[nos-bbs] JNOS and FBBCMP (Version 1) - was JNOS (#define B2F) - fwding problem/disaster with *older* systems

Maiko Langelaar maiko at pcs.mb.ca
Thu Jan 20 12:00:22 EST 2011

Good morning,

Okay, I think I know what is going on here. If you look carefully in the
code, JNOS never did support B1F, only BF. Up until the B2F showed up, 
JNOS never had a problem dealing with xfbb or winfbb systems and others
that connected with a B1F in the their SID. Since JNOS never supported
it, it would always return the lower BF and everything was fine.

What happens if winfbb connects to a B2F enabled JNOS ? Well, it will
receive a SID that contains B2F. The winfbb system will send B1F back
to the JNOS and expect JNOS to continue with B1F. The problem here is
JNOS does NOT support B1F, it never did ! It ignores the '1', treating
the response as a plain old BF (FBBCMP version 0).

That becomes a problem. Version 1 has extra checksum and length info,
so sending Version 0 format to a system expecting Version 1 results in
the big mess mentioned in previous emails.

That is why I added the 'mbox nob2f option', to deal with systems that
are sending B1F SIDs to B2F enabled JNOS systems. In fact, I believe now
that if B1F is not supported, then JNOS should terminate the connection
at that point, since the lower denominator in the initial exchange is
simply not possible.

I hope that clears this up.

I will get this fixed, and add B1F support as soon as I can.

Also note, B2F forwarding between two JNOS 2.0 systems does not work
right now, messages are always rejected (FS -). I have a fix for this
already, but I have not put it into my development area yet - the fix
is quite trivial actually, and not a very serious bug.

Seeing two JNOS systems forwarding with FC proposals is kinda neat :)

If one of them is set to 'mbox fbb 2' then forwarding is fine.

Maiko Langelaar / VE4KLM

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