[JDEV] Bug in the SSL I/O layer + fix

[Thomas Muldowney]

Hrm.... is this against the latest cvs?  I can't reproduce this, but maybe
I'm doing something wrong.  Do you have a test script?  Just want to test it
out a bit before I commit a change.

--temas


----- Original Message -----
From: "Daniel Veillard" <veillard at redhat.com>
To: <jdev at jabber.org>
Sent: Thursday, January 17, 2002 8:00 AM
Subject: [JDEV] Bug in the SSL I/O layer + fix


> Symptoms:
>    a large write from an SSL client gets blocked/delayed for
>    a long time in jabberd.
>
> Bug:
>    the select() mechanism is not able to detect that there is some
>    data left in the SSL buffers
>
> Explanation:
>    The client sends a really large chunk of data (anything > 8KB will do)
>    The SSL decryption layer ends up generating an input buffer which
>    is larger than the read done by the mail loop following the select
>    (the read is limited to 8K and usually less due to the karma computing.
>    The main loop does the read which fills up the buffer, is then
>    passed to the parser, and return in select(). The fact that the
>    read() may not consume all data is usually not a problem because
>    the leftovers will retrigger the exit from select. But for SSL
>    (and any layer with an intermediate buffer) there may be data left,
>    and select won't detect it. The data simply stalls in the buffer
>    until something else triggers the read on that selector again.
>
> Fix:
>    The enclosed patch provides an approximation of the correct solution.
>    The SSL read simply checks that SSL_read() filled the input buffer
>    and if yes request the main loop to iterate over the read on that
>    selector. It might not be a complete solution since the read may
>    be exactly the size of the buffer. The best is to ask the SSL layer
>    if there is some data left at the end of SSL_read() but I didn't
>    found the right API for this. This should be fixed at the end of
>    _mio_ssl_read() by replacing "if (ret == count) {" with code asking
>    the SSL layer.
>
> Extra question:
>    Is there an easy way to simply disable all Karma checks ? Or change
>    them all to something more in line for distributed computing needs.
>
> Daniel
>
> --
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>