[Standards-JIG] rfc3921bis, <iq><service-unavailable/>

Ian Paterson ian.paterson at clientside.co.uk
Sun Oct 22 13:43:34 UTC 2006

Section 8.1 of RFC3921bis (Inbound Stanzas) simply states that the 
server must "return a <service-unavailable/> stanza error". IMHO, to 
avoid presence leaks the document needs to specify the exact character 
string that the server MUST return. Otherwise it will be difficult for a 
client to pretend to an observant non-subscriber that it is offline (or 
that its user's account may not even exist).

I propose the following string for the error element:
<error type='cancel'><service-unavailable 
Note that there is no 'code' attribute or whitespace, and both attribute 
values are wrapped in single (not double) quotes.

The server needs to ensure that the rest of the stanza is also 
predictable. The attributes of the <iq/> element need to be in canonical 
order. The XML content of the stanza that triggered the error MUST be 
included without any changes whatsoever to the character string.

Alternatively the server could simply ensure that before forwarding a 
stanza on behalf of a connected client it MUST rewrite the contents of 
the stanza in the form that it would have generated itself. (Perhaps 
even adding or removing a 'code' attribute to the <error/> element!)

- Ian


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