brainlet/api/v2/gateway/index.js

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const websockets = require("ws");
const { v4 } = require("uuid");
const mongoose = require("mongoose");
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const { policies, gatewayPingInterval, gatewayPingCheckInterval, clientFacingPingInterval } = require("../../../config");
const { experiments } = require("../../../config");
const User = require("../../../models/User");
const Channel = require("../../../models/Channel");
const Message = require("../../../models/Message");
const { parseMessage, packet } = require("./messageparser");
const { checkToken } = require("../../../common/auth/authfunctions");
const wsCloseCodes = {
PAYLOAD_ERROR: [4001, "Error while handling payload"],
NOT_AUTHENTICATED: [4002, "Not authenticated"],
SERVER_DENIED_CONNECTION: [4003, "Server denied connection"],
AUTHENTICATION_ERROR: [4004, "Authentication error"],
TOO_MANY_SESSIONS: [4005, "Too many sessions"],
NOT_AUTHORIZED: [4006, "Not authorized"],
FLOODING: [4007, "Flooding"],
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NO_PING: [4008, "No ping"],
UNSUPPORTED_ATTRIBUTE: [4009, "Unsupported attribute."],
};
const attributes = {
PRESENCE_UPDATES: "PRESENCE_UPDATES",
};
const supportedAttributes = [attributes.PRESENCE_UPDATES];
class GatewaySession {
constructor() {
this.authenticated = false;
this.user = null;
this.token = null;
this.sessionId = v4();
this.attributes = [];
// Specific to websocket sessions
this.isWebsocketConnection = false;
this.ws = null;
this.lastPing = new Date();
this.channels = [];
}
hasAttribute(roleName) {
if (roleName.length < 1) return true; // TODO: HACK
return this.attributes.includes(roleName);
}
setWebsocketClient(ws) {
this.ws = ws;
this.isWebsocketConnection = true;
}
async authenticateWithToken(token) {
let user = null;
try {
user = await checkToken(token);
if (!user) return false;
this.token = token;
this.user = user;
this.authenticated = true;
return true;
} catch(e) {
return false;
}
}
send(name, data) {
this.ws.send(packet(name, data));
}
isReady() {
return this.authenticated && this.ws;
}
}
class GatewayHandler {
constructor() {
this.sessionCounters = {};
}
// server event handlers
handleServerConfigRequest() {
return {
path: "/gateway"
};
}
handleServerReady(wss) {
this.wss = wss;
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this.pingCheckIntervalFunction = setInterval(() => {
this.wss.clients.forEach((client) => {
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if ((new Date() - client.session.lastPing) >= gatewayPingInterval) {
client.close(wsCloseCodes.NO_PING[0], wsCloseCodes.NO_PING[1]);
}
});
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}, gatewayPingCheckInterval);
}
handleServerClose() {
clearInterval(this.pingCheckIntervalFunction);
}
handleConnection(ws) {
if (!policies.allowGatewayConnection) {
return ws.close(wsCloseCodes.SERVER_DENIED_CONNECTION[0], wsCloseCodes.SERVER_DENIED_CONNECTION[1]);
}
const session = new GatewaySession();
session.setWebsocketClient(ws);
session.send("HELLO", { pingInterval: clientFacingPingInterval, supportedAttributes });
return session;
}
handleConnectionClose(ws) {
if (ws.session && ws.session.user && ws.session.channels) {
if (this.sessionCounters[ws.session.user._id] <= 1) {
this.eachInChannel({channelId: ws.session.channels[0], role: attributes.PRESENCE_UPDATES}, (client) => {
if (client.session && client.session.isReady()) {
client.session.send("EVENT_CHANNEL_MEMBERS", {
[ws.session.user._id]: {
_id: ws.session.user._id,
username: ws.session.user.username,
status: 0,
status_text: ""
}
});
}
});
}
this.sessionCounters[ws.session.user._id]--;
if (this.sessionCounters[ws.session.user._id] <= 0) {
this.sessionCounters[ws.session.user._id] = null;
delete this.sessionCounters[ws.session.user._id];
}
}
}
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handleMessage(senderSession, packet) {
return this[`handle_${packet.opcodeType}`](packet, senderSession);
}
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// utility functions
addSessionCounter(id) {
if (!this.sessionCounters[id]) this.sessionCounters[id] = 0;
this.sessionCounters[id]++;
if (this.sessionCounters[id] > policies.perUserMaxGatewayConnections) return false;
return true;
}
getClients() {
return this.wss.clients;
}
eachInChannel({channelId, role=""}, callback) {
const clients = this.getClients();
clients.forEach((client) => {
if (client.session && client.session.isReady() && client.session.hasAttribute(role) && client.session.channels.includes(channelId))
callback(client);
});
}
// Gateway message handlers
async handle_YOO({ data }, session) {
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if (session.authenticated) return {error: wsCloseCodes.PAYLOAD_ERROR};
try {
if (!(await session.authenticateWithToken(data.token))) return {error: wsCloseCodes.AUTHENTICATION_ERROR};
} catch(e) {
return {error: wsCloseCodes.AUTHENTICATION_ERROR};
}
if (!this.addSessionCounter(session.user._id)) return {error: wsCloseCodes.TOO_MANY_SESSIONS};
const channels = (await Channel.find().lean().sort({ _id: -1 }).limit(50).select("-posts -__v").populate("creator", User.getPulicFields(true))) || [];
session.channels = channels.map(x => x._id.toString());
if (data.attributes) {
if (!Array.isArray(data.attributes) || data.attributes.length > 8) return {error: wsCloseCodes.PAYLOAD_ERROR};
for (let i = 0; i < data.attributes.length; i++) {
if (!supportedAttributes.includes(data.attributes[i]))
return {error: wsCloseCodes.UNSUPPORTED_ATTRIBUTE};
}
session.attributes = data.attributes;
}
session.send("YOO_ACK", { session_id: session.sessionId, channels, user: { username: session.user.username, _id: session.user._id }, __global_experiments: experiments });
const channel = session.channels[0];
if (channel) {
const presence = {};
this.eachInChannel({channelId: channel}, ({ session: remoteSession }) => {
presence[remoteSession.user._id] = {
_id: remoteSession.user._id,
username: remoteSession.user.username,
status: 1,
status_text: "Online"
};
if (remoteSession.sessionId !== session.sessionId && remoteSession.hasAttribute(attributes.PRESENCE_UPDATES)) {
remoteSession.send("EVENT_CHANNEL_MEMBERS", {
[session.user._id]: {
_id: session.user._id,
username: session.user.username,
status: 1,
status_text: "Online"
}
});
}
});
(session.hasAttribute(attributes.PRESENCE_UPDATES)) && session.send("EVENT_CHANNEL_MEMBERS", presence);
}
}
async handle_ACTION_PING({ data }, session) {
if (!session.isReady()) return {error: wsCloseCodes.NOT_AUTHENTICATED};
if (data !== "1") throw new Error("msg: ACTION_PING payload data should be a `1`");
const user = await checkToken(session.token);
if (!user) return {error: wsCloseCodes.AUTHENTICATION_ERROR};
session.lastPing = new Date();
}
async handle_ACTION_CREATE_MESSAGE({ data }, session) {
if (!session.isReady()) return {error: wsCloseCodes.NOT_AUTHENTICATED};
if (typeof data.content !== "string" || typeof data.channel !== "object" || typeof data.channel._id !== "string") throw new Error("msg: invalid fields in json payload");
const messageContent = data.content.trim();
if (messageContent.length > 2000 || messageContent.length < 1) return;
if (data.channel._id.length !== 24) throw new Error("msg: payload has invalid id"); // MONGODB ONLY!!
// Check if the user is in that channel before broadcasting the message
if (!session.channels.includes(data.channel._id)) return {error: wsCloseCodes.NOT_AUTHORIZED};
this.eachInChannel({channelId: data.channel._id}, async ({ session: remoteSession }) => {
let id;
if (policies.allowSavingMessages) {
const message = await Message.create({
author: session.user._id,
channel: data.channel._id,
content: messageContent,
createdAt: new Date().getTime()
});
id = message._id;
} else {
id = new mongoose.Types.ObjectId();
}
remoteSession.send("EVENT_CREATE_MESSAGE", {
content: messageContent,
channel: {
_id: data.channel._id
},
author: {
_id: session.user._id,
username: session.user.username
},
_id: id
});
});
}
}
class GatewayServer {
constructor(httpServer) {
this.httpServer = httpServer;
this.wss = null;
this.handler = null;
}
bindHandler(handler) {
if (this.wss) throw new Error("GatewayServer: cannot bindHandler() to a server which already has a bound handler.");
const newHandler = new handler();
this.handler = newHandler;
this.wss = new websockets.Server({ server: this.httpServer, ...(this.handler.handleServerConfigRequest()) });
this.handler.handleServerReady(this.wss);
this.wss.on("close", () => this.handler.handleServerClose());
this.wss.on("connection", (ws) => {
const session = this.handler.handleConnection(ws);
if (!session)
return ws.close();
if (session.__error)
return ws.close(session.__error[0], session.__error[1]);
ws.session = session;
ws.on("message", async (data, isBinary) => {
try {
if (isBinary || !ws.session) return ws.close(wsCloseCodes.PAYLOAD_ERROR[0], wsCloseCodes.PAYLOAD_ERROR[1]);
const status = await this.handler.handleMessage(ws.session, parseMessage(data.toString()));
if (status && status.error) {
return ws.close(status.error[0], status.error[1]);
}
} catch(e) {
console.error("GatewayServer: unexpected error while attempting to handle payload", e);
ws.close(wsCloseCodes.PAYLOAD_ERROR[0], wsCloseCodes.PAYLOAD_ERROR[1]);
}
});
ws.on("close", (code, reason) => {
this.handler.handleConnectionClose(ws, code, reason);
});
});
}
}
module.exports = { GatewayServer, GatewayHandler };