Question

Because header("Location: "); header needs to be used with absolute paths rather then relative ones, I made up this function to get a absolute path by using the $_SERVER variables.

function getAbsolutePath($relativePath = "/site/123/") {
if (isset($_SERVER['HTTPS'])) {
    $protocol = 'https'; 
} else {
    $protocol = 'http';
}

$host = $_SERVER['HTTP_HOST'];

$port = $_SERVER['SERVER_PORT'];

$absolutePath = 'Location: ' . $protocol . "://" . $host  . ":" . $port . $relativepath;
return $absolutePath;
}

Is this the perfect method to do so, or are they any better alternatives?

Answer 1

That’s the “textbook” way of making an absolute URI.

A few caveats I would like to highlight.

1. $_SERVER['HTTPS'] may not always be defined; the condition of $_SERVER['SERVER_PORT'] == 443 should be inspected in that case; if you’re behind a HTTPS load balancer that forwards the traffic via HTTP and none of the aforementioned methods work, you may have to hard code it.

2. $_SERVER['HTTP_HOST'] is not always defined either; this happens rarely, HTTP/0.9 didn’t define it and some home brew HTTP scripts may not pass it. You could look at $_SERVER['SERVER_NAME'] to find an alternative.

3. If the protocol and port is http, 80 or https, 443 respectively, you don’t need to add :$port.