proxy.php

<?php

$url = "http://" . substr($_SERVER["REQUEST_URI"], strlen("/proxy.php/"));

//fetch
$content = file_get_contents(
  $url,
  false,
  stream_context_create(array(
    'http' => array(
      'header' =>
        "User-agent: osmcz-https-proxy (Please enable https on your site, so we can offer your osm project directly. Thanks openstreetmap.cz)\r\n"
    )
  ))
);

foreach ($http_response_header as $r) {
  if (!preg_match("~^(HTTP/1|Date|Server)~", $r)) {
    header($r);
  }
}
header('Server: openstreetmap.cz-proxy');

echo $content;