NSCA 2.7 not working in single-process mode (bug)

[Ethan Galstad]

Ton Voon wrote:
> 
> On 24 Jan 2007, at 16:36, Rudolf van der Leeden wrote:
> 
>> As of NSCA 2.6 up to NSCA CVS the nsca daemon is no longer running  
>> successfully in single-process mode (--single option).
>> I discovered this during my recent upgrade to the Nagios 2.7.
>>
>> The symptons have been described in earlier postings:
>>     nsca responds to exactly one client request and stops responding  
>> (while still running).
>> There is no solution execpt avoiding the --single mode and working  
>> with --inetd or --daemon mode instead, or using NSCA 2.5.
>>
>> I checked the source nsca.c and found a workaround:
>> Enable in the function "accept_connection" the following if statement  
>> again:
>>          /* REMOVED 04/03/2006 EG - already done in  
>> wait_for_connections() */
>>          /*
>>           if(mode==SINGLE_PROCESS_DAEMON)
>>                   register_read_handler(sock,accept_connection,NULL);
>>           */
>> The real problem seems to lie in the way pfds[i].events is maintained.
>> handle_events() clears it  ( pfds[i].events&=~POLLIN; ) and  
>> register_poll() sets it again in NSCA 2.5 because  
>> register_read_handler is called which in turn calls register_poll().
>> NSCA 2.7 does not call register_poll() and hence the fd is removed as  
>> events=0 (done at the end of handle_events().
>>
>> Could someone familiar with the code please have a look and  check  
>> the root cause of the problem.
>> I would be willing to work on a patch.
> 
> Hi Rudolf,
> 
> Yes, we've been hit by this too. We only discovered it yesterday, so 
> thank you for mentioning it!
> 
> The patch you suggest does appear to work. We've developed some test 
> scripts which fail with the current NSCA versions, but pass after 
> applying your recommended changes. 
> 
> Our story is 
> here: http://altinity.blogs.com/dotorg/2007/01/the_importance_.html
> 
> Ethan, please consider adding the test scripts into the NSCA 
> distribution. We'd be happy to help with maintaining it.
> 
> Ton
> 
> http://www.altinity.com
> T: +44 (0)870 787 9243
> F: +44 (0)845 280 1725
> Skype: tonvoon
> 

Thanks for reporting this Rudolf.  And thanks Ton for the test scripts - 
they work slick!  Now I guess I'll have to learn some Perl so I can 
understand them. :-)

I'll add the tests to CVS and make a 2.7.1 release shortly.


Ethan Galstad,
Nagios Developer
---
Email: nagios at nagios.org
Website: http://www.nagios.org

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