[PD] ugly "already connected" errors

[Christof Ressi]

> The key is that you send something between deletion
> and recreation.

I do! 

> BTW, that's on Linux, maybe other platforms behave differently?

Could be, I'm currently on windows but I'll check on my linux and osx machines.

> Gesendet: Freitag, 25. Januar 2019 um 23:48 Uhr
> Von: "Roman Haefeli" <reduzent at gmail.com>
> An: pd-list at lists.iem.at
> Betreff: Re: [PD] ugly "already connected" errors
>
> On Fri, 2019-01-25 at 22:44 +0100, Christof Ressi wrote:
> > > From reading a bit more about protocols, particularly about ICMP
> > > [1], I
> > > think what happens is that the receiving host sends a ICMP error
> > > packet
> > > to the sending host, telling that the destination port is
> > > unreachable.
> > 
> > thanks, this might explain what happens. note, though, that this is
> > not required behaviour for a UDP socket (and I haven't encountered
> > this outside Pd), so I would rather make this optional (or add an
> > option to deactivate this). The reason is that sometimes you just
> > want to broadcast messages no matter if something is actually
> > listening and you don't want that the sender to shut down just
> > because the receiver is temporarily unavailable. of course you can
> > wrap each message in a [connect( [disconnect( pair, but I think it's
> > only an ugly workaround.
> 
> Yeah, I see how the current behavior is impractical. I'm just saying it
> is probably not a bug. 
> 
> > > can tell that the socket of [udpsend] is closed, because when you
> > > fire
> > > up the listening socket again, messages sent with [udpsend] still
> > > don't
> > > reach their destination.
> > 
> > I can't confirm this. I just tested with a pair of [udpsend] and
> > [udpreceive] (both iemlib and mrpeach) and I can change ports in
> > [udpreceive] or delete/recreate it without [udpsend] closing its
> > socket. only tested via localhost, though.
> 
> The key is that you send something between deletion and recreation.
> Otherwise you won't trigger an ICMP response. I tested also on
> localhost with a [udpreceive] and still get same behaviour I described.
> BTW, that's on Linux, maybe other platforms behave differently?
> 
> Roman
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