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Richard_Jones's avatar
Richard_Jones
Icon for Nimbostratus rankNimbostratus
Jun 22, 2011

Different results from TCL regexp and iRules regexp

I am working on an iRule that will validate the value of a parameter only contains a-z, 0-9, and / + =. I have created a regexp pattern that works in TCL, but not in an iRule:

 

 

TCL:

 

 

% regexp {^(?:[a-z0-9/+=]+)$} 1324

 

1

 

% regexp {^(?:[a-z0-9/+=]+)$} asdf

 

1

 

% regexp {^(?:[a-z0-9/+=]+)$} wqer!

 

0

 

% regexp {^(?:[a-z0-9/+=]+)$} asfd/

 

1

 

 

iRule:

 

 

log local0. "Val: $decoded_val"

 

set res [regexp {^(?:[a-z0-9/+=]+)$} $val]

 

log local0. "Res: $res"

 

 

Output:

 

 

Rule validate_param : Val: 1324

 

Rule validate_param : Res: 0

 

Rule validate_param : Val: asdf

 

Rule validate_param : Res: 0

 

Rule validate_param : Val: wqer!

 

Rule validate_param : Res: 0

 

Rule validate_param : Val: asfd/

 

Rule validate_param : Res: 0

 

 

The same regexp pattern matches the correct 3 entries when run via tclsh, but doesn't match anything correctly when run through an iRule. Ideas??

 

 

I realize that regexp isn't the most efficient, so I'm open to other alternatives as well.

 

 

Thanks

 

 

Richard

 

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  • JRahm's avatar
    JRahm
    Icon for Admin rankAdmin
    Jun 22, 2011
    I'm not seeing the issue: 

    
when RULE_INIT {
foreach x [list "1234" "asdf" "wqer!" "asfd/"] {
log local0. "Val: $x"
set res [regexp {^(?:[a-z0-9/+=]+)$} $x]
log local0. "Res: $res"
}
}

Jun 21 22:57:12 local/tmm info tmm[5091]: Rule regexp_test : Val: 1234
Jun 21 22:57:12 local/tmm info tmm[5091]: Rule regexp_test : Res: 1
Jun 21 22:57:12 local/tmm info tmm[5091]: Rule regexp_test : Val: asdf
Jun 21 22:57:12 local/tmm info tmm[5091]: Rule regexp_test : Res: 1
Jun 21 22:57:12 local/tmm info tmm[5091]: Rule regexp_test : Val: wqer!
Jun 21 22:57:12 local/tmm info tmm[5091]: Rule regexp_test : Res: 0
Jun 21 22:57:12 local/tmm info tmm[5091]: Rule regexp_test : Val: asfd/
Jun 21 22:57:12 local/tmm info tmm[5091]: Rule regexp_test : Res: 1

    Perhaps the variable in the regexp should be $decoded_val?
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Jun 22, 2011
    You could also simplify the regex slightly by removing the parens as you're not using the capture group anyhow.

     

     

    set res [regexp {^[a-z0-9/+=]+$} $x]

     

     

    Aaron
  • Richard_Jones's avatar
    Richard_Jones
    Icon for Nimbostratus rankNimbostratus
    Jun 22, 2011
    hoolio, I made your change. Thanks. My regex-fu is weak these days....

     

     

    Jason, thanks for the quick demo, which I duplicated with my iRule and verified with plain text.

     

     

    The parameter value I'm inspecting is actually base64 encoded. I extract the value, base64 decode it, then run it through the regex. My log statement shows that I am correctly decoding the value. Just now, I added additional text to the end of a log statement and see that my base64 decoded string is actually "asdf ". I hadn't noticed that space last night....

     

     

    Now I just need to strip that space, and I should be good to go.

     

     

    Thanks for the help!

     

     

    R

     

  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Jun 23, 2011
    Now that you've figured out the regex option you could try using scan as well. scan is typically more efficient than a regex. 

       if {[scan $str {%[a-z0-9/+=]} match] and $match eq $str}{
      log local0. "matched $str"
   } else {
      log local0. "no match for $str"
   }


    foreach str [list "1234" "asdf" "wqer!" "asfd/"] {
   if {[scan $str {%[a-z0-9/+=]} match] and $match eq $str}{
      log local0. "matched $str"
   } else {
      log local0. "no match for $str"
   }
}

    matched 1234

    matched asdf

    no match for wqer!

    matched asfd/

    Aaron