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Diffstat (limited to 'examples/network/doc/src/secureudpclient.qdoc')
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diff --git a/examples/network/doc/src/secureudpclient.qdoc b/examples/network/doc/src/secureudpclient.qdoc new file mode 100644 index 0000000000..dc8538cf85 --- /dev/null +++ b/examples/network/doc/src/secureudpclient.qdoc @@ -0,0 +1,124 @@ +/**************************************************************************** +** +** Copyright (C) 2018 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:FDL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU Free Documentation License Usage +** Alternatively, this file may be used under the terms of the GNU Free +** Documentation License version 1.3 as published by the Free Software +** Foundation and appearing in the file included in the packaging of +** this file. Please review the following information to ensure +** the GNU Free Documentation License version 1.3 requirements +** will be met: https://www.gnu.org/licenses/fdl-1.3.html. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \example secureudpclient + \title DTLS client + \ingroup examples-network + \brief This example demonstrates how to implement client-side DTLS connections. + + \image secureudpclient-example.png Screenshot of the DTLS client example. + + \note The DTLS client example is intended to be run alongside the \l{secureudpserver}{DTLS server} example. + + The example DTLS client can establish several DTLS connections to one + or many DTLS servers. A client-side DTLS connection is implemented by the + DtlsAssociation class. This class uses QUdpSocket to read and write datagrams + and QDtls for encryption: + + \snippet secureudpclient/association.h 0 + + The constructor sets the minimal TLS configuration for the new DTLS connection, + and sets the address and the port of the server: + + \dots + \snippet secureudpclient/association.cpp 1 + \dots + + The QDtls::handshakeTimeout() signal is connected to the handleTimeout() slot + to deal with packet loss and retransmission during the handshake phase: + + \dots + \snippet secureudpclient/association.cpp 2 + \dots + + To ensure we receive only the datagrams from the server, we connect our UDP socket to the server: + + \dots + \snippet secureudpclient/association.cpp 3 + \dots + + The QUdpSocket::readyRead() signal is connected to the readyRead() slot: + + \dots + \snippet secureudpclient/association.cpp 13 + \dots + + When a secure connection to a server is established, a DtlsAssociation object + will be sending short ping messages to the server, using a timer: + + \snippet secureudpclient/association.cpp 4 + + startHandshake() starts a handshake with the server: + + \snippet secureudpclient/association.cpp 5 + + The readyRead() slot reads a datagram sent by the server: + + \snippet secureudpclient/association.cpp 6 + + If the handshake was already completed, this datagram is decrypted: + + \snippet secureudpclient/association.cpp 7 + + otherwise, we try to continue the handshake: + + \snippet secureudpclient/association.cpp 8 + + When the handshake has completed, we send our first ping message: + + \snippet secureudpclient/association.cpp 9 + + The pskRequired() slot provides the Pre-Shared Key (PSK) needed during the handshake + phase: + + \snippet secureudpclient/association.cpp 14 + + \note For the sake of brevity, the definition of pskRequired() is oversimplified. + The documentation for the QSslPreSharedKeyAuthenticator class explains in detail + how this slot can be properly implemented. + + pingTimeout() sends an encrypted message to the server: + + \snippet secureudpclient/association.cpp 10 + + During the handshake phase the client must handle possible timeouts, which + can happen due to packet loss. The handshakeTimeout() slot retransmits + the handshake messages: + + \snippet secureudpclient/association.cpp 11 + + Before a client connection is destroyed, its DTLS connection must be shut down: + + \snippet secureudpclient/association.cpp 12 + + Error messages, informational messages, and decrypted responses from servers + are displayed by the UI: + + \snippet secureudpclient/mainwindow.cpp 0 +*/ + |