tl;dr; How do I get Chrome to follow the 302 'Location' redirect to a different domain after an HTTP POST?
I'm using OpenID Connect, using an external provider to provide authentication services to my ASP.NET MVC (C#, .NET 6) application.
I have a controller action to close an account. In this instance,
[HttpPost("close-account")]
public async Task<IActionResult> CloseAccount()
{
// This does not work as expected in a POST and the browser does not redirect
var properties = new AuthenticationProperties { RedirectUri = "..." }
return SignOut(properties, "Cookies", "OpenIdConnect");
}
There is a standard html <form> which is completing the post action to the controller via a <button>. No Javascript involved.
Looking at the Chrome developer tools, the browser receives the 302 Found with the Location response header correctly set to the URL the browser needs to redirect to in order to complete the sign out with the OpenID Connect provider.
However, the browser does not follow the redirect. I am presuming because it is cross-origin, and starts with "https://oidc.myauthenticationprovider.com/logout?...." which is a different domain.
I have verified this - because if I change the redirect to be another URL in the same site, then the browser follows up with a GET to the URL provided in the Location header. It's just that if the origin is a different domain, it does nothing.
I only see this behaviour with POST. I have a similar GET endpoint to sign out users (without closing their account- just a regular sign-out) - which works perfectly.
[HttpGet("sign-out")]
public async Task<IActionResult> CloseAccount()
{
// This works as expected in a GET and the user is redirected.
var properties = new AuthenticationProperties { RedirectUri = "..." }
return SignOut(properties, "Cookies", "OpenIdConnect");
}
I'm not sure this is strictly a CORS issue because it is the response to an HTTP POST rather than an XHR request, however, I have tried the below in case it is related to CORS:
I have tried the services.AddCors method in the application startup, adding the origin
I have tried manually adding the Access-Control-Allow-Origin header to both the original GET and also the POST response of the close account page
These do not make a difference.
To the user, the behaviour is as if the form has done nothing. They press the button, and it seems like nothing at all happens. The code within the controller executes (in my example, the account does get closed), but the redirection is then ignored.
This was due to us setting the form-action: self directive in CSP. As described on MDN Web Docs,
Warning: Whether form-action should block redirects after a form
submission is debated and browser implementations of this aspect are
inconsistent (e.g. Firefox 57 doesn't block the redirects whereas
Chrome 63 does).
For us this was what was causing the blocked redirect to a different domain after form submission.
Mod note: This question is about why XMLHttpRequest/fetch/etc. on the browser are subject to the Same Access Policy restrictions (you get errors mentioning CORB or CORS) while Postman is not. This question is not about how to fix a "No 'Access-Control-Allow-Origin'..." error. It's about why they happen.
Please stop posting:
CORS configurations for every language/framework under the sun. Instead find your relevant language/framework's question.
3rd party services that allow a request to circumvent CORS
Command line options for turning off CORS for various browsers
I am trying to do authorization using JavaScript by connecting to the RESTful API built-in Flask. However, when I make the request, I get the following error:
XMLHttpRequest cannot load http://myApiUrl/login.
No 'Access-Control-Allow-Origin' header is present on the requested resource.
Origin 'null' is therefore not allowed access.
I know that the API or remote resource must set the header, but why did it work when I made the request via the Chrome extension Postman?
This is the request code:
$.ajax({
type: 'POST',
dataType: 'text',
url: api,
username: 'user',
password: 'pass',
crossDomain: true,
xhrFields: {
withCredentials: true,
},
})
.done(function (data) {
console.log('done');
})
.fail(function (xhr, textStatus, errorThrown) {
alert(xhr.responseText);
alert(textStatus);
});
If I understood it right you are doing an XMLHttpRequest to a different domain than your page is on. So the browser is blocking it as it usually allows a request in the same origin for security reasons. You need to do something different when you want to do a cross-domain request.
When you are using Postman they are not restricted by this policy. Quoted from Cross-Origin XMLHttpRequest:
Regular web pages can use the XMLHttpRequest object to send and receive data from remote servers, but they're limited by the same origin policy. Extensions aren't so limited. An extension can talk to remote servers outside of its origin, as long as it first requests cross-origin permissions.
WARNING: Using Access-Control-Allow-Origin: * can make your API/website vulnerable to cross-site request forgery (CSRF) attacks. Make certain you understand the risks before using this code.
It's very simple to solve if you are using PHP. Just add the following script in the beginning of your PHP page which handles the request:
<?php header('Access-Control-Allow-Origin: *'); ?>
If you are using Node-red you have to allow CORS in the node-red/settings.js file by un-commenting the following lines:
// The following property can be used to configure cross-origin resource sharing
// in the HTTP nodes.
// See https://github.com/troygoode/node-cors#configuration-options for
// details on its contents. The following is a basic permissive set of options:
httpNodeCors: {
origin: "*",
methods: "GET,PUT,POST,DELETE"
},
If you are using Flask same as the question; you have first to install flask-cors
pip install -U flask-cors
Then include the Flask cors package in your application.
from flask_cors import CORS
A simple application will look like:
from flask import Flask
from flask_cors import CORS
app = Flask(__name__)
CORS(app)
#app.route("/")
def helloWorld():
return "Hello, cross-origin-world!"
For more details, you can check the Flask documentation.
Because
$.ajax({type: "POST" - calls OPTIONS
$.post( - calls POST
Both are different. Postman calls "POST" properly, but when we call it, it will be "OPTIONS".
For C# web services - Web API
Please add the following code in your web.config file under the <system.webServer> tag. This will work:
<httpProtocol>
<customHeaders>
<add name="Access-Control-Allow-Origin" value="*" />
</customHeaders>
</httpProtocol>
Please make sure you are not doing any mistake in the Ajax call.
jQuery
$.ajax({
url: 'http://mysite.microsoft.sample.xyz.com/api/mycall',
headers: {
'Content-Type': 'application/x-www-form-urlencoded'
},
type: "POST", /* or type:"GET" or type:"PUT" */
dataType: "json",
data: {
},
success: function (result) {
console.log(result);
},
error: function () {
console.log("error");
}
});
Note: If you are looking for downloading content from a third-party website then this will not help you. You can try the following code, but not JavaScript.
System.Net.WebClient wc = new System.Net.WebClient();
string str = wc.DownloadString("http://mysite.microsoft.sample.xyz.com/api/mycall");
Deep
In the below investigation as API, I use http://example.com instead of http://myApiUrl/login from your question, because this first one working. I assume that your page is on http://my-site.local:8088.
NOTE: The API and your page have different domains!
The reason why you see different results is that Postman:
set header Host=example.com (your API)
NOT set header Origin
Postman actually not use your website url at all (you only type your API address into Postman) - he only send request to API, so he assume that website has same address as API (browser not assume this)
This is similar to browsers' way of sending requests when the site and API has the same domain (browsers also set the header item Referer=http://my-site.local:8088, however I don't see it in Postman). When Origin header is not set, usually servers allow such requests by default.
This is the standard way how Postman sends requests. But a browser sends requests differently when your site and API have different domains, and then CORS occurs and the browser automatically:
sets header Host=example.com (yours as API)
sets header Origin=http://my-site.local:8088 (your site)
(The header Referer has the same value as Origin). And now in Chrome's Console & Networks tab you will see:
When you have Host != Origin this is CORS, and when the server detects such a request, it usually blocks it by default.
Origin=null is set when you open HTML content from a local directory, and it sends a request. The same situation is when you send a request inside an <iframe>, like in the below snippet (but here the Host header is not set at all) - in general, everywhere the HTML specification says opaque origin, you can translate that to Origin=null. More information about this you can find here.
fetch('http://example.com/api', {method: 'POST'});
Look on chrome-console > network tab
If you do not use a simple CORS request, usually the browser automatically also sends an OPTIONS request before sending the main request - more information is here. The snippet below shows it:
fetch('http://example.com/api', {
method: 'POST',
headers: { 'Content-Type': 'application/json'}
});
Look in chrome-console -> network tab to 'api' request.
This is the OPTIONS request (the server does not allow sending a POST request)
You can change the configuration of your server to allow CORS requests.
Here is an example configuration which turns on CORS on nginx (nginx.conf file) - be very careful with setting always/"$http_origin" for nginx and "*" for Apache - this will unblock CORS from any domain (in production instead of stars use your concrete page adres which consume your api)
location ~ ^/index\.php(/|$) {
...
add_header 'Access-Control-Allow-Origin' "$http_origin" always;
add_header 'Access-Control-Allow-Credentials' 'true' always;
if ($request_method = OPTIONS) {
add_header 'Access-Control-Allow-Origin' "$http_origin"; # DO NOT remove THIS LINES (doubled with outside 'if' above)
add_header 'Access-Control-Allow-Credentials' 'true';
add_header 'Access-Control-Max-Age' 1728000; # cache preflight value for 20 days
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
add_header 'Access-Control-Allow-Headers' 'My-First-Header,My-Second-Header,Authorization,Content-Type,Accept,Origin';
add_header 'Content-Length' 0;
add_header 'Content-Type' 'text/plain charset=UTF-8';
return 204;
}
}
Here is an example configuration which turns on CORS on Apache (.htaccess file)
# ------------------------------------------------------------------------------
# | Cross-domain Ajax requests |
# ------------------------------------------------------------------------------
# Enable cross-origin Ajax requests.
# http://code.google.com/p/html5security/wiki/CrossOriginRequestSecurity
# http://enable-cors.org/
# <IfModule mod_headers.c>
# Header set Access-Control-Allow-Origin "*"
# </IfModule>
# Header set Header set Access-Control-Allow-Origin "*"
# Header always set Access-Control-Allow-Credentials "true"
Access-Control-Allow-Origin "http://your-page.com:80"
Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS, DELETE, PUT"
Header always set Access-Control-Allow-Headers "My-First-Header,My-Second-Header,Authorization, content-type, csrf-token"
Applying a CORS restriction is a security feature defined by a server and implemented by a browser.
The browser looks at the CORS policy of the server and respects it.
However, the Postman tool does not bother about the CORS policy of the server.
That is why the CORS error appears in the browser, but not in Postman.
The error you get is due to the CORS standard, which sets some restrictions on how JavaScript can perform ajax requests.
The CORS standard is a client-side standard, implemented in the browser. So it is the browser which prevent the call from completing and generates the error message - not the server.
Postman does not implement the CORS restrictions, which is why you don't see the same error when making the same call from Postman.
Why doesn't Postman implement CORS? CORS defines the restrictions relative to the origin (URL domain) of the page which initiates the request. But in Postman the requests doesn't originate from a page with an URL so CORS does not apply.
Solution & Issue Origins
You are making a XMLHttpRequest to different domains, example:
Domain one: some-domain.com
Domain Two: some-different-domain.com
This difference in domain names triggers CORS (Cross-Origin Resource Sharing) policy called SOP (Same-Origin Policy) that enforces the use of same domains (hence Origin) in Ajax, XMLHttpRequest and other HTTP requests.
Why did it work when I made the request via the Chrome extension
Postman?
A client (most Browsers and Development Tools) has a choice to enforce the Same-Origin Policy.
Most browsers enforce the policy of Same-Origin Policy to prevent issues related to CSRF (Cross-Site Request Forgery) attack.
Postman as a development tool chooses not to enforce SOP while some browsers enforce, this is why you can send requests via Postman that you cannot send with XMLHttpRequest via JS using the browser.
For browser testing purposes:
Windows - Run:
chrome.exe --user-data-dir="C://Chrome dev session" --disable-web-security
The command above will disable chrome web security. So for example if you work on a local project and encounter CORS policy issue when trying to make a request, you can skip this type of error with the above command. Basically it will open a new chrome session.
You might also get this error if your gateway timeout is too short and the resource you are accessing takes longer to process than the timeout. This may be the case for complex database queries etc. Thus, the above error code can be disguishing this problem. Just check if the error code is 504 instead of 404 as in Kamil's answer or something else. If it is 504, then increasing the gateway timeout might fix the problem.
In my case the CORS error could be removed by disabling the same origin policy (CORS) in the Internet Explorer browser, see How to disable same origin policy Internet Explorer. After doing this, it was a pure 504 error in the log.
To resolve this issue, write this line of code in your doGet() or doPost() function whichever you are using in backend
response.setHeader("Access-Control-Allow-Origin", "*");
Instead of "*" you can type in the website or API URL endpoint which is accessing the website else it will be public.
Your IP address is not whitelisted, so you are getting this error.
Ask the backend staff to whitelist your IP address for the service you are accessing.
Access-Control-Allow-Headers
For me I got this issue for different reason, the remote domain was added to origins the deployed app works perfectly except one end point I got this issue:
Origin https://mai-frontend.vercel.app is not allowed by Access-Control-Allow-Origin. Status code: 500
and
Fetch API cannot load https://sciigo.herokuapp.com/recommendations/recommendationsByUser/8f1bb29e-8ce6-4df2-b138-ffe53650dbab due to access control checks.
I discovered that my Heroku database table does not contains all the columns of my local table after updating Heroku database table everything worked well.
It works for me by applying this middleware in globally:
<?php
namespace App\Http\Middleware;
use Closure;
class Cors {
public function handle($request, Closure $next) {
return $next($request)
->header('Access-Control-Allow-Origin', '*')
->header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS')
->header('Access-Control-Allow-Headers', "Accept,authorization,Authorization, Content-Type");
}
}
I have a use-case where I need to spoof a white-listed Redirect URL locally when performing OAuth 2 authentication.
I'm running a very basic web-server coupled with a hosts file entry for the domain I'm spoofing. I'm able to correctly negotiate my tokens and return them to Paw, but Paw isn't picking up my access_token or refresh_token, it simply displays the raw response:
Here's my server code (with placeholders for sensitive data):
var http = require('http'),
request = require('request');
var PORT = 6109;
var server = http.createServer(function(req, res) {
var code = req.url.split('?')[1].split('=')[2];
request({
url: 'https://<access token URL>/oauth2/token?code=' + code,
method: 'POST',
form: {
'client_id': <client_id>,
'client_secret': <client_secret>,
'grant_type': 'authorization_code',
'redirect_uri': <spoofed redirect URL>
}
}, function(err, response, data) {
data = JSON.parse(data);
res.writeHead(200, {'Content-Type': 'application/json'});
res.write(JSON.stringify(data.result));
// I also tried this with the same end-result
// res.writeHead(200);
// res.write('access_token=' + data.result.access_token + '&token_type=' + data.result.token_type + '&refresh_token=' + data.result.refresh_token);
res.end();
});
});
server.listen(PORT, function() {
console.log('Server listening on port %d', PORT);
});
What am I missing? Why isn't Paw finding my tokens?
Here's my configuration for reference:
Some other noteworthy points:
The OAuth provider is non-standard and flubs quite a few things from the spec (my proxy exists in part to patch up the non-standard bits)
The domain for the Redirect URL is real, but the URL does not resolve (this is a part of the reason for the local hosts entry)
I'm not showing this part of the flow, but I am correctly completing the authorization step prior to being given the code value
I think you're probably confused between the Authorization URL and Access Token URL. When you're in Authorization Code grant type for OAuth 2, you're expected to have a user confirmation step in a web page (the Authorization URL).
Which makes me guess that instead, you're expecting instead to use the Password Grant or Client Credentials? Otherwise, if you want to use Authorization URL, you'll need to specify a webpage at the Authorization URL.
Note: I've tried your Node.js script in Paw using the two last grants I mentioned (Password Grant & Client Credentials), and it works nicely.
Update: Following the comments below, I understand more what you are doing. The Authorization Request should (if successful) return a 302 redirect response to the Redirect URL page, and append a code URL query param to it. It seems like you're returning a JSON response with the code instead, so Paw isn't catching it.
According to the OAuth 2.0 spec (RFC 6749), section *4.1.2. Authorization Response*, if granted, the code should be passed as a URL query param (i.e. a ?key=value param in the URL) to the Redirect URL when doing the redirection.
If the resource owner grants the access request, the authorization
server issues an authorization code and delivers it to the client by
adding the following parameters to the query component of the
redirection URI using the "application/x-www-form-urlencoded" format
Quoting the example from the spec, here's how the response of the Authorization Request should look like if it's a success (code is granted):
HTTP/1.1 302 Found
Location: https://client.example.com/cb?code=SplxlOBeZQQYbYS6WxSbIA
&state=xyz
I saw that the Redirect URL contains "my Spoofed Uri".
When we need to use authorization code flow, we provide the authorization code and redirect Uri.
When the URI you are providing does not match the URI saved for the client in Identity server, you will not be able to get the token as the URI does not match with the client authorization code.
For example : Consider client identity in the Identity server be:
Auth Code: "xyx"
Redirect Uri: "www.mylocalhost.com\xyz"
And in your example the combination you are providing is:
Auth Code: "xyx"
Redirect Uri: "<my spoofed uri>"
As these 2 wont match there will be no token received.
I believe if you use the correct URI that is registered with the client in the Identity server, you will be able to receive the token.
I have HTTPS server running on port 4443 and am using port forwarding to send 443 -> 4443 so in the browser you can't tell
In my OAuth settings when I use https://www.domain.com:4443/callback I get the response but in the popup it can't access the parent and I get this Chrome error
Blocked a frame with origin "https://www.domain.com:4443" from accessing a
frame with origin "https://www.domain.com". Protocols, domains, and ports must match.
When I change the url in the OAuth to 443 I get the beloved
`Invalid redirect_uri. This value must match a URL registered with the API Key.`
The only way I can think of is checking via javascript if the port is is the url, and if so to redirect to the url without the port.
Are there any more elegant solutions?
Since nobody has come up with an elegant solution, I thought I'd put my Javascript redirect answer.
What I did was, inside the window that accepts the redirect whose URL will look something like https://www.domain.com:4443/callback?aribtrary_data=1231252...etc... I wrap my callback code inside a try statement. If it fails, I redirect the current page to the same URL minus the port numbers.
Here's my Jade popup window solution which attempts to call the parent window upon finishing.
doctype html
html
head
title Authentication Popup
script.
var service = !{JSON.stringify(service)},
callback = 'on' + service.name + 'Auth';
window.onload = function () {
try {
window.opener[callback](service.error, service);
window.close();
} catch (e) {
window.location = window.location.href.replace(/(\.com)(:\d{3,4})?/, '$1');
}
}
body
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