your mail

[Yavor G Georgiev]

Hello Markus,

Thursday, November 08, 2001, 12:25:19 PM, you wrote:

MF> hi,

MF> if i understand you correctly your problem is that you and i disagree
MF> about what 'window size' means and what data/length is included in the
MF> 'window'

MF> if i send a
MF>         byte      SSH_MSG_CHANNEL_DATA
MF>         uint32    recipient channel
MF>         string    data
MF> packet in OpenSSH, i count only the actual size of the data,
MF> and not the size of the complete packet as sent on the wire.

MF> draft-ietf-secsh-connect-11.txt says:
MF>         "The window size is decremented by the amount of data sent."

MF> i don't think that the additional 1+4+4 bytes (byte,uint32,uint32)
MF> should be included in the window size counter. but i could be wrong.
MF> perhaps the draft is ambiguous about this.

MF> what do other implementations do?

MF> i think that only the size of the actual 'payload' data should be
MF> included in the window size, because you usually send
MF> SSH_MSG_CHANNEL_WINDOW_ADJUST messages if you have consumed the data
MF> (e.g. written the data to a socket).

MF> when forwarding/consuming the data received on a channel, OpenSSH does
MF> no longer know over how many packets this data was originally
MF> distributed. so only the length of the payload, the amount of data
MF> written to the 'consumer-socket' can be used to caculate the size for
MF> SSH_MSG_CHANNEL_WINDOW_ADJUST.

MF> -m

Yes you got me right.
I assume the data to be the last part in the following example packet:
         byte      SSH_MSG_CHANNEL_DATA
         uint32    recipient channel
         string    data
the one that is type string, which includes 4 more bytes for the
length.
You asked me about other implementations. I have made many tests with
the PuTTY client. It sends window adjustment after every
recieved packet. The value of the adjustment is calculated as the data
field not the payload of the data.
 I am totally agreed with you that the draft is ambigious. Can we get
 some advice from the draft guys - what had they meant ?
 
 ---
Best regards,
 Yavor                            mailto:yasho at rambler.bg