How can I chab=nge the format of a URL?

Hi,

You can rewrite the URI using HTTP::uri or HTTP::path. You can retrieve the URI and path with these commands as well. You can use HTTP::query to get the query string value. You can use URI::query [HTTP::uri] param_name to get the value of a specific parameter in the query string.

Here is an untested example which should give you some ideas on how to do this. I made some assumptions about when you would want to rewrite the URI and which fields you would want to take from the original URI.

 
 when HTTP_REQUEST { 
  
    log local0. "[IP::client_addr]:[TCP::client_port]: New HTTP request to [HTTP::uri]" 
  
     Check the requested path? 
    if {[HTTP::path] eq "/adserver/impression/pid=123/oid=860/rand=12345/"}{ 
  
        Rewrite the URI to /ad.imp? then take the third through fifth fiels in the path 
          and append the query string parameter pclk with the value of click from the original query string 
       HTTP::uri "/ad.imp?[URI::path [HTTP::uri] 3 5]?pclk=[URI::query [HTTP::uri] click]" 
       log local0. "[IP::client_addr]:[TCP::client_port]: Rewrote URI to: /ad.imp?[URI::path [HTTP::uri] 3 5]?pclk=[URI::query [HTTP::uri] click]" 
    } 
 } 
 when HTTP_REQUEST priority 501 { 
  
     This event is just used for debug logging of the values that are cached in the default priority 500 HTTP_REQUEST event above 
       You can comment out or remove this event when you're done testing 
    log local0. "[IP::client_addr]:[TCP::client_port]: Actual updated URI: [HTTP::uri]" 
 } 
 

Aaron

How about this?

  
 when HTTP_REQUEST {   
    HTTP::uri [string map {"adserver/impression/pid=123/oid=860/rand=12345/?clic" "ad.imp?pid=123&oid=860&rand=12345/?pcl"} [HTTP::uri]]   
 }  
 

CB

Thanks, but the pid, oid and rand are variables. Is there a way to do it w/o knowing what those values are ahead of time?

Okay how about this

  
 when HTTP_REQUEST {  
   set uri [HTTP::uri]  
   scan $uri "adserver/impression/pid=%d/oid=%d/rand=%d" pidnum oidnum randnum  
   log local0. "This is the URI = $uri"  
   log local0. "Pid = $pidnum, Oid = $oidnum, rand = $randnum"  
   HTTP::uri [string map {"adserver/impression/pid=$pidnum/oid=$oidnum/rand=$randnum/?clic" "ad.imp?pid=$pidnum&oid=$oidnum&rand=$randnum/?pcl"} [HTTP::uri]]  
 }  
 

I have never done the string map with variables so I hope it works.

CB

Thanks for your help. Below is what I have, but it’s not quite working. If I implement the iRule, the page returns an error, which I expect because the web server doesn’t know what to with the new URL format yet, but the IIS logs don’t show the request making it that far. Do I have a syntax mistake somewhere?

 

 

when HTTP_REQUEST {

 

 

if { [HTTP::uri] contains "adserver/impression" }{

 

 

set uri [HTTP::uri]

 

 

scan $uri "adserver/impression/pid=%d/oid=%d/rand=%d" pidnum oidnum randnum

 

 

log local0. "This is the URI = $uri"

 

 

log local0. "Pid = $pidnum, Oid = $oidnumm, rand = $randnum"

 

 

 

HTTP::uri [string map {"adserver/impression/pid=$pidnum/oid=$oidnum/rand=$randnum/?click" "ad.imp?pid=$pidnum&oid=$oidnum&rand=$randnum/?pclk"} [HTTP::uri]]

 

 

}}

 

Yeah, that one burned me a long time ago and forgot about it. the "string map" command performs a literal replacement (ie. it doesn't do variable substitution). So in your example it was looking for the literal string "adserver/impression/pid=$pidnum/oid=$oidnum/rand=$randnum/?click" instead of the correct "adserver/impression/pid=123/oid=860/rand=12345/?click" Same goes for the replacement string.

Also, your second log statement as a typo with the $oidnumm variable which may throw an error.

The good news about the variable substitution is that you can fix that by wrapping the map strings with a "subst" command. This should work for you:

 when HTTP_REQUEST { 
   if { [HTTP::uri] contains "adserver/impression" }{ 
     set found [scan [HTTP::uri] "/adserver/impression/pid=%d/oid=%d/rand=%d" pidnum oidnum randnum] 
     if { $found == 3 } { 
       log local0. "This is the URI = [HTTP::uri]"  
       log local0. "Pid = $pidnum, Oid = $oidnum, rand = $randnum"  
       set newuri [string map [subst {"adserver/impression/pid=$pidnum/oid=$oidnum/rand=$randnum/?click" "ad.imp?pid=$pidnum&oid=$oidnum&rand=$randnum/?pclk"}] [HTTP::uri]]  
       log local0. "New URI: $newuri"; 
       HTTP::uri $newuri; 
     } 
   } 
 }

I threw in a sanity check for the scan to verify that it did indeed find the three values and I also put in the newly mapped URI into a variable and logged it so you can verify in the BIG-IP logs whether the "string map" worked. Oh, and I removed the $uri variable for optimization. You can remove the $newuri variable after you've tested and it works.

A fully optimized iRule would be this:

 when HTTP_REQUEST { 
   if { [HTTP::uri] contains "adserver/impression" }{ 
     set found [scan [HTTP::uri] "/adserver/impression/pid=%d/oid=%d/rand=%d" pidnum oidnum randnum] 
     if { $found == 3 } { 
       log local0. "This is the URI = [HTTP::uri]"  
       log local0. "Pid = $pidnum, Oid = $oidnum, rand = $randnum"  
       HTTP::uri [string map [subst {"adserver/impression/pid=$pidnum/oid=$oidnum/rand=$randnum/?click" "ad.imp?pid=$pidnum&oid=$oidnum&rand=$randnum/?pclk"}] [HTTP::uri]]  
     } 
   } 
 }

Hope this helps!

-Joe

If you replace the curly braces with double quotes, the variables can be expanded in string map:

 

 

% set find abc

 

abc

 

 

% set replace def

 

def

 

 

% string map {$find $replace} abcdefg

 

abcdefg

 

 

% string map "$find $replace" abcdefg

 

defdefg

 

 

Aaron

This looks right, but it is still passing the original URI. I'm stumped.

 

 

when HTTP_REQUEST {

 

 

if { [HTTP::uri] contains "adserver/impression" }{

 

 

set found [scan [HTTP::uri] "/adserver/impression/pid=%d/oid=%d/rand=%d" pidnum oidnum randnum]

 

 

if { $found == 3 } {

 

 

log local0. "This is the URI = [HTTP::uri]"

 

 

log local0. "Pid = $pidnum, Oid = $oidnum, rand = $randnum"

 

 

set newuri [string map [subst {"adserver/impression/pid=$pidnum/oid=$oidnum/rand=$randnum/?click" "ad.imp?pid=$pidnum&oid=$oidnum&rand=$randnum/?pclk"}] [HTTP::uri]]

 

 

log local0. "New URI: $newuri";

 

 

HTTP::uri $newuri;

 

 

}

 

 

}

 

 

}

THe URI is cached for the duration of the event, so if you move your log statement to a new HTTP_REQUEST event with a higher priority value you should see the correct value:

  
 when HTTP_REQUEST priority 501 {   
 log local0. "New URI: [HTTP::uri]"   
 }   
 

Oh, and remove those semi-colons.

updated above post...Monday brain fog.