After a lot of TCP fighting...

Have you looked at GetLastError() after the failure?

Have you looked at the winsock errors? WSA_WAIT_TIMEOUT etc?

After the failure run netstat and see what the connection state is.

Make sure you read this article and understand what state your socket is being left in:

http://tangentsoft.net/wskfaq/articles/debugging-tcp.html

HTH,

ahoodin

PS Additionally how are you ascertaining packet length on the client after you send the string back to it? Can you post a .zip with the client and server code?

This is an error on your server.

Your server is resetting the connection.

This could happen because your socket listener/server is having an exception.

Also this could happen if your trying to send data and the server is not accepting it anymore. Your Client and server may be out of sync.

With Microsoft, every packet has to be ACKed. ( Look at the state diagram in the link I forwarded you). Get a packet sniffer and sniff around to learn more.

The client send()s out some data, and then the server recv()s that data and send()s some data to the client which recv()s that data. The client has to recv all the data before it moves on, so you have to have some scheme for the client to know how many times to call recv()/how much data to recv(). If you didn't write the client you are probably using an echo client which is expecting the same amount of data you just sent to the server back from the server.

You have to write a custom client.

HTH,

ahoodin

PS If this helps dont forget to rate!

You will need to bind() to the socket, set the socket to listen() and then accept() incoming connections:

if (bind(servSock,(struct sockaddr *)&ServAddr,sizeof(ServAddr)) < 0)
DieWithError("bind() failed");

if (listen(servSock,MAXPENDING) < 0 )
DieWithError("listen() failed");

for (;;)
{
clntLen = sizeof(ClntAddr);

if ((clntSock = accept(servSock, (struct sockaddr*) &ClntAddr, (int*)&clntLen)) < 0)
DieWithError("accept() failed.");

HandleClient(clntSock);

}
}
void HandleClient(int clntSock)
{
char echoBuffer[RCVBUFSIZE];
int rcvMsgSize=0,totrcv=0;
if ((rcvMsgSize = recv(clntSock, echoBuffer, RCVBUFSIZE, 0)) < 0)
DieWithError("recv() failed.");
totrcv=rcvMsgSize;
while (rcvMsgSize > 0)
{
if (send(clntSock, echoBuffer, rcvMsgSize, 0) != rcvMsgSize)
DieWithError("Send() failed");

if ((rcvMsgSize = recv(clntSock, echoBuffer, RCVBUFSIZE,0)) < 0)
DieWithError("recv() failed");
totrcv+=rcvMsgSize;
}
closesocket(clntSock);
}

Check the parameters.

What port is your server on?

What does GetLastError() tell you?

What OS?

Please post your server code.

ahoodin

Ok.
System: Windows XP

Complete client Thread:

DWORD WINAPI tcpThread::clientthread_run(LPVOID lparam)
{

const int kBufferSize=1024;
const char* kpcEchoMessage = "This is a test of the emergency data "
"transfer system. If this had been real a real emergency, we "
"would have sent this data out-of-band.";
const int kEchoMessageLen = strlen(kpcEchoMessage);
const int kShutdownDelay = 3;

//Client socket locale
sockaddr_in localSock;
localSock.sin_family=AF_INET; //Address family
localSock.sin_addr.s_addr=inet_addr("127.0.0.1"); //IP address
localSock.sin_port=htons((u_short)2003); //port to use

//Connessione al server
sockaddr_in* addr=(sockaddr_in*) lparam;
SOCKET clientSock=socket(AF_INET, SOCK_STREAM, 0);

if (clientSock==INVALID_SOCKET) {MessageBox(NULL,"Creazione socket:una merda","Oh!",MB_OK);}

if (connect(clientSock, (sockaddr*)&localSock, sizeof(sockaddr_in)) == SOCKET_ERROR) {
clientSock = INVALID_SOCKET;
MessageBox(NULL,"Socket rancido nel client","Oh!",MB_OK);

}
//-------

//Manda stringa al server
if (send(clientSock, kpcEchoMessage, kEchoMessageLen, 0) == SOCKET_ERROR) {

MessageBox(NULL,"Spedizione andata a male", "De'",MB_OK);

int error=WSAGetLastError();

switch (WSAGetLastError())
{
case WSANOTINITIALISED:
MessageBox(NULL,"A successful WSAStartup must occur before using this function","Oh!",MB_OK);
break;
case WSAENETDOWN:
MessageBox(NULL,"The network subsystem has failed","Oh!",MB_OK);
break;
case WSAEADDRINUSE:
MessageBox(NULL,"The specified address is already in use","Oh!",MB_OK);
break;
case WSAEINTR:
MessageBox(NULL,"The (blocking) call was canceled through WSACancelBlockingCall","Oh!",MB_OK);
break;
case WSAEINPROGRESS:
MessageBox(NULL,"A blocking Windows Sockets 1.1 call is in progress, or the service provider is still processing a callback function","Oh!",MB_OK);
break;
case WSAEALREADY:
MessageBox(NULL,"A nonblocking connect call is in progress on the specified socket","Oh!",MB_OK);
break;
case WSAEADDRNOTAVAIL:
MessageBox(NULL,"The specified address is not available from the local machine","Oh!",MB_OK);
break;
case WSAEAFNOSUPPORT:
MessageBox(NULL,"Addresses in the specified family cannot be used with this socket","Oh!",MB_OK);
break;
case WSAECONNREFUSED:
MessageBox(NULL,"The attempt to connect was forcefully rejected","Oh!",MB_OK);
break;
case WSAEFAULT:
MessageBox(NULL,"The name or the namelen argument is not a valid part of the user address space, the namelen argument is too small, or the name argument contains incorrect address format for the associated address family","Oh!",MB_OK);
break;
case WSAEINVAL:
MessageBox(NULL,"The parameter s is a listening socket, or the destination address specified is not consistent with that of the constrained group the socket belongs to","Oh!",MB_OK);
break;
case WSAEISCONN:
MessageBox(NULL,"The socket is already connected (connection-oriented sockets only)","Oh!",MB_OK);
break;
case WSAENETUNREACH:
MessageBox(NULL,"The network cannot be reached from this host at this time","Oh!",MB_OK);
break;
case WSAENOBUFS:
MessageBox(NULL,"No buffer space is available. The socket cannot be connected","Oh!",MB_OK);
break;
case WSAENOTSOCK:
MessageBox(NULL,"The descriptor is not a socket","Oh!",MB_OK);
break;
case WSAETIMEDOUT:
MessageBox(NULL,"Attempt to connect timed out without establishing a connection","Oh!",MB_OK);
break;
case WSAEWOULDBLOCK:
MessageBox(NULL,"The socket is marked as nonblocking and the connection cannot be completed immediately. It is possible to select the socket while it is connecting by selecting it for writing","Oh!",MB_OK);
break;
case WSAEACCES:
MessageBox(NULL,"Attempt to connect datagram socket to broadcast address failed because setsockopt SO_BROADCAST is not enabled","Oh!",MB_OK);
break;
}
}
//--------

//Ricevi risposta dal server
char acReadBuffer[kBufferSize];
int nTotalBytes = 0;

while (nTotalBytes < kEchoMessageLen) {

int nNewBytes = recv(clientSock, acReadBuffer + nTotalBytes,kBufferSize - nTotalBytes, 0);
if (nNewBytes == SOCKET_ERROR) {
return -1;
}

else if (nNewBytes == 0) {

MessageBox(NULL,"Connessione resettata dal piiir","Oh",MB_OK);
}

nTotalBytes += nNewBytes;
}

//Qui si controlla che i dati siano tutti a posto
if (strncmp(acReadBuffer, kpcEchoMessage, nTotalBytes) == 0) {
MessageBox(NULL,"Risposta ok!","Oh!",MB_OK);
}

else {
MessageBox(NULL,"Qualcosa nei dati si e' sbombolato", "Oh!",MB_OK);
}

//--------

//Controllo errori vari
int nBytes;
if (nTotalBytes>0) {

if (nTotalBytes==kBufferSize) {

MessageBox(NULL,"Qualche troiaio, forse overflow", "Oh!",MB_OK);
}

} else if (nTotalBytes==0) {

MessageBox(NULL,"Connessione chiusa a cavolo","Oh!",MB_OK);

} else {

MessageBox(NULL,"Altri errori scassanti","Oh!",MB_OK);

}

}

There's an init() function eslsewhere calling WSADATA and all its initialization, so that's not the error.

I followed the tangentsoft basic server/client example as a blueprint for my frankensteinware.

set your port correctly in this line.
localSock.sin_port=htons((u_short)2003); //port to use
That was the first problem I found.

I was able to connect with the code you sent me.

Also, I can connect with the sockaddr_in structure declared inside the thread, but the old error strikes back when I pass a &sockaddr_in param to the client thread. Any suggestion?
Thanks.

Yes ZillionDollaSadist!

After your client sends the data and recieve all the data you expect on the client, you must close your socket.

It worked for me! I was able to send the data and close the socket gracefully/consistantly.

It's all working now! Wow!
I close with shutdown and then closesocket. And following connections are all fine.

You will need to come up with a scheme to get your own client and server to work. How will my server know how many bytes to receive. What will it send back, how will my client know how many bytes were received successfully? Etc.
Otherwise your just making an echoserver.

The stuff I sent in fact was just a skeleton I have to build upon now. I'll have to decide something about packets now, right? :)
Thanks a lot.

Nevermind my last message, I figured it out by myself. Wow.