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aa3378df | 1 | .\" |
2 | .\" Copyright (c) 1999 Markus Friedl. All rights reserved. | |
3 | .\" | |
4 | .\" Redistribution and use in source and binary forms, with or without | |
5 | .\" modification, are permitted provided that the following conditions | |
6 | .\" are met: | |
7 | .\" 1. Redistributions of source code must retain the above copyright | |
8 | .\" notice, this list of conditions and the following disclaimer. | |
9 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
10 | .\" notice, this list of conditions and the following disclaimer in the | |
11 | .\" documentation and/or other materials provided with the distribution. | |
12 | .\" 3. All advertising materials mentioning features or use of this software | |
13 | .\" must display the following acknowledgement: | |
14 | .\" This product includes software developed by Markus Friedl. | |
15 | .\" 4. The name of the author may not be used to endorse or promote products | |
16 | .\" derived from this software without specific prior written permission. | |
17 | .\" | |
18 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
19 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
20 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
21 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
22 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
23 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
24 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
25 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
26 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
27 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
28 | .\" | |
8efc0c15 | 29 | .TL |
30 | OpenSSH Channel Close Protocol 1.5 Implementation | |
31 | .SH | |
32 | Channel Input State Diagram | |
33 | .PS | |
34 | reset | |
35 | l=1 | |
36 | s=1.2 | |
37 | ellipsewid=s*ellipsewid | |
38 | boxwid=s*boxwid | |
39 | ellipseht=s*ellipseht | |
40 | S1: ellipse "INPUT" "OPEN" | |
41 | move right 2*l from last ellipse.e | |
42 | S4: ellipse "INPUT" "CLOSED" | |
43 | move down l from last ellipse.s | |
44 | S3: ellipse "INPUT" "WAIT" "OCLOSED" | |
45 | move down l from 1st ellipse.s | |
46 | S2: ellipse "INPUT" "WAIT" "DRAIN" | |
47 | arrow "" "rcvd OCLOSE/" "shutdown_read" "send IEOF" from S1.e to S4.w | |
48 | arrow "ibuf_empty/" "send IEOF" from S2.e to S3.w | |
49 | arrow from S1.s to S2.n | |
50 | box invis "read_failed/" "shutdown_read" with .e at last arrow.c | |
51 | arrow from S3.n to S4.s | |
52 | box invis "rcvd OCLOSE/" "-" with .w at last arrow.c | |
53 | ellipse wid .9*ellipsewid ht .9*ellipseht at S4 | |
54 | arrow "start" "" from S1.w+(-0.5,0) to S1.w | |
48e671d5 | 55 | arrow from S2.ne to S4.sw |
56 | box invis "rcvd OCLOSE/ " with .e at last arrow.c | |
57 | box invis " send IEOF" with .w at last arrow.c | |
8efc0c15 | 58 | .PE |
59 | .SH | |
60 | Channel Output State Diagram | |
61 | .PS | |
62 | S1: ellipse "OUTPUT" "OPEN" | |
63 | move right 2*l from last ellipse.e | |
64 | S3: ellipse "OUTPUT" "WAIT" "IEOF" | |
65 | move down l from last ellipse.s | |
66 | S4: ellipse "OUTPUT" "CLOSED" | |
67 | move down l from 1st ellipse.s | |
68 | S2: ellipse "OUTPUT" "WAIT" "DRAIN" | |
69 | arrow "" "write_failed/" "shutdown_write" "send OCLOSE" from S1.e to S3.w | |
70 | arrow "obuf_empty ||" "write_failed/" "shutdown_write" "send OCLOSE" from S2.e to S4.w | |
71 | arrow from S1.s to S2.n | |
72 | box invis "rcvd IEOF/" "-" with .e at last arrow.c | |
73 | arrow from S3.s to S4.n | |
74 | box invis "rcvd IEOF/" "-" with .w at last arrow.c | |
75 | ellipse wid .9*ellipsewid ht .9*ellipseht at S4 | |
76 | arrow "start" "" from S1.w+(-0.5,0) to S1.w | |
77 | .PE | |
78 | .SH | |
79 | Notes | |
80 | .PP | |
81 | The input buffer is filled with data from the socket | |
48e671d5 | 82 | (the socket represents the local consumer/producer of the |
8efc0c15 | 83 | forwarded channel). |
69256d9d | 84 | The data is then sent over the INPUT-end (transmit-end) of the channel to the |
8efc0c15 | 85 | remote peer. |
69256d9d | 86 | Data sent by the peer is received on the OUTPUT-end (receive-end), |
8efc0c15 | 87 | saved in the output buffer and written to the socket. |
88 | .PP | |
89 | If the local protocol instance has forwarded all data on the | |
90 | INPUT-end of the channel, it sends an IEOF message to the peer. | |
48e671d5 | 91 | If the peer receives the IEOF and has consumed all |
8efc0c15 | 92 | data he replies with an OCLOSE. |
93 | When the local instance receives the OCLOSE | |
94 | he considers the INPUT-half of the channel closed. | |
95 | The peer has his OUTOUT-half closed. | |
96 | .PP | |
97 | A channel can be deallocated by a protocol instance | |
98 | if both the INPUT- and the OUTOUT-half on his | |
99 | side of the channel are closed. | |
48e671d5 | 100 | Note that when an instance is unable to consume the |
8efc0c15 | 101 | received data, he is permitted to send an OCLOSE |
102 | before the matching IEOF is received. |