How to force SNI only connections, or have a fallback non-SNI server?

[kriswpl]

I have the same problem to solve right now. And I see the good idea to
sort the type of SNI and non-SNI supported browsers.

But I made up that the user can connect to the server thru HTTP (no
SSL), and server determine what kind of browser it is (SNI or non) and
depending on the answer redirects to SSL on 443 (default https) for SNI
and 4433 for non-SNI.

So does anyone see how to determine if the client browser support SNI?

I am not talking about a bunch of ifs (browser.version < ... or
browser.version < ...).
I need more something like TLS+SNI support - yes|no - maybe this kind of
combination could tell us - ssl_protocols		SSLv3 TLSv1;

Thanks,
Chris

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,108417,220893#msg-220893