Andres Olarte Andres Olarte - 3 months ago 16
Javascript Question

Detecting SNI (Server Name Indication) browser support in javascript

I want to be able to detect if the browser support SNI - Server Name Indication. I'm hoping to redirect non compliant clients to a different address.

I was thinking of loading some content through SSL and make sure it was transfered securely. Otherwise the browser doesn't support SNI. Can this be done?

Answer

You could set up a server that supports SNI, serving two host names, on where you require SNI and one that's a fallback solution, both serving the name that they are hosting.

Something along the lines of:

  • https://www.example.com/name returns a representation saying I'm www.example.com
  • https://www.example.net/name returns I'm www.example.net (and requires SNI).

If you make an XHR request to https://www.example.net/name and it returns www.example.com, then the browser doesn't support SNI.

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