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// Copyright (C) 2018 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
//! [0]
class DtlsServer : public QObject
{
public:
bool listen(const QHostAddress &address, quint16 port);
// ...
private:
void readyRead();
// ...
QUdpSocket serverSocket;
QDtlsClientVerifier verifier;
// ...
};
bool DtlsServer::listen(const QHostAddress &serverAddress, quint16 serverPort)
{
if (serverSocket.bind(serverAddress, serverPort))
connect(&serverSocket, &QUdpSocket::readyRead, this, &DtlsServer::readyRead);
return serverSocket.state() == QAbstractSocket::BoundState;
}
void DtlsServer::readyRead()
{
QByteArray dgram(serverSocket.pendingDatagramSize(), Qt::Uninitialized);
QHostAddress address;
quint16 port = {};
serverSocket.readDatagram(dgram.data(), dgram.size(), &address, &port);
if (verifiedClients.contains({address, port}) {
// This client was verified previously, we either continue the
// handshake or decrypt the incoming message.
} else if (verifier.verifyClient(&serverSocket, dgram, address, port)) {
// Apparently we have a real DTLS client who wants to send us
// encrypted datagrams. Remember this client as verified
// and proceed with a handshake.
} else {
// No matching cookie was found in the incoming datagram,
// verifyClient() has sent a ClientVerify message.
// We'll hear from the client again soon, if they're real.
}
}
//! [0]
//! [1]
void DtlsServer::updateServerSecret()
{
const QByteArray newSecret(generateCryptoStrongSecret());
if (newSecret.size()) {
usedCookies.append(newSecret);
verifier.setCookieGeneratorParameters({QCryptographicHash::Sha1, newSecret});
}
}
//! [1]
//! [2]
if (!verifier.verifyClient(&socket, message, address, port)) {
switch (verifyClient.dtlsError()) {
case QDtlsError::NoError:
// Not verified yet, but no errors found and we have to wait for the next
// message from this client.
return;
case QDtlsError::TlsInitializationError:
// This error is fatal, nothing we can do about it.
// Probably, quit the server after reporting the error.
return;
case QDtlsError::UnderlyingSocketError:
// There is some problem in QUdpSocket, handle it (see QUdpSocket::error())
return;
case QDtlsError::InvalidInputParameters:
default:
Q_UNREACHABLE();
}
}
//! [2]
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