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//#define QTCPSERVER_DEBUG

/*! \class QTcpServer

    \brief The QTcpServer class provides a TCP-based server.

    \reentrant

    \ingroup network

    \inmodule QtNetwork

    This class makes it possible to accept incoming TCP connections.

    You can specify the port or have QTcpServer pick one

    automatically. You can listen on a specific address or on all the

    machine's addresses.

    Call listen() to have the server listen for incoming connections.

    The newConnection() signal is then emitted each time a client

    connects to the server.

    Call nextPendingConnection() to accept the pending connection as

    a connected QTcpSocket. The function returns a pointer to a

    QTcpSocket in QAbstractSocket::ConnectedState that you can use for

    communicating with the client.

    If an error occurs, serverError() returns the type of error, and

    errorString() can be called to get a human readable description of

    what happened.

    When listening for connections, the address and port on which the

    server is listening are available as serverAddress() and

    serverPort().

    Calling close() makes QTcpServer stop listening for incoming

    connections.

    Although QTcpServer is mostly designed for use with an event

    loop, it's possible to use it without one. In that case, you must

    use waitForNewConnection(), which blocks until either a

    connection is available or a timeout expires.

    \sa QTcpSocket, {Fortune Server Example}, {Threaded Fortune Server Example},

        {Loopback Example}, {Torrent Example}

*/

/*! \fn void QTcpServer::newConnection()

    This signal is emitted every time a new connection is available.

    \sa hasPendingConnections(), nextPendingConnection()

*/

#include "private/qobject_p.h"

#include "qalgorithms.h"

#include "qhostaddress.h"

#include "qlist.h"

#include "qpointer.h"

#include "qnativesocketengine_p.h"

#include "qtcpserver.h"

#include "qtcpsocket.h"

#include "qnetworkproxy.h"

QT_BEGIN_NAMESPACE

#define Q_CHECK_SOCKETENGINE(returnValue) do { \

    if (!d->socketEngine) { \

        return returnValue; \

    } } while (0)

class QTcpServerPrivate : public QObjectPrivate, public QAbstractSocketEngineReceiver

{

    Q_DECLARE_PUBLIC(QTcpServer)

public:

    QTcpServerPrivate();

    ~QTcpServerPrivate();

    QList<QTcpSocket *> pendingConnections;

    quint16 port;

    QHostAddress address;

    QAbstractSocket::SocketState state;

    QAbstractSocketEngine *socketEngine;

    QAbstractSocket::SocketError serverSocketError;

    QString serverSocketErrorString;

    int maxConnections;

#ifndef QT_NO_NETWORKPROXY

    QNetworkProxy proxy;

    QNetworkProxy resolveProxy(const QHostAddress &address, quint16 port);

#endif

    // from QAbstractSocketEngineReceiver

    void readNotification();

    inline void writeNotification() {}

    inline void exceptionNotification() {}

    inline void connectionNotification() {}

#ifndef QT_NO_NETWORKPROXY

    inline void proxyAuthenticationRequired(const QNetworkProxy &, QAuthenticator *) {}

#endif

};

/*! \internal

*/

QTcpServerPrivate::QTcpServerPrivate()

 : port(0)

 , state(QAbstractSocket::UnconnectedState)

 , socketEngine(0)

 , serverSocketError(QAbstractSocket::UnknownSocketError)

 , maxConnections(30)

{

}

/*! \internal

*/

QTcpServerPrivate::~QTcpServerPrivate()

{

}

#ifndef QT_NO_NETWORKPROXY

/*! \internal

    Resolve the proxy to its final value.

*/

QNetworkProxy QTcpServerPrivate::resolveProxy(const QHostAddress &address, quint16 port)

{

    if (address == QHostAddress::LocalHost ||

        address == QHostAddress::LocalHostIPv6)

        return QNetworkProxy::NoProxy;

    QList<QNetworkProxy> proxies;

    if (proxy.type() != QNetworkProxy::DefaultProxy) {

        // a non-default proxy was set with setProxy

        proxies << proxy;

    } else {

        // try the application settings instead

        QNetworkProxyQuery query(port, QString(), QNetworkProxyQuery::TcpServer);

        proxies = QNetworkProxyFactory::proxyForQuery(query);

    }

    // return the first that we can use

    foreach (const QNetworkProxy &p, proxies) {

        if (p.capabilities() & QNetworkProxy::ListeningCapability)

            return p;

    }

    // no proxy found

    // DefaultProxy will raise an error

    return QNetworkProxy(QNetworkProxy::DefaultProxy);

}

#endif

/*! \internal

*/

void QTcpServerPrivate::readNotification()

{

    Q_Q(QTcpServer);

    for (;;) {

        if (pendingConnections.count() >= maxConnections) {

#if defined (QTCPSERVER_DEBUG)

            qDebug("QTcpServerPrivate::_q_processIncomingConnection() too many connections");

#endif

            if (socketEngine->isReadNotificationEnabled())

                socketEngine->setReadNotificationEnabled(false);

            return;

        }

        int descriptor = socketEngine->accept();

        if (descriptor == -1)

            break;

#if defined (QTCPSERVER_DEBUG)

        qDebug("QTcpServerPrivate::_q_processIncomingConnection() accepted socket %i", descriptor);

#endif

        q->incomingConnection(descriptor);

        QPointer<QTcpServer> that = q;

        emit q->newConnection();

        if (!that || !q->isListening())

            return;

    }

}

/*!

    Constructs a QTcpServer object.

    \a parent is passed to the QObject constructor.

    \sa listen(), setSocketDescriptor()

*/

QTcpServer::QTcpServer(QObject *parent)

    : QObject(*new QTcpServerPrivate, parent)

{

}

/*!

    Destroys the QTcpServer object. If the server is listening for

    connections, the socket is automatically closed.

    Any client \l{QTcpSocket}s that are still connected must either

    disconnect or be reparented before the server is deleted.

    \sa close()

*/

QTcpServer::~QTcpServer()

{

    close();

}

/*!

    Tells the server to listen for incoming connections on address \a

    address and port \a port. If \a port is 0, a port is chosen

    automatically. If \a address is QHostAddress::Any, the server

    will listen on all network interfaces.

    Returns true on success; otherwise returns false.

    \sa isListening()

*/

bool QTcpServer::listen(const QHostAddress &address, quint16 port)

{

    Q_D(QTcpServer);

    if (d->state == QAbstractSocket::ListeningState) {

        qWarning("QTcpServer::listen() called when already listening");

        return false;

    }

    QAbstractSocket::NetworkLayerProtocol proto = address.protocol();

#ifdef QT_NO_NETWORKPROXY

    static const QNetworkProxy &proxy = *(QNetworkProxy *)0;

#else

    QNetworkProxy proxy = d->resolveProxy(address, port);

#endif

    delete d->socketEngine;

    d->socketEngine = QAbstractSocketEngine::createSocketEngine(QAbstractSocket::TcpSocket, proxy, this);

    if (!d->socketEngine) {

        d->serverSocketError = QAbstractSocket::UnsupportedSocketOperationError;

        d->serverSocketErrorString = tr("Operation on socket is not supported");

        return false;

    }

    if (!d->socketEngine->initialize(QAbstractSocket::TcpSocket, proto)) {

        d->serverSocketError = d->socketEngine->error();

        d->serverSocketErrorString = d->socketEngine->errorString();

        return false;

    }

#if defined(Q_OS_UNIX)

    // Under Unix, we want to be able to bind to the port, even if a socket on

    // the same address-port is in TIME_WAIT. Under Windows this is possible

    // anyway -- furthermore, the meaning of reusable on Windows is different:

    // it means that you can use the same address-port for multiple listening

    // sockets.

    // Don't abort though if we can't set that option. For example the socks

    // engine doesn't support that option, but that shouldn't prevent us from

    // trying to bind/listen.

    d->socketEngine->setOption(QAbstractSocketEngine::AddressReusable, 1);

#endif

    if (!d->socketEngine->bind(address, port)) {

        d->serverSocketError = d->socketEngine->error();

        d->serverSocketErrorString = d->socketEngine->errorString();

        return false;

    }

    if (!d->socketEngine->listen()) {

        d->serverSocketError = d->socketEngine->error();

        d->serverSocketErrorString = d->socketEngine->errorString();

        return false;

    }

    d->socketEngine->setReceiver(d);

    d->socketEngine->setReadNotificationEnabled(true);

    d->state = QAbstractSocket::ListeningState;

    d->address = d->socketEngine->localAddress();

    d->port = d->socketEngine->localPort();

#if defined (QTCPSERVER_DEBUG)

    qDebug("QTcpServer::listen(%i, \"%s\") == true (listening on port %i)", port,

           address.toString().toLatin1().constData(), d->socketEngine->localPort());

#endif

    return true;

}

/*!

    Returns true if the server is currently listening for incoming

    connections; otherwise returns false.

    \sa listen()

*/

bool QTcpServer::isListening() const

{

    Q_D(const QTcpServer);

    Q_CHECK_SOCKETENGINE(false);

    return d->socketEngine->state() == QAbstractSocket::ListeningState;

}

/*!

    Closes the server. The server will no longer listen for incoming

    connections.

    \sa listen()

*/

void QTcpServer::close()

{

    Q_D(QTcpServer);

    qDeleteAll(d->pendingConnections);

    d->pendingConnections.clear();

    if (d->socketEngine) {

        d->socketEngine->close();

        QT_TRY {

            d->socketEngine->deleteLater();

        } QT_CATCH(const std::bad_alloc &) {

            // in out of memory situations, the socketEngine

            // will be deleted in ~QTcpServer (it's a child-object of this)

        }

        d->socketEngine = 0;

    }

    d->state = QAbstractSocket::UnconnectedState;

}

/*!

    Returns the native socket descriptor the server uses to listen

    for incoming instructions, or -1 if the server is not listening.

    If the server is using QNetworkProxy, the returned descriptor may

    not be usable with native socket functions.

    \sa setSocketDescriptor(), isListening()

*/

int QTcpServer::socketDescriptor() const

{

    Q_D(const QTcpServer);

    Q_CHECK_SOCKETENGINE(-1);

    return d->socketEngine->socketDescriptor();

}

/*!

    Sets the socket descriptor this server should use when listening

    for incoming connections to \a socketDescriptor. Returns true if

    the socket is set successfully; otherwise returns false.

    The socket is assumed to be in listening state.

    \sa socketDescriptor(), isListening()

*/

bool QTcpServer::setSocketDescriptor(int socketDescriptor)

{

    Q_D(QTcpServer);

    if (isListening()) {

        qWarning("QTcpServer::setSocketDescriptor() called when already listening");

        return false;

    }

    if (d->socketEngine)

        delete d->socketEngine;

    d->socketEngine = QAbstractSocketEngine::createSocketEngine(socketDescriptor, this);

    if (!d->socketEngine->initialize(socketDescriptor, QAbstractSocket::ListeningState)) {

        d->serverSocketError = d->socketEngine->error();

        d->serverSocketErrorString = d->socketEngine->errorString();

#if defined (QTCPSERVER_DEBUG)

        qDebug("QTcpServer::setSocketDescriptor(%i) failed (%s)", socketDescriptor,

               d->serverSocketErrorString.toLatin1().constData());

#endif

        return false;

    }

    d->socketEngine->setReceiver(d);

    d->socketEngine->setReadNotificationEnabled(true);

    d->state = d->socketEngine->state();

    d->address = d->socketEngine->localAddress();

    d->port = d->socketEngine->localPort();

#if defined (QTCPSERVER_DEBUG)

    qDebug("QTcpServer::setSocketDescriptor(%i) succeeded.", socketDescriptor);

#endif

    return true;

}

/*!

    Returns the server's port if the server is listening for

    connections; otherwise returns 0.

    \sa serverAddress(), listen()

*/

quint16 QTcpServer::serverPort() const

{

    Q_D(const QTcpServer);

    Q_CHECK_SOCKETENGINE(0);

    return d->socketEngine->localPort();

}

/*!

    Returns the server's address if the server is listening for

    connections; otherwise returns QHostAddress::Null.

    \sa serverPort(), listen()

*/

QHostAddress QTcpServer::serverAddress() const

{

    Q_D(const QTcpServer);

    Q_CHECK_SOCKETENGINE(QHostAddress(QHostAddress::Null));

    return d->socketEngine->localAddress();

}

/*!

    Waits for at most \a msec milliseconds or until an incoming

    connection is available. Returns true if a connection is

    available; otherwise returns false. If the operation timed out

    and \a timedOut is not 0, *\a timedOut will be set to true.

    This is a blocking function call. Its use is disadvised in a

    single-threaded GUI application, since the whole application will

    stop responding until the function returns.

    waitForNewConnection() is mostly useful when there is no event

    loop available.

    The non-blocking alternative is to connect to the newConnection()

    signal.

    If msec is -1, this function will not time out.

    \sa hasPendingConnections(), nextPendingConnection()

*/

bool QTcpServer::waitForNewConnection(int msec, bool *timedOut)

{

    Q_D(QTcpServer);

    if (d->state != QAbstractSocket::ListeningState)

        return false;

    if (!d->socketEngine->waitForRead(msec, timedOut)) {

        d->serverSocketError = d->socketEngine->error();

        d->serverSocketErrorString = d->socketEngine->errorString();

        return false;

    }

    if (timedOut && *timedOut)

        return false;

    d->readNotification();

    return true;

}

/*!

    Returns true if the server has a pending connection; otherwise

    returns false.

    \sa nextPendingConnection(), setMaxPendingConnections()

*/

bool QTcpServer::hasPendingConnections() const

{

    return !d_func()->pendingConnections.isEmpty();

}

/*!

    Returns the next pending connection as a connected QTcpSocket

    object.

    The socket is created as a child of the server, which means that

    it is automatically deleted when the QTcpServer object is

    destroyed. It is still a good idea to delete the object

    explicitly when you are done with it, to avoid wasting memory.

    0 is returned if this function is called when there are no pending

    connections.

    \note The returned QTcpSocket object cannot be used from another

    thread. If you want to use an incoming connection from another thread,