[RFR] 8184328: JDK8u131 socketRead0 hang at SSL read

Rob McKenna rob.mckenna at oracle.com
Fri Sep 15 14:00:25 UTC 2017


When we call close() on the SSLSocket that calls close() on the
underlying java Socket which closes the native socket.

    -Rob

On 13/09/17 04:09, Xuelei Fan wrote:
> It's a little bit complicated for layered SSL connections.  Application can
> build a SSL connection on existing socket (we call it layered SSL
> connections).  The problem scenarios make look like:
> 1. open a socket for applications.
> 2. established a SSL connection on the existing socket.
> 3. close the SSL connection, but leaving data in the socket.
> 4. establish another SSL connection on the socket, as the existing data in
> the socket, the connection cannot be established.
> 5. establish another app connection on the socket, as the existing data in
> the socket, the connection cannot be established.
> ....
> 
> Timeout happens even on very high speed network. If a timeout happens and
> the SSL connection is not closed gracefully, and then the following
> applications breaks.  IMHO, we need to take care of the case.
> 
> Xuelei
> 
> On 9/13/2017 1:06 PM, Chris Hegarty wrote:
> >Xuelei,
> >
> >Without diving deeper into this issue, Rob’s suggested approach seems reasonable to me, and better than existing out-of-the-box behaviour. I’m not sure what issues you are thinking of, with using the read timeout in combination with a retry mechanism, in this manner? If the network is so slow, surely there will be other issues with connecting and reading, why is closing any different.
> >
> >-Chris.
> >
> >>On 13 Sep 2017, at 16:52, Rob McKenna <rob.mckenna at oracle.com> wrote:
> >>
> >>Hi Xuelei,
> >>
> >>This behaviour is already exposed via the autoclose boolean in:
> >>
> >>https://docs.oracle.com/javase/8/docs/api/javax/net/ssl/SSLSocketFactory.html#createSocket-java.net.Socket-java.io.InputStream-boolean-
> >>
> >>My position would be that allowing 5 retries allows us to say with some
> >>confidence that we're not going to get a close_notify from the server.
> >>If this is the case I think its reasonable to close the connection.
> >>
> >>W.r.t. a separate timeout, the underlying mechanics of a close already
> >>depend on the readTimeout in this situation. (waiting on a close_notify
> >>requires performing a read so the read timeout makes sense in this
> >>context) I'm happy to alter that but I think that the combination of
> >>a timeout and a retry count is straightforward and lower impact.
> >>
> >>In my opinion the default behaviour of potentially hanging indefinitely
> >>is worse than the alternative here. (bearing in mind that we are closing
> >>the underlying socket)
> >>
> >>I'll file a CSR as soon as we settle on the direction this fix will
> >>take.
> >>
> >>    -Rob
> >>
> >>On 13/09/17 05:52, Xuelei Fan wrote:
> >>>In theory, there are intermittent compatibility problems as this update may
> >>>not close the SSL connection over the existing socket layer gracefully, even
> >>>for high speed networking environments, while the underlying socket is
> >>>alive.  The impact could be serious in some environment.
> >>>
> >>>For safe, I may suggest turn this countermeasure off by default.  And
> >>>providing options to turn on this countermeasure:
> >>>1. Close the SSL connection gracefully by default; or
> >>>2. Close the SSL connection after a timeout.
> >>>
> >>>It's hardly to say 5 times receiving timeout is better/safer than timeout
> >>>once in this context.  As you have already had a system property to control,
> >>>you may be able to use options other than the customized socket receiving
> >>>timeout, so that the closing timeout is not mixed/confused/dependent on/with
> >>>the receiving timeout.
> >>>
> >>>Put all together:
> >>>1. define a closing timeout, for example "jdk.tls.waitForClose".
> >>>2. the property default value is zero, no behavior changes.
> >>>3. applications can set positive milliseconds value for the property. The
> >>>SSL connection will be closed in the set milliseconds (or about the maximum
> >>>value between SO_TIMEOUT and closing timeout), the connection is not grant
> >>>to be gracefully.
> >>>
> >>>What do you think?
> >>>
> >>>BTW, please file a CSR as this update is introducing an external system
> >>>property.
> >>>
> >>>Thanks,
> >>>Xuelei
> >>>
> >>>On 9/11/2017 3:29 PM, Rob McKenna wrote:
> >>>>Hi folks,
> >>>>
> >>>>In high latency environments a client SSLSocket with autoClose set to false
> >>>>can hang indefinitely if it does not correctly recieve a close_notify
> >>>>from the server.
> >>>>
> >>>>In order to rectify this situation I would like to suggest that we
> >>>>implement an integer JDK property (jdk.tls.closeRetries) which instructs
> >>>>waitForClose to attempt the close no more times than the value of the
> >>>>property. I would also suggest that 5 is a reasonable default.
> >>>>
> >>>>Note: each attempt times out based on the value of
> >>>>Socket.setSoTimeout(int timeout).
> >>>>
> >>>>Also, the behaviour here is similar to that of waitForClose() when
> >>>>autoClose is set to true, less the retries.
> >>>>
> >>>>http://cr.openjdk.java.net/~robm/8184328/webrev.01/
> >>>>
> >>>>    -Rob
> >>>>
> >


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