[PD-dev] netsend/netreceive UDP ignore ECONNREFUSED
danomatika at gmail.com
Sun Mar 24 12:21:03 CET 2019
(sending again, on list)
One thing weird to me, is that the error not caught after nets end's send() call. It's caught later on by recv() at some point. So send() is not blocking on my system and/or we only receive that error when the IP subsystem "sends" as a reply to the application. Weird.
The man pages for send() on macOS don't list ECONNREFUSED in the error codes for the function...
> On Mar 23, 2019, at 12:59 AM, Christof Ressi <christof.ressi at gmx.at <mailto:christof.ressi at gmx.at>> wrote:
> ha! the [netsend -u] behaviour has always been a pet peave of mine. I've always wanted to fix this, but didn't find time yet... :-(
> personally, I would prefer solution nr. 1 (keep the socket open) as this is how most people expect UDP to work. I don't know how many patches rely on the current behaviour (apart from reconnecting after the socket has been closed). can you think of any sane use cases for this? (I'm only talking about UDP sockets of course).
> anyway, I'm already happy if there would be *some* way to keep the socket open, so a flag would be also fine.
> regarding improvements to [netsend], have you also considered this? https://github.com/pure-data/pure-data/issues/378 <https://github.com/pure-data/pure-data/issues/378>
> I can also contribute, but only after March.
> Gesendet: Freitag, 22. März 2019 um 22:56 Uhr
> Von: "Dan Wilcox" <danomatika at gmail.com <mailto:danomatika at gmail.com>>
> An: pd-dev <pd-dev at lists.iem.at <mailto:pd-dev at lists.iem.at>>
> Betreff: [PD-dev] netsend/netreceive UDP ignore ECONNREFUSED
> Howdy all,
> I've been making some proposal work for updates to netsend/netreceive.
> One issue is making UDP sending ignore connection refused errors. I have this working by catching the return value from recv():
> /* keep UDP alive */
> if (sys_sockerrno() == ECONNREFUSED && x->x_protocol == SOCK_DGRAM)
> (I added sys_sockerrno() to return the socket errno.)
> From my reading on the socket API, sending a UDP message conceptually shouldn't care about whether the receiver is there. However this is detected on a lower networking layer and propagated up to the application layer where it can be used or ignored.
> My questions are:
> 1. Should this ignore silently and not close the connection? I notice mrpeach [udpsend] seems to ignores the first try, then closes the socket on the next failure. However, I like keeping the socket as no errors are thrown and you can easily break than re-establish UDP sending/receiving. This works well with the [netsend] dst & source relays.
> 2. Should this be a creation argument, say -k? I imagine there are plenty of patches which expect the socket to be closed automatically and respond to a 0 from the connection outlet. On the other hand, as UDP is "connectionless" my thinking is that the conceptual "connection" of a UDP [netsend] (aka outlet) refers to the internal socket and not necessarily that the destination is reachable. With TCP, the connection state more obviously refers to 1-1 connection with the other side.
> Dan Wilcox
> @danomatika[http://twitter.com/danomatika <http://twitter.com/danomatika>]
> danomatika.com <http://danomatika.com/>[http://danomatika.com <http://danomatika.com/>]
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