CORS: Cannot use wildcard in Access-Control-Allow-

Question

I have a setup involving

Frontend server (Node.js, domain: localhost:3000) <---> Backend (Django, Ajax, domain: localhost:8000)

Browser <-- webapp <-- Node.js (Serve the app)

Browser (webapp) --> Ajax --> Django(Serve ajax POST requests)

Now, my problem here is with CORS setup which the webapp uses to make Ajax calls to the backend server. In chrome, I keep getting

Cannot use wildcard in Access-Control-Allow-Origin when credentials flag is true.

doesn't work on firefox either.

My Node.js setup is:

var allowCrossDomain = function(req, res, next) {
    res.header('Access-Control-Allow-Origin', 'http://localhost:8000/');
    res.header('Access-Control-Allow-Credentials', true);
    res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
    next();
};

And in Django I'm using this middleware along with this

The webapp makes requests as such:

$.ajax({
    type: "POST",
    url: 'http://localhost:8000/blah',
    data: {},
    xhrFields: {
        withCredentials: true
    },
    crossDomain: true,
    dataType: 'json',
    success: successHandler
});

So, the request headers that the webapp sends looks like:

Access-Control-Allow-Credentials: true
Access-Control-Allow-Headers: "Origin, X-Requested-With, Content-Type, Accept"
Access-Control-Allow-Methods: 'GET,PUT,POST,DELETE'
Content-Type: application/json 
Accept: */*
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Cookie: csrftoken=***; sessionid="***"

And here's the response header:

Access-Control-Allow-Headers: Content-Type,*
Access-Control-Allow-Credentials: true
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: POST,GET,OPTIONS,PUT,DELETE
Content-Type: application/json

Where am I going wrong?!

Edit 1: I've been using chrome --disable-web-security, but now want things to actually work.

Edit 2: Answer:

So, solution for me django-cors-headers config:

CORS_ORIGIN_ALLOW_ALL = False
CORS_ALLOW_CREDENTIALS = True
CORS_ORIGIN_WHITELIST = (
    'http://localhost:3000' # Here was the problem indeed and it has to be http://localhost:3000, not http://localhost:3000/
)

Answer 1

If you are using express you can use the cors package to allow CORS like so instead of writing your middleware;

var express = require('express')
, cors = require('cors')
, app = express();

app.use(cors());

app.get(function(req,res){ 
  res.send('hello');
});

Answer 2

try it:

const cors = require('cors')

const corsOptions = {
    origin: 'http://localhost:4200',
    credentials: true,

}
app.use(cors(corsOptions));

Answer 3

This is a part of security, you cannot do that. If you want to allow credentials then your Access-Control-Allow-Origin must not use *. You will have to specify the exact protocol + domain + port. For reference see these questions :

1. Access-Control-Allow-Origin wildcard subdomains, ports and protocols
2. Cross Origin Resource Sharing with Credentials

Besides * is too permissive and would defeat use of credentials. So set http://localhost:3000 or http://localhost:8000 as the allow origin header.

Answer 4

If you are using CORS middleware and you want to send withCredential boolean true, you can configure CORS like this:

var cors = require('cors');    
app.use(cors({credentials: true, origin: 'http://localhost:3000'}));

Answer 5

For development purposes in Chrome, installing this add on will get rid of that specific error:

Access to XMLHttpRequest at 'http://192.168.1.42:8080/sockjs-node/info?t=1546163388687' 
from origin 'http://localhost:8080' has been blocked by CORS policy: The value of the 
'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' 
when the request's credentials mode is 'include'. The credentials mode of requests 
initiated by the XMLHttpRequest is controlled by the withCredentials attribute.

After installing, make sure you add your url pattern to the Intercepted URLs by clicking on the AddOn's (CORS, green or red) icon and filling the appropriate textbox. An example URL pattern to add here that will work with http://localhost:8080 would be: *://*