/**************************************************************************** ** ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). ** All rights reserved. ** Contact: Nokia Corporation (qt-info@nokia.com) ** ** This file is part of the QtDeclarative 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 Technology Preview License Agreement accompanying ** this package. ** ** 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 1.1, included in the file LGPL_EXCEPTION.txt in this package. ** ** If you have questions regarding the use of this file, please contact ** Nokia at qt-info@nokia.com. ** ** ** ** ** ** ** ** ** $QT_END_LICENSE$ ** ****************************************************************************/ #include "private/qpacketprotocol_p.h" #include QT_BEGIN_NAMESPACE #define MAX_PACKET_SIZE 0x7FFFFFFF /*! \class QPacketProtocol \internal \brief The QPacketProtocol class encapsulates communicating discrete packets across fragmented IO channels, such as TCP sockets. QPacketProtocol makes it simple to send arbitrary sized data "packets" across fragmented transports such as TCP and UDP. As transmission boundaries are not respected, sending packets over protocols like TCP frequently involves "stitching" them back together at the receiver. QPacketProtocol makes this easier by performing this task for you. Packet data sent using QPacketProtocol is prepended with a 4-byte size header allowing the receiving QPacketProtocol to buffer the packet internally until it has all been received. QPacketProtocol does not perform any sanity checking on the size or on the data, so this class should only be used in prototyping or trusted situations where DOS attacks are unlikely. QPacketProtocol does not perform any communications itself. Instead it can operate on any QIODevice that supports the QIODevice::readyRead() signal. A logical "packet" is encapsulated by the companion QPacket class. The following example shows two ways to send data using QPacketProtocol. The transmitted data is equivalent in both. \code QTcpSocket socket; // ... connect socket ... QPacketProtocol protocol(&socket); // Send packet the quick way protocol.send() << "Hello world" << 123; // Send packet the longer way QPacket packet; packet << "Hello world" << 123; protocol.send(packet); \endcode Likewise, the following shows how to read data from QPacketProtocol, assuming that the QPacketProtocol::readyRead() signal has been emitted. \code // ... QPacketProtocol::readyRead() is emitted ... int a; QByteArray b; // Receive packet the quick way protocol.read() >> a >> b; // Receive packet the longer way QPacket packet = protocol.read(); p >> a >> b; \endcode \ingroup io \sa QPacket */ class QPacketProtocolPrivate : public QObject { Q_OBJECT public: QPacketProtocolPrivate(QPacketProtocol * parent, QIODevice * _dev) : QObject(parent), inProgressSize(-1), maxPacketSize(MAX_PACKET_SIZE), dev(_dev) { Q_ASSERT(4 == sizeof(qint32)); QObject::connect(this, SIGNAL(readyRead()), parent, SIGNAL(readyRead())); QObject::connect(this, SIGNAL(packetWritten()), parent, SIGNAL(packetWritten())); QObject::connect(this, SIGNAL(invalidPacket()), parent, SIGNAL(invalidPacket())); QObject::connect(dev, SIGNAL(readyRead()), this, SLOT(readyToRead()), Qt::QueuedConnection); QObject::connect(dev, SIGNAL(aboutToClose()), this, SLOT(aboutToClose())); QObject::connect(dev, SIGNAL(bytesWritten(qint64)), this, SLOT(bytesWritten(qint64))); } Q_SIGNALS: void readyRead(); void packetWritten(); void invalidPacket(); public Q_SLOTS: void aboutToClose() { inProgress.clear(); sendingPackets.clear(); inProgressSize = -1; } void bytesWritten(qint64 bytes) { Q_ASSERT(!sendingPackets.isEmpty()); while(bytes) { if(sendingPackets.at(0) > bytes) { sendingPackets[0] -= bytes; bytes = 0; } else { bytes -= sendingPackets.at(0); sendingPackets.removeFirst(); emit packetWritten(); } } } void readyToRead() { if(-1 == inProgressSize) { // We need a size header of sizeof(qint32) if(sizeof(qint32) > (uint)dev->bytesAvailable()) return; // Read size header int read = dev->read((char *)&inProgressSize, sizeof(qint32)); Q_ASSERT(read == sizeof(qint32)); Q_UNUSED(read); // Check sizing constraints if(inProgressSize > maxPacketSize) { QObject::disconnect(dev, SIGNAL(readyRead()), this, SLOT(readyToRead())); QObject::disconnect(dev, SIGNAL(aboutToClose()), this, SLOT(aboutToClose())); QObject::disconnect(dev, SIGNAL(bytesWritten(qint64)), this, SLOT(bytesWritten(qint64))); dev = 0; emit invalidPacket(); return; } inProgressSize -= sizeof(qint32); // Need to get trailing data readyToRead(); } else { inProgress.append(dev->read(inProgressSize - inProgress.size())); if(inProgressSize == inProgress.size()) { // Packet has arrived! packets.append(inProgress); inProgressSize = -1; inProgress.clear(); emit readyRead(); // Need to get trailing data readyToRead(); } } } public: QList sendingPackets; QList packets; QByteArray inProgress; qint32 inProgressSize; qint32 maxPacketSize; QIODevice * dev; }; /*! Construct a QPacketProtocol instance that works on \a dev with the specified \a parent. */ QPacketProtocol::QPacketProtocol(QIODevice * dev, QObject * parent) : QObject(parent), d(new QPacketProtocolPrivate(this, dev)) { Q_ASSERT(dev); } /*! Destroys the QPacketProtocol instance. */ QPacketProtocol::~QPacketProtocol() { } /*! Returns the maximum packet size allowed. By default this is 2,147,483,647 bytes. If a packet claiming to be larger than the maximum packet size is received, the QPacketProtocol::invalidPacket() signal is emitted. \sa QPacketProtocol::setMaximumPacketSize() */ qint32 QPacketProtocol::maximumPacketSize() const { return d->maxPacketSize; } /*! Sets the maximum allowable packet size to \a max. \sa QPacketProtocol::maximumPacketSize() */ qint32 QPacketProtocol::setMaximumPacketSize(qint32 max) { if(max > (signed)sizeof(qint32)) d->maxPacketSize = max; return d->maxPacketSize; } /*! Returns a streamable object that is transmitted on destruction. For example \code protocol.send() << "Hello world" << 123; \endcode will send a packet containing "Hello world" and 123. To construct more complex packets, explicitly construct a QPacket instance. */ QPacketAutoSend QPacketProtocol::send() { return QPacketAutoSend(this); } /*! \fn void QPacketProtocol::send(const QPacket & packet) Transmit the \a packet. */ void QPacketProtocol::send(const QPacket & p) { if(p.b.isEmpty()) return; // We don't send empty packets qint64 sendSize = p.b.size() + sizeof(qint32); d->sendingPackets.append(sendSize); qint32 sendSize32 = sendSize; qint64 writeBytes = d->dev->write((char *)&sendSize32, sizeof(qint32)); Q_ASSERT(writeBytes == sizeof(qint32)); writeBytes = d->dev->write(p.b); Q_ASSERT(writeBytes == p.b.size()); } /*! Returns the number of received packets yet to be read. */ qint64 QPacketProtocol::packetsAvailable() const { return d->packets.count(); } /*! Discard any unread packets. */ void QPacketProtocol::clear() { d->packets.clear(); } /*! Return the next unread packet, or an invalid QPacket instance if no packets are available. This method does NOT block. */ QPacket QPacketProtocol::read() { if(0 == d->packets.count()) return QPacket(); QPacket rv(d->packets.at(0)); d->packets.removeFirst(); return rv; } /*! Return the QIODevice passed to the QPacketProtocol constructor. */ QIODevice * QPacketProtocol::device() { return d->dev; } /*! \fn void QPacketProtocol::readyRead() Emitted whenever a new packet is received. Applications may use QPacketProtocol::read() to retrieve this packet. */ /*! \fn void QPacketProtocol::invalidPacket() A packet larger than the maximum allowable packet size was received. The packet will be discarded and, as it indicates corruption in the protocol, no further packets will be received. */ /*! \fn void QPacketProtocol::packetWritten() Emitted each time a packet is completing written to the device. This signal may be used for communications flow control. */ /*! \class QPacket \internal \brief The QPacket class encapsulates an unfragmentable packet of data to be transmitted by QPacketProtocol. The QPacket class works together with QPacketProtocol to make it simple to send arbitrary sized data "packets" across fragmented transports such as TCP and UDP. QPacket provides a QDataStream interface to an unfragmentable packet. Applications should construct a QPacket, propagate it with data and then transmit it over a QPacketProtocol instance. For example: \code QPacketProtocol protocol(...); QPacket myPacket; myPacket << "Hello world!" << 123; protocol.send(myPacket); \endcode As long as both ends of the connection are using the QPacketProtocol class, the data within this packet will be delivered unfragmented at the other end, ready for extraction. \code QByteArray greeting; int count; QPacket myPacket = protocol.read(); myPacket >> greeting >> count; \endcode Only packets returned from QPacketProtocol::read() may be read from. QPacket instances constructed by directly by applications are for transmission only and are considered "write only". Attempting to read data from them will result in undefined behavior. \ingroup io \sa QPacketProtocol */ /*! Constructs an empty write-only packet. */ QPacket::QPacket() : QDataStream(), buf(0) { buf = new QBuffer(&b); buf->open(QIODevice::WriteOnly); setDevice(buf); } /*! Destroys the QPacket instance. */ QPacket::~QPacket() { if(buf) { delete buf; buf = 0; } } /*! Creates a copy of \a other. The initial stream positions are shared, but the two packets are otherwise independent. */ QPacket::QPacket(const QPacket & other) : QDataStream(), b(other.b), buf(0) { buf = new QBuffer(&b); buf->open(other.buf->openMode()); setDevice(buf); } /*! \internal */ QPacket::QPacket(const QByteArray & ba) : QDataStream(), b(ba), buf(0) { buf = new QBuffer(&b); buf->open(QIODevice::ReadOnly); setDevice(buf); } /*! Returns true if this packet is empty - that is, contains no data. */ bool QPacket::isEmpty() const { return b.isEmpty(); } /*! Clears data in the packet. This is useful for reusing one writable packet. For example \code QPacketProtocol protocol(...); QPacket packet; packet << "Hello world!" << 123; protocol.send(packet); packet.clear(); packet << "Goodbyte world!" << 789; protocol.send(packet); \endcode */ void QPacket::clear() { QBuffer::OpenMode oldMode = buf->openMode(); buf->close(); b.clear(); buf->setBuffer(&b); // reset QBuffer internals with new size of b. buf->open(oldMode); } /*! \class QPacketAutoSend \internal \internal */ QPacketAutoSend::QPacketAutoSend(QPacketProtocol * _p) : QPacket(), p(_p) { } QPacketAutoSend::~QPacketAutoSend() { if(!b.isEmpty()) p->send(*this); } QT_END_NAMESPACE #include