XSF Discussion - 2018-11-23

is it illegal to send a presence update to multiple joined MUCs using the same szanza id?

maybe

It is up to the originating entity whether the value of the 'id' attribute is unique only within its current stream or unique globally.

you’re fulfilling neither of those .. requirements .. in that case

But treating ids as unique in its own is bound to give you grief, so better take the addressing into account.

oh god who wrote that code? `if (packetID != null ? !packetID.equals(packet.packetID) : packet.packetID != null) {`

Oops

So I was just sending the same presence packet to multiple @to MUCs, to my own participant JID, but it turns out only to work randomly. And from the logs it seems to have uncovered another unrelated bug.

Oh my. You can't send-change-send the same Packet object in smack3.

I think there's an assumption that clients don't repeat stanza ids on outbound traffic, but can't find the reference. As a recipient, you probably want to associate with the sender and recipient address. I'm pretty sure there are a lot of exploitable/buggy implementations.

*especially* with MUC

the problem is that I give smack3 a reference to the Packet object, not a copy. So by changing the JID, all of the enqueued references are sent to the same JID

Haha

which explains why the MUC status update happens randomly in a subset of MUCs

That's a bad idea to try anyway

because race conditions between enqueue and send thread.

flow: does smack4 create a local copy of a Packet that you pass to sendPacket()?

Yeah, once you send a stanza, don't touch it. I'm many libraries and languages.

In

See, I was just trying to be smart and to re-use resources.

also, should I set the same priority for MUCs as for my normal presence, or just keep it at 0?

aioxmpp would behave the same

the nicest thing is, when I was debugging the user report, single-stepping through the code made the bug vanish.

but it also has a convenient way to duplicate a stanza, so...

oh, a heisenbug

No, presence to MUC is directed and you can do whatever

And I was short of telling the user they are crazy. After they provided logs, I got suspicious, because the 0198 logger told me the packet is not being counted, which should never happen after <enable/>

Ge0rG, no, that wouldn't be sensible, as you had to pay the copy operation for every sendStanza() whereas I'd assume only a minority calls would benefit from it

but Presence has a copy constructor

flow: not in smack3 ;)

yeah, I can't really comment on five year old code

flow: it might be a good idea then to add a @warning to the docs, telling to never submit the same Packet twice.

C++ has some sophisticated ownership management cruft around that. I don't think there is any way to enforce that in Java though

I'm not sure if it justifies a warning since it is common for sink like functions that you hand over ownership of the provided arguments, but a note to the javadoc sure can't hurt

it's not going to prevent people from doing what I did, leading to hard to debug issues. But after they realize what they did wrong, they'll see the message in the docs and feel even more ashamed.

hah

patches welcome ;)

I had to look up the semantics of Queue.contains() and single-step through Packet.equals() to be enlighted

Hey guys, I couldn't attend the meeting yesterday unfortunately, but congratulations to everyone and thank you very much Alex :)

Seve, congratulations to you, too :)

and congratulations to jonas’ as well!

thanks, but didn’t we have that yesterday or did I miss something? ;-)

jonas’: I think I didn't congratulate you specifically.

ah, well

User Mood?

`<happy xmlns='http://jabber.org/protocol/mood'/>`

<x xmlns="jabber:x:oob"><url>https://www.youtube.com/watch?v=ZbZSe6N_BXs</url></x>?

Lol ❌

jonas’: I'm disappointed in your taste of music.

(I also kind of had expected https://www.youtube.com/watch?v=DLzxrzFCyOs)

Ge0rG, who says that this is my taste of music?

jonas’: I considered it would be too meta if you implied that that was Seve's music taste.

no, I don’t know his music taste :)

I like human music

as opposed to computer-generated music?

what about music written by humans and performed by computers? (the 386dx project comes to mind)

It was a reference to a show called Rick and Morty :D https://www.youtube.com/watch?v=S1jWdeRKvvk

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