A QAbstractSocket can be close()'d at any time, independently of its current connection state. being closed means that we cannot use it to read or write data, but internally it might still have some data to send or receive, for example to an http server. We can even get a connected() signal after close()'ing the socket. We need to catch this condition and mark any pending data not yet written to the socket for resending. (cherry picked from commit 0df5d079290b4c3b13e58e9397fabdc1dfdba96b) Task-number: QTBUG-48326 Change-Id: I67d9ad36f7288c9c6bef51aa6253d7b187737601 Reviewed-by: Ulf Hermann <ulf.hermann@theqtcompany.com> Reviewed-by: Markus Goetz (Woboq GmbH) <markus@woboq.com>