PSS ID Number: 168187
Article Last Modified on 10/27/2003
The information in this article applies to:
- Microsoft Win32 Application Programming Interface (API), when used with:
- the operating system: Microsoft Windows 95
This article was previously published under Q168187
SYMPTOMS
Data buffers passed to the Windows Sockets recv() function have the
potential to lose the data they contain. This problem only affects buffers
passed to recv(). Data buffers manipulated solely by the application or by
APIs other than recv() are not affected by this problem.
More specifically, this problem only affects the first WinSock 2 Update for Windows 95. For additional information about this update, please see the following article in the Microsoft Knowledge Base:
182108 Availability of Windows Sockets 2.0 for Windows 95
For additional information about the second version of the WinSock 2 Update for Windows 95, please see the following article in the Microsoft Knowledge Base:
184242 WinSock 2.0 Installer for Windows 95 (Ws2setup.exe) Update
This problem does not apply to any other Windows platform.
CAUSE
The recv() function accepts a buffer to be filled with data received over a
socket connection. For memory management purposes, the system may discard
portions of such a buffer to allow other memory activity of the system to
proceed successfully. When the system does this, it first checks the memory
page's "dirty" bit to determine if the page should be written to the paging
file before being discarded. When the memory is later needed, it is
retrieved from the paging file intact.
The memory pages touched by recv() are supposed to be marked "dirty" when
modified so that the pages will be properly written to the system paging
file before the memory is discarded. In Windows 95, the pages are not
marked "dirty." This causes the pages to be discarded without first being
written to the paging file. When the data is later needed by the
application, it is treated similar to newly-allocated zero-initialized memory.
Such data received over the socket connection earlier is now lost.
RESOLUTION
Install the latest update to WinSock 2 for Windows 95 as described in the following article in the Microsoft Knowledge Base:
184242 WinSock 2.0 Installer for Windows 95 (Ws2setup.exe) Update
STATUS
Microsoft has confirmed this to be a bug in the Microsoft products listed
at the beginning of this article.
Keywords: kbAPI kbBug kbnetwork kbWinsock KB168187
Technology: kbAudDeveloper kbOSWin95 kbOSWinSearch kbWin32API kbWin32sSearch