QSslSocket: Don't call 'transmit' in unencrypted mode

At the same time I'll add a generic protection against being called in
unprotected mode in the schannel backend (openssl already has it in a
different form).

Pick-to: 5.15 6.0
Change-Id: I97c1be6239c27e306de0af7ad568fbcfde09da71
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

2 files changed, 4 insertions, 1 deletions

diff --git a/src/network/ssl/qsslsocket.cpp b/src/network/ssl/qsslsocket.cpp
index c5444b139e..a7c6b16b19 100644
--- a/src/network/ssl/qsslsocket.cpp
+++ b/src/network/ssl/qsslsocket.cpp
@@ -2326,7 +2326,7 @@ void QSslSocketPrivate::_q_errorSlot(QAbstractSocket::SocketError error)
     qCDebug(lcSsl) << "\terrorString =" << q->errorString();
 #endif
     // this moves encrypted bytes from plain socket into our buffer
-    if (plainSocket->bytesAvailable()) {
+    if (plainSocket->bytesAvailable() && mode != QSslSocket::UnencryptedMode) {
         qint64 tmpReadBufferMaxSize = readBufferMaxSize;
         readBufferMaxSize = 0; // reset temporarily so the plain sockets completely drained drained
         transmit();
diff --git a/src/network/ssl/qsslsocket_schannel.cpp b/src/network/ssl/qsslsocket_schannel.cpp
index 051eb3fc3f..1c482f56d7 100644
--- a/src/network/ssl/qsslsocket_schannel.cpp
+++ b/src/network/ssl/qsslsocket_schannel.cpp
@@ -1325,6 +1325,9 @@ void QSslSocketBackendPrivate::transmit()
 {
     Q_Q(QSslSocket);
 
+    if (mode == QSslSocket::UnencryptedMode)
+        return; // This function should not have been called
+
     // Can happen if called through QSslSocket::abort->QSslSocket::close->QSslSocket::flush->here
     if (plainSocket->state() == QAbstractSocket::SocketState::UnconnectedState)
         return;