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