Problem with async-echo test

Volker Lendecke Volker.Lendecke at SerNet.DE
Wed Jul 27 02:57:42 MDT 2011

Hi, Metze and Andreas!

Running the async-echo smbtorture3 test I came across a
problem with the new dcerpc client libraries. That test
sends a dcerpc_echo_TestSleep_send and then after that some
cli_write_andx and cli_echo calls with the intention to put
the server to sleep and walking the async echo responder.
This does not work anymore, because the RPC request is only
sent out to the network after the cli_echo and cli_write&x
calls have been sent out. My impression is that this comes
via double-queueing via the tstream layer in the rpc
routines, but this impression might be wrong. I know this
used to work at some point. See the attached network trace
for the problem.

I know so far we have not given guarantees about the
ordering of requests in the async architecture, but my
assumption so far was that we maintain the ordering between
requests being sent to the smb client connection. If we now
have the client libraries freely re-order requests, we need
to augment them with something like barriers or so.


SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen
phone: +49-551-370000-0, fax: +49-551-370000-9
AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen
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