A web server that occasionally closes connections (after serving 400).

shutter.go

package main

import (
	"flag"
	"fmt"
	"math/rand"
	"net/http"
	"os"
)

type (
	shutter struct {
		// rate of terminal requests, on [0.0, 1.0]
		TerminalRate float64
	}
)

func (srv *shutter) ShouldTerminate() bool {
	return (1.0 - rand.Float64()) <= srv.TerminalRate
}

func (srv *shutter) serveTerminal(w http.ResponseWriter) {
	hj, ok := w.(http.Hijacker)
	if !ok {
		fmt.Fprintln(os.Stderr, "unhijackale")
		http.Error(w, "webserver doesn't support hijacking", http.StatusInternalServerError)
		return
	}
	conn, bufrw, err := hj.Hijack()
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	bufrw.WriteString("HTTP/1.1 400 Ugly Request\r\n")
	bufrw.WriteString("Connection: close\r\n")
	bufrw.WriteString("Transfer-encoding: chunked\r\n")
	bufrw.WriteString("\r\n")
	bufrw.Flush()
	bufrw.WriteString("0\r\n")
	bufrw.WriteString("\r\n")
	bufrw.Flush()
	conn.Close()
}

func (srv *shutter) serveTypical(w http.ResponseWriter) {
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	w.WriteHeader(http.StatusOK)
}

func (srv *shutter) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	req.Body.Close()
	if srv.ShouldTerminate() {
		fmt.Printf("* %s %s%s \n", req.Method, req.Host, req.URL)
		srv.serveTerminal(w)
	} else {
		fmt.Printf("- %s %s%s \n", req.Method, req.Host, req.URL)
		srv.serveTypical(w)
	}
}

//
// main
//

func dieIf(err error) {
	if err == nil {
		return
	}
	fmt.Fprintf(os.Stderr, "Error: %s. Try --help for help.\n", err)
	os.Exit(-1)
}

func main() {
	addr := flag.String("srv", ":8080", "TCP address to listen on (in host:port form)")
	flag.Parse()
	if flag.NArg() != 0 {
		dieIf(fmt.Errorf("expecting zero arguments but got %d", flag.NArg()))
	}

	server := &http.Server{
		Addr:    *addr,
		Handler: &shutter{0.1},
	}
	dieIf(server.ListenAndServe())
}