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Commit | Line | Data |
---|---|---|
8efc0c15 | 1 | .TL |
2 | OpenSSH Channel Close Protocol 1.5 Implementation | |
3 | .SH | |
4 | Channel Input State Diagram | |
5 | .PS | |
6 | reset | |
7 | l=1 | |
8 | s=1.2 | |
9 | ellipsewid=s*ellipsewid | |
10 | boxwid=s*boxwid | |
11 | ellipseht=s*ellipseht | |
12 | S1: ellipse "INPUT" "OPEN" | |
13 | move right 2*l from last ellipse.e | |
14 | S4: ellipse "INPUT" "CLOSED" | |
15 | move down l from last ellipse.s | |
16 | S3: ellipse "INPUT" "WAIT" "OCLOSED" | |
17 | move down l from 1st ellipse.s | |
18 | S2: ellipse "INPUT" "WAIT" "DRAIN" | |
19 | arrow "" "rcvd OCLOSE/" "shutdown_read" "send IEOF" from S1.e to S4.w | |
20 | arrow "ibuf_empty/" "send IEOF" from S2.e to S3.w | |
21 | arrow from S1.s to S2.n | |
22 | box invis "read_failed/" "shutdown_read" with .e at last arrow.c | |
23 | arrow from S3.n to S4.s | |
24 | box invis "rcvd OCLOSE/" "-" with .w at last arrow.c | |
25 | ellipse wid .9*ellipsewid ht .9*ellipseht at S4 | |
26 | arrow "start" "" from S1.w+(-0.5,0) to S1.w | |
27 | .PE | |
28 | .SH | |
29 | Channel Output State Diagram | |
30 | .PS | |
31 | S1: ellipse "OUTPUT" "OPEN" | |
32 | move right 2*l from last ellipse.e | |
33 | S3: ellipse "OUTPUT" "WAIT" "IEOF" | |
34 | move down l from last ellipse.s | |
35 | S4: ellipse "OUTPUT" "CLOSED" | |
36 | move down l from 1st ellipse.s | |
37 | S2: ellipse "OUTPUT" "WAIT" "DRAIN" | |
38 | arrow "" "write_failed/" "shutdown_write" "send OCLOSE" from S1.e to S3.w | |
39 | arrow "obuf_empty ||" "write_failed/" "shutdown_write" "send OCLOSE" from S2.e to S4.w | |
40 | arrow from S1.s to S2.n | |
41 | box invis "rcvd IEOF/" "-" with .e at last arrow.c | |
42 | arrow from S3.s to S4.n | |
43 | box invis "rcvd IEOF/" "-" with .w at last arrow.c | |
44 | ellipse wid .9*ellipsewid ht .9*ellipseht at S4 | |
45 | arrow "start" "" from S1.w+(-0.5,0) to S1.w | |
46 | .PE | |
47 | .SH | |
48 | Notes | |
49 | .PP | |
50 | The input buffer is filled with data from the socket | |
51 | (the socket represents the local comsumer/producer of the | |
52 | forwarded channel). | |
53 | The data is then sent over the INPUT-end of the channel to the | |
54 | remote peer. | |
55 | Data sent by the peer is received on the OUTPUT-end, | |
56 | saved in the output buffer and written to the socket. | |
57 | .PP | |
58 | If the local protocol instance has forwarded all data on the | |
59 | INPUT-end of the channel, it sends an IEOF message to the peer. | |
60 | If the peer receives the IEOF and has comsumed all | |
61 | data he replies with an OCLOSE. | |
62 | When the local instance receives the OCLOSE | |
63 | he considers the INPUT-half of the channel closed. | |
64 | The peer has his OUTOUT-half closed. | |
65 | .PP | |
66 | A channel can be deallocated by a protocol instance | |
67 | if both the INPUT- and the OUTOUT-half on his | |
68 | side of the channel are closed. | |
69 | Note that when an instance is unable to comsume the | |
70 | received data, he is permitted to send an OCLOSE | |
71 | before the matching IEOF is received. |