Go语言写的简单HTTP反向代理

http-reverse-proxy.go

package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"time"
)

func main() {
	log.Fatal(http.ListenAndServe(":3000", proxy("http://www.rabbitpre.com", time.Second*10)))
}

func copyHeader(dest, src http.Header) {
	for k, vv := range src {
		for _, v := range vv {
			dest.Add(k, v)
		}
	}
}

func responseError(w http.ResponseWriter, err error) {
	w.WriteHeader(http.StatusInternalServerError)
	fmt.Fprint(w, err)
}

func proxy(target string, timeout time.Duration) http.Handler {
	urlInfo, err := url.Parse(target)
	if err != nil {
		panic(err)
	}
	client := &http.Client{
		Timeout: timeout,
	}
	log.Printf("init: target=%s timeout=%d", target, timeout)
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer r.Body.Close()
		log.Printf("%s %s %d\n", r.Method, r.RequestURI, r.ContentLength)
		log.Printf("  - proxy: %s\n", target+r.RequestURI)
		if err != nil {
			responseError(w, err)
			return
		}
		req, err := http.NewRequest(r.Method, target+r.RequestURI, r.Body)
		if err != nil {
			responseError(w, err)
			return
		}
		copyHeader(req.Header, r.Header)
		req.Header.Set("Host", urlInfo.Host)
		resp, err := client.Do(req)
		if err != nil {
			responseError(w, err)
			return
		}
		defer resp.Body.Close()
		log.Printf("  - response: %d %s %d\n", resp.StatusCode, resp.Header.Get("Content-Type"), resp.ContentLength)
		copyHeader(w.Header(), resp.Header)
		w.WriteHeader(resp.StatusCode)
		io.Copy(w, resp.Body)
	})
}