Deadly CORS when http://localhost is the origin

Question

I am stuck with this CORS problem, even though I set the server (nginx/node.js) with the appropriate headers.

I can see in Chrome Network pane -> Response Headers:

Answer 1

The real problem is that if we set -Allow- for all request (OPTIONS & POST), Chrome will cancel it. The following code works for me with POST to LocalHost with Chrome

<?php
if (isset($_SERVER['HTTP_ORIGIN'])) {
    //header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
    header("Access-Control-Allow-Origin: *");
    header('Access-Control-Allow-Credentials: true');    
    header("Access-Control-Allow-Methods: GET, POST, OPTIONS"); 
}   
if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {
    if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD']))
        header("Access-Control-Allow-Methods: GET, POST, OPTIONS");         
    if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']))
        header("Access-Control-Allow-Headers:{$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}");

    exit(0);
} 
?>

Answer 2

Chrome will make requests with CORS from a localhost origin just fine. This isn't a problem with Chrome.

The reason you can't load http://stackoverflow.com is that the Access-Control-Allow-Origin headers weren't allowing your localhost origin.

Answer 3

Chrome does not support localhost for CORS requests (a bug opened in 2010, marked WontFix in 2014).

To get around this you can use a domain like lvh.me (which points at 127.0.0.1 just like localhost) or start chrome with the --disable-web-security flag (assuming you're just testing).