[Telepathy] Fw: [Standards] XEP-0174: TXT record format

Alban Crequy alban.crequy at collabora.co.uk
Mon Oct 20 11:49:50 PDT 2008


Does telepathy-salut publish its TXT records with avahi correctly? I
see multiple TXT records with avahi-discover, but I am not sure to read
the output correctly.


----- Message Transféré -----

Date: Mon, 20 Oct 2008 10:06:44 -0600
De: Peter Saint-Andre <stpeter at stpeter.im>
À: XMPP Extension Discussion List <standards at xmpp.org>
Sujet: [Standards] XEP-0174: TXT record format

While reviewing draft-cheshire-dnsext-dns-sd this morning, I think I
found a serious error in the documentation for the _presence._tcp
service, as defined in XEP-0174:


XEP-0174 says that a compliant client publishes *multiple* TXT records,
one for each parameter (e.g., one record for txtvers, one for 1st name,
one for email address, and so on). However, draft-cheshire-dnsext-dns-sd
says that an entity publishes *one* TXT with multiple key-value pairs,
where the name of the TXT record is the same as the name of the SRV
record and the value of the TXT record is a binary object that contains
one or more strings, where each string is (usually) a key-value pair and
the strings are separated by a single length byte that specifies the
length of the key-value pair.

So currently XEP-0174 says that in our hypothetical example the client
would publish the following TXT records:

juliet IN TXT "txtvers=1"
juliet IN TXT "1st=Juliet"
juliet IN TXT "email=juliet at capulet.lit"
juliet IN TXT "hash=sha-1"
juliet IN TXT "jid=juliet at capulet.lit"
juliet IN TXT "last=Capulet"
juliet IN TXT "msg=Hanging out downtown"
juliet IN TXT "nick=JuliC"
juliet IN TXT "node=http://www.adiumx.com"
juliet IN TXT "phsh=a3839614e1a382bcfebbcf20464f519e81770813"
juliet IN TXT "port.p2pj=5562"
juliet IN TXT "status=avail"
juliet IN TXT "vc=CA!"
juliet IN TXT "ver=66/0NaeaBKkwk85efJTGmU47vXI="

However, if I'm reading draft-cheshire-dnsext-dns-sd correctly then it
seems that the client would publish a single TXT record, as follows
(line breaks provided for readability).

juliet at pronto._presence._tcp.local. TXT "
0x1Eemail=juliet at capulet.lit
0x1Cjid=juliet at capulet.lit
0x12msg=Hanging out downtown

If I'm right, this is a fairly serious spec bug.


Peter Saint-Andre

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