How to implement HTTP proxy function through http.Transport in Go?

How to implement HTTP proxy function through http.Transport in Go?

HTTP proxy is a commonly used network proxy technology that can forward network requests through a proxy server to protect the client's privacy and improve access speed. In Go language, you can use http.Transport to implement HTTP proxy function.

The working principle of the HTTP proxy server is to receive the client's HTTP request, forward it to the real target server, and then return the result to the client after the target server responds. In Go, we can create an http.Transport instance with proxy functionality by customizing http.RoundTripper.

The following is a sample code that demonstrates how to use http.Transport to implement the HTTP proxy function in Go:

package main

import (
    "fmt"
    "net/http"
    "net/url"
)

type ProxyTransport struct {
    ProxyUrl *url.URL
    Transport http.RoundTripper
}

func (t *ProxyTransport) RoundTrip(req *http.Request) (*http.Response, error) {
    req.URL.Scheme = t.ProxyUrl.Scheme
    req.URL.Host = t.ProxyUrl.Host

    return t.Transport.RoundTrip(req)
}

func main() {
    // 设置代理服务器的地址
    proxyUrl, _ := url.Parse("http://proxy.example.com:8080")

    // 创建一个带有代理功能的http.Transport实例
    transport := &ProxyTransport{
        ProxyUrl: proxyUrl,
        Transport: http.DefaultTransport,
    }

    // 创建一个http.Client实例，并设置Transport为代理功能的transport
    client := &http.Client{
        Transport: transport,
    }

    // 发送一个GET请求，并输出响应结果
    resp, err := client.Get("http://www.example.com")
    if err != nil {
        fmt.Println("Error:", err)
        return
    }
    defer resp.Body.Close()

    fmt.Println("Response status:", resp.Status)
}

In the above sample code, we first define a file named ## The type of #ProxyTransport, which implements the http.RoundTripper interface, is used to handle HTTP requests. In the RoundTrip method, we modify the requested URL to the address of the proxy server and call the Transport.RoundTrip method to send the request.

main function, we first create a ProxyUrl pointing to the address of the proxy server, and then create a ProxyTransport instance to proxy The server address and the default http.Transport are passed to it. Next, we create an http.Client instance and set Transport to the transport of the proxy function. Finally, we use the client.Get method to send a GET request and print out the response status code.

http.Transport to implement the HTTP proxy function. By customizing the ProxyTransport type, we can flexibly control the forwarding process of HTTP requests. In actual applications, we can modify the logic of the RoundTrip method as needed to achieve more complex proxy functions.

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