Q247826: BUG: Using a QoS Socket with AcceptEx

Article: Q247826
Product(s): Microsoft Windows NT
Version(s): WINDOWS:
Operating System(s): 
Keyword(s): kbnetwork kbAPI kbGQos kbOSWin2000 kbSDKPlatform kbSDKWin32 kbDSupport kbGrpDSNet
Last Modified: 24-OCT-2000

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The information in this article applies to:

- Microsoft Windows 2000 Advanced Server 
- Microsoft Windows 2000 Server 
- Microsoft Windows 2000 Professional 
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SYMPTOMS
========

The AcceptEx function exhibits several problems when used with a Quality of
Service (QoS) socket:

- The AcceptEx function drops incoming data if it is used with a QoS socket and
  if AcceptEx is called with its dwReceiveDataLength parameter set to a value
  great than 0 (zero). If AcceptEx is called with dwReceiveDataLength set to a
  value of N (N greater than 0), then the application calling AcceptEx never
  receives the N bytes of data. Furthermore, the lost data cannot be
  subsequently retrieved by calling recv or WSARecv after calling AcceptEx.

- The AcceptEx function may access violate if the lpOutputBuffer parameter
  passed in is NULL.

- The lpOverlapped parameter to AcceptEx must not be NULL.

- The sAcceptSocket parameter used in AcceptEx will not inherit the properties
  of the sListenSocket parameter after setsockopt(SO_UPDATE_ACCEPT_CONTEXT) is
  called, as documented for this function.

RESOLUTION
==========

To use the AcceptEx function with a QoS socket, please use the following
guidelines:

- Set the dwReceiveDataLength parameter in AcceptEx to 0, which tells AcceptEx
  to return as soon as a connection has been established. To obtain the data
  sent, call either recv or WSARecv.

- Do not pass in NULL for the lpOutputBuffer parameter when calling AcceptEx
  (even though you do not intend to receive initial data as described in the
  previous item). Instead, provide a buffer size greater than or equal to (2 *
  (sizeof(sockaddr_in) + 16) = 64.

- Call AcceptEx in an overlapped fashion and pass a pointer to a properly
  initialized overlapped structure in the lpOverlapped parameter in AcceptEx.

- Set the dwLocalAddressLength and dwRemoteAddressLength parameters to
  (sizeof(sockaddr_in) + 16) = 32 when calling AcceptEx (and
  GetAcceptExSockaddrEx--see next item).

- Call the GetAcceptExSockaddrEx function prior to calling
  setsockopt(SO_UPDATE_ACCEPT_CONTEXT) in order to have the sAcceptSocket
  parameter inherit the QoS properties of the sListenSocket parameter. If you
  do not call the GetAcceptExSockaddrEx function, then you will have to
  explicitly get the QoS settings for sListenSocket by using
  WSAIoctl(SIO_GET_QOS), and then set QoS on sAcceptSocket by using
  WSAIoctl(SIO_SET_QOS).

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

REFERENCES
==========

For additional information about creating a QoS socket, click the article number
below to view the article in the Microsoft Knowledge Base:

  Q192120 HOWTO: Use the WSAPROTOCOL_INFO Structure to Create a Socket

Additional query words:

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Keywords          : kbnetwork kbAPI kbGQos kbOSWin2000 kbSDKPlatform kbSDKWin32 kbDSupport kbGrpDSNet 
Technology        : kbwin2000AdvServ kbwin2000AdvServSearch kbwin2000Serv kbwin2000ServSearch kbwin2000Search kbwin2000ProSearch kbwin2000Pro kbWinAdvServSearch
Version           : WINDOWS:
Issue type        : kbbug

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