// Copyright (C) 2016 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

// Qt-Security score:significant reason:default

//#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. When the client connection has been added

    to the pending connection queue using the addPendingConnection()

    function, the pendingConnectionAvailable() signal is emitted.

    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}, {Threaded Fortune Server},

        {Torrent Example}

*/

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

    This signal is emitted every time a new connection is available, regardless

    of whether it has been added to the pending connections queue or not.

    \sa hasPendingConnections(), nextPendingConnection()

*/

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

    This signal is emitted every time a new connection has been added to the

    pending connections queue.

    \sa hasPendingConnections(), nextPendingConnection()

    \since 6.4

*/

/*! \fn void QTcpServer::acceptError(QAbstractSocket::SocketError socketError)

    \since 5.0

    This signal is emitted when accepting a new connection results in an error.

    The \a socketError parameter describes the type of error that occurred.

    \sa pauseAccepting(), resumeAccepting()

*/

#include "qtcpserver.h"

#include "qtcpserver_p.h"

#include "qalgorithms.h"

#include "qhostaddress.h"

#include "qlist.h"

#include "qpointer.h"

#include "qabstractsocketengine_p.h"

#include "qtcpsocket.h"

#include "qnetworkproxy.h"

QT_BEGIN_NAMESPACE

#define Q_CHECK_SOCKETENGINE(returnValue) do { \

    if (!d->socketEngine) { \

        return returnValue; \

    } } while (0)

/*! \internal

*/

QTcpServerPrivate::QTcpServerPrivate()

 : port(0)

 , socketType(QAbstractSocket::UnknownSocketType)

 , state(QAbstractSocket::UnconnectedState)

 , socketEngine(nullptr)

 , 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.isLoopback())

        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(),

                                 socketType == QAbstractSocket::SctpSocket ?

                                 QNetworkProxyQuery::SctpServer :

                                 QNetworkProxyQuery::TcpServer);

        proxies = QNetworkProxyFactory::proxyForQuery(query);

    }

    // return the first that we can use

    for (const QNetworkProxy &p : std::as_const(proxies)) {

        if (socketType == QAbstractSocket::TcpSocket &&

            (p.capabilities() & QNetworkProxy::ListeningCapability) != 0)

            return p;

        if (socketType == QAbstractSocket::SctpSocket &&

            (p.capabilities() & QNetworkProxy::SctpListeningCapability) != 0)

            return p;

    }

    // no proxy found

    // DefaultProxy will raise an error

    return QNetworkProxy(QNetworkProxy::DefaultProxy);

}

#endif

/*! \internal

*/

void QTcpServerPrivate::configureCreatedSocket()

{

#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.

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

#endif

}

/*! \internal

*/

void QTcpServerPrivate::readNotification()

{

    Q_Q(QTcpServer);

    for (;;) {

        if (totalPendingConnections() >= maxConnections) {

#if defined (QTCPSERVER_DEBUG)

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

#endif

            if (socketEngine->isReadNotificationEnabled())

                socketEngine->setReadNotificationEnabled(false);

            return;

        }

        qintptr descriptor = socketEngine->accept();

        if (descriptor == -1) {

            if (socketEngine->error() != QAbstractSocket::TemporaryError) {

                q->pauseAccepting();

                serverSocketError = socketEngine->error();

                serverSocketErrorString = socketEngine->errorString();

                emit q->acceptError(serverSocketError);

            }

            break;

        }

#if defined (QTCPSERVER_DEBUG)

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

#endif

        QPointer<QTcpServer> that = q;

        q->incomingConnection(descriptor);

        if (that)

            emit q->newConnection();

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

            return;

    }

}

/*!

    \internal

    Return the amount of sockets currently in queue for the server.

    This is to make maxPendingConnections work properly with servers that don't

    necessarily have 'ready-to-go' sockets as soon as they connect,

    e.g. QSslServer.

    By default we just return pendingConnections.size(), which is equivalent to

    what it did before.

*/

int QTcpServerPrivate::totalPendingConnections() const

{

    return int(pendingConnections.size());

}

/*!

    Constructs a QTcpServer object.

    \a parent is passed to the QObject constructor.

    \sa listen(), setSocketDescriptor()

*/

QTcpServer::QTcpServer(QObject *parent)

    : QObject(*new QTcpServerPrivate, parent)

{

    Q_D(QTcpServer);

#if defined(QTCPSERVER_DEBUG)

    qDebug("QTcpServer::QTcpServer(%p)", parent);

#endif

    d->socketType = QAbstractSocket::TcpSocket;

}

/*!

    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()

{

#if defined(QTCPSERVER_DEBUG)

    qDebug("QTcpServer::~QTcpServer()");

#endif

    close();

}

/*! \internal

    Constructs a new server object with socket of type \a socketType. The \a

    parent argument is passed to QObject's constructor.

*/

QTcpServer::QTcpServer(QAbstractSocket::SocketType socketType, QTcpServerPrivate &dd,

                       QObject *parent) : QObject(dd, parent)

{

    Q_D(QTcpServer);

#if defined(QTCPSERVER_DEBUG)

    qDebug("QTcpServer::QTcpServer(%sSocket, QTcpServerPrivate == %p, parent == %p)",

           socketType == QAbstractSocket::TcpSocket ? "Tcp"

           : socketType == QAbstractSocket::UdpSocket ? "Udp"

           : socketType == QAbstractSocket::SctpSocket ? "Sctp"

           : "Unknown", &dd, parent);

#endif

    d->socketType = socketType;

}

/*!

    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 \c true on success; otherwise returns \c 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();

    QHostAddress addr = address;

#ifdef QT_NO_NETWORKPROXY

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

#else

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

#endif

    delete d->socketEngine;

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

    if (!d->socketEngine) {

        d->serverSocketError = QAbstractSocket::UnsupportedSocketOperationError;

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

        return false;

    }

    if (!d->socketEngine->initialize(d->socketType, proto)) {

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

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

        return false;

    }

    proto = d->socketEngine->protocol();

    if (addr.protocol() == QAbstractSocket::AnyIPProtocol && proto == QAbstractSocket::IPv4Protocol)

        addr = QHostAddress::AnyIPv4;

    d->configureCreatedSocket();

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

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

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

        return false;

    }

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

        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 \c true if the server is currently listening for incoming

    connections; otherwise returns \c 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 = nullptr;

    }

    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()

*/

qintptr 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 \c true if

    the socket is set successfully; otherwise returns \c false.

    The socket is assumed to be in listening state.

    \sa socketDescriptor(), isListening()

*/

bool QTcpServer::setSocketDescriptor(qintptr 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) {

        d->serverSocketError = QAbstractSocket::UnsupportedSocketOperationError;

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

        return false;

    }

    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 \c true if a connection is

    available; otherwise returns \c false. If the operation timed out

    and \a timedOut is not \nullptr, *\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(QDeadlineTimer(msec), timedOut)) {

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

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

        return false;

    }

    if (timedOut && *timedOut)

        return false;

    d->readNotification();

    return true;

}

/*!

    Returns \c true if the server has a pending connection; otherwise

    returns \c 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.

    \nullptr 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,

    you need to override incomingConnection().

    \sa hasPendingConnections()

*/

QTcpSocket *QTcpServer::nextPendingConnection()

{

    Q_D(QTcpServer);

    if (d->pendingConnections.isEmpty())

        return nullptr;

    if (!d->socketEngine) {

        qWarning("QTcpServer::nextPendingConnection() called while not listening");

    } else if (!d->socketEngine->isReadNotificationEnabled()) {

        d->socketEngine->setReadNotificationEnabled(true);

    }

    return d->pendingConnections.takeFirst();

}

/*!

    This virtual function is called by QTcpServer when a new

    connection is available. The \a socketDescriptor argument is the

    native socket descriptor for the accepted connection.

    The base implementation creates a QTcpSocket, sets the socket

    descriptor and then stores the QTcpSocket in an internal list of

    pending connections. Finally newConnection() is emitted.

    Reimplement this function to alter the server's behavior when a

    connection is available.

    If this server is using QNetworkProxy then the \a socketDescriptor

    may not be usable with native socket functions, and should only be

    used with QTcpSocket::setSocketDescriptor().

    \note If another socket is created in the reimplementation

    of this method, it needs to be added to the Pending Connections mechanism

    by calling addPendingConnection().

    \note If you want to handle an incoming connection as a new QTcpSocket

    object in another thread you have to pass the socketDescriptor

    to the other thread and create the QTcpSocket object there and

    use its setSocketDescriptor() method.

    \sa newConnection(), nextPendingConnection(), addPendingConnection()

*/

void QTcpServer::incomingConnection(qintptr socketDescriptor)

{

#if defined (QTCPSERVER_DEBUG)

    qDebug("QTcpServer::incomingConnection(%i)", socketDescriptor);

#endif

    QTcpSocket *socket = new QTcpSocket(this);

    socket->setSocketDescriptor(socketDescriptor);

    addPendingConnection(socket);

}

/*!

    This function is called by QTcpServer::incomingConnection()

    to add the \a socket to the list of pending incoming connections.

    \note Don't forget to call this member from reimplemented

    incomingConnection() if you do not want to break the

    Pending Connections mechanism. This function emits the

    pendingConnectionAvailable() signal after the socket has been

    added.

    \sa incomingConnection(), pendingConnectionAvailable()

    \since 4.7

*/

void QTcpServer::addPendingConnection(QTcpSocket* socket)

{

    d_func()->pendingConnections.append(socket);

    emit pendingConnectionAvailable(QPrivateSignal());

}

/*!

    Sets the maximum number of pending accepted connections to \a

    numConnections. QTcpServer will accept no more than \a

    numConnections incoming connections before

    nextPendingConnection() is called. By default, the limit is 30

    pending connections.

    Clients may still able to connect after the server has reached

    its maximum number of pending connections (i.e., QTcpSocket can

    still emit the connected() signal). QTcpServer will stop

    accepting the new connections, but the operating system may

    still keep them in queue.

    \sa maxPendingConnections(), hasPendingConnections()

*/

void QTcpServer::setMaxPendingConnections(int numConnections)

{

    d_func()->maxConnections = numConnections;

}

/*!

    Returns the maximum number of pending accepted connections. The

    default is 30.

    \sa setMaxPendingConnections(), hasPendingConnections()

*/

int QTcpServer::maxPendingConnections() const

{

    return d_func()->maxConnections;

}

/*!

    Sets the backlog queue size of to be accepted connections to \a

    size. The operating system might reduce or ignore this value.

    By default, the queue size is 50.

    \note This property must be set prior to calling listen().

    \since 6.3

    \sa listenBacklogSize()

*/

void QTcpServer::setListenBacklogSize(int size)

{

    d_func()->listenBacklog = size;

}

/*!

    Returns the backlog queue size of to be accepted connections.

    \since 6.3

    \sa setListenBacklogSize()

*/

int QTcpServer::listenBacklogSize() const

{

    return d_func()->listenBacklog;

}

/*!

    Returns an error code for the last error that occurred.

    \sa errorString()

*/

QAbstractSocket::SocketError QTcpServer::serverError() const

{

    return d_func()->serverSocketError;

}

/*!

    Returns a human readable description of the last error that

    occurred.

    \sa serverError()

*/

QString QTcpServer::errorString() const

{

    return d_func()->serverSocketErrorString;

}

/*!

    \since 5.0

    Pauses accepting new connections. Queued connections will remain in queue.

    \sa resumeAccepting()

*/

void QTcpServer::pauseAccepting()

{

    d_func()->socketEngine->setReadNotificationEnabled(false);

}

/*!

    \since 5.0

    Resumes accepting new connections.

    \sa pauseAccepting()

*/

void QTcpServer::resumeAccepting()

{

    d_func()->socketEngine->setReadNotificationEnabled(true);

}

#ifndef QT_NO_NETWORKPROXY

/*!

    \since 4.1

    Sets the explicit network proxy for this socket to \a networkProxy.

    To disable the use of a proxy for this socket, use the

    QNetworkProxy::NoProxy proxy type:

    \snippet code/src_network_socket_qtcpserver.cpp 0

    \sa proxy(), QNetworkProxy

*/

void QTcpServer::setProxy(const QNetworkProxy &networkProxy)

{

    Q_D(QTcpServer);

    d->proxy = networkProxy;

}

/*!

    \since 4.1

    Returns the network proxy for this socket.

    By default QNetworkProxy::DefaultProxy is used.

    \sa setProxy(), QNetworkProxy

*/

QNetworkProxy QTcpServer::proxy() const

{

    Q_D(const QTcpServer);

    return d->proxy;

}

#endif // QT_NO_NETWORKPROXY

QT_END_NAMESPACE

#include "moc_qtcpserver.cpp"