Invalid address specified to RtlValidateHeap in cross-dll application when using QTcpSocket - c++

Question

Background:
Sorry this is such a complex problem but it is driving me nuts. Finding a solution may help others who need a compartmentalized application.
I have a Qt program that is VERY compartmentalized because it is meant to host plugins and be used in a variety of situations, sometimes as a server, sometimes as a client, sometimes as both. The plugins that are loaded are login dependent. (Because the access defined for the user is not necessarily up to the user and the user's access to data and functionality may be limited).
The application relies on a core DLL library (specific to the application) which is used by the main exe, the client, the server, and all plugin dlls. Client and server functionality are also in separate dlls. I am new to this style of programming so that may be leading to my issue.
My Problem:
I have a class called "BidirectionalTcpConnection" that is defined in the core DLL which is to be used by the executable, the client dll, and the server dll. It is a class that keeps track of data that is passed back and forth over a QTcpSocket. I wrote the class to avoid THE SAME problem as I am having now except that the problem originally occurred while using the QTcpSocket.ReadAll() function AND in the current situation. (If I tried reading all but the last byte, and then read the last byte using the QTcpSocket.peek(...) function it would work fine).
My new class successfully reads from and writes to the socket without error but when I try and close or abort the socket (this happened with my earlier workaround too...), I get the same error I was getting when I tried to read it (only on the last byte). I get an Invalid address specified to RtlValidateHeap. Basically it throws a "User Breakpoint" in dbgheap.c
My Hypothesis (What I believe is wrong):
The dbgheap.c documents that it is checking to see if the address is valid and that it resides on the current heap.
It is possible that the need for compartmentalizing my application may be leading to this issue. The data being supplied to the socket for sending was originally being allocated in the executable's heap along with the instance of BidirectionalTcpConnection. (I am trying to send the login and receive the permissions for application access). The socket itself however is being allocated in the core heap (assuming that the dll has a separate heap from the exe for internal data). I tried avoiding this by doing a deep copy of each piece of data that is to be sent over the socket within the core dll code. But that hasn't solved the problem. Presumably because the BidirectionalTcpConnection is still being allocated on a separate heap from the socket itself.
My question(s) for anyone who can help:
Is the assumption in my hypothesis correct?
Do I need to allocate the socket and the connection on the same heap? How do I
overcome this issue?
Also... if you look at the code, will I need to delete the returned
string that needs to be processed by the executable within the core
dll in order to avoid the same issue?
If you guys need some code... I have supplied what I think is necessary. I can supply more upon request.
Some Code:
For starters.. here is some basic code to show the way things are allocated. The login is performed in main before the main interface is shown. w is the main interface window class instance. Here is the code that starts the process leading to the crash:
while (loginFailed)
{
splash->showLogin();
while (splash->isWaitingOnLogin())
a.processEvents();
QString username(*splash->getUserName());
QString password(*splash->getPassword());
// LATER: encrypt login for sending
loginFailed = w.loginFailed(username, password, a);
}
Here is the code that instantiates the BidirectionalTcpConnection on the executable's stack and sends the login data. This code is inside a few separate private methods of the Qt main window class.
// method A
// processes Qstring parameters into sendable data...
// then calls method B
// which creates the instance of *BidirectionalTcpConnection*
...
if (getServerAddress() == QString("LOCAL"))
mTcpConnection = new BidirectionalTcpConnection(getHostAddressIn()->toString(),
(quint16)ServerPorts::loginRequest, (long)15, this);
else
mTcpConnection = new BidirectionalTcpConnection(*getServerAddress(),
(quint16)ServerPorts::loginRequest, (long)15, this);
...
// back to method A...
mTcpConnection->sendBinaryData(*dataStream);
mTcpConnection->flushMessages(); // sends the data across the socket
...
// waits for response and then parses user data when it comes
while (waitForResponse)
{
if (mTcpConnection->hasBufferedMessages())
{
QString* loginXML = loginConnection->getNextMessageAsText();
// parse the xml
if (parseLogin(*loginXML))
{
waitForResponse = false;
}
...
}
}
...
// calls method that closes the socket which causes crash
mTcpConnection->abortConnection(); // crash occurs inside this method
delete mTcpConnection;
mTcpConnection = NULL;
Here is the relevant BidirectionalTcpConnection code in order of use. Note, this code is located in the core dll so presumably it is allocating data on a separate stack...
BidirectionalTcpConnection::BidirectionalTcpConnection(const QString& destination,
quint16 port, long timeOutInterval, TimeUnit unit, QObject* parent) :
QObject(parent),
mSocket(parent),
...
{ }
void BidirectionalTcpConnection::sendBinaryData(QByteArray& data)
{
// notice I try and avoid different heaps where I can by copying the data...
mOutgoingMessageQueue.enqueue(new QByteArray(data)); // member is of QQueue type
}
QString* BidirectionalTcpConnection::getNextMessageAsText()
// NOTE: somehow I need to delete the returned pointer to prevent memory leak
{
if (mIncomingMessageQueue.size() == 0)
return NULL;
else
{
QByteArray* data = mIncomingMessageQueue.dequeue();
QString* stringData = new QString(*data);
delete data;
return stringData;
}
}
void BidirectionalTcpConnection::abortConnection()
{
mSocket.abort(); // **THIS CAUSES ERROR/CRASH**
clearQueues();
mIsConnected = false;
}