2.0b3 hacks: checks.c - failure message from one plugin as output of (2) others ...

[Stanley Hopcroft]

Dear Folks,

I hoping for some enlightenment on what I may have done to checks.c to 
cause one plugins output to appear in the logs as the output of another 
(couple) of plugins.

[1113611613] EXTERNAL COMMAND: DISABLE_SVC_NOTIFICATIONS;external;ATMOSS 
search
[1113611627] EXTERNAL COMMAND: SCHEDULE_FORCED_SVC_CHECK;external;ATMOSS 
search;1113611624

 .. modified Perl plugin 'check_atmoss' to raise a syntax error (to 
    check that checks.c reports it and recovers when the error is 
    corrected)

[1113611638] SERVICE ALERT: external;ATMOSS search;UNKNOWN;SOFT;1;"**ePN 
failed to compile "/usr/local/nagios/libexec/check_atmoss": "syntax 
error at (eval 68) line 50, near "use Getopt::Long"" at 
/usr/local/nagios/bin/p1.pl line 255, <DATA> line 225.


  .. Ok so far.

[1113611638] SERVICE ALERT: foo-internet;Internet access to 
foo;UNKNOWN;SOFT;1;"**ePN failed to compile 
"/usr/local/nagios/libexec/check_atmoss": "syntax error at (eval 68) 
line 50, near "use Getopt::Long"" at /usr/local/nagios/bin/p1.pl line 
255, <DATA> line 225.

[1113611638] SERVICE ALERT: foo-prod;prod access to 
foo;UNKNOWN;SOFT;1;"**ePN failed to compile 
"/usr/local/nagios/libexec/check_atmoss": "syntax error at (eval 68) 
line 50, near "use Getopt::Long"" at /usr/local/nagios/bin/p1.pl line 
255, <DATA> line 225.

  .. Whoops ! foo-internet and foo-prod are both check_tcp ! The normal
     plugin output of check_tcp has been replaced by that from the
     Perl plugin check_atmoss.

[1113611698] SERVICE ALERT: foo-internet;Internet access to 
foo;OK;SOFT;2;TCP OK - 0 second response time on port 514
[1113611698] SERVICE ALERT: foo-prod;prod access to 
foo;OK;SOFT;2;TCP OK - 0 second response time on port 514

  .. Now back to normal.

[1113611818] SERVICE ALERT: external;ATMOSS search;UNKNOWN;SOFT;2;**ePN 
"/usr/local/nagios/libexec/check_atmoss": "syntax error at (eval 68) 
line 50, near "use Getopt::Long"".
[1113611998] SERVICE ALERT: external;ATMOSS search;UNKNOWN;HARD;3;**ePN 
"/usr/local/nagios/libexec/check_atmoss": "syntax error at (eval 68) 
line 50, near "use Getopt::Long"".
[1113612066] EXTERNAL COMMAND: SCHEDULE_FORCED_SVC_CHECK;external;ATMOSS 
search;1113612062
[1113612068] SERVICE ALERT: external;ATMOSS search;OK;HARD;3;ATMOSS 
Transaction completed Ok.


The context of these remarks is embedded Perl.

I have changed checks.c to return immediately after a failure of 
perl_call_argv(). In other words, when Perl reports that a plugin fails 
to compile, it sets ERRSV (to report the syntax error) and this causes 
checks.c to

 - fill out the remaining fields in struct svc_msg

 - write the struct to the IPC pipe

 - return 

This saves the futile running of a plugin with syntax errors in the 
grandchild process (and an equally futile extra call to Perl to run the 
plugin in perl_call_pv()). Currently, checks.c caches the error in 
memory and when the grandchild calls perl_call_pv() to run it, Perl 
inspects the cached error and either returns immediately or runs and 
returns the plugin output).

Obviously I fail to understand something here, so any clues are 
welcome.

Here is the hacked checks.c

                if ( SvTRUE(ERRSV) ) {
                                                        /*
                                                         * if 
SvTRUE(ERRSV)
                                                         *      write 
failure to IPC pipe
                                                         *      return
                                                         */

                        pclose_result=STATE_UNKNOWN;
                        perl_plugin_output=SvPVX(ERRSV);
#ifdef DEBUG1
                        printf("embedded perl ran %s with compile error 
%s - skipping plugin\n",fname,perl_plugin_output);
#endif

                        /* get the check finish time */
                        gettimeofday(&end_time,NULL);

                        /* record check result info */
                        
strncpy(svc_msg.output,perl_plugin_output,sizeof(svc_msg.output)-1);
                        svc_msg.output[sizeof(svc_msg.output)-1]='\x0';
                        svc_msg.return_code=pclose_result;
                        svc_msg.exited_ok=TRUE;
                        svc_msg.check_type=SERVICE_CHECK_ACTIVE;
                        svc_msg.finish_time=end_time;
                        svc_msg.early_timeout=FALSE;

                        /* write check results to message queue */
                        write_svc_message(&svc_msg);

                        return ;

                }
#endif

                                                        /*
                                                         * Plugin is a C 
plugin or a Perl plugin _without_ compilation errors
                                                         */

.. contine to run the plugin in grandchild process ..

Yours sincerely.


 -- 
Stanley Hopcroft

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