Subject: Re: Packet drop on full socket problem

Re: Packet drop on full socket problem

From: Daniel Stenberg <>
Date: Thu, 7 Oct 2010 11:30:17 +0200 (CEST)

On Wed, 6 Oct 2010, Daniel Stenberg wrote:

> I'll get myself a dropbear install and see if I can repeat this. Is
> uploading data with a 128K buffer enough to trigger it? Like with the
> sftp_write_nonblock.c example?

I installed dropbear and I managed to repeat a problem when uploading to it,
but it was due to dropbear's maximum SSH packet size limit at 32768 bytes.
Once I fixed that I could upload fine using the scp_write_nonblock example,
which uses 100K buffers. I tried dropbear with default window (24576) and with
200000, both worked fine. (My change is pushed, together with a bunch of other
cleanups in the error code department.)

To fix the problem, I had to once again do a rather lame fix in
_libssh2_channel_write() to limit the amount of data it passes on to
transport_write(). I'm slowly starting to build up motivation for myself to
start working on a rather major internal overhaul regarding how we deal with
buffers/packets when sending data. More about that later on.

Received on 2010-10-07