Can iRule be used to modify HTML code itself being passed?

Of course you can modify the content in the response. You can use the HTTP::payload command to return the current payload into a variable, modify the content in that variable, and then issue the HTTP::payload command again passing in the new payload. To perform substitutions, you can use the TCL regsub or "string map" commands.

 

 

But, if you are doing a simple conversion from one string to another, the easiest approach is with the stream profile associated with your virtual server. This thread

 

 

http://devcentral.f5.com/Default.aspx?tabid=53&view=topic&forumid=5&postid=13504

 

Click here

 

 

 

goes over many options for replacing content in the response. The main thing to remember is that you need to have "Response Chunking" set to "Rechunk" in your HTTP profile if you are going to modify the length of the response payload.

 

 

-Joe

Thanks for pointing me to the Stream profile. I created a simple example and see it working.

 

 

I'm running 9.0 and 9.1. If I understand correctly, I can do a single string replacement in these versions, but if I wanted to do regex or multiple replacements, I need 9.2, correct?

I do believe that you'll need 9.2 to support multiple replacements in a single stream profile. Also the stream profile does not support regular expressions (as far as I know). For that route you'll have to do it manually with the HTTP::payload command in conjuction with the TCL regsub command.

 

 

-Joe

I was able to get regexes to work by wrapping the stream expression in {}'s:

This example looks for IP addresses in response content and replaces them with 0.0.0.0:

when HTTP_RESPONSE {
   STREAM::enable
   STREAM::expression {@\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}@0.0.0.0@}
}

Backreferences didn't seem to work though... the matched string is replaced with a literal \1.

Aaron