Thread: WaitNamedPipe() Issue

Hi...

I'm trying to send a message to a server using a named pipe. I managed to send a message from the client application to the server application in the same machine. But when i try sending the message with the server application in another machine it returns false in the WaitNamedPipe() function

I have turned off both machines firewall, i can ping both machines and the ip address of the server is correct.

What can be the problem?
Here is the code for my Cliente and Server App:

CLIENT

Code:

int main(int argc, char* argv[])
{
    HANDLE hPipe;
    DWORD dwReadWritten;
	DWORD dwMode=PIPE_READMODE_MESSAGE|PIPE_WAIT;
	char buffer[1024];
    char *pszPipe="\\\\192.168.1.82\\pipe\\ServNT";

    if (!WaitNamedPipe(pszPipe, NMPWAIT_WAIT_FOREVER)) 
	{
		printf("CLIENT: Error connecting\n");
		return 1;
	}
	printf("CLIENT: Connect to server\n");
    hPipe = CreateFile(pszPipe, GENERIC_WRITE|GENERIC_READ, 0, NULL,
                       OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
	if (hPipe==NULL) 
	{
		printf("CLIENT: Error a connecting \n");
		return 1;
	}
	if (!SetNamedPipeHandleState(hPipe,&dwMode,NULL,NULL)) 
	{
		printf("CLIENT: Error SetNamedPipeHandleState\n");
		return 1;
	}
	while (1) 
	{
		printf("Frase: ");
		gets_s(buffer,1024);
		buffer[lstrlen(buffer)]=0;
		if (!strncmp(buffer,"end",3))
			break;
		/*if (!WriteFile(hPipe, buffer, strlen(buffer)+1,
									  &dwReadWritten, NULL)) {
			printf("CLIENT: Error WriteFile\n");
			return 1;
		}
		if (!ReadFile(hPipe, buffer, 1024,
									  &dwReadWritten, NULL)) {
			printf("CLIENT: Error  ReadFile%d\n",GetLastError());
			return 1;
		}*/
		if (!TransactNamedPipe(hPipe, buffer, lstrlen(buffer)+1,
									  buffer, 1024,
									  &dwReadWritten, NULL)) {
			printf("CLIENT: Error WriteFile\n");
			return 1;
		}
		printf("\nResponse: %s\n",buffer);
	}
	printf("CLIENT: turn off pipe\n");
	CloseHandle(hPipe);
	return 0;
}

SERVER

Code:

void main( ) 
{ 
    SERVICE_TABLE_ENTRY   DispatchTable[] = 
    { 
        { NOME_DO_SERVICO, MyServiceStart      }, 
        { NULL,              NULL          } 
    }; 
 
    if (!StartServiceCtrlDispatcher( DispatchTable)) 
    { 
        ShowError(" [ServNT] StartServiceCtrlDispatcher error = %d\n", GetLastError()); 
    } 
} 

void WINAPI MyServiceStart (DWORD argc, LPTSTR *argv) 
{
	HANDLE hPipe;
	OVERLAPPED ovl;

    MyServiceStatus.dwServiceType        = SERVICE_WIN32; 
    MyServiceStatus.dwCurrentState       = SERVICE_START_PENDING; 
    MyServiceStatus.dwControlsAccepted   = 0;
	MyServiceStatus.dwWin32ExitCode      = 0; 
    MyServiceStatus.dwServiceSpecificExitCode = 0; 
    MyServiceStatus.dwCheckPoint         = 0; 
    MyServiceStatus.dwWaitHint           = 0; 
 
    MyServiceStatusHandle = RegisterServiceCtrlHandler(NOME_DO_SERVICO, MyServiceCtrlHandler); 
 
    if ( MyServiceStatusHandle == (SERVICE_STATUS_HANDLE) 0 ) 
    { 
        MostrarErro(" [ServNT] RegisterServiceCtrlHandler failed %d\n", GetLastError()); 
        return; 
    } 
 
    if ( !SetServiceStatus (MyServiceStatusHandle, &MyServiceStatus) ) 
    { 
        status = GetLastError(); 
        MostrarErro(" [ServNT] SetServiceStatus error %ld\n", status); 
    } 

    // Initialization code goes here. 
	Event=CreateEvent(NULL,FALSE,FALSE,NULL); //semaforo binário

	if (Event==NULL) 
    { 
        MyServiceStatus.dwCurrentState       = SERVICE_STOPPED; 
        MyServiceStatus.dwCheckPoint         = 0; 
        MyServiceStatus.dwWaitHint           = 0; 
        MyServiceStatus.dwWin32ExitCode      = ERROR_SERVICE_SPECIFIC_ERROR; 
        MyServiceStatus.dwServiceSpecificExitCode = 0x1234; 
 
        SetServiceStatus (MyServiceStatusHandle, &MyServiceStatus); 
        return; 
    } 
 
    // Initialization complete - report running status. 
    MyServiceStatus.dwCurrentState       = SERVICE_RUNNING; 
    MyServiceStatus.dwCheckPoint         = 0; 
    MyServiceStatus.dwWaitHint           = 0; 
    MyServiceStatus.dwControlsAccepted   = SERVICE_ACCEPT_STOP/* | SERVICE_ACCEPT_PAUSE_CONTINUE*/; 
 
    if (!SetServiceStatus (MyServiceStatusHandle, &MyServiceStatus)) 
    { 
        status = GetLastError(); 
        ShowError(" [ServNT] SetServiceStatus error %ld\n",status); 
    } 
 
    // This is where the service does its work. 
    ShowError(" [ServNT] Waiting for clients \n",0); 
	flag=TRUE;

	while(flag) 
	{
		hPipe = CreateNamedPipe("\\\\.\\pipe\\ServNT",
			  PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED | FILE_FLAG_WRITE_THROUGH, PIPE_WAIT | 
			  PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE, PIPE_UNLIMITED_INSTANCES, 1024, 1024, 1000, NULL);

		if (!hPipe)
			break;

		ovl.hEvent=Event;
		ConnectNamedPipe(hPipe, &ovl);

		WaitForSingleObject(Event, INFINITE);

		if (!flag)
			break;

		CreateThread(NULL, 0, MyServiceProc, hPipe, 0, NULL);
	}
	CloseHandle(hPipe);
	CloseHandle(Event);

    MyServiceStatus.dwCurrentState       = SERVICE_STOPPED; 
    MyServiceStatus.dwCheckPoint         = 0; 
    MyServiceStatus.dwWaitHint           = 0; 
 
    if (!SetServiceStatus (MyServiceStatusHandle, &MyServiceStatus)) 
    { 
        status = GetLastError(); 
        ShowError("[ServNT] SetServiceStatus error %ld\n", status); 
    } 
 
    return; 
} 
 
VOID WINAPI MyServiceCtrlHandler (DWORD Opcode) 
{ 
    switch(Opcode) 
    { 
        case SERVICE_CONTROL_PAUSE: 
        // Do whatever it takes to pause here. 
//            MyServiceStatus.dwCurrentState = SERVICE_PAUSED; 
            break; 
 
        case SERVICE_CONTROL_CONTINUE: 
        // Do whatever it takes to continue here. 
//            MyServiceStatus.dwCurrentState = SERVICE_RUNNING; 
            break; 
 
        case SERVICE_CONTROL_STOP: 
        // Do whatever it takes to stop here. 
            MyServiceStatus.dwWin32ExitCode = 0; 
            MyServiceStatus.dwCurrentState  = SERVICE_STOP_PENDING; 
            MyServiceStatus.dwCheckPoint    = 0; 
            MyServiceStatus.dwWaitHint      = 0; 
 
            if (!SetServiceStatus (MyServiceStatusHandle, 
                &MyServiceStatus))
            { 
                status = GetLastError(); 
                MostrarErro(" [ServNT] SetServiceStatus error %ld\n",status); 
            } 
			flag=FALSE;
			SetEvent(Event);
            ShowError(" [ServNT] Leaving MyService \n",0); 
            return; 
 
        case SERVICE_CONTROL_INTERROGATE: 
        // Fall through to send current status. 
            break; 
 
        default: 
            ShowError(" [ServNT] Unrecognized opcode %ld\n", 
                Opcode); 
			break;
    } 
 
    // Send current status. 
    if (!SetServiceStatus (MyServiceStatusHandle,  &MyServiceStatus)) 
    { 
        status = GetLastError(); 
        ShowError(" [ServNT] SetServiceStatus error %ld\n",status); 
    } 
    return; 
} 
 

DWORD  WINAPI MyServiceProc(LPVOID param) //alterar para o nosso codigo/serviço
{
	char buffer[1024];
	HANDLE hPipe=(HANDLE) param;
    DWORD dwReadWrite;
    BOOL ret = FALSE;

	ShowError("Vou entrar na Thread\n",0);
	while(flag) 
	{
		buffer[0]=0;
		ret = ReadFile(hPipe, buffer, 1024, &dwReadWrite, NULL);

		if (!ret || !dwReadWrite) 
		{ 
	        status = GetLastError(); 
	        MostrarErro(" [ServNT] ReadFile error %ld\n", status); 
			break;
		}

		lstrcat(buffer, "...Ok!!!");

		ShowError(buffer,0);

		ret = WriteFile(hPipe, buffer, lstrlen(buffer)+1, &dwReadWrite, NULL);

		if (!ret || !dwReadWrite) 
		{ 
	        status = GetLastError(); 
	        ShowError(" [ServNT] WriteFile error %ld\n", status); 
			break;
		}

	}

	DisconnectNamedPipe(hPipe);
	CloseHandle(hPipe);
	ShowError(" [ServNT] Getting out of Thread\n",0);

	return 0L;
}

HANDLE hEventSource;

void ShowError(LPSTR str,DWORD val)
{
	char buf[1024];
	LPSTR msg[2]={buf,NULL};
	
	wsprintf(buf,str,val);

    if (!hEventSource) 
	{
        hEventSource = RegisterEventSource(NULL,            // local machine
                                           NOME_DO_SERVICO); // source name
    }

    if (hEventSource) 
	{
        ReportEvent(hEventSource,
                      EVENTLOG_INFORMATION_TYPE,
                      0,
                      0,
                      NULL,   // sid
                      1,
                      0,
                      (const char **)msg,
                      NULL);
    }

}

hi BobS0327, thanks for the reply

i changed the the ip of the target machine to it's computer name, and it didn't work either

Code:

char *pszPipe="\\\\TSCII03CLT1\\pipe\\ServNT";

What could be the problem?

My gut feeling is that it is some sort of security issue on the remote computer.

Hopefully, you'll humor me a little bit and add the following function to your code. Then call DisplayError immediately after you encounter the error. This will display a detailed message about the error. Thus, we won't have to use the "pulling at straws" method to determine the source of your problem. Post the detailed error message on the forum.

Code:

VOID DisplayError(CHAR* pMessage)
{
	DWORD eNum;
	CHAR sysMsg[256] = {0};
	CHAR* p;

	eNum = GetLastError( );
	FormatMessage( FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
		NULL, eNum,
		MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
		sysMsg, 256, NULL );
	// Trim the end of the line and terminate it with a null
	p = sysMsg;
	while( ( *p > 31 ) || ( *p == 9 ) )
		++p;
	do { *p-- = 0; } while( ( p >= sysMsg ) &&
		( ( *p == '.' ) || ( *p < 33 ) ) );
	// Display the message
	printf( "\n%s failed with error %d (%s)", pMessage, eNum, sysMsg );
}

EDIT I tested your code using a remote workstation and I didn't have any problems whatsoever. So, it really looks like a security issue on the remote workstation.

Perhaps the Windows Firewall is blocking this?

--
Mats

hi matsp.
It can't be the firewall, because i turned it off on both machines (local and virtual).

BobS0327: I'm going to try that and tell you what happened.

I tested your code using a remote workstation and I didn't have any problems whatsoever. So, it really looks like a security issue on the remote workstation.

If it is a security issue on the remote workstation, how can i resolve it?

Originally Posted by BobS0327

Finally, it would behoove you to discuss any changes you would like to make with your Network Administator. They normally have a very good reason for everything.

Or at least what THEY THINK is a good reason... And it may not be easy to change their decisions and reasoning here either.

--
Mats

BobS0327:
where do i add the function? On the server app or client app?
and were in the code do you want me to call it?

Originally Posted by IndioDoido

BobS0327:
where do i add the function? On the server app or client app?
and were in the code do you want me to call it?

You add it somewhere in the code where you are experiencing the failing call(s) to the OS - and add calls after all system calls that may fail.

--
Mats

In the client:

Code:

DWORD dwReadWritten;
	DWORD dwMode=PIPE_READMODE_MESSAGE|PIPE_WAIT;
	char buffer[1024];
    char *pszPipe="\\\\192.168.1.82\\pipe\\ServNT";

    if (!WaitNamedPipe(pszPipe, NMPWAIT_WAIT_FOREVER)) 
	{
                       DisplayError("waitNamedPipe error");
		printf("CLIENT: Error connecting\n");
		return 1;
	}

And as Matsp explained wherever else you're experiencing problems.

okay...
this is what i did:

Code:

char *pszPipe="\\\\192.168.1.80\\pipe\\ServNT";

if (!WaitNamedPipe(pszPipe, NMPWAIT_WAIT_FOREVER)) 
{
	DisplayError(pszPipe);
	return 1;
}

and this is the result error:

waitNamedPipe error faild with error 3 (System cannot find the path specified)

I did testes with the firewall on\off and the error was the same

What now? I'm against violence, but do i have to beat my virtual machine up?

sorry tabstop, i pasted the wrong thing
My previous post is now correct