├── client.js
└── server.js


/client.js:
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 1 | const { Socket } = require("net");
 2 | const readline = require("readline").createInterface({
 3 |   input: process.stdin,
 4 |   output: process.stdout,
 5 | });
 6 | 
 7 | const END = "END";
 8 | 
 9 | const error = (message) => {
10 |   console.error(message);
11 |   process.exit(1);
12 | };
13 | 
14 | const connect = (host, port) => {
15 |   console.log(`Connecting to ${host}:${port}`);
16 | 
17 |   const socket = new Socket();
18 |   socket.connect({ host, port });
19 |   socket.setEncoding("utf-8");
20 | 
21 |   socket.on("connect", () => {
22 |     console.log("Connected");
23 | 
24 |     readline.question("Choose your username: ", (username) => {
25 |       socket.write(username);
26 |       console.log(`Type any message to send it, type ${END} to finish`);
27 |     });
28 | 
29 |     readline.on("line", (message) => {
30 |       socket.write(message);
31 |       if (message === END) {
32 |         socket.end();
33 |       }
34 |     });
35 | 
36 |     socket.on("data", (data) => {
37 |       console.log(data);
38 |     });
39 |   });
40 | 
41 |   socket.on("error", (err) => error(err.message));
42 | 
43 |   socket.on("close", () => {
44 |     console.log("Disconnected");
45 |     process.exit(0);
46 |   });
47 | };
48 | 
49 | const main = () => {
50 |   if (process.argv.length !== 4) {
51 |     error(`Usage: node ${__filename} host port`);
52 |   }
53 | 
54 |   let [, , host, port] = process.argv;
55 |   if (isNaN(port)) {
56 |     error(`Invalid port ${port}`);
57 |   }
58 |   port = Number(port);
59 | 
60 |   connect(host, port);
61 | };
62 | 
63 | if (module === require.main) {
64 |   main();
65 | }
66 | 


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/server.js:
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 1 | const { Server } = require("net");
 2 | 
 3 | const host = "0.0.0.0";
 4 | const END = "END";
 5 | 
 6 | const connections = new Map();
 7 | 
 8 | const error = (message) => {
 9 |   console.error(message);
10 |   process.exit(1);
11 | };
12 | 
13 | const sendMessage = (message, origin) => {
14 |   for (const socket of connections.keys()) {
15 |     if (socket !== origin) {
16 |       socket.write(message);
17 |     }
18 |   }
19 | };
20 | 
21 | const listen = (port) => {
22 |   const server = new Server();
23 | 
24 |   server.on("connection", (socket) => {
25 |     const remoteSocket = `${socket.remoteAddress}:${socket.remotePort}`;
26 |     console.log(`New connection from ${remoteSocket}`);
27 |     socket.setEncoding("utf-8");
28 | 
29 |     socket.on("data", (message) => {
30 |       connections.values();
31 |       if (!connections.has(socket)) {
32 |         console.log(`Username ${message} set for connection ${remoteSocket}`);
33 |         connections.set(socket, message);
34 |       } else if (message === END) {
35 |         connections.delete(socket);
36 |         socket.end();
37 |       } else {
38 |         const fullMessage = `[${connections.get(socket)}]: ${message}`;
39 |         console.log(`${remoteSocket} -> ${fullMessage}`);
40 |         sendMessage(fullMessage, socket);
41 |       }
42 |     });
43 | 
44 |     socket.on("error", (err) => console.error(err));
45 | 
46 |     socket.on("close", () => {
47 |       console.log(`Connection with ${remoteSocket} closed`);
48 |     });
49 |   });
50 | 
51 |   server.listen({ port, host }, () => {
52 |     console.log("Listening on port 8000");
53 |   });
54 | 
55 |   server.on("error", (err) => error(err.message));
56 | };
57 | 
58 | const main = () => {
59 |   if (process.argv.length !== 3) {
60 |     error(`Usage: node ${__filename} port`);
61 |   }
62 | 
63 |   let port = process.argv[2];
64 |   if (isNaN(port)) {
65 |     error(`Invalid port ${port}`);
66 |   }
67 | 
68 |   port = Number(port);
69 | 
70 |   listen(port);
71 | };
72 | 
73 | if (require.main === module) {
74 |   main();
75 | }
76 | 


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