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  1. Qt
  2. QTBUG-57026

ssl websocketserver stops accepting new connections

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    • Icon: Bug Bug
    • Resolution: Done
    • Icon: P1: Critical P1: Critical
    • 5.14
    • 5.6.2, 5.7.0, 5.8.0 Beta
    • WebSockets
    • None
    • 2e54dbe86eac61e87782a138dbcc158cb6b10cd9

      Many connection attempts to a SSL-Websocketserver with a non-SSL Websocket causes the Websocketserver to accept any new connections.

      I already looked into the server code. The reason for this behaviour is caused by this section:

      websockets/sslserver.cpp
      [...]
void QSslServer::incomingConnection(qintptr socket)
{
    QSslSocket *pSslSocket = new QSslSocket();

    if (Q_LIKELY(pSslSocket)) {
        pSslSocket->setSslConfiguration(m_sslConfiguration);

        if (Q_LIKELY(pSslSocket->setSocketDescriptor(socket))) {
            connect(pSslSocket, &QSslSocket::peerVerifyError, this, &QSslServer::peerVerifyError);

            typedef void (QSslSocket::* sslErrorsSignal)(const QList<QSslError> &);
            connect(pSslSocket, static_cast<sslErrorsSignal>(&QSslSocket::sslErrors),
                    this, &QSslServer::sslErrors);
            connect(pSslSocket, &QSslSocket::encrypted, this, &QSslServer::newEncryptedConnection);
            connect(pSslSocket, &QSslSocket::preSharedKeyAuthenticationRequired, this, &QSslServer::preSharedKeyAuthenticationRequired);

            addPendingConnection(pSslSocket);

            pSslSocket->startServerEncryption();
        } else {
           delete pSslSocket;
        }
    }
}
[...]

      The new socket is appended to the queue with addPendingConnection. But the signal QSslSocket::encrypted is never emitted, so the connection never gets dequeued with nextPendingConnection in QWebSocketServerPrivate::onNewConnection. As a result, QTcpServer stops accepting new connections when maxPendingConnections is reached.

      This can be reproduced with SSL Echo Client Example. I've modifed the code accordingly:

      sslechoclient/main.cpp
      // Tested with SslEchClient changed
// void SslEchoClient::onTextMessageReceived(QString message)
// {
//     qDebug() << "Message received:" << message;
//     //qApp->quit(); -- disabled
// }

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    new SslEchoClient(QUrl(QStringLiteral("wss://localhost:1234")));

    for (int i = 0; i < 40; i++)
        new SslEchoClient(QUrl(QStringLiteral("ws://localhost:1234")));

    QTimer::singleShot(2500, [&] {
        a.quit();
    });

    return a.exec();
}

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            hvoigt Heiko Voigt
            hfx Hubert Feurstein
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              Created:
              Updated:
              Resolved:

                There is 1 open Gerrit change