rewrite a character with HTTP POST data

All you would need is an iRule that does inspection of the client data once a post is sent, and content replacement. You could use a string mapping or a regular expression, based on your needs. Have you searched the forums yet? There should be a few good examples either here or in the CodeShare.

 

 

Colin

A stream profile and rule to enable it should work nicely to rewrite the post data in requests. You'll want to try to be very specific on when you rewrite the & as this is typically used as a delimiter for post data parameters. You might want to use something like this:

  
  when HTTP_REQUEST {    
    
      Disable the stream filter by default    
     STREAM::disable    
    
      Check if the request is a POST, with a content type of text, from the Jakarta user agent  
     if {[HTTP::method eq "POST" && [HTTP::header value Content-Type] contains "text" \  
        && [HTTP::header value "User-Agent"] contains "Jakarta-HttpComponents"}{  
    
         Match the literal string "&" and replace it with and  
        STREAM::expression {@&@and@}   
    
         Enable the stream filter for this request only    
        STREAM::enable    
     }    
  }     
  when STREAM_MATCHED {  
      This event is only included for debugging.  You should remove the event after testing is complete.  
     log local0. "[IP::client_addr]:[TCP::local_port]: matched: [STREAM::match]"    
  }   
  

You could use a similar approach for rewriting the and back to & if it does appear in responses. Again, you'd want to try to be very specific about when you're rewriting the content as 'and' is a very common string.

Aaron

Actually, I would guess your app expects the & to be URL encoded if it shouldn't be interpreted as an &. I think you could replace the stream expression line in the example above, with:

 

 

STREAM::expression {@&@%26@}

 

 

I don't think you'd need to do any rewriting on responses if the application is standards compliant.

 

 

Aaron

Colin, I've checked the codeshare section and it suggested to use the http:collect and http:payload parameters. I tried building one from scratch but kept getting errors on the irule.

 

 

Aaron, all the requests are POST so I commented the" if" statement out. So for the expression, I should use

 

STREAM::expression {@&@%26@}

 

instead of

 

STREAM::expression {@&@and@}

 

 

I'm not sure what you mean by "URL encoded".

 

 

Also, when I look at the raw data, i see a "&" but I when export it and view in html, it shows just "&". Which one should I filter for?

 

 

thanks so much for the quick response!

 

 

Steve

Here is some info on URL (or percent) encoding:

http://en.wikipedia.org/wiki/Percent-encoding

Percent-encoding reserved characters

When a character from the reserved set (a "reserved character") has special meaning (a "reserved purpose") in a certain context, and a URI scheme says that it is necessary to use that character for some other purpose, then the character must be percent-encoded. Percent-encoding a reserved character involves converting the character to its corresponding value in ASCII and then representing that value as a pair of hexadecimal digits. The digits, preceded by a percent sign ("%"), are then used in the URI in place of the reserved character.

The reserved character "/", for example, if used in the "path" component of a URI, has the special meaning of being a delimiter between path segments. If, according to a given URI scheme, "/" needs to be in a path segment, then the three characters "%2F" or "%2f" must be used in the segment instead of a raw "/".

This blog entry (Click here) suggests you may need to XML encode the element value and then URL encode it. So the XML encoded equivalent for & is & amp ; (without the spaces). & amp ; (without the spaces) URL encoded would be %26amp;.

If you're able to test this, try the following rule which replaces & with %26amp;

    
      when HTTP_REQUEST {        
            
          Disable the stream filter by default        
         STREAM::disable        
            
          Check if the request is a POST, with a content type of text, from the Jakarta user agent      
         if {[HTTP::header value Content-Type] contains "text" \      
            && [HTTP::header value "User-Agent"] contains "Jakarta-HttpComponents"}{      
        
             Match the literal string "&" and replace it with %26amp;    
            STREAM::expression {@&@%26amp;@}    
        
             Enable the stream filter for this request only        
            STREAM::enable        
         }        
      }         
      when STREAM_MATCHED {      
          This event is only included for debugging.  You should remove the event after testing is complete.      
         log local0. "[IP::client_addr]:[TCP::local_port]: matched: [STREAM::match]"        
      }    
    

If that doesn't work, try replacing the STREAM::expression line with this:

STREAM::expression {@&@%26@}

Aaron