Stupid http proxy

stupidproxy.go

package main

import (
	"flag"
	"log"
	"net/http"
	"net/http/httputil"
	"strings"
)

var (
	flagLog     = flag.Bool("log", true, "Log requests")
	flagBind    = flag.String("bind", ":8888", "Address to bind to")
	flagTarget  = flag.String("target", "localhost:8180", "Target address")
	flagHeaders = flag.String("headers", "", "Headers to add in transit \"k=v|...\"")
)

func getHeaders() map[string]string {
	if *flagHeaders == "" {
		return nil
	}

	ret := make(map[string]string)
	parts := strings.Split(*flagHeaders, "|")
	for _, part := range parts {
		eq := strings.IndexByte(part, '=')
		if eq == -1 {
			continue
		}
		key := part[:eq]
		val := part[eq+1:]
		ret[key] = val
	}

	return ret
}

func main() {
	flag.Parse()

	headers := getHeaders()
	p := httputil.ReverseProxy{
		Director: func(req *http.Request) {
			if *flagLog {
				log.Printf("%s %s %s", req.Method, req.Host, req.RequestURI)
			}
			req.URL.Scheme = "http"
			req.URL.Host = *flagTarget
			for k, v := range headers {
				k = http.CanonicalHeaderKey(k)
				switch k {
				case "Host":
					req.Host = v
				case "Connection":
					if v == "close" {
						req.Close = true
					} else {
						req.Header.Set(k, v)
					}
				default:
					req.Header.Set(k, v)
				}
			}
		},
	}

	log.Fatalln(http.ListenAndServe(*flagBind, &p))
}