Changing HTTP Header Host port

Hi there,

You can strip out anything after the : in the host header using the getfield command (Click here) or using scan in an iRule:

  
  when HTTP_REQUEST {  
    
      Replace host header value with everything before the colon  
     HTTP::header replace Host "[getfield [HTTP::host] : 1]"  
    
     log local0. "[IP::client_addr]:[TCP::client_port]: Replace original host [HTTP::host] with [getfield [HTTP::host] : 1]"  
  }  
  

If the requests won't always have a port, you could check to see if the host header value contains a colon before replacing the value.

  
  when HTTP_REQUEST {  
    
      Check if host value has a colon  
     if {[HTTP::host] contains ":"}{  
    
         Replace host header value with everything before the colon  
        HTTP::header replace Host "[getfield [HTTP::host] : 1]"  
    
     log local0. "[IP::client_addr]:[TCP::client_port]: Replace original host [HTTP::host] with [getfield [HTTP::host] : 1]"  
     }  
  }  
  

Here is an example using scan (Click here😞

  
  when HTTP_REQUEST {  
    
      Scan the host header value. Save the results to $host and $port if there is a colon in the header value  
     if {[scan [HTTP::host] {%[a-zA-Z_.-]:%d} host port] == 2}{  
    
        HTTP::header replace Host $host  
     }  
  }  
  

I'm not sure whether scan would be more efficient than getfield. You could use the timing command to test this:

Timing command Click here, Timing article Click here

Aaron

Thanks Aaron - great info as ever!

 

 

I used the first example, and the Host header is being forwarded correctly without the port, so all good there. However, the Request URI needs to have the port stripped out too. How would I do this as well?

 

 

Thanks again.

 

 

Is the app including the port number in redirects? If so, you can try rewriting the redirects using the HTTP profile option. Or you can use an iRule:

 
 when HTTP_RESPONSE { 
  
     Check if response is a redirect 
    if {[HTTP::is_redirect]}{ 
  
        Replace :55555/ with / in the Location header 
       HTTP::header replace Location [string map {:55555/ /} [HTTP::header value Location]] 
    } 
 } 
 

If the port isn't in the Location header, can you explain where you're seeing it?

Aaron

Here's a version that is working for us (changing the Request Host header and URI), but hoping there's an easier way to modify the URI?

 

 

when HTTP_REQUEST {

 

Check if host value has a colon

 

if {[HTTP::host] contains ":"}{

 

log local0. "URI: [HTTP::uri]"

 

 

set find ":55555"

 

set replace ""

 

set uri_old [HTTP::uri]

 

regsub -all $find $uri_old $replace new_uri

 

HTTP::uri $new_uri

 

 

log local0. "NEW URI: [HTTP::uri]"

 

Replace host header value with everything before the colon

 

set new_host [getfield [HTTP::host] ":" 1]

 

 

HTTP::header replace "Host" $new_host

 

log local0. "[IP::client_addr]:[TCP::client_port]: Replace original host [HTTP::host] with [getfield [HTTP::host] ":" 1]"

 

}

 

}

 

 

Also, as you suggest, it looks like we'll need to modify the HTTP_Response Location header + any other references to objects in the HTTP_Response payload. May need to look at this...

 

http://devcentral.f5.com/weblogs/Joe/archive/2005/07/27/1398.aspx

 

 

Cheers.

Can you post some anonymized samples of the URI's you want to rewrite? Is the client using an absolute URI? Something like this?

 

 

GET http://www.w3.org:55555/pub/WWW/TheProject.html HTTP/1.1

 

User-Agent: ...

 

 

If so, you could use string map instead of regsub. The string function would be more efficient than a regex.

 

 

HTTP::uri [string map {:55555/ /} [HTTP::uri]]

 

 

If you also need to rewrite the port in response content, you could use a stream filter and STREAM::expression based iRule. This would be more efficient than collecting the response content and performing regex operations on it. You can check the STREAM::expression wiki page (Click here) for examples.

 

 

Aaron