2 OpenSSH Channel Close Protocol 2.0 Implementation
4 Channel Input State Diagram
9 ellipsewid=s*ellipsewid
12 S1: ellipse "INPUT" "OPEN"
13 move right 2*l from last ellipse.e
15 move down l from last ellipse.s
16 S4: ellipse "INPUT" "CLOSED"
17 move down l from 1st ellipse.s
18 S2: ellipse "INPUT" "WAIT" "DRAIN"
19 arrow from S1.e to S4.n
20 box invis "rcvd CLOSE/" "shutdown_read" with .sw at last arrow.c
21 arrow "ibuf_empty ||" "rcvd CLOSE/" "send EOF" "" from S2.e to S4.w
22 arrow from S1.s to S2.n
23 box invis "read_failed/" "shutdown_read" with .e at last arrow.c
24 ellipse wid .9*ellipsewid ht .9*ellipseht at S4
25 arrow "start" "" from S1.w+(-0.5,0) to S1.w
28 Channel Output State Diagram
30 S1: ellipse "OUTPUT" "OPEN"
31 move right 2*l from last ellipse.e
33 move down l from last ellipse.s
34 S4: ellipse "OUTPUT" "CLOSED"
35 move down l from 1st ellipse.s
36 S2: ellipse "OUTPUT" "WAIT" "DRAIN"
37 arrow from S1.e to S4.n
38 box invis "write_failed/" "shutdown_write" with .sw at last arrow.c
39 arrow "obuf_empty ||" "write_failed/" "shutdown_write" "" from S2.e to S4.w
40 arrow from S1.s to S2.n
41 box invis "rcvd EOF ||" "rcvd CLOSE/" "-" with .e at last arrow.c
42 ellipse wid .9*ellipsewid ht .9*ellipseht at S4
43 arrow "start" "" from S1.w+(-0.5,0) to S1.w
48 The input buffer is filled with data from the socket
49 (the socket represents the local consumer/producer of the
51 The data is then sent over the INPUT-end (transmit-end) of the channel to the
53 Data sent by the peer is received on the OUTPUT-end (receive-end),
54 saved in the output buffer and written to the socket.
56 If the local protocol instance has forwarded all data on the
57 INPUT-end of the channel, it sends an EOF message to the peer.
59 A CLOSE message is sent to the peer if
60 both the INPUT- and the OUTOUT-half of the local
61 end of the channel are closed.
63 The channel can be deallocated by a protocol instance
64 if a CLOSE message he been both sent and received.