src/socket.cc: Source code reorganization

[barry/pauldeden.git] / src / socket.cc

///
/// \file       socket.cc
///             Class wrapper to encapsulate the Blackberry USB logical socket
///

/*
    Copyright (C) 2005-2008, Net Direct Inc. (http://www.netdirect.ca/)

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

    See the GNU General Public License in the COPYING file at the
    root directory of this project for more details.
*/

#include "socket.h"
#include "usbwrap.h"
#include "data.h"
#include "protocol.h"
#include "protostructs.h"
#include "endian.h"
#include "debug.h"
#include "packet.h"
#include <openssl/sha.h>
#include <sstream>

using namespace Usb;


namespace Barry {


//////////////////////////////////////////////////////////////////////////////
// SocketZero class

SocketZero::SocketZero( SocketRoutingQueue &queue,
                        int writeEndpoint,
                        uint8_t zeroSocketSequenceStart)
        : m_dev(0),
        m_queue(&queue),
        m_writeEp(writeEndpoint),
        m_readEp(0),
        m_zeroSocketSequence(zeroSocketSequenceStart),
        m_sequenceId(0),
        m_halfOpen(false),
        m_challengeSeed(0),
        m_remainingTries(0)
{
}

SocketZero::SocketZero( Device &dev,
                        int writeEndpoint, int readEndpoint,
                        uint8_t zeroSocketSequenceStart)
        : m_dev(&dev),
        m_queue(0),
        m_writeEp(writeEndpoint),
        m_readEp(readEndpoint),
        m_zeroSocketSequence(zeroSocketSequenceStart),
        m_sequenceId(0),
        m_halfOpen(false),
        m_challengeSeed(0),
        m_remainingTries(0)
{
}

SocketZero::~SocketZero()
{
        // nothing to close for socket zero
}


///////////////////////////////////////
// Socket Zero static calls

// appends fragment to whole... if whole is empty, simply copies, and
// sets command to DATA instead of FRAGMENTED.  Always updates the
// packet size of whole, to reflect the total size
void SocketZero::AppendFragment(Data &whole, const Data &fragment)
{
        if( whole.GetSize() == 0 ) {
                // empty, so just copy
                whole = fragment;
        }
        else {
                // has some data already, so just append
                int size = whole.GetSize();
                unsigned char *buf = whole.GetBuffer(size + fragment.GetSize());
                MAKE_PACKET(fpack, fragment);
                int fragsize = fragment.GetSize() - SB_FRAG_HEADER_SIZE;

                memcpy(buf+size, &fpack->u.db.u.fragment, fragsize);
                whole.ReleaseBuffer(size + fragsize);
        }

        // update whole's size and command type for future sanity
        Barry::Protocol::Packet *wpack = (Barry::Protocol::Packet *) whole.GetBuffer();
        wpack->size = htobs((uint16_t) whole.GetSize());
        wpack->command = SB_COMMAND_DB_DATA;
        // don't need to call ReleaseBuffer here, since we're not changing
        // the real data size, and ReleaseBuffer was called above during copy
}

// If offset is 0, starts fresh, taking the first fragment packet size chunk
// out of whole and creating a sendable packet in fragment.  Returns the
// next offset if there is still more data, or 0 if finished.
unsigned int SocketZero::MakeNextFragment(const Data &whole, Data &fragment, unsigned int offset)
{
        // sanity check
        if( whole.GetSize() < SB_FRAG_HEADER_SIZE ) {
                eout("Whole packet too short to fragment: " << whole.GetSize());
                throw Error("Socket: Whole packet too short to fragment");
        }

        // calculate size
        unsigned int todo = whole.GetSize() - SB_FRAG_HEADER_SIZE - offset;
        unsigned int nextOffset = 0;
        if( todo > (MAX_PACKET_SIZE - SB_FRAG_HEADER_SIZE) ) {
                todo = MAX_PACKET_SIZE - SB_FRAG_HEADER_SIZE;
                nextOffset = offset + todo;
        }

        // create fragment header
        unsigned char *buf = fragment.GetBuffer(SB_FRAG_HEADER_SIZE + todo);
        memcpy(buf, whole.GetData(), SB_FRAG_HEADER_SIZE);

        // copy over a fragment size of data
        memcpy(buf + SB_FRAG_HEADER_SIZE, whole.GetData() + SB_FRAG_HEADER_SIZE + offset, todo);

        // update fragment's size and command type
        Barry::Protocol::Packet *wpack = (Barry::Protocol::Packet *) buf;
        wpack->size = htobs((uint16_t) (todo + SB_FRAG_HEADER_SIZE));
        if( nextOffset )
                wpack->command = SB_COMMAND_DB_FRAGMENTED;
        else
                wpack->command = SB_COMMAND_DB_DATA;

        // adjust the new fragment size
        fragment.ReleaseBuffer(SB_FRAG_HEADER_SIZE + todo);

        // return next round
        return nextOffset;
}


///////////////////////////////////////
// SocketZero private API

//
// FIXME - not sure yet whether sequence ID's are per socket or not... if
// they are per socket, then this global sequence behaviour will not work,
// and we need to track m_sequenceId on a Socket level.
//
void SocketZero::CheckSequence(uint16_t socket, const Data &seq)
{
        MAKE_PACKET(spack, seq);
        if( (unsigned int) seq.GetSize() < SB_SEQUENCE_PACKET_SIZE ) {
                eout("Short sequence packet:\n" << seq);
                throw Error("Socket: invalid sequence packet");
        }

        // we'll cheat here... if the packet's sequence is 0, we'll
        // silently restart, otherwise, fail
        uint32_t sequenceId = btohl(spack->u.sequence.sequenceId);
        if( sequenceId == 0 ) {
                // silently restart (will advance below)
                m_sequenceId = 0;
        }
        else {
                if( sequenceId != m_sequenceId ) {
                        if( socket != 0 ) {
                                std::ostringstream oss;
                                oss << "Socket 0x" << std::hex << (unsigned int)socket
                                        << ": out of sequence. "
                                        << "(Global sequence: " << m_sequenceId
                                        << ". Packet sequence: " << sequenceId
                                        << ")";
                                eout(oss.str());
                                throw Error(oss.str());
                        }
                        else {
                                dout("Bad sequence on socket 0: expected: "
                                        << msequenceId
                                        << ". Packet sequence: " << sequenceId);
                        }
                }
        }

        // advance!
        m_sequenceId++;
}

void SocketZero::SendOpen(uint16_t socket, Data &receive)
{
        // build open command
        Barry::Protocol::Packet packet;
        packet.socket = 0;
        packet.size = htobs(SB_SOCKET_PACKET_HEADER_SIZE);
        packet.command = SB_COMMAND_OPEN_SOCKET;
        packet.u.socket.socket = htobs(socket);
        packet.u.socket.sequence = m_zeroSocketSequence;// overwritten by Send()

        Data send(&packet, SB_SOCKET_PACKET_HEADER_SIZE);
        try {
                RawSend(send);
                RawReceive(receive);
        } catch( Usb::Error & ) {
                eeout(send, receive);
                throw;
        }

        // check sequence ID
        Protocol::CheckSize(receive);
        if( IS_COMMAND(receive, SB_COMMAND_SEQUENCE_HANDSHAKE) ) {
                CheckSequence(0, receive);

                // still need our ACK
                RawReceive(receive);
        }

        // receive now holds the Open response
}

// SHA1 hashing logic based on Rick Scott's XmBlackBerry's send_password()
void SocketZero::SendPasswordHash(uint16_t socket, const char *password, Data &receive)
{
        unsigned char pwdigest[SHA_DIGEST_LENGTH];
        unsigned char prefixedhash[SHA_DIGEST_LENGTH + 4];

        // first, hash the password by itself
        SHA1((unsigned char *) password, strlen(password), pwdigest);

        // prefix the resulting hash with the provided seed
        uint32_t seed = htobl(m_challengeSeed);
        memcpy(&prefixedhash[0], &seed, sizeof(uint32_t));
        memcpy(&prefixedhash[4], pwdigest, SHA_DIGEST_LENGTH);

        // hash again
        SHA1((unsigned char *) prefixedhash, SHA_DIGEST_LENGTH + 4, pwdigest);


        size_t size = SB_SOCKET_PACKET_HEADER_SIZE + PASSWORD_CHALLENGE_SIZE;

        // build open command
        Barry::Protocol::Packet packet;
        packet.socket = 0;
        packet.size = htobs(size);
        packet.command = SB_COMMAND_PASSWORD;
        packet.u.socket.socket = htobs(socket);
        packet.u.socket.sequence = m_zeroSocketSequence;// overwritten by Send()
        packet.u.socket.u.password.remaining_tries = 0;
        packet.u.socket.u.password.unknown = 0;
        packet.u.socket.u.password.param = htobs(0x14); // FIXME - what does this mean?
        memcpy(packet.u.socket.u.password.u.hash, pwdigest,
                sizeof(packet.u.socket.u.password.u.hash));

        // blank password hashes as we don't need these anymore
        memset(pwdigest, 0, sizeof(pwdigest));
        memset(prefixedhash, 0, sizeof(prefixedhash));

        Data send(&packet, size);
        RawSend(send);
        RawReceive(receive);

        // blank password hash as we don't need this anymore either
        memset(packet.u.socket.u.password.u.hash, 0,
                sizeof(packet.u.socket.u.password.u.hash));
        send.Zap();

        // check sequence ID
        Protocol::CheckSize(receive);
        if( IS_COMMAND(receive, SB_COMMAND_SEQUENCE_HANDSHAKE) ) {
                CheckSequence(0, receive);

                // still need our ACK
                RawReceive(receive);
        }

        // receive now holds the Password response
}

void SocketZero::RawSend(Data &send, int timeout)
{
        Usb::Device *dev = m_queue ? m_queue->GetUsbDevice() : m_dev;

        // Special case: it seems that sending packets with a size that's an
        // exact multiple of 0x40 causes the device to get confused.
        //
        // To get around that, it is observed in the captures that the size
        // is sent in a special 3 byte packet before the real packet.
        // Check for this case here.
        //
        if( (send.GetSize() % 0x40) == 0 ) {
                Protocol::SizePacket packet;
                packet.size = htobs(send.GetSize());
                packet.buffer[2] = 0;           // zero the top byte
                Data sizeCommand(&packet, 3);

                dev->BulkWrite(m_writeEp, sizeCommand);
        }

        dev->BulkWrite(m_writeEp, send);
}

void SocketZero::RawReceive(Data &receive, int timeout)
{
        do {
                if( m_queue ) {
                        if( !m_queue->DefaultRead(receive, timeout) )
                                throw Timeout("SocketZero::RawReceive: queue DefaultRead returned false (likely a timeout)");
                }
                else {
                        m_dev->BulkRead(m_readEp, receive, timeout);
                }
                ddout("SocketZero::RawReceive: Endpoint " << m_readEp
                        << "\nReceived:\n" << receive);
        } while( SequencePacket(receive) );
}

//
// SequencePacket
//
/// Returns true if this is a sequence packet that should be ignored.
/// This function is used in SocketZero::RawReceive() in order
/// to determine whether to keep reading or not.  By default,
/// this function checks whether the packet is a sequence packet
/// or not, and returns true if so.  Also, if it is a sequence
/// packet, it checks the validity of the sequence number.
///
/// If sequence packets become important in the future, this
/// function could be changed to call a user-defined callback,
/// in order to handle these things out of band.
///
bool SocketZero::SequencePacket(const Data &data)
{
        if( data.GetSize() >= MIN_PACKET_SIZE ) {
                if( IS_COMMAND(data, SB_COMMAND_SEQUENCE_HANDSHAKE) ) {
                        CheckSequence(0, data);
                        return true;
                }
        }
        return false;   // not a sequence packet
}


///////////////////////////////////////
// SocketZero public API

void SocketZero::SetRoutingQueue(SocketRoutingQueue &queue)
{
        // replace the current queue pointer
        m_queue = &queue;
}

void SocketZero::UnlinkRoutingQueue()
{
        m_queue = 0;
}

void SocketZero::Send(Data &send, int timeout)
{
        // force the socket number to 0
        if( send.GetSize() >= SB_SOCKET_PACKET_HEADER_SIZE ) {
                MAKE_PACKETPTR_BUF(spack, send.GetBuffer());
                spack->socket = 0;
        }

        // This is a socket 0 packet, so force the send packet data's
        // socket 0 sequence number to something correct.
        if( send.GetSize() >= SB_SOCKET_PACKET_HEADER_SIZE ) {
                MAKE_PACKETPTR_BUF(spack, send.GetBuffer());
                spack->u.socket.sequence = m_zeroSocketSequence;
                m_zeroSocketSequence++;
        }

        RawSend(send, timeout);
}

void SocketZero::Send(Data &send, Data &receive, int timeout)
{
        Send(send, timeout);
        RawReceive(receive, timeout);
}

void SocketZero::Send(Barry::Packet &packet, int timeout)
{
        Send(packet.m_send, packet.m_receive, timeout);
}


//
// Open
//
/// Open a logical socket on the device.
///
/// Both the socket number and the flag are based on the response to the
/// SELECT_MODE command.  See Controller::SelectMode() for more info
/// on this.
///
/// The packet sequence is normal for most socket operations.
///
///     - Down: command packet with OPEN_SOCKET
///     - Up: optional sequence handshake packet
///     - Up: command response, which repeats the socket and flag data
///             as confirmation
///
/// \exception  Barry::Error
///             Thrown on protocol error.
///
/// \exception  Barry::BadPassword
///             Thrown on invalid password, or not enough retries left
///             on device.
///
SocketHandle SocketZero::Open(uint16_t socket, const char *password)
{
        // Things get a little funky here, as we may be left in an
        // intermediate state in the case of a failed password.
        // This function should support being called as many times
        // as needed to handle the password

        Data send, receive;
        ZeroPacket packet(send, receive);

        // save sequence for later close
        uint8_t closeFlag = GetZeroSocketSequence();

        if( !m_halfOpen ) {
                // starting fresh
                m_remainingTries = 0;

                SendOpen(socket, receive);

                // check for password challenge, or success
                if( packet.Command() == SB_COMMAND_PASSWORD_CHALLENGE ) {
                        m_halfOpen = true;
                        m_challengeSeed = packet.ChallengeSeed();
                        m_remainingTries = packet.RemainingTries();
                }

                // fall through to challenge code...
        }

        if( m_halfOpen ) {
                // half open, device is expecting a password hash... do we
                // have a password?
                if( !password ) {
                        throw BadPassword("No password specified.", m_remainingTries, false);
                }

                // only allow password attempts if there are 6 or more
                // tries remaining... we want to give the user at least
                // 5 chances on a Windows machine before the device
                // commits suicide.
                if( m_remainingTries < 6 ) {
                        throw BadPassword("Fewer than 6 password tries "
                                "remaining in device. Refusing to proceed, "
                                "to avoid device zapping itself.  Use a "
                                "Windows client, or re-cradle the device.",
                                m_remainingTries,
                                true);
                }

                // save sequence for later close (again after SendOpen())
                closeFlag = GetZeroSocketSequence();

                SendPasswordHash(socket, password, receive);

                if( packet.Command() == SB_COMMAND_PASSWORD_FAILED ) {
                        m_halfOpen = true;
                        m_challengeSeed = packet.ChallengeSeed();
                        m_remainingTries = packet.RemainingTries();
                        throw BadPassword("Password rejected by device.", m_remainingTries, false);
                }

                // if we get this far, we are no longer in half-open password
                // mode, so we can reset our flags
                m_halfOpen = false;

                // fall through to success check...
        }

        if( packet.Command() != SB_COMMAND_OPENED_SOCKET ||
            packet.SocketResponse() != socket ||
            packet.SocketSequence() != closeFlag )
        {
                eout("Packet:\n" << receive);
                throw Error("Socket: Bad OPENED packet in Open");
        }

        // success!  save the socket
        return SocketHandle(new Socket(*this, socket, closeFlag));
}

//
// Close
//
/// Closes a non-default socket (i.e. non-zero socket number)
///
/// The packet sequence is just like Open(), except the command is
/// CLOSE_SOCKET.
///
/// \exception  Barry::Error
///
void SocketZero::Close(Socket &socket)
{
        if( socket.GetSocket() == 0 )
                return;         // nothing to do

        // build close command
        Barry::Protocol::Packet packet;
        packet.socket = 0;
        packet.size = htobs(SB_SOCKET_PACKET_HEADER_SIZE);
        packet.command = SB_COMMAND_CLOSE_SOCKET;
        packet.u.socket.socket = htobs(socket.GetSocket());
        packet.u.socket.sequence = socket.GetCloseFlag();

        Data command(&packet, SB_SOCKET_PACKET_HEADER_SIZE);
        Data response;
        try {
                Send(command, response);
        }
        catch( Usb::Error & ) {
                // reset so this won't be called again
                socket.ForceClosed();

                eeout(command, response);
                throw;
        }

        // starting fresh, reset sequence ID
        Protocol::CheckSize(response);
        if( IS_COMMAND(response, SB_COMMAND_SEQUENCE_HANDSHAKE) ) {
                CheckSequence(0, response);

                // still need our ACK
                RawReceive(response);
        }

        Protocol::CheckSize(response, SB_SOCKET_PACKET_HEADER_SIZE);
        MAKE_PACKET(rpack, response);
        if( rpack->command != SB_COMMAND_CLOSED_SOCKET ||
            btohs(rpack->u.socket.socket) != socket.GetSocket() ||
            rpack->u.socket.sequence != socket.GetCloseFlag() )
        {
                // reset so this won't be called again
                socket.ForceClosed();

                eout("Packet:\n" << response);
                throw Error("Socket: Bad CLOSED packet in Close");
        }

//      // and finally, there always seems to be an extra read of
//      // an empty packet at the end... just throw it away
//      try {
//              RawReceive(response, 1);
//      }
//      catch( Usb::Timeout & ) {
//      }

        // reset socket and flag
        socket.ForceClosed();
}






//////////////////////////////////////////////////////////////////////////////
// Socket class

Socket::Socket( SocketZero &zero,
                uint16_t socket,
                uint8_t closeFlag)
        : m_zero(&zero)
        , m_socket(socket)
        , m_closeFlag(closeFlag)
        , m_registered(false)
{
}

Socket::~Socket()
{
        // trap exceptions in the destructor
        try {
                // a non-default socket has been opened, close it
                Close();
        }
        catch( std::runtime_error &re ) {
                // do nothing... log it?
                dout("Exception caught in ~Socket: " << re.what());
        }
}


////////////////////////////////////
// Socket protected API

void Socket::CheckSequence(const Data &seq)
{
        m_zero->CheckSequence(m_socket, seq);
}

void Socket::ForceClosed()
{
        m_socket = 0;
        m_closeFlag = 0;
}


////////////////////////////////////
// Socket public API

void Socket::Close()
{
        UnregisterInterest();
        m_zero->Close(*this);
}


//
// Send
//
/// Sends 'send' data to device, no receive.
///
/// \returns    void
///
/// \exception  Usb::Error on underlying bus errors.
///
void Socket::Send(Data &send, int timeout)
{
        // force the socket number to this socket
        if( send.GetSize() >= SB_PACKET_HEADER_SIZE ) {
                MAKE_PACKETPTR_BUF(spack, send.GetBuffer());
                spack->socket = htobs(m_socket);
        }
        m_zero->RawSend(send, timeout);
}

//
// Send
//
/// Sends 'send' data to device, and waits for response.
///
/// \returns    void
///
/// \exception  Usb::Error on underlying bus errors.
///
void Socket::Send(Data &send, Data &receive, int timeout)
{
        Send(send, timeout);
        Receive(receive, timeout);
}

void Socket::Send(Barry::Packet &packet, int timeout)
{
        Send(packet.m_send, packet.m_receive, timeout);
}

void Socket::Receive(Data &receive, int timeout)
{
        if( m_registered ) {
                if( m_zero->m_queue ) {
                        if( !m_zero->m_queue->SocketRead(m_socket, receive, timeout) )
                                throw Timeout("Socket::Receive: queue SocketRead returned false (likely a timeout)");
                }
                else {
                        throw std::logic_error("NULL queue pointer in a registered socket read.");
                }
        }
        else {
                m_zero->RawReceive(receive, timeout);
        }
}

// sends the send packet down to the device, fragmenting if
// necessary, and returns the response in receive, defragmenting
// if needed
// Blocks until response received or timed out in Usb::Device
void Socket::Packet(Data &send, Data &receive, int timeout)
{
/*
// FIXME - this might be a good idea someday, or perhaps provide a wrapper
// function that forces the socket number to the correct current value,
// but putting it here means a copy on every packet.

        // force socket to our socket
        Data send = sendorig;
        Barry::Protocol::Packet *sspack = (Barry::Protocol::Packet *)send.GetBuffer(2);
        sspack->socket = htobs(GetSocket());
*/

        MAKE_PACKET(spack, send);
        if( send.GetSize() < MIN_PACKET_SIZE ||
            (spack->command != SB_COMMAND_DB_DATA &&
             spack->command != SB_COMMAND_DB_DONE) )
        {
                // we don't do that around here
                throw std::logic_error("Socket: unknown send data in Packet()");
        }

        Data inFrag;
        receive.Zap();

        if( send.GetSize() <= MAX_PACKET_SIZE ) {
                // send non-fragmented
                Send(send, inFrag, timeout);
        }
        else {
                // send fragmented
                unsigned int offset = 0;
                Data outFrag;

                do {
                        offset = SocketZero::MakeNextFragment(send, outFrag, offset);
                        Send(outFrag, inFrag, timeout);

                        MAKE_PACKET(rpack, inFrag);
                        // only process sequence handshakes... once we
                        // get to the last fragment, we fall through to normal
                        // processing below
                        if( offset && inFrag.GetSize() > 0 ) {

                                Protocol::CheckSize(inFrag);

                                switch( rpack->command )
                                {
                                case SB_COMMAND_SEQUENCE_HANDSHAKE:
                                        CheckSequence(inFrag);
                                        break;

                                default: {
                                        std::ostringstream oss;
                                        oss << "Socket: unhandled packet in Packet() (send): 0x" << std::hex << (unsigned int)rpack->command;
                                        eout(oss.str());
                                        throw Error(oss.str());
                                        }
                                        break;
                                }
                        }


                } while( offset > 0 );
        }

        bool done = false, frag = false;
        int blankCount = 0;
        while( !done ) {
                MAKE_PACKET(rpack, inFrag);

                // check the packet's validity
                if( inFrag.GetSize() > 0 ) {
                        blankCount = 0;

                        Protocol::CheckSize(inFrag);

                        switch( rpack->command )
                        {
                        case SB_COMMAND_SEQUENCE_HANDSHAKE:
                                CheckSequence(inFrag);
                                break;

                        case SB_COMMAND_DB_DATA:
                                if( frag ) {
                                        SocketZero::AppendFragment(receive, inFrag);
                                }
                                else {
                                        receive = inFrag;
                                }
                                done = true;
                                break;

                        case SB_COMMAND_DB_FRAGMENTED:
                                SocketZero::AppendFragment(receive, inFrag);
                                frag = true;
                                break;

                        case SB_COMMAND_DB_DONE:
                                receive = inFrag;
                                done = true;
                                break;

                        default: {
                                std::ostringstream oss;
                                oss << "Socket: unhandled packet in Packet() (read): 0x" << std::hex << (unsigned int)rpack->command;
                                eout(oss.str());
                                throw Error(oss.str());
                                }
                                break;
                        }
                }
                else {
                        blankCount++;
                        //std::cerr << "Blank! " << blankCount << std::endl;
                        if( blankCount == 10 ) {
                                // only ask for more data on stalled sockets
                                // for so long
                                throw Error("Socket: 10 blank packets received");
                        }
                }

                if( !done ) {
                        // not done yet, ask for another read
                        Receive(inFrag);
                }
        }
}

void Socket::Packet(Barry::Packet &packet, int timeout)
{
        Packet(packet.m_send, packet.m_receive, timeout);
}

void Socket::NextRecord(Data &receive)
{
        Barry::Protocol::Packet packet;
        packet.socket = htobs(GetSocket());
        packet.size = htobs(7);
        packet.command = SB_COMMAND_DB_DONE;
        packet.u.db.tableCmd = 0;
        packet.u.db.u.command.operation = 0;

        Data command(&packet, 7);
        Packet(command, receive);
}

void Socket::RegisterInterest(SocketRoutingQueue::SocketDataHandler handler,
                                void *context)
{
        if( !m_zero->m_queue )
                throw std::logic_error("SocketRoutingQueue required in SocketZero in order to call Socket::RegisterInterest()");

        if( m_registered )
                throw std::logic_error("Socket already registered in Socket::RegisterInterest()!");

        m_zero->m_queue->RegisterInterest(m_socket, handler, context);
        m_registered = true;
}

void Socket::UnregisterInterest()
{
        if( m_registered ) {
                if( m_zero->m_queue )
                        m_zero->m_queue->UnregisterInterest(m_socket);
                m_registered = false;
        }
}


} // namespace Barry