toolkit/cmd/httpcat/main.go

package main

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

var (
	ports = flag.String("ports", "", "comma-separated list of ports to listen on")
)

type CatHandler struct{}

var _ http.Handler = &CatHandler{}

func (cs *CatHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	log.Printf("[%s] %s %s", req.Host, req.Method, req.URL.Path)

	w.Write([]byte(fmt.Sprintf("HTTP1.1 %s %s\n", req.Method, req.URL.Path)))
	for k, v := range req.Header {
		w.Write([]byte(fmt.Sprintf("%s: %s\n", k, strings.Join(v, ", "))))
	}
	w.Write([]byte{'\n'})

	if req.Body != nil {
		io.Copy(w, req.Body)
	}
}

func main() {
	flag.Parse()

	errch := make(chan error)
	done := make(chan struct{})
	for _, p := range strings.Split(*ports, ",") {
		port := strings.TrimSpace(p)
		if port[0] != ':' {
			port = ":" + port
		}
		go func() {
			log.Printf("listening on %s\n", port)
			if err := http.ListenAndServe(port, new(CatHandler)); err != nil {
				log.Println(err)
				errch <- err
			}
		}()
	}

	go func() {
		<-errch
		done <- struct{}{}
	}()

	<-done
}