Microsoft KB Archive/295079

= Server Refuses Connection That Uses Winsock Listen Call Backlog Parameter =

Article ID: 295079

Article Last Modified on 1/31/2007

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APPLIES TO


 * Microsoft Windows 2000 Service Pack 1
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Service Pack 1

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This article was previously published under Q295079



SYMPTOMS
When you use the Winsock listen call backlog parameter, the server may refuse the connection. This can prevent passing of Windows Hardware Quality Labs (WHQL) tests, making it difficult for you to get certified for Winsock Direct.



CAUSE
This behavior can occur if the available listen backlog has become 0 instead of 1. When server side calls an accept parameter, this increments the available backlog by 1. However, this increment does not take place until the program thread is preempted. The server refuses a connection attempt during this time.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows 2000 Service Pack 2.



RESOLUTION
To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 How to Obtain the Latest Windows 2000 Service Pack



MORE INFORMATION
When a connection-oriented Winsock program is accepting incoming connections, a socket is created by calling socket and bind, a backlog for incoming connections is specified with listen, and then the connections are accepted with accept.

The listen function has a backlog parameter that specifies the maximum length of the pending-connection queue, where connection requests reside while they wait for the server program to execute the accept call. The maximum value of the backlog parameter varies, depending on what version of Windows NT you are running. If a connection request is received and the pending-connection queue is full, Windows NT issues TCP/IP resets on subsequent connection requests.

Keywords: kbbug kbfix KB295079

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