Are you checking the open source code for tn5250 or tn5250j for helpful

On Wed, Jun 13, 2018 at 10:32 AM, James H. H. Lampert <
jamesl@xxxxxxxxxxxxxxxxx> wrote:

We have a terminal emulator problem.

On a handful of hosts, our Java-based TN5250 emulator has a chronic
problem of sporadic crashing.

On the host where that happens the most, it happens both with and without
SSL. The owners of the host have filed a PMR, and the IBM analyst swears up
and down that we are sending 200kB (and larger) packets that are causing
buffer overruns.

We have data stream capture and buffer-dump diagnostics built into the
emulator, and we have yet to find a single case in which the last thing we
sent before the crash (or indeed, anything we sent) was even as much as
16kB, at least as an RFC 1205/2877 TN5250 data stream passed to the socket.

Moreover, according to the traces and dumps on our end, there are at least
as many cases in which the last traffic through the socket was sent FROM
the host TO the emulator.

Almost from the beginning, it has looked to me like some sort of network
issue. Except that IBM's own emulator is apparently immune.

It's driving me crazy. Every time I see new email from the customer with
the open PMR, my blood starts to boil. And none of the Google searches I've
tried, looking for some sort of list-server or board for help diagnosing
Java SSL problems have turned up anything even vaguely relevant (most seem
to be concerned either with certs, or with HTTPS, or both.

When we establish secure connection, we start with a static
SSLSocketFactory. This is instantiated using an SSLContext that has a very
basic TrustManager. We then, whenever a new secured socket is needed, get
the socket from the factory with a "createSocket(adr, port)" method call.
Perfectly straightforward, and it works just fine on the overwhelming
majority of hosts.

I don't understand what could make the Telnet server think it was getting
a 200kB packet, when I can find no evidence that we've ever sent anything
remotely that big.

This is the Java Programming on and around the IBM i (JAVA400-L) mailing
To post a message email: JAVA400-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
or email: JAVA400-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives

As an Amazon Associate we earn from qualifying purchases.

This thread ...


Follow On AppleNews
Return to Archive home page | Return to MIDRANGE.COM home page

This mailing list archive is Copyright 1997-2022 by and David Gibbs as a compilation work. Use of the archive is restricted to research of a business or technical nature. Any other uses are prohibited. Full details are available on our policy page. If you have questions about this, please contact [javascript protected email address].

Operating expenses for this site are earned using the Amazon Associate program and Google Adsense.