[Xastir] "UP" on QUERIES

[Tom Russo]

On Sat, May 26, 2018 at 03:01:40PM -0600, we recorded a bogon-computron collision of the <russo at bogodyn.org> flavor, containing:
> On Sat, May 26, 2018 at 08:01:57PM +0200, we recorded a bogon-computron collision of the <mlhpub at free.fr> flavor, containing:
> > Hi all,
> > 
> > Thanks Curt and Tom for explanations about capital letters and the 
> > perfect compliance with APRS specifications.
> > I have tried today with Cyril with 30 m Robust-Packet.
> > Juste a last question about this : if queries from RF interface are 
> > processed, the same from TCP/IP interface look ignored.
> 
> No, we respond to spec-compliant queries we receive from any interface.  
> I just tested it by sending my home Xastir station a directed query from a 
> laptop that had only a TCP/IP interface.  The query was answered Just Fine.
> 
> But it does appear that there is something up with how we preocess queries, 
> because I have seen that just trying to send a regular message (i.e. not
> one created by one of our directed query buttons in the station info dialog),
> it does not get processed as a query, but as a message (which is acked, but 
> does not generate the answer).  I also confirmed that ---- from the very
> same laptop where the "direct station query" worked perfectly, sending 
> "?APRSD" in a message didn't.  That's a little annoying.

Actually, I see this very clearly in the code of the "decode_message" function
in db.c.  We have this:

    if (!done && strlen(msg_id) == 0 && to_my_call) {   // Message for me (inclu
ding SSID check)
                                                        // but without message-I
D.
[...]
        if (len > 2
                && message[0] == '?'
                && port != -1   // Not from a log file
                && to_my_call) { // directed query (check SSID also)
            // Smallest query known is "?WX".
            if (debug_level & 1)
                fprintf(stderr,"Received a directed query\n");
            done = process_directed_query(call,path,message+1,from);
        }


[...]

Which clearly shows that we do NOT process directed queries if they have a
message id.  That's spec compliant, but it means that you must also be
able to *send* directed queries without message ids somehow.  Right now,
the ONLY way Xastir has to do that is via the handful of directed query
buttons in the station info dialog.  Which means you can only send directed
queries if the station you want to query has actually been heard from by
your station. 

So if you want to send queries to a station that you can't hear on RF,
you have to make sure your APRS-IS feed can get it --- i.e. by adding
that station's call sign to your filter so you receive all the packets
from that station.  Then you can just right-click the station icon and get
access to the station info dialog.

-- 
Tom Russo    KM5VY
Tijeras, NM  

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