Add a secure UDP server example

It's a simple DTLS server, implemented with QUdpSocket,
QDtlsClientVerifier and QDtls. The server is configured
to use PSK only (it has no certificate/key).

The server uses a single QUdpSocket socket and
de-multiplexes UDP datagrams internally (thus
it can work with several clients simultaneously).

Future update will probably add more options (like
configuring with certificate/key, etc). For now -
it's as minimalistic and simple as possible.

Task-number: QTBUG-67596
Change-Id: Ic7d18dbab6dbcc9ed44c82e69a2b364df24aa256
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

1 files changed, 109 insertions, 0 deletions

diff --git a/examples/network/secureudpserver/server.h b/examples/network/secureudpserver/server.h
new file mode 100644
index 0000000000..33444f7407
--- /dev/null
+++ b/examples/network/secureudpserver/server.h
@@ -0,0 +1,109 @@
+/****************************************************************************
+**
+** 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."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#ifndef SERVER_H
+#define SERVER_H
+
+#include <QtCore>
+#include <QtNetwork>
+
+#include <vector>
+
+QT_BEGIN_NAMESPACE
+
+class DtlsServer : public QObject
+{
+    Q_OBJECT
+
+public:
+
+    DtlsServer();
+    ~DtlsServer();
+
+    bool listen(const QHostAddress &address, quint16 port);
+    bool isListening() const;
+    void close();
+
+signals:
+
+    void errorMessage(const QString &message);
+    void warningMessage(const QString &message);
+    void infoMessage(const QString &message);
+
+    void datagramReceived(const QString &peerInfo, const QByteArray &cipherText,
+                          const QByteArray &plainText);
+
+private slots:
+
+    void readyRead();
+    void pskRequired(QSslPreSharedKeyAuthenticator *auth);
+
+private:
+
+    void handleNewConnection(const QHostAddress &peerAddress, quint16 peerPort,
+                             const QByteArray &clientHello);
+
+    using DtlsConnection = QSharedPointer<QDtls>;
+    void doHandshake(DtlsConnection newConnection, const QByteArray &clientHello);
+    void decryptDatagram(DtlsConnection connection, const QByteArray &clientMessage);
+    void shutdown();
+
+    bool listening = false;
+    QUdpSocket serverSocket;
+
+    QSslConfiguration serverConfiguration;
+    QDtlsClientVerifier cookieSender;
+    QVector<DtlsConnection> knownClients;
+
+    Q_DISABLE_COPY(DtlsServer)
+};
+
+QT_END_NAMESPACE
+
+#endif // SERVER_H