ASP.net Associate session with client/request based on ip

In one web page we use a flash upload control but becouse a flash bug in the upload event the session is lost as its posted back with a new session.

We have tought of using a table with ip and old session id or a query string with the old session id in order to reassing it in the uploaded event...

Knowing the old session id how can i reass开发者_开发技巧ign it to the client? (In C#)

For tracking the user identity:

URL (a unique token in the query string)? i.e. redirect each visitor to same page with their own token in the URL.

Cookies?

For tracking the associated data:

Perhaps then store this user-specific data in an application-level store (keyed on the user token as above) such as Application object. Of course you should be concerned about the lifetime of this data and should consider persisting it to disk or to a database instead.

UPDATE

This (from the swfupload project) looks suspiciously like a work-around for the issue described here...

Or you could just use that tool instead of your current upload control?...

Does not work. The IP may hide many users - remember some people go throuh NAT devices sometimes involuntarily (their ISP enforces it, for example satellite providers), so you may have X users using the same IP.