messenger.js/server.js

const config = {port: 9091};
var uidcounter = 0;
Object.freeze(config); // Config should not be modified after initialization!

const ChannelStorage = new Map();
const UserAttachedChannelStorage = new Map();
const UserAttachedNameStorage = new Map(); // uid=>username resolve
const ReverseNameToUidStorage = new Map();

/** @section guacamole **/
const ParseCommandString = function(instruction) {
	if(typeof instruction !== "string") {
		return;
	}
	let position = -1;
	let sections = new Array();

	for(;;) {
		let length = instruction.indexOf('.', position + 1);

		if(length === -1) {
			break;
		}

		position = (parseInt(instruction.slice(position + 1, length)) + length) + 1; // todo: not overflow
		sections.push(instruction.slice(length + 1, position)
			.replace(/'/g,	"'")
			.replace(/"/g,	'"')
			.replace(///g,	'/')
			.replace(/&lt;/g,	'<')
			.replace(/&gt;/g,	'>')
			.replace(/&amp;/g,	'&')
		);

		if(instruction.slice(position, position + 1) === ';') {
			break;
		}
	}
	return sections;
}
const EncodeCommandString = function(sections) {
	if(Array.isArray(sections) === false) {
		return;
	}
	let instruction = new String();
	const argv = sections;
	for (let argc = 0; argc < sections.length ; argc++) {
		if(typeof sections[argc] !== "string") {
			argv[argc] = sections[argc].toString();
		}
		argv[argc] = argv[argc]
			.replace(/'/g,	"&#x27;")
			.replace(/"/g,	'&quot;')
			.replace(/\//g,	'&#x2F'	)
			.replace(/</g,	'&lt;'	)
			.replace(/>/g,	'&gt;'	)
			.replace(/&/g,	'&amp;'	)
		;
		instruction = instruction.concat(argv[argc].length.toString(), ".", argv[argc])
		instruction += (argc === sections.length - 1) ? ';' : ',';
	}
	return instruction;
}
/** @section sv_functions **/
const MessageParser = function(webSocket, message, isBinary) {
	const msg = new TextDecoder("utf-8").decode(message);
	if(isBinary) {
		// TODO: command functions
		try {
			const args = ParseCommandString(msg);
			switch(args[0]) {
				case "rename": {
					// todo: make users be able to rename based on parameters given to rename
					var nickname = `guest${Math.floor(Math.random() * 99999)}`;
					// this should probably be a while or something
					if(ReverseNameToUidStorage.get(nickname) !== webSocket.getUserData().uid) {
						nickname = `guest${Math.floor(Math.random() * 99999)}`;
					}
					UserAttachedNameStorage.set(webSocket.getUserData().uid, nickname);
					ReverseNameToUidStorage.set(nickname, webSocket.getUserData().uid);
					webSocket.send(EncodeCommandString(["rename", 0, "", nickname]), true);
					break;
				}
				case "connect": {
					if(args.length <= 1) {
						webSocket.send(EncodeCommandString(["connect", 0]), true);
						break;
					}
					let getChannelId = args[1];
					if(server.numSubscribers(`channels/${getChannelId}`) >= 2) {
						// this room is full
						webSocket.send(EncodeCommandString(["connect", 0]), true);
						break;
					}
					if(typeof UserAttachedNameStorage.get(webSocket.getUserData().uid) === "undefined") {
						// user doesn't have a username
						webSocket.send(EncodeCommandString(["connect", 0]), true);
						break;
					}
					if(typeof ChannelStorage.get(getChannelId) === "undefined") {
						// make the channel right then and there
						ChannelStorage.set(getChannelId, {"owner": webSocket.getUserData().uid});
					};
					if(webSocket.isSubscribed(`channels/${getChannelId}`) === true) {
						// already in this channel
						webSocket.send(EncodeCommandString(["connect", 0]), true);
						break;
					};
					if(typeof UserAttachedChannelStorage.get(webSocket.getUserData().uid) !== "undefined") {
						// already in a channel that isn't the one we're trying to join
						webSocket.send(EncodeCommandString(["connect", 0]), true);
						break;
					}
					webSocket.send(EncodeCommandString(["connect", 1, server.numSubscribers(`channels/${getChannelId}`)]), true);
					webSocket.subscribe(`channels/${getChannelId}`);
					UserAttachedChannelStorage.set(webSocket.getUserData().uid, getChannelId);
					// do we keep adduser?
					if(ChannelStorage.get(getChannelId).owner !== webSocket.getUserData().uid) {
						// send other user's presence if we don't own the channel (if we're not owner)
						webSocket.send(EncodeCommandString(["adduser", 1, UserAttachedNameStorage.get(ChannelStorage.get(getChannelId).owner)]), true);
					}
					// send to other user (or nobody) that we joined this channel
					webSocket.publish(`channels/${getChannelId}`, EncodeCommandString(["adduser", 1, UserAttachedNameStorage.get(webSocket.getUserData().uid)]), true);
					break;
				}
				case "sync": {
					// client is alive...
					break;
				}
				default: {
					console.warn("unknown command", args);
				}
			}
		} catch(e) {
			console.log(e);
			webSocket.end(1003, new TextEncoder("utf-8").encode("Unknown format."));
			return;
		}
		return;
	} else {
		// send data to channel
		webSocket.publish(`channels/${UserAttachedChannelStorage.get(webSocket.getUserData().uid)}`, message, false);
		// ask other user if alive still
		webSocket.publish(`channels/${UserAttachedChannelStorage.get(webSocket.getUserData().uid)}`, EncodeCommandString(["sync", (new Date).getTime()]), true);
	}
	//console.log(`${new TextDecoder("utf-8").decode(webSocket.getRemoteAddressAsText())} message: ${msg}`);
}
const UserStateRequest = function(webSocket, state, data = null) {
	switch(state) {
		case "open": {
			//console.log("%s client hello", new TextDecoder("utf-8").decode(webSocket.getRemoteAddressAsText()));
			break;
		}
		case "close": {
			// close event gets WS disconnect code and the client's termination message (avaliable if data.code is 1000, 3xxx, or 4xxx, but only 1000 is standard)
			// but we DO NOT get to access any WS methods, since they've been closed, so we don't actually know who left.
			if(data.code === 1000) {
				console.log(`client exiting, reason: ${new TextDecoder("utf-8").decode(data.message)}`);
			}
			break;
		}
	}
}
/** @section creation **/
const server = require("uWebSockets.js").App({});
/** @section config **/
server.ws("/connect", {
	// options
	"compression": require("uWebSockets.js").DEDICATED_COMPRESSOR_3KB, // do we need a compressor for this kind of protocol, uWS actively despises compression, so it's worth considering.
	// here be events
	"upgrade": function(rs, rq, cx) {
		rs.upgrade({"uid": (uidcounter++)}, /* very important, this sets a UserData object (which can contain anything we like) to the WSConnection instance. This can only be done here. */
		rq.getHeader("sec-websocket-key"),
		rq.getHeader("sec-websocket-protocol"),
		rq.getHeader("sec-websocket-extensions"),
		cx);
	},
	"message": MessageParser,
	"open": function(ws) {UserStateRequest(ws, "open")},
	"close": function(ws, code, message) {UserStateRequest(ws, "close", {code, message})},
	"drain": function(ws) {console.log(`WS going through back-pressure!: ${ws.getBufferedAmount()}`)}
});
server.listen(config.port, function(token) {console.log(token ? `open on ${config.port}` : `failed to listen to ${config.port}`)});