iRule for taking part of an original URI and inserting to a new URL

Hi Bruce,

You can parse the value for a URI parameter using a slight change to URI::query:

URI::query "?&[HTTP::query] &param_name

So to parse the value of the Ntt parameter and use it in a URI rewrite, you can do something like this:

when HTTP_REQUEST {
    Check if some condition is true?
   if { [string tolower [HTTP::host]] eq "search.environment.domain" and [HTTP::path] eq "/listing" and [HTTP::query] contains "Ntt"}{
       Rewrite the URI with the original path and the query string replaced 
         with just the Ntt parameter value set for the q parameter
      HTTP::uri "/globalSearch?q=[URI::query "?&[HTTP::query] &Ntt]"
       Update the host header
      HTTP::header replace Host "www.environment.domain"
   }
}

Aaron

Hi Aaron,

Thanks for the above, but it looks like the URI is not being rewritten. The rule is being matched and the host header is changed, but the URI remains the same as original.

This is the request: (which the output URI should change to

Your modified iRule is below with the logging statements in I am using.

 
when HTTP_REQUEST { 
 Check if some condition is true? 
if { [string tolower [HTTP::host]] eq "search.devint.lpo" and [HTTP::path] eq "/listing" and [HTTP::query] contains "Ntt"} 
{  Log the original Host and URI request 
log local0. "Original Client Request is: [HTTP::header value host][HTTP::uri]" 
 Rewrite the URI with the original path and the query string replaced 
 with just the Ntt parameter value set for the q parameter 
HTTP::uri "/globalSearch?q=[URI::query "?&[HTTP::query] &Ntt"]" 
 Update the host header 
HTTP::header replace Host "www.devint.lpo" 
 Log the modified Host and URI 
log local0. "Modified Client Request is: [HTTP::header value Host][HTTP::uri]" 
}
 }

LTM Log output:

tmm tmm[1817]: Rule searchrewrite.iRule.devint : Original Client Request is: search.devint.lpo/listing?Ntt=test

tmm tmm[1817]: Rule searchrewrite.iRule.devint : Modified Client Request is: www.devint.lpo/listing?Ntt=test

Any thoughts?

Thanks,

Bruce

FYI- It's BIG-IP Version 9.4.7 320.1

Hi Bruce,

The values for most HTTP:: commands are cached in the same event of the same priority. To log the updated value, you can add a second HTTP_REQUEST event which runs after the default priority of 500:

when HTTP_REQUEST { 
    Check if some condition is true? 
   if { [string tolower [HTTP::host]] eq "search.devint.lpo" and [HTTP::path] eq "/listing" and [HTTP::query] contains "Ntt"} {
       Log the original Host and URI request 
      log local0. "Original Client Request is: [HTTP::header value host][HTTP::uri]" 

       Rewrite the URI with the original path and the query string replaced 
       with just the Ntt parameter value set for the q parameter 
      HTTP::uri "/globalSearch?q=[URI::query "?&[HTTP::query] &Ntt"]" 

       Update the host header 
      HTTP::header replace Host "www.devint.lpo" 

   }
}
when HTTP_REQUEST priority 501 {
    Log the modified Host and URI 
   log local0. "(501) Modified Client Request is: [HTTP::header value Host][HTTP::uri]" 
}

Aaron

Aaron,

Wrong Host? You want to change the URL host and not the Host header.

when HTTP_REQUEST { 
 if it matches the request replace the request with a new one passing the old parameter.
  if { "[HTTP::host]/[HTTP::path]?[HTTP::query]" starts_with "search.devint.lpo/listing?Ntt=" } {
    HTTP::host "www.devint.lpo"
    HTTP::uri [concat "/globalSearch?q=" [URI::query "?[HTTP::query]" "Ntt"]]
  }
}
when HTTP_REQUEST priority 501 {
...as above...
}

Syntax of the 5th line needs to be verified. Ill test it shortly and report back if there is any issues.

Regards

Kevin

Hi Kevin,

 

 

The forum software double HTML encodes &'s in code blocks and so they were displaying as & amp ; (without the spaces). I've edited that now. Can you retry the updated version above?

 

 

Aaron

Hi Aaron and Kevin,

 

 

All sorted now, thanks for your help.

 

 

Bruce

Hi Kev,

 

 

By default most HTTP user agents don't use fully qualified URLs in the URI field. So you can just replace the HTTP host header using 'HTTP::header replace Host "newhost.example.com". If a user agent did include the host in a fully qualified URL in the URI, the server must ignore the host header. In that case, you'd want to replace the host portion in the URI. However, the only times I've seen clients doing this is when they're using a web proxy. Most web proxies convert the URI to a local reference when sending the requests on.

 

 

Also, HTTP::host only allows you to retrieve the host header value--not set it.

 

 

Aaron