From 033a1a279311fd2eda02e4c90657542f688b5f8b Mon Sep 17 00:00:00 2001 From: Timur Pocheptsov Date: Fri, 23 Mar 2018 12:30:31 +0100 Subject: Add a secure UDP client example A simple application that establishes DTLS connection(s) and sends/receives datagrams. Class DtlsAssociation is essentially a QUdpSocket|QDtls pair: it initiates a handshake, handles timeouts and errors. After establishing an encrypted connection it sends messages to the server and processes responses. Task-number: QTBUG-67596 Change-Id: I92d481b7dfd2459e6a93c754b338a2e897a7feaf Reviewed-by: Timur Pocheptsov --- examples/network/secureudpclient/association.cpp | 158 +++++++++++++++++++++++ 1 file changed, 158 insertions(+) create mode 100644 examples/network/secureudpclient/association.cpp (limited to 'examples/network/secureudpclient/association.cpp') diff --git a/examples/network/secureudpclient/association.cpp b/examples/network/secureudpclient/association.cpp new file mode 100644 index 0000000000..11f52ba96c --- /dev/null +++ b/examples/network/secureudpclient/association.cpp @@ -0,0 +1,158 @@ +/**************************************************************************** +** +** Copyright (C) 2018 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the examples of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:BSD$ +** 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. +** +** BSD License Usage +** Alternatively, you may use this file under the terms of the BSD license +** as follows: +** +** "Redistribution and use in source and binary forms, with or without +** modification, are permitted provided that the following conditions are +** met: +** * Redistributions of source code must retain the above copyright +** notice, this list of conditions and the following disclaimer. +** * Redistributions in binary form must reproduce the above copyright +** notice, this list of conditions and the following disclaimer in +** the documentation and/or other materials provided with the +** distribution. +** * Neither the name of The Qt Company Ltd nor the names of its +** contributors may be used to endorse or promote products derived +** from this software without specific prior written permission. +** +** +** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "association.h" + +QT_BEGIN_NAMESPACE + +DtlsAssociation::DtlsAssociation(const QHostAddress &address, quint16 port, + const QString &connectionName) + : name(connectionName), + crypto(QSslSocket::SslClientMode) +{ + auto configuration = QSslConfiguration::defaultDtlsConfiguration(); + configuration.setPeerVerifyMode(QSslSocket::VerifyNone); + crypto.setRemote(address, port); + crypto.setDtlsConfiguration(configuration); + + connect(&crypto, &QDtls::handshakeTimeout, this, &DtlsAssociation::handshakeTimeout); + connect(&crypto, &QDtls::pskRequired, this, &DtlsAssociation::pskRequired); + + connect(&socket, &QUdpSocket::readyRead, this, &DtlsAssociation::readyRead); + + pingTimer.setInterval(5000); + connect(&pingTimer, &QTimer::timeout, this, &DtlsAssociation::pingTimeout); +} + +DtlsAssociation::~DtlsAssociation() +{ + if (crypto.connectionEncrypted()) + crypto.sendShutdownAlert(&socket); +} + +void DtlsAssociation::startHandshake() +{ + if (!crypto.doHandshake(&socket, {})) + emit errorMessage(name + tr(": failed to start a handshake - ") + crypto.dtlsErrorString()); + else + emit infoMessage(name + tr(": starting a handshake")); +} + +void DtlsAssociation::readyRead() +{ + QByteArray dgram(socket.pendingDatagramSize(), '\0'); + const qint64 bytesRead = socket.readDatagram(dgram.data(), dgram.size()); + if (bytesRead <= 0) { + emit warningMessage(name + tr(": spurious read notification?")); + return; + } + + dgram.resize(bytesRead); + if (crypto.connectionEncrypted()) { + const QByteArray plainText = crypto.decryptDatagram(&socket, dgram); + if (plainText.size()) { + emit serverResponse(name, dgram, plainText); + pingTimer.start(); + return; + } + + if (crypto.dtlsError() == QDtlsError::RemoteClosedConnectionError) { + emit errorMessage(name + tr(": shutdown alert received")); + socket.close(); + pingTimer.stop(); + return; + } + + emit warningMessage(name + tr(": zero-length datagram received?")); + } else { + if (!crypto.doHandshake(&socket, dgram)) { + emit errorMessage(name + tr(": handshake error - ") + crypto.dtlsErrorString()); + return; + } + if (crypto.connectionEncrypted()) { + emit infoMessage(name + tr(": encrypted connection established!")); + pingTimer.start(); + pingTimeout(); + } else { + emit infoMessage(name + tr(": continuing with handshake ...")); + } + } +} + +void DtlsAssociation::handshakeTimeout() +{ + emit warningMessage(name + tr(": handshake timeout, trying to re-transmit")); + if (!crypto.handleTimeout(&socket)) + emit errorMessage(name + tr(": failed to re-transmit - ") + crypto.dtlsErrorString()); +} + +void DtlsAssociation::pskRequired(QSslPreSharedKeyAuthenticator *auth) +{ + Q_ASSERT(auth); + + emit infoMessage(name + tr(": providing pre-shared key ...")); + auth->setIdentity(name.toLatin1()); + auth->setPreSharedKey(QByteArrayLiteral("\x1a\x2b\x3c\x4d\x5e\x6f")); +} + +void DtlsAssociation::pingTimeout() +{ + static const QString message = QStringLiteral("I am %1, please, accept our ping %2"); + const qint64 written = crypto.writeDatagramEncrypted(&socket, message.arg(name).arg(ping).toLatin1()); + if (written <= 0) { + emit errorMessage(name + tr(": failed to send a ping - ") + crypto.dtlsErrorString()); + pingTimer.stop(); + return; + } + + ++ping; +} + +QT_END_NAMESPACE -- cgit v1.2.3