Missing '.' seperator in debugging output from backend/dnssd

[michaelrsweet]

Version: 1.7.3 CUPS.org User: pseudonomous

See ubuntu bug (cups 1.7.2):

https://bugs.launchpad.net/ubuntu/+source/cups/+bug/1334449?comments=all If for debugging purposes one reads the output from running:

/usr/lib/cups/backend/dnssd

at the command line, one will see statements like:

DEBUG: Found "Sales._ipp._tcpzeroconf.org"... DEBUG: Querying "Sales._ipp._tcp.zeroconf.org"... DEBUG: sent=0, count=1 DEBUG: Found "Stuart's Home AirPrint Printer._ipp._tcpzeroconf.org"... DEBUG: Found "3rd. Floor Copy Room._ipp._tcpzeroconf.org"... DEBUG: Found "Engineering._ipp._tcpzeroconf.org"... DEBUG: Found "Marketing._ipp._tcpzeroconf.org"...

The domain component is not separated from the 'protocol component' of the dns record.

I have been unable to get cups to work with non-local (I mean services that are not served up by mdns in the domain .local) dns-sd ipp printers. (using unicast dns, I have gotten this to work with cups on OS X 10.6). I kept getting a DNS error:

ERROR: DNS failure: NXDOMAIN

At first I believed this was because the dns name was being constructed incorrectly, but after reading the source, I believe the problem is unrelated.

It seems likely to me that there is actually a problem with doing unicast dns lookups with Avahi, however, because of the weird debugging output from backend/dnssd, one is misled to believe that cups is constructing the wrong dnsname to look up.

I have confirmed the bug exists in cups 1.7.3 on Arch Linux as well. It's trivial to fix, but I've included a patch anyways. This bug does not exist with the version of cups (1.4.7) shipped with OS X 10.6.8, I do not know if it exists on more recent versions of OS X, but I don't see any reason why the code should be platform specific.

It should be trivial to patch; patch is attached.

[michaelrsweet]

CUPS.org User: mike

The problem is that mDNSResponder includes a trailing "." on the regtype value while Avahi doesn't. So the correct fix is to make this some more conditional code... :/

[michaelrsweet]

CUPS.org User: mike

Fixed in Subversion repository.

[michaelrsweet]

"dnssd.c.patch":

--- dnssd.c 2014-06-25 17:00:48.447803109 -0500 +++ dnssd.c.orig 2014-06-25 16:44:59.739098716 -0500 @@ -924,7 +924,7 @@

• Yes, add the device... */
• fprintf(stderr, "DEBUG: Found \"%s.%s.%s\"...\n", serviceName, regtype,

• fprintf(stderr, "DEBUG: Found \"%s.%s%s\"...\n", serviceName, regtype, replyDomain);

  device = calloc(sizeof(cups_device_t), 1);

[michaelrsweet]

"str4444.patch":

Index: backend/dnssd.c

--- backend/dnssd.c (revision 11968) +++ backend/dnssd.c (working copy) @@ -1,33 +1,17 @@ /*

• "$Id$" *

  • * DNS-SD discovery backend for CUPS.
  • * DNS-SD discovery backend for CUPS.
  • * Copyright 2008-2012 by Apple Inc.
  • * Copyright 2008-2014 by Apple Inc.
  • * These coded instructions, statements, and computer programs are the
  • * property of Apple Inc. and are protected by Federal copyright
  • * law. Distribution and use rights are outlined in the file "LICENSE.txt"
  • * "LICENSE" which should have been included with this file. If this
  • * file is missing or damaged, see the license at "http://www.cups.org/".
  • * These coded instructions, statements, and computer programs are the
  • * property of Apple Inc. and are protected by Federal copyright
  • * law. Distribution and use rights are outlined in the file "LICENSE.txt"
  • * "LICENSE" which should have been included with this file. If this
  • * file is missing or damaged, see the license at "http://www.cups.org/".
  • * This file is subject to the Apple OS-Developed Software exception.
  • *
  • * Contents:
  • *
  • * main() - Browse for printers.
  • * browse_callback() - Browse devices.
  • * browse_local_callback() - Browse local devices.
  • * client_callback() - Avahi client callback function.
  • * compare_devices() - Compare two devices.
  • * exec_backend() - Execute the backend that corresponds to the
  • * resolved service name.
  • * device_type() - Get DNS-SD type enumeration from string.
  • * get_device() - Create or update a device.
  • * query_callback() - Process query data.
  • * find_device() - Find a device from its name and domain.
  • * sigterm_handler() - Handle termination signals.
  • * unquote() - Unquote a name string.
  • * This file is subject to the Apple OS-Developed Software exception. */

  /* @@ -924,8 +908,11 @@

  • Yes, add the device... */
• fprintf(stderr, "DEBUG: Found \"%s.%s%s\"...\n", serviceName, regtype,
• replyDomain); +#ifdef HAVE_DNSSD
• fprintf(stderr, "DEBUG: Found \"%s.%s%s\"...\n", serviceName, regtype, replyDomain); +#else /* HAVE_AVAHI */

• fprintf(stderr, "DEBUG: Found \"%s.%s.%s\"...\n", serviceName, regtype, replyDomain); +#endif /* HAVE_DNSSD */

  device = calloc(sizeof(cups_device_t), 1); device->name = strdup(serviceName);