You can't.

Okay, that's not true. If you have complete control of all client machines, such that all access went through your preferred mechanism, with no possible way anyone could ever access your program from any other mechanism, you can. (The statelessness of HTTP combined with the open access to any URI-accessible resource necessitates these strong steps.)

That's probably impractical -- so you can't.

In reply to Re: How to reliably get referrer? by chromatic
in thread How to reliably get referrer? by punch_card_don

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