//
// WRP - Web Rendering Proxy
//
// Copyright (c) 2013-2018 Antoni Sawicki
// Copyright (c) 2019-2022 Google LLC
//
package main
import (
"bytes"
"context"
"embed"
"flag"
"fmt"
"html/template"
"image"
"image/color/palette"
"image/gif"
"image/png"
"io/ioutil"
"log"
"math"
"math/rand"
"net/http"
"net/url"
"os"
"os/signal"
"strconv"
"strings"
"syscall"
"time"
"github.com/MaxHalford/halfgone"
"github.com/chromedp/cdproto/css"
"github.com/chromedp/cdproto/emulation"
"github.com/chromedp/cdproto/page"
"github.com/chromedp/chromedp"
"github.com/soniakeys/quant/median"
)
var (
version = "4.5.3"
srv http.Server
ctx context.Context
cancel context.CancelFunc
img = make(map[string]bytes.Buffer)
ismap = make(map[string]wrpReq)
noDel bool
defType string
defGeom geom
htmlTmpl *template.Template
)
// go:embed *.html
var fs embed.FS
type geom struct {
w int64
h int64
c int64
}
// Data for html template
type uiData struct {
Version string
URL string
BgColor string
NColors int64
Width int64
Height int64
Zoom float64
ImgType string
ImgURL string
ImgSize string
ImgWidth int
ImgHeight int
MapURL string
PageHeight string
}
// Parameters for HTML print function
type printParams struct {
bgColor string
pageHeight string
imgSize string
imgURL string
mapURL string
imgWidth int
imgHeight int
}
// WRP Request
type wrpReq struct {
url string // url
width int64 // width
height int64 // height
zoom float64 // zoom/scale
colors int64 // #colors
mouseX int64 // mouseX
mouseY int64 // mouseY
keys string // keys to send
buttons string // Fn buttons
imgType string // imgtype
w http.ResponseWriter
r *http.Request
}
// Parse HTML Form, Process Input Boxes, Etc.
func (rq *wrpReq) parseForm() {
rq.r.ParseForm()
rq.url = rq.r.FormValue("url")
if len(rq.url) > 1 && !strings.HasPrefix(rq.url, "http") {
rq.url = fmt.Sprintf("http://www.google.com/search?q=%s", url.QueryEscape(rq.url))
}
rq.width, _ = strconv.ParseInt(rq.r.FormValue("w"), 10, 64)
rq.height, _ = strconv.ParseInt(rq.r.FormValue("h"), 10, 64)
if rq.width < 10 && rq.height < 10 {
rq.width = defGeom.w
rq.height = defGeom.h
}
rq.zoom, _ = strconv.ParseFloat(rq.r.FormValue("z"), 64)
if rq.zoom < 0.1 {
rq.zoom = 1.0
}
rq.colors, _ = strconv.ParseInt(rq.r.FormValue("c"), 10, 64)
if rq.colors < 2 || rq.colors > 256 {
rq.colors = defGeom.c
}
rq.keys = rq.r.FormValue("k")
rq.buttons = rq.r.FormValue("Fn")
rq.imgType = rq.r.FormValue("t")
if rq.imgType != "gif" && rq.imgType != "png" {
rq.imgType = defType
}
log.Printf("%s WrpReq from UI Form: %+v\n", rq.r.RemoteAddr, rq)
}
// Display WP UI
func (rq *wrpReq) printHTML(p printParams) {
rq.w.Header().Set("Cache-Control", "max-age=0")
rq.w.Header().Set("Expires", "-1")
rq.w.Header().Set("Pragma", "no-cache")
rq.w.Header().Set("Content-Type", "text/html")
data := uiData{
Version: version,
URL: rq.url,
BgColor: p.bgColor,
Width: rq.width,
Height: rq.height,
NColors: rq.colors,
Zoom: rq.zoom,
ImgType: rq.imgType,
ImgSize: p.imgSize,
ImgWidth: p.imgWidth,
ImgHeight: p.imgHeight,
ImgURL: p.imgURL,
MapURL: p.mapURL,
PageHeight: p.pageHeight,
}
err := htmlTmpl.Execute(rq.w, data)
if err != nil {
log.Fatal(err)
}
}
// Determine what action to take
func (rq *wrpReq) action() chromedp.Action {
// Mouse Click
if rq.mouseX > 0 && rq.mouseY > 0 {
log.Printf("%s Mouse Click %d,%d\n", rq.r.RemoteAddr, rq.mouseX, rq.mouseY)
return chromedp.MouseClickXY(float64(rq.mouseX)/float64(rq.zoom), float64(rq.mouseY)/float64(rq.zoom))
}
// Buttons
if len(rq.buttons) > 0 {
log.Printf("%s Button %v\n", rq.r.RemoteAddr, rq.buttons)
switch rq.buttons {
case "Bk":
return chromedp.NavigateBack()
case "St":
return chromedp.Stop()
case "Re":
return chromedp.Reload()
case "Bs":
return chromedp.KeyEvent("\b")
case "Rt":
return chromedp.KeyEvent("\r")
case "<":
return chromedp.KeyEvent("\u0302")
case "^":
return chromedp.KeyEvent("\u0304")
case "v":
return chromedp.KeyEvent("\u0301")
case ">":
return chromedp.KeyEvent("\u0303")
}
}
// Keys
if len(rq.keys) > 0 {
log.Printf("%s Sending Keys: %#v\n", rq.r.RemoteAddr, rq.keys)
return chromedp.KeyEvent(rq.keys)
}
// Navigate to URL
log.Printf("%s Processing Capture Request for %s\n", rq.r.RemoteAddr, rq.url)
return chromedp.Navigate(rq.url)
}
// Process Keyboard and Mouse events or Navigate to the desired URL.
func (rq *wrpReq) navigate() {
err := chromedp.Run(ctx, rq.action())
if err != nil {
if err.Error() == "context canceled" {
log.Printf("%s Contex cancelled, try again", rq.r.RemoteAddr)
fmt.Fprintf(rq.w, "
%s
-- restarting, try again", err)
ctx, cancel = chromedp.NewContext(context.Background())
return
}
log.Printf("%s %s", rq.r.RemoteAddr, err)
fmt.Fprintf(rq.w, "
%s
", err)
}
}
// https://github.com/chromedp/chromedp/issues/979
func chromedpCaptureScreenshot(res *[]byte, h int64) chromedp.Action {
if res == nil {
panic("res cannot be nil")
}
if h == 0 {
return chromedp.CaptureScreenshot(res)
}
return chromedp.ActionFunc(func(ctx context.Context) error {
var err error
*res, err = page.CaptureScreenshot().Do(ctx)
return err
})
}
func gifPalette(i image.Image, n int64) image.Image {
switch n {
case 2:
i = halfgone.FloydSteinbergDitherer{}.Apply(halfgone.ImageToGray(i))
case 216:
var FastGifLut = [256]int{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5}
r := i.Bounds()
// NOTE: the color index computation below works only for palette.WebSafe!
p := image.NewPaletted(r, palette.WebSafe)
if i64, ok := i.(image.RGBA64Image); ok {
for y := r.Min.Y; y < r.Max.Y; y++ {
for x := r.Min.X; x < r.Max.X; x++ {
c := i64.RGBA64At(x, y)
r6 := FastGifLut[c.R>>8]
g6 := FastGifLut[c.G>>8]
b6 := FastGifLut[c.B>>8]
p.SetColorIndex(x, y, uint8(36*r6+6*g6+b6))
}
}
} else {
for y := r.Min.Y; y < r.Max.Y; y++ {
for x := r.Min.X; x < r.Max.X; x++ {
c := i.At(x, y)
r, g, b, _ := c.RGBA()
r6 := FastGifLut[r&0xff]
g6 := FastGifLut[g&0xff]
b6 := FastGifLut[b&0xff]
p.SetColorIndex(x, y, uint8(36*r6+6*g6+b6))
}
}
}
i = p
default:
q := median.Quantizer(n)
i = q.Paletted(i)
}
return i
}
// Capture currently rendered web page to an image and fake ISMAP
func (rq *wrpReq) capture() {
var err error
var styles []*css.ComputedStyleProperty
var r, g, b int
var h int64
var pngcap []byte
chromedp.Run(ctx,
emulation.SetDeviceMetricsOverride(int64(float64(rq.width)/rq.zoom), 10, rq.zoom, false),
chromedp.Location(&rq.url),
chromedp.ComputedStyle("body", &styles, chromedp.ByQuery),
chromedp.ActionFunc(func(ctx context.Context) error {
_, _, _, _, _, s, err := page.GetLayoutMetrics().Do(ctx)
if err == nil {
h = int64(math.Ceil(s.Height))
}
return nil
}),
)
for _, style := range styles {
if style.Name == "background-color" {
fmt.Sscanf(style.Value, "rgb(%d,%d,%d)", &r, &g, &b)
}
}
log.Printf("%s Landed on: %s, Height: %v\n", rq.r.RemoteAddr, rq.url, h)
height := int64(float64(rq.height) / rq.zoom)
if rq.height == 0 && h > 0 {
height = h + 30
}
chromedp.Run(
ctx, emulation.SetDeviceMetricsOverride(int64(float64(rq.width)/rq.zoom), height, rq.zoom, false),
chromedp.Sleep(time.Second*2), // TODO(tenox): totally lame, find a better way to determine if page is rendered
)
// Capture screenshot...
err = chromedp.Run(ctx, chromedpCaptureScreenshot(&pngcap, rq.height))
if err != nil {
if err.Error() == "context canceled" {
log.Printf("%s Contex cancelled, try again", rq.r.RemoteAddr)
fmt.Fprintf(rq.w, "
%s
-- restarting, try again", err)
ctx, cancel = chromedp.NewContext(context.Background())
return
}
log.Printf("%s Failed to capture screenshot: %s\n", rq.r.RemoteAddr, err)
fmt.Fprintf(rq.w, "
Unable to capture screenshot:
%s
\n", err)
return
}
seq := rand.Intn(9999)
imgpath := fmt.Sprintf("/img/%04d.%s", seq, rq.imgType)
mappath := fmt.Sprintf("/map/%04d.map", seq)
ismap[mappath] = *rq
var ssize string
var iw, ih int
switch rq.imgType {
case "gif":
i, err := png.Decode(bytes.NewReader(pngcap))
if err != nil {
log.Printf("%s Failed to decode PNG screenshot: %s\n", rq.r.RemoteAddr, err)
fmt.Fprintf(rq.w, "
Unable to decode page PNG screenshot:
%s
\n", err)
return
}
st := time.Now()
var gifbuf bytes.Buffer
err = gif.Encode(&gifbuf, gifPalette(i, rq.colors), &gif.Options{})
if err != nil {
log.Printf("%s Failed to encode GIF: %s\n", rq.r.RemoteAddr, err)
fmt.Fprintf(rq.w, "
Unable to encode GIF:
%s
\n", err)
return
}
img[imgpath] = gifbuf
ssize = fmt.Sprintf("%.0f KB", float32(len(gifbuf.Bytes()))/1024.0)
iw = i.Bounds().Max.X
ih = i.Bounds().Max.Y
log.Printf("%s Encoded GIF image: %s, Size: %s, Colors: %d, Res: %dx%d, Time: %vms\n", rq.r.RemoteAddr, imgpath, ssize, rq.colors, iw, ih, time.Since(st).Milliseconds())
case "png":
pngbuf := bytes.NewBuffer(pngcap)
img[imgpath] = *pngbuf
cfg, _, _ := image.DecodeConfig(pngbuf)
ssize = fmt.Sprintf("%.0f KB", float32(len(pngbuf.Bytes()))/1024.0)
iw = cfg.Width
ih = cfg.Height
log.Printf("%s Got PNG image: %s, Size: %s, Res: %dx%d\n", rq.r.RemoteAddr, imgpath, ssize, iw, ih)
}
rq.printHTML(printParams{
bgColor: fmt.Sprintf("#%02X%02X%02X", r, g, b),
pageHeight: fmt.Sprintf("%d PX", h),
imgSize: ssize,
imgURL: imgpath,
mapURL: mappath,
imgWidth: iw,
imgHeight: ih,
})
log.Printf("%s Done with capture for %s\n", rq.r.RemoteAddr, rq.url)
}
// Process HTTP requests to WRP '/' url
func pageServer(w http.ResponseWriter, r *http.Request) {
log.Printf("%s Page Request for %s [%+v]\n", r.RemoteAddr, r.URL.Path, r.URL.RawQuery)
rq := wrpReq{
r: r,
w: w,
}
rq.parseForm()
if len(rq.url) < 4 {
rq.printHTML(printParams{bgColor: "#FFFFFF"})
return
}
rq.navigate()
rq.capture()
}
// Process HTTP requests to ISMAP '/map/' url
func mapServer(w http.ResponseWriter, r *http.Request) {
log.Printf("%s ISMAP Request for %s [%+v]\n", r.RemoteAddr, r.URL.Path, r.URL.RawQuery)
rq, ok := ismap[r.URL.Path]
rq.r = r
rq.w = w
if !ok {
fmt.Fprintf(w, "Unable to find map %s\n", r.URL.Path)
log.Printf("Unable to find map %s\n", r.URL.Path)
return
}
if !noDel {
defer delete(ismap, r.URL.Path)
}
n, err := fmt.Sscanf(r.URL.RawQuery, "%d,%d", &rq.mouseX, &rq.mouseY)
if err != nil || n != 2 {
fmt.Fprintf(w, "n=%d, err=%s\n", n, err)
log.Printf("%s ISMAP n=%d, err=%s\n", r.RemoteAddr, n, err)
return
}
log.Printf("%s WrpReq from ISMAP: %+v\n", r.RemoteAddr, rq)
if len(rq.url) < 4 {
rq.printHTML(printParams{bgColor: "#FFFFFF"})
return
}
rq.navigate()
rq.capture()
}
// Process HTTP requests for images '/img/' url
func imgServer(w http.ResponseWriter, r *http.Request) {
log.Printf("%s IMG Request for %s\n", r.RemoteAddr, r.URL.Path)
imgbuf, ok := img[r.URL.Path]
if !ok || imgbuf.Bytes() == nil {
fmt.Fprintf(w, "Unable to find image %s\n", r.URL.Path)
log.Printf("%s Unable to find image %s\n", r.RemoteAddr, r.URL.Path)
return
}
if !noDel {
defer delete(img, r.URL.Path)
}
switch {
case strings.HasPrefix(r.URL.Path, ".gif"):
w.Header().Set("Content-Type", "image/gif")
case strings.HasPrefix(r.URL.Path, ".png"):
w.Header().Set("Content-Type", "image/png")
}
w.Header().Set("Content-Length", strconv.Itoa(len(imgbuf.Bytes())))
w.Header().Set("Cache-Control", "max-age=0")
w.Header().Set("Expires", "-1")
w.Header().Set("Pragma", "no-cache")
w.Write(imgbuf.Bytes())
w.(http.Flusher).Flush()
}
// Process HTTP requests for Shutdown via '/shutdown/' url
func haltServer(w http.ResponseWriter, r *http.Request) {
log.Printf("%s Shutdown Request for %s\n", r.RemoteAddr, r.URL.Path)
w.Header().Set("Cache-Control", "max-age=0")
w.Header().Set("Expires", "-1")
w.Header().Set("Pragma", "no-cache")
w.Header().Set("Content-Type", "text/plain")
fmt.Fprintf(w, "Shutting down WRP...\n")
w.(http.Flusher).Flush()
time.Sleep(time.Second * 2)
cancel()
srv.Shutdown(context.Background())
os.Exit(1)
}
// returns html template, either from html file or built-in
func tmpl(t string) string {
var tmpl []byte
fh, err := os.Open(t)
if err != nil {
goto builtin
}
tmpl, err = ioutil.ReadAll(fh)
if err != nil {
goto builtin
}
log.Printf("Got UI template from %v file\n", t)
return string(tmpl)
builtin:
fhs, err := fs.Open("/wrp.html")
if err != nil {
log.Fatal(err)
}
tmpl, err = ioutil.ReadAll(fhs)
if err != nil {
log.Fatal(err)
}
log.Printf("Got UI template from built-in\n")
return string(tmpl)
}
// Main...
func main() {
var addr, fgeom, tHTML string
var headless bool
var debug bool
var err error
flag.StringVar(&addr, "l", ":8080", "Listen address:port, default :8080")
flag.BoolVar(&headless, "h", true, "Headless mode - hide browser window")
flag.BoolVar(&debug, "d", false, "Debug ChromeDP")
flag.BoolVar(&noDel, "n", false, "Do not free maps and images after use")
flag.StringVar(&defType, "t", "gif", "Image type: gif|png")
flag.StringVar(&fgeom, "g", "1152x600x216", "Geometry: width x height x colors, height can be 0 for unlimited")
flag.StringVar(&tHTML, "ui", "wrp.html", "HTML template file for the UI")
flag.Parse()
if len(os.Getenv("PORT")) > 0 {
addr = ":" + os.Getenv(("PORT"))
}
n, err := fmt.Sscanf(fgeom, "%dx%dx%d", &defGeom.w, &defGeom.h, &defGeom.c)
if err != nil || n != 3 {
log.Fatalf("Unable to parse -g geometry flag / %s", err)
}
opts := append(chromedp.DefaultExecAllocatorOptions[:],
chromedp.Flag("headless", headless),
chromedp.Flag("hide-scrollbars", false),
)
actx, acancel := chromedp.NewExecAllocator(context.Background(), opts...)
defer acancel()
switch debug {
case true:
ctx, cancel = chromedp.NewContext(actx, chromedp.WithDebugf(log.Printf))
default:
ctx, cancel = chromedp.NewContext(actx)
}
defer cancel()
rand.Seed(time.Now().UnixNano())
c := make(chan os.Signal)
signal.Notify(c, os.Interrupt, syscall.SIGTERM)
go func() {
<-c
log.Printf("Interrupt - shutting down.")
cancel()
srv.Shutdown(context.Background())
os.Exit(1)
}()
http.HandleFunc("/", pageServer)
http.HandleFunc("/map/", mapServer)
http.HandleFunc("/img/", imgServer)
http.HandleFunc("/shutdown/", haltServer)
http.HandleFunc("/favicon.ico", http.NotFound)
log.Printf("Web Rendering Proxy Version %s\n", version)
log.Printf("Args: %q", os.Args)
log.Printf("Default Img Type: %v, Geometry: %+v", defType, defGeom)
htmlTmpl, err = template.New("wrp.html").Parse(tmpl(tHTML))
if err != nil {
log.Fatal(err)
}
log.Printf("Starting WRP http server on %s\n", addr)
srv.Addr = addr
err = srv.ListenAndServe()
if err != nil {
log.Fatal(err)
}
}