[jcifs] java.io.IOException: Failed to establish session

[Adam Morgan]

Thanks Mike.  Musta been a Friday thing. More to this... now that the exception is being passed on as expected we're seeing the underlying issue and this is my next query.  

We're doing some tests to simulate network connectivity disappearing.  Everything connects as expected initially.  Then we drop the network adapter on the windows server so that our client cannot connect (or will drop a current connection).  We then go into a reconnect loop until the adapter is brought back up.  At this point, if the period of disconnect is relatively short (ie a minute) the client will pick up where it left off.

An issue seems to arise when the disconnection is prolonged.  I cannot be certain of a more specific duration unfortunately.  When it is prolonged, even once the server is back up, the client falls into a state where it cannot connect.  I have debugged, and have tracked it down to SmbTransport.ssn139().  It does the readn() on line 196, then falls to line 211, case "NbtException.CALLED_NOT_PRESENT".  Resulting in an exception from line  230.

The server box is absolutely available at this time, there's no firewall issue, and if I restart the JVM, the client will reconnect.  Can u shed any light?  I can send u a tcpdump packet capture if this is helpful.

Thanks

Adam

-----Original Message-----
From: Michael B Allen [mailto:ioplex at gmail.com] 
Sent: Saturday, July 10, 2010 3:42 AM
To: Adam Morgan
Cc: jcifs at lists.samba.org
Subject: Re: [jcifs] java.io.IOException: Failed to establish session

On Fri, Jul 9, 2010 at 9:25 AM, Adam Morgan <adam.morgan at q1labs.com> wrote:
> Thank you for the response Mike.  However, I'm not sure this will fix my issue.  This will just log the exception to STDERR unless I'm mistaken.  Is there no way to pass the exception up the stack to my code?  Else there's no graceful way to handle the error.
>
> Thoughts?

Hi Adam,

The default log.level is 1 and of course you can direct the log to a
file. So the patch is correct. It will no longer clutter the console
or application logs.

As for the "way to handle the error", if you study Transport.java
closely you'll see that the exception is saved and then re-thrown in
connect() unless the error happens after the connect timeout has
expired in which case the calling thread will get a "Connection
timeout" exception instead. Then by the time the "Failed to establish
session" is thrown afterward, the caller will have moved on and so the
exception is just logged and discarded as trying to do otherwise would
be redundant.

Mike

>
> -----Original Message-----
> From: Michael B Allen [mailto:ioplex at gmail.com]
> Sent: Thursday, July 08, 2010 5:11 PM
> To: Adam Morgan
> Cc: jcifs at lists.samba.org
> Subject: Re: [jcifs] java.io.IOException: Failed to establish session
>
> Hi Adam,
>
> That is indeed a mistake. The code should read:
>
> 243                         if (log.level >= 2)
> 244                             ex0.printStackTrace(log);
>
> I have adjusted this in my local copy and it will be included in the
> next release.
>
> Thanks for the feedback.
>
> Mike
>
> On Wed, Jul 7, 2010 at 11:03 AM, Adam Morgan <adam.morgan at q1labs.com> wrote:
>> Hello
>>
>>
>>
>> I'm running into an issue related to network connectivity.  We've setup a
>> windows box with samba and are connecting successfully with a client.  We
>> have a script running on the windows box to periodically turn off the
>> network adapter.  This is resulting in an exception being written to STDOUT
>> by the jcifs library, but the issue is never elevated to our code so we
>> cannot handle it gracefully (ie try a reconnect).  We're not doing anything
>> funky with configuration, just using the API in vanilla mode.
>>
>>
>>
>> Here's the exception:
>>
>>
>>
>> java.io.IOException: Failed to establish session with
>> 0.0.0.0<00>/172.16.30.183
>>
>>     at jcifs.smb.SmbTransport.ssn139(SmbTransport.java:230)
>>
>>     at jcifs.smb.SmbTransport.negotiate(SmbTransport.java:247)
>>
>>     at jcifs.smb.SmbTransport.doConnect(SmbTransport.java:309)
>>
>>     at jcifs.util.transport.Transport.run(Transport.java:232)
>>
>>     at java.lang.Thread.run(Thread.java:619)
>>
>>
>>
>> I see in jcifs.util.transport.Transport, line 243, that the exception is
>> being printed to STDOUT.
>>
>>
>>
>> Can u explain why this exception isn't passed on up thru to the code that is
>> using the API so we can handle it gracefully?  I've seen other timeout
>> exceptions that DO get passed up the chain so what might be making this one
>> not get passed up?
>>
>>
>>
>> Thanks
>>
>>
>>
>> Adam
>
>
>
> --
> Michael B Allen
> Java Active Directory Integration
> http://www.ioplex.com/
>



-- 
Michael B Allen
Java Active Directory Integration
http://www.ioplex.com/