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Annotation of src/usr.bin/ssh/nchan.ms, Revision 1.6.2.2

1.6.2.1   jason       1: .\"    $OpenBSD: nchan.ms,v 1.7 2001/01/29 01:58:17 niklas Exp $
                      2: .\"
1.4       markus      3: .\"
                      4: .\" Copyright (c) 1999 Markus Friedl.  All rights reserved.
                      5: .\"
                      6: .\" Redistribution and use in source and binary forms, with or without
                      7: .\" modification, are permitted provided that the following conditions
                      8: .\" are met:
                      9: .\" 1. Redistributions of source code must retain the above copyright
                     10: .\"    notice, this list of conditions and the following disclaimer.
                     11: .\" 2. Redistributions in binary form must reproduce the above copyright
                     12: .\"    notice, this list of conditions and the following disclaimer in the
                     13: .\"    documentation and/or other materials provided with the distribution.
                     14: .\"
                     15: .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
                     16: .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
                     17: .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
                     18: .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
                     19: .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
                     20: .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
                     21: .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
                     22: .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
                     23: .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
                     24: .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
                     25: .\"
1.1       markus     26: .TL
                     27: OpenSSH Channel Close Protocol 1.5 Implementation
                     28: .SH
                     29: Channel Input State Diagram
                     30: .PS
                     31: reset
                     32: l=1
                     33: s=1.2
                     34: ellipsewid=s*ellipsewid
                     35: boxwid=s*boxwid
                     36: ellipseht=s*ellipseht
                     37: S1: ellipse "INPUT" "OPEN"
                     38: move right 2*l from last ellipse.e
                     39: S4: ellipse "INPUT" "CLOSED"
                     40: move down l from last ellipse.s
                     41: S3: ellipse "INPUT" "WAIT" "OCLOSED"
                     42: move down l from 1st ellipse.s
                     43: S2: ellipse "INPUT" "WAIT" "DRAIN"
                     44: arrow "" "rcvd OCLOSE/" "shutdown_read" "send IEOF" from S1.e to S4.w
                     45: arrow "ibuf_empty/" "send IEOF" from S2.e to S3.w
                     46: arrow from S1.s to S2.n
                     47: box invis "read_failed/" "shutdown_read" with .e at last arrow.c
                     48: arrow  from S3.n to S4.s
                     49: box invis "rcvd OCLOSE/" "-" with .w at last arrow.c
                     50: ellipse wid .9*ellipsewid ht .9*ellipseht at S4
                     51: arrow "start" "" from S1.w+(-0.5,0) to S1.w
1.5       markus     52: arrow from S2.ne to S4.sw
                     53: box invis "rcvd OCLOSE/     " with .e at last arrow.c
                     54: box invis " send IEOF" with .w at last arrow.c
1.1       markus     55: .PE
                     56: .SH
                     57: Channel Output State Diagram
                     58: .PS
                     59: S1: ellipse "OUTPUT" "OPEN"
                     60: move right 2*l from last ellipse.e
                     61: S3: ellipse "OUTPUT" "WAIT" "IEOF"
                     62: move down l from last ellipse.s
                     63: S4: ellipse "OUTPUT" "CLOSED"
                     64: move down l from 1st ellipse.s
                     65: S2: ellipse "OUTPUT" "WAIT" "DRAIN"
                     66: arrow "" "write_failed/" "shutdown_write" "send OCLOSE" from S1.e to S3.w
                     67: arrow "obuf_empty ||" "write_failed/" "shutdown_write" "send OCLOSE" from S2.e to S4.w
                     68: arrow from S1.s to S2.n
                     69: box invis "rcvd IEOF/" "-" with .e at last arrow.c
                     70: arrow from S3.s to S4.n
                     71: box invis "rcvd IEOF/" "-" with .w at last arrow.c
                     72: ellipse wid .9*ellipsewid ht .9*ellipseht at S4
                     73: arrow "start" "" from S1.w+(-0.5,0) to S1.w
                     74: .PE
1.2       markus     75: .SH
                     76: Notes
                     77: .PP
                     78: The input buffer is filled with data from the socket
1.5       markus     79: (the socket represents the local consumer/producer of the
1.2       markus     80: forwarded channel).
1.3       markus     81: The data is then sent over the INPUT-end (transmit-end) of the channel to the
1.2       markus     82: remote peer.
1.3       markus     83: Data sent by the peer is received on the OUTPUT-end (receive-end),
1.2       markus     84: saved in the output buffer and written to the socket.
                     85: .PP
                     86: If the local protocol instance has forwarded all data on the
                     87: INPUT-end of the channel, it sends an IEOF message to the peer.
1.5       markus     88: If the peer receives the IEOF and has consumed all
1.2       markus     89: data he replies with an OCLOSE.
                     90: When the local instance receives the OCLOSE
                     91: he considers the INPUT-half of the channel closed.
                     92: The peer has his OUTOUT-half closed.
                     93: .PP
                     94: A channel can be deallocated by a protocol instance
                     95: if both the INPUT- and the OUTOUT-half on his
                     96: side of the channel are closed.
1.5       markus     97: Note that when an instance is unable to consume the
1.2       markus     98: received data, he is permitted to send an OCLOSE
                     99: before the matching IEOF is received.