[Python-Dev] ssl module, non-blocking sockets and asyncore integration

[Bill Janssen]

Ah, now I remember.  It seems that sometimes when SSL_ERROR_WANT_READ
was returned, things would block; that is, the "handle_read" method on
asyncore.dispatcher was never called again, so the SSLSocket.recv()
method was never re-called.  There are several levels of buffering going
on, and I never figured out just why that was.  This (very rare) re-call
of "read" is to handle that.

Bill

Bill Janssen <janssen at parc.com> wrote:

> Giampaolo Rodola' <gnewsg at gmail.com> wrote:
> 
> > In the meanwhile I noticed something in the ssl.py code which seems to
> > be wrong:
> > 
> >     def recv (self, buflen=1024, flags=0):
> >         if self._sslobj:
> >             if flags != 0:
> >                 raise ValueError(
> >                     "non-zero flags not allowed in calls to sendall()
> > on %s" %
> >                     self.__class__)
> >             while True:
> >                 try:
> >                     return self.read(buflen)
> >                 except SSLError, x:
> >                     if x.args[0] == SSL_ERROR_WANT_READ:
> >                         continue
> >                     else:
> >                         raise x
> >         else:
> >             return socket.recv(self, buflen, flags)
> > 
> > I don't know the low levels but that while statement which continues
> > in case of SSL_ERROR_WANT_READ seems to be wrong (blocking), at least
> > when dealing with non-blocking sockets. I think the proper way of
> > doing recv() here is letting SSL_ERROR_WANT_READ propagate and let the
> > upper application (e.g. asyncore) deal with it.
> 
> It's an interesting point.  I'm not sure the underlying code will ever
> raise this exception.  Please file a bug report to help us track this.
> 
> Thanks.
> 
> Bill
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