Network question...

[Pierre Bellisle]

Adam,
on my side, I see it that way...

Let say someone ask you for a buffer of 50 bytes,
in this buffer you have to put 3 names.
The buffer address in memory is 100.

(Let's replace CHR$(0) in buffer with "." so it's easier to read)

Buffer = "011201170125Adam.William.Bellisle................"
 
First  DWord is 0112 and it is the address of the first name
Second DWord is 0117 and it is the address of the second name
Third  DWord is 0125 and it is the address of the third name

Pierre



[This message has been edited by Pierre Bellisle (edited February 04, 2005).]

[Adam J. Drake]

I still don't understand it really (it's about to make me go cross-eyed), but I appreciate the info. Have updated my code to reflect these suggested changes.

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[Pierre Bellisle]

Adam,
I think William is right,
try the following code and see how szBuffer is filled,
4 first bytes is the address of UniversalName
and then, just following the address, we have our UniversalName...

This tell us that dwBufferSize should be %MAX_PATH + 4 + 1,
%MAX_PATH to be able to accept the maximum path lenght set by Windows,
+ 4 for the sise of the DWord address,
+ 1 for a terminating zero...

[Added]
To proove, set dwBufferSize to the
len of the UniversalName + 4 + 1,
the function will succeed but if you set
dwBufferSize smaller than that, the function will fail...

Pierre

#COMPILE EXE
#DIM ALL
#INCLUDE "WIN32API.INC"
 
FUNCTION PBMAIN() AS LONG
 LOCAL UniPointer    AS UNIVERSAL_NAME_INFO POINTER
 LOCAL szLocalPath   AS ASCIIZ * 3
 LOCAL szBuffer      AS ASCIIZ * %MAX_PATH + 5 'Add 5 becose DWord address and terminating zero
 LOCAL dwBufferSize  AS DWORD
 LOCAL dwInfoLevel   AS DWORD
 
 szLocalPath  = "P:" 'Put a valid network drive, ex: "P:"
 dwInfoLevel  = %UNIVERSAL_NAME_INFO_LEVEL
 dwBufferSize = SIZEOF(szBuffer)
 UniPointer   = VARPTR(szBuffer)
 
 IF WNetGetUniversalName(szLocalPath, dwInfoLevel, szBuffer, dwBufferSize) = %NO_ERROR THEN
   MSGBOX "Success : " & @[email protected] & $CRLF & _
          "Len =" & STR$(LEN(@[email protected]iversalName))
 ELSE
   MSGBOX "Error Occurred !"
 END IF
 
 LOCAL sBuffer AS STRING
 sBuffer = PEEK$(UniPointer, dwBufferSize)
 REPLACE $NUL WITH "." IN sBuffer
 MSGBOX sBuffer
 
END FUNCTION

[This message has been edited by Pierre Bellisle (edited February 03, 2005).]

[Michael Mattias]

> lpBufferSize as %MAX_PATH, because that's the size of the buffer pointed to by the structure.

  lpBufferSize  = SIZEOF(lpBuffer) -1   ' subtract one for the null terminator

This way if you change the size of lpbuffer, you don't have to also change your size thing.

[Adam J. Drake]

I don't understand why this would not be safe...

I didn't post the entire call, (and don't have it handy at home) but I am sending all that's required according to the documentation: WNetGetUniversalName MSDN Documentation

Specifying UNIVERSAL_NAME_INFO_LEVEL for dwInfoLevel

And at least as I'm reading it:

lpBuffer
[out] Pointer to a buffer that receives the structure specified by the dwInfoLevel parameter.

The UNIVERSAL_NAME_INFO structure only has one element, and ASCIIZ PTR, which I am creating, and specifying lpBufferSize as %MAX_PATH, because that's the size of the buffer pointed to by the structure.

Please don't get me wrong, I don't take offense at the comments, I'm just trying to understand what's now unsafe about the code...

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[William Burns]

I now set up the buffer like this and it seems to work:


LOCAL lpBuffer AS UNIVERSAL_NAME_INFO
LOCAL lpBufferSize AS DWORD
LOCAL tmppath AS ASCIIZ*%MAX_PATH
lpBufferSize = %MAX_PATH
lpBuffer.lpUniversalName=VARPTR(tmppath)
Is it safe?

Without seeing the way you are calling the WNetGetUniversalName() function, I can't say for
sure, but... that does not look safe either. Assuming you are calling the function using the
lpBuffer for the parameter. Because this is still trying to place the data in the lpBuffer
variable which is still only a single DWORD that holds a pointer. To make that work you will
need to pass the pointer to the tmppath variable so it will store the data there.

------------------
"I haven't lost my mind... its backed up on tape... I think??"



[This message has been edited by William Burns (edited February 03, 2005).]

[Adam J. Drake]

William, Thanks for the reply.

I now set up the buffer like this and it seems to work:

    LOCAL lpBuffer      AS UNIVERSAL_NAME_INFO
    LOCAL lpBufferSize  AS DWORD              
    LOCAL tmppath       AS ASCIIZ*%MAX_PATH

    lpBufferSize = %MAX_PATH
    lpBuffer.lpUniversalName=VARPTR(tmppath)

Is it safe?

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[William Burns]

I guess I'm not understanding the whole pointer thing.

Most of the time things like that require me to create a buffer variable to receive the data, and set it to VARPTR(szBuf).

Why is this one different?

Adam this is not different. You need to provide a buffer before you call the function. The above example works because
it is writing over the neighbors memory space, which is sometimes empty. (this is dangerous, and will eventually bite you)
There are a few windows functions that will create their own buffer space and return a pointer to it. If they do, they
will generally rely on you releasing the memory after you are done. But the Win32API documents will tell you that.
But in this case, you are on your own to create a buffer ahead of time.

You should do something similar to this:

'=========================================================
#Compile Exe
#Dim All
#Include "WIN32API.INC"

'=========================================================
Function GetUNC(ByVal sDriveLetter As String) As String
   Local iRet           As Long
   Local zLocalDrive    As Asciiz * 10
   Local UNI            As UNIVERSAL_NAME_INFO Ptr
   Local zBuff          As Asciiz * %MAX_PATH
   Local dBufSize       As Dword
   If Len(sDriveLetter) <> 2 Or Mid$(sDriveLetter,2,1) <> ":" Then Exit Function
   zLocalDrive = sDriveLetter
   UNI = VarPtr(zBuff)
   dBufSize = %MAX_PATH
   If WNetGetUniversalName(zLocalDrive, ByVal %UNIVERSAL_NAME_INFO_LEVEL, zBuff, dBufSize) = %NO_ERROR Then
      Function = @[email protected]
   Else
      iRet = GetLastError()
      If iRet = 2250 Then 'Drive mapping does not exist so report nothing back for answer
      Else  'unknown error so report it 
         Function = "Error" + Str$(iRet)
      End If
   End If
End Function
'=========================================================

Function PbMain()
   Local sLetter As String
   sLetter = InputBox$("Type the Drive letter to get the UNC name for:  (Ex: J    [img]http://www.powerbasic.com/support/forums/smile.gif[/img]",,"F:")
   MsgBox GetUNC(sLetter),,sLetter
End Function
'=========================================================

------------------
"I haven't lost my mind... its backed up on tape... I think??"



[This message has been edited by William Burns (edited February 02, 2005).]

[Adam J. Drake]

Ok, cool.

I guess I'm not understanding the whole pointer thing.

Most of the time things like that require me to create a buffer variable to receive the data, and set it to VARPTR(szBuf).

Why is this one different?

------------------

[Pierre Bellisle]

Adam,
about %REMOTE_NAME_INFO_LEVEL,
I forgot to remove it when I posted the code,
it is now remed,
it worked becose in both type, the first element is the same name and type...
see...

TYPE REMOTE_NAME_INFO
  lpUniversalName  AS ASCIIZ PTR '<<<
  lpConnectionName AS ASCIIZ PTR
  lpRemainingPath  AS ASCIIZ PTR
END TYPE

TYPE UNIVERSAL_NAME_INFO
  lpUniversalName AS ASCIIZ PTR '<<<
END TYPE

Pierre

[Adam J. Drake]

Pierre,

Documentation says %REMOTE_NAME_INFO_LEVEL returns a REMOTE_NAME_INFO structure, though I am using a UNIVERSAL_NAME_INFO structure, which only has 1 ASCIIZ PTR var instead of 3 in REMOTE_NAME_INFO. I am curious, why does this work?

------------------

[Adam J. Drake]

Works beautifully, thank you for the help.


------------------

[Pierre Bellisle]

Adam,
try the following...

Pierre

#COMPILE EXE
#DIM ALL
#INCLUDE "WIN32API.INC"
FUNCTION PBMAIN() AS LONG
 LOCAL lpLocalPath   AS ASCIIZ * %MAX_PATH
 LOCAL lpBuffer      AS UNIVERSAL_NAME_INFO
 LOCAL dwInfoLevel   AS DWORD
 LOCAL lpBufferSize  AS DWORD
 
 dwInfoLevel  = %UNIVERSAL_NAME_INFO_LEVEL
 'dwInfoLevel = %REMOTE_NAME_INFO_LEVEL
 lpBufferSize = %MAX_PATH
 lpLocalPath  = "F:"
 
 IF WNetGetUniversalName(lpLocalPath, dwInfoLevel, lpBuffer, lpBufferSize) = %NO_ERROR THEN
   MSGBOX "Success : " & [email protected]
 ELSE
   MSGBOX "Error Occurred."
 END IF
 
END FUNCTION

[This message has been edited by Pierre Bellisle (edited January 19, 2005).]

[Adam J. Drake]

I'm only wanting to get one particular UNC path, but no matter what drive letter I try here, it returns success, with no info.

What am I doing wrong?

#INCLUDE "WIN32API.INC"

FUNCTION PBMAIN() AS LONG

    LOCAL lpLocalPath   AS ASCIIZ*%MAX_PATH
    LOCAL dwInfoLevel   AS DWORD
    LOCAL lpBuffer      AS UNIVERSAL_NAME_INFO
    LOCAL lpBufferSize  AS DWORD
    LOCAL szBuf         AS ASCIIZ*%MAX_PATH
    
    dwInfoLevel=%UNIVERSAL_NAME_INFO_LEVEL
    lpBufferSize=%MAX_PATH
    lpBuffer.lpUniversalName=VARPTR(szBuf)
    
    lpLocalPath="F:"
    
    IF WNetGetUniversalName(lpLocalPath,dwInfoLevel,lpBuffer,lpBufferSize)<>0 THEN
        MSGBOX "Error Occurred."
    ELSE
        MSGBOX "Success. "+szBuf
    END IF

END FUNCTION

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[Adam J. Drake]

Pierre, thanks for the info, exactly what I needed.

------------------

[Pierre Bellisle]

adam,
some stuff by william burns should get you started...
http://www.powerbasic.com/support/pb...ad.php?t=20906

[Adam J. Drake]

Well, I have an in-house utility that the shortcut runs an auto-updater for that utility every time it's ran, then based on whether or not they have that drive letter available, I launch either a version that accesses that drive directly, or accesses it via in-house web servers with CGI stuff.

The problem is some people map the "real" drive as something else sometimes.

What I'd like to do is check the mapping of that drive (if it's there), then launch the correct version of the utility.

I currently have no code as I don't have a clue how to do this.

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[This message has been edited by Adam J. Drake (edited January 15, 2005).]

[Donald Darden]

Can you give me an example of how you want to use this? Have you
tried it?

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Old Navy Chief, Systems Engineer, Systems Analyst, now semi-retired

[Adam J. Drake]

Is it possible to get a string representation of a network drive mapping in a program?

(ie: F: "\\SERVER1\VOL_INFO")

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