//
// WRP - Web Rendering Proxy
//
// Copyright (c) 2013-2018 Antoni Sawicki
// Copyright (c) 2019 Google LLC
//
package main
import (
"bytes"
"context"
"flag"
"fmt"
"image/gif"
"image/png"
"log"
"math/rand"
"net/http"
"net/url"
"strconv"
"strings"
"time"
"encoding/json"
"encoding/base64"
"net"
"github.com/chromedp/cdproto/emulation"
"github.com/chromedp/cdproto/runtime"
"github.com/chromedp/cdproto/cdp"
"github.com/chromedp/chromedp"
"github.com/ericpauley/go-quantize/quantize"
)
var (
version = "3.0"
srv http.Server
ctx context.Context
cancel context.CancelFunc
gifmap = make(map[string]bytes.Buffer)
)
// Params - Page Configuration Parameters
type Params struct {
U string // url
P int64 // page
W int64 // width
H int64 // height
S float64 // scale
C int64 // #colors
r string // remote addr
l string // local addr
}
func (p *Params) parseParams(req *http.Request) {
req.ParseForm()
p.r = string(req.RemoteAddr)
p.l = req.Context().Value(http.LocalAddrContextKey).(*net.TCPAddr).IP.String()
p.U = req.FormValue("url")
var x,y int64
fmt.Sscanf(req.URL.RawQuery, "%d,%d", &x, &y)
log.Printf("%s Page Request for %s url=\"%s\" [%+v]\n", req.RemoteAddr, req.URL.Path, p.U, req.URL.RawQuery)
if len(p.U) > 1 && !strings.HasPrefix(p.U, "http") {
p.U = fmt.Sprintf("http://www.google.com/search?q=%s", url.QueryEscape(p.U))
}
p.P, _ = strconv.ParseInt(req.FormValue("p"), 10, 64)
if req.FormValue("pg") == "Dn" {
p.P++
} else if req.FormValue("pg") == "Up" {
p.P--
} else {
p.P = 0
}
p.W, _ = strconv.ParseInt(req.FormValue("w"), 10, 64)
if p.P < 10 {
p.P = 1024
}
p.H, _ = strconv.ParseInt(req.FormValue("h"), 10, 64)
if p.H < 10 {
p.H = 768
}
p.S, _ = strconv.ParseFloat(req.FormValue("s"), 64)
if p.S < 0.1 {
p.S = 1.0
}
p.C, _ = strconv.ParseInt(req.FormValue("c"), 10, 64)
if p.C < 2 || p.C > 256 {
p.C = 256
}
m, _ := json.Marshal(*p)
log.Printf("DEBUG: Struct: %+v Json: %s Base64: %s\n", p, string(m), base64.StdEncoding.EncodeToString([]byte(m)))
}
func pageServer(out http.ResponseWriter, req *http.Request) {
var p Params
p.parseParams(req)
out.Header().Set("Content-Type", "text/html")
fmt.Fprintf(out, "\n", version)
fmt.Fprintf(out, "\nWRP %s\n\n", p.U)
fmt.Fprintf(out, "
\n")
fmt.Fprintf(out, "\nWeb Rendering Proxy Version %s | Shutdown WRP\n\n", p.W, p.H, p.S, p.C, version)
}
func imgServer(out http.ResponseWriter, req *http.Request) {
log.Printf("%s IMG Request for %s\n", req.RemoteAddr, req.URL.Path)
gifbuf, ok := gifmap[req.URL.Path]
if !ok || gifbuf.Bytes() == nil {
fmt.Fprintf(out, "Unable to find image %s\n", req.URL.Path)
log.Printf("Unable to find image %s\n", req.URL.Path)
return
}
defer delete(gifmap, req.URL.Path)
out.Header().Set("Content-Type", "image/gif")
out.Header().Set("Content-Length", strconv.Itoa(len(gifbuf.Bytes())))
out.Write(gifbuf.Bytes())
out.(http.Flusher).Flush()
}
func (p Params) capture(c string, out http.ResponseWriter) {
var nodes []*cdp.Node
var pngbuf []byte
var gifbuf bytes.Buffer
var loc string
var res *runtime.RemoteObject
log.Printf("%s Processing Capture Request for %s\n", c, p.U)
// Run ChromeDP Magic
err := chromedp.Run(ctx,
emulation.SetDeviceMetricsOverride(int64(float64(p.W)/p.S), int64(float64(p.H)/p.S), p.S, false),
chromedp.Navigate(p.U),
chromedp.Evaluate(fmt.Sprintf("window.scrollTo(0, %d);", p.P*int64(float64(p.H)*float64(0.9))), &res),
chromedp.Sleep(time.Second*1),
chromedp.Location(&loc))
if err != nil {
if err.Error() == "context canceled" {
log.Printf("%s Contex cancelled, try again", c)
fmt.Fprintf(out, "
%s
-- restarting, try again", err)
ctx, cancel = chromedp.NewContext(context.Background())
} else {
log.Printf("%s %s", c, err)
fmt.Fprintf(out, "
%s
", err)
}
return
}
log.Printf("%s Landed on: %s, Nodes: %d\n", c, loc, len(nodes))
// Process Screenshot Image
err = chromedp.Run(ctx, chromedp.CaptureScreenshot(&pngbuf))
if err != nil {
log.Printf("%s Failed to capture screenshot: %s\n", c, err)
fmt.Fprintf(out, "
Unable to capture screenshot:
%s
\n", err)
return
}
bytes.NewReader(pngbuf).Seek(0, 0)
img, err := png.Decode(bytes.NewReader(pngbuf))
if err != nil {
log.Printf("%s Failed to decode screenshot: %s\n", c, err)
fmt.Fprintf(out, "
Unable to decode page screenshot:
%s
\n", err)
return
}
gifbuf.Reset()
err = gif.Encode(&gifbuf, img, &gif.Options{NumColors: int(p.C), Quantizer: quantize.MedianCutQuantizer{}})
if err != nil {
log.Printf("%s Failed to encode GIF: %s\n", c, err)
fmt.Fprintf(out, "
Unable to encode GIF:
%s
\n", err)
return
}
imgpath := fmt.Sprintf("/img/%04d.gif", rand.Intn(9999))
log.Printf("%s Encoded GIF image: %s, Size: %dKB, Colors: %d\n", c, imgpath, len(gifbuf.Bytes())/1024, p.C)
gifmap[imgpath] = gifbuf
// Gif location
fmt.Fprintf(out, "![\"wrp\"](\"%s\")
", loc, imgpath)
out.(http.Flusher).Flush()
log.Printf("%s Done with caputure for %s\n", c, p.U)
}
func haltServer(out http.ResponseWriter, req *http.Request) {
log.Printf("%s Shutdown Request for %s\n", req.RemoteAddr, req.URL.Path)
defer cancel()
srv.Shutdown(context.Background())
}
func main() {
var addr string
var head, headless bool
var debug bool
flag.StringVar(&addr, "l", ":8080", "Listen address:port, default :8080")
flag.BoolVar(&head, "h", false, "Headed mode - display browser window")
flag.BoolVar(&debug, "d", false, "Debug ChromeDP")
flag.Parse()
if head {
headless = false
} else {
headless = true
}
opts := append(chromedp.DefaultExecAllocatorOptions[:],
chromedp.Flag("headless", headless),
)
actx, cancel := chromedp.NewExecAllocator(context.Background(), opts...)
defer cancel()
if debug {
ctx, cancel = chromedp.NewContext(actx, chromedp.WithDebugf(log.Printf))
} else {
ctx, cancel = chromedp.NewContext(actx)
}
defer cancel()
rand.Seed(time.Now().UnixNano())
http.HandleFunc("/", pageServer)
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("Starting WRP http server on %s\n", addr)
srv.Addr = addr
err := srv.ListenAndServe()
if err != nil {
log.Fatal(err)
}
}