💩 server

poo_server.go

// HTTP server which periodically emits a message, in this case, "💩 ".
//
// Idea taken from http://robpike.io/
// Test with: curl -i -N http://localhost:8080

package main

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

const (
	addr     = ":8080"
	interval = 2 // seconds
	output   = "💩 "
)

func main() {
	http.HandleFunc("/", handler)
	log.Printf("Starting server on %s", addr)
	if err := http.ListenAndServe(addr, nil); err != nil {
		log.Fatal("ListenAndServe error: ", err)
	}
}

// handler hijacks the HTTP connection and periodically sends a "chunked" message
func handler(w http.ResponseWriter, req *http.Request) {
	hj, ok := w.(http.Hijacker)
	if !ok {
		http.Error(w, "webserver doesn't support hijacking", http.StatusInternalServerError)
		return
	}
	conn, bufrw, err := hj.Hijack()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer conn.Close()
	if err = writeChunkedHeader(bufrw); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	bufrw.Flush()

	chunk := []byte(fmt.Sprintf("%x\r\n%s\r\n", len(output), output))
	for _ = range time.NewTicker(interval * time.Second).C {
		if _, err = bufrw.Write(chunk); err != nil {
			return
		}
		bufrw.Flush()
	}
}

const (
	headerTimeFormat = "Mon, 02 Jan 2006 15:04:05 GMT"
	header           = `HTTP/1.1 200 OK
Date: %s
Content-Type: text/plain; charset=UTF-8
Transfer-Encoding: chunked

`
)

// writeChunckedHeader returns an HTTP 1.1 header with transfer encoding set to chunked.
func writeChunkedHeader(w io.Writer) error {
	_, err := w.Write([]byte(
		fmt.Sprintf(header, time.Now().UTC().Format(headerTimeFormat)),
	))
	return err
}