QWebSocket#
Implements a TCP socket that talks the WebSocket protocol. More…
Synopsis#
Functions#
def
abort
()def
bytesToWrite
()def
closeCode
()def
closeReason
()def
continueInterruptedHandshake
()def
error
()def
errorString
()def
flush
()def
handshakeOptions
()def
ignoreSslErrors
(errors)def
isValid
()def
localAddress
()def
localPort
()def
maskGenerator
()def
maxAllowedIncomingFrameSize
()def
origin
()def
outgoingFrameSize
()def
pauseMode
()def
peerAddress
()def
peerName
()def
peerPort
()def
proxy
()def
readBufferSize
()def
request
()def
requestUrl
()def
resourceName
()def
resume
()def
sendBinaryMessage
(data)def
sendTextMessage
(message)def
setMaskGenerator
(maskGenerator)def
setMaxAllowedIncomingFrameSize
(maxAllowedIncomingFrameSize)def
setMaxAllowedIncomingMessageSize
(maxAllowedIncomingMessageSize)def
setOutgoingFrameSize
(outgoingFrameSize)def
setPauseMode
(pauseMode)def
setProxy
(networkProxy)def
setReadBufferSize
(size)def
setSslConfiguration
(sslConfiguration)def
sslConfiguration
()def
state
()def
subprotocol
()def
version
()
Slots#
Signals#
def
aboutToClose
()def
alertReceived
(level, type, description)def
alertSent
(level, type, description)def
binaryFrameReceived
(frame, isLastFrame)def
binaryMessageReceived
(message)def
bytesWritten
(bytes)def
connected
()def
disconnected
()def
error
(error)def
errorOccurred
(error)def
handshakeInterruptedOnError
(error)def
peerVerifyError
(error)def
pong
(elapsedTime, payload)def
preSharedKeyAuthenticationRequired
(authenticator)def
proxyAuthenticationRequired
(proxy, pAuthenticator)def
readChannelFinished
()def
sslErrors
(errors)def
stateChanged
(state)def
textFrameReceived
(frame, isLastFrame)def
textMessageReceived
(message)
Static functions#
def
maxIncomingFrameSize
()def
maxIncomingMessageSize
()def
maxOutgoingFrameSize
()
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#
WebSockets is a web technology providing full-duplex communications channels over a single TCP connection. The WebSocket protocol was standardized by the IETF as RFC 6455 in 2011. QWebSocket
can both be used in a client application and server application.
This class was modeled after QAbstractSocket
.
QWebSocket
currently does not support WebSocket Extensions .
QWebSocket
only supports version 13 of the WebSocket protocol, as outlined in RFC 6455 .
Note
Some proxies do not understand certain HTTP headers used during a WebSocket handshake. In that case, non-secure WebSocket connections fail. The best way to mitigate against this problem is to use WebSocket over a secure connection.
Warning
To generate masks, this implementation of WebSockets uses the reasonably secure global()
->generate() function. For more information about the importance of good masking, see “Talking to Yourself for Fun and Profit” by Lin-Shung Huang et al . The best measure against attacks mentioned in the document above, is to use QWebSocket
over a secure connection (wss://). In general, always be careful to not have 3rd party script access to a QWebSocket
in your application.
See also
QAbstractSocket
QTcpSocket
QWebSocket client example
- class PySide6.QtWebSockets.QWebSocket([origin=""[, version=QWebSocketProtocol.VersionLatest[, parent=None]]])#
- Parameters:
origin – str
version –
Version
parent –
PySide6.QtCore.QObject
Creates a new QWebSocket
with the given origin
, the version
of the protocol to use and parent
.
The origin
of the client is as specified in RFC 6454 . (The origin
is not required for non-web browser clients (see RFC 6455 )). The origin
may not contain new line characters, otherwise the connection will be aborted immediately during the handshake phase.
Note
Currently only V13 ( RFC 6455 ) is supported
- PySide6.QtWebSockets.QWebSocket.abort()#
Aborts the current socket and resets the socket. Unlike close()
, this function immediately closes the socket, discarding any pending data in the write buffer.
- PySide6.QtWebSockets.QWebSocket.aboutToClose()#
This signal is emitted when the socket is about to close. Connect this signal if you have operations that need to be performed before the socket closes (e.g., if you have data in a separate buffer that needs to be written to the device).
See also
- PySide6.QtWebSockets.QWebSocket.alertReceived(level, type, description)#
- Parameters:
level –
AlertLevel
type –
AlertType
description – str
QWebSocket
emits this signal if an alert message was received from a peer. level
tells if the alert was fatal or it was a warning. type
is the code explaining why the alert was sent. When a textual description of the alert message is available, it is supplied in description
.
Note
The signal is mostly for informational and debugging purposes and does not require any handling in the application. If the alert was fatal, underlying backend will handle it and close the connection.
- PySide6.QtWebSockets.QWebSocket.alertSent(level, type, description)#
- Parameters:
level –
AlertLevel
type –
AlertType
description – str
QWebSocket
emits this signal if an alert message was sent to a peer. level
describes if it was a warning or a fatal error. type
gives the code of the alert message. When a textual description of the alert message is available, it is supplied in description
.
Note
This signal is mostly informational and can be used for debugging purposes, normally it does not require any actions from the application.
- PySide6.QtWebSockets.QWebSocket.binaryFrameReceived(frame, isLastFrame)#
- Parameters:
frame –
PySide6.QtCore.QByteArray
isLastFrame – bool
This signal is emitted whenever a binary frame is received. The frame
contains the data and isLastFrame
indicates whether this is the last frame of the complete message.
This signal can be used to process large messages frame by frame, instead of waiting for the complete message to arrive.
See also
- PySide6.QtWebSockets.QWebSocket.binaryMessageReceived(message)#
- Parameters:
message –
PySide6.QtCore.QByteArray
This signal is emitted whenever a binary message is received. The message
contains the received bytes.
See also
- PySide6.QtWebSockets.QWebSocket.bytesToWrite()#
- Return type:
int
Returns the number of bytes that are waiting to be written. The bytes are written when control goes back to the event loop or when flush()
is called.
See also
- PySide6.QtWebSockets.QWebSocket.bytesWritten(bytes)#
- Parameters:
bytes – int
This signal is emitted every time a payload of data has been written to the socket. The bytes
argument is set to the number of bytes that were written in this payload.
Note
This signal has the same meaning both for secure and non-secure WebSockets. As opposed to QSslSocket
, bytesWritten() is only emitted when encrypted data is effectively written (see encryptedBytesWritten()
).
See also
- PySide6.QtWebSockets.QWebSocket.close([closeCode=QWebSocketProtocol.CloseCodeNormal[, reason=""]])#
- Parameters:
closeCode –
CloseCode
reason – str
Gracefully closes the socket with the given closeCode
and reason
.
Any data in the write buffer is flushed before the socket is closed. The closeCode
is a CloseCode
indicating the reason to close, and reason
describes the reason of the closure more in detail. All control frames, including the Close frame, are limited to 125 bytes. Since two of these are used for closeCode
the maximum length of reason
is 123! If reason
exceeds this limit it will be truncated.
Returns the code indicating why the socket was closed.
See also
CloseCode
closeReason()
- PySide6.QtWebSockets.QWebSocket.closeReason()#
- Return type:
str
Returns the reason why the socket was closed.
See also
- PySide6.QtWebSockets.QWebSocket.connected()#
Emitted when a connection is successfully established. A connection is successfully established when the socket is connected and the handshake was successful.
See also
- PySide6.QtWebSockets.QWebSocket.continueInterruptedHandshake()#
If an application wants to conclude a handshake even after receiving handshakeInterruptedOnError()
signal, it must call this function. This call must be done from a slot function attached to the signal. The signal-slot connection must be direct.
See also
handshakeInterruptedOnError()
setHandshakeMustInterruptOnError()
- PySide6.QtWebSockets.QWebSocket.disconnected()#
Emitted when the socket is disconnected.
See also
- PySide6.QtWebSockets.QWebSocket.error()#
- Return type:
Returns the type of error that last occurred
See also
- PySide6.QtWebSockets.QWebSocket.error(error)
- Parameters:
error –
SocketError
Note
This function is deprecated.
Use errorOccurred
( SocketError
error) instead.
- PySide6.QtWebSockets.QWebSocket.errorOccurred(error)#
- Parameters:
error –
SocketError
This signal is emitted after an error occurred.
The error
parameter describes the type of error that occurred.
SocketError
is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE()
and qRegisterMetaType()
.
See also
- PySide6.QtWebSockets.QWebSocket.errorString()#
- Return type:
str
Returns a human-readable description of the last error that occurred
See also
- PySide6.QtWebSockets.QWebSocket.flush()#
- Return type:
bool
This function writes as much as possible from the internal write buffer to the underlying network socket, without blocking. If any data was written, this function returns true; otherwise false is returned. Call this function if you need QWebSocket
to start sending buffered data immediately. The number of bytes successfully written depends on the operating system. In most cases, you do not need to call this function, because QWebSocket
will start sending data automatically once control goes back to the event loop.
- PySide6.QtWebSockets.QWebSocket.handshakeInterruptedOnError(error)#
- Parameters:
error –
PySide6.QtNetwork.QSslError
QWebSocket
emits this signal if a certificate verification error was found and if early error reporting was enabled in QSslConfiguration
. An application is expected to inspect the error
and decide if it wants to continue the handshake, or abort it and send an alert message to the peer. The signal-slot connection must be direct.
See also
continueInterruptedHandshake()
sslErrors()
setHandshakeMustInterruptOnError()
- PySide6.QtWebSockets.QWebSocket.handshakeOptions()#
- Return type:
Returns the handshake options that were used to open this socket.
- PySide6.QtWebSockets.QWebSocket.ignoreSslErrors()#
This slot tells QWebSocket
to ignore errors during QWebSocket
‘s handshake phase and continue connecting. If you want to continue with the connection even if errors occur during the handshake phase, then you must call this slot, either from a slot connected to sslErrors()
, or before the handshake phase. If you don’t call this slot, either in response to errors or before the handshake, the connection will be dropped after the sslErrors()
signal has been emitted.
Warning
Be sure to always let the user inspect the errors reported by the sslErrors()
signal, and only call this method upon confirmation from the user that proceeding is ok. If there are unexpected errors, the connection should be aborted. Calling this method without inspecting the actual errors will most likely pose a security risk for your application. Use it with great care!
See also
sslErrors()
ignoreSslErrors()
ignoreSslErrors()
- PySide6.QtWebSockets.QWebSocket.ignoreSslErrors(errors)
- Parameters:
errors –
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
This is an overloaded function.
This method tells QWebSocket
to ignore the errors given in errors
.
Note that you can set the expected certificate in the SSL error: If, for instance, you want to connect to a server that uses a self-signed certificate, consider the following snippet:
cert = QSslCertificate.fromPath("server-certificate.pem") error = QSslError(QSslError.SelfSignedCertificate, cert.at(0)) expectedSslErrors = QList() expectedSslErrors.append(error) socket = QWebSocket() socket.ignoreSslErrors(expectedSslErrors) socket.open(QUrl("wss://myserver.at.home"))
Multiple calls to this function will replace the list of errors that were passed in previous calls. You can clear the list of errors you want to ignore by calling this function with an empty list.
See also
- PySide6.QtWebSockets.QWebSocket.isValid()#
- Return type:
bool
Returns true
if the socket is ready for reading and writing; otherwise returns false
.
- PySide6.QtWebSockets.QWebSocket.localAddress()#
- Return type:
Returns the local address
- PySide6.QtWebSockets.QWebSocket.localPort()#
- Return type:
quint16
Returns the local port
- PySide6.QtWebSockets.QWebSocket.maskGenerator()#
- Return type:
Returns the mask generator that is currently used by this QWebSocket
.
See also
- PySide6.QtWebSockets.QWebSocket.maxAllowedIncomingFrameSize()#
- Return type:
int
Returns the maximum allowed size of an incoming websocket frame.
See also
- PySide6.QtWebSockets.QWebSocket.maxAllowedIncomingMessageSize()#
- Return type:
int
Returns the maximum allowed size of an incoming websocket message.
See also
- static PySide6.QtWebSockets.QWebSocket.maxIncomingFrameSize()#
- Return type:
int
Returns the maximum supported size of an incoming websocket frame for this websocket implementation.
- static PySide6.QtWebSockets.QWebSocket.maxIncomingMessageSize()#
- Return type:
int
Returns the maximum supported size of an incoming websocket message for this websocket implementation.
- static PySide6.QtWebSockets.QWebSocket.maxOutgoingFrameSize()#
- Return type:
int
Returns the maximum supported size of an outgoing websocket frame for this websocket implementation.
- PySide6.QtWebSockets.QWebSocket.open(request)#
- Parameters:
request –
PySide6.QtNetwork.QNetworkRequest
Opens a WebSocket connection using the given request
.
The request
url will be used to open the WebSocket connection. Headers present in the request will be sent to the server in the upgrade request, together with the ones needed for the websocket handshake.
- PySide6.QtWebSockets.QWebSocket.open(request, options)
- Parameters:
request –
PySide6.QtNetwork.QNetworkRequest
Opens a WebSocket connection using the given request
and options
.
The request
url will be used to open the WebSocket connection. Headers present in the request will be sent to the server in the upgrade request, together with the ones needed for the websocket handshake.
Additional options for the WebSocket handshake such as subprotocols can be specified in options
.
- PySide6.QtWebSockets.QWebSocket.open(url)
- Parameters:
url –
PySide6.QtCore.QUrl
Opens a WebSocket connection using the given url
.
If the url contains newline characters (\r\n), then the error signal will be emitted with ConnectionRefusedError
as error type.
- PySide6.QtWebSockets.QWebSocket.open(url, options)
- Parameters:
url –
PySide6.QtCore.QUrl
Opens a WebSocket connection using the given url
and options
.
If the url contains newline characters (\r\n), then the error signal will be emitted with ConnectionRefusedError
as error type.
Additional options for the WebSocket handshake such as subprotocols can be specified in options
.
- PySide6.QtWebSockets.QWebSocket.origin()#
- Return type:
str
Returns the current origin.
- PySide6.QtWebSockets.QWebSocket.outgoingFrameSize()#
- Return type:
int
Returns the maximum size of an outgoing websocket frame.
See also
- PySide6.QtWebSockets.QWebSocket.pauseMode()#
- Return type:
PauseModes
Returns the pause mode of this socket
See also
- PySide6.QtWebSockets.QWebSocket.peerAddress()#
- Return type:
Returns the peer address
- PySide6.QtWebSockets.QWebSocket.peerName()#
- Return type:
str
Returns the peerName
- PySide6.QtWebSockets.QWebSocket.peerPort()#
- Return type:
quint16
Returns the peerport
- PySide6.QtWebSockets.QWebSocket.peerVerifyError(error)#
- Parameters:
error –
PySide6.QtNetwork.QSslError
QWebSocket
can emit this signal several times during the SSL handshake, before encryption has been established, to indicate that an error has occurred while establishing the identity of the peer. The error
is usually an indication that QWebSocket
is unable to securely identify the peer.
This signal provides you with an early indication when something’s wrong. By connecting to this signal, you can manually choose to tear down the connection from inside the connected slot before the handshake has completed. If no action is taken, QWebSocket
will proceed to emitting sslErrors()
.
See also
- PySide6.QtWebSockets.QWebSocket.ping([payload=QByteArray()])#
- Parameters:
payload –
PySide6.QtCore.QByteArray
Pings the server to indicate that the connection is still alive. Additional payload
can be sent along the ping message.
The size of the payload
cannot be bigger than 125. If it is larger, the payload
is clipped to 125 bytes.
Note
QWebSocket
and QWebSocketServer
handles ping requests internally, which means they automatically send back a pong response to the peer.
See also
- PySide6.QtWebSockets.QWebSocket.pong(elapsedTime, payload)#
- Parameters:
elapsedTime – int
payload –
PySide6.QtCore.QByteArray
Emitted when a pong message is received in reply to a previous ping. elapsedTime
contains the roundtrip time in milliseconds and payload
contains an optional payload that was sent with the ping.
See also
- Parameters:
authenticator –
PySide6.QtNetwork.QSslPreSharedKeyAuthenticator
This signal is emitted if the SSL/TLS handshake negotiates a PSK ciphersuite, and therefore a PSK authentication is then required.
When using PSK, the client must send to the server a valid identity and a valid pre shared key, in order for the SSL handshake to continue. Applications can provide this information in a slot connected to this signal, by filling in the passed authenticator
object according to their needs.
Note
Ignoring this signal, or failing to provide the required credentials, will cause the handshake to fail, and therefore the connection to be aborted.
Note
The authenticator
object is owned by the websocket and must not be deleted by the application.
See also
QSslPreSharedKeyAuthenticator
preSharedKeyAuthenticationRequired()
- PySide6.QtWebSockets.QWebSocket.proxy()#
- Return type:
Returns the currently configured proxy
See also
- PySide6.QtWebSockets.QWebSocket.proxyAuthenticationRequired(proxy, pAuthenticator)#
- Parameters:
proxy –
PySide6.QtNetwork.QNetworkProxy
pAuthenticator –
PySide6.QtNetwork.QAuthenticator
This signal can be emitted when a proxy
that requires authentication is used. The authenticator
object can then be filled in with the required details to allow authentication and continue the connection.
Note
It is not possible to use a QueuedConnection to connect to this signal, as the connection will fail if the authenticator has not been filled in with new information when the signal returns.
See also
QAuthenticator
QNetworkProxy
- PySide6.QtWebSockets.QWebSocket.readBufferSize()#
- Return type:
int
Returns the size in bytes of the readbuffer that is used by the socket.
See also
- PySide6.QtWebSockets.QWebSocket.readChannelFinished()#
This signal is emitted when the input (reading) stream is closed in this device. It is emitted as soon as the closing is detected.
See also
- PySide6.QtWebSockets.QWebSocket.request()#
- Return type:
Returns the request that was or will be used to open this socket.
- PySide6.QtWebSockets.QWebSocket.requestUrl()#
- Return type:
Returns the url the socket is connected to or will connect to.
- PySide6.QtWebSockets.QWebSocket.resourceName()#
- Return type:
str
Returns the name of the resource currently accessed.
- PySide6.QtWebSockets.QWebSocket.resume()#
Continues data transfer on the socket. This method should only be used after the socket has been set to pause upon notifications and a notification has been received. The only notification currently supported is sslErrors()
. Calling this method if the socket is not paused results in undefined behavior.
See also
- PySide6.QtWebSockets.QWebSocket.sendBinaryMessage(data)#
- Parameters:
data –
PySide6.QtCore.QByteArray
- Return type:
int
Sends the given data
over the socket as a binary message and returns the number of bytes actually sent.
See also
- PySide6.QtWebSockets.QWebSocket.sendTextMessage(message)#
- Parameters:
message – str
- Return type:
int
Sends the given message
over the socket as a text message and returns the number of bytes actually sent.
See also
- PySide6.QtWebSockets.QWebSocket.setMaskGenerator(maskGenerator)#
- Parameters:
maskGenerator –
PySide6.QtWebSockets.QMaskGenerator
Sets the generator to use for creating masks to maskGenerator
. The default QWebSocket
generator can be reset by supplying a nullptr. The mask generator can be changed at any time, even while the connection is open.
See also
- PySide6.QtWebSockets.QWebSocket.setMaxAllowedIncomingFrameSize(maxAllowedIncomingFrameSize)#
- Parameters:
maxAllowedIncomingFrameSize – int
Sets the maximum allowed size of an incoming websocket frame to maxAllowedIncomingFrameSize
. If an incoming frame exceeds this limit, the peer gets disconnected. The accepted range is between 0 and maxIncomingFrameSize()
, default is maxIncomingFrameSize()
. The purpose of this function is to avoid exhausting virtual memory.
See also
- PySide6.QtWebSockets.QWebSocket.setMaxAllowedIncomingMessageSize(maxAllowedIncomingMessageSize)#
- Parameters:
maxAllowedIncomingMessageSize – int
Sets the maximum allowed size of an incoming websocket message to maxAllowedIncomingMessageSize
. If an incoming message exceeds this limit, the peer gets disconnected. The accepted range is between 0 and maxIncomingMessageSize()
, default is maxIncomingMessageSize()
. The purpose of this function is to avoid exhausting virtual memory.
See also
- PySide6.QtWebSockets.QWebSocket.setOutgoingFrameSize(outgoingFrameSize)#
- Parameters:
outgoingFrameSize – int
Sets the maximum size of an outgoing websocket frame to outgoingFrameSize
. The accepted range is between 0 and maxOutgoingFrameSize()
, default is 512kB. The purpose of this function is to adapt to the maximum allowed frame size of the receiver.
See also
- PySide6.QtWebSockets.QWebSocket.setPauseMode(pauseMode)#
- Parameters:
pauseMode –
PauseModes
Controls whether to pause upon receiving a notification. The pauseMode
parameter specifies the conditions in which the socket should be paused.
The only notification currently supported is sslErrors()
. If set to PauseOnSslErrors, data transfer on the socket will be paused and needs to be enabled explicitly again by calling resume()
. By default, this option is set to PauseNever. This option must be called before connecting to the server, otherwise it will result in undefined behavior.
See also
- PySide6.QtWebSockets.QWebSocket.setProxy(networkProxy)#
- Parameters:
networkProxy –
PySide6.QtNetwork.QNetworkProxy
Sets the proxy to networkProxy
See also
- PySide6.QtWebSockets.QWebSocket.setReadBufferSize(size)#
- Parameters:
size – int
Sets the size of QWebSocket
‘s internal read buffer to be size
bytes.
If the buffer size is limited to a certain size, QWebSocket
won’t buffer more than this size of data. Exceptionally, a buffer size of 0 means that the read buffer is unlimited and all incoming data is buffered. This is the default. This option is useful if you only read the data at certain points in time (for example, in a real-time streaming application) or if you want to protect your socket against receiving too much data, which may eventually cause your application to run out of memory.
See also
- PySide6.QtWebSockets.QWebSocket.setSslConfiguration(sslConfiguration)#
- Parameters:
sslConfiguration –
PySide6.QtNetwork.QSslConfiguration
Sets the socket’s SSL configuration to be the contents of sslConfiguration
.
This function sets the local certificate, the ciphers, the private key and the CA certificates to those stored in sslConfiguration
. It is not possible to set the SSL-state related fields.
See also
- PySide6.QtWebSockets.QWebSocket.sslConfiguration()#
- Return type:
Returns the socket’s SSL configuration state. The default SSL configuration of a socket is to use the default ciphers, default CA certificates, no local private key or certificate. The SSL configuration also contains fields that can change with time without notice.
See also
- PySide6.QtWebSockets.QWebSocket.sslErrors(errors)#
- Parameters:
errors –
QWebSocket
emits this signal after the SSL handshake to indicate that one or more errors have occurred while establishing the identity of the peer. The errors are usually an indication that QWebSocket
is unable to securely identify the peer. Unless any action is taken, the connection will be dropped after this signal has been emitted. If you want to continue connecting despite the errors that have occurred, you must call ignoreSslErrors()
from inside a slot connected to this signal. If you need to access the error list at a later point, you can call sslErrors() (without arguments).
errors
contains one or more errors that prevent QWebSocket
from verifying the identity of the peer.
Note
You cannot use QueuedConnection
when connecting to this signal, or calling ignoreSslErrors()
will have no effect.
- PySide6.QtWebSockets.QWebSocket.state()#
- Return type:
Returns the current state of the socket.
- PySide6.QtWebSockets.QWebSocket.stateChanged(state)#
- Parameters:
state –
SocketState
This signal is emitted whenever QWebSocket
‘s state changes. The state
parameter is the new state.
Note
ConnectedState
is emitted after the handshake with the server has succeeded.
SocketState
is not a registered metatype, so for queued connections, you will have to register it with Q_REGISTER_METATYPE() and qRegisterMetaType()
.
See also
- PySide6.QtWebSockets.QWebSocket.subprotocol()#
- Return type:
str
Returns the used WebSocket protocol.
- PySide6.QtWebSockets.QWebSocket.textFrameReceived(frame, isLastFrame)#
- Parameters:
frame – str
isLastFrame – bool
This signal is emitted whenever a text frame is received. The frame
contains the data and isLastFrame
indicates whether this is the last frame of the complete message.
This signal can be used to process large messages frame by frame, instead of waiting for the complete message to arrive.
See also
- PySide6.QtWebSockets.QWebSocket.textMessageReceived(message)#
- Parameters:
message – str
This signal is emitted whenever a text message is received. The message
contains the received text.
See also
Returns the version the socket is currently using.