Ajax CORS Request with http 401 in preflight

Question

I am struggling for hours now. I want to make a simple ajax request to another domain, but get http 401 Error all the time:

jQuery(document).ready(function($){
  var challengeid = $('#codepressHook').data('challengeid');
  var clicked = false;
  $('#codepressHook').click(function(){
    if(!clicked){
      $.ajax({
        url: "https://dev.radbonus.com/admin/affiliate-connections/retrieveSingle/"+challengeid+".json",
        method: "GET",
        dataType: "json",
        jsonp: false,
        contentType: "application/json",
        xhrFields: {
          withCredentials: true
        },
        beforeSend: function(xhr){
          xhr.setRequestHeader("Authorization", "Basic "+ btoa(username+":"+password));
        },
        success: function(data){
          $('#codepressHock').html(data.data.code);
        },
        error: function(error){
          alert(error);
        }
      });
    }
  });
});

I set all relevant CORS headers on the serverside. Here is the network traffic:

Request URL:https://dev.radbonus.com/admin/affiliate-connections/retrieveSingle/45.json
Request Method:OPTIONS
Status Code:401 Unauthorized
Remote Address:185.102.94.230:443
Referrer Policy:no-referrer-when-downgrade

Response Headers
view source
Access-Control-Allow-Credentials:true
Access-Control-Allow-Headers:Content-Type, X-Requested-With, Authorization, Origin
Access-Control-Allow-Methods:POST, GET, PUT, DELETE, OPTIONS
Access-Control-Allow-Origin:http://radbonus.com
Access-Control-Max-Age:31536000
Content-Length:463
Content-Type:text/html; charset=iso-8859-1
Date:Sat, 24 Jun 2017 11:25:33 GMT
Server:Apache/2.4.18 (Ubuntu)
WWW-Authenticate:Basic realm="Admin"

Request Headers
view source
Accept:*/*
Accept-Encoding:gzip, deflate, sdch, br
Accept-Language:de-DE,de;q=0.8,en-US;q=0.6,en;q=0.4
Access-Control-Request-Headers:authorization,content-type
Access-Control-Request-Method:GET
Connection:keep-alive
Host:dev.radbonus.com
Origin:http://radbonus.com
Referer:http://radbonus.com/plugintest/
User-Agent:Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36

I know that there are a lot of posts on this topic, but it seems I'm missing something simple. Could anyone help me?

Answer 1

UPDATE Looks like I was not right. Authorization header is never sent for OPTIONS request. Please see comment by sideshowbarker - you need to make sure that your server doesn't respond with 401 to OPTIONS request.

I don't know what language is your server written in, but you implemented authorization in the wrong way - OPTIONS method should be excluded from auth. Also see here - OPTIONS request authentication

Below is obsolete answer:

Your serverside requires HTTP Basic authentication for this request. And you don't provide credentials. 401 error has nothing to do with CORS; it just means that the server chose to not authorize your request because you didn't provide auth credentials.

If you try to open this url (like https://dev.radbonus.com/admin/affiliate-connections/retrieveSingle/1.json) directly in browser, you will be asked to enter login&password, which is how the browser handles 401 error with WWW-Authenticate header.

Please notice that Authorization header is actually not included with your request. So instead of using beforeSend hook, you should probably just include header directly in your call:

headers: {
    'Authorization': 'Basic ' + btoa(username+':'+password),
},

And make sure that Authorization header presents in your request.

Answer 2

Browsers make a Pre-flight request with method - OPTIONS, with the header names(only) you will be sending for actual request, before the actual GET/POST/PUT method. That is why your Pre-flight request headers looks like this,

**Access-Control-Request-Headers:authorization,content-type**

Now, in your Server, you should return HTTP_STATUS.OK - 200, for the OPTIONS request. If it returns any other status, then your actual request won't be made to server.

Here is a Good reading on CORS. https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS

I've faced this same issue recently and fixed by returning, 200 for the OPTIONS method in my Servlet Filter(SpringBoot).