The ability to extract the original request URL has been included as part of struts 1.3 versions. All you've to do is - just fetch a request attribute.
Explanation: Struts team has introduced a new constant org.apache.struts.Globals.ORIGINAL_URI_KEY which holds the original URI of the request. Action servlet will set a request attribute with the above constant as the name and original URL as the value for this attribute.
The below statement will fetch original requested URL from client.