Regarding Radon8472's code immediately below; since the response code always appears in the same place (just after the HTTP protocol and version), that's the only place where the response code needs to be looked for. And should be looked for: looking to see if it appears anywhere in any header is going to turn up all sorts of false positives.

Incidentally, 305 and 307 responses should also result in redirects.
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Server IP: 203.89.181.186
Probable Submitter: 114.134.161.9
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Manual Page -- http://www.php.net/manual/en/function.get-headers.php
Edit        -- https://master.php.net/note/edit/86152
Del: integrated  -- https://master.php.net/note/delete/86152/integrated
Del: useless     -- https://master.php.net/note/delete/86152/useless
Del: bad code    -- https://master.php.net/note/delete/86152/bad+code
Del: spam        -- https://master.php.net/note/delete/86152/spam
Del: non-english -- https://master.php.net/note/delete/86152/non-english
Del: in docs     -- https://master.php.net/note/delete/86152/in+docs
Del: other reasons-- https://master.php.net/note/delete/86152
Reject      -- https://master.php.net/note/reject/86152
Search      -- https://master.php.net/manage/user-notes.php