The QPacketProtocol class encapsulates communicating discrete packets across fragmented IO channels, such as TCP sockets. More...

#include <qpacketprotocol_p.h>

Inheritance diagram for QPacketProtocol:

Collaboration diagram for QPacketProtocol:

Signals
void	readyRead ()
	Emitted whenever a new packet is received.

void	error ()

Signals inherited from QObject
void	destroyed (QObject *=nullptr)
	This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.

void	objectNameChanged (const QString &objectName, QPrivateSignal)
	This signal is emitted after the object's name has been changed.

Public Member Functions
	QPacketProtocol (QIODevice dev, QObject parent=nullptr)
	Construct a QPacketProtocol instance that works on dev with the specified parent.

void	send (const QByteArray &data)
	Transmit the packet.

qint64	packetsAvailable () const
	Returns the number of received packets yet to be read.

QByteArray	read ()
	Return the next unread packet, or an empty QByteArray if no packets are available.

bool	waitForReadyRead (int msecs=3000)
	This function locks until a new packet is available for reading and the \l{QIODevice::}{readyRead()} signal has been emitted.

Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)
	Constructs an object with parent object parent.

virtual	~QObject ()
	Destroys the object, deleting all its child objects.

virtual bool	event (QEvent *event)
	This virtual function receives events to an object and should return true if the event e was recognized and processed.

virtual bool	eventFilter (QObject watched, QEvent event)
	Filters events if this object has been installed as an event filter for the watched object.

QString	objectName () const

Q_WEAK_OVERLOAD void	setObjectName (const QString &name)
	Sets the object's name to name.

void	setObjectName (QAnyStringView name)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

QBindable< QString >	bindableObjectName ()

bool	isWidgetType () const
	Returns `true` if the object is a widget; otherwise returns `false`.

bool	isWindowType () const
	Returns `true` if the object is a window; otherwise returns `false`.

bool	isQuickItemType () const
	Returns `true` if the object is a QQuickItem; otherwise returns `false`.

bool	signalsBlocked () const noexcept
	Returns `true` if signals are blocked; otherwise returns `false`.

bool	blockSignals (bool b) noexcept
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).

QThread *	thread () const
	Returns the thread in which the object lives.

bool	moveToThread (QThread *thread QT6_DECL_NEW_OVERLOAD_TAIL)
	Changes the thread affinity for this object and its children and returns `true` on success.

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
	This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.

int	startTimer (std::chrono::nanoseconds time, Qt::TimerType timerType=Qt::CoarseTimer)

void	killTimer (int id)
	Kills the timer with timer identifier, id.

void	killTimer (Qt::TimerId id)

template<typename T >
T	findChild (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.

template<typename T >
QList< T >	findChildren (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.

template<typename T >
T	findChild (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

const QObjectList &	children () const
	Returns a list of child objects.

void	setParent (QObject *parent)
	Makes the object a child of parent.

void	installEventFilter (QObject *filterObj)
	Installs an event filter filterObj on this object.

void	removeEventFilter (QObject *obj)
	Removes an event filter object obj from this object.

QMetaObject::Connection	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const

bool	disconnect (const char signal=nullptr, const QObject receiver=nullptr, const char *member=nullptr) const

bool	disconnect (const QObject receiver, const char member=nullptr) const

void	dumpObjectTree () const
	Dumps a tree of children to the debug output.

void	dumpObjectInfo () const
	Dumps information about signal connections, etc.

bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value.

bool	setProperty (const char *name, QVariant &&value)

QVariant	property (const char *name) const
	Returns the value of the object's name property.

QList< QByteArray >	dynamicPropertyNames () const

QBindingStorage *	bindingStorage ()

const QBindingStorage *	bindingStorage () const

QObject *	parent () const
	Returns a pointer to the parent object.

bool	inherits (const char *classname) const
	Returns `true` if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns `false`.

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe

Static Public Member Functions inherited from QObject
static QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	\threadsafe

static QMetaObject::Connection	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	\threadsafe

static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)

static bool	disconnect (const QMetaObject::Connection &)
	Disconnect a connection.

template<typename Func1 , typename Func2 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object receiver, Func2 slot)

template<typename Func1 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject receiver, void **zero)

Protected Member Functions inherited from QObject
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.

int	senderSignalIndex () const

int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal.

bool	isSignalConnected (const QMetaMethod &signal) const

virtual void	timerEvent (QTimerEvent *event)
	This event handler can be reimplemented in a subclass to receive timer events for the object.

virtual void	childEvent (QChildEvent *event)
	This event handler can be reimplemented in a subclass to receive child events.

virtual void	customEvent (QEvent *event)
	This event handler can be reimplemented in a subclass to receive custom events.

virtual void	connectNotify (const QMetaMethod &signal)

virtual void	disconnectNotify (const QMetaMethod &signal)

	QObject (QObjectPrivate &dd, QObject *parent=nullptr)

Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Properties inherited from QObject
QString	objectName
	the name of this object

Related Symbols inherited from QObject
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.

template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()

	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Detailed Description

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 simply a QByteArray. The following example how to send data using QPacketProtocol.

QTcpSocket socket;
// ... connect socket ...
 
QPacketProtocol protocol(&socket);
 
// Send a packet
QDataStream packet;
packet << "Hello world" << 123;
protocol.send(packet.data());

Likewise, the following shows how to read data from QPacketProtocol, assuming that the QPacketProtocol::readyRead() signal has been emitted.

// ... QPacketProtocol::readyRead() is emitted ...
 
int a;
QByteArray b;
 
// Receive packet
QDataStream packet(protocol.read());
p >> a >> b;

Definition at line 25 of file qpacketprotocol_p.h.

Constructor & Destructor Documentation

◆ QPacketProtocol()

QPacketProtocol::QPacketProtocol	(	QIODevice *	dev,
		QObject *	parent = nullptr )

explicit

Construct a QPacketProtocol instance that works on dev with the specified parent.

Definition at line 88 of file qpacketprotocol.cpp.

References QIODevice::bytesWritten(), QObject::connect(), Q_ASSERT, and QIODevice::readyRead().

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Member Function Documentation

◆ error

void QPacketProtocol::error ( )

signal

Referenced by send(), and QQmlDebugServerImpl::setDevice().

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◆ packetsAvailable()

qint64 QPacketProtocol::packetsAvailable ( ) const

Returns the number of received packets yet to be read.

Definition at line 129 of file qpacketprotocol.cpp.

References d.

◆ read()

QByteArray QPacketProtocol::read ( )

Return the next unread packet, or an empty QByteArray if no packets are available.

This method does NOT block.

Definition at line 139 of file qpacketprotocol.cpp.

References d, and QByteArray().

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◆ readyRead

void QPacketProtocol::readyRead ( )

signal

Emitted whenever a new packet is received.

Applications may use QPacketProtocol::read() to retrieve this packet.

Referenced by QQmlDebugConnectionPrivate::createProtocol(), and QQmlDebugServerImpl::setDevice().

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◆ send()

void QPacketProtocol::send ( const QByteArray & data )

Transmit the packet.

Definition at line 103 of file qpacketprotocol.cpp.

References d, emit, error(), and qToLittleEndian().

Referenced by QQmlDebugConnectionPrivate::advertisePlugins().

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◆ waitForReadyRead()

bool QPacketProtocol::waitForReadyRead ( int msecs = 3000 )

This function locks until a new packet is available for reading and the \l{QIODevice::}{readyRead()} signal has been emitted.

The function will timeout after msecs milliseconds; the default timeout is 30000 milliseconds.

The function returns true if the readyRead() signal is emitted and there is new data available for reading; otherwise it returns false (if an error occurred or the operation timed out).

Definition at line 156 of file qpacketprotocol.cpp.

References d, qt_subtract_from_timeout(), and QElapsedTimer::start().

Referenced by QQmlDebugServerImpl::setDevice().

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The documentation for this class was generated from the following files: