Long live Qt!

1 files changed, 1518 insertions, 0 deletions

diff --git a/src/qt3support/network/q3socket.cpp b/src/qt3support/network/q3socket.cpp
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+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the Qt3Support module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "q3socket.h"
+#ifndef QT_NO_NETWORK
+#include "q3ptrlist.h"
+#include "qtimer.h"
+#include "q3socketdevice.h"
+#include "q3dns.h"
+#include "private/q3membuf_p.h"
+
+#include <string.h>
+#ifndef NO_ERRNO_H
+#if defined(Q_OS_WINCE)
+#include "qfunctions_wince.h"
+#else
+#include <errno.h>
+#endif
+#endif
+
+QT_BEGIN_NAMESPACE
+
+//#define Q3SOCKET_DEBUG
+
+/*
+  Perhaps this private functionality needs to be refactored.
+
+  Comment from Robert D Gatlin (Intel):
+
+    It would be nice to have the functionality inherent in Q3Socket available
+    as a separate class as a standard part of the Qt library, something along
+    the line of:
+
+      class QByteBuffer : public QIODevice { ... }
+
+    The same class could/would be used within Q3Socket for the Read/Write
+    buffers.
+
+    The above class could be used in the following way(s):
+
+	buffer.open( IO_WriteOnly | IO_Append );
+	buffer.writeBlock( a ); // a = QByteArray
+	buffer.close();
+
+	QByteArray b;
+	b.resize( buffer.size() );
+	buffer.open( IO_ReadOnly );
+	buffer.readBlock( b.data(), b.size() );
+	buffer.close();
+
+    But would also be useable with QDataStream (via QIODevice) with:
+
+	buffer.open( IO_WriteOnly | IO_Append );
+	QDataStream is( &buffer );
+	is << 100;
+	buffer.close();
+
+	buffer.open( IO_ReadOnly );
+	QDataStream os( &buffer );
+	Q_UINT32 x;
+	os >> x;
+	buffer.close();
+
+    The real usefulness is with any situations where data (QByteArray) arrives
+    incrementally (as in Q3Socket and filter case above).
+
+    I tried using QBuffer, but QBuffer does not trim bytes from the front of
+    the buffer in cases like:
+
+	QBuffer buf;
+	buf.open( IO_ReadOnly );
+	QDataStream ds( &buf );
+	Q_INT32 x;
+	ds >> x;
+	buf.close();
+
+    In the above case, buf.size() will be identical before and after the
+    operation with QDataStream. Based on the implementation of QBuffer, it
+    does not appear well suited for this kind of operation.
+*/
+
+// Private class for Q3Socket
+
+class Q3SocketPrivate {
+public:
+    Q3SocketPrivate();
+   ~Q3SocketPrivate();
+    void closeSocket();
+    void close();
+    void connectionClosed();
+    void setSocketDevice( Q3Socket *q, Q3SocketDevice *device );
+
+    Q3Socket::State	state;			// connection state
+    QString		host;			// host name
+    Q_UINT16		port;			// host port
+    Q3SocketDevice      *socket;			// connection socket
+    QSocketNotifier     *rsn, *wsn;		// socket notifiers
+    Q3Membuf		rba;			// read buffer
+    Q_ULONG		readBufferSize;		// limit for the read buffer size
+    Q3PtrList<QByteArray> wba;			// list of write bufs
+    QHostAddress	addr;			// connection address
+    Q3ValueList<QHostAddress> addresses;		// alternatives looked up
+    QIODevice::Offset	wsize;			// write total buf size
+    QIODevice::Offset	windex;			// write index
+#ifndef QT_NO_DNS
+    Q3Dns	       *dns4;
+    Q3Dns	       *dns6;
+#endif
+    static Q3PtrList<Q3Socket> sn_read_alreadyCalled; // used to avoid unwanted recursion
+    Q3ValueList<QHostAddress> l4;
+    Q3ValueList<QHostAddress> l6;
+};
+
+Q3PtrList<Q3Socket> Q3SocketPrivate::sn_read_alreadyCalled;
+
+Q3SocketPrivate::Q3SocketPrivate()
+    : state(Q3Socket::Idle), host(QString::fromLatin1("")), port(0),
+      socket(0), rsn(0), wsn(0), readBufferSize(0), wsize(0), windex(0)
+{
+#ifndef QT_NO_DNS
+    dns4 = 0;
+    dns6 = 0;
+#endif
+    wba.setAutoDelete( true );
+}
+
+Q3SocketPrivate::~Q3SocketPrivate()
+{
+    close();
+    delete socket;
+#ifndef QT_NO_DNS
+    delete dns4;
+    delete dns6;
+#endif
+}
+
+extern void qDeleteInEventHandler(QObject *o);
+void Q3SocketPrivate::closeSocket()
+{
+    // Order is important here - the socket notifiers must go away
+    // before the socket does, otherwise libc or the kernel will
+    // become unhappy.
+    if (rsn) {
+        qDeleteInEventHandler(rsn);
+        rsn = 0;
+    }
+    if (wsn) {
+        qDeleteInEventHandler(wsn);
+        wsn = 0;
+    }
+    if ( socket )
+	socket->close();
+}
+
+void Q3SocketPrivate::close()
+{
+    closeSocket();
+    wsize = 0;
+    rba.clear(); wba.clear();
+    windex = 0;
+}
+
+void Q3SocketPrivate::connectionClosed()
+{
+    // We keep the open state in case there's unread incoming data
+    state = Q3Socket::Idle;
+    closeSocket();
+    wba.clear();
+    windex = wsize = 0;
+}
+
+void Q3SocketPrivate::setSocketDevice( Q3Socket *q, Q3SocketDevice *device )
+{
+    delete socket;
+    delete rsn;
+    delete wsn;
+
+    if ( device ) {
+	socket = device;
+    } else {
+	socket = new Q3SocketDevice( Q3SocketDevice::Stream,
+				    ( addr.isIPv4Address() ?
+				      Q3SocketDevice::IPv4 :
+				      Q3SocketDevice::IPv6 ), 0 );
+	socket->setBlocking( false );
+	socket->setAddressReusable( true );
+    }
+
+    rsn = new QSocketNotifier( socket->socket(),
+			       QSocketNotifier::Read, q, "read" );
+    wsn = new QSocketNotifier( socket->socket(),
+			       QSocketNotifier::Write, q, "write" );
+
+    QObject::connect( rsn, SIGNAL(activated(int)), q, SLOT(sn_read()) );
+    rsn->setEnabled( false );
+    QObject::connect( wsn, SIGNAL(activated(int)), q, SLOT(sn_write()) );
+    wsn->setEnabled( false );
+}
+
+/*!
+    \class Q3Socket
+    \brief The Q3Socket class provides a buffered TCP connection.
+
+    \compat
+
+    It provides a totally non-blocking QIODevice, and modifies and
+    extends the API of QIODevice with socket-specific code.
+
+    The functions you're likely to call most are connectToHost(),
+    bytesAvailable(), canReadLine() and the ones it inherits from
+    QIODevice.
+
+    connectToHost() is the most-used function. As its name implies,
+    it opens a connection to a named host.
+
+    Most network protocols are either packet-oriented or
+    line-oriented. canReadLine() indicates whether a connection
+    contains an entire unread line or not, and bytesAvailable()
+    returns the number of bytes available for reading.
+
+    The signals error(), connected(), readyRead() and
+    connectionClosed() inform you of the progress of the connection.
+    There are also some less commonly used signals. hostFound() is
+    emitted when connectToHost() has finished its DNS lookup and is
+    starting its TCP connection. delayedCloseFinished() is emitted
+    when close() succeeds. bytesWritten() is emitted when Q3Socket
+    moves data from its "to be written" queue into the TCP
+    implementation.
+
+    There are several access functions for the socket: state() returns
+    whether the object is idle, is doing a DNS lookup, is connecting,
+    has an operational connection, etc. address() and port() return
+    the IP address and port used for the connection. The peerAddress()
+    and peerPort() functions return the IP address and port used by
+    the peer, and peerName() returns the name of the peer (normally
+    the name that was passed to connectToHost()). socketDevice()
+    returns a pointer to the Q3SocketDevice used for this socket.
+
+    Q3Socket inherits QIODevice, and reimplements some functions. In
+    general, you can treat it as a QIODevice for writing, and mostly
+    also for reading. The match isn't perfect, since the QIODevice
+    API is designed for devices that are controlled by the same
+    machine, and an asynchronous peer-to-peer network connection isn't
+    quite like that. For example, there is nothing that matches
+    QIODevice::size() exactly. The documentation for open(), close(),
+    flush(), size(), at(), atEnd(), readBlock(), writeBlock(),
+    getch(), putch(), ungetch() and readLine() describes the
+    differences in detail.
+
+    \warning Q3Socket is not suitable for use in threads. If you need
+    to uses sockets in threads use the lower-level Q3SocketDevice class.
+
+    \sa Q3SocketDevice, QHostAddress, QSocketNotifier
+*/
+
+
+/*!
+    Creates a Q3Socket object in Q3Socket::Idle state.
+
+    The \a parent and \a name arguments are passed on to the QObject
+    constructor.
+*/
+
+Q3Socket::Q3Socket( QObject *parent, const char *name )
+    : QIODevice( parent )
+{
+    setObjectName(QLatin1String(name));
+    d = new Q3SocketPrivate;
+    setSocketDevice( 0 );
+    resetStatus();
+}
+
+
+/*!
+    Destroys the socket. Closes the connection if necessary.
+
+    \sa close()
+*/
+
+Q3Socket::~Q3Socket()
+{
+#if defined(Q3SOCKET_DEBUG)
+    qDebug( "Q3Socket (%s): Destroy", name() );
+#endif
+    if ( state() != Idle )
+	close();
+    Q_ASSERT( d != 0 );
+    delete d;
+}
+
+
+/*!
+    Returns a pointer to the internal socket device.
+
+    There is normally no need to manipulate the socket device directly
+    since this class does the necessary setup for most applications.
+*/
+
+Q3SocketDevice *Q3Socket::socketDevice()
+{
+    return d->socket;
+}
+
+/*!
+    Sets the internal socket device to \a device. Passing a \a device
+    of 0 will cause the internal socket device to be used. Any
+    existing connection will be disconnected before using the new \a
+    device.
+
+    The new device should not be connected before being associated
+    with a Q3Socket; after setting the socket call connectToHost() to
+    make the connection.
+
+    This function is useful if you need to subclass Q3SocketDevice and
+    want to use the Q3Socket API, for example, to implement Unix domain
+    sockets.
+*/
+
+void Q3Socket::setSocketDevice( Q3SocketDevice *device )
+{
+    if ( state() != Idle )
+	close();
+    d->setSocketDevice( this, device );
+}
+
+/*!
+    \enum Q3Socket::State
+
+    This enum defines the connection states:
+
+    \value Idle if there is no connection
+    \value HostLookup during a DNS lookup
+    \value Connecting during TCP connection establishment
+    \value Connected when there is an operational connection
+    \value Closing if the socket is closing down, but is not yet closed.
+    \omitvalue Connection
+*/
+
+/*!
+    Returns the current state of the socket connection.
+
+    \sa Q3Socket::State
+*/
+
+Q3Socket::State Q3Socket::state() const
+{
+    return d->state;
+}
+
+
+#ifndef QT_NO_DNS
+
+/*!
+    Attempts to make a connection to \a host on the specified \a port
+    and return immediately.
+
+    Any connection or pending connection is closed immediately, and
+    Q3Socket goes into the \c HostLookup state. When the lookup
+    succeeds, it emits hostFound(), starts a TCP connection and goes
+    into the \c Connecting state. Finally, when the connection
+    succeeds, it emits connected() and goes into the \c Connected
+    state. If there is an error at any point, it emits error().
+
+    \a host may be an IP address in string form, or it may be a DNS
+    name. Q3Socket will do a normal DNS lookup if required. Note that
+    \a port is in native byte order, unlike some other libraries.
+
+    \sa state()
+*/
+
+void Q3Socket::connectToHost( const QString &host, Q_UINT16 port )
+{
+#if defined(Q3SOCKET_DEBUG)
+    qDebug( "Q3Socket (%s)::connectToHost: host %s, port %d",
+	    name(), host.ascii(), port );
+#endif
+    setSocketIntern( -1 );
+    d->state = HostLookup;
+    d->host = host;
+    d->port = port;
+    d->dns4 = new Q3Dns( host, Q3Dns::A );
+    d->dns6 = new Q3Dns( host, Q3Dns::Aaaa );
+
+    // try if the address is already available (for faster connecting...)
+    tryConnecting();
+    if ( d->state == HostLookup ) {
+	connect( d->dns4, SIGNAL(resultsReady()),
+		 this, SLOT(tryConnecting()) );
+	connect( d->dns6, SIGNAL(resultsReady()),
+		 this, SLOT(tryConnecting()) );
+    }
+}
+
+#endif
+
+
+/*!
+    This private slots continues the connection process where
+    connectToHost() leaves off.
+*/
+
+void Q3Socket::tryConnecting()
+{
+#if defined(Q3SOCKET_DEBUG)
+    qDebug( "Q3Socket (%s)::tryConnecting()", name() );
+#endif
+    // ### this ifdef isn't correct - addresses() also does /etc/hosts and
+    // numeric-address-as-string handling.
+#ifndef QT_NO_DNS
+
+    if ( d->dns4 ) {
+	d->l4 = d->dns4->addresses();
+	if ( !d->l4.isEmpty() || !d->dns4->isWorking() ) {
+#if defined(Q3SOCKET_DEBUG)
+	    qDebug( "Q3Socket (%s)::tryConnecting: host %s, port %d: "
+		    "%d IPv4 addresses",
+		    name(), d->host.ascii(), d->port, d->l4.count() );
+#endif
+	    delete d->dns4;
+	    d->dns4 = 0;
+	}
+    }
+
+    if ( d->dns6 ) {
+	d->l6 = d->dns6->addresses();
+	if ( !d->l6.isEmpty() || !d->dns6->isWorking() ) {
+#if defined(Q3SOCKET_DEBUG)
+	    qDebug( "Q3Socket (%s)::tryConnecting: host %s, port %d: "
+		    "%d IPv6 addresses",
+		    name(), d->host.ascii(), d->port, d->l6.count() );
+#endif
+	    delete d->dns6;
+	    d->dns6 = 0;
+	}
+    }
+
+    if ( d->state == HostLookup ) {
+	if ( d->l4.isEmpty() && d->l6.isEmpty() &&
+	     !d->dns4 && !d->dns6 ) {
+	    // no results and we're not still looking: give up
+	    d->state = Idle;
+	    emit error( ErrHostNotFound );
+	    return;
+	}
+	if ( d->l4.isEmpty() && d->l6.isEmpty() ) {
+	    // no results (yet): try again later
+	    return;
+	}
+
+	// we've found something. press on with that. if we later find
+	// more, fine.
+	emit hostFound();
+	d->state = Connecting;
+    }
+
+    if ( d->state == Connecting ) {
+	d->addresses += d->l4;
+	d->addresses += d->l6;
+	d->l4.clear();
+	d->l6.clear();
+
+	// try one address at a time, falling back to the next one if
+	// there is a connection failure. (should also support a timeout,
+	// or do multiple TCP-level connects at a time, with staggered
+	// starts to avoid bandwidth waste and cause fewer
+	// "connect-and-abort" errors. but that later.)
+	bool stuck = true;
+	while( stuck ) {
+	    stuck = false;
+	    if ( d->socket &&
+		 d->socket->connect( d->addr, d->port ) == false ) {
+		if ( d->socket->error() == Q3SocketDevice::NoError ) {
+		    if ( d->wsn )
+			d->wsn->setEnabled( true );
+		    return; // not serious, try again later
+		}
+
+#if defined(Q3SOCKET_DEBUG)
+		qDebug( "Q3Socket (%s)::tryConnecting: "
+			"Gave up on IP address %s",
+			name(), d->socket->peerAddress().toString().ascii() );
+#endif
+		delete d->wsn;
+		d->wsn = 0;
+		delete d->rsn;
+		d->rsn = 0;
+		delete d->socket;
+		d->socket = 0;
+
+                if(d->addresses.isEmpty()) {
+                    emit error( ErrConnectionRefused );
+                    return;
+                }
+            }
+	    // if the host has more addresses, try another some.
+	    if ( d->socket == 0 && !d->addresses.isEmpty() ) {
+		d->addr = *d->addresses.begin();
+		d->addresses.remove( d->addresses.begin() );
+		d->setSocketDevice( this, 0 );
+		stuck = true;
+#if defined(Q3SOCKET_DEBUG)
+		qDebug( "Q3Socket (%s)::tryConnecting: Trying IP address %s",
+			name(), d->addr.toString().ascii() );
+#endif
+	    }
+	};
+
+	// The socket write notifier will fire when the connection succeeds
+	if ( d->wsn )
+	    d->wsn->setEnabled( true );
+    }
+#endif
+}
+
+/*!
+    \enum Q3Socket::Error
+
+    This enum specifies the possible errors:
+    \value ErrConnectionRefused if the connection was refused
+    \value ErrHostNotFound if the host was not found
+    \value ErrSocketRead if a read from the socket failed
+*/
+
+/*!
+    \fn void Q3Socket::error(int error)
+
+    This signal is emitted after an error occurred. The \a error parameter is
+    the \l Error value.
+*/
+
+/*!
+    \fn void Q3Socket::hostFound()
+
+    This signal is emitted after connectToHost() has been called and
+    the host lookup has succeeded.
+
+    \sa connected()
+*/
+
+
+/*!
+    \fn void Q3Socket::connected()
+
+    This signal is emitted after connectToHost() has been called and a
+    connection has been successfully established.
+
+    \sa connectToHost(), connectionClosed()
+*/
+
+
+/*!
+    \fn void Q3Socket::connectionClosed()
+
+    This signal is emitted when the other end has closed the
+    connection. The read buffers may contain buffered input data which
+    you can read after the connection was closed.
+
+    \sa connectToHost(), close()
+*/
+
+
+/*!
+    \fn void Q3Socket::delayedCloseFinished()
+
+    This signal is emitted when a delayed close is finished.
+
+    If you call close() and there is buffered output data to be
+    written, Q3Socket goes into the Q3Socket::Closing state and
+    returns immediately. It will then keep writing to the socket until
+    all the data has been written. Then, the delayedCloseFinished()
+    signal is emitted.
+
+    \sa close()
+*/
+
+
+/*!
+    \fn void Q3Socket::readyRead()
+
+    This signal is emitted every time there is new incoming data.
+
+    Bear in mind that new incoming data is only reported once; if you do not
+    read all the data, this class buffers the data and you can read it later,
+    but no signal is emitted unless new data arrives. A good practice is to
+    read all data in the slot connected to this signal unless you are sure that
+    you need to receive more data to be able to process it.
+
+    \sa readBlock(), readLine(), bytesAvailable()
+*/
+
+
+/*!
+    \fn void Q3Socket::bytesWritten( int nbytes )
+
+    This signal is emitted when data has been written to the network.
+    The \a nbytes parameter specifies how many bytes were written.
+
+    The bytesToWrite() function is often used in the same context; it
+    indicates how many buffered bytes there are left to write.
+
+    \sa writeBlock(), bytesToWrite()
+*/
+
+
+/*!
+    Opens the socket using the specified QIODevice file mode \a m.
+    This function is called automatically when needed and you should
+    not call it yourself.
+
+    \sa close()
+*/
+
+bool Q3Socket::open( OpenMode m )
+{
+    if ( isOpen() ) {
+#if defined(QT_CHECK_STATE)
+	qWarning( "Q3Socket::open: Already open" );
+#endif
+	return false;
+    }
+    QIODevice::setOpenMode( m & ReadWrite );
+    return true;
+}
+
+/*!
+    \fn bool Q3Socket::open(int m)
+    \overload
+*/
+
+/*!
+    Closes the socket.
+
+    The read buffer is cleared.
+
+    If the output buffer is empty, the state is set to \c
+    Q3Socket::Idle and the connection is terminated immediately. If the
+    output buffer still contains data to be written, Q3Socket goes into
+    the Q3Socket::Closing state and the rest of the data will be
+    written. When all of the outgoing data have been written, the
+    state is set to Q3Socket::Idle and the connection is terminated.
+    At this point, the delayedCloseFinished() signal is emitted.
+
+    If you don't want that the data of the output buffer is written, call
+    clearPendingData() before you call close().
+
+    \sa state(), bytesToWrite() clearPendingData()
+*/
+
+void Q3Socket::close()
+{
+    if ( !isOpen() || d->state == Idle )	// already closed
+	return;
+    if ( d->state == Closing )
+	return;
+    if ( !d->rsn || !d->wsn )
+	return;
+#if defined(Q3SOCKET_DEBUG)
+    qDebug( "Q3Socket (%s): close socket", name() );
+#endif
+    if ( d->socket && d->wsize ) {		// there's data to be written
+	d->state = Closing;
+	if ( d->rsn )
+	    d->rsn->setEnabled( false );
+	if ( d->wsn )
+	    d->wsn->setEnabled( true );
+	d->rba.clear();				// clear incoming data
+	return;
+    }
+    resetStatus();
+    setOpenMode(NotOpen);
+    d->close();
+    d->state = Idle;
+}
+
+
+/*!
+    This function consumes \a nbytes bytes of data from the write
+    buffer.
+*/
+
+bool Q3Socket::consumeWriteBuf( Q_ULONG nbytes )
+{
+    if ( nbytes <= 0 || (qint64)nbytes > d->wsize )
+	return false;
+#if defined(Q3SOCKET_DEBUG)
+    qDebug( "Q3Socket (%s): skipWriteBuf %d bytes", name(), (int)nbytes );
+#endif
+    d->wsize -= nbytes;
+    for ( ;; ) {
+	QByteArray *a = d->wba.first();
+	if ( (qint64)(d->windex + nbytes) >= a->size() ) {
+	    nbytes -= a->size() - d->windex;
+	    d->wba.remove();
+	    d->windex = 0;
+	    if ( nbytes == 0 )
+		break;
+	} else {
+	    d->windex += nbytes;
+	    break;
+	}
+    }
+    return true;
+}
+
+
+
+/*!
+    Implementation of the abstract virtual QIODevice::flush() function.
+    This function always returns true.
+*/
+
+bool Q3Socket::flush()
+{
+    if ( !d->socket )
+        return true;
+    bool osBufferFull = false;
+    int consumed = 0;
+    while ( !osBufferFull && d->state >= Connecting && d->wsize > 0 ) {
+#if defined(Q3SOCKET_DEBUG)
+	qDebug( "Q3Socket (%s): flush: Write data to the socket", name() );
+#endif
+	QByteArray *a = d->wba.first();
+	int nwritten;
+	int i = 0;
+	if ( (int)a->size() - d->windex < 1460 ) {
+	    // Concatenate many smaller blocks.  the first may be
+	    // partial, but each subsequent block is copied entirely
+	    // or not at all.  the sizes here are picked so that we
+	    // generally won't trigger nagle's algorithm in the tcp
+	    // implementation: we concatenate if we'd otherwise send
+	    // less than PMTU bytes (we assume PMTU is 1460 bytes),
+	    // and concatenate up to the largest payload TCP/IP can
+	    // carry.  with these precautions, nagle's algorithm
+	    // should apply only when really appropriate.
+	    QByteArray out( 65536 );
+	    int j = d->windex;
+	    int s = a->size() - j;
+	    while ( a && i+s < (int)out.size() ) {
+		memcpy( out.data()+i, a->data()+j, s );
+		j = 0;
+		i += s;
+		a = d->wba.next();
+		s = a ? a->size() : 0;
+	    }
+	    nwritten = d->socket->write( out.data(), i );
+	    if ( d->wsn )
+		d->wsn->setEnabled( false ); // the QSocketNotifier documentation says so
+	} else {
+	    // Big block, write it immediately
+	    i = a->size() - d->windex;
+	    nwritten = d->socket->write( a->data() + d->windex, i );
+	    if ( d->wsn )
+		d->wsn->setEnabled( false ); // the QSocketNotifier documentation says so
+	}
+	if ( nwritten > 0 ) {
+	    if ( consumeWriteBuf( nwritten ) )
+		consumed += nwritten;
+	}
+	if ( nwritten < i )
+	    osBufferFull = true;
+    }
+    if ( consumed > 0 ) {
+#if defined(Q3SOCKET_DEBUG)
+	qDebug( "Q3Socket (%s): flush: wrote %d bytes, %d left",
+		name(), consumed, (int)d->wsize );
+#endif
+	emit bytesWritten( consumed );
+    }
+    if ( d->state == Closing && d->wsize == 0 ) {
+#if defined(Q3SOCKET_DEBUG)
+	qDebug( "Q3Socket (%s): flush: Delayed close done. Terminating.",
+		name() );
+#endif
+	resetStatus();
+	setOpenMode(NotOpen);
+	d->close();
+	d->state = Idle;
+	emit delayedCloseFinished();
+	return true;
+    }
+    if ( !d->socket->isOpen() ) {
+	d->connectionClosed();
+	emit connectionClosed();
+	return true;
+    }
+    if ( d->wsn )
+	d->wsn->setEnabled( d->wsize > 0 ); // write if there's data
+    return true;
+}
+
+
+/*!
+    Returns the number of incoming bytes that can be read right now
+    (like bytesAvailable()).
+*/
+
+QIODevice::Offset Q3Socket::size() const
+{
+    return (Offset)bytesAvailable();
+}
+
+
+/*!
+    Returns the current read index. Since Q3Socket is a sequential
+    device, the current read index is always zero.
+*/
+
+QIODevice::Offset Q3Socket::at() const
+{
+    return 0;
+}
+
+
+/*!
+    \overload
+
+    Moves the read index forward to \a index and returns true if the
+    operation was successful; otherwise returns false. Moving the
+    index forward means skipping incoming data.
+*/
+
+bool Q3Socket::at( Offset index )
+{
+    if ( index > d->rba.size() )
+	return false;
+    d->rba.consumeBytes( (Q_ULONG)index, 0 );			// throw away data 0..index-1
+    // After we read data from our internal buffer, if we use the
+    // setReadBufferSize() to limit our buffer, we might now be able to
+    // read more data in our buffer. So enable the read socket notifier,
+    // but do this only if we are not in a slot connected to the
+    // readyRead() signal since this might cause a bad recursive behavior.
+    // We can test for this condition by looking at the
+    // sn_read_alreadyCalled flag.
+    if ( d->rsn && Q3SocketPrivate::sn_read_alreadyCalled.findRef(this) == -1 )
+	d->rsn->setEnabled( true );
+    return true;
+}
+
+
+/*!
+    Returns true if there is no more data to read; otherwise returns false.
+*/
+
+bool Q3Socket::atEnd() const
+{
+    if ( d->socket == 0 )
+	return true;
+    Q3Socket * that = (Q3Socket *)this;
+    if ( that->d->socket->bytesAvailable() )	// a little slow, perhaps...
+	that->sn_read();
+    return that->d->rba.size() == 0;
+}
+
+
+/*!
+    Returns the number of incoming bytes that can be read, i.e. the
+    size of the input buffer. Equivalent to size().
+
+    \sa bytesToWrite()
+*/
+
+qint64 Q3Socket::bytesAvailable() const
+{
+    if ( d->socket == 0 )
+	return 0;
+    Q3Socket * that = (Q3Socket *)this;
+    if ( that->d->socket->bytesAvailable() ) // a little slow, perhaps...
+	(void)that->sn_read();
+    return that->d->rba.size() + QIODevice::bytesAvailable();
+}
+
+
+/*!
+    Wait up to \a msecs milliseconds for more data to be available.
+
+    If \a msecs is -1 the call will block indefinitely.
+
+    Returns the number of bytes available.
+
+    If \a timeout is non-null and no error occurred (i.e. it does not
+    return -1): this function sets *\a timeout to true, if the reason
+    for returning was that the timeout was reached; otherwise it sets
+    *\a timeout to false. This is useful to find out if the peer
+    closed the connection.
+
+    \warning This is a blocking call and should be avoided in event
+    driven applications.
+
+    \sa bytesAvailable()
+*/
+
+Q_ULONG Q3Socket::waitForMore( int msecs, bool *timeout ) const
+{
+    if ( d->socket == 0 )
+	return 0;
+    Q3Socket * that = (Q3Socket *)this;
+    if ( that->d->socket->waitForMore( msecs, timeout ) > 0 )
+	(void)that->sn_read( true );
+    return that->d->rba.size();
+}
+
+/*! \overload
+*/
+
+Q_ULONG Q3Socket::waitForMore( int msecs ) const
+{
+    return waitForMore( msecs, 0 );
+}
+
+/*!
+    Returns the number of bytes that are waiting to be written, i.e.
+    the size of the output buffer.
+
+    \sa bytesAvailable() clearPendingData()
+*/
+
+qint64 Q3Socket::bytesToWrite() const
+{
+    return d->wsize;
+}
+
+/*!
+    Deletes the data that is waiting to be written. This is useful if you want
+    to close the socket without waiting for all the data to be written.
+
+    \sa bytesToWrite() close() delayedCloseFinished()
+*/
+
+void Q3Socket::clearPendingData()
+{
+    d->wba.clear();
+    d->windex = d->wsize = 0;
+}
+
+/*!
+    Reads \a maxlen bytes from the socket into \a data and returns the
+    number of bytes read. Returns -1 if an error occurred.
+*/
+
+qint64 Q3Socket::readData( char *data, qint64 maxlen )
+{
+    if ( data == 0 && maxlen != 0 ) {
+#if defined(QT_CHECK_NULL)
+	qWarning( "Q3Socket::readBlock: Null pointer error" );
+#endif
+	return -1;
+    }
+    if ( !isOpen() ) {
+#if defined(QT_CHECK_STATE)
+	qWarning( "Q3Socket::readBlock: Socket is not open" );
+#endif
+	return -1;
+    }
+    if ( maxlen >= d->rba.size() )
+	maxlen = d->rba.size();
+#if defined(Q3SOCKET_DEBUG)
+    qDebug( "Q3Socket (%s): readBlock %d bytes", name(), (int)maxlen );
+#endif
+    d->rba.consumeBytes( maxlen, data );
+    // After we read data from our internal buffer, if we use the
+    // setReadBufferSize() to limit our buffer, we might now be able to
+    // read more data in our buffer. So enable the read socket notifier,
+    // but do this only if we are not in a slot connected to the
+    // readyRead() signal since this might cause a bad recursive behavior.
+    // We can test for this condition by looking at the
+    // sn_read_alreadyCalled flag.
+    if ( d->rsn && Q3SocketPrivate::sn_read_alreadyCalled.findRef(this) == -1 )
+	d->rsn->setEnabled( true );
+    return maxlen;
+}
+
+
+/*!
+    Writes \a len bytes to the socket from \a data and returns the
+    number of bytes written. Returns -1 if an error occurred.
+*/
+
+qint64 Q3Socket::writeData( const char *data, qint64 len )
+{
+#if defined(QT_CHECK_NULL)
+    if ( data == 0 && len != 0 ) {
+	qWarning( "Q3Socket::writeBlock: Null pointer error" );
+    }
+#endif
+#if defined(QT_CHECK_STATE)
+    if ( !isOpen() ) {
+	qWarning( "Q3Socket::writeBlock: Socket is not open" );
+	return -1;
+    }
+#endif
+#if defined(QT_CHECK_STATE)
+    if ( d->state == Closing ) {
+	qWarning( "Q3Socket::writeBlock: Cannot write, socket is closing" );
+    }
+#endif
+    if ( len == 0 || d->state == Closing || d->state == Idle )
+	return 0;
+    QByteArray *a = d->wba.last();
+
+    // next bit is sensitive.  if we're writing really small chunks,
+    // try to buffer up since system calls are expensive, and nagle's
+    // algorithm is even more expensive.  but if anything even
+    // remotely large is being written, try to issue a write at once.
+
+    bool writeNow = ( d->wsize + len >= 1400 || len > 512 );
+
+    if ( a && a->size() + len < 128 ) {
+	// small buffer, resize
+	int i = a->size();
+	a->resize( i+len );
+	memcpy( a->data()+i, data, len );
+    } else {
+	// append new buffer
+	a = new QByteArray( len );
+	memcpy( a->data(), data, len );
+	d->wba.append( a );
+    }
+    d->wsize += len;
+    if ( writeNow )
+	flush();
+    else if ( d->wsn )
+	d->wsn->setEnabled( true );
+#if defined(Q3SOCKET_DEBUG)
+    qDebug( "Q3Socket (%s): writeBlock %d bytes", name(), (int)len );
+#endif
+    return len;
+}
+
+
+/*!
+    Reads a single byte/character from the internal read buffer.
+    Returns the byte/character read, or -1 if there is nothing to be
+    read.
+
+    \sa bytesAvailable(), putch()
+*/
+
+int Q3Socket::getch()
+{
+    if ( isOpen() && d->rba.size() > 0 ) {
+	uchar c;
+	d->rba.consumeBytes( 1, (char*)&c );
+	// After we read data from our internal buffer, if we use the
+	// setReadBufferSize() to limit our buffer, we might now be able to
+	// read more data in our buffer. So enable the read socket notifier,
+	// but do this only if we are not in a slot connected to the
+	// readyRead() signal since this might cause a bad recursive behavior.
+	// We can test for this condition by looking at the
+	// sn_read_alreadyCalled flag.
+	if ( d->rsn && Q3SocketPrivate::sn_read_alreadyCalled.findRef(this) == -1 )
+	    d->rsn->setEnabled( true );
+	return c;
+    }
+    return -1;
+}
+
+
+/*!
+    Writes the character \a ch to the output buffer.
+
+    Returns \a ch, or -1 if an error occurred.
+
+    \sa getch()
+*/
+
+int Q3Socket::putch( int ch )
+{
+    char buf[2];
+    buf[0] = ch;
+    return writeBlock(buf, 1) == 1 ? ch : -1;
+}
+
+
+/*!
+    This implementation of the virtual function QIODevice::ungetch()
+    prepends the character \a ch to the read buffer so that the next
+    read returns this character as the first character of the output.
+*/
+
+int Q3Socket::ungetch( int ch )
+{
+#if defined(QT_CHECK_STATE)
+    if ( !isOpen() ) {
+	qWarning( "Q3Socket::ungetch: Socket not open" );
+	return -1;
+    }
+#endif
+    return d->rba.ungetch( ch );
+}
+
+
+/*!
+    Returns true if it's possible to read an entire line of text from
+    this socket at this time; otherwise returns false.
+
+    Note that if the peer closes the connection unexpectedly, this
+    function returns false. This means that loops such as this won't
+    work:
+
+    \snippet doc/src/snippets/code/src_qt3support_network_q3socket.cpp 0
+
+    \sa readLine()
+*/
+
+bool Q3Socket::canReadLine() const
+{
+    if ( ((Q3Socket*)this)->d->rba.scanNewline( 0 ) )
+	return true;
+    return ( bytesAvailable() > 0 &&
+	     (((Q3Socket*)this)->d->rba.scanNewline( 0 ) || QIODevice::canReadLine()) );
+}
+
+/*!
+  \internal
+    Internal slot for handling socket read notifications.
+
+    This function has can usually only be entered once (i.e. no
+    recursive calls). If the argument \a force is true, the function
+    is executed, but no readyRead() signals are emitted. This
+    behaviour is useful for the waitForMore() function, so that it is
+    possible to call waitForMore() in a slot connected to the
+    readyRead() signal.
+*/
+
+void Q3Socket::sn_read( bool force )
+{
+    Q_LONG maxToRead = 0;
+    if ( d->readBufferSize > 0 ) {
+	maxToRead = d->readBufferSize - d->rba.size();
+	if ( maxToRead <= 0 ) {
+	    if ( d->rsn )
+		d->rsn->setEnabled( false );
+	    return;
+	}
+    }
+
+    // Use Q3SocketPrivate::sn_read_alreadyCalled to avoid recursive calls of
+    // sn_read() (and as a result avoid emitting the readyRead() signal in a
+    // slot for readyRead(), if you use bytesAvailable()).
+    if ( !force && Q3SocketPrivate::sn_read_alreadyCalled.findRef(this) != -1 )
+	return;
+    Q3SocketPrivate::sn_read_alreadyCalled.append( this );
+
+    char buf[4096];
+    Q_LONG nbytes = d->socket->bytesAvailable();
+    Q_LONG nread;
+    QByteArray *a = 0;
+
+    if ( state() == Connecting ) {
+	if ( nbytes > 0 ) {
+	    tryConnection();
+	} else {
+	    // nothing to do, nothing to care about
+	    Q3SocketPrivate::sn_read_alreadyCalled.removeRef( this );
+	    return;
+	}
+    }
+    if ( state() == Idle ) {
+	Q3SocketPrivate::sn_read_alreadyCalled.removeRef( this );
+	return;
+    }
+
+    if ( nbytes <= 0 ) {			// connection closed?
+	// On Windows this may happen when the connection is still open.
+	// This happens when the system is heavily loaded and we have
+	// read all the data on the socket before a new WSAAsyncSelect
+	// event is processed. A new read operation would then block.
+	// This code is also useful when Q3Socket is used without an
+	// event loop.
+	nread = d->socket->readBlock( buf, maxToRead ? QMIN((Q_LONG)sizeof(buf),maxToRead) : sizeof(buf) );
+	if ( nread == 0 ) {			// really closed
+            if ( !d->socket->isOpen() ) {
+#if defined(Q3SOCKET_DEBUG)
+                qDebug( "Q3Socket (%s): sn_read: Connection closed", name() );
+#endif
+                d->connectionClosed();
+                emit connectionClosed();
+            }
+	    Q3SocketPrivate::sn_read_alreadyCalled.removeRef( this );
+	    return;
+	} else {
+	    if ( nread < 0 ) {
+		if ( d->socket->error() == Q3SocketDevice::NoError ) {
+		    // all is fine
+		    Q3SocketPrivate::sn_read_alreadyCalled.removeRef( this );
+		    return;
+		}
+#if defined(Q3SOCKET_DEBUG)
+		qWarning( "Q3Socket::sn_read (%s): Close error", name() );
+#endif
+		if ( d->rsn )
+		    d->rsn->setEnabled( false );
+		emit error( ErrSocketRead );
+		Q3SocketPrivate::sn_read_alreadyCalled.removeRef( this );
+		return;
+	    }
+	    a = new QByteArray( nread );
+	    memcpy( a->data(), buf, nread );
+	}
+
+    } else {					// data to be read
+#if defined(Q3SOCKET_DEBUG)
+	qDebug( "Q3Socket (%s): sn_read: %ld incoming bytes", name(), nbytes );
+#endif
+	if ( nbytes > (int)sizeof(buf) ) {
+	    // big
+	    a = new QByteArray( nbytes );
+	    nread = d->socket->readBlock( a->data(), maxToRead ? QMIN(nbytes,maxToRead) : nbytes );
+	} else {
+	    a = 0;
+	    nread = d->socket->readBlock( buf, maxToRead ? QMIN((Q_LONG)sizeof(buf),maxToRead) : sizeof(buf) );
+	    if ( nread > 0 ) {
+		// ##### could setRawData
+		a = new QByteArray( nread );
+		memcpy( a->data(), buf, nread );
+	    }
+	}
+	if ( nread == 0 ) {
+#if defined(Q3SOCKET_DEBUG)
+	    qDebug( "Q3Socket (%s): sn_read: Connection closed", name() );
+#endif
+	    // ### we should rather ask the socket device if it is closed
+	    d->connectionClosed();
+	    emit connectionClosed();
+	    Q3SocketPrivate::sn_read_alreadyCalled.removeRef( this );
+            delete a;
+	    return;
+	} else if ( nread < 0 ) {
+            delete a;
+
+	    if ( d->socket->error() == Q3SocketDevice::NoError ) {
+		// all is fine
+		Q3SocketPrivate::sn_read_alreadyCalled.removeRef( this );
+		return;
+	    }
+#if defined(QT_CHECK_RANGE)
+	    qWarning( "Q3Socket::sn_read: Read error" );
+#endif
+	    if ( d->rsn )
+		d->rsn->setEnabled( false );
+	    emit error( ErrSocketRead );
+	    Q3SocketPrivate::sn_read_alreadyCalled.removeRef( this );
+	    return;
+	}
+	if ( nread != (int)a->size() ) {		// unexpected
+#if defined(CHECK_RANGE) && !defined(Q_OS_WIN32)
+	    qWarning( "Q3Socket::sn_read: Unexpected short read" );
+#endif
+	    a->resize( nread );
+	}
+    }
+    d->rba.append( a );
+    if ( !force ) {
+	if ( d->rsn )
+	    d->rsn->setEnabled( false );
+	emit readyRead();
+	if ( d->rsn )
+	    d->rsn->setEnabled( true );
+    }
+
+    Q3SocketPrivate::sn_read_alreadyCalled.removeRef( this );
+}
+
+
+/*!
+  \internal
+    Internal slot for handling socket write notifications.
+*/
+
+void Q3Socket::sn_write()
+{
+    if ( d->state == Connecting )		// connection established?
+	tryConnection();
+    flush();
+}
+
+void Q3Socket::emitErrorConnectionRefused()
+{
+    emit error( ErrConnectionRefused );
+}
+
+void Q3Socket::tryConnection()
+{
+    if ( d->socket->connect( d->addr, d->port ) ) {
+	d->state = Connected;
+#if defined(Q3SOCKET_DEBUG)
+	qDebug( "Q3Socket (%s): sn_write: Got connection to %s",
+		name(), peerName().ascii() );
+#endif
+	if ( d->rsn )
+	    d->rsn->setEnabled( true );
+	emit connected();
+    } else {
+	d->state = Idle;
+	QTimer::singleShot( 0, this, SLOT(emitErrorConnectionRefused()) );
+	return;
+    }
+}
+
+
+/*!
+    Returns the socket number, or -1 if there is no socket at the moment.
+*/
+
+int Q3Socket::socket() const
+{
+    if ( d->socket == 0 )
+	return -1;
+    return d->socket->socket();
+}
+
+/*!
+    Sets the socket to use \a socket and the state() to \c Connected.
+    The socket must already be connected.
+
+    This allows us to use the Q3Socket class as a wrapper for other
+    socket types (e.g. Unix Domain Sockets).
+*/
+
+void Q3Socket::setSocket( int socket )
+{
+    setSocketIntern( socket );
+    d->state = Connection;
+    d->rsn->setEnabled( true );
+}
+
+
+/*!
+    Sets the socket to \a socket. This is used by both setSocket() and
+    connectToHost() and can also be used on unconnected sockets.
+*/
+
+void Q3Socket::setSocketIntern( int socket )
+{
+    if ( state() != Idle ) {
+	clearPendingData();
+        close();
+    }
+    Q_ULONG oldBufferSize = d ? d->readBufferSize : 0;
+    delete d;
+
+    d = new Q3SocketPrivate;
+    if (oldBufferSize)
+        d->readBufferSize = oldBufferSize;
+    if ( socket >= 0 ) {
+	Q3SocketDevice *sd = new Q3SocketDevice( socket, Q3SocketDevice::Stream );
+	sd->setBlocking( false );
+	sd->setAddressReusable( true );
+	d->setSocketDevice( this, sd );
+    }
+    d->state = Idle;
+
+    // Initialize the IO device flags
+    resetStatus();
+    open( IO_ReadWrite );
+
+    // hm... this is not very nice.
+    d->host.clear();
+    d->port = 0;
+#ifndef QT_NO_DNS
+    delete d->dns4;
+    d->dns4 = 0;
+    delete d->dns6;
+    d->dns6 = 0;
+#endif
+}
+
+
+/*!
+    Returns the host port number of this socket, in native byte order.
+*/
+
+Q_UINT16 Q3Socket::port() const
+{
+    if ( d->socket == 0 )
+	return 0;
+    return d->socket->port();
+}
+
+
+/*!
+    Returns the peer's host port number, normally as specified to the
+    connectToHost() function. If none has been set, this function
+    returns 0.
+
+    Note that Qt always uses native byte order, i.e. 67 is 67 in Qt;
+    there is no need to call htons().
+*/
+
+Q_UINT16 Q3Socket::peerPort() const
+{
+    if ( d->socket == 0 )
+	return 0;
+    return d->socket->peerPort();
+}
+
+
+/*!
+    Returns the host address of this socket. (This is normally the
+    main IP address of the host, but can be e.g. 127.0.0.1 for
+    connections to localhost.)
+*/
+
+QHostAddress Q3Socket::address() const
+{
+    if ( d->socket == 0 ) {
+	QHostAddress tmp;
+	return tmp;
+    }
+    return d->socket->address();
+}
+
+
+/*!
+    Returns the address of the connected peer if the socket is in
+    Connected state; otherwise an empty QHostAddress is returned.
+*/
+
+QHostAddress Q3Socket::peerAddress() const
+{
+    if ( d->socket == 0 ) {
+	QHostAddress tmp;
+	return tmp;
+    }
+    return d->socket->peerAddress();
+}
+
+
+/*!
+    Returns the host name as specified to the connectToHost()
+    function. An empty string is returned if none has been set.
+*/
+
+QString Q3Socket::peerName() const
+{
+    return d->host;
+}
+
+/*!
+    Sets the size of the Q3Socket's internal read buffer to \a bufSize.
+
+    Usually Q3Socket reads all data that is available from the operating
+    system's socket. If the buffer size is limited to a certain size, this
+    means that the Q3Socket class doesn't buffer more than this size of data.
+
+    If the size of the read buffer is 0, the read buffer is unlimited and all
+    incoming data is buffered. This is the default.
+
+    If you read the data in the readyRead() signal, you shouldn't use this
+    option since it might slow down your program unnecessary. This option is
+    useful if you only need to read the data at certain points in time, like in
+    a realtime streaming application.
+
+    \sa readBufferSize()
+*/
+
+void Q3Socket::setReadBufferSize( Q_ULONG bufSize )
+{
+    d->readBufferSize = bufSize;
+}
+
+/*!
+    Returns the size of the read buffer.
+
+    \sa setReadBufferSize()
+*/
+
+Q_ULONG Q3Socket::readBufferSize() const
+{
+    return d->readBufferSize;
+}
+
+/*!
+    \fn bool Q3Socket::isSequential() const
+    \internal
+*/
+
+QT_END_NAMESPACE
+
+#endif //QT_NO_NETWORK