From owner-freebsd-net  Thu Mar  8 21:56:38 2001
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To: Jonathan Lemon <jlemon@flugsvamp.com>
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Subject: Re: [itojun@iijlab.net: accept(2) behavior with tcp RST right after handshake]
From: itojun@iijlab.net
Date: Fri, 09 Mar 2001 14:56:21 +0900
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>From the server's point of view:
>
>    + TCP/IP handshake from client, allocate protocol control blocks
>    + receive data from client
>    + client resets connection, pcb is destroyed 
>
>Exactly why the client resets the connection isn't my concern at 
>the moment.  Some stacks may place a timeout on the FIN_WAIT state,
>and forcibly reset the reset the connection when the timer expires.
>Alternatively, the client may crash, and then RST in response to
>an ACK transmitted by the server.  Or the other end may have set 
>SO_LINGER, which will cause close() to send a RST.
>
>The unix-domain bug is because we were treating sockets in the
>DISCONNECTED state identically across all protocols, which turns
>out not to be the case.
>
>As for any data that already exists in the socket buffer on the
>server when the connection is aborted, I believe that the correct
>thing to do is discard it.  This is the historical precedent, and
>is supported by the current standards.
>
>Below is a patch that will fix the behavior for unix-domain sockets.

	from code inspection on netbsd, I guess you'd need to do something for
	other sys/net* families.  maybe we need another per-domain/per-socket
	flag for this?

itojun

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