C++ Socket recv() reads the same string twice (WinSock2) - c++

Question

I'm working on creating a maze game, where two players connect (one acts as host, the other the player). In this, I'm sending XML data as a string using the send() function. (I'm also using a pre-made Socket class, keeping in mind this is for non-profit activities, meaning it doesn't break the copyright.) Keep in mind the client & server are running on Windows 7 using the WinSock2.h package.
The problem I'm encountering is fairly straightforward. I first send the Maze XML file, this reads properly and is able to save the maze in a series of tiles. After this, another XML file is sent, updating the position of the player (and enemy) of the other user's game. However, when I attempt to READ this line, it starts reading from the beginning of the buffer, and it seems as if the buffer isn't being cleared because it starts reading the Maze XML file again.
Is there a way to clear the buffer that recv() uses? I can't think of any other reason why the Maze XML is being read twice, when it isn't being sent twice.
Below is the code that receives the XML, character by character. This is the server's code, the client code just reverses the order of sending/receiving the data. Not sure if that's necessary or relevant.
[code]
while (1) { char r;
switch(recv(s_, &r, 1, 0)) {
case 0: // not connected anymore;
// ... but last line sent
// might not end in \n,
// so return ret anyway.
return ret;
case -1:
return "";
// if (errno == EAGAIN) {
// return ret;
// } else {
// // not connected anymore
// return "";
// }
}
ret += r;
if (r == '<') {
counter = 0;
check = "";
}
check += r;
if (counter == 6 && check.compare(ender) == 0)
{
return ret;
}
//if (r == '\n') return ret;
counter++;
}
[/code]
And this is the code that sends/receives the different XML files.
[code]
Socket* s=in.Accept();
cout << "Accepted a Call from a Client." << endl;
// Here is where we receive the first (Maze) XML File, and
// send our maze as XML
string mazeS = s->ReceiveLineMaze();
TiXmlDocument testDoc;
testDoc.Parse(mazeS.c_str(), 0, TIXML_ENCODING_UTF8);
testDoc.SaveFile("ServerTestDoc.xml");
//testDoc.SaveFile("testXMLFromString.xml");
Tile** theirMaze = readXML(testDoc);
TiXmlDocument theMaze = maze->mazeToXML();
//theMaze.SaveFile("ClientTestWrite.XML");
TiXmlPrinter printer;
theMaze.Accept(&printer);
string toSend = printer.CStr();
cout << toSend << endl;
s->SendLine(toSend);
//RENDER STUFF IN THIS LOOP
bool inOurMaze = false;
while(boolValues->running) {
// This next line is where I want to receive the update on position
// but instead it reads the Maze XML file again, the one I read up
// above
string posReceive = s->ReceiveLineUpdate();
TiXmlDocument theirPos;
theirPos.Parse(posReceive.c_str(), 0, TIXML_ENCODING_UTF8);
... This is where I process the update XML ...
TiXmlDocument updatePos = maze->updatePositionXML();
TiXmlPrinter printerPos;
updatePos.Accept(&printerPos);
string posSend = printer.CStr();
s->SendLine(posSend);
[/code]
Any help is appreciated. If it isn't clear up top, let me summarize.
I first swap an XML file that details the Maze itself. This works fine. Then I attempt to swap the update XML files, that update the player/enemy positions for the other user. But when I attempt to use recv(...), it starts to read the Maze file again, NOT the update file. It's...perplexing.
Oh, and here's the send code (very simple):
[code]
s += '\n';
send(s_,s.c_str(),s.length(),0);
[/code]
where s_ is the socket and s.c_str is the string that needs to be sent (in this case the different XML files).

Answer 1

As #Martin points out, the issue is definitely with the code. Few things to check, looks like the data is read into the buffer "ret" and that's under your control. Is that getting flushed / cleared each time (the code does not make that clear). If this is fine, check the client code to ensure that the data is sent correctly.
Best option is to debug thru your send and receive functions in the IDE, you should be able to spot whats wrong.