Question

How to increase the TCP receive window for a specific socket?
– I know how to do so for all the sockets by setting the registry key TcpWindowSize,
but how do do that for a specific one?

According to MSFT’s documents, the way is

Calling the Windows Sockets function
setsockopt, which sets the receive
window on a per-socket basis.

But in setsockopt, it is mentioned about SO_RCVBUF :

Specifies the total per-socket buffer
space reserved for receives. This is
unrelated to SO_MAX_MSG_SIZE and does
not necessarily correspond to the size
of the TCP receive window.

So is it possible? How?

Thanks.

Answer 1

SO_MAX_MSG_SIZE is for UDP. Here’s from MSDN:

SO_MAX_MSG_SIZE – Returns the maximum outbound message size for message-oriented sockets supported by the protocol. Has no meaning for stream-oriented sockets.

It’s also not settable.

For TCP just use SO_(SND|RCV)BUF.