PRB: recv() w/MSG_PEEK Always Returns Wrong Buffer Size

ID: Q140263

The information in this article applies to:

Microsoft Win32 Software Development Kit (SDK), versions 3.51, 4.0

SYMPTOMS

An Application that uses the Winsock 1.1 call recv(..., MSG_PEEK) repeatedly, will always receive the amount of data as in the first call. This amount only changes when you call recv without MSG_PEEK.

CAUSE

This is the result of a performance optimization within AFD.SYS.

RESOLUTION

recv() with MSG_PEEK should generally be avoided. It is a very inefficient way to retrieve data and definitely not recommended if you care about performance. A much better solution would be to simply receive the data into user buffers and use it directly from there.

STATUS

This behavior is by design.

Keywords : kbnetwork kbtshoot kbAPI kbNTOS351 kbNTOS400 kbSDKPlatform kbWinsock kbGrpNet
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Issue type : kbprb