[cups.general] /usr/lib/cups/backend/dnssd failed (was: How to debug CUPS/dnssd/mdns)

[Marc Haber]

Hi Michael,

thanks for helping again.

With additional help from Debian, I was able to pin down my issue to a
bug in Debian's libavahi3-client 0.6.27-1
(http://bugs.debian.org/590760). I downgraded to 0.6.26 and I can
print again.

I am still interested in finding out how to debug this (to be able to
help myself in the future).

Michael Sweet <msweet at apple.com> wrote:
>On Aug 6, 2010, at 12:40 PM, Marc Haber wrote:
>> Michael Sweet <msweet at apple.com> wrote:
>>> "Unable to resolve URI" usually means that the service name you used in the device URI no longer exists.
>> 
>> Ah, that was valuable information. It would be helpful if the actual
>> URI would be mentioned in the log entry.
>
>The standard dnssd backend *does* log it, but Till's Debian version does not.

If you know where to look, the information is in the log
|D [13/Aug/2010:15:09:21 +0200] [Job 1731] envp[22]="DEVICE_URI=dnssd://C510-Sch8._pdl-datastream._tcp.local/
I just wasn't aware that the information is in the environment.


>>> You can use:
>>> 
>>>   dns-sd -L C510-Sch8 _pdl-datastream._tcp
>>> 
>>> to verify that the service name is right and:
>>> 
>>>   dns-sd -B _pdl-datastream._tcp
>>> 
>>> to manually browse.
>> 
>> Unfortunately, Debian sid doesn't have any program named dns-sd. Are
>> there alternatives to that tool?
>
>Debian normally comes with Avahi - avahi-resolve should replace "dns-sd -L" and avahi-browse should replace "dns-sd -B".

But how do I use these? I guess that I want to resolve a name to an
address, so avahi-resolve -n would be correct. But it doesn't work:

|$ avahi-resolve -n dnssd://C510-Sch8._pdl-datastream._tcp.local/
|Failed to resolve host name 'dnssd://C510-Sch8._pdl-datastream._tcp.local/': Timeout reached
|$ avahi-resolve -n C510-Sch8._pdl-datastream._tcp.local
|Failed to resolve host name 'C510-Sch8._pdl-datastream._tcp.local': Timeout reached
|$ avahi-resolve -n C510-Sch8
|Failed to create host name resolver: Invalid host name
|$ 

With the printer working again, the issue is now purely academic.

Greetings
Marc
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