[Nagiosplug-devel] [ nagiosplug-Support Requests-1043798 ] check_citrix issues

Stanley Hopcroft Stanley.Hopcroft at IPAustralia.Gov.AU
Mon Oct 11 17:35:41 CEST 2004

Dear Resistor,

I am writing to thank you for your letter and say,

On Sat, Oct 09, 2004 at 06:28:33PM -0700, SourceForge.net wrote:
> Category: None
> Group: None
> Status: Open
> Priority: 5
> Submitted By: resistor3672 (resistor3672)
> Assigned to: Nobody/Anonymous (nobody)
> Summary: check_citrix issues
> Initial Comment:
> I ran into these issues using the check_citrix plugin, so 
> I'll share them here in the hopes that they will allow the 
> continued development of the plugin and of the 
> excellent Nagios package. 
> Issue 1) Lots of applications to look for
> If one has a large number of apps to look for, one should 
> split the seach into multiple services and have each 
> service look for a subset. The danger is that the buffer 
> used to hold all the search string will overflow, and 
> Nagios 1.2 will seg fault. One can alternatively try 
> increasing the buffer size in the plugin, and use the -L 
> option, but even so I still hit the seg fault after a couple 
> of dozen apps. 

There are a number of issues here. 

1 It would be good to fix the SEGV in Nag 1.2

If you know gdb, inducing the fault and then getting a backtrace would 
help the developers fix the problem.

The backtrace can be posted to me, nag-developers or here (pref 

If you don't know gdb, but you are willing to help, please contact me 
privately for some instructions.

2 Thanks for pointing out the problem.

Would you mind posting an example of inducing it (the search string you 
are using).

Unfortunately, I have no access to a huge number of published apps but 
other check_citrix users may.

FWIW, this plugin has been made obsolescent by Citrix Metaframe XP which 
uses a completely different (XML browse service) method of locating the 
application serers.

> Issue 2) Lots of apps in the list
> The plugin returns the application list on errors. If this 
> list exceeds the default nagios return buffer, the plugin 
> will behave strangely. I had it returning an OK status in 
> nagios (green) and showing the "Failed: " string in 
> status information.  I assume this is due to a lack of 
> buffer error checking in Nagios (can that be fixed?).  I 
> simply removed the print statements that show the list 
> on errors, and while it is less informative, it still tells me 
> when an application is missing from the list. 

Good idea. Maybe an acceptable mod is 

1 first .. last application

2 first 100 characters of application list.

Which would suit better ?

For other reasons, I run Nag patched with MAX_PLUGIN_OUTPUTLENGTH (in 
common/objects.h) increased, and this helps with verbose plugins.

Actually, re-reading what you have said, it sounds more like plugin 
failure since Nag simply truncates excessive plugin output (for all 
plugins [so option 2 shouldn't be necessary] - the plugin output in 
base/checks.c is either copied with strncpy or an fgets(), of the size 
of the output buffer).

It might be good to wrap the plugin in a shell script (that appends 
the output to a file as well as writing to STDOUT) and see what it's up 

Does the plugin respond the same way (when it reports an error) from the 

Yours sincerely.

Stanley Hopcroft

Network specialist, IT Infrastructure
IP Australia
Ph: (02) 6283 3189  Fax: (02) 6281 1353
PO Box 200 Woden  ACT 2606

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