I need help with connecting to remote named pipes...

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I have a service running in Session 0 on one computer, say A, that creates a named pipe and waits for a connection. On another computer, say B, I have another service that acts a pipe client and tries to connect to the named pipe on computer A, but gets GLE=5.

I have tried with the same two services running on same computer, and the named pipe communication has been absolutely smooth.

Can someone point out if I have missed anything when creating named pipe?
Do I need to do any settings on both the servers for this to work ?

I have been working on this since long time and need to get this working..

Thanks.

What I have tried:

I have used VC6.0 for the named pipe code.

When creating name pipe, I have tried with with:
1. Security Attributes=NULL,
2. Initialized SA with default values, and
3. The pipe mode was ORed with PIPE_ACCEPT_REMOTE_CLIENTS.

All of these methods have not given success.

Posted 11-Nov-19 4:32am

Gurudatt 8032986

Updated 11-Nov-19 5:01am

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Richard MacCutchan 11-Nov-19 10:58am

Please update the question and show the code for both processes that open the pipe and check the return value.

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Rick York · Answer 1 · 2019-11-11T05:02:00

Are you attaching to the pipe with a name of the form : "\\ComputerName\pipe\PipeName", where ComputerName is the name of the machine the pipe server is running on and PipeName is the name of the pipe?

The open call should be something like :

hpipe = CreateFile( pipeName, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL );

Here's one rather tricky aspect of the code I was using :

////////////////////////////////////////////////////////////////

static BOOL EstablishNullSession( const char* computerName )
{
    NETRESOURCE nr = { 0 };
    char server[MAX_PATH+1] = { 0 };
    DWORD ret;

    if( streq( computerName, "." ) )
    {
        strcpy( server, computerName );
    }
    else
    {
        strcpy( server, "\\\\" );
        strcat( server, computerName );
    }

    nr.dwType       = RESOURCETYPE_ANY;
    nr.lpRemoteName = server;

    ret = WNetAddConnection2( &nr, "", "", 0 );
    if( ret != ERROR_SUCCESS )
    {
        DisplayError( "WNetAddConnection2" );
        return FALSE;
    }
    return TRUE;
}

/////////////////////////////////////////////////////////////////////

TPipe ConnectToPipe( const char * pipename, const char * nodename,
                     int retries, int waitsecs ) )
{
    printf( "connecting to pipe '%s'\n", name );
    TPipe hpipe = { 0 };
    bool triedLogin = false;
    DWORD tries = 0;
    DWORD lastError = 0;
    DWORD openType = GENERIC_READ | GENERIC_WRITE;

    while( TRUE )
    {
        hpipe = CreateFile( name, openType, 0, NULL, OPEN_EXISTING, 0, NULL );

        // check that the pipe's handle is valid

        if( hpipe != INVALID_HANDLE_VALUE )
            break;                           // succeeded

        lastError = GetLastError();

        // if server not present yet try again

        if( lastError == ERROR_FILE_NOT_FOUND )
        {
            if( tries > retries )
            {
                DisplayError( "CreateFile" );
                return 0;
            }
            ++tries;
            Sleep( 500 );
            continue;
        }
        else if( ( lastError == ERROR_LOGON_FAILURE ) ||
                 ( lastError == ERROR_ACCESS_DENIED ) ||
                 ( lastError == ERROR_INVALID_PASSWORD ) )
        {
            if( triedLogon )
            {
                return 0;
            }
            else  // this is the tricky part
            {
                if( EstablishNullSession( nodename ) )
                {
                    printf( "established Null session.\n" );
                }
                else
                {
                    return 0;
                }
                triedLogon = true;
                continue;
            }
        }
        else if( lastError == ERROR_PIPE_BUSY )
        {
            printf( "the pipe was busy - waiting" );
            if( ! WaitNamedPipe( name, 1000 * waitsecs ) )
            {
                DisplayError( "WaitNamedPipe" );
                return 0;
            }
        }
        else // something else happened
        {
            DisplayError( "CreateFile" );
            return 0;
        }
    }

    mode = PIPE_READMODE_MESSAGE;
    if( ! SetNamedPipeHandleState( hpipe, &mode, NULL, NULL ) )
    {
        DisplayError( "SetNamedPipeHandleState " );
        return 0;
    }
    return (TPipe)hpipe;
}

I believe TPipe was defined as a ULONG. This is rather old code that I haven't tried in a while but it worked quite well at the time.

Best of luck with it.