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3min快速掌握Go语言正/反向代理的姿势 - 博客猿马甲哥

 2 years ago
source link: https://www.cnblogs.com/JulianHuang/p/16867844.html
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3min快速掌握Go语言正/反向代理的姿势

先重温一下什么叫反向代理，正向代理。

鹅厂二面，nginx回忆录

所谓正向，反向代理取决于代理的是出站请求，还是入站请求。

正向代理： 代理的出站请求， 客户端能感知到代理程序，架构上距离客户端更近。
反向代理： 代理的是入站请求，客户端认为代理程序就是服务器，客户端感知不到代理逻辑，架构上距离服务端更近。

478ca8af7af74b22bc55b6391ef77398~tplv-k3u1fbpfcp-zoom-1.image

前几天利用golang实现了反向代理程序，引出了Host请求头在反代中的关键作用。

e5a98446e7e04eb89a5529baff29dd71~tplv-k3u1fbpfcp-zoom-1.image

对于proxy.com的请求，都被透明无感代理到A.com

package main

import (
	"fmt"
	"log"
	"net/http"
	"net/http/httputil"
)

func ReverseProxyHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Println("receive a request from:", r.RemoteAddr, r.Header)

	target := "www.baidu.com"
	director := func(req *http.Request) {
		req.URL.Scheme = "https"
		req.URL.Host = target
		req.Host = target
	}
	proxy := &httputil.ReverseProxy{Director: director}
	proxy.ServeHTTP(w, r)
}

func main() {
	fmt.Printf("Starting server at port 8080\n")
	if err := http.ListenAndServe(":8080", http.HandlerFunc(ReverseProxyHandler)); err != nil {
		log.Fatal(err)
	}
}

这几天刚好遇到了一个正常代理的case， 简单记录一下。

4945be185c014718ac7d5cd87ab04a13~tplv-k3u1fbpfcp-zoom-1.image
package main

import (
	"fmt"
	"log"
	"net/http"
	"net/http/httputil"
)

func ProxyHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Printf("receive a request from {0}  {1}: \n", r.RemoteAddr, r.Header)
	if r.Host != "localhost:8080" {
		director := func(req *http.Request) {
			req.URL.Scheme = "http"
			req.URL.Host = r.Host
			req.Host = r.Host
		}
		proxy := &httputil.ReverseProxy{Director: director}
		proxy.ServeHTTP(w, r)
	} else {
		http.NotFound(w, r)
	}
}

func main() {
	if err := http.ListenAndServe(":8080", http.HandlerFunc(ProxyHandler)); err != nil {
		log.Fatal(err)
	}
}

其中要注意的就是，正向代理式要规避死循环代理。

使用该服务作为代理程序，将可以出站访问任何地址。

使用时，针对httpclient设置proxy

//adding the proxy settings to the Transport object
	transport := &http.Transport{
		Proxy: http.ProxyURL(proxyURL),
	}

	//adding the Transport object to the http Client
	client := &http.Client{
		Transport: transport,
	}

下面使用curl指令演示（-x 后接代理地址）
curl -x 127.0.0.1:8080 www.baidu.com

e4c084ad78fa45cfb90ab9d2c04e58ba~tplv-k3u1fbpfcp-zoom-1.image

GO快闪#

本文总结了go语言正反向代理的姿势。


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