Adjust request headers when using proxy servers (former https.php)

proxy.php

<?php
/*
 * Detects a Request through HTTP/HTTPS Proxy and sets the coresponding server variables.
 *
 * usage:
 * in php.ini or .htaccess
 * php_value auto_prepend_file /var/www/proxy.php
 *
 * in pool.d for php-fpm
 * php_value[auto_prepend_file] = /var/www/proxy.php
 *
 */


//
// Detect SSL
//

if (array_key_exists('HTTP_SSL_ON', $_SERVER) && $_SERVER['HTTP_SSL_ON']) {
	$ssl = true;
} elseif (array_key_exists('HTTP_HTTP_SSL_ON', $_SERVER) && $_SERVER['HTTP_HTTP_SSL_ON']) {
	$ssl = true;
} elseif (array_key_exists('HTTPS', $_SERVER) && ($_SERVER['HTTPS'] === 'on') || ($_SERVER['HTTPS'] === 1)) {
	$ssl = true;
} elseif (array_key_exists('HTTP_X_FORWARDED_PROTO', $_SERVER) && $_SERVER['HTTP_X_FORWARDED_PROTO'] === 'https') {
	$ssl = true;
} else {
	$ssl = false;
}

unset($_SERVER['HTTP_SSL_ON']);
unset($_SERVER['HTTP_HTTP_SSL_ON']);
unset($_SERVER['HTTP_X_FORWARDED_PROTO']);

$_SERVER['HTTPS'] = $ssl ? 1 : 0;
$_SERVER['SERVER_PORT'] = $ssl ? '443' : $_SERVER['SERVER_PORT'];


//
// Detect Host
//

if (array_key_exists('HTTP_X_FORWARDED_HOST', $_SERVER)) {
	$host = $_SERVER['HTTP_X_FORWARDED_HOST'];
} else {
	$host = $_SERVER['HTTP_HOST'];
}

unset($_SERVER['HTTP_X_FORWARDED_HOST']);

$_SERVER['HTTP_HOST'] = $host;


//
// Detect Remote Addr
//

if (array_key_exists('HTTP_X_FORWARDED_FOR', $_SERVER)) {
	$remoteAddr = $_SERVER['HTTP_X_FORWARDED_FOR'];
} else {
	$remoteAddr = $_SERVER['REMOTE_ADDR'];
}

unset($_SERVER['HTTP_X_FORWARDED_FOR']);

$_SERVER['REMOTE_ADDR'] = $remoteAddr;

?>