SPX Data Stream Type Header May Reset Unexpectedly

 Last reviewed: November 18, 1997
Article ID: Q153665
The information in this article applies to:
  • Microsoft Windows NT Workstation versions 3.51 and 4.0
  • Microsoft Windows NT Server version 3.51 and 4.0

SYMPTOMS

The SPX Data Stream Type (DS_TYPE) portion of the SPX packet header may reset unexpectedly in socket applications that use the DS_TYPE socket option.

CAUSE

When the DS_TYPE option is set, SPX sets a global flag that is specific to that connection indicating what the new DS_TYPE value should be on Sends. Because the global flag can be reset before Sends queued in SPX are transmitted on the network, the potential exists for the DS_TYPE to be changed before pending Sends have been transmitted.

In the following example, the application is intended to complete five Sends with DS_TYPE set to 1:

Example:

  1. Application sets the SPX DS_TYPE to 1

  2. Application indicates five Sends that are queued in SPX.

  3. SPX completes four of the Sends on the network using DS_TYPE 1.

  4. Application sets the SPX DS_TYPE to 0.

  5. SPX completes the remaining Send on the network using DS_TYPE 0.

The example above fails because the DS_TYPE has been changed before the final queued Send has completed.

RESOLUTION

Obtain the fix mentioned below. SPX has been modified to submit the DS_TYPE with every request instead of setting DS_TYPE before the actual Send.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.51 and 4.0. This problem was corrected in the latest Windows NT 3.51 U.S. Service Pack and in the latest Windows NT 4.0 U.S. Service Pack. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces): 

   S E R V P A C K

Additional query words: prodnt 3.51 4.00
Keywords : kbbug3.51 kbbug4.00 kbfix4.00.sp2 NTINTEROP kbnetwork
Version : 3.51 4.0
Platform : winnt
Issue type : kbbug
Solution Type : kbservicepack

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Last reviewed: November 18, 1997
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