QDtls ¶

概要 ¶

详细描述 ¶

QDtls class can be used to establish a secure connection with a network peer using User Datagram Protocol (UDP). DTLS connection over essentially connectionless UDP means that two peers first have to successfully complete a TLS handshake by calling doHandshake() . After the handshake has completed, encrypted datagrams can be sent to the peer using writeDatagramEncrypted() . Encrypted datagrams coming from the peer can be decrypted by decryptDatagram() .

QDtls is designed to work with QUdpSocket 。由于 QUdpSocket can receive datagrams coming from different peers, an application must implement demultiplexing, forwarding datagrams coming from different peers to their corresponding instances of QDtls . An association between a network peer and its QDtls object can be established using the peer’s address and port number. Before starting a handshake, the application must set the peer’s address and port number using setPeer() .

QDtls does not read datagrams from QUdpSocket , this is expected to be done by the application, for example, in a slot attached to the readyRead() signal. Then, these datagrams must be processed by QDtls .

注意

QDtls does not 拥有所有权对于 QUdpSocket 对象。

Normally, several datagrams are to be received and sent by both peers during the handshake phase. Upon reading datagrams, server and client must pass these datagrams to doHandshake() until some error is found or handshakeState() 返回 HandshakeComplete :

// A client initiates a handshake:
QUdpSocket clientSocket;
QDtls clientDtls;
clientDtls.setPeer(address, port, peerName);
clientDtls.doHandshake(&clientSocket);
// A server accepting an incoming connection; address, port, clientHello are
// read by QUdpSocket::readDatagram():
QByteArray clientHello(serverSocket.pendingDatagramSize(), Qt::Uninitialized);
QHostAddress address;
quin16 port = {};
serverSocket.readDatagram(clientHello.data(), clientHello.size(), &address, &port);
QDtls serverDtls;
serverDtls.setPeer(address, port);
serverDtls.doHandshake(&serverSocket, clientHello);
// Handshake completion, both for server and client:
void DtlsConnection::continueHandshake(const QByteArray &datagram)
{
    if (dtls.doHandshake(&udpSocket, datagram)) {
        // Check handshake status:
        if (dtls.handshakeStatus() == QDlts::HandshakeComplete) {
            // Secure DTLS connection is now established.
        }
    } else {
        // Error handling.
    }
}
											

For a server, the first call to doHandshake() requires a non-empty datagram containing a ClientHello message. If the server also deploys QDtlsClientVerifier , the first ClientHello message is expected to be the one verified by QDtlsClientVerifier .

In case the peer’s identity cannot be validated during the handshake, the application must inspect errors returned by peerVerificationErrors() and then either ignore errors by calling ignoreVerificationErrors() or abort the handshake by calling abortHandshake() . If errors were ignored, the handshake can be resumed by calling resumeHandshake() .

After the handshake has been completed, datagrams can be sent to and received from the network peer securely:

// Sending an encrypted datagram:
dtlsConnection.writeDatagramEncrypted(&clientSocket, "Hello DTLS server!");
// Decryption:
QByteArray encryptedMessage(dgramSize);
socket.readDatagram(encryptedMessage.data(), dgramSize);
const QByteArray plainText = dtlsConnection.decryptDatagram(&socket, encryptedMessage);
											

A DTLS connection may be closed using shutdown() .

DtlsClient::~DtlsClient()
{
    clientDtls.shutdown(&clientSocket);
}
											

警告

It’s recommended to call shutdown() before destroying the client’s QDtls object if you are planning to re-use the same port number to connect to the server later. Otherwise, the server may drop incoming ClientHello messages, see RFC 6347, section 4.2.8 for more details and implementation hints.

If the server does not use QDtlsClientVerifier , it must configure its QDtls objects to disable the cookie verification procedure:

auto config = QSslConfiguration::defaultDtlsConfiguration();
config.setDtlsCookieVerificationEnabled(false);
// Some other customization ...
dtlsConnection.setDtlsConfiguration(config);
											

A server that uses cookie verification with non-default generator parameters must set the same parameters for its QDtls object before starting the handshake.

注意

The DTLS protocol leaves Path Maximum Transmission Unit (PMTU) discovery to the application. The application may provide QDtls with the MTU using setMtuHint() . This hint affects only the handshake phase, since only handshake messages can be fragmented and reassembled by the DTLS. All other messages sent by the application must fit into a single datagram.

注意

DTLS-specific headers add some overhead to application data further reducing the possible message size.

警告

A server configured to reply with HelloVerifyRequest will drop all fragmented ClientHello messages, never starting a handshake.

DTLS 服务器 and DTLS 客户端 examples illustrate how to use QDtls in applications.

另请参阅

QUdpSocket QDtlsClientVerifier HandshakeState QDtlsError QSslConfiguration

class QDtls ( mode [ , parent=None ] ) ¶

param parent

QObject

param mode

SslMode

创建 QDtls 对象， parent 会被传递给 QObject 构造函数。 mode is SslServerMode for a server-side DTLS connection or SslClientMode for a client.

另请参阅

sslMode() SslMode

PySide2.QtNetwork.QDtls. HandshakeState ¶

描述 DTLS 握手的当前状态。

This enum describes the current state of DTLS handshake for a QDtls 连接。

常量	描述
QDtls.HandshakeNotStarted	什么都没做。
QDtls.HandshakeInProgress	握手被初始，且到目前为止没有发现错误。
QDtls.PeerVerificationFailed	The identity of the peer can’t be established.
QDtls.HandshakeComplete	握手成功完成并建立加密连接。

另请参阅

doHandshake() handshakeState()

PySide2.QtNetwork.QDtls. abortHandshake ( socket ) ¶

参数

socket – QUdpSocket

返回类型

bool

Aborts the ongoing handshake. Returns true if one was on-going on socket ; otherwise, sets a suitable error and returns false.

另请参阅

doHandshake() resumeHandshake()

PySide2.QtNetwork.QDtls. decryptDatagram ( socket , dgram ) ¶

参数

• socket – QUdpSocket

• dgram – QByteArray

返回类型

QByteArray

Decrypts dgram and returns its contents as plain text. The handshake must be completed before datagrams can be decrypted. Depending on the type of the TLS message the connection may write into socket , which must be a valid pointer.

PySide2.QtNetwork.QDtls. doHandshake ( socket [ , dgram={} ] ) ¶

参数

• socket – QUdpSocket

• dgram – QByteArray

返回类型

bool

Starts or continues a DTLS handshake. socket must be a valid pointer. When starting a server-side DTLS handshake, dgram must contain the initial ClientHello message read from QUdpSocket . This function returns true if no error was found. Handshake state can be tested using handshakeState() . false return means some error occurred, use dtlsError() for more detailed information.

注意

If the identity of the peer can’t be established, the error is set to QDtlsError::PeerVerificationError. If you want to ignore verification errors and continue connecting, you must call ignoreVerificationErrors() and then resumeHandshake() . If the errors cannot be ignored, you must call abortHandshake() .

if (!dtls.doHandshake(&socket, dgram)) {
    if (dtls.dtlsError() == QDtlsError::PeerVerificationError)
        dtls.abortAfterError(&socket);
}
											

另请参阅

handshakeState() dtlsError() ignoreVerificationErrors() resumeHandshake() abortHandshake()

PySide2.QtNetwork.QDtls. dtlsConfiguration ( ) ¶

返回类型

QSslConfiguration

Returns either the default DTLS configuration or the configuration set by an earlier call to setDtlsConfiguration() .

另请参阅

setDtlsConfiguration() defaultDtlsConfiguration()

PySide2.QtNetwork.QDtls. dtlsError ( ) ¶

返回类型

QDtlsError

Returns the last error encountered by the connection or QDtlsError::NoError.

另请参阅

dtlsErrorString() QDtlsError

PySide2.QtNetwork.QDtls. dtlsErrorString ( ) ¶

返回类型

unicode

Returns a textual description for the last error encountered by the connection or empty string.

另请参阅

dtlsError()

PySide2.QtNetwork.QDtls. handleTimeout ( socket ) ¶

参数

socket – QUdpSocket

返回类型

bool

If a timeout occures during the handshake, the handshakeTimeout() signal is emitted. The application must call to retransmit handshake messages; returns true if a timeout has occurred, false otherwise. socket must be a valid pointer.

另请参阅

handshakeTimeout()

PySide2.QtNetwork.QDtls. handshakeState ( ) ¶

返回类型

HandshakeState

返回当前握手状态为此 QDtls .

另请参阅

doHandshake() HandshakeState

PySide2.QtNetwork.QDtls. handshakeTimeout ( ) ¶

PySide2.QtNetwork.QDtls. ignoreVerificationErrors ( errorsToIgnore ) ¶

参数

errorsToIgnore –

此方法告诉 QDtls to ignore only the errors given in errorsToIgnore .

If, for instance, you want to connect to a server that uses a self-signed certificate, consider the following snippet:

QList<QSslCertificate> cert = QSslCertificate::fromPath(QLatin1String("server-certificate.pem"));
QSslError error(QSslError::SelfSignedCertificate, cert.at(0));
QList<QSslError> expectedSslErrors;
expectedSslErrors.append(error);
QDtls dtls;
dtls.ignoreVerificationErrors(expectedSslErrors);
dtls.doHandshake(udpSocket);
											

You can also call this function after doHandshake() encountered the QDtlsError::PeerVerificationError error, and then resume the handshake by calling resumeHandshake() .

Later 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.

另请参阅

doHandshake() resumeHandshake() QSslError

PySide2.QtNetwork.QDtls. isConnectionEncrypted ( ) ¶

返回类型

bool

返回 true if DTLS handshake completed successfully.

另请参阅

doHandshake() handshakeState()

PySide2.QtNetwork.QDtls. mtuHint ( ) ¶

返回类型

quint16

Returns the value previously set by setMtuHint() . The default value is 0.

另请参阅

setMtuHint()

PySide2.QtNetwork.QDtls. peerAddress ( ) ¶

返回类型

QHostAddress

Returns the peer’s address, set by setPeer() ，或 Null .

另请参阅

setPeer()

PySide2.QtNetwork.QDtls. peerPort ( ) ¶

返回类型

quint16

Returns the peer’s port number, set by setPeer() , or 0.

另请参阅

setPeer()

PySide2.QtNetwork.QDtls. peerVerificationErrors ( ) ¶

返回类型

Returns errors found while establishing the identity of the peer.

If you want to continue connecting despite the errors that have occurred, you must call ignoreVerificationErrors() .

PySide2.QtNetwork.QDtls. peerVerificationName ( ) ¶

返回类型

unicode

Returns the host name set by setPeer() or setPeerVerificationName() . The default value is an empty string.

另请参阅

setPeerVerificationName() setPeer()

PySide2.QtNetwork.QDtls. pskRequired ( authenticator ) ¶

参数

authenticator – QSslPreSharedKeyAuthenticator

PySide2.QtNetwork.QDtls. resumeHandshake ( socket ) ¶

参数

socket – QUdpSocket

返回类型

bool

If peer verification errors were ignored during the handshake, resumes and completes the handshake and returns true . socket must be a valid pointer. Returns false if the handshake could not be resumed.

另请参阅

doHandshake() abortHandshake() peerVerificationErrors() ignoreVerificationErrors()

PySide2.QtNetwork.QDtls. sessionCipher ( ) ¶

返回类型

QSslCipher

Returns the cryptographic cipher used by this connection, or a null cipher if the connection isn’t encrypted. The cipher for the session is selected during the handshake phase. The cipher is used to encrypt and decrypt data.

QSslConfiguration provides functions for setting the ordered list of ciphers from which the handshake phase will eventually select the session cipher. This ordered list must be in place before the handshake phase begins.

另请参阅

QSslConfiguration setDtlsConfiguration() dtlsConfiguration()

PySide2.QtNetwork.QDtls. sessionProtocol ( ) ¶

返回类型

SslProtocol

Returns the DTLS protocol version used by this connection, or UnknownProtocol if the connection isn’t encrypted yet. The protocol for the connection is selected during the handshake phase.

setDtlsConfiguration() can set the preferred version before the handshake starts.

另请参阅

setDtlsConfiguration() QSslConfiguration defaultDtlsConfiguration() setProtocol()

PySide2.QtNetwork.QDtls. setDtlsConfiguration ( configuration ) ¶

参数

configuration – QSslConfiguration

返回类型

bool

Sets the connection’s TLS configuration from configuration 并返回 true 若成功。

注意

This function must be called before the handshake starts.

另请参阅

dtlsConfiguration() doHandshake()

PySide2.QtNetwork.QDtls. setMtuHint ( mtuHint ) ¶

参数

mtuHint – quint16

mtuHint is the maximum transmission unit (MTU), either discovered or guessed by the application. The application is not required to set this value.

另请参阅

mtuHint() PathMtuSocketOption

PySide2.QtNetwork.QDtls. setPeer ( address , port [ , verificationName={} ] ) ¶

参数

• address – QHostAddress

• port – quint16

• verificationName – unicode

返回类型

bool

Sets the peer’s address, port , and host name and returns true 若成功。 address must not be null, multicast, or broadcast. verificationName is the host name used for the certificate validation.

另请参阅

peerAddress() peerPort() peerVerificationName()

PySide2.QtNetwork.QDtls. setPeerVerificationName ( name ) ¶

参数

name – unicode

返回类型

bool

Sets the host name that will be used for the certificate validation and returns true 若成功。

注意

This function must be called before the handshake starts.

另请参阅

peerVerificationName() setPeer()

PySide2.QtNetwork.QDtls. shutdown ( socket ) ¶

参数

socket – QUdpSocket

返回类型

bool

Sends an encrypted shutdown alert message and closes the DTLS connection. Handshake state changes to HandshakeNotStarted . socket must be a valid pointer. This function returns true 当成功时。

另请参阅

doHandshake()

PySide2.QtNetwork.QDtls. sslMode ( ) ¶

返回类型

SslMode

返回 SslServerMode for a server-side connection and SslClientMode for a client.

另请参阅

QDtls() SslMode

PySide2.QtNetwork.QDtls. writeDatagramEncrypted ( socket , dgram ) ¶

参数

• socket – QUdpSocket

• dgram – QByteArray

返回类型

qint64

Encrypts dgram and writes the encrypted data into socket . Returns the number of bytes written, or -1 in case of error. The handshake must be completed before writing encrypted data. socket must be a valid pointer.

另请参阅

doHandshake() handshakeState() isConnectionEncrypted() dtlsError()