QAbstractSocket: do not enable read notifications on TCP in bind()

In bind+connect scenario, rejected connection can trigger a read
notification while the socket is opened. But unlike UDP, reading from
the socket engine or emitting a readyRead() signal is not allowed for
the TCP socket in bound or connecting state.

To make a bind+connect scenario work properly, disable the read
notifications until a connection is established.

Task-number: QTBUG-50124
Change-Id: I7b3d015b0f6021fb9ff9f83560478aa5545f41f5
Reviewed-by: Richard J. Moore <rich@kde.org>

src/network/socket/qabstractsocket.cpp

@@ -1530,7 +1530,8 @@ bool QAbstractSocketPrivate::bind(const QHostAddress &address, quint16 port, QAb
     localPort = socketEngine->localPort();
 
     emit q->stateChanged(state);
-    socketEngine->setReadNotificationEnabled(true);
+    if (socketType == QAbstractSocket::UdpSocket)
+        socketEngine->setReadNotificationEnabled(true);
     return true;
 }
 

tests/auto/network/socket/qtcpsocket/tst_qtcpsocket.cpp

@@ -200,6 +200,7 @@ private slots:
 
     void setSocketOption();
     void clientSendDataOnDelayedDisconnect();
+    void readNotificationsAfterBind();
 
 protected slots:
     void nonBlockingIMAP_hostFound();
@@ -2984,5 +2985,25 @@ void tst_QTcpSocket::clientSendDataOnDelayedDisconnect()
     delete socket;
 }
 
+// Test that the socket does not enable the read notifications in bind()
+void tst_QTcpSocket::readNotificationsAfterBind()
+{
+    QFETCH_GLOBAL(bool, setProxy);
+    if (setProxy)
+        return;
+
+    QAbstractSocket socket(QAbstractSocket::TcpSocket, Q_NULLPTR);
+    QVERIFY2(socket.bind(), "Bind error!");
+
+    connect(&socket, SIGNAL(error(QAbstractSocket::SocketError)), &QTestEventLoop::instance(), SLOT(exitLoop()));
+    QSignalSpy spyReadyRead(&socket, SIGNAL(readyRead()));
+    socket.connectToHost(QtNetworkSettings::serverName(), 12346);
+
+    QTestEventLoop::instance().enterLoop(10);
+    QVERIFY2(!QTestEventLoop::instance().timeout(), "Connection to closed port timed out instead of refusing, something is wrong");
+    QVERIFY2(socket.state() == QAbstractSocket::UnconnectedState, "Socket connected unexpectedly!");
+    QCOMPARE(spyReadyRead.count(), 0);
+}
+
 QTEST_MAIN(tst_QTcpSocket)
 #include "tst_qtcpsocket.moc"