I am calling WTSQuerySessionInformationA in WTSAPI32. The result is returned as a pointer. I am probably not declaring it correctly or just confused as how to access the value or sometimes a structure depending on the requested WTSInfoClass. (I have only done simple API calls where the result buffer contains the actual values.)

#DEFINE WTS_CURRENT_SERVER 0
#DEFINE WTS_CURRENT_SESSION -1
#DEFINE WTSSessionId 4
#DEFINE WTSClientName 10
#DEFINE WTSClientAddress 14

DECLARE INTEGER WTSQuerySessionInformationA;
	IN WTSAPI32.DLL;
	INTEGER hServer,;
	INTEGER SessionId,;
	INTEGER WTSInfoClass,;
	STRING @ppBuffer,;
	INTEGER @pBytesReturned

lcBuffer = SPACE(4)
lnBufferSize = 0
lnRetval = WTSQuerySessionInformationA(WTS_CURRENT_SERVER_HANDLE,;
WTS_CURRENT_SESSION,;
WTSClientAddress,;
@lcBuffer,@lnBufferSize )

lcBuffer always contains 4 chars (pointer) and lnBufferSize will vary based on what is requested...

WTSSessionId returns 4.

WTSClientName returns 8.

WTSClientAddress returns 24 which is a structure (integer and 20 chars)

It all seems to work, and makes sense, but I am just brain dead on how to get it setup correctly to access the result.

Thanks for any guidance.

The struct buffer that comes back should contain a string (along with some funky characters) and you should be able to read the string data as an offset with SUBSTR() - offsetting for the pre-amble with the size for the string data. If the string is Unicode you may have to to strip off the double byte extra null characters.

+++ Rick ---

Thanks Rick. I am not being clear as to what I am seeing.

In the example, lcBuffer and lnBufferSize are passed by reference. The API returns a numeric value in lnBufferSize which indicates the size of the result. However, the result is stored in separate memory allocated by the API. The 4 byte value returned in lcBuffer points to that allocated memory. I can see and access these 4 bytes, but I am unclear as to how to take that value (address) and access the information stored at that address.

Ah Ok you need to de-reference the pointer returned...

You can use:

lcBuffer = SYS(2600,lnPointer,1024)

to get the data from the pointer. Then you can parse the data as described previously.

+++ Rick --

Well, that didn't seem to work either.

I suspect that the API is returning a 64 bit address and I probably just can't get there from here. I think I will shift gears and try calling powershell and extracting the info that way.

Thanks for your attempt. Your the best.

Stay well.

Your types aren't quite right. The pointer should be a number. I tried this but it still looks like the pointer that is returned is not to the right memory location for the data:

CLEAR
#DEFINE WTS_CURRENT_SERVER_HANDLE 0
#DEFINE WTS_CURRENT_SESSION -1
#DEFINE WTSSessionId 4
#DEFINE WTSClientName 10
#DEFINE WTSClientAddress 14

DECLARE INTEGER WTSQuerySessionInformationA;
	IN WTSAPI32.DLL;
	INTEGER hServer,;
	INTEGER SessionId,;
	INTEGER WTSInfoClass,;
	INTEGER @ppBuffer,;
	INTEGER @pBytesReturned

lnPointer = 0

lnBufferSize = 0
lnRetval = WTSQuerySessionInformationA(WTS_CURRENT_SERVER_HANDLE,;
WTS_CURRENT_SESSION,;
WTSClientAddress,;
@lnPointer,@lnBufferSize )
? lnBufferSize
? lnPointer

lcRes = SYS(2600,lnPointer,lnBufferSize)
? lcRes

+++ Rick ---