Understand PHP proxy

Create a PHP file and write the proxy server code locally or on the server. Get the request, and use $_SERVER[' request _URI'] and $_SERVER[' request _ method'] to get the request URI and request method of the client. Select the proxy server, and select the proxy server to use according to the domain name or other rules in the request URI. Send a request, and use the cURL library or other HTTP client libraries to send a request to the proxy server. Receive the response and wait for the proxy server to return the response. Output the response, that is, output the response header and response body to the client in the corresponding format. 

The application scenarios of PHP proxy include:

PHP proxy is a technology implemented on the server side, which allows PHP scripts to act as intermediaries between the client and the target server. Through the PHP proxy, you can access other services or sites and pass the request response back to the client. The main function of proxy server is to hide the real communication details between client and server, thus improving network security. Proxy servers are divided into forward proxy and reverse proxy. Forward proxy means that the client requests the proxy server to access other services or sites, while reverse proxy means that when the client requests the service site, it is redirected to the proxy server, and then the proxy server forwards the request to the real server.

The steps for PHP to implement a proxy server usually include:

Remote Proxy: Provides local proxies for objects located in different address spaces, so that clients can access remote objects just like local objects.

Virtual proxy: create expensive objects as needed, store instantiation operations of instantiated objects through proxies, and instantiate them only when really needed, thus saving system resources.

Protection proxy: controls access to the original object, which can be used in scenarios such as permission control.

Intelligent reference proxy: when accessing an object, attach some extra operations, such as recording access logs and handling abnormal situations.

The working principle of PHP proxy involves using cURL library or other HTTP client libraries to send requests to proxy servers and receive responses. When sending a request, you need to pay attention to passing the client request method, request header and request body to the proxy server. When receiving a response, you need to pay attention to passing the response header and response body returned by the proxy server back to the client.

In practical application, it can be modified and expanded as needed to meet various needs. For example, you can use PHP to implement a reverse proxy server and forward all API paths requested by the client to the specified server. In addition, you can also use PHP to realize efficient proxy forwarding function and deeply understand proxy_pass configuration and optimization skills.

Generally speaking, PHP proxy is a powerful tool, which can help developers realize the forwarding and processing of requests on the server side and improve the flexibility and security of applications.