CTCPSocket.cpp

/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2012 Bolton Software Ltd.
 * Copyright (C) 2002 Chris Schoeneman
 * 
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file COPYING that should have accompanied this file.
 * 
 * This package 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "CTCPSocket.h"
#include "CNetworkAddress.h"
#include "CSocketMultiplexer.h"
#include "TSocketMultiplexerMethodJob.h"
#include "XSocket.h"
#include "CLock.h"
#include "CLog.h"
#include "IEventQueue.h"
#include "IEventJob.h"
#include "CArch.h"
#include "XArch.h"
#include <cstring>
#include <cstdlib>
#include <memory>

//
// CTCPSocket
//

CTCPSocket::CTCPSocket() :
    m_mutex(),
    m_flushed(&m_mutex, true)
{
    try {
        m_socket = ARCH->newSocket(IArchNetwork::kINET, IArchNetwork::kSTREAM);
    }
    catch (XArchNetwork& e) {
        throw XSocketCreate(e.what());
    }

    init();
}

CTCPSocket::CTCPSocket(CArchSocket socket) :
    m_mutex(),
    m_socket(socket),
    m_flushed(&m_mutex, true)
{
    assert(m_socket != NULL);

    // socket starts in connected state
    init();
    onConnected();
    setJob(newJob());
}

CTCPSocket::~CTCPSocket()
{
    try {
        close();
    }
    catch (...) {
        // ignore
    }
}

void
CTCPSocket::bind(const CNetworkAddress& addr)
{
    try {
        ARCH->bindSocket(m_socket, addr.getAddress());
    }
    catch (XArchNetworkAddressInUse& e) {
        throw XSocketAddressInUse(e.what());
    }
    catch (XArchNetwork& e) {
        throw XSocketBind(e.what());
    }
}

void
CTCPSocket::close()
{
    // remove ourself from the multiplexer
    setJob(NULL);

    CLock lock(&m_mutex);

    // clear buffers and enter disconnected state
    if (m_connected) {
        sendEvent(getDisconnectedEvent());
    }
    onDisconnected();

    // close the socket
    if (m_socket != NULL) {
        CArchSocket socket = m_socket;
        m_socket = NULL;
        try {
            ARCH->closeSocket(socket);
        }
        catch (XArchNetwork& e) {
            // ignore, there's not much we can do
            LOG((CLOG_WARN "error closing socket: %s", e.what().c_str()));
        }
    }
}

void*
CTCPSocket::getEventTarget() const
{
    return const_cast<void*>(reinterpret_cast<const void*>(this));
}

UInt32
CTCPSocket::read(void* buffer, UInt32 n)
{
    // copy data directly from our input buffer
    CLock lock(&m_mutex);
    UInt32 size = m_inputBuffer.getSize();
    if (n > size) {
        n = size;
    }
    if (buffer != NULL && n != 0) {
        memcpy(buffer, m_inputBuffer.peek(n), n);
    }
    m_inputBuffer.pop(n);

    // if no more data and we cannot read or write then send disconnected
    if (n > 0 && m_inputBuffer.getSize() == 0 && !m_readable && !m_writable) {
        sendEvent(getDisconnectedEvent());
        m_connected = false;
    }

    return n;
}

void
CTCPSocket::write(const void* buffer, UInt32 n)
{
    bool wasEmpty;
    {
        CLock lock(&m_mutex);

        // must not have shutdown output
        if (!m_writable) {
            sendEvent(getOutputErrorEvent());
            return;
        }

        // ignore empty writes
        if (n == 0) {
            return;
        }

        // copy data to the output buffer
        wasEmpty = (m_outputBuffer.getSize() == 0);
        m_outputBuffer.write(buffer, n);

        // there's data to write
        m_flushed = false;
    }

    // make sure we're waiting to write
    if (wasEmpty) {
        setJob(newJob());
    }
}

void
CTCPSocket::flush()
{
    CLock lock(&m_mutex);
    while (m_flushed == false) {
        m_flushed.wait();
    }
}

void
CTCPSocket::shutdownInput()
{
    bool useNewJob = false;
    {
        CLock lock(&m_mutex);

        // shutdown socket for reading
        try {
            ARCH->closeSocketForRead(m_socket);
        }
        catch (XArchNetwork&) {
            // ignore
        }

        // shutdown buffer for reading
        if (m_readable) {
            sendEvent(getInputShutdownEvent());
            onInputShutdown();
            useNewJob = true;
        }
    }
    if (useNewJob) {
        setJob(newJob());
    }
}

void
CTCPSocket::shutdownOutput()
{
    bool useNewJob = false;
    {
        CLock lock(&m_mutex);

        // shutdown socket for writing
        try {
            ARCH->closeSocketForWrite(m_socket);
        }
        catch (XArchNetwork&) {
            // ignore
        }

        // shutdown buffer for writing
        if (m_writable) {
            sendEvent(getOutputShutdownEvent());
            onOutputShutdown();
            useNewJob = true;
        }
    }
    if (useNewJob) {
        setJob(newJob());
    }
}

bool
CTCPSocket::isReady() const
{
    CLock lock(&m_mutex);
    return (m_inputBuffer.getSize() > 0);
}

UInt32
CTCPSocket::getSize() const
{
    CLock lock(&m_mutex);
    return m_inputBuffer.getSize();
}

void
CTCPSocket::connect(const CNetworkAddress& addr)
{
    {
        CLock lock(&m_mutex);

        // fail on attempts to reconnect
        if (m_socket == NULL || m_connected) {
            sendConnectionFailedEvent("busy");
            return;
        }

        try {
            if (ARCH->connectSocket(m_socket, addr.getAddress())) {
                sendEvent(getConnectedEvent());
                onConnected();
            }
            else {
                // connection is in progress
                m_writable = true;
            }
        }
        catch (XArchNetwork& e) {
            throw XSocketConnect(e.what());
        }
    }
    setJob(newJob());
}

void
CTCPSocket::init()
{
    // default state
    m_connected = false;
    m_readable  = false;
    m_writable  = false;

    try {
        // turn off Nagle algorithm.  we send lots of very short messages
        // that should be sent without (much) delay.  for example, the
        // mouse motion messages are much less useful if they're delayed.
        ARCH->setNoDelayOnSocket(m_socket, true);
    }
    catch (XArchNetwork& e) {
        try {
            ARCH->closeSocket(m_socket);
            m_socket = NULL;
        }
        catch (XArchNetwork&) {
            // ignore
        }
        throw XSocketCreate(e.what());
    }
}

void
CTCPSocket::setJob(ISocketMultiplexerJob* job)
{
    // multiplexer will delete the old job
    if (job == NULL) {
        CSocketMultiplexer::getInstance()->removeSocket(this);
    }
    else {
        CSocketMultiplexer::getInstance()->addSocket(this, job);
    }
}

ISocketMultiplexerJob*
CTCPSocket::newJob()
{
    // note -- must have m_mutex locked on entry

    if (m_socket == NULL) {
        return NULL;
    }
    else if (!m_connected) {
        assert(!m_readable);
        if (!(m_readable || m_writable)) {
            return NULL;
        }
        return new TSocketMultiplexerMethodJob<CTCPSocket>(
                                this, &CTCPSocket::serviceConnecting,
                                m_socket, m_readable, m_writable);
    }
    else {
        if (!(m_readable || (m_writable && (m_outputBuffer.getSize() > 0)))) {
            return NULL;
        }
        return new TSocketMultiplexerMethodJob<CTCPSocket>(
                                this, &CTCPSocket::serviceConnected,
                                m_socket, m_readable,
                                m_writable && (m_outputBuffer.getSize() > 0));
    }
}

void
CTCPSocket::sendConnectionFailedEvent(const char* msg)
{
    CConnectionFailedInfo* info = new CConnectionFailedInfo(msg);
    EVENTQUEUE->addEvent(CEvent(getConnectionFailedEvent(),
                            getEventTarget(), info, CEvent::kDontFreeData));
}

void
CTCPSocket::sendEvent(CEvent::Type type)
{
    EVENTQUEUE->addEvent(CEvent(type, getEventTarget(), NULL));
}

void
CTCPSocket::onConnected()
{
    m_connected = true;
    m_readable  = true;
    m_writable  = true;
}

void
CTCPSocket::onInputShutdown()
{
    m_inputBuffer.pop(m_inputBuffer.getSize());
    m_readable = false;
}

void
CTCPSocket::onOutputShutdown()
{
    m_outputBuffer.pop(m_outputBuffer.getSize());
    m_writable = false;

    // we're now flushed
    m_flushed = true;
    m_flushed.broadcast();
}

void
CTCPSocket::onDisconnected()
{
    // disconnected
    onInputShutdown();
    onOutputShutdown();
    m_connected = false;
}

ISocketMultiplexerJob*
CTCPSocket::serviceConnecting(ISocketMultiplexerJob* job,
                bool, bool write, bool error)
{
    CLock lock(&m_mutex);

    // should only check for errors if error is true but checking a new
    // socket (and a socket that's connecting should be new) for errors
    // should be safe and Mac OS X appears to have a bug where a
    // non-blocking stream socket that fails to connect immediately is
    // reported by select as being writable (i.e. connected) even when
    // the connection has failed.  this is easily demonstrated on OS X
    // 10.3.4 by starting a synergy client and telling to connect to
    // another system that's not running a synergy server.  it will
    // claim to have connected then quickly disconnect (i guess because
    // read returns 0 bytes).  unfortunately, synergy attempts to
    // reconnect immediately, the process repeats and we end up
    // spinning the CPU.  luckily, OS X does set SO_ERROR on the
    // socket correctly when the connection has failed so checking for
    // errors works.  (curiously, sometimes OS X doesn't report
    // connection refused.  when that happens it at least doesn't
    // report the socket as being writable so synergy is able to time
    // out the attempt.)
    if (error || true) {
        try {
            // connection may have failed or succeeded
            ARCH->throwErrorOnSocket(m_socket);
        }
        catch (XArchNetwork& e) {
            sendConnectionFailedEvent(e.what().c_str());
            onDisconnected();
            return newJob();
        }
    }

    if (write) {
        sendEvent(getConnectedEvent());
        onConnected();
        return newJob();
    }

    return job;
}

ISocketMultiplexerJob*
CTCPSocket::serviceConnected(ISocketMultiplexerJob* job,
                bool read, bool write, bool error)
{
    CLock lock(&m_mutex);

    if (error) {
        sendEvent(getDisconnectedEvent());
        onDisconnected();
        return newJob();
    }

    bool needNewJob = false;

    if (write) {
        try {
            // write data
            UInt32 n = m_outputBuffer.getSize();
            const void* buffer = m_outputBuffer.peek(n);
            n = (UInt32)ARCH->writeSocket(m_socket, buffer, n);

            // discard written data
            if (n > 0) {
                m_outputBuffer.pop(n);
                if (m_outputBuffer.getSize() == 0) {
                    sendEvent(getOutputFlushedEvent());
                    m_flushed = true;
                    m_flushed.broadcast();
                    needNewJob = true;
                }
            }
        }
        catch (XArchNetworkShutdown&) {
            // remote read end of stream hungup.  our output side
            // has therefore shutdown.
            onOutputShutdown();
            sendEvent(getOutputShutdownEvent());
            if (!m_readable && m_inputBuffer.getSize() == 0) {
                sendEvent(getDisconnectedEvent());
                m_connected = false;
            }
            needNewJob = true;
        }
        catch (XArchNetworkDisconnected&) {
            // stream hungup
            onDisconnected();
            sendEvent(getDisconnectedEvent());
            needNewJob = true;
        }
        catch (XArchNetwork& e) {
            // other write error
            LOG((CLOG_WARN "error writing socket: %s", e.what().c_str()));
            onDisconnected();
            sendEvent(getOutputErrorEvent());
            sendEvent(getDisconnectedEvent());
            needNewJob = true;
        }
    }

    if (read && m_readable) {
        try {
            UInt8 buffer[4096];
            size_t n = ARCH->readSocket(m_socket, buffer, sizeof(buffer));
            if (n > 0) {
                bool wasEmpty = (m_inputBuffer.getSize() == 0);

                // slurp up as much as possible
                do {
                    m_inputBuffer.write(buffer, (UInt32)n);
                    n = ARCH->readSocket(m_socket, buffer, sizeof(buffer));
                } while (n > 0);

                // send input ready if input buffer was empty
                if (wasEmpty) {
                    sendEvent(getInputReadyEvent());
                }
            }
            else {
                // remote write end of stream hungup.  our input side
                // has therefore shutdown but don't flush our buffer
                // since there's still data to be read.
                sendEvent(getInputShutdownEvent());
                if (!m_writable && m_inputBuffer.getSize() == 0) {
                    sendEvent(getDisconnectedEvent());
                    m_connected = false;
                }
                m_readable = false;
                needNewJob = true;
            }
        }
        catch (XArchNetworkDisconnected&) {
            // stream hungup
            sendEvent(getDisconnectedEvent());
            onDisconnected();
            needNewJob = true;
        }
        catch (XArchNetwork& e) {
            // ignore other read error
            LOG((CLOG_WARN "error reading socket: %s", e.what().c_str()));
        }
    }

    return needNewJob ? newJob() : job;
}