How to set up cross-domain php project

Cross-Origin Resource Sharing (CORS) is a Web technology that allows browsers to send AJAX requests to different domains when requesting resources. When using a web service, CORS allows the browser to request data from another domain. This article will introduce how to set up cross-domain access in PHP projects.

What is cross-domain?

Cross-domain refers to in web development when a script executed by the browser attempts to access a different origin than the server the page came from. For example, on the web page of www.example.com, if the script attempts to access the server of http://www.example.org, it is called a cross-domain request.

Why do we need to set up cross-domain?

Web browsers implement the Same-Origin Policy, which is a basic web security policy that restricts a script to only access content from the same origin site. A homologous site refers to a site with the same protocol, domain name, and port . Without the restriction of the same-origin policy, cross-domain requests can easily attack the user's account. For example, if you purchase a book online, a malicious script can easily access your account from a different domain and use your account to make a payment.

How to set up cross-domain?

In PHP projects, you can build cross-origin requests (CORS) by setting response headers.

1. Access-Control-Allow-Origin

Set the "Access-Control-Allow-Origin" response header, which allows requests from a certain domain. For example, if an AJAX request requires sending the request from "http://localhost:3000", then you can add the following line to the server's response header.

header("Access-Control-Allow-Origin:http://localhost:3000");

2. Access-Control-Allow-Headers

Setting Allow-Origin is to allow cross-domain requests for a certain domain name, and Access-Control-Allow-Headers also needs to be set. , to allow custom request headers. For example, if the AJAX request wants to send a custom request header "X-Custom-Header", you need to add the following line to the response header.

header("Access-Control-Allow-Headers: X-Custom-Header");

3. Access-Control-Allow-Methods

Access-Control-Allow-Methods Specifies which request methods are allowed by adding the following line to the response header, For example, this example setup allows GET and POST methods.

header('Access-Control-Allow-Methods: GET, POST');

4. Access-Control-Allow-Credentials

If cookies need to be sent, Access-Control-Allow-Credentials should be set to "true". For example, ask the browser to request a cookie.

header('Access-Control-Allow-Credentials: true');

Summary

Implementing cross-domain requests (CORS) in PHP projects requires setting response headers by setting Access-Control-Allow-Origin, Access-Control-Allow-Headers, Access- Key response headers such as Control-Allow-Methods and Access-Control-Allow-Credentials allow the browser to allow cross-domain requests when sending requests.

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