[Standards-JIG] stream:error for dialback with no SASL support

Justin Karneges justin-keyword-jabber.093179 at affinix.com
Mon Jul 26 19:59:36 UTC 2004

On Monday 26 July 2004 12:19 pm, Matthias Wimmer wrote:
> > So you may never receive an xmlns:db on the incoming stream.  And,
> > technically, a SASL S2S connection can be mutually authenticated through
> > TLS and SASL EXTERNAL so the incoming and outgoing stream can be on the
> > same socket.
> I may be wrong, but it has been discussed (on the xmppwg list I think)
> if SASL streams can be bidirectional, and I thought the result was that
> they are unidirectional as well. I'll have to check XMPP core again for
> this.

You're right, all s2s streams are unidirectional for stanzas, whether dialback 
or SASL-based.  There was a fairly major discussion about this, ending with a 
phone call to me from one of the IETF chairs.  The bottom line is that s2s 
"could" have been bidirectional, but for legacy reasons it was decided that 
sticking to unidirectional for xmpp 1.0 was the safest bet.

From xmpp-core, section 4.2:

"In the context of server-to-server communications, a server MUST use one TCP 
connection for XML stanzas sent from the server to the peer and another TCP 
connection (initiated by the peer) for stanzas from the peer to the server, 
for a total of two TCP connections."


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