#ACCESS CONTROL ALLOW ORIGIN PHP CODE#

Typically, Access-Control-Allow-Origin responses are passed on to the requesting origin without credentials such as cookies or authorization headers, even if these are sent with the request. Passing credentials with cross-origin resource requests

The browser compares the allowed origin in the header to the requesting Origin A and shares the response if these match.

The Origin B server responds and includes Access-Control-Allow-Origin: in the header.

Origin A ( ) requests access to resources from Origin B ( ) through, for example, a request header and GET method.

Roughly speaking, this would look like this: The browser will not share the server response if the origin is not included in the header.

#ACCESS CONTROL ALLOW ORIGIN PHP CODE#

If they do, it proceeds with the request and allows code running on the requesting website to access the response. The client (browser) then compares the origin of the website requesting access to the one specified in the header response by the domain serving the resource to determine if they match. In addition, it will specify which request origin is allowed. When the Access-Control-Allow-Origin response header is implemented, it will be included in the response of one server (domain) to another that is making the cross-origin request. You can learn more about the different types of headers utilized as a part of CORS from Mozilla’s detailed Cross-Origin Resource Sharing (CORS) article.

Under CORS, many additional headers are used both in the cross-origin request and response to navigate the exchange. The client request will be made if the server allows the methods and headers in the response. In this scenario, the browser sends headers to the server using the OPTIONS method that specifies the methods and headers it intends to use in the actual request. The preflight request is a security measure to protect servers from the greater flexibility afforded under CORS. This is used to determine whether they will be allowed to perform a specific cross-domain request, especially one that contains non-standard HTTP methods or headers that can modify data. The CORS specification includes the possibility for browsers to perform a “preflight request” to a server via the OPTIONS method. This header is returned by servers when a cross-origin request is allowed, along with the conditions under which it is permitted. One of the protocol headers used in CORS is the Access-Control-Allow-Origin header. A poor cross-origin resource sharing setup may, in fact, make cross-site request forgery (CSRF) and cross-site scripting (XSS) attacks easier, which is why it must be understood and implemented well. The CORS policy does not protect against cross-origin attacks and may even enable them under certain conditions.

As part of the CORS response, a server can also inform a client if cookies or authentication data can be sent with a request. This controlled access is achieved via HTTP headers and the instructions contained therein. Depending on the setup, CORS allows or disallows access to resources that are located outside of a domain from which resources were initially provided.ĬORS is a way of relaxing the same-origin policy (SOP) to enable controlled access to one website domain from another via the use of HTTP requests. Origin, in this case, includes both the port, hostname, and scheme associated with a request.

Cross-Origin Resource Sharing (CORS) is a header-based mechanism that specifies how web browsers and servers interact and determines the safety of cross-origin HTTP requests and data transfers.

Access control allow origin php