QSslServer: Make sure maxPendingConnections applies to all sockets

Not just the ones we added to the pending sockets list

Pick-to: 6.4
Change-Id: I0a0016fe39df7ca2fc3f0c4e4111195bc6d90198
Reviewed-by: Konrad Kujawa <konrad.kujawa@qt.io>
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/network/socket/qtcpserver.cpp

@@ -172,7 +172,7 @@ void QTcpServerPrivate::readNotification()
 {
     Q_Q(QTcpServer);
     for (;;) {
-        if (pendingConnections.count() >= maxConnections) {
+        if (totalPendingConnections() >= maxConnections) {
 #if defined (QTCPSERVER_DEBUG)
             qDebug("QTcpServerPrivate::_q_processIncomingConnection() too many connections");
 #endif
@@ -205,6 +205,20 @@ void QTcpServerPrivate::readNotification()
     }
 }
 
+/*!
+    \internal
+    Return the amount of sockets currently in queue for the server.
+    This is to make maxPendingConnections work properly with servers that don't
+    necessarily have 'ready-to-go' sockets as soon as they connect,
+    e.g. QSslServer.
+    By default we just return pendingConnections.size(), which is equivalent to
+    what it did before.
+*/
+int QTcpServerPrivate::totalPendingConnections() const
+{
+    return int(pendingConnections.size());
+}
+
 /*!
     Constructs a QTcpServer object.
 

src/network/socket/qtcpserver_p.h

@@ -56,6 +56,7 @@ public:
 #endif
 
     virtual void configureCreatedSocket();
+    virtual int totalPendingConnections() const;
 
     // from QAbstractSocketEngineReceiver
     void readNotification() override;

src/network/ssl/qsslserver.cpp

@@ -350,6 +350,12 @@ void QSslServerPrivate::removeSocketData(quintptr socket)
     }
 }
 
+int QSslServerPrivate::totalPendingConnections() const
+{
+    // max pending connections is int, so this cannot exceed that
+    return QTcpServerPrivate::totalPendingConnections() + int(socketData.size());
+}
+
 void QSslServerPrivate::checkClientHelloAndContinue()
 {
     Q_Q(QSslServer);

src/network/ssl/qsslserver_p.h

@@ -38,6 +38,7 @@ public:
     void initializeHandshakeProcess(QSslSocket *socket);
     void removeSocketData(quintptr socket);
     void handleHandshakeTimedOut(QSslSocket *socket);
+    int totalPendingConnections() const override;
 
     struct SocketData {
         QMetaObject::Connection readyReadConnection;

tests/auto/network/ssl/qsslserver/tst_qsslserver.cpp

@@ -25,6 +25,7 @@ private slots:
 #endif
     void plaintextClient();
     void quietClient();
+    void manyQuietClients();
 
 private:
     QString testDataDir;
@@ -487,6 +488,34 @@ void tst_QSslServer::quietClient()
     QCOMPARE(serverPeerPort, clientLocalPort);
 }
 
+void tst_QSslServer::manyQuietClients()
+{
+    QSslConfiguration serverConfiguration = selfSignedServerQSslConfiguration();
+    SslServerSpy server(serverConfiguration);
+    constexpr qsizetype ExpectedConnections = 5;
+    server.server.setMaxPendingConnections(ExpectedConnections);
+    QVERIFY(server.server.listen());
+
+    // Connect one socket encrypted so we have a socket in the regular queue
+    QSslSocket tlsSocket;
+    QObject::connect(&tlsSocket, &QSslSocket::sslErrors, &tlsSocket,
+                     qOverload<const QList<QSslError> &>(&QSslSocket::ignoreSslErrors));
+    tlsSocket.connectToHostEncrypted("127.0.0.1", server.server.serverPort());
+
+    // Then we connect a bunch of TCP sockets who will not send any data at all
+    std::array<QTcpSocket, size_t(ExpectedConnections) * 4> sockets;
+    for (QTcpSocket &socket : sockets)
+        socket.connectToHost(QHostAddress::LocalHost, server.server.serverPort());
+    QTest::qWait(500); // some leeway to let connections try to connect...
+
+    // I happen to know the sockets are all children of the server, so let's see
+    // how many are created:
+    qsizetype connectedCount = server.server.findChildren<QSslSocket *>().size();
+    QCOMPARE(connectedCount, ExpectedConnections);
+    // 1 socket is ready and pending
+    QCOMPARE(server.pendingConnectionAvailableSpy.size(), 1);
+}
+
 QTEST_MAIN(tst_QSslServer)
 
 #include "tst_qsslserver.moc"