chat-server/main.js

#!/usr/bin/node

// Get some libraries
const random_bytes = require("random-bytes");
const bsplit = require("buffer-split");
const node_rsa = require("node-rsa");
const net = require("net");
const fs = require("fs");

// Load the settings
var settings = require("./settings.json");

console.log("Ready.");

function string_decrypt(key, string)
{
  // Convert the string to a buffer
  var buff = new Buffer.from(string);

  // Create some new data
  var decrypted = new Buffer.alloc(buff.length);

  // Iterate over the string
  for(var i=0;i<string.length;i++)
  {
    // Convert the string item to a number
    var d = buff[i]-key.str[key.at.rx];
    while(d < 0) d += 256;
    decrypted[i] = d;

    // Add 1 to the key counter
    key.at.rx += 1;

    // Is the key counter out of range
    if(key.at.rx >= key.str.length)
    {
      // Set to zero
      key.at.rx = 0;
    }
  }

  // Return the encrypted data
  return decrypted;
}

function string_encrypt(key, string)
{
  // Convert the string to a buffer
  var buff = new Buffer.from(string);

  // Create some new data
  var encrypted = new Buffer.alloc(buff.length);

  // Iterate over the string
  for(var i=0;i<string.length;i++)
  {
    // Convert the string item to a number
    var e = buff[i]+key.str[key.at.tx];
    while(e > 255) e -= 256;
    encrypted[i] = e;

    // Add 1 to the key counter
    key.at.tx += 1;

    // Is the key counter out of range
    if(key.at.tx >= key.str.length)
    {
      // Set to zero
      key.at.tx = 0;
    }
  }

  // Return the encrypted data
  return encrypted;
}

function make_encryption_key(string)
{
  // Make a new key
  var key = new Object();

  // Set the varibles
  key.str = string;
  key.at = new Object();
  key.at.rx = 0;
  key.at.tx = 0;

  // Return the key
  return key;
}

function socket_write(socket, data)
{
  // Send the data encrypted with JSON
  socket.sock.write(string_encrypt(socket.key, JSON.stringify(data)+"\n"));
}

function socket_ondata(socket, callback)
{
  // Wait for a response
  socket.on('data', function(data)
  {
    // Decode the data
    data = JSON.parse(data);

    // Call the callback
    callback(data);
  });
}

function socket_init(socket, callback, ondata)
{
  // Set the socket
  var sock = new Object();
  sock.sock = socket;
  sock.new = true;

  console.log("Connection from "+socket.localAdress);

  // Wait for data
  sock.sock.on('data', function(data)
  {
    // Is the socket new
    if(sock.new)
    {
      // Set sock new
      sock.new = false;

      // Load the key
      var key = new node_rsa();
      key.importKey(data.toString(), 'public');
      console.log("Loaded the RSA key");

      // Get some random bytes
      random_bytes(settings.encryption_key_size, function(error,string)
      {
        // Throw an error if there is one
        if(error) throw error;

        // Make the key
        sock.key = make_encryption_key(string);
        console.log("Created an encryption key")

        // Encrypt the key with RSA
        var key_encrypted = key.encrypt(sock.key.str, 'base64');
        console.log("Encrypted the key");

        // Send the size of the key to the client
        sock.sock.write(key_encrypted.length.toString()+"\n");
        console.log("Sent the size of the key:", key_encrypted.length)

        // Send the key to the client
        sock.sock.write(key_encrypted.toString()+"\n");
        console.log("Sent the key to the client");

        // Send the done signal
        //sock.sock.write("done"+"\n");

        // Call the callback
        setTimeout(callback, 1000, sock);
      });
    }

    else
    {
      // Decrypt the data
      data = string_decrypt(sock.key, data);

      // Split the data by newlines
      data = bsplit(data, Buffer("\n"));

      // Iterate over them
      for(var i=0;i<data.length-1;i++)
      {
        // Send the parsed data to the callback
        console.log(data[i]);
        ondata(JSON.parse(data[i]));
      }
    }
  });

  // Return the socket
  return sock;
}

// Create a server
var server = net.createServer(function(socket)
{
  var sock;

  // Initialise the socket and wait for data
  socket_init(socket, function(socket)
  {
    socket_write(socket, {message: "From the server! :D", array: [1,2,3,4,6,5,"xD",12]});
    sock = socket;
  },
  function(data)
  {
    console.log(data);
    socket_write(sock, {echo: data});
  });
});

// Listen for data
server.listen(22068, '');