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To: Terry Lambert <tlambert2@mindspring.com>
Cc: net@freebsd.org
Subject: Re: soisdisconnected tweak. 
In-reply-to: Your message of "Sun, 28 Apr 2002 18:07:51 PDT."
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Date: Mon, 29 Apr 2002 10:06:56 +0100
From: David Malone <dwmalone@maths.tcd.ie>
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> A shutdown guarantees that the data is transferred from the socket
> buf to the TCP buf.  The real question here is how you get to the
> state you claim is happening: the so isdisconnected() should stall
> the calling process until the data has drained, if this is the case,
> or it should never get called until the buffer is empty.

I think your fears about data being lost here may be unfounded.
The description of soisdisconnected() says:

	... soisdisconnected() is called when the connection to the
	peer is totally severed.

This seems to mean that that either the connection has timed out
or has been aborted. I think it should be safe to drop any data
which is waiting to be sent if connection is actually severed.

I've included a list of the places where soisdisconnected is called
from, and they all seem pretty final.

	David.

unp_detach
unp_disconnect
raw_uabort
raw_udisconnect
ddp_disconnect
ddp_abort
at_pcbdetach
atm_sock_connect (if connect fails)
ngs_rmnode
div_abort
rip_abort
tcp_input (TCPS_FIN_WAIT_1 && ourfinisacked) || (TCPS_CLOSING && ourfinisacked)
          || (TCPS_FIN_WAIT_2 && FIN)
tcp_close
tcp_usrclosed (and we're in state >= TCPS_FIN_WAIT_2)
udp_abort
rip6_abort
udp6_abort
ipx_abort
ipx_drop
ipx_usr_abort
ipx_disconnect
spx_close
natm_usr_disconnect
natm_usrreq for PRU_DISCONNECT
idp_abort
idp_drop
idp_usrreq for PRU_DISCONNECT and PRU_ABORT
spp_close

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