QNAM: Fix reply deadlocks on server closing connection

The _q_readyRead can also be called from readMoreLater() because we implemented
it so that bandwidth limited reading can be implemented.
This can lead to a race condition if the socket is closing at the specific moment
and then deadlock the channel: It will stay unusable with a zombie request.
The fix in QHttpProtocolaHandler checks if there is actually bytes available to read
from the socket and only then continue.

The fix in the HTTP channel needs to be done to properly finish the reply in
cases of a server replying with HTTP/1.0 or "Connection: close".
The delayed incovation of _q_receiveReply will properly finish up the reply.

Change-Id: I19ce2ae595f91d56386cc7406ccacc9935672b6b
Reviewed-by: Richard J. Moore <rich@kde.org>

2 files changed, 10 insertions, 1 deletions

diff --git a/src/network/access/qhttpnetworkconnectionchannel.cpp b/src/network/access/qhttpnetworkconnectionchannel.cpp
index 7428f9bf5b..257aa13718 100644
--- a/src/network/access/qhttpnetworkconnectionchannel.cpp
+++ b/src/network/access/qhttpnetworkconnectionchannel.cpp
@@ -829,11 +829,15 @@ void QHttpNetworkConnectionChannel::_q_error(QAbstractSocket::SocketError socket
 
             if (!reply->d_func()->expectContent()) {
                 // No content expected, this is a valid way to have the connection closed by the server
+                // We need to invoke this asynchronously to make sure the state() of the socket is on QAbstractSocket::UnconnectedState
+                QMetaObject::invokeMethod(this, "_q_receiveReply", Qt::QueuedConnection);
                 return;
             }
             if (reply->contentLength() == -1 && !reply->d_func()->isChunked()) {
                 // There was no content-length header and it's not chunked encoding,
                 // so this is a valid way to have the connection closed by the server
+                // We need to invoke this asynchronously to make sure the state() of the socket is on QAbstractSocket::UnconnectedState
+                QMetaObject::invokeMethod(this, "_q_receiveReply", Qt::QueuedConnection);
                 return;
             }
             // ok, we got a disconnect even though we did not expect it
diff --git a/src/network/access/qhttpprotocolhandler.cpp b/src/network/access/qhttpprotocolhandler.cpp
index ab2e3dac57..a2083158f1 100644
--- a/src/network/access/qhttpprotocolhandler.cpp
+++ b/src/network/access/qhttpprotocolhandler.cpp
@@ -237,7 +237,12 @@ void QHttpProtocolHandler::_q_readyRead()
     }
 
     if (m_channel->isSocketWaiting() || m_channel->isSocketReading()) {
-        m_channel->state = QHttpNetworkConnectionChannel::ReadingState;
+        if (m_socket->bytesAvailable()) {
+            // We might get a spurious call from readMoreLater()
+            // call of the QHttpNetworkConnection even while the socket is disconnecting.
+            // Therefore check if there is actually bytes available before changing the channel state.
+            m_channel->state = QHttpNetworkConnectionChannel::ReadingState;
+        }
         if (m_reply)
             _q_receiveReply();
     }