problem with findclass

Question

I have an iRule which uses the following statement    
   set myData [findclass [virtual] myClass]    
   where the class entries are as follows    
   class myClass {  
  "icmrdc2_80 field1 field2 field3"    
  "icmrdc2_8081 field1 field2 field3"  
  }    
   when the virtual name is icmrdc2_80, findclass always returns    
   "icmrdc2_8081 field1 field2 field3"However, if the class entries are as follows    
  class myClass {   
  "icmrdc_80 field1 field2 field3"    
  "icmrdc_8081 field1 field2 field3"  
  }    
  when the virtual name is icmrdc_80, findclass always returns the entry "icmrdc_80 field1 field2 field3"    
  How do I make the findclass always search for an exact match?

thanks,    
    Al

hoolio · Answer

Hello Al, 
  
 finclass does a hardcoded wildcard match of the string against each line of the datagroup.  I don't think there is a way around this.  Perhaps you could make a feature request through F5 Support to provide an option for glob or specific matching against just the first "field" of the datagroup.  In the meantime, you could use a for loop and getfield to perform an exact match against the class:

when RULE_INIT { 
  
     Create a test class (actually a list in this case).  This could also be defined as a class/datagroup. 
    set ::test_class [list {field1 value1} {field1* value1} {field2 value2} {field11 value11}] 
  
     Loop through the datagroup line by line. 
    foreach element $::test_class { 
  
        Log the current line. 
       log local0. "Current \$element: $element" 
  
        Compare the element against the string. 
        If the datagroup entry has a wildcard, it should be listed first in the string compare statement. 
       if {[string match -nocase [getfield $element " " 1] "field11"]}{ 
  
           Found a match, so log it and break out of the foreach loop. 
          log local0. "Matched \$element: $element.  Value: [getfield $element " " 2]. Exiting loop." 
          break 
       } 
    } 
 }

Log output:

Rule : Current $element: field1 value1 
 Rule : Current $element: field1* value1 
 Rule : Matched $element: field1* value1.  Value: value1. Exiting loop.

If you don't want wildcard matching, you can test with this version which doesn't have a wildcard in the datagroup:

when RULE_INIT { 
  
     Create a test class (actually a list in this case).  This could also be defined as a class/datagroup. 
    set ::test_class [list {field1 value1} {field2 value2} {field11 value11}] 
  
     Loop through the datagroup line by line. 
    foreach element $::test_class { 
  
        Log the current line. 
       log local0. "Current \$element: $element" 
  
        Compare the element against the string. 
        If the datagroup entry has a wildcard, it should be listed first in the string compare statement. 
       if {[string match -nocase [getfield $element " " 1] "field11"]}{ 
  
           Found a match, so log it and break out of the foreach loop. 
          log local0. "Matched \$element: $element.  Value: [getfield $element " " 2]. Exiting loop." 
          break 
       } 
    } 
 }

Rule : Current $element: field1 value1 
 Rule : Current $element: field2 value2 
 Rule : Current $element: field11 value11 
 Rule : Matched $element: field11 value11.  Value: value11. Exiting loop.

Aaron

al_carandang_11 · Answer

Got an answer from F5.  The value returned when there are multiple matches is arbitrary and depends on how the class gets loaded in memory. 
&nbsp;  
&nbsp; To solve the problem, the code should be written asset myData [findclass "[virtual] " myClass] 
&nbsp;  
&nbsp; -Al 
&nbsp;  
&nbsp;  &nbsp;

al_carandang_11 · Answer

Ran into some strange behaviour again.  If the statement isset Base [virtual]  
  set myData [findclass "$Base " myClass " "]  
  myData is always empty      
        
    -Al

al_carandang_11 · Answer

found the answer... I was specifying the " " separator in the last case wherease I wasn't specifying one in the first.

hoolio · Answer

Don't you need to refer to the class as ::class (or $::class in pre-9.4.2)? 
&nbsp;  
&nbsp; Aaron

Forum Discussion

problem with findclass

8 Replies

F5 Academy at AppWorld 2026

Introducing the F5 AI Assistant for BIG-IP

Recent Discussions

How can I get started with iCall

SSL Bridging and FQDN rewrite Policy

After upgrading from PeopleTools 8.59.11 to 8.61.11 F5 APM is not rewriting the internal URLs

Could not communicate with the system. Try to reload page.

F5 BIG IP laboratory license

Related Content

Troubleshooting TLS Problems With ssldump

Source_Addr Persistence Problems

C3D first request problem

F5 Access 3.1.0 for Android problem

Problem about Export imformation to Excel

ABOUT DEVCENTRAL

RESOURCES

SUPPORT

PARTNERS