[sane-devel] saned/sanei net bug

[Johannes Berg]

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somehow saned/the sanei network layer seem to get buffering wrong.

For example, I send the following:

SANE_NET_INIT
SANE_NET_GET_DEVICES
SANE_NET_EXIT

If I don't wait for the result from SANE_NET_GET_DEVICES before sending
the control code for SANE_NET_EXIT, then the SANE_NET_EXIT code is
discarded.
I would assume that somewhere there's a buffering problem and the old
buffer is simply dropped when the direction is changed or something.

The following works:
(echo  -n -e \\00\\00\\00\\00\\00\\00\\00\\00\\00\\00\\00\\00 ;
sleep .1 ; echo -n -e \\00\\00\\x00\\x01 ; sleep 1 ;
echo -en \\x00\\x00\\x00\\x0A ) | nc localhost 6566 -q 1 | hd

while this doesn't:
(echo  -n -e \\00\\00\\00\\00\\00\\00\\00\\00\\00\\00\\00\\00 ;
sleep .1 ; echo -n -e \\00\\00\\x00\\x01\\x00\\x00\\x00\\x0A
)| nc localhost 6566 -q 1 | hd

I think this is extremely counter-intuitive. TCP never guarantees
message boundaries, so one wouldn't think that data is explicitly read
by the application but then discarded.

johannes

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