townsquare/server/index.js

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const fs = require("fs");
const https = require("https");
const WebSocket = require("ws");
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const PING_INTERVAL = 30000; // 30 seconds
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const server = https.createServer({
cert: fs.readFileSync("cert.pem"),
key: fs.readFileSync("key.pem")
});
const wss = new WebSocket.Server({
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...(process.env.NODE_ENV === "development" ? { port: 8081 } : { server }),
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verifyClient: info =>
!!info.origin.match(
/^https?:\/\/([^.]+\.github\.io|localhost|live\.clocktower\.online|eddbra1nprivatetownsquare\.xyz)/i
)
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});
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function noop() {}
// calculate latency on heartbeat
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function heartbeat() {
this.latency = Math.round((new Date().getTime() - this.pingStart) / 2);
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this.counter = 0;
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this.isAlive = true;
}
// map of channels currently in use
const channels = {};
// a new client connects
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wss.on("connection", function connection(ws, req) {
ws.channel = req.url
.split("/")
.pop()
.toLocaleLowerCase();
if (ws.channel.match(/-host$/i)) {
ws.isHost = true;
ws.channel = ws.channel.substr(0, ws.channel.length - 5);
// check for another host on this channel
if (
channels[ws.channel] &&
channels[ws.channel].some(
client =>
client !== ws && client.readyState === WebSocket.OPEN && client.isHost
)
) {
console.log(ws.channel, "duplicate host");
ws.close(1000, `The channel "${ws.channel}" already has a host`);
return;
}
}
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ws.isAlive = true;
ws.pingStart = new Date().getTime();
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ws.counter = 0;
// add channel to list
if (!channels[ws.channel]) {
channels[ws.channel] = [];
}
channels[ws.channel].push(ws);
// start ping pong
ws.ping(noop);
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ws.on("pong", heartbeat);
// remove client from channels on close
ws.on("close", () => {
const index = channels[ws.channel].indexOf(ws);
if (index >= 0) {
channels[ws.channel].splice(index, 1);
}
if (!channels[ws.channel].length) delete channels[ws.channel];
});
// handle message
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ws.on("message", function incoming(data) {
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// check rate limit (max 5msg/second)
ws.counter++;
if (ws.counter > (5 * PING_INTERVAL) / 1000) {
console.log(ws.channel, "disconnecting user due to spam");
ws.close(
1000,
"Your app seems to be malfunctioning, please clear your browser cache."
);
return;
}
const isPing = data.match(/^\["ping/i);
if (!isPing) {
console.log(new Date(), wss.clients.size, ws.channel, data);
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}
channels[ws.channel].forEach(function each(client) {
if (client !== ws && client.readyState === WebSocket.OPEN) {
// inject latency between both clients if ping message
if (isPing && client.latency && ws.latency) {
client.send(data.replace(/latency/, client.latency + ws.latency));
} else {
client.send(data);
}
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}
});
});
});
// start ping interval timer
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const interval = setInterval(function ping() {
wss.clients.forEach(function each(ws) {
if (ws.isAlive === false) return ws.terminate();
ws.isAlive = false;
ws.pingStart = new Date().getTime();
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ws.ping(noop);
});
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}, PING_INTERVAL);
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// handle server shutdown
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wss.on("close", function close() {
clearInterval(interval);
});
// prod mode with stats API
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if (process.env.NODE_ENV !== "development") {
console.log("server starting");
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server.listen(8080);
server.on("request", (req, res) => {
res.writeHead(200);
res.end(
JSON.stringify({
players: wss.clients.size,
channels: Object.keys(channels).length
})
);
});
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}