Forum Discussion

Log4j2's avatar
Log4j2
Icon for Altocumulus rankAltocumulus
Aug 02, 2021

Best way to limit what URI/Path is available

I currently have an iRule that will forward traffic to a destination pool based on what was in the host value:

when HTTP_REQUEST { 
 if { [string tolower [HTTP::host]] contains "example1.mydomain.com" } { 
pool /Common/App_Example_1.app/Pool_Example_1_pool
 } elseif { [string tolower [HTTP::host]] contains "example2.mydomain.com" } { 
pool /Common/App_Example_2.app/Pool_Example_2_pool
 } else { 
 pool /Common/App_Example_3.app/Pool_Example_3_pool
 }
}

For that second host (example2.mydomain.com) I want to make it so that only 3 URI's are actually available, let's say:

/v1/this/should/work*

/v1/this/will/also/work*

v2/this/one/too*

Everything else should be logged and blocked while presented a page about not being allowed

Here's what I tried:

when HTTP_REQUEST { 
 if { [string tolower [HTTP::host]] contains "example1.mydomain.com" } { 
pool /Common/App_Example_1.app/Pool_Example_1_pool
 } elseif { [string tolower [HTTP::host]] contains "example2.mydomain.com" } { 
  		 if { (([string tolower [HTTP::uri]] starts_with "/v1/this/should/work") or ([string tolower [HTTP::uri]] starts_with "/v1/this/will/also/work") or ([string tolower [HTTP::uri]] starts_with "v2/this/one/too")) } {
              pool /Common/App_Example_2.app/Pool_Example_2_pool
  		 } else {
  			log local0. "Blocked - [HTTP::host] - [HTTP::uri] from [IP::client_addr]"
  			HTTP::respond 200 content {
  				<html>
  				 <head>
  					<title>Access Denied</title>
  				 </head>
  				 <body>
  					You are not authorized to access the requested resource
  				 </body>
  				</html>
  			}
  		}
   } else { 
   pool /Common/App_Example_3.app/Pool_Example_3_pool
   }
  }

In this update it now just seems to block every request, regardless of the URI.

Is there a better way to do this outside of an iRule? What would make this iRule work? I also tried nesting "if" statements but that also didn't work.

Thanks!

BIG-IP
devops
iRules
  • spalande's avatar
    spalande
    Aug 03, 2021

    This can be optimized using switch statement. Create string datagroup (example2_allowed_uri) for allowed uri. You can use default_pool to send traffic at the end or reject it if there is no match for the HOST. 

    when HTTP_REQUEST {
    switch -glob [string tolower [HTTP::host]] {
        "example1.mydomain.com" 
       {
	     pool /Common/App_Example_1.app/Pool_Example_1_pool
	   } 
	   "example2.mydomain.com"
	   {
	     if { [class match [string tolower [HTTP::uri]] starts_with example2_allowed_uri ] } { 
		 pool /Common/App_Example_2.app/Pool_Example_2_pool
	     } else {
		   HTTP::respond 200 content "access denied" noserver Content-Type text/html Connection Close
		 }
	   }   
	   "example3.mydomain.com"
	   {
	     pool /Common/App_Example_3.app/Pool_Example_3_pool
	   }
	   default {
         pool default_pool
      }
    }
 }
  • spalande's avatar
    spalande
    Icon for Nacreous rankNacreous
    Aug 03, 2021

    This can be optimized using switch statement. Create string datagroup (example2_allowed_uri) for allowed uri. You can use default_pool to send traffic at the end or reject it if there is no match for the HOST. 

    when HTTP_REQUEST {
    switch -glob [string tolower [HTTP::host]] {
        "example1.mydomain.com" 
       {
	     pool /Common/App_Example_1.app/Pool_Example_1_pool
	   } 
	   "example2.mydomain.com"
	   {
	     if { [class match [string tolower [HTTP::uri]] starts_with example2_allowed_uri ] } { 
		 pool /Common/App_Example_2.app/Pool_Example_2_pool
	     } else {
		   HTTP::respond 200 content "access denied" noserver Content-Type text/html Connection Close
		 }
	   }   
	   "example3.mydomain.com"
	   {
	     pool /Common/App_Example_3.app/Pool_Example_3_pool
	   }
	   default {
         pool default_pool
      }
    }
 }
    • Log4j2's avatar
      Log4j2
      Icon for Altocumulus rankAltocumulus
      Aug 03, 2021

      Thank you ! This worked perfectly, I never thought to use DataGroups

       

      Thank you again, much appreciated!