Attempting to insert HOST to HTTP::header fails

HTTP::host returns the value of the Host header. There's no value, so there's nothing to insert in your rule above.

 

There's a bit more on HTTP::host here, including a couple of examples:

 

http://devcentral.f5.com/wiki/default.aspx/iRules/HTTP__host.html

 

RFC2616 (covering HTTP/1.1) says that if no host is given in the URI (as in your example output above), the Host header should be blank:

 

  
 A client MUST include a Host header field in all HTTP/1.1 request  
 messages . If the requested URI does not include an Internet host  
 name for the service being requested, then the Host header field MUST  
 be given with an empty value. An HTTP/1.1 proxy MUST ensure that any  
 request message it forwards does contain an appropriate Host header  
 field that identifies the service being requested by the proxy. All  
 Internet-based HTTP/1.1 servers MUST respond with a 400 (Bad Request)  
 status code to any HTTP/1.1 request message which lacks a Host header  
 field.  
 

 

So what you've got there is actually a legal request, even if it's not what you're looking for (which may be only a small comfort).

 

 

If you need to strip the host out of an absolute URL (see HTTP::uri) , you can probably do it and then stuff that into a Host header.