2002-03-18 09:55:03 +00:00
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.\" $OpenBSD: nchan2.ms,v 1.2 2001/10/03 10:05:57 markus Exp $
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.\"
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.\" Copyright (c) 2000 Markus Friedl. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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2000-05-15 04:37:24 +00:00
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.TL
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OpenSSH Channel Close Protocol 2.0 Implementation
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.SH
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Channel Input State Diagram
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.PS
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reset
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l=1
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s=1.2
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ellipsewid=s*ellipsewid
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boxwid=s*boxwid
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ellipseht=s*ellipseht
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S1: ellipse "INPUT" "OPEN"
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move right 2*l from last ellipse.e
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S3: ellipse invis
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move down l from last ellipse.s
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S4: ellipse "INPUT" "CLOSED"
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move down l from 1st ellipse.s
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S2: ellipse "INPUT" "WAIT" "DRAIN"
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arrow from S1.e to S4.n
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box invis "rcvd CLOSE/" "shutdown_read" with .sw at last arrow.c
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arrow "ibuf_empty ||" "rcvd CLOSE/" "send EOF" "" from S2.e to S4.w
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arrow from S1.s to S2.n
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box invis "read_failed/" "shutdown_read" with .e at last arrow.c
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ellipse wid .9*ellipsewid ht .9*ellipseht at S4
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arrow "start" "" from S1.w+(-0.5,0) to S1.w
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.PE
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.SH
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Channel Output State Diagram
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.PS
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S1: ellipse "OUTPUT" "OPEN"
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move right 2*l from last ellipse.e
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S3: ellipse invis
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move down l from last ellipse.s
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S4: ellipse "OUTPUT" "CLOSED"
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move down l from 1st ellipse.s
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S2: ellipse "OUTPUT" "WAIT" "DRAIN"
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arrow from S1.e to S4.n
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box invis "write_failed/" "shutdown_write" with .sw at last arrow.c
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arrow "obuf_empty ||" "write_failed/" "shutdown_write" "" from S2.e to S4.w
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arrow from S1.s to S2.n
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box invis "rcvd EOF ||" "rcvd CLOSE/" "-" with .e at last arrow.c
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ellipse wid .9*ellipsewid ht .9*ellipseht at S4
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arrow "start" "" from S1.w+(-0.5,0) to S1.w
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.PE
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.SH
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Notes
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.PP
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The input buffer is filled with data from the socket
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(the socket represents the local consumer/producer of the
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forwarded channel).
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The data is then sent over the INPUT-end (transmit-end) of the channel to the
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remote peer.
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Data sent by the peer is received on the OUTPUT-end (receive-end),
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saved in the output buffer and written to the socket.
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.PP
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If the local protocol instance has forwarded all data on the
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INPUT-end of the channel, it sends an EOF message to the peer.
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.PP
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A CLOSE message is sent to the peer if
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both the INPUT- and the OUTOUT-half of the local
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end of the channel are closed.
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.PP
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The channel can be deallocated by a protocol instance
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if a CLOSE message he been both sent and received.
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