server.cpp Example File

secureudpserver/server.cpp
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#include "server.h" #include <algorithm> namespace { QString peer_info(const QHostAddress &address, quint16 port) { const static QString info = QStringLiteral("(%1:%2)"); return info.arg(address.toString()).arg(port); } QString connection_info(QSharedPointer<QDtls> connection) { QString info(DtlsServer::tr("Session cipher: ")); info += connection->sessionCipher().name(); info += DtlsServer::tr("; session protocol: "); switch (connection->sessionProtocol()) { case QSsl::DtlsV1_0: info += DtlsServer::tr("DTLS 1.0."); break; case QSsl::DtlsV1_2: info += DtlsServer::tr("DTLS 1.2."); break; case QSsl::DtlsV1_2OrLater: info += DtlsServer::tr("DTLS 1.2 or later."); break; default: info += DtlsServer::tr("Unknown protocol."); } return info; } } // unnamed namespace DtlsServer::DtlsServer() { connect(&serverSocket, &QAbstractSocket::readyRead, this, &DtlsServer::readyRead); serverConfiguration = QSslConfiguration::defaultDtlsConfiguration(); serverConfiguration.setPreSharedKeyIdentityHint("Qt DTLS example server"); serverConfiguration.setPeerVerifyMode(QSslSocket::VerifyNone); } DtlsServer::~DtlsServer() { shutdown(); } bool DtlsServer::listen(const QHostAddress &address, quint16 port) { if (address != serverSocket.localAddress() || port != serverSocket.localPort()) { shutdown(); listening = serverSocket.bind(address, port); if (!listening) emit errorMessage(serverSocket.errorString()); } else { listening = true; } return listening; } bool DtlsServer::isListening() const { return listening; } void DtlsServer::close() { listening = false; } void DtlsServer::readyRead() { const qint64 bytesToRead = serverSocket.pendingDatagramSize(); if (bytesToRead <= 0) { emit warningMessage(tr("A spurious read notification")); return; } QByteArray dgram(bytesToRead, Qt::Uninitialized); QHostAddress peerAddress; quint16 peerPort = 0; const qint64 bytesRead = serverSocket.readDatagram(dgram.data(), dgram.size(), &peerAddress, &peerPort); if (bytesRead <= 0) { emit warningMessage(tr("Failed to read a datagram: ") + serverSocket.errorString()); return; } dgram.resize(bytesRead); if (peerAddress.isNull() || !peerPort) { emit warningMessage(tr("Failed to extract peer info (address, port)")); return; } const auto client = std::find_if(knownClients.begin(), knownClients.end(), [&](const DtlsConnection &connection){ return connection->peerAddress() == peerAddress && connection->peerPort() == peerPort; }); if (client == knownClients.end()) return handleNewConnection(peerAddress, peerPort, dgram); if ((*client)->isConnectionEncrypted()) { decryptDatagram(*client, dgram); if ((*client)->dtlsError() == QDtlsError::RemoteClosedConnectionError) knownClients.erase(client); return; } doHandshake(*client, dgram); } void DtlsServer::pskRequired(QSslPreSharedKeyAuthenticator *auth) { Q_ASSERT(auth); emit infoMessage(tr("PSK callback, received a client's identity: '%1'") .arg(QString::fromLatin1(auth->identity()))); auth->setPreSharedKey(QByteArrayLiteral("\x1a\x2b\x3c\x4d\x5e\x6f")); } void DtlsServer::handleNewConnection(const QHostAddress &peerAddress, quint16 peerPort, const QByteArray &clientHello) { if (!listening) return; const QString peerInfo = peer_info(peerAddress, peerPort); if (cookieSender.verifyClient(&serverSocket, clientHello, peerAddress, peerPort)) { emit infoMessage(peerInfo + tr(": verified, starting a handshake")); DtlsConnection newConnection(new QDtls(QSslSocket::SslServerMode)); newConnection->setDtlsConfiguration(serverConfiguration); newConnection->setPeer(peerAddress, peerPort); newConnection->connect(newConnection.data(), &QDtls::pskRequired, this, &DtlsServer::pskRequired); knownClients.push_back(newConnection); doHandshake(newConnection, clientHello); } else if (cookieSender.dtlsError() != QDtlsError::NoError) { emit errorMessage(tr("DTLS error: ") + cookieSender.dtlsErrorString()); } else { emit infoMessage(peerInfo + tr(": not verified yet")); } } void DtlsServer::doHandshake(DtlsConnection newConnection, const QByteArray &clientHello) { const bool result = newConnection->doHandshake(&serverSocket, clientHello); if (!result) { emit errorMessage(newConnection->dtlsErrorString()); return; } const QString peerInfo = peer_info(newConnection->peerAddress(), newConnection->peerPort()); switch (newConnection->handshakeState()) { case QDtls::HandshakeInProgress: emit infoMessage(peerInfo + tr(": handshake is in progress ...")); break; case QDtls::HandshakeComplete: emit infoMessage(tr("Connection with %1 encrypted. %2") .arg(peerInfo, connection_info(newConnection))); break; default: Q_UNREACHABLE(); } } void DtlsServer::decryptDatagram(DtlsConnection connection, const QByteArray &clientMessage) { Q_ASSERT(connection->isConnectionEncrypted()); const QString peerInfo = peer_info(connection->peerAddress(), connection->peerPort()); const QByteArray dgram = connection->decryptDatagram(&serverSocket, clientMessage); if (dgram.size()) { emit datagramReceived(peerInfo, clientMessage, dgram); connection->writeDatagramEncrypted(&serverSocket, tr("to %1: ACK").arg(peerInfo).toLatin1()); } else if (connection->dtlsError() == QDtlsError::NoError) { emit warningMessage(peerInfo + ": " + tr("0 byte dgram, could be a re-connect attempt?")); } else { emit errorMessage(peerInfo + ": " + connection->dtlsErrorString()); } } void DtlsServer::shutdown() { for (DtlsConnection &connection : knownClients) connection->shutdown(&serverSocket); knownClients.clear(); serverSocket.close(); }

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