[PD-dev] netsend/netreceive UDP ignore ECONNREFUSED
danomatika at gmail.com
Fri Mar 22 22:56:52 CET 2019
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.
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