[cups-devel] requested-attributes: IPP_TAG_NAME versus IPP_TAG_KEYWORD

[Johannes Meixner]

Hello Michael Sweet
and Till Kamppeter,

I noticed that in some (curently rare) cases
   ippAddStrings(... IPP_TAG_NAME, "requested-attributes" ...)
is used instead of the correct form
   ippAddStrings(... IPP_TAG_KEYWORD, "requested-attributes" ...)

See
https://lists.samba.org/archive/samba-technical/2003-January/026577.html
and
http://cups.org/pipermail/cups/2013-February/025818.html
and
https://cups.org/str.php?L4567

Because also Till Kamppeter had falsely used IPP_TAG_NAME
I fear there might be (much?) more software "out there"
where it is also used falsely.

I would like to find out if my fear is founded
or if it is only an unfortunate coincidence.

When it is used falsely in a request to the cupsd, it results that
only a small subset of values is returned in cupsd's response
which causes unexpected strange behaviour of the application
that uses it falsely in its request.

We (i.e. SUSE) discovered it in Samba that queries the cupsd for
print jobs (basically the same what lpstat/lpq do).

In Samba it had worked with 'IPP_TAG_NAME, "requested-attributes"'
at least up to CUPS version 1.3.9 that we have in SLES11 but
now it does no longer work with CUPS version 1.7.5 in SLES12.

Initially we thought "JobPrivateValues" made the difference but then
we found out that 'IPP_TAG_NAME, "requested-attributes"' was the
root cause (even with "JobPrivateValues none" the cupsd's response
contained only a small subset of the values that had worked before).

I wonder if perhaps 'IPP_TAG_NAME, "requested-attributes"' was correct
at a former time (I mean really correct - not just working by chance)
but I don't think so because even in very old CUPS there is everywhere
'IPP_TAG_KEYWORD, "requested-attributes"' except the one fault
in util.c (see https://cups.org/str.php?L4567).

I would like to know what change in CUPS 1.3.9 versus CUPS 1.7.5
makes 'IPP_TAG_NAME, "requested-attributes"' no longer work.

As far as we found out the 'IPP_TAG_NAME, "requested-attributes"'
in Samba came from Michael Sweet in 2003 according to
https://lists.samba.org/archive/samba-technical/2003-January/026577.html

What makes me a bit nervous is that in 2013 Till Kamppeter still
had used 'IPP_TAG_NAME, "requested-attributes"' which may indicate
that there is perhaps wrong documentation somewhere?


Kind Regards
Johannes Meixner
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