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1 | .\" $OpenBSD: nchan2.ms,v 1.2 2001/10/03 10:05:57 markus Exp $ | |
2 | .\" | |
3 | .\" Copyright (c) 2000 Markus Friedl. All rights reserved. | |
4 | .\" | |
5 | .\" Redistribution and use in source and binary forms, with or without | |
6 | .\" modification, are permitted provided that the following conditions | |
7 | .\" are met: | |
8 | .\" 1. Redistributions of source code must retain the above copyright | |
9 | .\" notice, this list of conditions and the following disclaimer. | |
10 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
11 | .\" notice, this list of conditions and the following disclaimer in the | |
12 | .\" documentation and/or other materials provided with the distribution. | |
13 | .\" | |
14 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
15 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
16 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
17 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
18 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
19 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
20 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
21 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
22 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
23 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
24 | .\" | |
25 | .TL | |
26 | OpenSSH Channel Close Protocol 2.0 Implementation | |
27 | .SH | |
28 | Channel Input State Diagram | |
29 | .PS | |
30 | reset | |
31 | l=1 | |
32 | s=1.2 | |
33 | ellipsewid=s*ellipsewid | |
34 | boxwid=s*boxwid | |
35 | ellipseht=s*ellipseht | |
36 | S1: ellipse "INPUT" "OPEN" | |
37 | move right 2*l from last ellipse.e | |
38 | S3: ellipse invis | |
39 | move down l from last ellipse.s | |
40 | S4: ellipse "INPUT" "CLOSED" | |
41 | move down l from 1st ellipse.s | |
42 | S2: ellipse "INPUT" "WAIT" "DRAIN" | |
43 | arrow from S1.e to S4.n | |
44 | box invis "rcvd CLOSE/" "shutdown_read" with .sw at last arrow.c | |
45 | arrow "ibuf_empty ||" "rcvd CLOSE/" "send EOF" "" from S2.e to S4.w | |
46 | arrow from S1.s to S2.n | |
47 | box invis "read_failed/" "shutdown_read" with .e at last arrow.c | |
48 | ellipse wid .9*ellipsewid ht .9*ellipseht at S4 | |
49 | arrow "start" "" from S1.w+(-0.5,0) to S1.w | |
50 | .PE | |
51 | .SH | |
52 | Channel Output State Diagram | |
53 | .PS | |
54 | S1: ellipse "OUTPUT" "OPEN" | |
55 | move right 2*l from last ellipse.e | |
56 | S3: ellipse invis | |
57 | move down l from last ellipse.s | |
58 | S4: ellipse "OUTPUT" "CLOSED" | |
59 | move down l from 1st ellipse.s | |
60 | S2: ellipse "OUTPUT" "WAIT" "DRAIN" | |
61 | arrow from S1.e to S4.n | |
62 | box invis "write_failed/" "shutdown_write" with .sw at last arrow.c | |
63 | arrow "obuf_empty ||" "write_failed/" "shutdown_write" "" from S2.e to S4.w | |
64 | arrow from S1.s to S2.n | |
65 | box invis "rcvd EOF ||" "rcvd CLOSE/" "-" with .e at last arrow.c | |
66 | ellipse wid .9*ellipsewid ht .9*ellipseht at S4 | |
67 | arrow "start" "" from S1.w+(-0.5,0) to S1.w | |
68 | .PE | |
69 | .SH | |
70 | Notes | |
71 | .PP | |
72 | The input buffer is filled with data from the socket | |
73 | (the socket represents the local consumer/producer of the | |
74 | forwarded channel). | |
75 | The data is then sent over the INPUT-end (transmit-end) of the channel to the | |
76 | remote peer. | |
77 | Data sent by the peer is received on the OUTPUT-end (receive-end), | |
78 | saved in the output buffer and written to the socket. | |
79 | .PP | |
80 | If the local protocol instance has forwarded all data on the | |
81 | INPUT-end of the channel, it sends an EOF message to the peer. | |
82 | .PP | |
83 | A CLOSE message is sent to the peer if | |
84 | both the INPUT- and the OUTOUT-half of the local | |
85 | end of the channel are closed. | |
86 | .PP | |
87 | The channel can be deallocated by a protocol instance | |
88 | if a CLOSE message he been both sent and received. |