http2/h2demo/h2demo.go - net - Git at Google

 // Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // +build h2demo

 package main

 import (
 	"bytes"
 	"crypto/tls"
 	"flag"
 	"fmt"
 	"hash/crc32"
 	"image"
 	"image/jpeg"
 	"io"
 	"io/ioutil"
 	"log"
 	"net"
 	"net/http"
 	"os"
 	"path"
 	"regexp"
 	"runtime"
 	"strconv"
 	"strings"
 	"sync"
 	"time"

 	"go4.org/syncutil/singleflight"
 	"golang.org/x/crypto/acme/autocert"
 	"golang.org/x/net/http2"
 )

 var (
 	prod = flag.Bool("prod", false, "Whether to configure itself to be the production http2.golang.org server.")

 	httpsAddr = flag.String("https_addr", "localhost:4430", "TLS address to listen on ('host:port' or ':port'). Required.")
 	httpAddr  = flag.String("http_addr", "", "Plain HTTP address to listen on ('host:port', or ':port'). Empty means no HTTP.")

 	hostHTTP  = flag.String("http_host", "", "Optional host or host:port to use for http:// links to this service. By default, this is implied from -http_addr.")
 	hostHTTPS = flag.String("https_host", "", "Optional host or host:port to use for http:// links to this service. By default, this is implied from -https_addr.")
 )

 func homeOldHTTP(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, `<html>
 <body>
 <h1>Go + HTTP/2</h1>
 <p>Welcome to <a href="https://golang.org/">the Go language</a>'s <a href="https://http2.github.io/">HTTP/2</a> demo & interop server.</p>
 <p>Unfortunately, you're <b>not</b> using HTTP/2 right now. To do so:</p>
 <ul>
    <li>Use Firefox Nightly or go to <b>about:config</b> and enable "network.http.spdy.enabled.http2draft"</li>
    <li>Use Google Chrome Canary and/or go to <b>chrome://flags/#enable-spdy4</b> to <i>Enable SPDY/4</i> (Chrome's name for HTTP/2)</li>
 </ul>
 <p>See code & instructions for connecting at <a href="https://github.com/golang/net/tree/master/http2">https://github.com/golang/net/tree/master/http2</a>.</p>

 </body></html>`)
 }

 func home(w http.ResponseWriter, r *http.Request) {
 	if r.URL.Path != "/" {
 		http.NotFound(w, r)
 		return
 	}
 	io.WriteString(w, `<html>
 <body>
 <h1>Go + HTTP/2</h1>

 <p>Welcome to <a href="https://golang.org/">the Go language</a>'s <a
 href="https://http2.github.io/">HTTP/2</a> demo & interop server.</p>

 <p>Congratulations, <b>you're using HTTP/2 right now</b>.</p>

 <p>This server exists for others in the HTTP/2 community to test their HTTP/2 client implementations and point out flaws in our server.</p>

 <p>
 The code is at <a href="https://golang.org/x/net/http2">golang.org/x/net/http2</a> and
 is used transparently by the Go standard library from Go 1.6 and later.
 </p>

 <p>Contact info: <i>bradfitz@golang.org</i>, or <a
 href="https://golang.org/s/http2bug">file a bug</a>.</p>

 <h2>Handlers for testing</h2>
 <ul>
   <li>GET <a href="/reqinfo">/reqinfo</a> to dump the request + headers received</li>
   <li>GET <a href="/clockstream">/clockstream</a> streams the current time every second</li>
   <li>GET <a href="/gophertiles">/gophertiles</a> to see a page with a bunch of images</li>
   <li>GET <a href="/serverpush">/serverpush</a> to see a page with server push</li>
   <li>GET <a href="/file/gopher.png">/file/gopher.png</a> for a small file (does If-Modified-Since, Content-Range, etc)</li>
   <li>GET <a href="/file/go.src.tar.gz">/file/go.src.tar.gz</a> for a larger file (~10 MB)</li>
   <li>GET <a href="/redirect">/redirect</a> to redirect back to / (this page)</li>
   <li>GET <a href="/goroutines">/goroutines</a> to see all active goroutines in this server</li>
   <li>PUT something to <a href="/crc32">/crc32</a> to get a count of number of bytes and its CRC-32</li>
   <li>PUT something to <a href="/ECHO">/ECHO</a> and it will be streamed back to you capitalized</li>
 </ul>

 </body></html>`)
 }

 func reqInfoHandler(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "text/plain")
 	fmt.Fprintf(w, "Method: %s\n", r.Method)
 	fmt.Fprintf(w, "Protocol: %s\n", r.Proto)
 	fmt.Fprintf(w, "Host: %s\n", r.Host)
 	fmt.Fprintf(w, "RemoteAddr: %s\n", r.RemoteAddr)
 	fmt.Fprintf(w, "RequestURI: %q\n", r.RequestURI)
 	fmt.Fprintf(w, "URL: %#v\n", r.URL)
 	fmt.Fprintf(w, "Body.ContentLength: %d (-1 means unknown)\n", r.ContentLength)
 	fmt.Fprintf(w, "Close: %v (relevant for HTTP/1 only)\n", r.Close)
 	fmt.Fprintf(w, "TLS: %#v\n", r.TLS)
 	fmt.Fprintf(w, "\nHeaders:\n")
 	r.Header.Write(w)
 }

 func crcHandler(w http.ResponseWriter, r *http.Request) {
 	if r.Method != "PUT" {
 		http.Error(w, "PUT required.", 400)
 		return
 	}
 	crc := crc32.NewIEEE()
 	n, err := io.Copy(crc, r.Body)
 	if err == nil {
 		w.Header().Set("Content-Type", "text/plain")
 		fmt.Fprintf(w, "bytes=%d, CRC32=%x", n, crc.Sum(nil))
 	}
 }

 type capitalizeReader struct {
 	r io.Reader
 }

 func (cr capitalizeReader) Read(p []byte) (n int, err error) {
 	n, err = cr.r.Read(p)
 	for i, b := range p[:n] {
 		if b >= 'a' && b <= 'z' {
 			p[i] = b - ('a' - 'A')
 		}
 	}
 	return
 }

 type flushWriter struct {
 	w io.Writer
 }

 func (fw flushWriter) Write(p []byte) (n int, err error) {
 	n, err = fw.w.Write(p)
 	if f, ok := fw.w.(http.Flusher); ok {
 		f.Flush()
 	}
 	return
 }

 func echoCapitalHandler(w http.ResponseWriter, r *http.Request) {
 	if r.Method != "PUT" {
 		http.Error(w, "PUT required.", 400)
 		return
 	}
 	io.Copy(flushWriter{w}, capitalizeReader{r.Body})
 }

 var (
 	fsGrp   singleflight.Group
 	fsMu    sync.Mutex // guards fsCache
 	fsCache = map[string]http.Handler{}
 )

 // fileServer returns a file-serving handler that proxies URL.
 // It lazily fetches URL on the first access and caches its contents forever.
 func fileServer(url string, latency time.Duration) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if latency > 0 {
 			time.Sleep(latency)
 		}
 		hi, err := fsGrp.Do(url, func() (interface{}, error) {
 			fsMu.Lock()
 			if h, ok := fsCache[url]; ok {
 				fsMu.Unlock()
 				return h, nil
 			}
 			fsMu.Unlock()

 			res, err := http.Get(url)
 			if err != nil {
 				return nil, err
 			}
 			defer res.Body.Close()
 			slurp, err := ioutil.ReadAll(res.Body)
 			if err != nil {
 				return nil, err
 			}

 			modTime := time.Now()
 			var h http.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 				http.ServeContent(w, r, path.Base(url), modTime, bytes.NewReader(slurp))
 			})
 			fsMu.Lock()
 			fsCache[url] = h
 			fsMu.Unlock()
 			return h, nil
 		})
 		if err != nil {
 			http.Error(w, err.Error(), 500)
 			return
 		}
 		hi.(http.Handler).ServeHTTP(w, r)
 	})
 }

 func clockStreamHandler(w http.ResponseWriter, r *http.Request) {
 	clientGone := w.(http.CloseNotifier).CloseNotify()
 	w.Header().Set("Content-Type", "text/plain")
 	ticker := time.NewTicker(1 * time.Second)
 	defer ticker.Stop()
 	fmt.Fprintf(w, "# ~1KB of junk to force browsers to start rendering immediately: \n")
 	io.WriteString(w, strings.Repeat("# xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\n", 13))

 	for {
 		fmt.Fprintf(w, "%v\n", time.Now())
 		w.(http.Flusher).Flush()
 		select {
 		case <-ticker.C:
 		case <-clientGone:
 			log.Printf("Client %v disconnected from the clock", r.RemoteAddr)
 			return
 		}
 	}
 }

 func registerHandlers() {
 	tiles := newGopherTilesHandler()
 	push := newPushHandler()

 	mux2 := http.NewServeMux()
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		switch {
 		case r.URL.Path == "/gophertiles":
 			tiles.ServeHTTP(w, r) // allow HTTP/2 + HTTP/1.x
 			return
 		case strings.HasPrefix(r.URL.Path, "/serverpush"):
 			push.ServeHTTP(w, r) // allow HTTP/2 + HTTP/1.x
 			return
 		case r.TLS == nil: // do not allow HTTP/1.x for anything else
 			http.Redirect(w, r, "https://"+httpsHost()+"/", http.StatusFound)
 			return
 		}
 		if r.ProtoMajor == 1 {
 			if r.URL.Path == "/reqinfo" {
 				reqInfoHandler(w, r)
 				return
 			}
 			homeOldHTTP(w, r)
 			return
 		}
 		mux2.ServeHTTP(w, r)
 	})
 	mux2.HandleFunc("/", home)
 	mux2.Handle("/file/gopher.png", fileServer("https://golang.org/doc/gopher/frontpage.png", 0))
 	mux2.Handle("/file/go.src.tar.gz", fileServer("https://storage.googleapis.com/golang/go1.4.1.src.tar.gz", 0))
 	mux2.HandleFunc("/reqinfo", reqInfoHandler)
 	mux2.HandleFunc("/crc32", crcHandler)
 	mux2.HandleFunc("/ECHO", echoCapitalHandler)
 	mux2.HandleFunc("/clockstream", clockStreamHandler)
 	mux2.Handle("/gophertiles", tiles)
 	mux2.HandleFunc("/redirect", func(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, "/", http.StatusFound)
 	})
 	stripHomedir := regexp.MustCompile(`/(Users|home)/\w+`)
 	mux2.HandleFunc("/goroutines", func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 		buf := make([]byte, 2<<20)
 		w.Write(stripHomedir.ReplaceAll(buf[:runtime.Stack(buf, true)], nil))
 	})
 }

 var pushResources = map[string]http.Handler{
 	"/serverpush/static/jquery.min.js": fileServer("https://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js", 100*time.Millisecond),
 	"/serverpush/static/godocs.js":     fileServer("https://golang.org/lib/godoc/godocs.js", 100*time.Millisecond),
 	"/serverpush/static/playground.js": fileServer("https://golang.org/lib/godoc/playground.js", 100*time.Millisecond),
 	"/serverpush/static/style.css":     fileServer("https://golang.org/lib/godoc/style.css", 100*time.Millisecond),
 }

 func newPushHandler() http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		for path, handler := range pushResources {
 			if r.URL.Path == path {
 				handler.ServeHTTP(w, r)
 				return
 			}
 		}

 		cacheBust := time.Now().UnixNano()
 		if pusher, ok := w.(http.Pusher); ok {
 			for path := range pushResources {
 				url := fmt.Sprintf("%s?%d", path, cacheBust)
 				if err := pusher.Push(url, nil); err != nil {
 					log.Printf("Failed to push %v: %v", path, err)
 				}
 			}
 		}
 		time.Sleep(100 * time.Millisecond) // fake network latency + parsing time
 		if err := pushTmpl.Execute(w, struct {
 			CacheBust int64
 			HTTPSHost string
 			HTTPHost  string
 		}{
 			CacheBust: cacheBust,
 			HTTPSHost: httpsHost(),
 			HTTPHost:  httpHost(),
 		}); err != nil {
 			log.Printf("Executing server push template: %v", err)
 		}
 	})
 }

 func newGopherTilesHandler() http.Handler {
 	const gopherURL = "https://blog.golang.org/go-programming-language-turns-two_gophers.jpg"
 	res, err := http.Get(gopherURL)
 	if err != nil {
 		log.Fatal(err)
 	}
 	if res.StatusCode != 200 {
 		log.Fatalf("Error fetching %s: %v", gopherURL, res.Status)
 	}
 	slurp, err := ioutil.ReadAll(res.Body)
 	res.Body.Close()
 	if err != nil {
 		log.Fatal(err)
 	}
 	im, err := jpeg.Decode(bytes.NewReader(slurp))
 	if err != nil {
 		if len(slurp) > 1024 {
 			slurp = slurp[:1024]
 		}
 		log.Fatalf("Failed to decode gopher image: %v (got %q)", err, slurp)
 	}

 	type subImager interface {
 		SubImage(image.Rectangle) image.Image
 	}
 	const tileSize = 32
 	xt := im.Bounds().Max.X / tileSize
 	yt := im.Bounds().Max.Y / tileSize
 	var tile [][][]byte // y -> x -> jpeg bytes
 	for yi := 0; yi < yt; yi++ {
 		var row [][]byte
 		for xi := 0; xi < xt; xi++ {
 			si := im.(subImager).SubImage(image.Rectangle{
 				Min: image.Point{xi * tileSize, yi * tileSize},
 				Max: image.Point{(xi + 1) * tileSize, (yi + 1) * tileSize},
 			})
 			buf := new(bytes.Buffer)
 			if err := jpeg.Encode(buf, si, &jpeg.Options{Quality: 90}); err != nil {
 				log.Fatal(err)
 			}
 			row = append(row, buf.Bytes())
 		}
 		tile = append(tile, row)
 	}
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		ms, _ := strconv.Atoi(r.FormValue("latency"))
 		const nanosPerMilli = 1e6
 		if r.FormValue("x") != "" {
 			x, _ := strconv.Atoi(r.FormValue("x"))
 			y, _ := strconv.Atoi(r.FormValue("y"))
 			if ms <= 1000 {
 				time.Sleep(time.Duration(ms) * nanosPerMilli)
 			}
 			if x >= 0 && x < xt && y >= 0 && y < yt {
 				http.ServeContent(w, r, "", time.Time{}, bytes.NewReader(tile[y][x]))
 				return
 			}
 		}
 		io.WriteString(w, "<html><body onload='showtimes()'>")
 		fmt.Fprintf(w, "A grid of %d tiled images is below. Compare:<p>", xt*yt)
 		for _, ms := range []int{0, 30, 200, 1000} {
 			d := time.Duration(ms) * nanosPerMilli
 			fmt.Fprintf(w, "[<a href='https://%s/gophertiles?latency=%d'>HTTP/2, %v latency</a>] [<a href='http://%s/gophertiles?latency=%d'>HTTP/1, %v latency</a>]<br>\n",
 				httpsHost(), ms, d,
 				httpHost(), ms, d,
 			)
 		}
 		io.WriteString(w, "<p>\n")
 		cacheBust := time.Now().UnixNano()
 		for y := 0; y < yt; y++ {
 			for x := 0; x < xt; x++ {
 				fmt.Fprintf(w, "<img width=%d height=%d src='/gophertiles?x=%d&y=%d&cachebust=%d&latency=%d'>",
 					tileSize, tileSize, x, y, cacheBust, ms)
 			}
 			io.WriteString(w, "<br/>\n")
 		}
 		io.WriteString(w, `<p><div id='loadtimes'></div></p>
 <script>
 function showtimes() {
 	var times = 'Times from connection start:<br>'
 	times += 'DOM loaded: ' + (window.performance.timing.domContentLoadedEventEnd - window.performance.timing.connectStart) + 'ms<br>'
 	times += 'DOM complete (images loaded): ' + (window.performance.timing.domComplete - window.performance.timing.connectStart) + 'ms<br>'
 	document.getElementById('loadtimes').innerHTML = times
 }
 </script>
 <hr><a href='/'>&lt;&lt Back to Go HTTP/2 demo server</a></body></html>`)
 	})
 }

 func httpsHost() string {
 	if *hostHTTPS != "" {
 		return *hostHTTPS
 	}
 	if v := *httpsAddr; strings.HasPrefix(v, ":") {
 		return "localhost" + v
 	} else {
 		return v
 	}
 }

 func httpHost() string {
 	if *hostHTTP != "" {
 		return *hostHTTP
 	}
 	if v := *httpAddr; strings.HasPrefix(v, ":") {
 		return "localhost" + v
 	} else {
 		return v
 	}
 }

 func serveProdTLS() error {
 	const cacheDir = "/var/cache/autocert"
 	if err := os.MkdirAll(cacheDir, 0700); err != nil {
 		return err
 	}
 	m := autocert.Manager{
 		Cache:      autocert.DirCache(cacheDir),
 		Prompt:     autocert.AcceptTOS,
 		HostPolicy: autocert.HostWhitelist("http2.golang.org"),
 	}
 	srv := &http.Server{
 		TLSConfig: &tls.Config{
 			GetCertificate: m.GetCertificate,
 		},
 	}
 	http2.ConfigureServer(srv, &http2.Server{
 		NewWriteScheduler: func() http2.WriteScheduler {
 			return http2.NewPriorityWriteScheduler(nil)
 		},
 	})
 	ln, err := net.Listen("tcp", ":443")
 	if err != nil {
 		return err
 	}
 	return srv.Serve(tls.NewListener(tcpKeepAliveListener{ln.(*net.TCPListener)}, srv.TLSConfig))
 }

 type tcpKeepAliveListener struct {
 	*net.TCPListener
 }

 func (ln tcpKeepAliveListener) Accept() (c net.Conn, err error) {
 	tc, err := ln.AcceptTCP()
 	if err != nil {
 		return
 	}
 	tc.SetKeepAlive(true)
 	tc.SetKeepAlivePeriod(3 * time.Minute)
 	return tc, nil
 }

 func serveProd() error {
 	errc := make(chan error, 2)
 	go func() { errc <- http.ListenAndServe(":80", nil) }()
 	go func() { errc <- serveProdTLS() }()
 	return <-errc
 }

 const idleTimeout = 5 * time.Minute
 const activeTimeout = 10 * time.Minute

 // TODO: put this into the standard library and actually send
 // PING frames and GOAWAY, etc: golang.org/issue/14204
 func idleTimeoutHook() func(net.Conn, http.ConnState) {
 	var mu sync.Mutex
 	m := map[net.Conn]*time.Timer{}
 	return func(c net.Conn, cs http.ConnState) {
 		mu.Lock()
 		defer mu.Unlock()
 		if t, ok := m[c]; ok {
 			delete(m, c)
 			t.Stop()
 		}
 		var d time.Duration
 		switch cs {
 		case http.StateNew, http.StateIdle:
 			d = idleTimeout
 		case http.StateActive:
 			d = activeTimeout
 		default:
 			return
 		}
 		m[c] = time.AfterFunc(d, func() {
 			log.Printf("closing idle conn %v after %v", c.RemoteAddr(), d)
 			go c.Close()
 		})
 	}
 }

 func main() {
 	var srv http.Server
 	flag.BoolVar(&http2.VerboseLogs, "verbose", false, "Verbose HTTP/2 debugging.")
 	flag.Parse()
 	srv.Addr = *httpsAddr
 	srv.ConnState = idleTimeoutHook()

 	registerHandlers()

 	if *prod {
 		*hostHTTP = "http2.golang.org"
 		*hostHTTPS = "http2.golang.org"
 		log.Fatal(serveProd())
 	}

 	url := "https://" + httpsHost() + "/"
 	log.Printf("Listening on " + url)
 	http2.ConfigureServer(&srv, &http2.Server{})

 	if *httpAddr != "" {
 		go func() {
 			log.Printf("Listening on http://" + httpHost() + "/ (for unencrypted HTTP/1)")
 			log.Fatal(http.ListenAndServe(*httpAddr, nil))
 		}()
 	}

 	go func() {
 		log.Fatal(srv.ListenAndServeTLS("server.crt", "server.key"))
 	}()
 	select {}
 }
	// Copyright 2014 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// +build h2demo

	package main

	import (
	"bytes"
	"crypto/tls"
	"flag"
	"fmt"
	"hash/crc32"
	"image"
	"image/jpeg"
	"io"
	"io/ioutil"
	"log"
	"net"
	"net/http"
	"os"
	"path"
	"regexp"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"

	"go4.org/syncutil/singleflight"
	"golang.org/x/crypto/acme/autocert"
	"golang.org/x/net/http2"
	)

	var (
	prod = flag.Bool("prod", false, "Whether to configure itself to be the production http2.golang.org server.")

	httpsAddr = flag.String("https_addr", "localhost:4430", "TLS address to listen on ('host:port' or ':port'). Required.")
	httpAddr = flag.String("http_addr", "", "Plain HTTP address to listen on ('host:port', or ':port'). Empty means no HTTP.")

	hostHTTP = flag.String("http_host", "", "Optional host or host:port to use for http:// links to this service. By default, this is implied from -http_addr.")
	hostHTTPS = flag.String("https_host", "", "Optional host or host:port to use for http:// links to this service. By default, this is implied from -https_addr.")
	)

	func homeOldHTTP(w http.ResponseWriter, r *http.Request) {
	io.WriteString(w, `<html>
	<body>
	<h1>Go + HTTP/2</h1>
	<p>Welcome to <a href="https://golang.org/">the Go language</a>'s <a href="https://http2.github.io/">HTTP/2</a> demo & interop server.</p>
	<p>Unfortunately, you're <b>not</b> using HTTP/2 right now. To do so:</p>
	<ul>
	<li>Use Firefox Nightly or go to <b>about:config</b> and enable "network.http.spdy.enabled.http2draft"</li>
	<li>Use Google Chrome Canary and/or go to <b>chrome://flags/#enable-spdy4</b> to <i>Enable SPDY/4</i> (Chrome's name for HTTP/2)</li>
	</ul>
	<p>See code & instructions for connecting at <a href="https://github.com/golang/net/tree/master/http2">https://github.com/golang/net/tree/master/http2</a>.</p>

	</body></html>`)
	}

	func home(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
	http.NotFound(w, r)
	return
	}
	io.WriteString(w, `<html>
	<body>
	<h1>Go + HTTP/2</h1>

	<p>Welcome to <a href="https://golang.org/">the Go language</a>'s <a
	href="https://http2.github.io/">HTTP/2</a> demo & interop server.</p>

	<p>Congratulations, <b>you're using HTTP/2 right now</b>.</p>

	<p>This server exists for others in the HTTP/2 community to test their HTTP/2 client implementations and point out flaws in our server.</p>

	<p>
	The code is at <a href="https://golang.org/x/net/http2">golang.org/x/net/http2</a> and
	is used transparently by the Go standard library from Go 1.6 and later.
	</p>

	<p>Contact info: <i>bradfitz@golang.org</i>, or <a
	href="https://golang.org/s/http2bug">file a bug</a>.</p>

	<h2>Handlers for testing</h2>
	<ul>
	<li>GET <a href="/reqinfo">/reqinfo</a> to dump the request + headers received</li>
	<li>GET <a href="/clockstream">/clockstream</a> streams the current time every second</li>
	<li>GET <a href="/gophertiles">/gophertiles</a> to see a page with a bunch of images</li>
	<li>GET <a href="/serverpush">/serverpush</a> to see a page with server push</li>
	<li>GET <a href="/file/gopher.png">/file/gopher.png</a> for a small file (does If-Modified-Since, Content-Range, etc)</li>
	<li>GET <a href="/file/go.src.tar.gz">/file/go.src.tar.gz</a> for a larger file (~10 MB)</li>
	<li>GET <a href="/redirect">/redirect</a> to redirect back to / (this page)</li>
	<li>GET <a href="/goroutines">/goroutines</a> to see all active goroutines in this server</li>
	<li>PUT something to <a href="/crc32">/crc32</a> to get a count of number of bytes and its CRC-32</li>
	<li>PUT something to <a href="/ECHO">/ECHO</a> and it will be streamed back to you capitalized</li>
	</ul>

	</body></html>`)
	}

	func reqInfoHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/plain")
	fmt.Fprintf(w, "Method: %s\n", r.Method)
	fmt.Fprintf(w, "Protocol: %s\n", r.Proto)
	fmt.Fprintf(w, "Host: %s\n", r.Host)
	fmt.Fprintf(w, "RemoteAddr: %s\n", r.RemoteAddr)
	fmt.Fprintf(w, "RequestURI: %q\n", r.RequestURI)
	fmt.Fprintf(w, "URL: %#v\n", r.URL)
	fmt.Fprintf(w, "Body.ContentLength: %d (-1 means unknown)\n", r.ContentLength)
	fmt.Fprintf(w, "Close: %v (relevant for HTTP/1 only)\n", r.Close)
	fmt.Fprintf(w, "TLS: %#v\n", r.TLS)
	fmt.Fprintf(w, "\nHeaders:\n")
	r.Header.Write(w)
	}

	func crcHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != "PUT" {
	http.Error(w, "PUT required.", 400)
	return
	}
	crc := crc32.NewIEEE()
	n, err := io.Copy(crc, r.Body)
	if err == nil {
	w.Header().Set("Content-Type", "text/plain")
	fmt.Fprintf(w, "bytes=%d, CRC32=%x", n, crc.Sum(nil))
	}
	}

	type capitalizeReader struct {
	r io.Reader
	}

	func (cr capitalizeReader) Read(p []byte) (n int, err error) {
	n, err = cr.r.Read(p)
	for i, b := range p[:n] {
	if b >= 'a' && b <= 'z' {
	p[i] = b - ('a' - 'A')
	}
	}
	return
	}

	type flushWriter struct {
	w io.Writer
	}

	func (fw flushWriter) Write(p []byte) (n int, err error) {
	n, err = fw.w.Write(p)
	if f, ok := fw.w.(http.Flusher); ok {
	f.Flush()
	}
	return
	}

	func echoCapitalHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != "PUT" {
	http.Error(w, "PUT required.", 400)
	return
	}
	io.Copy(flushWriter{w}, capitalizeReader{r.Body})
	}

	var (
	fsGrp singleflight.Group
	fsMu sync.Mutex // guards fsCache
	fsCache = map[string]http.Handler{}
	)

	// fileServer returns a file-serving handler that proxies URL.
	// It lazily fetches URL on the first access and caches its contents forever.
	func fileServer(url string, latency time.Duration) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
	if latency > 0 {
	time.Sleep(latency)
	}
	hi, err := fsGrp.Do(url, func() (interface{}, error) {
	fsMu.Lock()
	if h, ok := fsCache[url]; ok {
	fsMu.Unlock()
	return h, nil
	}
	fsMu.Unlock()

	res, err := http.Get(url)
	if err != nil {
	return nil, err
	}
	defer res.Body.Close()
	slurp, err := ioutil.ReadAll(res.Body)
	if err != nil {
	return nil, err
	}

	modTime := time.Now()
	var h http.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
	http.ServeContent(w, r, path.Base(url), modTime, bytes.NewReader(slurp))
	})
	fsMu.Lock()
	fsCache[url] = h
	fsMu.Unlock()
	return h, nil
	})
	if err != nil {
	http.Error(w, err.Error(), 500)
	return
	}
	hi.(http.Handler).ServeHTTP(w, r)
	})
	}

	func clockStreamHandler(w http.ResponseWriter, r *http.Request) {
	clientGone := w.(http.CloseNotifier).CloseNotify()
	w.Header().Set("Content-Type", "text/plain")
	ticker := time.NewTicker(1 * time.Second)
	defer ticker.Stop()
	fmt.Fprintf(w, "# ~1KB of junk to force browsers to start rendering immediately: \n")
	io.WriteString(w, strings.Repeat("# xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\n", 13))

	for {
	fmt.Fprintf(w, "%v\n", time.Now())
	w.(http.Flusher).Flush()
	select {
	case <-ticker.C:
	case <-clientGone:
	log.Printf("Client %v disconnected from the clock", r.RemoteAddr)
	return
	}
	}
	}

	func registerHandlers() {
	tiles := newGopherTilesHandler()
	push := newPushHandler()

	mux2 := http.NewServeMux()
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
	switch {
	case r.URL.Path == "/gophertiles":
	tiles.ServeHTTP(w, r) // allow HTTP/2 + HTTP/1.x
	return
	case strings.HasPrefix(r.URL.Path, "/serverpush"):
	push.ServeHTTP(w, r) // allow HTTP/2 + HTTP/1.x
	return
	case r.TLS == nil: // do not allow HTTP/1.x for anything else
	http.Redirect(w, r, "https://"+httpsHost()+"/", http.StatusFound)
	return
	}
	if r.ProtoMajor == 1 {
	if r.URL.Path == "/reqinfo" {
	reqInfoHandler(w, r)
	return
	}
	homeOldHTTP(w, r)
	return
	}
	mux2.ServeHTTP(w, r)
	})
	mux2.HandleFunc("/", home)
	mux2.Handle("/file/gopher.png", fileServer("https://golang.org/doc/gopher/frontpage.png", 0))
	mux2.Handle("/file/go.src.tar.gz", fileServer("https://storage.googleapis.com/golang/go1.4.1.src.tar.gz", 0))
	mux2.HandleFunc("/reqinfo", reqInfoHandler)
	mux2.HandleFunc("/crc32", crcHandler)
	mux2.HandleFunc("/ECHO", echoCapitalHandler)
	mux2.HandleFunc("/clockstream", clockStreamHandler)
	mux2.Handle("/gophertiles", tiles)
	mux2.HandleFunc("/redirect", func(w http.ResponseWriter, r *http.Request) {
	http.Redirect(w, r, "/", http.StatusFound)
	})
	stripHomedir := regexp.MustCompile(`/(Users\|home)/\w+`)
	mux2.HandleFunc("/goroutines", func(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	buf := make([]byte, 2<<20)
	w.Write(stripHomedir.ReplaceAll(buf[:runtime.Stack(buf, true)], nil))
	})
	}

	var pushResources = map[string]http.Handler{
	"/serverpush/static/jquery.min.js": fileServer("https://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js", 100*time.Millisecond),
	"/serverpush/static/godocs.js": fileServer("https://golang.org/lib/godoc/godocs.js", 100*time.Millisecond),
	"/serverpush/static/playground.js": fileServer("https://golang.org/lib/godoc/playground.js", 100*time.Millisecond),
	"/serverpush/static/style.css": fileServer("https://golang.org/lib/godoc/style.css", 100*time.Millisecond),
	}

	func newPushHandler() http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
	for path, handler := range pushResources {
	if r.URL.Path == path {
	handler.ServeHTTP(w, r)
	return
	}
	}

	cacheBust := time.Now().UnixNano()
	if pusher, ok := w.(http.Pusher); ok {
	for path := range pushResources {
	url := fmt.Sprintf("%s?%d", path, cacheBust)
	if err := pusher.Push(url, nil); err != nil {
	log.Printf("Failed to push %v: %v", path, err)
	}
	}
	}
	time.Sleep(100 * time.Millisecond) // fake network latency + parsing time
	if err := pushTmpl.Execute(w, struct {
	CacheBust int64
	HTTPSHost string
	HTTPHost string
	}{
	CacheBust: cacheBust,
	HTTPSHost: httpsHost(),
	HTTPHost: httpHost(),
	}); err != nil {
	log.Printf("Executing server push template: %v", err)
	}
	})
	}

	func newGopherTilesHandler() http.Handler {
	const gopherURL = "https://blog.golang.org/go-programming-language-turns-two_gophers.jpg"
	res, err := http.Get(gopherURL)
	if err != nil {
	log.Fatal(err)
	}
	if res.StatusCode != 200 {
	log.Fatalf("Error fetching %s: %v", gopherURL, res.Status)
	}
	slurp, err := ioutil.ReadAll(res.Body)
	res.Body.Close()
	if err != nil {
	log.Fatal(err)
	}
	im, err := jpeg.Decode(bytes.NewReader(slurp))
	if err != nil {
	if len(slurp) > 1024 {
	slurp = slurp[:1024]
	}
	log.Fatalf("Failed to decode gopher image: %v (got %q)", err, slurp)
	}

	type subImager interface {
	SubImage(image.Rectangle) image.Image
	}
	const tileSize = 32
	xt := im.Bounds().Max.X / tileSize
	yt := im.Bounds().Max.Y / tileSize
	var tile [][][]byte // y -> x -> jpeg bytes
	for yi := 0; yi < yt; yi++ {
	var row [][]byte
	for xi := 0; xi < xt; xi++ {
	si := im.(subImager).SubImage(image.Rectangle{
	Min: image.Point{xi * tileSize, yi * tileSize},
	Max: image.Point{(xi + 1) * tileSize, (yi + 1) * tileSize},
	})
	buf := new(bytes.Buffer)
	if err := jpeg.Encode(buf, si, &jpeg.Options{Quality: 90}); err != nil {
	log.Fatal(err)
	}
	row = append(row, buf.Bytes())
	}
	tile = append(tile, row)
	}
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
	ms, _ := strconv.Atoi(r.FormValue("latency"))
	const nanosPerMilli = 1e6
	if r.FormValue("x") != "" {
	x, _ := strconv.Atoi(r.FormValue("x"))
	y, _ := strconv.Atoi(r.FormValue("y"))
	if ms <= 1000 {
	time.Sleep(time.Duration(ms) * nanosPerMilli)
	}
	if x >= 0 && x < xt && y >= 0 && y < yt {
	http.ServeContent(w, r, "", time.Time{}, bytes.NewReader(tile[y][x]))
	return
	}
	}
	io.WriteString(w, "<html><body onload='showtimes()'>")
	fmt.Fprintf(w, "A grid of %d tiled images is below. Compare:<p>", xt*yt)
	for _, ms := range []int{0, 30, 200, 1000} {
	d := time.Duration(ms) * nanosPerMilli
	fmt.Fprintf(w, "[<a href='https://%s/gophertiles?latency=%d'>HTTP/2, %v latency</a>] [<a href='http://%s/gophertiles?latency=%d'>HTTP/1, %v latency</a>]<br>\n",
	httpsHost(), ms, d,
	httpHost(), ms, d,
	)
	}
	io.WriteString(w, "<p>\n")
	cacheBust := time.Now().UnixNano()
	for y := 0; y < yt; y++ {
	for x := 0; x < xt; x++ {
	fmt.Fprintf(w, "<img width=%d height=%d src='/gophertiles?x=%d&y=%d&cachebust=%d&latency=%d'>",
	tileSize, tileSize, x, y, cacheBust, ms)
	}
	io.WriteString(w, "<br/>\n")
	}
	io.WriteString(w, `<p><div id='loadtimes'></div></p>
	<script>
	function showtimes() {
	var times = 'Times from connection start:<br>'
	times += 'DOM loaded: ' + (window.performance.timing.domContentLoadedEventEnd - window.performance.timing.connectStart) + 'ms<br>'
	times += 'DOM complete (images loaded): ' + (window.performance.timing.domComplete - window.performance.timing.connectStart) + 'ms<br>'
	document.getElementById('loadtimes').innerHTML = times
	}
	</script>
	<hr><a href='/'><&lt Back to Go HTTP/2 demo server</a></body></html>`)
	})
	}

	func httpsHost() string {
	if *hostHTTPS != "" {
	return *hostHTTPS
	}
	if v := *httpsAddr; strings.HasPrefix(v, ":") {
	return "localhost" + v
	} else {
	return v
	}
	}

	func httpHost() string {
	if *hostHTTP != "" {
	return *hostHTTP
	}
	if v := *httpAddr; strings.HasPrefix(v, ":") {
	return "localhost" + v
	} else {
	return v
	}
	}

	func serveProdTLS() error {
	const cacheDir = "/var/cache/autocert"
	if err := os.MkdirAll(cacheDir, 0700); err != nil {
	return err
	}
	m := autocert.Manager{
	Cache: autocert.DirCache(cacheDir),
	Prompt: autocert.AcceptTOS,
	HostPolicy: autocert.HostWhitelist("http2.golang.org"),
	}
	srv := &http.Server{
	TLSConfig: &tls.Config{
	GetCertificate: m.GetCertificate,
	},
	}
	http2.ConfigureServer(srv, &http2.Server{
	NewWriteScheduler: func() http2.WriteScheduler {
	return http2.NewPriorityWriteScheduler(nil)
	},
	})
	ln, err := net.Listen("tcp", ":443")
	if err != nil {
	return err
	}
	return srv.Serve(tls.NewListener(tcpKeepAliveListener{ln.(*net.TCPListener)}, srv.TLSConfig))
	}

	type tcpKeepAliveListener struct {
	*net.TCPListener
	}

	func (ln tcpKeepAliveListener) Accept() (c net.Conn, err error) {
	tc, err := ln.AcceptTCP()
	if err != nil {
	return
	}
	tc.SetKeepAlive(true)
	tc.SetKeepAlivePeriod(3 * time.Minute)
	return tc, nil
	}

	func serveProd() error {
	errc := make(chan error, 2)
	go func() { errc <- http.ListenAndServe(":80", nil) }()
	go func() { errc <- serveProdTLS() }()
	return <-errc
	}

	const idleTimeout = 5 * time.Minute
	const activeTimeout = 10 * time.Minute

	// TODO: put this into the standard library and actually send
	// PING frames and GOAWAY, etc: golang.org/issue/14204
	func idleTimeoutHook() func(net.Conn, http.ConnState) {
	var mu sync.Mutex
	m := map[net.Conn]*time.Timer{}
	return func(c net.Conn, cs http.ConnState) {
	mu.Lock()
	defer mu.Unlock()
	if t, ok := m[c]; ok {
	delete(m, c)
	t.Stop()
	}
	var d time.Duration
	switch cs {
	case http.StateNew, http.StateIdle:
	d = idleTimeout
	case http.StateActive:
	d = activeTimeout
	default:
	return
	}
	m[c] = time.AfterFunc(d, func() {
	log.Printf("closing idle conn %v after %v", c.RemoteAddr(), d)
	go c.Close()
	})
	}
	}

	func main() {
	var srv http.Server
	flag.BoolVar(&http2.VerboseLogs, "verbose", false, "Verbose HTTP/2 debugging.")
	flag.Parse()
	srv.Addr = *httpsAddr
	srv.ConnState = idleTimeoutHook()

	registerHandlers()

	if *prod {
	*hostHTTP = "http2.golang.org"
	*hostHTTPS = "http2.golang.org"
	log.Fatal(serveProd())
	}

	url := "https://" + httpsHost() + "/"
	log.Printf("Listening on " + url)
	http2.ConfigureServer(&srv, &http2.Server{})

	if *httpAddr != "" {
	go func() {
	log.Printf("Listening on http://" + httpHost() + "/ (for unencrypted HTTP/1)")
	log.Fatal(http.ListenAndServe(*httpAddr, nil))
	}()
	}

	go func() {
	log.Fatal(srv.ListenAndServeTLS("server.crt", "server.key"))
	}()
	select {}
	}