F9 - cups - windows shared printer

Craig White craigwhite at azapple.com
Sat Jul 26 15:53:19 UTC 2008

On Sat, 2008-07-26 at 19:08 +1000, Andy Eager wrote:
> OK, for anyone interested (and as a way of documenting the problem), I 
> finally got to the bottom of this issue.
> It has absolutely nothing to do with users, groups, cups authentication, 
> Firefox or much else discussed in this thread!!
> I was using ipp as the printing protocol to talk to the printer:- A 
> Konica-Minolta MC2450.
> ipp://printer_hostname:631/ipp
> Not sure whether the problem is with CUPS implementation of ipp or the 
> printer itself, but if I change to JetDirect 
> (socket://printer_hostname), then everything works just fine.
> Now for the gory details:
> * printers.conf is setup initially without the AuthInfoRequired line 
> (which is the same AuthInfoRequired none)
> * When I try to print I get the following:
>    E [25/Jul/2008:17:20:53 +1000] [Job 1] Unable to get job 1997 
> attributes (client-error-not-authorized)!
>    I [25/Jul/2008:17:20:53 +1000] Saving printers.conf...
>    E [25/Jul/2008:17:20:53 +1000] PID 5314 (/usr/lib/cups/backend/ipp) 
> stopped with status 2!
>    D [25/Jul/2008:17:20:53 +1000] [Job 1] File 0 is complete.
>    I [25/Jul/2008:17:20:53 +1000] [Job 1] Backend returned status 2 
> (authentication required)
> * When cupsd saves printers.conf, it decides (incorrectly) that 
> authentication is required and inserts the AuthInfoRequired negotiate 
> line into printers.conf
> For any cups developers reading this, here's the code that does this 
> from job.c: (which I believe is semantically incorrect)
> if ((attr = cupsGetOption("auth-info-required", num_attrs,  attrs)) != NULL)
>       {
>          cupsdLogMessage(CUPSD_LOG_ERROR, "WOULD BE SETTING attribute 
> %s", attr);
>          // cupsdSetAuthInfoRequired(job->printer, attr, NULL);
>         cupsdSetPrinterAttrs(job->printer);
>         cupsdSaveAllPrinters();
>       }
> The first line is me wanting to see this event in the log file
> The second line is me commenting out the change to AuthInfoRequired.
> When I run this modified version of cups, I still see same output in the 
> log file, but the job does print (as do any subsequent jobs) and there 
> is no change made to printers.conf.
> Anyway, that's the full story.
> I now know the anatomy of cups way more than I ever wanted to!
did you want to add that to the bugzilla entry I started or should I

also, for the record, I never set up the printer as ipp but only as a
connection to windows shared printer (smb://) but perhaps the code is
similar there


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