canonical URL Resolution for Asp.net Url-rewriting on IIS Server

Need small support for canonical URL. for all Asp.net website with URL re-writing there is two page keep coming when anyone search for a query string it will redirected to re-written URL, However in the case when URL is added with some additional conentet it can be created as duplicate URL. we need support for that, so that in any case whatever anyone done for an URL it must be open only one URL. we want to add Meta Tag canonical URL dynamically for all the pages with multiple products. Only Sample tip required.