INFO: WSA_FLAG_OVERLAPPED Needed for Timeout on WSASocket

ID: Q181610

The information in this article applies to:

• Microsoft Win32 Software Development Kit (SDK) on the following platforms:

  - Windows NT, version 4.0

  - Windows 95

SUMMARY

If you create a socket using the Winsock 2 WSASocket API and you need to apply a timeout in receive or send operations on the socket, you must specify the WSA_FLAG_OVERLAPPED flag in the WSASocket call.

MORE INFORMATION

If a socket is created without the overlapped I/O attribute, all I/O operations on the socket are synchronous. So if your program has set socket options SO_SNDTIMEO and SO_RCVTIMEO, you need to make sure your socket is created with the overlapped I/O attribute to timeout your blocking send or receive operations.

The overlapped I/O attribute of a socket created via the socket API is set internally. If you use WSASocket API, you need to set the WSA_FLAG_OVERLAPPED flag yourself in the last parameter of this API call.

Additional query words:

Keywords          : kbnetwork kbAPI kbNTOS400 kbSDKPlatform kbWinOS95 kbWinsock kbGrpNet 
Issue type        : kbinfo

Last Reviewed: July 31, 1998