[cups-devel] IPP backend bug

[Michael Sweet]

Vadim,

The IPP backend just passes the data through.  The problem is more likely with your configuration.

If you are using printer sharing (and thus are using the IPP backend to send the print job to the server), you MUST NOT use the Gutenprint driver on the client system, otherwise you will have problems like this.


> On Oct 27, 2014, at 12:39 AM, Vadim A. Misbakh-Soloviov <mva at mva.name> wrote:
> 
> Hi there!
> I've discovered, that CUPS, starting from 1.6.2 (tested on 1.6.2, 1.6.3, 1.7 and 2.0) has some issue in 
> IPP backend.
> 
> When I using my printer (Epson Stylus TX210), or my parents one (TX410) via usb backend — it 
> works flawlessly.
> 
> But when I setup it as IPP (and other symlinked backends like http/https/ipps) even on the same 
> host (even ipp://localhost/ !) cups silently finishes jobs (like successfully completed), but don't 
> print anything. All, that it says in error log is:
> 
>>> E [22/Aug/2013:19:52:18 +0700] [Job 643] Invalid printer command "!
> 
> With exactly one double-qoute and exclamation mark.
> 
> After some debugging I discovered that:
> 
>>> I [22/Aug/2013:21:20:09 +0700] [Job 648] Started filter /usr/libexec/cups/filter/commandtoepson 
> (PID 3330)
>>> I [22/Aug/2013:21:20:09 +0700] [Job 648] Started backend /usr/libexec/cups/backend/ipps (PID 
> 3331)
>>> D [22/Aug/2013:21:20:14 +0700] Discarding unused job-progress event...
>>> D [22/Aug/2013:21:20:14 +0700] [Job 649] PID 3333 (/usr/libexec/cups/filter/gziptoany) exited with 
> no errors.
>>> E [22/Aug/2013:21:20:14 +0700] [Job 649] Invalid printer command "!
> 
> That was make me think, that error can be somewhere in compression and encryption, but 
> unfortunately even with force-disabled encryption and compression i get:
>>> D [22/Aug/2013:21:38:10 +0700] [Job 655] PID 6324 (/usr/libexec/cups/filter/commandtoepson) 
> exited with no errors.
>>> E [22/Aug/2013:21:38:10 +0700] [Job 655] Invalid printer command "!
> 
> Only once, after long debug session, I even get something more informative then quote-
> exclamationmark error:
>>> D [22/Aug/2013:21:48:44 +0700] [Job 663] Set job-printer-state-message to "Invalid printer 
> command "<1B>@<1B>(R<08>"!", current level=INFO
> 
> 
> I mostly debugged it on cups-1.6.3 (since, 1.6.2 has broken russian web-interface and don't wont to 
> work at all for me), but as I mentioned above, all newer versions affected too.
> When I downgraded to, for example, 1.5.2 and removed cups-filters package (filters was bubdled 
> at 1.5's time) and doesn't touch (!!!) gutenprint, conatining 'commandtoepson' filter — it start to 
> work fine again (but, it seems, every client should downgrade to 1.5 to work with it).
> 
> I'm sure it is not guttenprint fault, since same "commandtoepson" filter works like a charm 
> with USB backend on any version (including 2.0), and with IPP on <1.6. So, I bet, it is some broken 
> API in IPP backend, but I can't get exactly part.
> Can somebody confirm the issue and say me, if I should report that on bugtracker or stop and 
> discuss here?
> 
> -- 
> Best regards,
> mva
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_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair