1999-10-27 03:42:43 +00:00
|
|
|
.TL
|
|
|
|
|
OpenSSH Channel Close Protocol 1.5 Implementation
|
|
|
|
|
.SH
|
|
|
|
|
Channel Input State Diagram
|
|
|
|
|
.PS
|
|
|
|
|
reset
|
|
|
|
|
l=1
|
|
|
|
|
s=1.2
|
|
|
|
|
ellipsewid=s*ellipsewid
|
|
|
|
|
boxwid=s*boxwid
|
|
|
|
|
ellipseht=s*ellipseht
|
|
|
|
|
S1: ellipse "INPUT" "OPEN"
|
|
|
|
|
move right 2*l from last ellipse.e
|
|
|
|
|
S4: ellipse "INPUT" "CLOSED"
|
|
|
|
|
move down l from last ellipse.s
|
|
|
|
|
S3: ellipse "INPUT" "WAIT" "OCLOSED"
|
|
|
|
|
move down l from 1st ellipse.s
|
|
|
|
|
S2: ellipse "INPUT" "WAIT" "DRAIN"
|
|
|
|
|
arrow "" "rcvd OCLOSE/" "shutdown_read" "send IEOF" from S1.e to S4.w
|
|
|
|
|
arrow "ibuf_empty/" "send IEOF" from S2.e to S3.w
|
|
|
|
|
arrow from S1.s to S2.n
|
|
|
|
|
box invis "read_failed/" "shutdown_read" with .e at last arrow.c
|
|
|
|
|
arrow from S3.n to S4.s
|
|
|
|
|
box invis "rcvd OCLOSE/" "-" with .w at last arrow.c
|
|
|
|
|
ellipse wid .9*ellipsewid ht .9*ellipseht at S4
|
|
|
|
|
arrow "start" "" from S1.w+(-0.5,0) to S1.w
|
|
|
|
|
.PE
|
|
|
|
|
.SH
|
|
|
|
|
Channel Output State Diagram
|
|
|
|
|
.PS
|
|
|
|
|
S1: ellipse "OUTPUT" "OPEN"
|
|
|
|
|
move right 2*l from last ellipse.e
|
|
|
|
|
S3: ellipse "OUTPUT" "WAIT" "IEOF"
|
|
|
|
|
move down l from last ellipse.s
|
|
|
|
|
S4: ellipse "OUTPUT" "CLOSED"
|
|
|
|
|
move down l from 1st ellipse.s
|
|
|
|
|
S2: ellipse "OUTPUT" "WAIT" "DRAIN"
|
|
|
|
|
arrow "" "write_failed/" "shutdown_write" "send OCLOSE" from S1.e to S3.w
|
|
|
|
|
arrow "obuf_empty ||" "write_failed/" "shutdown_write" "send OCLOSE" from S2.e to S4.w
|
|
|
|
|
arrow from S1.s to S2.n
|
|
|
|
|
box invis "rcvd IEOF/" "-" with .e at last arrow.c
|
|
|
|
|
arrow from S3.s to S4.n
|
|
|
|
|
box invis "rcvd IEOF/" "-" with .w at last arrow.c
|
|
|
|
|
ellipse wid .9*ellipsewid ht .9*ellipseht at S4
|
|
|
|
|
arrow "start" "" from S1.w+(-0.5,0) to S1.w
|
|
|
|
|
.PE
|
|
|
|
|
.SH
|
|
|
|
|
Notes
|
|
|
|
|
.PP
|
|
|
|
|
The input buffer is filled with data from the socket
|
|
|
|
|
(the socket represents the local comsumer/producer of the
|
|
|
|
|
forwarded channel).
|
1999-10-30 01:39:56 +00:00
|
|
|
The data is then sent over the INPUT-end (transmit-end) of the channel to the
|
1999-10-27 03:42:43 +00:00
|
|
|
remote peer.
|
1999-10-30 01:39:56 +00:00
|
|
|
Data sent by the peer is received on the OUTPUT-end (receive-end),
|
1999-10-27 03:42:43 +00:00
|
|
|
saved in the output buffer and written to the socket.
|
|
|
|
|
.PP
|
|
|
|
|
If the local protocol instance has forwarded all data on the
|
|
|
|
|
INPUT-end of the channel, it sends an IEOF message to the peer.
|
|
|
|
|
If the peer receives the IEOF and has comsumed all
|
|
|
|
|
data he replies with an OCLOSE.
|
|
|
|
|
When the local instance receives the OCLOSE
|
|
|
|
|
he considers the INPUT-half of the channel closed.
|
|
|
|
|
The peer has his OUTOUT-half closed.
|
|
|
|
|
.PP
|
|
|
|
|
A channel can be deallocated by a protocol instance
|
|
|
|
|
if both the INPUT- and the OUTOUT-half on his
|
|
|
|
|
side of the channel are closed.
|
|
|
|
|
Note that when an instance is unable to comsume the
|
|
|
|
|
received data, he is permitted to send an OCLOSE
|
|
|
|
|
before the matching IEOF is received.
|
