Http proxy server in Go

http-proxy.go

package main

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

type _ReqRes struct {
	Request  *http.Request
	Response *http.Response
}

func main() {
	var ch = make(chan *_ReqRes, 10)

	http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
		req2, err := http.NewRequest(req.Method, req.RequestURI, req.Body)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		defer req2.Body.Close()

		for k, v := range req.Header {
			req2.Header.Set(k, v[0])
		}

		res2, err := (&http.Client{}).Do(req2)
		if err != nil { // either GET or POST
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		defer res2.Body.Close()

		for k, v := range res2.Header {
			w.Header().Set(k, v[0])
		}
		w.WriteHeader(res2.StatusCode)
		io.Copy(w, res2.Body)

		ch <- &_ReqRes{req, res2}
	})

	go func() { // console printer
		for {
			select {
			case reqRes := <-ch:
				fmt.Printf("%v %v\n", reqRes.Request.Method, reqRes.Request.RequestURI)
				for k, v := range reqRes.Request.Header {
					fmt.Println(k, ":", v)
				}
				fmt.Println("==============================")
				fmt.Printf("HTTP/1.1 %v\n", reqRes.Response.Status)
				for k, v := range reqRes.Response.Header {
					fmt.Println(k, ":", v)
				}
				fmt.Println(reqRes.Response.Body)
				fmt.Println("==============================")
			}
		}
	}()

	fmt.Println("==============================")
	fmt.Println("init")
	fmt.Println("==============================")

	err := http.ListenAndServe(":12345", nil)
	if err != nil {
		log.Fatal("ListenAndServe: ", err.Error())
	}
}