Ricardo Vazquez
2007-03-01 12:27:26 UTC
Hi everyone!
Something weird is happening with an application of mine:
It works OK on any computer but on one (I have nearly one hundred
installations made, up and running).
The computer on which it is not running is: WinXP professional 2002 SP2 on
AMD Athlon64
Mainly my app is a TCP server.
Each client has a listening thread with a loop and a call to the platform
SDK Windows sockets blocking (synchronous) "recv" function
(http://msdn2.microsoft.com/en-us/library/ms740121.aspx) -code below.
According to MS documentation when function "recv" returns SOCKET_ERROR
(-1), an error can be therefore retrieved with WSAGetLastError.
As you can see, I check WSAGetLastError immediately after returning recv.
This works perfectly in every computer.
But on this very one computer out of 100, several times a day, "recv"
returns SOCKET_ERROR (-1), BUT WSAGetLastError returns 0 (!!!)
Sniffing the TCP traffic via Ethereal software I can see that, in fact, the
TCP connection is still up: so it is the "recv" function that is telling me
a lie.
Has this happened to anyone out there?
Have you find any Windows or Athlon64 known bug regarding this matter
(recv=-1 but WSAGetLastError=0)?
Can you think of a way to make my application work on this problematic
computer?
Thank you very much!
Ricardo Vázquez.
Madrid, Spain.
--------------- CODE ---------------
int CClientThread::Run()
{
char msg[maxLen];
while (!bExit) {
int nRet = recv(clientSocket, msg, maxLen, 0);
if (nRet == SOCKET_ERROR && bExit) {
// Stop closes clientSocket on exit. WSAETIMEDOUT
err.Format("Stop closes clientSocket on exit");
g_logSystem.logWarning(0, err);
break;
}
else if (nRet == SOCKET_ERROR)
{
int nErr = WSAGetLastError();
if (nErr == 0)
{
err.Format("recv=-1 but WSAGetLastError=0 from client %s on socket
%ld.", clientId, clientSocket);
g_logSystem.logWarning(0, err);
continue;
}
else
{
err.Format("Connection lost with client %s on socket %ld. Error code
%ld: recv() = SOCKET_ERROR", clientId, clientSocket, nErr);
g_logSystem.logWarning(0, err);
closesocket(clientSocket);
server->DeleteClient(clientSocket);
cti_RemoveEventListener(this);
return SOCKET_ERROR;
}
}
else if (!nRet) {
// Connection has been gracefully closed.
err.Format("Client %s with socket %ld has closed the connection: recv() =
0 (apparently)", clientId, clientSocket);
g_logSystem.logNormal(0, err);
closesocket(clientSocket);
server->DeleteClient(clientSocket);
cti_RemoveEventListener(this);
return 0;
}
else {
// Proccess message:
msg[nRet] = 0x0;
err.Format("[Cli %ld] Received: %s", clientSocket, msg);
g_logSystem.logNormal(4, err);
CString sMensaje;
sMensaje = CStrTok(msg, "%");
while (!sMensaje.IsEmpty())
{
parse(sMensaje);
sMensaje = CStrTok("", "%");
}
}
}
return 0;
}
Something weird is happening with an application of mine:
It works OK on any computer but on one (I have nearly one hundred
installations made, up and running).
The computer on which it is not running is: WinXP professional 2002 SP2 on
AMD Athlon64
Mainly my app is a TCP server.
Each client has a listening thread with a loop and a call to the platform
SDK Windows sockets blocking (synchronous) "recv" function
(http://msdn2.microsoft.com/en-us/library/ms740121.aspx) -code below.
According to MS documentation when function "recv" returns SOCKET_ERROR
(-1), an error can be therefore retrieved with WSAGetLastError.
As you can see, I check WSAGetLastError immediately after returning recv.
This works perfectly in every computer.
But on this very one computer out of 100, several times a day, "recv"
returns SOCKET_ERROR (-1), BUT WSAGetLastError returns 0 (!!!)
Sniffing the TCP traffic via Ethereal software I can see that, in fact, the
TCP connection is still up: so it is the "recv" function that is telling me
a lie.
Has this happened to anyone out there?
Have you find any Windows or Athlon64 known bug regarding this matter
(recv=-1 but WSAGetLastError=0)?
Can you think of a way to make my application work on this problematic
computer?
Thank you very much!
Ricardo Vázquez.
Madrid, Spain.
--------------- CODE ---------------
int CClientThread::Run()
{
char msg[maxLen];
while (!bExit) {
int nRet = recv(clientSocket, msg, maxLen, 0);
if (nRet == SOCKET_ERROR && bExit) {
// Stop closes clientSocket on exit. WSAETIMEDOUT
err.Format("Stop closes clientSocket on exit");
g_logSystem.logWarning(0, err);
break;
}
else if (nRet == SOCKET_ERROR)
{
int nErr = WSAGetLastError();
if (nErr == 0)
{
err.Format("recv=-1 but WSAGetLastError=0 from client %s on socket
%ld.", clientId, clientSocket);
g_logSystem.logWarning(0, err);
continue;
}
else
{
err.Format("Connection lost with client %s on socket %ld. Error code
%ld: recv() = SOCKET_ERROR", clientId, clientSocket, nErr);
g_logSystem.logWarning(0, err);
closesocket(clientSocket);
server->DeleteClient(clientSocket);
cti_RemoveEventListener(this);
return SOCKET_ERROR;
}
}
else if (!nRet) {
// Connection has been gracefully closed.
err.Format("Client %s with socket %ld has closed the connection: recv() =
0 (apparently)", clientId, clientSocket);
g_logSystem.logNormal(0, err);
closesocket(clientSocket);
server->DeleteClient(clientSocket);
cti_RemoveEventListener(this);
return 0;
}
else {
// Proccess message:
msg[nRet] = 0x0;
err.Format("[Cli %ld] Received: %s", clientSocket, msg);
g_logSystem.logNormal(4, err);
CString sMensaje;
sMensaje = CStrTok(msg, "%");
while (!sMensaje.IsEmpty())
{
parse(sMensaje);
sMensaje = CStrTok("", "%");
}
}
}
return 0;
}