Has anyone gotten WTSQuerySessionInformation API call from terminal services to work?

Stephen Seltzer

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May 8, 2003, 5:14:26 PM5/8/03

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I am trying to get the client host name from a terminal services session.
The call is succeeding and it is returning back the correct number of bytes
in the pBytesReturned parameter (hostname length + 1 char) but the
information in the ppBuffer is not rendering correctly on the screen (it is
just garbage). Here is what I am doing:

Local External Functions:
Function Boolean WTSQuerySessionInformationA( uLong hServer, uLong
SessionId, uLong WTSInfoClass, Ref String ppBuffer, Ref uLong
pBytesReturned) Library "Wtsapi32.dll"

Script:
Boolean Success
Integer RetVal = 0
uLong ll_BuffLen = 256

//First we must initialize the string to 256 characters for API
compatability.
is_HostName = Space(256)

Success = WTSQuerySessionInformationA(WTS_CURRENT_SERVER_HANDLE,
WTS_CURRENT_SESSION, WTSClientName, is_HostName,ll_BuffLen)
MessageBox('Debug','HostName: ' + is_HostName + '~nSuccess: ' +
String(Success) + '~nBuffer Size: ' + String(ll_BuffLen))

Instance Variable Declarations:
String is_HostName
Private Constant uLong WTS_CURRENT_SERVER_HANDLE = 0
Private Constant uLong WTS_CURRENT_SESSION = -1

Private Constant uLong WTSInitialProgram = 0
Private Constant uLong WTSApplicationName = 1
Private Constant uLong WTSWorkingDirectory = 2
Private Constant uLong WTSOEMId = 3
Private Constant uLong WTSSessionId = 4
Private Constant uLong WTSUserName = 5
Private Constant uLong WTSWinStationName = 6
Private Constant uLong WTSDomainName = 7
Private Constant uLong WTSConnectState = 8
Private Constant uLong WTSClientBuildNumber = 9
Private Constant uLong WTSClientName = 10
Private Constant uLong WTSClientDirectory = 11
Private Constant uLong WTSClientProductId = 12
Private Constant uLong WTSClientHardwareId = 13
Private Constant uLong WTSClientAddress = 14
Private Constant uLong WTSClientDisplay = 15
Private Constant uLong WTSClientProtocolType = 16

TIA,
Steve

Stephen Seltzer

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Jul 16, 2003, 2:26:32 PM7/16/03

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I figured out what was happening and figured I would share with the group.
WTSQuerySessionInformationA returns a pointer to a string and not an actual
string. By changing the ppBuffer variable to a uLong I was able to get the
pointer. I then mapped:
SUBROUTINE WTSFreeMemory( ULONG pMemory ) Library "Wtsapi32.dll"
SUBROUTINE MoveMemoryPointerToString( REF String Destination, ULong
ul_Source, ULong ul_Size ) Library "KERNEL32.DLL" Alias For "RtlMoveMemory"

Where ul_Source gets the value from ppBuffer and ul_Size gets the value from
pBytesReturned.

I hope this helps someone!

Steve

"Stephen Seltzer" <ssel...@dsicdi.com> wrote in message
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woz

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Jul 16, 2003, 2:59:51 PM7/16/03

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There is a little known thing in PB:

string(ll_pointer, "address")

It's used to make a string out of a powerobject pointer in message.longparm.

I wonder if this would have worked for you, too?

Generally, I feel the less external calls you make, the better. Wonder if this
could have worked for such a case?

Anatole Tartakovsky

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Jul 16, 2003, 2:32:27 PM7/16/03

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Another little known thing about string(ll_pointer, "address") is that PB
acquires lock on the memory that is never released - causing memory leak -
good for casual API use, but very dangerous for repeatabale communications.
Can be hard to notice with large memory/short testing, but definetly there
and problem with users using less memory and larger data sets
Regards,
Anatole
www.xmlsp.com

"woz" <ab...@msn.com> wrote in message news:3F15A0A7...@msn.com...