On Thu Dec 13 16:51:35 2007, Peter Saint-Andre wrote:
http://www1.ietf.org/mail-archive/web/simple/current/msg07579.html
Hmmm. So we're stripping forwarded messages... Yes, that's the one.
> I'm wondering if people think that a similar thing might affect
XMPP, if
> you change "relay" to "XMPP Server". Is it possible, potentially,
for
> Calin and Donald, by exchanging sufficient data sufficiently
slowly, to
> choke up an XMPP s2s link? And if so, what do we do about it?
Theoretically this *might* be a problem with in-band bytestreams
(XEP-0047), which in a way is similar to MSRP. But you could send
"large" stanzas using plain old XMPP, too, so I don't think it is
(theoretically) limited to IBB. However, whether this theoretical
problem has any practical significance is another question.
Well, you'd just need to send sufficient stanzas, and/or sufficient
data, enough to overwhelm Donald, whether on purpose or by accident.
In particular, using Rémi's options, I think that if an XMPP server
were
in this situation it:
1. would not put the s2s connection on hold -- that's crazy!
Right, with you there.
2. would not discard the stanza, especially not for IQ stanzas but
probably not for message stanzas either
Right, I don't think that's desirable.
3. would not queue the stanza for later delivery since the
recipient is
online and has an available resource
No, I think Rémi is describing buffering, which is going to happen
somewhere unless you outright refuse the stanza. The MSRP people have
decided this is the way to handle things, but ultimately, this
implies that an XMPP server has infinite storage (whether in RAM or
disk), with which to buffer.
4. would return an error to the sender (e.g.,
<recipient-unavailable/>)
But won't this mean, effectively, that messages and/or data are lost?
In this case, I'm assuming Donald is legitmate - if Donald is
deliberately throttling his c2s link, in order to create a DoS, then
we don't care, of course.
What we want to do here - I think - is throttle the sender, and only
start to reject stanzas if the throttling is ignored. (Perhaps
because it's unsupported).
> And perhaps more importantly, has anyone ever seen this in the
wild?
I have not seen this in the wild.
Well, that's something, then - it means we needn't rush to a solution.
Dave.
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