import project

main.go

@@ -0,0 +1,228 @@
+/*
+ *    Copyright (c) 2018 Unrud<unrud@outlook.com>
+ *
+ *    This file is part of Remote-Touchpad.
+ *
+ *    Foobar is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    Remote-Touchpad is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with Foobar.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package main
+
+import (
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"errors"
+	"flag"
+	"fmt"
+	"golang.org/x/net/websocket"
+	"log"
+	mathrand "math/rand"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const (
+	defaultSecretLength     int           = 8
+	authenticationRateLimit time.Duration = time.Second / 10
+	authenticationRateBurst int           = 10
+	challengeLength         int           = 8
+	defaultBind             string        = ":0"
+	version                 string        = "0.0.1"
+)
+
+func processCommand(plugin Plugin, command string) error {
+	commandParts := strings.Split(command, " ")
+	if commandParts[0] == "KeyboardText" {
+		text := strings.Join(commandParts[1:], " ")
+		return plugin.KeyboardText(text)
+	}
+	if len(commandParts) != 3 {
+		return errors.New("wrong number of arguments")
+	}
+	x, err := strconv.ParseInt(commandParts[1], 10, 32)
+	if err != nil {
+		return err
+	}
+	y, err := strconv.ParseInt(commandParts[2], 10, 32)
+	if err != nil {
+		return err
+	}
+	if commandParts[0] == "PointerMove" {
+		return plugin.PointerMove(int(x), int(y))
+	}
+	if commandParts[0] == "PointerScroll" {
+		return plugin.PointerScroll(int(x), int(y))
+	}
+	if commandParts[0] == "PointerButton" {
+		if x <= 0 || x > 3 {
+			return errors.New("unknown pointer button")
+		}
+		b := true
+		if y == 0 {
+			b = false
+		}
+		return plugin.PointerButton(uint(x), b)
+	}
+	return errors.New("unknown command")
+}
+
+type challenge struct {
+	message, expectedResponse string
+}
+
+func (c challenge) verify(response string) bool {
+	return c.expectedResponse == response
+}
+
+func authenticationChallengeGenerator(secret string, challenges chan<- challenge) {
+	unsecureSource := mathrand.NewSource(time.Now().UnixNano())
+	unsecureRand := mathrand.New(unsecureSource)
+	b := make([]byte, challengeLength)
+	for {
+		if _, err := unsecureRand.Read(b[:]); err != nil {
+			log.Fatal(err)
+		}
+		message := base64.StdEncoding.EncodeToString(b[:])
+		mac := hmac.New(sha256.New, []byte(message))
+		mac.Write([]byte(secret))
+		challenges <- challenge{
+			message:          message,
+			expectedResponse: base64.StdEncoding.EncodeToString(mac.Sum(nil)),
+		}
+		time.Sleep(authenticationRateLimit)
+	}
+}
+
+func secureRandBase64(length int) string {
+	b := make([]byte, length)
+	if _, err := rand.Read(b[:]); err != nil {
+		log.Fatal(err)
+	}
+	return base64.StdEncoding.EncodeToString(b[:])
+}
+
+func main() {
+	var bind, certFile, keyFile, secret string
+	var showVersion, invert bool
+	flag.BoolVar(&showVersion, "version", false, "show program's version number and exit")
+	flag.StringVar(&bind, "bind", defaultBind, "bind server to [IP]:PORT")
+	flag.StringVar(&secret, "secret", "", "shared secret for client authentication")
+	flag.StringVar(&certFile, "cert", "", "file containing TLS certificate")
+	flag.StringVar(&keyFile, "key", "", "file containing TLS private key")
+	flag.BoolVar(&invert, "invert", false, "use inverse colors for QR code")
+	flag.Parse()
+	if showVersion {
+		fmt.Println(version)
+		return
+	}
+	if certFile != "" && keyFile == "" {
+		log.Fatal("TLS certificate missing")
+	}
+	if certFile == "" && keyFile != "" {
+		log.Fatal("TLS private key missing")
+	}
+	tls := certFile != "" && keyFile != ""
+	if secret == "" {
+		secret = secureRandBase64(defaultSecretLength)
+	}
+	var plugin Plugin
+	platformErrors := ""
+	for _, f := range Plugins {
+		var err error
+		plugin, err = f()
+		if err == nil {
+			break
+		} else if _, ok := err.(UnsupportedPlatformError); ok {
+			platformErrors += err.Error() + "\n"
+		} else {
+			log.Fatal(err)
+		}
+	}
+	if plugin == nil {
+		log.Fatal("unsupported platform:\n" + platformErrors)
+	}
+	defer plugin.Close()
+	authenticationChallenges := make(chan challenge, authenticationRateBurst)
+	go authenticationChallengeGenerator(secret, authenticationChallenges)
+	listener, err := net.Listen("tcp", bind)
+	if err != nil {
+		log.Fatal(err)
+	}
+	addr := listener.Addr().(*net.TCPAddr)
+	host := ""
+	bindHost, _, err := net.SplitHostPort(bind)
+	if err != nil {
+		log.Fatal(err)
+	}
+	for _, b := range addr.IP {
+		if b != 0 {
+			host = bindHost
+			break
+		}
+	}
+	if host == "" {
+		host = FindDefaultHost()
+	}
+	port := addr.Port
+	mux := http.NewServeMux()
+	mux.Handle("/", http.FileServer(assetFS()))
+	mux.Handle("/ws", websocket.Handler(func(ws *websocket.Conn) {
+		var message string
+		challenge := <-authenticationChallenges
+		websocket.Message.Send(ws, challenge.message)
+		if err := websocket.Message.Receive(ws, &message); err != nil {
+			return
+		}
+		if !challenge.verify(message) {
+			return
+		}
+		for {
+			if err := websocket.Message.Receive(ws, &message); err != nil {
+				return
+			}
+			if err := processCommand(plugin, message); err != nil {
+				return
+			}
+		}
+	}))
+	domain := host
+	if port != 80 && !tls || port != 443 && tls {
+		domain = net.JoinHostPort(host, strconv.Itoa(port))
+	}
+	scheme := "http"
+	if tls {
+		scheme = "https"
+	}
+	url := fmt.Sprintf("%s://%s/#%s\n", scheme, domain, secret)
+	readyMsg := "ready: " + url
+	qrCode, _ := GenerateQRCode(url, invert)
+	readyMsg += qrCode
+	if !tls {
+		readyMsg += ("" +
+			"▌   WARNING: TLS is not enabled    ▐\n" +
+			"▌Don't use in an untrusted network!▐\n")
+	}
+	log.Print(readyMsg)
+	if tls {
+		err = http.ServeTLS(listener, mux, certFile, keyFile)
+	} else {
+		err = http.Serve(listener, mux)
+	}
+	log.Fatal(err)
+}