I have react app what I already deployed to the GitHub Pages.
But now I have a problem: what I am requesting auth status to server and didn`t get any response. What is the problem?
I have this error in console about my requests
has been blocked by CORS policy:
Response to preflight request doesn't pass access control check:
No 'Access-Control-Allow-Origin' header is present on the requested resource
GitHub pages supports CORS since 2015, so you can follow "Fix CORS Error| React Tutorial" which points to:
"Run Chrome browser without CORS" (not recommended, just for testing)
axios/axios issue 853
That last issue mentions:
cURL does not enforce CORS rules. Those rules are enforced by browsers for security purposes.
When you mention that you added the relevant header, I assume you mean you added those headers to the request.
Actually, the header is expected in the response headers from the server, indicating that the resource is allowed to be accessed by other websites directly.
FYI, CORS - Cross Origin Resource Sharing. Since your API does not support it, you have two options -
Use a proxy server on the same domain as your webpage to access 4chan's API or,
Use a proxy server on any other domain, but modify the response to include the necessary headers.
Related
I was able to render Text contents from Magnolia public REST API on Salesforce community.
ISSUE: Image files are being blocked by CSP (Content Security Policy)
TRIED: Added the Base URL a few different ways to in Site URL in CSP Trusted Sites
https://*.magnolia-cms.com
https://*.demopublic.magnolia-cms.com
https://demopublic.magnolia-cms.com
Also, included https://demopublic.magnolia-cms.com url in Trusted Sites for Script
What I am missing here?
That looks like a typical case of forgetting setting the CORS headers on Magnolia site, hence browser blocking the request as required by the spec:
For security reasons, browsers restrict cross-origin HTTP requests initiated from scripts. For example, XMLHttpRequest and the Fetch API follow the same-origin policy. This means that a web application using those APIs can only request resources from the same origin the application was loaded from unless the response from other origins includes the right CORS headers.
More details here
If you haven't done so before, you can add simple static CORS definition in headers using AddHeadersFilter. It was discussed previously eg here
I'm a n00b trying to learn React. I'm building a website that uses Etsy's APIs. Registered an app there and everything. They have a page that talks about CORS and proxying here: https://www.etsy.com/developers/documentation/getting_started/jsonp
So for example, I'm trying to do a fetch on a store's listings:
fetch('https://openapi.etsy.com/v2/shops/[shopId]/listings/active?api_key=[apiKey]')
But that violates the browser's CORS policy. No problem, says the documentation on Etsy. You can always use their proxy: beta-api.etsy.com. So I add that to my package.json file:
"proxy": "https://beta-api.etsy.com/"
And then I change my fetch line:
fetch('/v2/shops/[shopId]/listings/active?api_key=[apiKey]')
But CORS is still being violated in the browser.
Access to fetch at 'https://www.etsy.com/shop/beta-api/v2/shops/[shopId]/listings/active?api_key=[apiKey]' (redirected from 'http://localhost:3000/v2/shops/[shopId]/listings/active?api_key=[apiKey]') from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
I don't want an opaque response, either, so doing "no-cors" really doesn't help. Does anyone have any recommendations on how I can at least get a local website up and running?
You are getting that error because your server has set Access-Control-Allow-Origin to restrict cross-domain traffic. You are sending your request from your localhost so that is considered cross-domain.
If you are able to change your server settings to set Access-Control-Allow-Origin: * then you can make those requests without a CORS error but I don't suggest doing this.
The best solution would probably be a proxy server. You can use cors-anywhere heroku app to easily do this.
Excerpt from Medium Article on this issue
The cors-anywhere server is a proxy that adds CORS headers to a
request. A proxy acts as an intermediary between a client and server.
In this case, the cors-anywhere proxy server operates in between the
frontend web app making the request, and the server that responds with
data.
Similar to the Allow-control-allow-origin plugin, it adds the
more open Access-Control-Allow-Origin: * header to the response.
Say your frontend is trying to make a GET request to:
https://joke-api-strict-cors.appspot.com/jokes/random
But this api does not have a Access-Control-Allow-Origin value
in place that permits the web application domain to access it.
So instead, send your GET request to:
https://cors-anywhere.herokuapp.com/https://joke-api-strict-cors.appspot.com/jokes/random
The proxy server receives the
https://joke-api-strict-cors.appspot.com/jokes/random
from the url above. Then it makes the request to get that server’s
response. And finally, the proxy applies the Access-Control-Allow-
Origin: * to that original response.
I succesfully installed "JWT Authentication for WP REST API" and followed (and reviewed multiple times) the instructions for setup correctly.
My React app does authenticate via the /jwt-auth/v1/token-endpoint.
I get a token back and store this in my localStorage.
All of my API-calls get added an authorization header as follows from this point on:
Authorization: Bearer mYCust0mToken
In the browser, this triggers preflight requests to the server (which is a remote one), that all fail. Basically logging in kills all of my API-requests.
I'm now getting 405's stating the following:
Access to fetch at
'https://mywebpage.com/wp-json/wp/v2/posts/'
from origin 'http://localhost:3000' has been blocked by CORS policy:
Response to preflight request doesn't pass access control check: No
'Access-Control-Allow-Origin' header is present on the requested
resource. If an opaque response serves your needs, set the request's
mode to 'no-cors' to fetch the resource with CORS disabled.
I run WP inside a subdir, so I have two .htaccess files, one in the root, one in the wp/-directory. I've tried putting the suggested .htaccess-changes of the descriptions in both files, on several positions of the file, but still no luck.
I've also tried setting Allow-Origin headers to "*", just for the sake of testing. I did that in both the .htaccess-files, but also in my PHP.
Anyone out there that got "JWT Authentication for WP REST API" up and running and willing to tell how?
when trying to $.ajax to fetch some content from other websites in my website, I got the error.
Failed to load https://www.pinterest.com/: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8100' is therefore not allowed access.
I knew if the target website didn't allow localhost:8100 to fetch the data, I cannot fetch it in the client side on the web.
However, I found that mobile app (not mobile browser, but android/ios application) does not have the issue, they can simply get the website content by their default mobile built-in HTTP get function.
Do i want to ask why mobile will not encounter CORS issue (mobile can fetch the webcontent simply by the built-in http get function)?
thanks.
CORS is enforced by the browser to fulfill the security standard they have to meet. It does not affect requests made programmatically from any language, like a curl call on bash.
This is how CORS works, based on Wikipedia:
The browser sends the OPTIONS request with an Origin HTTP header. The value of this header is the domain that served the parent page. When a page from http://www.example.com attempts to access a user's data in service.example.com, the following request header would be sent to service.example.com: Origin: http://www.example.com.
The server at service.example.com may respond with:
An Access-Control-Allow-Origin (ACAO) header in its response indicating which origin sites are allowed. For example Access-Control-Allow-Origin: http://www.example.com
An error page if the server does not allow the cross-origin request
An Access-Control-Allow-Origin (ACAO) header with a wildcard that allows all domains: Access-Control-Allow-Origin: *
The way CORS works means it is optional. Browsers enforce it to prevent Javascript AJAX calls to perform malicious calls. But other types of consumers built by hand don't need to enforce CORS.
Think in this example:
You are the owner of somesite.com
Users authenticate to your site using the traditional cookie method
User logins into anothersite.com, built by an attacker. This site has the following code:
<script>fetch('http://somesite.com/posts/1', { method: 'DELETE' });</script>
... effectively performing a request to your site and doing bad things.
Happily, the browser will perform a preflight request when it sees a cross-domain request, and if your site does not respond saying that requests coming from anothersite.com are OK, you will be covered by default from a potential attack
This is why CORS only makes sense in the context of a browser. Javascript you send to the browser can not (at least easily) circumvent CORS because the only API that allows you to perform requests from the browser is written in stone. Additionally, there are no local storage or cookies outside of the browser.
Corolarium: Enforcing CORS is a deliberate action from the requester, or whoever is making the requests for you, not the sender. Javascript APIs in browsers enforce it. Other languages don't have the need for the reasons explained.
When running on a device, your files are served over the file:// protocol, not http://, and your origin will therefore not exist. That's why the request from the native device does not trigger CORS.
I'm trying to fetch the list of official images from docker hub using v2 api. If I try to do curl or use postman, I get the response correctly, but when I try to fetch the list using angularjs service, I get the following error
XMLHttpRequest cannot load https://hub.docker.com/v2/repositories/library/?page=8&page_size=15. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://run.plnkr.co' is therefore not allowed access.
Can someone suggest solution for this. How can I enable cors for this?
CORS could be enabled on the server side, and this is not your case. What you could do is :
1) use a proxy, for instance NGNIX, and make Sure that all request Made to localhost/whatever are redirected to hub.docker.com . This way you can "cheat" Cross-origin block
2) if you need a temporary and dirty solution you could more simply install chrome/safari plugins to bypass CORS security check
There is only one way to bypass CORS is send request through a cors proxy like http://crossorigin.me
It's an opensource project and you can build your own proxy server by download the full source code from here: https://github.com/technoboy10/crossorigin.me
Reason behind the issue :
As per my understanding you are doing an AJAX call to a different domain than your page is on. So, the browser is blocking it for security reasons as it usually allows a request in the same origin.A tutorial about how to achieve that is using CORS.
When you are using curl or 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.