PySide6.QtNetwork.QTcpServer

class QTcpServer

The QTcpServer class provides a TCP-based server. More…

Inheritance diagram of PySide6.QtNetwork.QTcpServer

Inherited by: QSslServer

Synopsis

Methods

Virtual methods

Signals

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description

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 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.

See also

QTcpSocket Fortune Server Threaded Fortune Server Torrent Example

__init__([parent=None])
Parameters:

parent – QObject

Constructs a QTcpServer object.

parent is passed to the QObject constructor.

acceptError(socketError)
Parameters:

socketError – SocketError

This signal is emitted when accepting a new connection results in an error. The socketError parameter describes the type of error that occurred.

addPendingConnection(socket)
Parameters:

socket – QTcpSocket

This function is called by incomingConnection() to add the 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.

See also

incomingConnection() pendingConnectionAvailable()

close()

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

See also

listen()

errorString()
Return type:

str

Returns a human readable description of the last error that occurred.

See also

serverError()

hasPendingConnections()
Return type:

bool

Returns true if the server has a pending connection; otherwise returns false.

incomingConnection(handle)
Parameters:

handle – qintptr

This virtual function is called by QTcpServer when a new connection is available. The 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 socketDescriptor may not be usable with native socket functions, and should only be used with 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.

See also

newConnection() nextPendingConnection() addPendingConnection()

isListening()
Return type:

bool

Returns true if the server is currently listening for incoming connections; otherwise returns false.

See also

listen()

listen([address=QHostAddress.Any[, port=0]])
Parameters:
Return type:

bool

Tells the server to listen for incoming connections on address address and port port. If port is 0, a port is chosen automatically. If address is Any , the server will listen on all network interfaces.

Returns true on success; otherwise returns false.

See also

isListening()

listenBacklogSize()
Return type:

int

Returns the backlog queue size of to be accepted connections.

maxPendingConnections()
Return type:

int

Returns the maximum number of pending accepted connections. The default is 30.

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.

nextPendingConnection()
Return type:

QTcpSocket

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.

None 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() .

See also

hasPendingConnections()

pauseAccepting()

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

pendingConnectionAvailable()

This signal is emitted every time a new connection has been added to the pending connections queue.

proxy()
Return type:

QNetworkProxy

Returns the network proxy for this socket. By default DefaultProxy is used.

resumeAccepting()

Resumes accepting new connections.

See also

pauseAccepting()

serverAddress()
Return type:

QHostAddress

Returns the server’s address if the server is listening for connections; otherwise returns Null .

serverError()
Return type:

SocketError

Returns an error code for the last error that occurred.

See also

errorString()

serverPort()
Return type:

int

Returns the server’s port if the server is listening for connections; otherwise returns 0.

setListenBacklogSize(size)
Parameters:

size – int

Sets the backlog queue size of to be accepted connections to 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() .

See also

listenBacklogSize()

setMaxPendingConnections(numConnections)
Parameters:

numConnections – int

Sets the maximum number of pending accepted connections to numConnections. QTcpServer will accept no more than 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.

setProxy(networkProxy)
Parameters:

networkProxy – QNetworkProxy

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Sets the explicit network proxy for this socket to networkProxy.

To disable the use of a proxy for this socket, use the NoProxy proxy type:

server.setProxy(QNetworkProxy.NoProxy)

See also

proxy() QNetworkProxy

setSocketDescriptor(socketDescriptor)
Parameters:

socketDescriptor – qintptr

Return type:

bool

Sets the socket descriptor this server should use when listening for incoming connections to socketDescriptor. Returns true if the socket is set successfully; otherwise returns false.

The socket is assumed to be in listening state.

socketDescriptor()
Return type:

qintptr

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.

waitForNewConnection(msec)
Parameters:

msec – int

Return type:

(retval, timedOut)

Waits for at most 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 timedOut is not None, *``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.