[monitoring-plugins] check_dig: use +retry instead of +tries

[Jan Wagner]

    Module: monitoring-plugins
    Branch: upstream/pr/1431
    Commit: d6bfbe33082309459b0d8ce289769f123c8d2451
    Author: Christian Kujau <ckujau at users.noreply.github.com>
 Committer: Jan Wagner <waja at cyconet.org>
      Date: Thu Sep 22 13:34:25 2016 -0700
       URL: https://www.monitoring-plugins.org/repositories/monitoring-plugins/commit/?id=d6bfbe3

check_dig: use +retry instead of +tries

After upgrading from an Ubuntu/15.10 installation to 16.04, I noticed
that check_dig is always returning a WARNING:

$ /usr/lib/nagios/plugins/check_dig -l localhost -v
/usr/bin/dig   -p 53 @127.0.0.1 localhost A +tries=3 +time=6
Looking for: 'localhost'
DNS WARNING - 0.008 seconds response time (dig returned an error
status)|time=0.008274s;;;0.000000

The older Ubuntu installation got its check_dig from the
nagios-plugins-standard package[0] which did not include the +tries
option. The current Ubuntu version provides its check_dig from the
monitoring-plugins-standard package[1], which _does_ use the +tries
option that was introduced with df53473[2].

On my system, it so happens that /usr/bin/dig is provided not by the
(BIND) dnsutils package but by knot-dnsutils[3] from the Knot DNS
project. The Knot dig(1) command doesn't support the +tries option[4]
but does support +retry (which is also supported[5] by the BIND dig(1)
command).

One way to fix that would be for me to install the BIND dnsutils
package. But I did not want to do that: it's so much larger in size and
pulls in much more dependencies than the knot-dnsutils package.

The patch below changes check_dig to use +retry instead of +tries. Both
options are similar, but not the same:

 +retry - Sets the number of times to retry UDP queries to server
          to T instead of the default, 2. Unlike +tries, this does
          not include the initial query

As number_tries seems to be hard coded to 3, I've lowered DEFAULT_TRIES
to 2 so check_dig should behave as before (with +tries=3).

TL;DR: when using +retry instead of +tries, both ISC dig and Knot kdig are working with "check_dig -t".

[0] http://packages.ubuntu.com/wily/nagios-plugins-standard
[1] http://packages.ubuntu.com/xenial/monitoring-plugins-standard
[2] https://github.com/monitoring-plugins/monitoring-plugins/commit/df53473
[3] http://packages.ubuntu.com/xenial/knot-dnsutils
[4] https://knot.readthedocs.io/en/latest/man_kdig.html#notes
[5] https://ftp.isc.org/isc/bind9/cur/9.10/doc/arm/man.dig.html

Note: this has been sent to -devel in May already but only now I managed to create this pull-request.
> [PATCH] check_dig: use +retry instead of +tries
> https://www.monitoring-plugins.org/archive/devel/2016-May/010312.html

Signed-off-by: Christian Kujau <lists at nerdbynature.de>

---

 plugins/check_dig.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/plugins/check_dig.c b/plugins/check_dig.c
index da4f0de..e01cf3e 100644
--- a/plugins/check_dig.c
+++ b/plugins/check_dig.c
@@ -3,7 +3,7 @@
 * Monitoring check_dig plugin
 * 
 * License: GPL
-* Copyright (c) 2002-2008 Monitoring Plugins Development Team
+* Copyright (c) 2002-2016 Monitoring Plugins Development Team
 * 
 * Description:
 * 
@@ -33,7 +33,7 @@
  *  because on some architectures those strings are in non-writable memory */
 
 const char *progname = "check_dig";
-const char *copyright = "2002-2008";
+const char *copyright = "2002-2016";
 const char *email = "devel at monitoring-plugins.org";
 
 #include "common.h"