association.cpp Example File

secureudpclient/association.cpp
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#include "association.h" DtlsAssociation::DtlsAssociation(const QHostAddress &address, quint16 port, const QString &connectionName) : name(connectionName), crypto(QSslSocket::SslClientMode) { auto configuration = QSslConfiguration::defaultDtlsConfiguration(); configuration.setPeerVerifyMode(QSslSocket::VerifyNone); crypto.setPeer(address, port); crypto.setDtlsConfiguration(configuration); connect(&crypto, &QDtls::handshakeTimeout, this, &DtlsAssociation::handshakeTimeout); connect(&crypto, &QDtls::pskRequired, this, &DtlsAssociation::pskRequired); socket.connectToHost(address.toString(), port); connect(&socket, &QUdpSocket::readyRead, this, &DtlsAssociation::readyRead); pingTimer.setInterval(5000); connect(&pingTimer, &QTimer::timeout, this, &DtlsAssociation::pingTimeout); } DtlsAssociation::~DtlsAssociation() { if (crypto.isConnectionEncrypted()) crypto.shutdown(&socket); } void DtlsAssociation::startHandshake() { if (socket.state() != QAbstractSocket::ConnectedState) { emit infoMessage(tr("%1: connecting UDP socket first ...").arg(name)); connect(&socket, &QAbstractSocket::connected, this, &DtlsAssociation::udpSocketConnected); return; } if (!crypto.doHandshake(&socket)) emit errorMessage(tr("%1: failed to start a handshake - %2").arg(name, crypto.dtlsErrorString())); else emit infoMessage(tr("%1: starting a handshake").arg(name)); } void DtlsAssociation::udpSocketConnected() { emit infoMessage(tr("%1: UDP socket is now in ConnectedState, continue with handshake ...").arg(name)); startHandshake(); } void DtlsAssociation::readyRead() { QByteArray dgram(socket.pendingDatagramSize(), Qt::Uninitialized); const qint64 bytesRead = socket.readDatagram(dgram.data(), dgram.size()); if (bytesRead <= 0) { emit warningMessage(tr("%1: spurious read notification?").arg(name)); return; } dgram.resize(bytesRead); if (crypto.isConnectionEncrypted()) { const QByteArray plainText = crypto.decryptDatagram(&socket, dgram); if (plainText.size()) { emit serverResponse(name, dgram, plainText); return; } if (crypto.dtlsError() == QDtlsError::RemoteClosedConnectionError) { emit errorMessage(tr("%1: shutdown alert received").arg(name)); socket.close(); pingTimer.stop(); return; } emit warningMessage(tr("%1: zero-length datagram received?").arg(name)); } else { if (!crypto.doHandshake(&socket, dgram)) { emit errorMessage(tr("%1: handshake error - %2").arg(name, crypto.dtlsErrorString())); return; } if (crypto.isConnectionEncrypted()) { emit infoMessage(tr("%1: encrypted connection established!").arg(name)); pingTimer.start(); pingTimeout(); } else { emit infoMessage(tr("%1: continuing with handshake ...").arg(name)); } } } void DtlsAssociation::handshakeTimeout() { emit warningMessage(tr("%1: handshake timeout, trying to re-transmit").arg(name)); if (!crypto.handleTimeout(&socket)) emit errorMessage(tr("%1: failed to re-transmit - %2").arg(name, crypto.dtlsErrorString())); } void DtlsAssociation::pskRequired(QSslPreSharedKeyAuthenticator *auth) { Q_ASSERT(auth); emit infoMessage(tr("%1: providing pre-shared key ...").arg(name)); 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(tr("%1: failed to send a ping - %2").arg(name, crypto.dtlsErrorString())); pingTimer.stop(); return; } ++ping; }

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