304 Status responses bug discovered

Does the iRule work? If so, I think it looks okay. I don't fully understand the bug though. If the server sends a 304 it can't send cotent. So why do you want to rewrite the response to a 200? Wouldn't the client get a 200 with no data and assume the object did exist but has 0 length?

If you use that rule, you could streamline it slightly by removing the check if the IMS header does not exist:

 
 when HTTP_REQUEST { 
    if {[HTTP::header exists "If-Modified-Since"] } { 
       set ims 1 
       if { $::debug>=1 } { log local0. "Bingo found an If-Modified-Since from User" } 
    } else { 
       set ims 0  
    }  
 }  
 when HTTP_REQUEST_SEND {  
    TCP::collect 12  
 } 
 when SERVER_DATA {  
    if { [findstr [TCP::payload 12] "304"] == "304" and [info exists ims] and $ims ==0} {  
       TCP::payload replace 9 3 "200"  
    }  
 } 
 

Aaron