (len < SAM_SOCKET_BUFFER_SIZE - l)   
        {   
            memcpy (m_StreamBuffer + l, buf, len);
            boost::asio::async_write (m_Socket, boost::asio::buffer (m_StreamBuffer, len + l),
                std::bind (&SAMSocket::HandleWriteI2PData, shared_from_this (), std::placeholders::_1));
        }
        else
            LogPrint (eLogWarning, "SAM received datagram size ", len," exceeds buffer");
    }

    SAMSession::SAMSession (std::shared_ptr<ClientDestination> dest):
        localDestination (dest)
    {
    }
        
    SAMSession::~SAMSession ()
    {
        for (auto it: sockets)
            it->SetSocketType (eSAMSocketTypeTerminated);
        i2p::client::context.DeleteLocalDestination (localDestination);
    }

    void SAMSession::CloseStreams ()
    {
        for (auto it: sockets)
        {   
            it->CloseStream ();
            it->SetSocketType (eSAMSocketTypeTerminated);
        }   
        sockets.clear ();
    }

    SAMBridge::SAMBridge(const std::string& address, int port)
        : m_IsRunning (false), m_Thread (nullptr),
          m_Acceptor(m_Service, boost::asio::ip::tcp::endpoint(
            boost::asio::ip::address::from_string(address), port)
          ),
          m_DatagramEndpoint(boost::asio::ip::address::from_string(address), port - 1),
          m_DatagramSocket(m_Service, m_DatagramEndpoint)
    {
    }

    SAMBridge::~SAMBridge ()
    {
        if (m_IsRunning)
            Stop ();
    }   

    void SAMBridge::Start ()
    {
        Accept ();
        ReceiveDatagram ();
        m_IsRunning = true;
        m_Thread = new std::thread (std::bind (&SAMBridge::Run, this));
    }

    void SAMBridge::Stop ()
    {
        m_IsRunning = false;
        m_Acceptor.cancel ();
        for (auto it: m_Sessions)
            delete it.second;
        m_Sessions.clear ();
        m_Service.stop ();
        if (m_Thread)
        {   
            m_Thread->join (); 
            delete m_Thread;
            m_Thread = nullptr;
        }   
    }

    void SAMBridge::Run () 
    { 
        while (m_IsRunning)
        {
            try
            {   
                m_Service.run ();
            }
            catch (std::exception& ex)
            {
                LogPrint ("SAM: ", ex.what ());
            }   
        }   
    }

    void SAMBridge::Accept ()
    {
        auto newSocket = std::make_shared<SAMSocket> (*this);
        m_Acceptor.async_accept (newSocket->GetSocket (), std::bind (&SAMBridge::HandleAccept, this,
            std::placeholders::_1, newSocket));
    }

    void SAMBridge::HandleAccept(const boost::system::error_code& ecode, std::shared_ptr<SAMSocket> socket)
    {
        if (!ecode)
        {
            boost::system::error_code ec;
            auto ep = socket->GetSocket ().remote_endpoint (ec);
            if (!ec)
            {   
                LogPrint ("New SAM connection from ", ep);
                socket->ReceiveHandshake ();
            }
            else
                LogPrint (eLogError, "SAM connection from error ", ec.message ());
        }
        else
            LogPrint ("SAM accept error: ",  ecode.message ());

        if (ecode != boost::asio::error::operation_aborted)
            Accept ();
    }

    SAMSession * SAMBridge::CreateSession (const std::string& id, const std::string& destination, 
        const std::map<std::string, std::string> * params)
    {
        std::shared_ptr<ClientDestination> localDestination = nullptr; 
        if (destination != "")
        {
            i2p::data::PrivateKeys keys;
            keys.FromBase64 (destination);
            localDestination = i2p::client::context.CreateNewLocalDestination (keys, true, params);
        }
        else // transient
        {
            // extract signature type
            i2p::data::SigningKeyType signatureType = i2p::data::SIGNING_KEY_TYPE_DSA_SHA1;
            if (params)
            {
                auto it = params->find (SAM_PARAM_SIGNATURE_TYPE);
                if (it != params->end ())
                    // TODO: extract string values  
                    signatureType = boost::lexical_cast<int> (it->second);
            }
            localDestination = i2p::client::context.CreateNewLocalDestination (true, signatureType, params); 
        }
        if (localDestination)
        {
            std::unique_lock<std::mutex> l(m_SessionsMutex);
            auto ret = m_Sessions.insert (std::pair<std::string, SAMSession *>(id, new SAMSession (localDestination)));
            if (!ret.second)
                LogPrint ("Session ", id, " already exists");
            return ret.first->second;
        }
        return nullptr;
    }

    void SAMBridge::CloseSession (const std::string& id)
    {
        std::unique_lock<std::mutex> l(m_SessionsMutex);
        auto it = m_Sessions.find (id);
        if (it != m_Sessions.end ())
        {
            auto session = it->second;
            session->localDestination->StopAcceptingStreams ();
            session->CloseStreams ();
            m_Sessions.erase (it);
            delete session;
        }
    }

    SAMSession * SAMBridge::FindSession (const std::string& id) const
    {
        std::unique_lock<std::mutex> l(m_SessionsMutex);
        auto it = m_Sessions.find (id);
        if (it != m_Sessions.end ())
            return it->second;
        return nullptr;
    }

    void SAMBridge::ReceiveDatagram ()
    {
        m_DatagramSocket.async_receive_from (
            boost::asio::buffer (m_DatagramReceiveBuffer, i2p::datagram::MAX_DATAGRAM_SIZE), 
            m_SenderEndpoint,
            std::bind (&SAMBridge::HandleReceivedDatagram, this, std::placeholders::_1, std::placeholders::_2)); 
    }

    void SAMBridge::HandleReceivedDatagram (const boost::system::error_code& ecode, std::size_t bytes_transferred)
    {
        if (!ecode)
        {
            m_DatagramReceiveBuffer[bytes_transferred] = 0;
            char * eol = strchr ((char *)m_DatagramReceiveBuffer, '\n');
            *eol = 0; eol++;
            size_t payloadLen = bytes_transferred - ((uint8_t *)eol - m_DatagramReceiveBuffer); 
            LogPrint ("SAM datagram received ", m_DatagramReceiveBuffer," size=", payloadLen);
            char * sessionID = strchr ((char *)m_DatagramReceiveBuffer, ' ');
            if (sessionID)
            {
                sessionID++;
                char * destination = strchr (sessionID, ' ');
                if (destination)
                {
                    *destination = 0; destination++;
                    auto session = FindSession (sessionID);
                    if (session)
                    {   
                        i2p::data::IdentityEx dest;
                        dest.FromBase64 (destination);
                        session->localDestination->GetDatagramDestination ()->
                            SendDatagramTo ((uint8_t *)eol, payloadLen, dest.GetIdentHash ());
                    }   
                    else
                        LogPrint ("Session ", sessionID, " not found");
                }
                else
                    LogPrint ("Missing destination key");
            }
            else
                LogPrint ("Missing sessionID");
            ReceiveDatagram ();
        }
        else
            LogPrint ("SAM datagram receive error: ", ecode.message ());
    }
}
}