[aprssig] Is floating point telemetry allowed in APRS?

Heikki Hannikainen hessu at hes.iki.fi
Thu Mar 28 01:11:39 CDT 2013


On Wed, 27 Mar 2013, Lynn W. Deffenbaugh (Mr) wrote:

> Note also that the javAPRSSrvr t/t (type telemetry) filter will not pass any 
> out-of-spec telemetry packets like these with floating point values or any 
> that exceed 255.

To be precise, javAPRSSrvr 4.0 does not pass out-of-spec telemetry packets 
to filtered-port clients which have a t/t filter set. 3.15 is not so 
strict. Both do pass these packets to other servers and full-feed clients.

It's all good and OK if clients do not parse out-of-spec packets, but if 
some client actually *crashes* when seeing such a packet, it's a problem 
in that client software. Corrupted packets happen all the time, it's not 
OK to crash when a client sees something that it didn't quite expect. 
That's called a security vulnerability in other circles.

   - Hessu



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