VersaWhiteboard/scripts/server-backend.js

const { getArgs } = require("./utils");
const path = require("path");

function startBackendServer(port) {
    var accessToken = ""; //Can be set here or as start parameter (node server.js --accesstoken=MYTOKEN)
    var disableSmallestScreen = false; //Can be set to true if you dont want to show (node server.js --disablesmallestscreen=true)
    var webdav = false; //Can be set to true if you want to allow webdav save (node server.js --webdav=true)
    
    var fs = require("fs-extra");
    var express = require('express');
    var formidable = require('formidable'); //form upload processing
    
    const createDOMPurify = require('dompurify'); //Prevent xss
    const { JSDOM } = require('jsdom');
    const window = (new JSDOM('')).window;
    const DOMPurify = createDOMPurify(window);
    
    const { createClient } = require("webdav");
    
    var s_whiteboard = require("./s_whiteboard.js");
    
    var app = express();
    app.use(express.static(path.join(__dirname, '..', 'dist')));
    app.use("/uploads", express.static(path.join(__dirname, '..', 'public', 'uploads')));
    var server = require('http').Server(app);
    server.listen(port);
    var io = require('socket.io')(server, {path: "/ws-api", });
    console.log("Webserver & socketserver running on port:" + port);
    if (process.env.accesstoken) {
        accessToken = process.env.accesstoken;
    }
    if (process.env.disablesmallestscreen) {
        disablesmallestscreen = true;
    }
    if (process.env.webdav) {
        webdav = true;
    }
    
    var startArgs = getArgs();
    if (startArgs["accesstoken"]) {
        accessToken = startArgs["accesstoken"];
    }
    if (startArgs["disablesmallestscreen"]) {
        disableSmallestScreen = true;
    }
    if (startArgs["webdav"]) {
        webdav = true;
    }
    
    if (accessToken !== "") {
        console.log("AccessToken set to: " + accessToken);
    }
    if (disableSmallestScreen) {
        console.log("Disabled showing smallest screen resolution!");
    }
    if (webdav) {
        console.log("Webdav save is enabled!");
    }
    
    app.get('/api/loadwhiteboard', function (req, res) {
        var wid = req["query"]["wid"];
        var at = req["query"]["at"]; //accesstoken
        if (accessToken === "" || accessToken == at) {
            var ret = s_whiteboard.loadStoredData(wid);
            res.send(ret);
            res.end();
        } else {
            res.status(401);  //Unauthorized
            res.end();
        }
    });
    
    app.post('/api/upload', function (req, res) { //File upload
        var form = new formidable.IncomingForm(); //Receive form
        var formData = {
            files: {},
            fields: {}
        }
    
        form.on('file', function (name, file) {
            formData["files"][file.name] = file;
        });
    
        form.on('field', function (name, value) {
            formData["fields"][name] = value;
        });
    
        form.on('error', function (err) {
            console.log('File uplaod Error!');
        });
    
        form.on('end', function () {
            if (accessToken === "" || accessToken == formData["fields"]["at"]) {
                progressUploadFormData(formData, function (err) {
                    if (err) {
                        if (err == "403") {
                            res.status(403);
                        } else {
                            res.status(500);
                        }
                        res.end();
                    } else {
                        res.send("done");
                    }
                });
            } else {
                res.status(401);  //Unauthorized
                res.end();
            }
            //End file upload
        });
        form.parse(req);
    });
    
    function progressUploadFormData(formData, callback) {
        console.log("Progress new Form Data");
        var fields = escapeAllContentStrings(formData.fields);
        var files = formData.files;
        var whiteboardId = fields["whiteboardId"];
    
        var name = fields["name"] || "";
        var date = fields["date"] || (+new Date());
        var filename = whiteboardId + "_" + date + ".png";
        var webdavaccess = fields["webdavaccess"] || false;
        try {
            webdavaccess = JSON.parse(webdavaccess);
        } catch (e) {
            webdavaccess = false;
        }
        fs.ensureDir("./public/uploads", function (err) {
            if (err) {
                console.log("Could not create upload folder!", err);
                return;
            }
            var imagedata = fields["imagedata"];
            if (imagedata && imagedata != "") { //Save from base64 data
                imagedata = imagedata.replace(/^data:image\/png;base64,/, "").replace(/^data:image\/jpeg;base64,/, "");
                console.log(filename, "uploaded");
                fs.writeFile('./public/uploads/' + filename, imagedata, 'base64', function (err) {
                    if (err) {
                        console.log("error", err);
                        callback(err);
                    } else {
                        if (webdavaccess) { //Save image to webdav
                            if (webdav) {
                                saveImageToWebdav('./public/uploads/' + filename, filename, webdavaccess, function (err) {
                                    if (err) {
                                        console.log("error", err);
                                        callback(err);
                                    } else {
                                        callback();
                                    }
                                })
                            } else {
                                callback("Webdav is not enabled on the server!");
                            }
                        } else {
                            callback();
                        }
                    }
                });
            } else {
                callback("no imagedata!");
                console.log("No image Data found for this upload!", name);
            }
        });
    }
    
    function saveImageToWebdav(imagepath, filename, webdavaccess, callback) {
        if (webdavaccess) {
            var webdavserver = webdavaccess["webdavserver"] || "";
            var webdavpath = webdavaccess["webdavpath"] || "/";
            var webdavusername = webdavaccess["webdavusername"] || "";
            var webdavpassword = webdavaccess["webdavpassword"] || "";
    
            const client = createClient(
                webdavserver,
                {
                    username: webdavusername,
                    password: webdavpassword
                }
            )
            client.getDirectoryContents(webdavpath).then((items) => {
                var cloudpath = webdavpath+ '' + filename;
                console.log("webdav saving to:", cloudpath);
                fs.createReadStream(imagepath).pipe(client.createWriteStream(cloudpath));
                callback();
            }).catch((error) => {
                callback("403");
                console.log("Could not connect to webdav!")
            });
        } else {
            callback("Error: no access data!")
        }
    }
    
    var smallestScreenResolutions = {};
    io.on('connection', function (socket) {
        var whiteboardId = null;
    
        socket.on('disconnect', function () {
            if (smallestScreenResolutions && smallestScreenResolutions[whiteboardId] && socket && socket.id) {
                delete smallestScreenResolutions[whiteboardId][socket.id];
            }
            socket.broadcast.emit('refreshUserBadges', null); //Removes old user Badges
            sendSmallestScreenResolution();
        });
    
        socket.on('drawToWhiteboard', function (content) {
            content = escapeAllContentStrings(content);
            if (accessToken === "" || accessToken == content["at"]) {
                socket.broadcast.to(whiteboardId).emit('drawToWhiteboard', content); //Send to all users in the room (not own socket)
                s_whiteboard.handleEventsAndData(content); //save whiteboardchanges on the server
            } else {
                socket.emit('wrongAccessToken', true);
            }
        });
    
        socket.on('joinWhiteboard', function (content) {
            content = escapeAllContentStrings(content);
            if (accessToken === "" || accessToken == content["at"]) {
                whiteboardId = content["wid"];
                socket.join(whiteboardId); //Joins room name=wid
                smallestScreenResolutions[whiteboardId] = smallestScreenResolutions[whiteboardId] ? smallestScreenResolutions[whiteboardId] : {};
                smallestScreenResolutions[whiteboardId][socket.id] = content["windowWidthHeight"] || { w: 10000, h: 10000 };
                sendSmallestScreenResolution();
            } else {
                socket.emit('wrongAccessToken', true);
            }
        });
    
        socket.on('updateScreenResolution', function (content) {
            content = escapeAllContentStrings(content);
            if (accessToken === "" || accessToken == content["at"]) {
                smallestScreenResolutions[whiteboardId][socket.id] = content["windowWidthHeight"] || { w: 10000, h: 10000 };
                sendSmallestScreenResolution();
            }
        });
    
        function sendSmallestScreenResolution() {
            if (disableSmallestScreen) {
                return;
            }
            var smallestWidth = 10000;
            var smallestHeight = 10000;
            for (var i in smallestScreenResolutions[whiteboardId]) {
                smallestWidth = smallestWidth > smallestScreenResolutions[whiteboardId][i]["w"] ? smallestScreenResolutions[whiteboardId][i]["w"] : smallestWidth;
                smallestHeight = smallestHeight > smallestScreenResolutions[whiteboardId][i]["h"] ? smallestScreenResolutions[whiteboardId][i]["h"] : smallestHeight;
            }
            io.to(whiteboardId).emit('updateSmallestScreenResolution', { w: smallestWidth, h: smallestHeight });
        }
    });
    
    //Prevent cross site scripting (xss)
    function escapeAllContentStrings(content, cnt) {
        if (!cnt)
            cnt = 0;
    
        if (typeof (content) === "string") {
            return DOMPurify.sanitize(content);
        }
        for (var i in content) {
            if (typeof (content[i]) === "string") {
                content[i] = DOMPurify.sanitize(content[i]);
            } if (typeof (content[i]) === "object" && cnt < 10) {
                content[i] = escapeAllContentStrings(content[i], ++cnt);
            }
        }
        return content;
    }
    
    process.on('unhandledRejection', error => {
        // Will print "unhandledRejection err is not defined"
        console.log('unhandledRejection', error.message);
    })
}

module.exports = startBackendServer;