[cups] CUPS 2.1.3 questions

[Michael Sweet]

Dmitry,

> On Apr 20, 2016, at 4:39 AM, Dmitry Voronin <carriingfate92 at yandex.ru> wrote:
> 
> Hello all.
> 
> 1. Question about Get-Ptinter-Attributes via CUPS API. 
> 
> I make a request for Get-Printer-Attributes and send to CUPS server. I get a response. Response contains many attributes with "name printer-uri-supported" with groupTag IPP_TAG_PRINTER.
> I supporse, that 1 attribute can contains many values (in documentation):

Yes, printer-uri-supported is a "1setOf uri" attribute, which means 1 or more values.  But there should only be a single instance of the printer-uri-supported attribute, regardless of the number of values.

> The Question: whether the attribute list contains attributes only with unique names?

No.

Some operations return multiple groups of attributes so (for example) you'll see multiple "job-name" attributes in the response to Get-Jobs.  Each group of attributes is separated by an xxx-group-tag on the wire, which shows up as an empty attribute in the list with a NULL name and group tag of IPP_TAG_ZERO.

For operations that only return a single group of attributes, you can assume that attribute names are unique within that group and can rely on the return value from ippFindAttribute.

> 2. Question about Send-Document operation.
> 
> I have printer with authenticated policy (see default cupsd.conf). As DefaultAuth I use Basic. When I send document for printering, the document is not print at printer. At log I see, that "No authenticated data provided" for Send-Document operation. Why? 

How are you sending your document?

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Michael Sweet, Senior Printing System Engineer