QNAM: Fix upload corruptions when server closes connection

This patch fixes several upload corruptions if the server closes the connection
while/before we send data into it. They happen inside multiple places in the HTTP
layer and are explained in the comments.
Corruptions are:
* The upload byte device has an in-flight signal with pending upload data, if
it gets reset (because server closes the connection) then the re-send of the
request was sometimes taking this stale in-flight pending upload data.
* Because some signals were DirectConnection and some were QueuedConnection, there
was a chance that a direct signal overtakes a queued signal. The state machine
then sent data down the socket which was buffered there (and sent later) although
it did not match the current state of the state machine when it was actually sent.
* A socket was seen as being able to have requests sent even though it was not
encrypted yet. This relates to the previous corruption where data is stored inside
the socket's buffer and then sent later.

The included auto test produces all fixed corruptions, I detected no regressions
via the other tests.
This code also adds a bit of sanity checking to protect from possible further
problems.

[ChangeLog][QtNetwork] Fix HTTP(s) upload corruption when server closes connection

Change-Id: I54c883925ec897050941498f139c4b523030432e
Reviewed-by: Peter Hartmann <peter-qt@hartmann.tk>

1 files changed, 29 insertions, 7 deletions

diff --git a/src/network/access/qhttpthreaddelegate_p.h b/src/network/access/qhttpthreaddelegate_p.h
index 16610828cb..b553409391 100644
--- a/src/network/access/qhttpthreaddelegate_p.h
+++ b/src/network/access/qhttpthreaddelegate_p.h
@@ -187,6 +187,7 @@ protected:
     QByteArray m_dataArray;
     bool m_atEnd;
     qint64 m_size;
+    qint64 m_pos; // to match calls of haveDataSlot with the expected position
 public:
     QNonContiguousByteDeviceThreadForwardImpl(bool aE, qint64 s)
         : QNonContiguousByteDevice(),
@@ -194,7 +195,8 @@ public:
           m_amount(0),
           m_data(0),
           m_atEnd(aE),
-          m_size(s)
+          m_size(s),
+          m_pos(0)
     {
     }
 
@@ -202,6 +204,11 @@ public:
     {
     }
 
+    qint64 pos() Q_DECL_OVERRIDE
+    {
+        return m_pos;
+    }
+
     const char* readPointer(qint64 maximumLength, qint64 &len)
     {
         if (m_amount > 0) {
@@ -229,11 +236,10 @@ public:
 
         m_amount -= a;
         m_data += a;
+        m_pos += a;
 
-        // To main thread to inform about our state
-        emit processedData(a);
-
-        // FIXME possible optimization, already ask user thread for some data
+        // To main thread to inform about our state. The m_pos will be sent as a sanity check.
+        emit processedData(m_pos, a);
 
         return true;
     }
@@ -250,10 +256,21 @@ public:
     {
         m_amount = 0;
         m_data = 0;
+        m_dataArray.clear();
+
+        if (wantDataPending) {
+            // had requested the user thread to send some data (only 1 in-flight at any moment)
+            wantDataPending = false;
+        }
 
         // Communicate as BlockingQueuedConnection
         bool b = false;
         emit resetData(&b);
+        if (b) {
+            // the reset succeeded, we're at pos 0 again
+            m_pos = 0;
+            // the HTTP code will anyway abort the request if !b.
+        }
         return b;
     }
 
@@ -264,8 +281,13 @@ public:
 
 public slots:
     // From user thread:
-    void haveDataSlot(QByteArray dataArray, bool dataAtEnd, qint64 dataSize)
+    void haveDataSlot(qint64 pos, QByteArray dataArray, bool dataAtEnd, qint64 dataSize)
     {
+        if (pos != m_pos) {
+            // Sometimes when re-sending a request in the qhttpnetwork* layer there is a pending haveData from the
+            // user thread on the way to us. We need to ignore it since it is the data for the wrong(later) chunk.
+            return;
+        }
         wantDataPending = false;
 
         m_dataArray = dataArray;
@@ -285,7 +307,7 @@ signals:
 
     // to main thread:
     void wantData(qint64);
-    void processedData(qint64);
+    void processedData(qint64 pos, qint64 amount);
     void resetData(bool *b);
 };