[monitoring-plugins] check_dig: patch to make dig honor -t option

Git Repository git at monitoring-plugins.org
Thu Jan 30 12:10:07 CET 2014

 Module: monitoring-plugins
 Branch: master
 Commit: df53473d03783ef853465c80162758bb6ee403c7
 Author: Jan Wagner <waja at cyconet.org>
   Date: Thu Jan 30 09:35:41 2014 +0100
    URL: https://www.monitoring-plugins.org/repositories/monitoring-plugins/commit/?id=df53473

check_dig: patch to make dig honor -t option

When a timeout value is specified with the -t option, dig will sometimes
timeout before the timer is actually reached.

The problem occurs because the check_dig plugin does not pass the specified
timeout value to dig, leaving dig to timeout with it's default value which
seems to be around 10-15seconds.

To reproduce:
time ./check_dig -H -l www.google.com -t 30

It will not run for 30secs, which is the expected behaviour.

The following will work, because the timeout is less than the default dig
timeout, so the plugin cancels the dig command:
time ./check_dig -H -l www.google.com -t 2

This fix passes the timeout value to dig, and sets the number of retries which tends to vary from system to system by default.

Closes #1168


 THANKS.in           |  1 +
 plugins/check_dig.c | 11 +++++++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/THANKS.in b/THANKS.in
index aef787c..2cfa54e 100644
--- a/THANKS.in
+++ b/THANKS.in
@@ -305,3 +305,4 @@ Geoff Oakham
 Tim Laszlo
 Stéphane Bortzmeyer
 Luca Corti
+Jethro Carr
diff --git a/plugins/check_dig.c b/plugins/check_dig.c
index 7575995..5638017 100644
--- a/plugins/check_dig.c
+++ b/plugins/check_dig.c
@@ -48,6 +48,8 @@ void print_usage (void);
 #define UNDEFINED 0
 #define DEFAULT_PORT 53
+#define DEFAULT_TRIES 3
 char *query_address = NULL;
 char *record_type = "A";
@@ -57,6 +59,7 @@ char *dig_args = "";
 char *query_transport = "";
 int verbose = FALSE;
 int server_port = DEFAULT_PORT;
+int number_tries = DEFAULT_TRIES;
 double warning_interval = UNDEFINED;
 double critical_interval = UNDEFINED;
 struct timeval tv;
@@ -72,6 +75,7 @@ main (int argc, char **argv)
   long microsec;
   double elapsed_time;
   int result = STATE_UNKNOWN;
+  timeout_interval = DEFAULT_TIMEOUT;
   setlocale (LC_ALL, "");
   bindtextdomain (PACKAGE, LOCALEDIR);
@@ -87,9 +91,12 @@ main (int argc, char **argv)
   if (process_arguments (argc, argv) == ERROR)
     usage_va(_("Could not parse arguments"));
+  /* dig applies the timeout to each try, so we need to work around this */
+  int timeout_interval_dig = ceil((double) timeout_interval / (double) number_tries);
   /* get the command to run */
-  xasprintf (&command_line, "%s %s @%s -p %d %s -t %s %s",
-            PATH_TO_DIG, query_transport, dns_server, server_port, query_address, record_type, dig_args);
+  xasprintf (&command_line, "%s @%s -p %d %s -t %s %s %s +tries=%d +time=%d",
+            PATH_TO_DIG, dns_server, server_port, query_address, record_type, dig_args, query_transport, number_tries, timeout_interval_dig);
   alarm (timeout_interval);
   gettimeofday (&tv, NULL);

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